JP2006261513A - Porcelain enamel substrate for mounting light emitting element, light emitting element module, lighting device, display device, and traffic signal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate for mounting a light emitting element that can simultaneously satisfy high thermal conductivity, high mounting precision, and high productivity, a light emitting element module, a display device, a lighting device, and a traffic signal. <P>SOLUTION: The porcelain enamel substrate for mounting a light emitting element is composed by coating a core metal with a porcelain enamel layer, and has a plurality of through-holes for transferring/positioning or a protrusion/recess structure at least on one side of the outer edge part. The light emitting element module is composed by mounting a light emitting element to the porcelain enamel substrate for mounting a light emitting element. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a light emitting element mounting hollow substrate on which a light emitting element such as a light emitting diode (hereinafter referred to as LED) is mounted on a substrate, a light emitting element module in which the light emitting element is mounted on the substrate, and illumination using the light emitting element module The present invention relates to a device, a display device, and a traffic signal device.

  When a light emitting element such as an LED is used in a lighting device, a display device, a traffic signal, or the like, the light emission intensity of the light emitting element becomes an important issue. As a means for improving the light emission intensity of the light emitting element, it is conceivable to increase the electric power injected into the light emitting element. When the electric power injected into the light emitting element is increased, the light intensity of the light emitting element increases with the magnitude of the electric power, but at the same time, the amount of heat generated by the light emitting element increases, leading to a decrease in light emission efficiency. For this reason, in light emitting element modules that require high light emission intensity, it is common to use a substrate with good heat dissipation such as an aluminum laminated substrate or a ceramic substrate.

  In addition, when a light-emitting element is used in a lighting device or a display device, since a plurality of light-emitting elements are arranged vertically and horizontally at a constant interval on a substrate, position accuracy when mounting the light-emitting element on the substrate is an important issue. . In order to mount the light emitting element on the substrate, a device such as a die bonder that mounts the light emitting element on the substrate after applying a bonding material, or a wire bonder that connects the electrode pad on the element surface and the electric circuit on the substrate with a gold wire is used. In the die bonder, as shown in FIG. 4, the substrate 1 inserted in the conveyance path 3 is hooked by a mechanical arm 4 having pins 5 and claws, conveyed to a region where the light emitting element is mounted, positioned, and then the light emitting element. Is implemented. For this reason, the substrate 1 is generally provided with a pin 5 and a through-hole 2 for hooking a claw.

When the light emitting element is mounted by this method, the mounting accuracy is determined by the accuracy of conveyance and positioning of the substrate. Therefore, the dimensional accuracy when manufacturing the substrate greatly affects the mounting accuracy. Therefore, in a light emitting element module that requires high mounting accuracy, it is common to use a glass epoxy substrate with good workability (see, for example, Patent Document 1).
JP 2001-24238 A

  However, the glass epoxy substrate is excellent in processability, but has a feature of low thermal conductivity. If a large amount of power is injected into the light-emitting element in order to obtain high light emission intensity, the heat generated from the light-emitting element cannot be efficiently released to the substrate. There were problems such as shortening the lifetime of the element.

On the other hand, the ceramic substrate is excellent in thermal conductivity, but is easily broken by an impact from the outside, and it is difficult to machine a through-hole for conveyance / positioning on the substrate. In addition, there is a method in which a through hole is formed in advance before the ceramic is sintered. However, since the ceramic shrinks during sintering, sufficient dimensional accuracy cannot be obtained. Therefore, in order to mount the light emitting element on the ceramic substrate, it is necessary to fix the substrate to a tray having through holes for conveyance / positioning and to put the tray together with the mounting machine. In this case, since the work of fixing the substrate to the tray requires manpower and time, there is a problem that productivity is remarkably lowered.
In addition, the mounting method described above has a problem in that the mounting accuracy of the light emitting element depends on the fixing accuracy of the substrate with respect to the tray, so that high positional accuracy cannot be obtained and the variation varies from substrate to substrate. In order to solve this problem, there is also a method of mounting an element after confirming the electrode position to be mounted in advance by image recognition of the CCD camera before mounting the element. Since it takes time to scan the substrate and find the electrode position, there is a problem that productivity is lowered.

As described above, the light-emitting element mounting substrate that has been used so far cannot simultaneously satisfy the high thermal conductivity, high mounting accuracy, and high productivity required for the light-emitting element module with a single substrate. There was a problem.
The present invention has been made in view of the above circumstances, and provides a light-emitting element mounting substrate, a light-emitting element module, a display device, a lighting device, and a traffic signal that can simultaneously satisfy high thermal conductivity, high mounting accuracy, and high productivity. Objective.

  In order to achieve the above object, the present invention provides a light emitting device comprising a core metal covered with a hollow layer and having a plurality of through-holes or concavo-convex structures for conveyance and positioning on at least one side of an outer edge portion. An enamel substrate for mounting is provided.

  In the light emitting element mounting enamel substrate of the present invention, the light emitting element mounting portion preferably has a reflective cup.

  The present invention also provides a light emitting element module comprising a light emitting element mounted on the above-described light emitting element mounting hollow substrate according to the present invention.

  Moreover, this invention provides the illuminating device which has the light emitting element module which concerns on this invention mentioned above.

  The present invention also provides a display device having the above-described light emitting element module according to the present invention.

  The present invention also provides a traffic signal device having the above-described light emitting device module according to the present invention.

The light emitting element mounting enamel substrate of the present invention has a plurality of through-holes or concavo-convex structures for conveyance and positioning on at least one side of the outer edge portion, so that heat generated from the light emitting element is efficiently released to the substrate side. A temperature increase of the light emitting element can be suppressed, and a decrease in light emission efficiency can be effectively suppressed.
In addition, since the hollow substrate has a structure in which the core metal is covered with a thin hollow layer, it has sufficient dimensional accuracy even if the hollow layer is baked after forming a plurality of through-holes or concavo-convex structures for transport and positioning on the core metal. And the light emitting element can be mounted on the substrate with high speed and high accuracy.
Further, since the hollow substrate having sufficient dimensional accuracy can be obtained, the mounting time of the light emitting element can be minimized and the productivity can be improved.
As described above, the light-emitting element mounting enamel substrate of the present invention can simultaneously satisfy high thermal conductivity, high mounting accuracy, and high productivity.

  Since the light emitting element module of the present invention is formed by mounting the light emitting element on the above-described enamel substrate for light emitting element mounting, the substrate cost and the processing cost for modularization can be reduced, and high quality light emission is achieved. An element module can be provided.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a plan view showing a first embodiment of a light emitting element mounting enamel substrate (hereinafter referred to as a hollow substrate) and a light emitting element module according to the present invention. The light emitting element module 10 of this embodiment is configured by mounting a plurality of light emitting elements 14 on a hollow substrate 11 in which a plurality of through holes 12 for conveyance and positioning are provided in a row on one side of an outer edge portion. .

  Two surfaces of the substrate electrodes 13A and 13B are provided on one surface (light emitting device mounting surface) of the enamel substrate 11, and a plurality of light emitting devices 14 are bonded on the one substrate electrode 13B by die bonding, so that One (lower) electrode pad and the one substrate electrode 13B are electrically connected. Further, the other (upper) electrode pad of the light emitting element 14 and the other substrate electrode 13A are electrically connected via a gold wire 15 by wire bonding. Each light emitting element 14 is sealed with a sealing resin 16.

  Here, a method for manufacturing the enamel substrate 11 will be described. For the core metal of the substrate, a low carbon steel plate or the like is used and cut into a desired shape and thickness. At the same time, a shape necessary for transport / positioning of the enamel substrate 11 such as a through-hole 12 (or concavo-convex structure) for transport / positioning is formed by machining or pressing to produce a core metal.

  Next, the core metal is suspended in a liquid in which glass powder is dispersed in an appropriate dispersion medium, and an electrode is disposed at a position facing the core metal, so that the glass in the liquid is electrodeposited on the core metal. Next, the core metal after electrodeposition of the glass is fired, and the glass is baked onto the core metal to form a hollow layer. At this time, since the glass is electrodeposited on the periphery of the through hole 12 and baked, the inside of the through hole 12 is also insulated. Next, substrate electrodes 13A and 13B for supplying power to the light emitting element 14 by printing a silver paste at a desired position on the enamel layer are manufactured.

  Next, mounting of the light emitting element 14 on the enamel substrate 11 will be described. First, a plurality of light emitting elements 14 are fixed at predetermined positions on the enamel substrate 11 using a die bonder device. At this time, a bonding material such as solder or silver paste is used for bonding the light emitting element 14 and the substrate electrode 13B on the surface of the enamel substrate 11. Next, the other electrode pad on the surface of the light emitting element 11 and the other substrate electrode 13A are connected by a gold wire 15 using a wire bonder to establish an electrical connection.

  The present invention is characterized in that a hollow substrate 11 is used as a substrate for a light emitting element module. The enamel substrate 11 is composed of a core metal and an enamel layer covering the surface thereof, and has excellent thermal conductivity. For this reason, similarly to the ceramic substrate, heat generated in the light emitting element 14 can be efficiently radiated to the substrate side, and a decrease in the light emission efficiency of the light emitting element 11 can be effectively suppressed.

  The second feature of the present invention is that a through-hole 12 for conveyance / positioning is formed on the hollow substrate 11. The low carbon steel plate used as the core metal of the enamel substrate 11 has high mechanical strength and high processing accuracy. Therefore, the hollow substrate 11 has a small warp even if it is increased in size, and the through-holes 12 for conveyance / positioning can be easily formed with high accuracy by machining or pressing. Therefore, since the enamel substrate 11 can be directly conveyed and positioned accurately on the mounting machine without using a tray or the like, the mounting position input to the mounting machine in advance can be obtained without using an image recognition system using a CCD camera. With only information, the light-emitting element 14 can be mounted at a predetermined position on the substrate with high speed of light and high accuracy, and productivity can be improved.

  As described above, when the enamel substrate 11 having the through holes 12 for conveyance / positioning is used as the mounting substrate for the light emitting element module 10, high thermal conductivity and high mounting accuracy required for the light emitting element module 10 are used. And high productivity can be simultaneously satisfied with one substrate.

  The enamel substrate 11 has high mechanical rigidity, and has a feature that the through-hole 12 can be used not only for conveying / positioning but also as a screw hole for fixing a module.

  FIG. 2 is a cross-sectional view showing a second embodiment of the enamel substrate and the light emitting element module according to the present invention. The light emitting element module 20 of the present embodiment is configured to include substantially the same components as the light emitting element module 10 according to the first embodiment described above, and further the light emitting element of the enamel substrate 21 in which the core metal 22 is covered with the enamel layer 23. A reflection cup shape is formed by recessing the periphery of the mounting position, the light emitting element 14 is mounted at the center, and the light emitting element 14 is sealed by filling the reflection cup with a sealing resin 16.

  In order to take out the light emitted from the light emitting element 14 to the front surface of the substrate, it is common in the mounting structure of the light emitting element to form a reflective cup shape on the substrate. In the case of the enamel substrate of the present invention, a reflective cup as shown in FIG. 2 can be formed on the enamel substrate 21. Also in this case, the core metal 22 in which a cup shape is formed in advance by a method such as press working on a low carbon steel plate is used, the enamel layer 23 is electrodeposited and baked, and a silver paste is applied also in the cup to form a substrate. By forming the electrodes 13A and 13B, the light emitted from the light emitting element 14 can be efficiently extracted in front of the substrate.

  FIG. 3 is a cross-sectional view showing a third embodiment of the enamel substrate and the light emitting element module according to the present invention. The light emitting element module 30 of the present embodiment uses a hollow substrate 31 provided with concave and convex portions 32 on both sides instead of the through holes, and is otherwise substantially the same as the light emitting element module 10 according to the first embodiment described above. It is configured with components.

  In the present embodiment, the same effects as those of the enamel substrate and the light emitting element module of the first embodiment described above can be obtained. Further, the concavo-convex portion 32 can be used not only for conveyance / positioning but also for positioning for fitting the substrates together when a plurality of substrates are aligned and joined together. Further, the uneven portion 32 may be sandwiched between sockets and used as an electrode for supplying power from the outside.

  The light emitting element used in the light emitting element module of the present invention is not particularly limited. For example, a blue light emitting element or a green light emitting element typified by a gallium nitride compound semiconductor may be used, or a red light emitting element typified by GaP. An element may be sufficient. In addition to the LED, a semiconductor laser diode (LD), an organic EL element, or the like can also be used. Further, a white LED module can be configured by mounting a blue LED on a hollow substrate and mixing a blue excited yellow light emitting phosphor in a sealing resin.

The light emitting element module of the present invention can be applied to a lighting device by constituting a white LED module as described above.
In addition, a display device can be configured by appropriately arranging a blue light emitting element, a green light emitting element, and a red light emitting element on an enamel substrate.
Similarly, a traffic light can be configured by concentrating blue light emitting elements, yellow light emitting elements, or red light emitting elements on a hollow substrate.

<Production of enamel substrate>
A 1.5mm-thick low-carbon steel plate is cut into a size of 50mm x 100mm, and machining is performed with a drill so that through-holes with an inner diameter of 2mm for conveying and positioning the substrate are placed at a distance of 10mm at a position 5mm from the edge of the steel plate. Was used to make a core metal.
Next, the core metal was suspended in a liquid in which glass powder was dispersed in a dispersion medium. Further, an electrode was disposed at a position facing the core metal, and glass was electrodeposited on the core metal. Next, the core substrate after electrodeposition of the glass was baked, and the glass was baked onto the core metal to produce a hollow substrate. The inner diameter of the through hole of the obtained enamel substrate was 1.5 mm in diameter, and the thickness of the enamel layer on the substrate surface was 200 μm.
On this enamel layer, an electrode / electric circuit was produced by a silver paste using a screen printing method and baked.

<Mounting of light emitting element>
A light emitting element emitting blue light (gallium nitride compound semiconductor blue LED) was mounted on the enamel substrate. First, a die bonder was used, and the electrode adjacent to the electrode pad on the surface of the light emitting element was electrically connected with a gold wire having an outer diameter of 25 μm. Furthermore, the light emitting element was sealed with an epoxy resin to obtain a light emitting element module.

  For comparison, a ceramic substrate (without through-holes) having the same shape as the enamel substrate was prepared, and electrodes / electric circuits were prepared by using a silver paste using a screen printing method and baked. After mounting the same light emitting element on the ceramic substrate with the same die bonder, the positional accuracy was compared.

  At this time, the number of substrates was 5 for both substrates, and the number of mounted light emitting elements was 10 / substrate. A silver paste was used as the bonding material. As a result, the light-emitting element could be mounted with an accuracy of ± 5 μm on the enamel substrate, whereas the ceramic substrate was mounted with an accuracy of ± 30 μm. At this time, the time required to fix the ceramic substrate to the transfer tray was 30 seconds / substrate for one worker.

It is a top view which shows 1st Embodiment of the light emitting element module of this invention. It is sectional drawing which shows 2nd Embodiment of the light emitting element module of this invention. It is a top view which shows 3rd Embodiment of the light emitting element module of this invention. It is a perspective view for demonstrating the conveyance form of a board | substrate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 20, 30 ... Light emitting element module, 11, 21, 31 ... Hollow substrate (hollow board | substrate for light emitting element mounting), 12 ... Through-hole, 13A, 13B ... Substrate electrode, 14 ... Light emitting element, 15 ... Gold wire, 16 ... sealing resin, 22 ... core metal, 23 ... enamel layer, 32 ... uneven part.

Claims (6)

  A hollow substrate for mounting a light-emitting element, wherein a core metal is covered with a hollow layer, and has a plurality of through-holes or a concavo-convex structure for conveyance and positioning on at least one side of an outer edge portion.   The light emitting element mounting enamel substrate according to claim 1, wherein the light emitting element mounting portion has a reflective cup.   A light emitting element module comprising a light emitting element mounted on the light emitting element mounting enamel substrate according to claim 1.   The illuminating device which has a light emitting element module of Claim 3.   A display device comprising the light emitting element module according to claim 3. A traffic signal having the light emitting element module according to claim 3.

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