JP2017212273A - Method for manufacturing light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a light-emitting device, which is arranged so as to reduce a load on a light-emitting element when mounting the light-emitting element on a package.SOLUTION: A method for manufacturing a light-emitting device comprises the steps of: preparing a light-emitting element having an electrode on a bottom face; preparing a substrate with wiring on a top face; forming first bumps and second bumps thinner than the first bumps in thickness in an element placement region to put the light-emitting element on the top face of the substrate; and placing the light-emitting element on the first bumps and then, deforming the first bumps so as to put the light-emitting element in contact with the second bumps. The first bumps include: at least one center first bump to be disposed on a center portion of the element placement region; and at least three outer peripheral first bumps to be disposed at locations which are substantially identical to each other in the distance from the center of the element placement region.SELECTED DRAWING: Figure 1C

Description

  The present invention relates to a method for manufacturing a light emitting device.

  A light emitting device having a structure in which a semiconductor light emitting element (hereinafter also referred to as “light emitting element”) is flip-chip mounted using a bump is known (for example, Patent Documents 1 and 2). Such a light-emitting device is obtained by mounting a light-emitting element on a bump mounted on a package and bonding the light-emitting element by pressing the light-emitting element while applying ultrasonic waves. The number and arrangement of the bumps are selected according to the size and shape of the light emitting element, the wiring pattern of the package, and the like.

JP 2006-740007 A JP 2014-36080 A JP 2008-140868 A

  In order to improve heat dissipation, it is preferable that the number of bumps is large. However, when the number of bumps is large, the light emitting element may be overloaded.

The present embodiment includes the following configuration.
A step of preparing a light emitting element having an electrode on a lower surface, a step of preparing a substrate having a wiring on an upper surface, and an upper surface of the substrate, and a plurality of first mounting regions in an element mounting region on which the light emitting element is mounted A step of forming one bump and a second bump having a thickness smaller than that of the first bump, and a light emitting element is placed on the first bump, and then the first bump is brought into contact with the light emitting element. A step of deforming the bumps, and the first bump is disposed at a position where the distance from the center of the element mounting region is substantially equal to at least one central first bump disposed in the central portion of the element mounting region. And at least three outer peripheral first bumps. A method of manufacturing a light-emitting device.

  As described above, a manufacturing method in which a load applied to the light emitting element when the light emitting element is mounted on the package can be reduced.

FIG. 1A is a schematic perspective view illustrating a state in which a part of a light emitting device obtained by the method for manufacturing a light emitting device according to the embodiment is transparent. FIG. 1B is a schematic top view of the light emitting device of FIG. 1A. FIG. 1C is a schematic top view showing a state in which a part of the light emitting device of FIG. 1B is transparent. 1D is a schematic cross-sectional view taken along line AA in FIG. 1C. FIG. 2 is a schematic bottom view of a light-emitting element used in the method for manufacturing a light-emitting device. FIG. 3 is a schematic top view of a substrate used in the method for manufacturing a light emitting device. FIG. 4 is a schematic diagram for explaining the element mounting region. FIG. 5A is a schematic top view illustrating the method for manufacturing the light emitting device. 5B is a schematic cross-sectional view taken along line BB in FIG. 5A. FIG. 6B is a schematic top view illustrating the element mounting region. FIG. 6B is a schematic top view illustrating the element mounting region. FIG. 7A is a schematic top view for explaining the position of the bump in the element mounting region. FIG. 7B is a schematic top view for explaining the position of the bump in the element mounting region. FIG. 7C is a schematic top view illustrating the position of the bump in the element mounting area. FIG. 7D is a schematic top view for explaining the position of the bump in the element mounting region. FIG. 8 is a schematic cross-sectional view illustrating a method for manufacturing a light emitting device. FIG. 9 is a schematic cross-sectional view illustrating the method for manufacturing the light emitting device.

  A mode for carrying out the present invention will be described below with reference to the drawings. However, the form shown below illustrates the manufacturing method of the light-emitting device for materializing the technical idea of this invention, and this invention does not limit the manufacturing method of a light-emitting device below.

  Further, the present specification by no means specifies the member shown in the claims as the member of the embodiment. In particular, the dimensions, materials, shapes, relative arrangements, and the like of the components described in the embodiments are not intended to limit the present invention only to the embodiments unless specifically described. It should be noted that the size and positional relationship of the members shown in each drawing may be exaggerated for clarity of explanation. Furthermore, in the following description, the same name and symbol indicate the same or the same members, and detailed description thereof will be omitted as appropriate.

  1A to 1D show an example of a light emitting device 100 obtained by the method for manufacturing a light emitting device according to the embodiment. The light emitting device 100 mainly includes a substrate 20, a light emitting element 10, and a bump 30 that joins the substrate 20 and the light emitting element 10.

  The light emitting element 10 includes a stacked structure 11 including a semiconductor layer, and a first electrode 121 and a second electrode 122 as the electrodes 12. The first electrode 121 and the second electrode 122 are both provided on the lower surface (the surface on the side facing the substrate 20) of the multilayer structure 11. The first electrode 121 is disposed at the center of the lower surface of the multilayer structure 11, and the second electrode 122 is disposed at the outer peripheral portion of the lower surface of the multilayer structure 11.

  The first electrode 121 and the second electrode 122 of the light emitting element 10 are each connected to the wiring 22 of the substrate 20 via the bumps 30. The bump 30 includes a first bump 31 and a second bump 32. The first bump 31 is thicker than the second bump 32 before the light emitting element 10 and the substrate 20 are joined. In a state where the light emitting element 10 and the substrate 20 are bonded, the first bump 31 and the second bump 32 have the same thickness.

  The first bump 31 includes a central first bump 311 disposed in the central portion of the element mounting region R, and an outer peripheral first bump 312 provided in the outer peripheral portion of the element mounting region R. At least one central first bump 311 is disposed in the central portion of the element mounting region R. At least three outer peripheral first bumps 312 are arranged on the outer peripheral portion. Further, the outer peripheral first bump 312 is disposed at a position where the distance from the center of the element mounting region R is substantially equal. The “central part” and “outer peripheral part” of the element mounting region R will be described later.

  A method for manufacturing such a light emitting device 100 will be described below.

(Process for preparing light emitting element)
First, a light emitting element is prepared. FIG. 2 is a schematic bottom view showing an example of the light emitting device 10 having the electrode 12 on the bottom surface. As illustrated in FIG. 1D, the light emitting element 10 includes a stacked structure 11 including a semiconductor layer. A pair of electrodes 12 is provided on the lower surface of the laminated structure 11. As the electrode 12, a first electrode 121 and a second electrode 122 are provided. Here, the light emitting element 10 including the laminated structure 11 having a square bottom view, a rectangular first electrode 121 provided at the center thereof, and a second electrode 122 surrounding the first electrode 121 is illustrated. .

(Process for preparing a substrate with wiring on the top surface)
A substrate with wiring on the top surface is prepared. FIG. 3 is a schematic top view of the substrate 20 having the wiring 22 on the top surface. As illustrated in FIG. 1D, the substrate 20 includes an insulating base material 21 and a pair of wirings 22 provided on the upper surface and the lower surface of the base material 21. As the wiring 22, a first wiring 221 and a second wiring 222 are provided. Here, the substrate 20 whose top view is square is illustrated. In the substrate 20, a rectangular first wiring 221 is arranged at the approximate center of the upper surface of the substrate 20 in accordance with the shape of the electrode 12 of the light emitting element 10. Furthermore, a second wiring 222 arranged so as to surround the three sides of the first wiring 221 is provided.

  As shown in FIG. 1D, the first wiring 221 and the second wiring 222 electrically connect the upper surface wiring formed on the upper surface of the substrate, the lower surface wiring formed on the lower surface of the substrate, and the upper surface wiring and the lower surface wiring. And vias 23 to be connected to each other.

  The substrate 20 includes an element mounting region R. The element mounting area R indicates an area immediately below the light emitting element 10 and indicates an area including both the first wiring 221 and the second wiring 222. Here, since the element mounting region R in the case of using the square light emitting element 10 is illustrated, the square region indicated by the broken line in FIG. 3 is the element mounting region R, which indicates a virtual region. The element mounting region R is disposed at the center of the substrate 20.

  Here, the “central part” and the “outer peripheral part” of the element mounting region R will be described. The central part is an area where the central first bump is arranged, and the outer peripheral part is an area where the outer peripheral first bump is arranged. The central portion is a region including the center of the element mounting region, and the outer peripheral portion is a region disposed so as to surround the central portion. In the present specification, the central portion is defined as a portion that occupies 60% of the vertical side of the element mounting region and a portion that occupies 60% of the horizontal side of the element mounting region.

  FIG. 4 is a diagram showing the element mounting region R defined as described above. The element mounting region R includes 25 regions virtually divided into 5 rows × 5 columns, and of these, 16 regions R2 to R17 arranged on the outer periphery are outer peripheral portions, and this outer peripheral portion A region corresponding to nine sections surrounded by a central portion R1.

(Bump forming process)
Next, as shown in FIGS. 5A and 5B, a plurality of first bumps 31 </ b> A and second bumps 32 </ b> A that are thinner than the first bumps 31 </ b> A are formed in the element placement region R on the upper surface of the substrate 20. To do. The first bump and the second bump can be, for example, a ball bump, a plating bump, or the like.

  In the case of a ball bump, for example, it becomes a hemispherical or semi-elliptical bump. That is, as shown in FIG. 5B, the bump becomes a semi-circular or semi-elliptical bump whose center is high in a sectional view. When viewed from the top, the bumps are circular or elliptical as shown in FIG. 5A. In the case of plating bumps, the bumps are cylindrical, prismatic, truncated cone, and truncated pyramid. That is, it becomes a square or trapezoidal bump whose upper surface is substantially flat in a sectional view. Further, in a top view, it can be a circle, an ellipse, or a polygon such as a quadrangle.

  In the case of a ball bump, the order in which the first bump and the second bump are formed is not particularly limited. For example, the second bump can be formed after all the first bumps are formed in one element mounting region R. Alternatively, the first bump can be formed after all the second bumps are formed. Alternatively, they can be formed in the order in which they are arranged regardless of the first bump and the second bump. In the case of a ball bump, the size of the ball can be adjusted by controlling the conditions for forming the ball, such as spark time or voltage. Therefore, even when the first bumps and the second bumps are alternately or randomly formed, they can be formed without any particular problem.

  In the case of a plated bump, after forming a plated bump to be the first bump using a mask having an opening in a portion where the first bump is to be formed, an opening is formed in the portion where the first bump is covered and the second bump is to be formed. A plating bump to be the second bump can be formed using the mask having the same. It can also be formed in the reverse order. Alternatively, a part of the first bump and the second bump are formed by using a mask having an opening in a portion where the first bump and the second bump are to be formed, and then the second bump is covered and formed halfway. It is possible to form a first bump thicker than the second bump by further plating on the first bump.

  The first bump 31A is disposed at the outer peripheral portion at a position where the distance from the center of the element placement region R is substantially equal to at least one central first bump 311A disposed in the center portion R1 of the element placement region R. And at least three outer peripheral first bumps 312A.

  The central first bump 311A is provided in the central portion R1 of the element mounting region R. FIG. 5A shows an example in which the central first bump 311A is arranged at a position substantially coincident with the center C of the light emitting element. Further, since the first wiring 221 is disposed in the central portion R1 of the element mounting region R, the central first bump 311A is disposed on the first wiring 221.

  The outer peripheral first bump 312A is disposed on one of the outer peripheral portions R2 to R17 of the element mounting region R. Here, one outer peripheral first bump 312A is disposed at each of the four corners shown in FIG. 4, that is, four locations R2, R6, R10, and R14. The outer peripheral first bump 312A is disposed at a position where the distance from the center C of the element mounting region R is substantially equal. Here, since the central first bump 311A is located at the center C of the element mounting region R, the distance between the four outer peripheral first bumps 312A and the central first bump 311A is also substantially equal. In addition, since the second wiring 222 is disposed in the outer peripheral portions R2, R6, R10, and R14, the four external first bumps 312A are all disposed on the second wiring 222.

  The external first bump 312A is disposed at a position where the distance from the center C of the element mounting region R is substantially equal. However, the following conditions must be satisfied. 6A and 6B show examples of two regions Q1 and Q2 that are virtually partitioned by an arbitrary straight line passing through the center C of the element mounting region R. FIG. It is necessary that at least one external first bump is disposed in each of the two regions. FIG. 6A shows two regions virtually divided by a straight line passing through the center C and parallel to one side of the element mounting region R. In FIG. 6B, the straight line passing through the center C is not parallel to any side of the element mounting region R. As described above, it is necessary that at least one outer peripheral first bump is disposed in both of the two divided areas regardless of the angle of the straight line dividing the two areas.

  7A to 7D show an example in which one central first bump 311A and three outer peripheral first bumps 312A are arranged in the element placement region R. FIG. 7A to 7D, a diagram in which the central portion and the outer peripheral portion shown in FIG. 4 are divided into 25 parts by dotted lines, and four straight lines passing through the center C shown in FIG. The figure (Q2 is indicated by light ink) is divided and shown in an overlapping manner.

  In FIG. 7A, the central first bump 311A disposed in the central portion R1 is disposed at a position overlapping the center C of the element mounting region R. Therefore, the central first bump 311 is disposed across the two regions Q1 and Q2. Further, one outer peripheral first bump 312A is arranged for R5, one for R11, and one for R15. One outer peripheral first bump 312A is arranged on Q1, and two outer peripheral first bumps 312A are arranged on Q2. The three outer peripheral first bumps 312A are arranged at positions separated from the center C of the element placement region R by a distance L1. In FIG. 7A, the distance between the central first bump 311A and the three outer peripheral first bumps 312A is also equal. Thereby, the load applied to the central first bump 311A and the outer peripheral first bump 312A can be uniformly distributed.

  In FIG. 7B, the positions of the three outer peripheral first bumps 312A are the same as those in FIG. 7A. Accordingly, the distance between the center C of the element mounting region R and the outer peripheral first bump 312A is the same as that in FIG. 7A. 7B is different from FIG. 7A in that the center first bump 311A is disposed in the center portion R1 and at a position different from the center C of the element mounting region R. 7B is also different from FIG. 7A in that the central first bump 311A is arranged only in Q1. Therefore, the distance between the central first bump 311A and the three outer peripheral first bumps 312A is different from L3 longer than L2 and L2, and L4 longer than L3.

  In FIG. 7C, the central first bump 311A is arranged at the center C of the element placement region R in the same manner as in FIG. 7C. Three outer peripheral first bumps 312A are arranged for R3, one for R11, and one for R17. The distance L5 from the center C of the element mounting region R is the same. 7C differs from FIG. 7A in that two of the three outer peripheral first bumps 312A are arranged at Q1, and the other one is arranged at Q2.

  In FIG. 7D, the positions of the three outer peripheral first bumps 312A are the same as those in FIG. 7C. 7C differs from FIG. 7C in that the center first bump 311A is located at the center portion R1 and at Q2. 7A to 7C, the central first bump 311A is arranged in the virtual triangular region surrounded by the three external first bumps 312A, whereas in FIG. 7D, the central first bump 311A is the virtual triangle. It is located outside the area.

  As described above, the outer peripheral first bump can be disposed at any position within a range that satisfies the condition. As a preferable arrangement, for example, at least three outer peripheral first bumps are arranged at equal intervals. For example, in FIG. 7A, the three outer peripheral first bumps 312A are arranged at positions corresponding to the three vertices of the equilateral triangle. As described above, by equalizing the distance between the outer peripheral first bumps 312A, it is possible to easily distribute the load applied when the light emitting elements are joined.

  The first bump may be provided in addition to the central first bump and the outer peripheral first bump as described above. For example, as shown in FIG. 5A, four auxiliary first bumps 313A are provided in addition to one central first bump 311A and four outer peripheral first bumps 312A. The auxiliary first bump 313A can be arranged in consideration of the balance between the central first bump and the outer peripheral first bump.

  Further, it is preferable that at least one first bump is disposed on each of the first wiring and the second wiring. Depending on the electrode pattern of the light emitting element, for example, when it is difficult to provide the central first bump or the outer peripheral first bump in the first wiring, the auxiliary first bump may be arranged in the first wiring. it can.

  In the element mounting region R, in addition to the first bumps arranged as described above, a second bump having a thickness smaller than that of the first bump is arranged.

  As shown in FIG. 5A, the second bump 32A is arranged in the element placement region R on the wiring (first wiring 221 and second wiring 222). The second bump 32A is disposed in a region where the first bump 31A is not disposed so as to be separated from the first bump 31A. The number and position of the second bumps 32 </ b> A can be appropriately changed depending on the pattern of the wiring 22.

  As shown in FIG. 5B, the thickness H2 of the second bump 32A is thinner than the thickness H1 of the first bump 31A. For example, the thickness H2 of the second bump 32A can be about 20% to 80% of the thickness H1 of the first bump 31A.

  Further, as shown in FIG. 5A and the like, the diameter (maximum diameter) W1 of the first bump 31A is larger than the diameter (maximum diameter) W2 of the second bump 32A. That is, the first bump 31A shown in FIG. 5A is thicker and larger in diameter than the second bump 32A. In other words, the first bump 31A preferably has a larger volume than the second bump 32A.

  Further, the first bump 31A and the second bump 32A may have the same volume by making the diameter of the first bump 31A smaller than the diameter of the second bump 32A. Alternatively, the diameter of the first bump 31A and the diameter of the second bump 32A may be the same diameter.

(Step of placing a light emitting element on the first bump)
Next, a light emitting element is mounted on the first bump. As shown in FIG. 8, the electrode 12 of the light emitting element 10 is on the lower side, and this electrode 12 is in contact with the first bump 31A (center first bump 311A, outer peripheral first bump 312A, auxiliary first bump 313A). For example, the light emitting element 10 is mounted using a collet or the like. Since the first bump 31A and the second bump 32A have different thicknesses (heights), the light emitting element 10 and the second bump 32A are not in contact at this time.

(Process of deforming the first bump so that the second bump contacts the light emitting element)
Next, as shown in FIG. 9, the first bump is deformed so that the second bump contacts the light emitting element. In detail, while applying an ultrasonic wave to the light emitting element 10, it pressurizes and deform | transforms so that the 1st bump 31A may be crushed, and it is set as the 1st bump 31 thinner than the 1st bump 31A before a deformation | transformation. As a result, as shown in FIG. 9, both the first bump 31 </ b> A and the second bump 32 </ b> A come into contact with the light emitting element 10.

  As described above, by deforming only the first bumps that are some of the plurality of bumps arranged in the element mounting region, it is possible to reduce the load applied during bonding. Furthermore, the load can be further distributed by arranging the first bumps in a balanced manner at the center portion of the element mounting region and the outer peripheral portion.

  The second bump 32 </ b> A may not be deformed, but is preferably deformed and bonded to the light emitting element 10. For example, after the second bump 32A and the light emitting element 10 are in contact with each other, a part of the second bump 32A can be deformed by applying an ultrasonic wave and applying pressure. Thereby, the light emitting element 10 can be bonded with good adhesion by being bonded to both the deformed first bump 31 and the deformed second bump 32.

  Even when the second bump, which is thinner than the first bump, is deformed, a load is applied to the light emitting element. However, since the amount of deformation is small compared to the first bump, the load applied when the first bump is deformed is smaller. That is, when all the bumps are deformed, the load applied to the light emitting element as a whole can be reduced by making the bumps partly thinner than the load applied when using bumps having the same thickness. . Thereby, the light-emitting device excellent in heat dissipation can be obtained.

(Other processes)
In addition to the above steps, the following steps may be provided.
1) A step of forming a sealing member that covers the light emitting element 2) A step of forming a wavelength conversion member including a phosphor on the surface of the light emitting element, and then a sealing member that covers them 3) A protective element is formed Step 4) Step of Cutting Substrate One or more of these steps can be used, and the order thereof can be selected as appropriate.

  From the viewpoint of protecting the light emitting element, it is preferable to include the step 1). When a white light emitting device is used, it is preferable to include the step 2). In order to obtain a reliable light-emitting device, it is preferable to include the step 3). Moreover, when manufacturing a light emitting device, it is necessary to provide the process of 4) because it is often manufactured by using a plurality of substrates in the final stage. Many.

  Hereinafter, each member will be described in detail.

(Light emitting element)
As the light emitting element, a light emitting diode is preferably used. The stacked structure of the light emitting diode includes a semiconductor layer, for example, a nitride semiconductor such as InN, AlN, GaN, InGaN, AlGaN, InGaAlN, a III-V compound semiconductor, or a II-VI group compound semiconductor. It is done. These laminated structures include a light emitting layer. Moreover, the laminated structure may include a light-transmitting substrate. A sapphire is mentioned as a translucent board | substrate. The laminated structure may have a polygonal shape such as a triangle, a quadrangle, a pentagon, and a hexagon in a top view, or a shape in which some of these are missing. The materials for the first electrode and the second electrode are not particularly limited, and known materials can be used.

(bump)
The bump is a conductive member for electrically connecting the electrode of the light emitting element and the wiring of the substrate. For the bump, examples of the material of the bump include Au and Al, and Au is preferable.

(substrate)
A board | substrate is for arrange | positioning electronic components, such as a light emitting element and a protection element, and is provided with an insulating base material and electroconductive wiring. The shape of the substrate is not particularly limited. For example, the substrate preferably has a shape with a flat upper surface, such as a rectangular flat substrate having a thickness of about 300 μm to 500 μm. Examples of the substrate include glass epoxy resin and thermoplastic resin, and ceramics such as alumina and aluminum nitride.

  The wiring is used to apply a voltage from an external power source to an electronic component such as a light emitting element, and is provided on the upper surface and the lower surface of the substrate. Specifically, the wiring includes a first wiring connected to the first electrode of the light emitting element via the first bump, a second wiring connected to the second electrode of the light emitting element via the second bump, and Is provided. The first wiring and the second wiring include an upper surface wiring disposed on the upper surface of the substrate and a lower surface wiring disposed on the lower surface of the substrate. The upper surface wiring and the lower surface wiring are electrically connected through vias. The wiring can be formed of a metal such as copper, aluminum, gold, silver, tungsten, iron or nickel, or an alloy such as iron-nickel alloy or phosphor bronze.

  The light-emitting device according to the embodiment of the present invention is used in a wide range of applications such as various display devices, lighting fixtures, displays, backlight light sources of liquid crystal displays, and image reading devices and projector devices in facsimiles, copiers, scanners, and the like. Can be used.

DESCRIPTION OF SYMBOLS 100 ... Light-emitting device 10 ... Light emitting element 11 ... Laminated structure 111 ... 1st semiconductor layer 112 ... 2nd semiconductor layer 12 ... Electrode 121 ... 1st electrode 122 ... 2nd electrode 20 ... Substrate 21 ... Base material 22 ... Wiring 221 ... 1st wiring 222 ... 2nd wiring 23 ... Via 30, 30A ... Bump 31, 31A ... 1st bump 311, 311A ... Central 1st bump 312, 312A ... Outer periphery 1st bump 313, 313A ... Auxiliary 1st bump 32, 32A ... second bump 40 ... sealing member R ... element placement region R1 ... center portion of element placement region R2-R17 ... peripheral portion of element placement region Q1, Q2 ... region obtained by dividing element placement region in half C: Center of element placement area

Claims (4)

Preparing a light emitting device having an electrode on the lower surface;
Preparing a substrate with wiring on the top surface;
Forming a plurality of first bumps and second bumps having a thickness smaller than that of the first bumps on an element mounting region on the upper surface of the substrate on which the light emitting elements are mounted;
Placing a light emitting element on the first bump, and then deforming the first bump so that the second bump and the light emitting element are in contact with each other;
With
The first bump includes at least three central first bumps disposed at a central portion of the element mounting area and at least three outer peripheral positions disposed at positions substantially equal to the distance from the center of the element mounting area. 1 bump,
A method for manufacturing a light-emitting device.   The method of manufacturing a light emitting device according to claim 1, wherein the outer peripheral first bump is disposed at a position where the distance from the central first bump is substantially equal.   The method for manufacturing a light emitting device according to claim 1, wherein the second bump is deformed.   The method of manufacturing a light-emitting device according to claim 1, wherein the outer peripheral first bumps are arranged at equal intervals.

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