JP2007243076A - Light emitting device and manufacturing method of light emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that reliability declines due to expansion and contraction behaviors by thermal shock. <P>SOLUTION: The light emitting device is provided with a resin coating layer 40 for coating the periphery of a light emitting element 10 in the state of mounting the light emitting element 10 on a sub mount substrate 20, a buffer layer 32 composed of an air layer is formed in a space between the light emitting element 10 and the sub mount substrate 20, a resin forming the coating layer 40 forms a spacer layer 42 at the end part of the space formed between the light emitting element 10 and the sub mount substrate 20 from the periphery of the light emitting element 10, and the coating layer 40 and the spacer layer 42 are integrally formed by the same member. By intentionally forming the buffer layer 32 of the air layer between the light emitting element 10 and the sub mount substrate 20 in such a manner, the thermal shock resistance of the light emitting device is improved and reliability when mounting the sub mount substrate 20 on a support body 50 or the like eutectically or the like is improved. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a light emitting device in which a light emitting element is mounted on a submount substrate, and a method for manufacturing the light emitting device.

  A light-emitting device using a semiconductor element as a light-emitting element emits light with a small color, high power efficiency, and vivid colors. In addition, a light emitting element which is a semiconductor element does not have a concern about a broken ball. Further, it has excellent initial driving characteristics and is strong against vibration and repeated on / off lighting. Because of such excellent characteristics, light-emitting devices using semiconductor light-emitting elements such as light-emitting diodes (LEDs) and laser diodes (LDs) are used as various light sources. In particular, a high-luminance blue light-emitting LED using a GaN-based compound semiconductor has been developed, and a white light-emitting device has been realized by utilizing the luminance. In this white light emitting device, a light emitting element emitting blue light is covered with a resin containing a fluorescent material emitting yellow light to obtain white light.

  In addition to such a light emitting element, a transistor, a thyristor, or the like is used as a semiconductor element for switching applications, power control, and the like. In mounting such a semiconductor element, in order to improve workability, a configuration in which the semiconductor device is once mounted on a submount substrate which is a small substrate and then mounted on a larger support by die bonding or the like is employed.

  In order to increase the output of the semiconductor element, it is necessary to increase the input current. In particular, in response to the demand for higher output in recent years, high-power LEDs have been developed, and on the other hand, a plurality of such semiconductor elements are used in combination. For example, RGB LED chips are arranged in one package. Thus, light emitting elements capable of emitting full color have been developed. As the output of such semiconductor elements is increased or the number of used semiconductor devices is increased, the amount of heat generation is also increasing. In order to prevent the semiconductor element function from deteriorating due to heat generation of the semiconductor element, it is necessary to take some heat dissipation measures.

For example, consider a case where a semiconductor light emitting element such as an LED or LD is flip-chip mounted on a submount substrate via bumps or the like so that the light emitting surface is on the substrate side. This submount substrate is further mounted on a support by eutectic or the like. In general, when a light emitting element is flip-chip mounted on a submount substrate via a bump, a space is formed between the light emitting element and the submount substrate corresponding to the height of the bump. In the field of light-emitting elements, since light-emitting elements generate heat, it is necessary to mitigate thermal expansion and mechanical stress. For this reason, the space formed between the light emitting element and the submount substrate is filled with an underfill material such as a resin to improve the heat conduction between the light emitting element and the submount substrate via the underfill resin. In order to improve the heat dissipation efficiency and improve the adhesion between the light emitting element and the submount substrate, the reliability is improved. As described above, conventionally, it is preferable that no gap is generated between the light emitting element and the submount substrate, and processing such as coating of the resin layer by printing under vacuum has been performed.
JP 2001-284400 A

  However, as a result of detailed investigations on the adhesion between the light emitting element and the submount substrate, the present inventors have found that the adhesion deteriorates rather depending on the linear expansion coefficient of the underfill resin. That is, when an underfill resin having a large linear expansion coefficient is used, the underfill resin 60 expands between the light emitting element 610 and the submount substrate 620 due to heat as shown in FIG. It has been found that a stress is generated that causes the mounting substrate 620 to peel off. This is because when the submount substrate 620 is further mounted on the support by eutectic, the light emitting element 610 is peeled off from the submount substrate 620 by the heat of about 300 ° C. required for the eutectic process, or the adhesive force therebetween. This causes a problem that the reliability deteriorates due to the decrease in the reliability.

  On the other hand, there is also a problem that reliability may be impaired due to deformation of the light emitting element itself. Many light-emitting elements are formed by epitaxially growing a semiconductor layer such as a gallium nitride-based compound semiconductor layer on a sapphire substrate. However, the sapphire substrate is generally considerably thicker than the epitaxially grown layer. As shown in exaggerated manner in FIG. 11, the sapphire substrate 612 and the gallium nitride compound semiconductor layer 614 have different linear expansion coefficients. It will be in a state of warping. When this light-emitting element is flip-chip mounted on a submount substrate 620 such as aluminum nitride via bumps 630 or the like, the light-emitting element 610 is mounted in an upwardly warped state as shown in FIG. On the other hand, when the submount substrate 620 is mounted on the support as a eutectic as described above, a thermal history is generated by heating during the eutectic process, and the warp of the sapphire substrate 612 is restored, that is, from a mountain shape to a valley shape. Stress to warp is generated. As a result, as shown in FIG. 13, a pressing force acts on the bump 630A located in the vicinity of the end of the light emitting element 610 in a direction to crush it, and the bump 630A is peeled relatively upward with respect to the bump 630B near the center. The stress to be worked will work. For this reason, there is also a problem that the adhesiveness between the light emitting element 610 and the submount substrate 620 is lowered even by deformation of the light emitting element itself due to heat.

  The present invention has been made to solve such conventional problems. The main object of the present invention is to solve the problem of lowering reliability due to expansion and contraction behavior due to thermal shock, and further improve the adhesiveness between the submount substrate and the light emitting element to improve the reliability and the light emitting device It is to provide a method for manufacturing an apparatus.

  In order to achieve the above object, a first light emitting device of the present invention includes a light emitting element, a submount substrate on which a light emitting element can be flip-chip mounted via a conductive bonding material, and a light emitting element. A resin coating layer covering the periphery of the light emitting element in a state mounted on the substrate, and a buffer layer made of an air layer is formed in a space between the light emitting element and the submount substrate, and the coating layer Forming a spacer layer from the periphery of the light emitting element to the end of the space formed between the light emitting element and the submount substrate, and the covering layer and the spacer layer are integrally formed by the same member. Further, as a characteristic of the resin, when forming the coating layer, a part of the resin is allowed to enter between the light emitting element and the submount substrate from the side surface of the light emitting element, and the spacer layer is formed at the end. Can form a flow It has been adjusted to the characteristics. In this way, by deliberately forming a buffer layer of the air layer between the light emitting element and the submount substrate, the thermal shock resistance of the light emitting device is improved, and the submount substrate is mounted on a support with eutectic crystal or the like. Reliability can be improved. In addition, when the resin is coated on the light emitting element, the flow characteristics are adjusted so that the resin does not completely enter between the light emitting element and the submount substrate. It can be secured.

  In addition, the second light emitting device includes a light emitting element, a submount substrate on which the light emitting element is flip-chip mountable via a conductive bonding material, and a light emitting element mounted on the submount substrate. A resin coating layer covering the periphery of the light emitting element, a buffer layer made of an air layer is formed in a space between the light emitting element and the submount substrate, and a resin that forms the coating layer A spacer layer is formed from the periphery of the light emitting element to an end portion of a space formed between the light emitting element and the submount substrate, and the covering layer and the spacer layer are integrally formed of the same member. Thus, the area ratio of the buffer layer and the spacer layer provided in the space between the light emitting element and the submount substrate is 9: 1 to 5: 5. In this way, by deliberately forming a buffer layer of the air layer between the light emitting element and the submount substrate, the thermal shock resistance of the light emitting device is improved, and the submount substrate is mounted on a support with eutectic crystal or the like. Reliability can be improved. In particular, by setting the ratio between the buffer layer and the spacer layer within this range, the mechanical strength of the joint portion by the conductive joint material can be maintained.

  Furthermore, the third light emitting device is a semiconductor light emitting element chip formed by epitaxially growing a light emitting element on a sapphire substrate. Thereby, a light-emitting device suitable for mounting a semiconductor light-emitting element chip such as an LED or an LD is realized. In particular, the warp caused by the difference in the coefficient of linear expansion between the sapphire substrate and the epitaxial growth layer can be countered by the spacer layer against the stress that tries to return in the opposite direction due to the thermal history. Etc. can be avoided.

  Furthermore, in the fourth light emitting device, the coating layer is a wavelength conversion layer made of a translucent resin and containing a fluorescent material that receives light emitted from the light emitting element and converts the wavelength of the light. Thereby, mixed color light of the light of the light emitting element and the light wavelength-converted by the fluorescent material of the wavelength conversion layer can be emitted to the outside.

  Furthermore, in the fifth light emitting device, the resin constituting the coating layer is a silicone resin. As a result, even if a silicone resin having a large linear expansion coefficient is used, the light emitting device can be prevented from peeling off from the submount substrate due to thermal shock, and the light emitting device is improved in reliability and excellent in light resistance due to the silicone resin. Can be realized.

  Furthermore, the sixth light emitting device further includes a support for mounting the submount substrate on the upper surface, and the submount substrate is mounted on the support via a eutectic layer. Thereby, a highly reliable light-emitting device that can withstand thermal shock during eutectic is realized.

  Furthermore, in the seventh light emitting device, the conductive bonding material is a bump. As a result, the bonding strength of the light emitting element in which the light emitting element is flip-chip mounted by bump bonding can be improved.

Furthermore, the eighth light emitting device adjusts the viscosity at 23 ° C. to 1 × 10 Pa · s to 1 × 10 ⁵ Pa · s and the thixotropic coefficient to 1.0 to 15.0 as the flow characteristics of the resin. . The buffer layer can be easily formed by adjusting the flow characteristics of the resin within the above range.

Furthermore, in the ninth light emitting device, the resin is (a) the following average composition formula (1):
R ¹ _a (OX) _b SiO _{(4-ab) / 2} (1)
(Wherein R ¹ is independently an alkyl group having 1 to 6 carbon atoms, an alkenyl group, or an aryl group, and X is independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkenyl group. , An alkoxyalkyl group or an acyl group, a is a number from 1.05 to 1.5, b is a number satisfying 0 <b <2, provided that a + b satisfies 1.05 <a + b <2. An organopolysiloxane having a polystyrene equivalent weight average molecular weight of 5 × 10 ³ or more,
(B) a condensation catalyst,
(C) It consists of hardened | cured material of the curable silicone resin composition containing a solvent and (d) fine powder inorganic filler. By using this resin, the flow characteristics can be easily adjusted, and sufficient mechanical strength of the joined portion by the conductive joining material can be obtained.

  Furthermore, a tenth light emitting device manufacturing method is a method for manufacturing a light emitting device in which a light emitting element is flip-chip mounted on a submount substrate, and the light emitting element is mounted on the submount substrate via a conductive bonding material. The flip chip mounting process and the light emitting element mounted on the submount substrate, the upper surface and the side surface of the light emitting element are covered with resin, and an end portion is formed in the space formed between the light emitting element and the submount substrate. A step of applying a resin whose flow characteristics have been adjusted so as to allow a part of the resin to enter from the stencil printing, a coating layer covering the periphery of the light emitting element by curing the resin, and the light emitting element A step of integrally forming a spacer layer positioned at an end of a space between the submount substrate and simultaneously forming a buffer layer made of an air layer between the light emitting element and the submount substrate; Including. Thereby, it becomes easy to form a buffer layer between the light emitting element and the submount substrate without using a special member such as a dam.

  Furthermore, in the eleventh light emitting device manufacturing method, the step of applying the resin is performed by atmospheric printing. As a result, it is possible to avoid a situation where the resin penetrates excessively between the light emitting element and the submount substrate and obstructs the formation of the buffer layer.

  Furthermore, in the twelfth light emitting device manufacturing method, the time between the step of applying the resin by printing and the step of curing the resin is controlled, so that the space formed between the light emitting element and the submount substrate is controlled. The amount of resin entering from the end is adjustable. In this way, the amount of resin penetration can be adjusted by the standing time after printing, whereby a spacer layer having a desired size can be formed.

  According to the light emitting device and the method for manufacturing the light emitting device of the present invention, an air layer is intentionally formed as a buffer layer between the light emitting element and the submount substrate, thereby dispersing or reducing stress due to expansion or deformation due to heat. As a result, the mechanical strength of the bonded portion by the conductive bonding material can be maintained, and the reliability can be improved. In addition, by improving the heat resistance, mounting by eutectic or reflow is possible, and an easy-to-use light emitting device can be realized.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiment described below exemplifies a light emitting device and a method for manufacturing the light emitting device for embodying the technical idea of the present invention, and the present invention describes the method for manufacturing the light emitting device and the light emitting device as follows. Not specific to anything. Further, the present specification by no means specifies the members shown in the claims to the members of the embodiments. In particular, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in the embodiments are not intended to limit the scope of the present invention unless otherwise specified, and are merely explanations. It's just an example. Note that the size, positional relationship, and the like of the members shown in each drawing may be exaggerated for clarity of explanation. Further, in the following description, the same name and reference numeral indicate the same or the same members, and detailed description will be omitted as appropriate. Furthermore, each element constituting the present invention may be configured such that a plurality of elements are constituted by the same member and the plurality of elements are shared by one member, and conversely, the function of one member is constituted by a plurality of members. It can also be realized by sharing.
(Embodiment 1)

  FIG. 1 shows a cross-sectional view of the light-emitting device according to Embodiment 1 of the present invention. The light-emitting device 100 shown in this figure includes a light-emitting element 10, a submount substrate 20 on which the light-emitting element 10 is mounted, a support 50 to which the submount substrate 20 is further fixed, and the light-emitting element 10 and the upper surface of the support 50. And a lens 70 covering the submount substrate 20. The submount substrate 20 and the support body 50 are mechanically fixed via the eutectic layer 80. The support 50 is provided with an electrode 90 penetrating therethrough, and is electrically connected to the submount substrate 20 through a wire 92 wire-bonded to the electrode 90 on the upper surface of the support 50. The lens 70 has an optically curved surface in order to efficiently extract the light from the light emitting element 10 to the outside. In the example of FIG. 1, the inner surface of the lens 70 is hollow. The lens 70 is fixed to the upper surface of the support 50 through an adhesive or the like.

FIG. 2 is a cross-sectional view of the submount substrate 20 and the light emitting element 10 constituting the light emitting device of FIG. Hereinafter, in order to describe in detail the bonding between the submount substrate 20 and the light emitting element 10, a description will be given based on FIG. FIG. 2 shows a submount structure in which the light emitting element 10 is mounted on the submount substrate 20. The light emitting element 10 is flip-chip mounted on the submount substrate 20 via the bumps 30 that are conductive bonding materials so that the light emitting surface faces the submount substrate 20. Flip chip mounting is also called face-down bonding, and has a configuration in which the growth substrate 12 side of the light emitting element 10 is arranged on the viewing side, and the emitted light is reflected by a reflective layer or the like to be taken out from the growth substrate 12 side. Point to. Of course, it is also possible to perform flip chip mounting after finally removing the growth substrate from the light emitting element.
(Light emitting element 10)

  As the light emitting element 10, a semiconductor light emitting element such as an LED or an LD (semiconductor laser) can be used. These semiconductor light emitting devices have the advantage that the linearity of the output with respect to the input is good, the efficiency is excellent, and the long life can be used stably. In particular, LEDs are preferable because they are inexpensive and readily available. In particular, in this embodiment, a surface mount type (SMD) light emitting element chip in which a p-side electrode and an n-side electrode are formed on the same surface side and can be easily mounted on a submount substrate can be suitably used. Further, in this embodiment, since the light emitting element 10 is flip-chip mounted, it is necessary to have a configuration in which light emitted to the substrate surface side is reflected and emitted to the sapphire substrate side. For this reason, a reflective film is formed on the bottom surface.

  As the light emitting element 10, a semiconductor light emitting element in which the semiconductor layer 14 is epitaxially grown on the growth substrate 12 can be suitably used. The growth substrate 12 is not limited to sapphire, and known members such as spinel, SiC, GaN, and GaAs can be used. In addition, by using a conductive substrate such as SiC, GaN, or GaAs instead of an insulating substrate such as sapphire, the p electrode and the n electrode can be arranged to face each other.

Examples of the material of the semiconductor layer 14 include various semiconductors such as BN, SiC, ZnSe, GaN, InGaN, InAlGaN, AlGaN, BAlGaN, and BInAlGaN. Similarly, these elements may contain Si, Zn, or the like as an impurity element to serve as a light emission center. As a material of the light emitting layer, a nitride semiconductor (for example, a nitride semiconductor containing Al or Ga, a nitride semiconductor containing In or Ga, In _X Al _Y Ga _1-XY N (0 <X <1, 0 <Y < 1, X + Y ≦ 1), etc. The semiconductor structure is preferably a homostructure having a MIS junction, PIN junction or pn junction, heterostructure, or double hetero structure. The emission wavelength can be selected in various ways depending on the material and its mixed crystal ratio, and the output can be increased by adopting a single quantum well structure or a multiple quantum well structure in which the semiconductor active layer is formed in a thin film that produces a quantum effect. It can also be improved.

In this specification, the light emitting element is not limited to its name, but is used to include a light receiving element such as a photodiode (PD) or CCD, and an optical element such as an imaging element.
(Submount substrate 20)

  The submount substrate 20 has a light emitting element mounting surface 21 on which the light emitting element 10 is mounted on one main surface (upper surface in FIG. 2). Further, since the submount substrate 20 is further mounted on the support 50 or the like as necessary, the support mounting surface 22 can be formed on the opposite surface side facing the light emitting element mounting surface 21.

  Note that a submount substrate is typically a substrate on which a light emitting element is mounted, and further refers to an intermediate substrate for mounting the submount substrate on another substrate such as a support. The submount substrate means a substrate on which a light emitting element is widely mounted, and does not necessarily require mounting on another substrate thereafter.

  On the upper surface of the submount, a positive electrode and a negative electrode are formed as an electrode 94 by a conductive member, and these are insulated from each other by an insulating film. As the conductive member, it is preferable to use a silver-white metal, particularly aluminum, silver, gold, or an alloy thereof having high reflectivity.

  The material constituting the submount substrate 20 is preferably a material having a thermal expansion coefficient substantially equal to that of the light emitting element 10 to be mounted. For example, when the light emitting element 10 is a nitride compound semiconductor light emitting element, aluminum nitride is preferable. By using such a material, the thermal stress generated between the submount substrate 20 and the light emitting element 10 is relieved, and the electrical connection via the bumps 30 between the submount and the light emitting element 10 is maintained. Therefore, the reliability of the light emitting device can be improved. Alternatively, silicon that can constitute a protective element that prevents the light emitting element 10 from being destroyed by overvoltage can also be used. For example, a protective element such as a Zener diode or a capacitor can be incorporated in the submount substrate 20.

The submount substrate 20 is formed by cutting a wafer into a predetermined size and shape. FIG. 3 shows an example of the wafer 24 before cutting on which the submount substrate is formed. As described above, a region corresponding to the submount substrate is provided on the wafer 24 in a predetermined pattern, each of the light emitting elements 10 is mounted and an electrode pattern is formed, and then the wafer 24 is cut out to form the submount substrate 20. .
(Protective element)

  As the protective element, a zener diode that becomes energized when a voltage higher than a specified voltage is applied, a capacitor that absorbs a pulsed voltage, or the like can be used. The submount functioning as a Zener diode has a p-type semiconductor region having a positive electrode and an n-type semiconductor region having a negative electrode, and is in reverse parallel to the p-side electrode and the n-side electrode of the light emitting element 10. So that they are connected. That is, the n-side pad electrode and the p-side electrode of the light emitting element 10 are electrically and mechanically connected to the positive electrode and the negative electrode provided in the p-type semiconductor region and the n-type semiconductor region of the submount by the bumps 30, respectively. The Furthermore, both the positive and negative electrodes provided on the submount are connected to an external electrode such as a lead electrode by a conductive wire. Note that a back electrode having the same polarity as that of either the p-type semiconductor region or the n-type semiconductor region, for example, the p-type semiconductor region, is provided on the surface facing the main surface of the submount on which the light emitting element 10 is mounted. Further, it is possible to conduct directly with the lead electrode without using a conductive wire.

By giving the submount the function of a Zener diode, when an excessive voltage is applied between the electrodes, if the voltage exceeds the Zener voltage of the Zener diode, the positive and negative electrodes of the light emitting element 10 are held at the Zener voltage. And never exceed this Zener voltage. Therefore, it is possible to prevent an excessive voltage from being applied between the light emitting elements 10, protect the light emitting element 10 from an excessive voltage, and prevent the occurrence of element destruction and performance deterioration. Here, if each of the light emitting element 10 and the protective element is die-bonded to a package or the like and then connected to the external electrode with a conductive wire, the productivity decreases because the number of bonding of the conductive wire increases. In addition, since there is an increased risk of contact between the conductive wires, disconnection, and the like, the reliability of the light emitting device may be reduced. On the other hand, in the light emitting device in this embodiment, the conductive wire only needs to be connected to both the positive and negative electrodes provided on the submount, and there is no need to bond the conductive wire to the light emitting element 10, so the above-described problem Therefore, a highly reliable light-emitting device can be obtained.
(Bump 30)

  The light emitting element 10 and the submount substrate 20 are electrically and mechanically bonded via a conductive bonding material. In the example of FIG. 2, bumps are used, and the p-side electrode and the n-side electrode of the light emitting element 10 are mechanically fixed so as to face both the positive and negative electrodes formed on the same surface side of the submount. First, bumps 30 made of Au are formed on both the positive and negative electrodes of the submount substrate 20. Next, the pad electrode of the light emitting element 10 and the electrode of the submount substrate 20 are opposed to each other through the bump 30, and the bump 30 is welded by applying a load, heat, ultrasonic waves, etc. The electrode with the mount substrate 20 is joined.

  In addition to Au, eutectic solder (Au—Sn), Pb—Sn, lead-free solder or the like can be used as the material of the bump 30. Further, the shape and size of the pad electrode of the light emitting element are appropriately selected depending on the size and number of bumps to be installed.

Further, the submount substrate 20 may be a light emitting device in which Ag paste is fixed as an adhesive on a support 50 such as a package described later or a lead electrode, and the lead electrode and the submount electrode are connected by a conductive wire. Good.
(Buffer layer 32)

  A buffer layer 32 that is an air layer is formed between the light emitting element 10 and the submount substrate 20. Conventionally, when a semiconductor element is mounted on a submount substrate, an underfill material is filled under reduced pressure so that an air layer is not formed in the space formed at the interface between the semiconductor element and the submount substrate. It has been broken. Since the air layer has high heat insulation properties, it is intended to prevent heat generated in the semiconductor element from being efficiently conducted to the submount substrate and to improve the adhesion between the semiconductor element and the submount substrate. As the underfill material, an epoxy resin having a low linear expansion and shrinkage stress due to curing shrinkage is widely used.

  On the other hand, in the field of light-emitting elements, the resin disposed around the light-emitting elements is required to have light resistance because it is exposed to strong light in the vicinity of the light-emitting elements. For this reason, many silicone resins which are more excellent in light resistance than an epoxy resin are used. However, the silicone resin has a problem that the linear expansion coefficient is larger than that of the epoxy resin. The linear expansion coefficient of epoxy resin is about 30 ppm / K to 40 ppm / K, while that of silicone resin is about 250 ppm / K. For this reason, when silicone resin is used as the underfill material, the thermal expansion becomes significant, and a large thermal stress is applied between the light emitting element and the submount substrate due to thermal shock such as reflow when mounted on the support, and the bump bonding portion. There was a problem of destroying.

Therefore, in the light emitting device according to the present embodiment, such an underfill material is eliminated, and a buffer layer 32 that is an air layer is intentionally provided between the light emitting device 10 and the submount substrate 20 to expand. The stress caused by the deformation is relaxed by the buffer layer 32 to reduce the risk of peeling due to such thermal expansion. In addition, since the process of filling the underfill resin can be reduced, the material cost can be reduced, and an operation of making a vacuum or the like is not necessary, and the operation can be greatly simplified.
(Coating layer 40)

  On the other hand, the periphery of the light emitting element 10 is covered with a covering layer 40. The covering layer 40 is made of resin. When the coating layer 40 is formed, a part of the resin enters between the light emitting element 10 and the submount substrate 20 to form the spacer layer 42 at the end. As a result, a region defined by the spacer layer 42 located at the end portion between the light emitting element 10 and the submount substrate 20 becomes the buffer layer 32.

  In forming the buffer layer 32, it is necessary to prevent the covering layer 40 covering the periphery of the light emitting element 10 from entering a large amount between the lower surface of the light emitting element 10, that is, between the light emitting element 10 and the submount substrate 20. Become. If the coating layer 40 is to be formed by conventional vacuum printing, the resin spreads over the entire lower surface of the light emitting element, and a buffer layer cannot be formed. Therefore, in this embodiment, atmospheric printing at normal pressure is performed.

The resin constituting the coating layer 40 is excellent in light resistance such as a silicone resin, an epoxy resin, an acrylic resin, a urea resin, a fluororesin, and an imide resin such as glass resin and silica gel, which are excellent in light resistance and translucency. Inorganic materials can be used. In this embodiment, a silicone resin having excellent light resistance is used. In addition, a thermosetting resin is used so that the resin does not melt due to heat during the manufacturing process. Further, various fillers such as aluminum nitride, aluminum oxide and a composite mixture thereof may be mixed in order to relieve the thermal stress of the resin.
(Resin material)

The covering layer 40 is provided as a phosphor-containing layer, a lens, a light emitting element protective layer, and the like. In the present embodiment, the resin material is constituted by a cured product of a curable silicone resin containing the following components (a) to (d).
(I) The following average composition formula (1):

R ¹ _a (OX) _b SiO _{(4-ab) / 2} (1)

(Wherein R ¹ is independently an alkyl group having 1 to 6 carbon atoms, an alkenyl group, or an aryl group, and X is independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkenyl group. , An alkoxyalkyl group or an acyl group, a is a number from 1.05 to 1.5, b is a number satisfying 0 <b <2, provided that a + b satisfies 1.05 <a + b <2. An organopolysiloxane having a polystyrene equivalent weight average molecular weight of 5 × 10 ³ or more,
(B) a condensation catalyst,
(C) Solvent and (d) Fine powder inorganic filler

Each component of these compositions will be described in detail below. In the following description, room temperature means 24 ± 2 ° C. unless otherwise specified.
((I) Organopolysiloxane)

The organopolysiloxane as component (a) is represented by the above average composition formula (1) and has a polystyrene-equivalent weight average molecular weight of 5 × 10 ³ or more.

In the average composition formula (1), examples of the alkyl group represented by R ¹ include a methyl group, an ethyl group, a propyl group, and a butyl group. Examples of the alkenyl group include a vinyl group and an allyl group. Examples of the aryl group include a phenyl group. Among these, a cured product is excellent in heat resistance, ultraviolet resistance and the like, and therefore, R ¹ is preferably a methyl group.

  Examples of the alkyl group represented by X include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, and an isobutyl group. Examples of alkenyl groups include vinyl groups. Examples of the alkoxyalkyl group include a methoxyethyl group, an ethoxyethyl group, and a butoxyethyl group. Examples of the acyl group include an acetyl group and a propionyl group. Among these, as X, a hydrogen atom, a methyl group, and an isobutyl group are preferable.

  a is preferably a number of 1.15 to 1.25, b is 0.01 ≦ b <1.4, particularly 0.01 ≦ b ≦ 1.0, especially O.D. It is preferable that the number satisfies 05 ≦ b ≦ 0.3. When a is less than 1.05, the obtained cured product is easily cracked, and when it exceeds 1.5, the cured product tends to be brittle with no toughness, heat resistance, and ultraviolet resistance. May be inferior. When b is 0, it may be inferior in the adhesiveness with respect to a base material, and when two or more, hardened | cured material may not be obtained. Further, a + b is a number that preferably satisfies 1.06 ≦ a + b ≦ 1.8, more preferably 1.1 ≦ a + b ≦ 1.7.

In addition, since the organopolysiloxane of this component is more excellent in heat resistance of the cured product, the ratio (mass basis) of R ¹ typified by methyl group or the like in the organopolysiloxane is usually 32. It is preferable to set it as mass% or less, Preferably 15-32 mass%, Especially 20-32 mass%, Especially 25-31 mass% is preferable. When the ratio of R ¹ is too small, the film formability and the crack resistance of the film may be inferior.

The organopolysiloxane of this component has the following general formula (2): SiR ¹ _c (OR ² ) _4-c (2) (wherein R ¹ is independently as described above, and R ² is independently And the same as those except for a hydrogen atom in X, and c is an integer of 1 to 3), or by hydrolyzing and condensing the silane compound represented by formula (2) And an alkyl silicate represented by the following general formula (3): Si (OR ² ) ₄ (3) (wherein R ² is independently the same as defined above) and / or It can be obtained by co-hydrolyzing and condensing the alkyl silicate polycondensate (alkyl polysilicate) (hereinafter referred to as “alkyl (poly) silicate”).

  These silane compounds and alkyl (poly) silicates may be used alone or in combination of two or more.

  Examples of the silane compound represented by the general formula (2) include methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, and dimethyldimethoxysilane. Dimethyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, methylphenyldimethoxysilane, methylphenyldiethoxysilane, and the like, preferably methyltrimethoxysilane and dimethyldimethoxysilane. These silane compounds may be used alone or in combination of two or more.

  Examples of the alkyl silicate represented by the general formula (3) include tetraalkoxysilanes such as tetramethoxysilane, tetraethoxysilane, tetraisopropyloxysilane, and the like, and polycondensates (alkylpolysilicates) of the alkylsilicate. Examples thereof include methyl polysilicate and ethyl polysilicate. These alkyl (poly) silicates may be used alone or in combination of two or more.

  Among these, since the resulting cured product is excellent in crack resistance and heat resistance, the organopolysiloxane of this component is composed of 50 to 95 mol% of alkyltrialkoxysilane such as methyltrimethoxysilane and dimethyldimethoxysilane. Are preferably composed of 50 to 5 mol% of a dialkyldialkoxysilane such as 75 to 85 mol% of an alkyltrialkoxysilane such as methyltrimethoxysilane and 25 to 15 mol% of a dialkyldialkoxysilane such as dimethyldimethoxysilane. Is more preferable.

  In a preferred embodiment, the organopolysiloxane of this component can be obtained by hydrolyzing and condensing the silane compound, or by cohydrolyzing and condensing the silane compound and an alkyl (poly) silicate. Although the method is not particularly limited, for example, the following conditions can be applied.

  The silane compound and alkyl (poly) silicate are usually preferably used after being dissolved in an organic solvent such as alcohols, ketones, esters, cellosolves, and aromatic compounds. Specifically, for example, alcohols such as methanol, ethanol, isopropyl alcohol, isobutyl alcohol, n-butanol, and 2-butanol are preferable, and the resulting composition has excellent curability and toughness of the cured product. Therefore, isobutyl alcohol is more preferable.

  Furthermore, the silane compound and alkyl (poly) silicate are preferably subjected to hydrolysis and condensation in combination with an acid catalyst such as acetic acid, hydrochloric acid or sulfuric acid. The amount of water added in the hydrolysis and condensation is usually 0.9 to 1.5 mol with respect to the total amount of alkoxy groups in the silane compound or the silane compound alkyl (poly) silicate. Yes, preferably 1.0 to 1.2 mol. When this compounding quantity satisfies the range of 0.9 to 1.5 mol, the composition has excellent workability, and the cured product has excellent toughness.

The weight average molecular weight in terms of polystyrene of the organopolysiloxane of this component is preferably 5 × 10 ³ or more from the viewpoint of handling, considering the pot life from the viewpoint of handling. Is required, preferably 5 × 10 ^{3 to} 3 × 10 ⁶ , particularly preferably 1 × 10 ⁴ to 1 × 10 ⁵ . When this molecular weight is less than 5 × 10 ³ , cracks are likely to occur when the resulting composition is cured. In addition, when this molecular weight is too large, this composition is easily gelled and the workability may be inferior.

  The aging temperature is preferably 0 to 40 ° C., more preferably room temperature. When this aging temperature is 0 to 40 ° C., the organopolysiloxane of this component has a ladder-like structure, so that the resulting cured product has excellent crack resistance.

The (a) component organopolysiloxane may be used alone or in combination of two or more.
((B) condensation catalyst)

  The condensation catalyst as component (b) is a component required for curing the organopolysiloxane as component (a). Although it does not specifically limit as a condensation catalyst, Since it is excellent in stability of the said organopolysiloxane, the hardness of hardened | cured material, UV resistance, etc., an organometallic catalyst is normally used. Examples of the organometallic catalyst include those containing atoms such as zinc, aluminum, titanium, tin, and cobalt, and those containing zinc, aluminum, and titanium atoms are preferable. Specific examples thereof include organic acid zinc, Lewis acid catalyst, organic aluminum compound, organic titanium compound and the like, and more specifically, for example, zinc octylate, zinc benzoate, zinc p-tert-butylbenzoate. , Zinc laurate, zinc stearate, aluminum chloride, aluminum perchlorate, aluminum phosphate, aluminum triisopropoxide, aluminum acetylacetonate, aluminum butoxybisethyl acetoacetate, tetrabutyl titanate, tetraisopropyl titanate, tin octylate , Cobalt naphthenate, tin naphthenate and the like, preferably zinc octylate.

(B) The compounding amount of component is usually 0.05 to 10 parts by mass with respect to 100 parts by mass of component (a), and the resulting composition is excellent in curability and stability. Preferably it is 0.1-5 mass parts. The (b) component condensation catalyst may be used alone or in combination of two or more.
((C) solvent)

  The solvent which is the component (c) is required particularly for improving the moldability of the cured product when the composition is screen-printed. The solvent is not particularly limited, but the boiling point is preferably 64 ° C or higher, more preferably 70 to 230 ° C, and particularly preferably 80 to 200 ° C. When the above range is satisfied, when the screen printing is performed, the composition or the cured product is free from bubbles (voids) due to bubbles and the surface whitening phenomenon is eliminated, so that a good molded product can be obtained.

  Examples of the solvent for this component include hydrocarbon solvents such as benzene, toluene and xylene; ether solvents such as tetrahydrofuran, 1,4-dioxane and diethyl ether; ketone solvents such as methyl ethyl ketone; chloroform, methylene chloride, 1 Halogen solvents such as 1,2-dichloroethane; alcohol solvents such as methanol, ethanol, isopropyl alcohol and isobutyl alcohol; organic solvents having a boiling point of less than 150 ° C. such as octamethylcyclotetrasiloxane and hexamethyldisiloxane, cellosolve acetate, Examples include organic solvents having a boiling point of 150 ° C. or higher, such as cyclohexanone, butyl cellosolve, methyl carbitol, carbitol, butyl carbitol, diethyl carbitol, cyclohexanol, diglyme, and triglyme. , Preferably, xylene, isobutyl alcohol, diglyme, and triglyme.

  These organic solvents may be used alone or in combination of two or more. However, since the leveling property of the coating surface of the composition is improved, it is preferable to use two or more in combination. Furthermore, it is particularly preferable to contain at least one organic solvent having a boiling point of 150 ° C. or higher because the composition is cured well during screen printing of the composition and a cured product having excellent workability can be obtained. In particular, in this component, the organic solvent having a boiling point of 150 ° C. or higher is preferably 5 to 30% by mass, more preferably 7 to 20% by mass, and further preferably 8 to 15% by mass. .

(C) Although the compounding quantity of a component is not specifically limited, Preferably it is 233 mass parts or less with respect to 100 mass parts of said (I) component, More preferably, it is 10-100 mass parts, Most preferably, it is 20-80 mass parts. It is. That is, the content of the component (a) relative to the sum of the components (a) and (c) is preferably 30% by mass or more, more preferably 50 to 91% by mass, and particularly preferably 55 to 83% by mass. When such a range is satisfied, the moldability of the cured product becomes better, and the thickness of the cured product is typically 10 μm to 3 mm, more typically 100 μm to 3 mm in a dry state. It becomes easy to process.
((D) Fine powder inorganic filler)

  The fine powder inorganic filler as component (d) imparts thixotropy necessary for screen printing to the composition. Further, by blending the inorganic filler, the light scattering of the cured product (for example, low birefringence) and the fluidity of the composition are in an appropriate range, or the material using the composition has high strength. There is an effect such as.

Although the specific surface area (BET specific surface area) of the fine powder inorganic filler by the BET method is not particularly limited, for example, when the composition is used for screen printing, it is 100 m ² / g or more (usually 100 to 400 m ² / is preferably g), more preferably 180 m ² / g or more, and particularly preferably 200~350m ² / g. If this range is satisfied, good thixotropy can be obtained for maintaining moldability, so that the blending amount of this component can be reduced.

  The inorganic filler constituting the fine powder inorganic filler is not particularly limited. For example, silica, alumina, aluminum hydroxide, titanium oxide, bengara, calcium carbonate, magnesium carbonate, aluminum nitride, magnesium oxide, zirconium oxide, and nitride Examples thereof include boron and silicon nitride. Generally, silica is suitably used because the particle size, purity and the like are appropriate.

  The silica, that is, fine powder silica, may be a known one, and may be wet silica or dry silica. Specific examples thereof include precipitated silica, silica xerogel, fumed silica, fused silica, crystalline silica, or the surface of which is hydrophobized with an organic silyl group. Examples of these commercial products include Aerosil (manufactured by Nippon Aerosil Co., Ltd.), Nipsil (manufactured by Nippon Silica Co., Ltd.), Cabosil (manufactured by Cabot Corporation of the United States), Santo Cell (manufactured by Monsanto Corporation of the United States) Can be mentioned.

  (D) Although the compounding quantity of a component is not specifically limited, Preferably it is 5-40 mass parts with respect to 100 mass parts of said (I) component, More preferably, it is 15-25 mass parts, Most preferably, it is 18-20 mass. Part. When this range is satisfied, the composition not only has good workability but also has sufficient thixotropy necessary for screen printing.

(D) The fine powder inorganic filler of the component may be used alone or in combination of two or more.
(Other ingredients)

In addition to the above-mentioned components (A) to (D), other components can be added to the present composition as long as the effects and effects of the present invention are not impaired. Other components may be used alone or in combination of two or more.
(Wavelength conversion layer)

By mixing the light-transmitting resin with a wavelength conversion member such as a fluorescent material that emits fluorescence when excited by the light of the light-emitting element 10, the light of the light-emitting element 10 is converted into light of a different wavelength. And the color-mixed light of the light converted in wavelength by the wavelength conversion member can be taken out to the outside. As the wavelength conversion member, the phosphor 96 can be preferably used.
(Phosphor 96)

The phosphor 96 converts visible light or ultraviolet light emitted from the light emitting element 10 into another emission wavelength. For example, it is excited by light emitted from the semiconductor light emitting layer of the LED and emits light. Preferred phosphors include nitrides such as YAG-based and alkaline earth silicon nitride phosphors, and oxynitride-based phosphors such as alkaline earth silicon oxynitride phosphors. In the present embodiment, a phosphor that is excited by ultraviolet light and generates light of a predetermined color is used as the phosphor. Specifically, the following can be used.
(1) Ca ₁₀ (PO ₄ ) ₆ FCl: Sb, Mn
(2) M ₅ (PO ₄ ) ₃ Cl: Eu (where M is at least one selected from Sr, Ca, Ba, Mg)
(3) BaMg ₂ Al ₁₆ O ₂₇ : Eu
(4) BaMg ₂ Al ₁₆ O ₂₇ : Eu, Mn
(5) 3.5MgO.0.5MgF ₂ .GeO ₂ : Mn
(6) Y ₂ O ₂ S: Eu
(7) Mg ₆ As ₂ O ₁₁ : Mn
(8) Sr ₄ Al ₁₄ O ₂₅ : Eu
(9) (Zn, Cd) S: Cu
(10) SrAl ₂ O ₄ : Eu
(11) Ca ₁₀ (PO ₄ ) ₆ ClBr: Mn, Eu
(12) Zn ₂ GeO ₄ : Mn
(13) Gd ₂ O ₂ S: Eu
(14) La ₂ O ₂ S: Eu
(15) Ca ₂ Si ₅ N ₈ : Eu
(16) Sr ₂ Si ₅ N ₈ : Eu
(17) SrSi ₂ O ₂ N ₂ : Eu
(18) BaSi ₂ O ₂ N ₂ : Eu

In addition to the above, it goes without saying that a YAG phosphor that is a rare earth aluminate represented by (Y, Gd) ₃ (Al, Ga) ₅ O ₁₂ : Ce or the like that emits light in the yellow region can be used.

  When the light emitted from the LED chip and the light emitted from the phosphor are in a complementary color relationship or the like, white light can be emitted by mixing each light. Specifically, the light emitted from the LED chip and the phosphor light excited and emitted thereby correspond to the three primary colors of light (red, green, and blue), or the blue light emitted from the LED chip. The light and the yellow light of the fluorescent substance excited and emitted by it are mentioned. In particular, when using ultraviolet light, the emission color of the phosphor excited and emitted by the ultraviolet light can be used independently, so it is possible to realize light emitting devices of various intermediate colors such as blue-green, yellow, red and pastel colors for signals. Is possible.

  The emission color of the light-emitting device can be adjusted in various ways such as the ratio of phosphors to various binders that work as binders for phosphors and phosphors, glass, and other inorganic binder members, fillers, sedimentation time of phosphors, phosphor shapes, etc. Further, by selecting the light emission wavelength of the LED chip, it is possible to provide an arbitrary white color tone such as a light bulb color. It is preferable that the light from the LED chip and the light from the phosphor efficiently pass through the mold member outside the light emitting device.

Representative phosphors include cadmium zinc sulfide attached with copper and YAG phosphor attached with cerium. In particular, at the time of high luminance and long-term use _{(Re 1-x Sm x)} 3 (Al 1-y Ga y) 5 O 12: Ce (0 ≦ x <1,0 ≦ y ≦ 1, where, Re Is at least one element selected from the group consisting of Y, Gd, La, and Lu.

_{(Re 1-x Sm x)} 3 (Al 1-y Ga y) 5 O 12: Ce phosphor, for garnet structure, heat, resistant to light and moisture, the peak of the excitation spectrum be the 470nm near the like Can do. In addition, the emission peak is in the vicinity of 530 nm, and a broad emission spectrum that extends to 720 nm can be provided.

In the light emitting device according to the embodiment of the present invention, the phosphor may be a mixture of two or more phosphors. That, Al, Ga, Y, La , the content of Lu and Gd and Sm are two or more kinds of _{(Re 1-x Sm x)} 3 (Al 1-y Ga y) 5 O 12: mixed Ce phosphor Thus, RGB wavelength components can be increased. Further, it is possible to increase the reddish component by using a nitride phosphor having yellow to red light emission, and to realize illumination with high average color rendering index Ra, light bulb color LED, and the like. Specifically, by adjusting the amount of phosphors having different chromaticity points on the CIE chromaticity diagram according to the light emission wavelength of the light emitting device, the phosphors are connected with each other on the chromaticity diagram. Any point can be made to emit light.

  Such a phosphor can be dispersed in a gas phase or a liquid phase and released uniformly. The phosphor in the gas phase or liquid phase is precipitated by its own weight. In particular, in the liquid phase, by allowing the suspension to stand, a film having a more uniform phosphor can be formed. A desired amount of phosphor can be formed by repeating a plurality of times as desired.

  Two or more kinds of the phosphors formed as described above may exist in the light emitting layer composed of one layer on the surface of the light emitting device, or one kind or two kinds or more each in the light emitting layer composed of two layers. May be present. In this way, white light is obtained by mixing colors of light from different phosphors. In this case, it is preferable that the average particle diameters and shapes of the phosphors are similar in order to better mix the light emitted from the phosphors and reduce color unevenness. In addition, the light emitting layer can be formed in consideration of sedimentation characteristics depending on the shape. Examples of a method for forming a light emitting layer that is hardly affected by the sedimentation characteristics include a spray method, a screen printing method, and a potting method. In the present embodiment, the inorganic binder has an effective solid component of 1% to 80%, and the viscosity can be adjusted over a wide range from 1 cps to 5000 cps, and the thixotropy can be adjusted. We can cope with method. The weight ratio of the filler and the inorganic binder is preferably in the range of 0.05 to 30 as described above, and the binding force is increased by adjusting the blending amount and particle size of the filler.

The phosphor used in the present embodiment is a combination of a YAG phosphor and a phosphor capable of emitting red light, particularly a nitride phosphor such as an alkaline earth silicon nitride phosphor. You can also These YAG phosphors and phosphors may be mixed and contained in the light emitting layer, or may be separately contained in the light emitting layer composed of a plurality of layers.
(Translucent resin)

  The fluorescent material is preferably dispersed uniformly in the light-transmitting resin. Thereby, wavelength conversion can be performed uniformly regardless of the portion of the wavelength conversion layer, and uniform color mixture light with no unevenness can be obtained.

  Further, aluminum oxide, barium oxide, barium titanate, silicon oxide, or the like can be contained in the light-transmitting resin for the purpose of diffusing light from the light-emitting element. Similarly, various colorants can be added in order to have a filter effect of cutting unnecessary wavelengths from extraneous light and light emitting elements.

The material of the light-transmitting resin is not particularly limited as long as it is light-transmitting. Silicone resin, epoxy resin, urea resin, fluororesin, and a hybrid resin including at least one of those resins are excellent in weather resistance. Resin can be used. Further, the light-transmitting resin is not limited to an organic material, and an inorganic material having excellent light resistance such as glass and silica gel can also be used. In the present embodiment, the translucent resin can be added to any member such as a viscosity extender, a light diffusing agent, a pigment, a fluorescent substance, and the like depending on the intended use. Examples of the light diffusing agent include barium titanate, titanium oxide, aluminum oxide, silicon oxide, silicon dioxide, heavy calcium carbonate, light calcium carbonate, and a mixture containing at least one of them. Furthermore, a lens effect can be provided by making the light emitting surface side of the translucent resin have a desired shape, and light emitted from the light emitting element chip can be focused. In addition, when a light receiving element is used as a semiconductor element, the sensitivity of the light receiving device can be improved by condensing light that passes through the translucent resin and enters the light receiving element in the direction of the light receiving element. Is possible. Specifically, a convex lens shape, a concave lens shape, an elliptical shape as viewed from the light emission observation surface, or a shape obtained by combining a plurality of them can be used.
(Spacer layer 42)

  The spacer layer 42 is not provided separately from the coating layer 40, but is formed at the same time as the coating layer 40 because part of the resin enters between the light emitting element 10 and the submount substrate 20 when the coating layer 40 is formed. In this way, the covering layer 40 and the spacer layer 42 are not formed as separate members, but are formed integrally, thereby reducing the number of processes and increasing the strength by completely covering the periphery of the light emitting element 10. It is also possible to improve the adhesion. In addition, the flow characteristics of the resin are adjusted, and the spacer layer 42 is configured so that only a part of the resin goes around from the lower side of the side surface of the light emitting element 10. That is, the flow characteristics are adjusted so that the resin penetrates only near the end of the space between the light emitting element 10 and the submount substrate 20 and does not penetrate further. Furthermore, in addition to the adjustment of the flow characteristics, the penetration amount of the resin can also be adjusted by adjusting the standing time after applying the resin by stencil printing. As described above, according to the present embodiment, the buffer layer 32 and the spacer layer 42 can be formed at the same time only by adjusting the flow characteristics of the resin and the leaving time without preparing a dedicated jig or member. Therefore, the manufacturing process can be simplified.

  In addition, by providing the spacer layer 42 around the buffer layer 32, that is, only at the end portion of the light emitting element 10, a secondary advantage that the deformation stress of the light emitting element 10 can be opposed is obtained. That is, when using an LED or the like obtained by epitaxially growing a nitride compound semiconductor layer such as gallium nitride grown on a sapphire substrate as the light emitting element 10, from the difference in thermal stress between the sapphire substrate and the nitride semiconductor layer, The substrate is warped. When the light emitting element 10 is flip-chip mounted, as shown in FIG. 4, both ends of the light emitting element 10 are positioned away from the submount substrate 20 rather than the center. On the other hand, when the submount substrate 20 is placed under a high temperature due to reflow or the like, the sapphire substrate tends to return to the original state due to thermal history, that is, in a direction in which both ends of the light emitting element 10 approach the submount substrate 20. Stress will work. As a result, in the bump 30 bonding between the light emitting element 10 and the submount substrate 20, the bump 30 on the end side is pressed and the bump 30 on the center side is relatively lifted, resulting in a peeling force. It will be. On the other hand, since the light emitting device according to the present embodiment is provided with the spacer layer 42 around the buffer layer 32, that is, at the end of the light emitting element 10, the spacer layer 42 tends to expand due to heat, and the deformation stress of the light emitting element 10. Acts as a resistance against As a result, the thermal history of the sapphire substrate is suppressed, the force with which the light emitting element 10 peels from the submount substrate 20 is weakened, and the adhesive force therebetween is maintained. In addition, the spacer layer 42 located at the end of the light emitting element 10 also serves to reinforce the adhesive force between the light emitting element 10 and the submount substrate 20. Thus, the thermal stress is relieved not only by the buffer layer 32 but also by the spacer layer 42 provided around the buffer layer 32, and can contribute to maintenance and strengthening of the adhesive force.

  In the spacer layer, the area ratio between the buffer layer and the spacer layer is preferably set to 9: 1 to 5: 5. It was confirmed by experiments that a sufficient mechanical strength of bonding can be obtained by forming the spacer layer adjusted to this range.

Examples of the flow characteristics include viscosity and thixotropy. Thixotropic is called thixotropy (tactile denaturation), which means that the viscosity decreases when stress is applied, such as stirring and vibration, and the viscosity increases when left standing. These viscosity and thixotropy are set according to the type of resin used, the size of the light emitting element 10, the thickness of the coating layer 40, the size of the gap between the light emitting element 10 and the submount substrate 20, and the like. For example, when using a silicone resin, the viscosity at 23 ° C. is set to 1 × 10 Pa · s to 1 × 10 ⁵ Pa · s, preferably 50 Pa · s to 2000 Pa · s, more preferably 100 Pa · s to 1000 Pa · s. Set to. The thixotropic coefficient is set to 1.0 to 15.0, preferably 3.0 to 9.0, and more preferably 4.0 to 8.0. Furthermore, the amount of penetration of the resin can also be adjusted by adjusting the standing time until the resin is thermally cured after stencil printing. The standing time is set according to the above-described flow characteristics such as viscosity and thixotropy, and is, for example, about 0.5 to 120 minutes, preferably about 5 to 30 minutes.

  Thus, in the present embodiment, the underfill resin is basically not used, and the buffer layer 32 of the air layer is formed. Accordingly, even when a silicone resin having a large linear expansion coefficient is used for the coating layer 40, such resin is almost eliminated from between the light emitting element 10 and the submount substrate 20. It is possible to avoid a situation in which the thermal stress is applied to the bump 30 and the bump 30 joint is damaged. As a result, it is possible to apply reflow or the like to the light emitting device, and an easy-to-use light emitting device can be realized.

  On the other hand, instead of completely removing the resin from between the light emitting element 10 and the submount substrate 20, the spacer layer 42 can be formed by intentionally leaving the resin at the end. It can be used in combination as a reinforcing material that resists thermal deformation on the light emitting element 10 side while improving adhesion and adhesion to the submount substrate 20.

  Further, by adjusting the flow characteristics of the resin, only a part of the resin can enter between the light emitting element 10 and the submount substrate 20. Accordingly, the resin layer can be partially penetrated to form the spacer layer 42 without providing a member such as a dam or a protective wall for preventing the resin from entering, and at the same time, the portion without the spacer layer 42 can be used as the buffer layer 32. As described above, the present embodiment, in which the spacer layer 42 and the buffer layer 32 can be formed at the same time only by adjusting the flow characteristics of the resin without using a member such as a mold, has a great merit that the manufacturing process is extremely easy. is there.

Further, the coating layer may be applied not only around the light emitting element but also on the surface of the submount substrate 20B as shown in FIG. In the example of FIG. 5, the coating layer 40B covering the side surface of the light emitting element 10B wraps around the back surface of the light emitting element 10B to form the spacer layer 42B, while extending on the opposite side along the surface of the submount substrate 20B. An extension layer 44B is formed. As a result, the covering layer 40B, which is a resin layer, is brought into close contact with the submount substrate 20B in a wider area, thereby improving the adhesive force.
(Stencil printing)

  In order to apply the resin to the light emitting element 10 to form the coating layer 40, stencil printing using a stencil (mask) can be used. For example, screen printing for applying a resin by running a squeegee S on the mask is performed. The amount of resin penetration can also be adjusted by adjusting the conditions during printing. That is, the amount of resin penetration can be adjusted by adjusting the moving speed of the squeegee S and the angle with the mask according to the type of resin used.

FIG. 6 shows a procedure for forming a coating layer around the light emitting element 10 by screen printing. First, as shown in FIG. 6A, an LED chip as a light emitting element 10 is flip-chip mounted on the submount substrate 20 via bumps. Next, as shown in FIG. 6B, the upper surface of the submount substrate 20 is covered with a metal mask. The mask has a through-opening region, and the mask is placed on the submount substrate 20 so that the LED is positioned substantially at the center of the opening region. Further, a resin containing a fluorescent material is supplied to the opening region. Here, about 5% by mass of Ce-activated YAG phosphor is mixed with 2% CTU guanamine resin as an organic diffusing material as an inorganic phosphor that emits yellowish visible fluorescence when irradiated with blue visible light. The prepared alicyclic epoxy resin composition (viscosity 10,000 cPS) is used as a printing ink for forming a coating layer and poured from above the mask as shown in FIG. In this state, the resin is extended with the squeegee S, and a coating layer is formed on the upper surface of the LED chip. In addition, when stencil printing is performed under reduced pressure during these steps, bubbles and the like can be defoamed very easily. After the coating layer is formed and cured, the mask is removed to form the coating layer on the upper and side surfaces of the LED chip as shown in FIG.
(Embodiment 2)

In this way, the submount structure in which the light emitting element 10 is mounted on the submount substrate 20 eliminates the underfill resin to avoid peeling due to thermal expansion, and is provided with a buffer layer 32, thereby preventing thermal deformation. Since it functions as a buffer region, thermal stress can be released. As a result, resistance to thermal shock is improved, and there is an advantage that it can be used without impairing reliability even in high-temperature processing. This is a great advantage when the submount substrate 20 is further used for processes such as reflow and eutectic. FIG. 7 shows a cross-sectional view of a light-emitting device 200 constituting the light-emitting device according to Embodiment 2 of the present invention. In the light emitting device 200 shown in this figure, a submount structure in which the light emitting element 10C is mounted on the submount substrate 20C is further mounted on the support 50. In this example, two light emitting elements 10C are mounted on one submount substrate 20C, and these two light emitting elements 10C are collectively covered with a coating layer 40C. Thus, the number of light-emitting elements mounted on the submount substrate can be changed as appropriate according to the application, the size of the light-emitting element / submount substrate, and the like. In addition, the coating layer may be coated for each light emitting element, or a plurality of light emitting elements may be collectively covered.
(Support 50)

The support 50 is a support such as a mount substrate or a package on which the submount substrate 20 is mounted by eutectic or reflow. The reflow is a technique for mounting the submount substrate 20 on the support 50 provided with the conductive pattern via solder. After the submount substrate is mounted on the support 50, the support 50 and the light emitting element 10 are electrically connected via a wire bond, a lead electrode, or the like. The support 50 thus wired is molded with an epoxy resin to obtain a light emitting device such as an LED element. The support 50 can be made of metal, ceramic, or the like depending on the application or purpose. In the example of FIG. 7, the submount substrate 20 is mounted on the support 50 via the eutectic layer 80 by eutectic bonding of Au—Sn at 300 ° C. Other eutectic materials for eutectic include silver paste and Ag-Sn. Alternatively, an adhesive material made of AuSi, SnAgBi, SnAgCu, SnAgBiCu, SnCu, SnBi, PbSn, In, or a combination thereof can be used. The eutectic material is selected according to the wettability and adhesion that vary depending on the material of the members to be joined. When the substrates are bonded with the eutectic material, the eutectic material may be formed on the surface side of one substrate and the metal film may be formed on the bonding surface of the other substrate. In this way, a metal film is formed on the surface of one substrate in contact with the eutectic material, and alloyed to obtain conductivity. Further, the eutectic layer 80 is not limited to a single layer, and may be composed of multiple layers.
(Method for manufacturing light emitting device)

Next, a method for manufacturing the light emitting device will be described with reference to FIG. First, as shown in FIG. 8A, bumps 30 are formed on a wafer 24 to be a submount substrate 20 according to a pattern for flip-chip mounting the light emitting elements 10. Next, as shown in FIG. 8B, the light emitting element 10 is flip-chip mounted through the bumps 30. In this example, two LED chips are mounted side by side in a region where one submount substrate 20 is formed. Further, screen printing is performed in FIG. Screen printing can be performed using a method substantially similar to that shown in FIG. That is, a metal mask is placed on the wafer 24, a resin constituting the coating layer 40 is applied, and the metal mask is spread with a squeegee. Then, after the resin is cured, the metal mask is removed, and dicing is performed as shown in FIG. Each of the cut submount substrates 20 is fixed on the support 50 through the eutectic layer 80 by eutectic die bonding as shown in FIG. Here, Au—Sn was used as eutectic solder, and eutectic was performed at about 290 ° C. Thereafter, as shown in FIG. 8E, the electrode of the submount substrate 20 and the electrode 90 of the support 50 are wired by wire bonding. Further, as shown in FIG. 8G, a resin lens 70 is fixed with an adhesive or the like so as to cover the outer periphery of the LED chip, thereby obtaining a light emitting device.
(Example)

  Next, in order to confirm the effectiveness of the present invention, Examples 1-4 and Comparative Example 1 were prototyped as samples in which the occupation ratio of the buffer layer and the spacer layer was changed, and a shear strength retention test was performed. Here, the amount of penetration of the resin (de facto underfill resin) between the light emitting element and the submount substrate is changed by adjusting the standing time after applying the silicone resin as the coating layer in stencil printing. Ten samples (Examples 1 to 4) were prepared, and the retention rate after applying stress by a shear test was measured. Further, as Comparative Example 1, a sample in which the resin was infiltrated into the entire surface with almost no buffer layer was prepared by using vacuum printing instead of adjusting the standing time. The optical micrograph of each device is shown in FIG. In this example, a light-emitting element dummy in which a bump surface is formed on a translucent sapphire substrate is used to image the state under the sapphire substrate so that the amount of the resin entering the lower surface of the light-emitting element can be confirmed. In each photograph, a boundary line indicating the amount of intrusion of the resin is schematically appended with a bold line. In FIG. 9, (a) shows Example 1, the standing time after stencil printing is 1 minute to 2 minutes, and the amount of resin penetration is extremely small. Further, (b) shows Example 2, in which the standing time after stencil printing is 10 minutes, and the amount of resin penetration is relatively small. Furthermore, (c) shows Example 3, in which the standing time is 60 minutes, and the amount of resin penetration is intermediate. Furthermore, (d) shows Example 4, in which the standing time is 120 minutes, and the amount of resin penetration is large. Finally, (e) performs vacuum printing as Comparative Example 1, and the resin completely penetrates the lower surface of the light emitting element.

  For these examples and comparative examples, a shear test was performed for each rough manufacturing process, and it was confirmed that the strength decreased. Here, a shear test was performed immediately after stencil printing, after resin curing, and after the sample was mounted on a support as a eutectic, and the retention rate (shear strength retention rate) of the sample that was not peeled was examined. Furthermore, the area ratio between the buffer layer and the spacer layer was also measured. This ratio is the ratio between the spacer layer and the resin that has entered here, and does not include bumps. The results are shown in Table 1.

  As shown in Table 1, immediately after stencil printing, all showed a high value of 90% or more regardless of the amount of resin. That is, since the resin is not yet cured at this point, there is no effect of inhibiting the bonding between the light emitting element and the submount substrate. Next, when comparing the strength after thermosetting the resin, the strength decreases slightly as the amount of resin increases. On the other hand, a great difference was observed in the strength change after the eutectic mounting on the support. In other words, it was confirmed that the strength decreased as the amount of the resin increased. In particular, in Comparative Example 1 in which the space between the submount substrate and the light emitting element was completely filled with resin, it was found that the bonding strength decreased by nearly 80% from the initial bonding strength after thermal shock. This tendency was almost the same as the decrease rate even when the bonding strength after printing was increased. On the other hand, in the example in which the amount of resin entering the space was suppressed, the rate of decrease from the initial bonding strength remained at about 20%. From this, it became clear that the decrease in the shear strength after eutectic thermal history becomes more remarkable as the amount of resin increases and the buffer layer becomes smaller. Moreover, even if the resin amount is the same, the shear strength decreases due to a thermal history such as eutectic. This tendency is particularly noticeable in Comparative Example 1 in which there is no buffer layer. On the other hand, in Example 1 in which the amount of intrusion of the resin is small and the buffer layer is secured, there is almost no decrease in strength due to thermal history, and the effect of resin curing. It was confirmed that has been resolved. Thus, the strength can be maintained by controlling the amount of resin, and damage due to thermal shock in the subsequent process can be reduced.

  Further, it was confirmed that the area ratio between the buffer layer and the spacer layer tended to decrease in strength as the buffer layer became smaller, that is, as the ratio of the spacer layer increased. In particular, the strength is relatively maintained up to about 1: 1 between the buffer layer and the spacer layer. However, when the spacer layer is larger than this, the strength is significantly reduced. Therefore, the area ratio between the buffer layer and the spacer layer is preferably in the range of about 9: 1 to 5: 5.

  INDUSTRIAL APPLICABILITY The light-emitting device and the method for manufacturing the light-emitting device according to the present invention can be suitably used for a surface-mounted LED that uses a submount substrate that is interposed when a semiconductor element such as an LED or LD is die-bonded to a support or the like. .

It is sectional drawing which shows the light-emitting device which concerns on Embodiment 1 of this invention. It is sectional drawing of the submount substrate and light emitting element which comprise the light-emitting device of FIG. It is a top view which shows the wafer in which the submount substrate was formed. In FIG. 2, it is sectional drawing explaining a mode that stress acts in the direction which returns curvature by the thermal history of a sapphire substrate. It is sectional drawing which shows the modification of the light-emitting device of FIG. It is sectional drawing which shows the procedure which forms a coating layer around a light emitting element by screen printing. It is sectional drawing which shows the light-emitting device which concerns on Embodiment 2 of this invention. It is a schematic diagram which shows the manufacturing method of a light-emitting device. It is an image figure which shows the optical microscope photograph of the sample which concerns on Examples 1-4 and the comparative example 1. FIG. It is sectional drawing explaining a mode that underfill resin thermally expands. It is sectional drawing explaining the state which the sapphire substrate warped. It is sectional drawing explaining the state in which the sapphire substrate of FIG. 11 was mounted in the submount substrate. It is sectional drawing explaining a mode that stress acts in the direction which returns curvature by the thermal history of a sapphire substrate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100, 200 ... Light-emitting device 10, 10B, 10C, 610 ... Light emitting element 12 ... Growth substrate 14 ... Semiconductor layer 20, 20B, 20C, 620 ... Submount substrate 21 ... Light emitting element mounting surface 22 ... Support body mounting surface 24 ... Wafer 30, 630, 630A, 630B ... Bump 32 ... Buffer layer 40, 40B, 40C ... Coating layer 42, 42B ... Spacer layer 44B ... Extension layer 50 ... Support 60 ... Underfill resin 70 ... Lens 80 ... Eutectic layer 90 ... Electrode 92 ... Wire 94 ... Electrode 96 ... Phosphor 612 ... Sapphire substrate 614 ... Gallium nitride compound semiconductor layer S ... Squeegee

Claims (12)

A light emitting element;
A submount substrate capable of flip-chip mounting the light emitting element on an upper surface via a conductive bonding material;
With the light emitting element mounted on a submount substrate, a resin coating layer covering the periphery of the light emitting element;
With
A buffer layer made of an air layer is formed in the space between the light emitting element and the submount substrate,
The resin forming the covering layer forms a spacer layer from the periphery of the light emitting element to an end of a space formed between the light emitting element and the submount substrate, and the covering layer and the spacer layer are It is formed integrally with the same member,
Furthermore, as a characteristic of the resin, when forming the coating layer, a part of the resin can enter between the light emitting element and the submount substrate from the side surface of the light emitting element to form a spacer layer at the end. A light emitting device characterized by being adjusted to the above. A light emitting element;
A submount substrate capable of flip-chip mounting the light emitting element on an upper surface via a conductive bonding material;
With the light emitting element mounted on a submount substrate, a resin coating layer covering the periphery of the light emitting element;
With
A buffer layer made of an air layer is formed in the space between the light emitting element and the submount substrate,
The resin forming the covering layer forms a spacer layer from the periphery of the light emitting element to an end of a space formed between the light emitting element and the submount substrate, and the covering layer and the spacer layer are It is formed integrally with the same member,
An area ratio of the buffer layer and the spacer layer provided in a space between the light emitting element and the submount substrate is 9: 1 to 5: 5. The light-emitting device according to claim 1 or 2,
A light-emitting device, wherein the light-emitting element is a semiconductor light-emitting element chip formed by epitaxial growth on a sapphire substrate. The light-emitting device according to any one of claims 1 to 3,
The light-emitting device, wherein the covering layer is made of a light-transmitting resin and is a wavelength conversion layer containing a fluorescent material that receives light emitted from the light-emitting element and converts the wavelength of the light. The light-emitting device according to any one of claims 1 to 4,
A light-emitting device, wherein the resin constituting the coating layer is a silicone resin. The light emitting device according to any one of claims 1 to 5, further comprising:
A support for mounting the submount substrate on the upper surface;
The light emitting device, wherein the submount substrate is mounted on the support through a eutectic layer. The light emitting device according to any one of claims 1 to 6,
The light emitting device, wherein the conductive bonding material is a bump. The light emitting device according to any one of claims 1 to 7,
A light emitting device characterized by adjusting the viscosity at 23 ° C. to 1 × 10 Pa · s to 1 × 10 ⁵ Pa · s and the thixotropic coefficient to 1.0 to 15.0 as flow characteristics of the resin. The light-emitting device according to any one of claims 1 to 8,
The resin is (i) the following average composition formula (1):
R ¹ _a (OX) _b SiO _{(4-ab) / 2} (1)
(Wherein R ¹ is independently an alkyl group having 1 to 6 carbon atoms, an alkenyl group, or an aryl group, and X is independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkenyl group. , An alkoxyalkyl group or an acyl group, a is a number from 1.05 to 1.5, b is a number satisfying 0 <b <2, provided that a + b satisfies 1.05 <a + b <2. An organopolysiloxane having a polystyrene equivalent weight average molecular weight of 5 × 10 ³ or more,
(B) a condensation catalyst,
(C) A light emitting device comprising a cured product of a curable silicone resin composition containing a solvent and (d) a fine powder inorganic filler. A method of manufacturing a light emitting device in which a light emitting element is flip-chip mounted on a submount substrate,
Flip chip mounting the light emitting element on the submount substrate via a conductive bonding material,
In a state where the light emitting element is mounted on the submount substrate, the upper surface and the side surface of the light emitting element are covered with resin, and the resin is applied from the end to the space formed between the light emitting element and the submount substrate. A step of applying a resin whose flow characteristics are adjusted so as to be able to enter a part by stencil printing;
By curing the resin, a coating layer covering the periphery of the light emitting element and a spacer layer positioned at an end of a space between the light emitting element and the submount substrate are integrally formed, and at the same time, the light emitting element and Forming a buffer layer made of an air layer between the submount substrate,
A method for manufacturing a light-emitting device, comprising: It is a manufacturing method of the light-emitting device according to claim 10,
A method for manufacturing a light emitting device, wherein the step of applying a resin by printing is performed by atmospheric printing. A method of manufacturing a light emitting device according to claim 10 or 11,
By controlling the time from the step of applying the resin by printing to the step of curing the resin, the amount of the resin entering from the end of the space formed between the light emitting element and the submount substrate can be adjusted. A method for manufacturing a light emitting device, comprising: