JP2019110204A - Semiconductor light emitting device, general purpose mounting substrate, and method of manufacturing semiconductor light emitting device using the same - Google Patents

Abstract

To provide a general-purpose mounting substrate that can correspond to LED chips of different sizes and has no problem of LED chip misalignment or excessive bonding material spreading.SOLUTION: The general-purpose mounting substrate is provided with a mounting pad 13 formed for joining any of a plurality of semiconductor light emitting elements having different sizes. The mounting pad 13 has a first area 131 and a second area 132 located inside the first area 131. A step is formed between the first area 131 and the second area 132. Since the area is determined by the step, a displacement of an LED chip is prevented. Furthermore, an excess bonding material does not spread to a substrate side.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a semiconductor light emitting device in which a semiconductor light emitting element such as a light emitting diode (LED) is mounted on a device mounting substrate (hereinafter referred to as a mounting substrate) and a method of manufacturing the same.

  As a semiconductor light emitting device, a semiconductor light emitting element (hereinafter also referred to as an LED chip) is bonded to a pad for mounting an element (mounting pad) made of a metal film formed on the surface of an insulating substrate with a bonding material. A light emitting device packaged by resin molding after wire bonding is widely used. In this type of light emitting device, in order to effectively diffuse the heat generated by the LED chip to the substrate side, it is preferable that the LED chip be bonded to the mounting pad on the entire surface by a bonding material. If a large amount of bonding material is supplied during the process, the melted bonding material may spread around or wrap around the LED chip during reflow. In order to solve this problem, for example, it is proposed to provide a protrusion on the outside of the portion of the mounting pad to which the LED chip is bonded (Patent Document 1) or to provide a groove (Patent Document 2).

JP, 2009-76524, A JP 2012-109352 A

  Some LED chips have different sizes, such as 1 mm square, 0.7 mm square, 0.5 mm square, etc. In the above-mentioned prior art, the projections and grooves provided on the mounting pad depend on the size of the LED chip. In order to determine it, it is necessary to prepare a mounting substrate for each of the LED chips of different sizes. On the other hand, although it is possible to cope with LED chips of any size by using a mounting substrate provided with a mounting pad having a large area corresponding to the largest LED chip, a small LED can be used for such a large mounting pad When the chips are joined, the LED chip may be displaced or rotated from a position to be originally fixed by fluidizing the molten bonding material at the time of reflow. When the bonding material solidifies in that state, the LED chips are bonded with their positions shifted. When such a light emitting device is applied to a light source such as illumination, there is a problem that the optical design becomes difficult because the position of the light source is shifted.

  The present invention provides a general-purpose mounting substrate that can be used for LED chips of different sizes without the problem of misalignment of the LED chips and the spread of extra bonding material, and the LED chips on such mounting substrates. An object is to provide a mounted semiconductor light emitting device.

  In order to solve the above problems, in the semiconductor light emitting device of the present invention, the mounting pad of the mounting substrate has a plurality of mounting areas corresponding to the sizes of the plurality of LED chips. The plurality of mounting areas have different thicknesses, and a step is formed at the boundary between adjacent areas.

  That is, the semiconductor light emitting device of the present invention includes a mounting substrate having a mounting pad made of a metal film, and a semiconductor light emitting element joined to the mounting pad via a bonding material, and the mounting pad is a first region And a second region located inside the first region, and has a step in the thickness direction of the mounting pad at the boundary between the first region and the second region.

  The semiconductor light emitting device is any of a plurality of light emitting devices having different sizes, and the outer periphery of the second region is smaller in size than the outer periphery of the largest light emitting device of the plurality of light emitting devices and the second largest light emission The same size as or larger than the outer circumference of the element.

  According to the present invention, since the plurality of mounting areas are separated by the step, for example, when mounting an LED chip smaller than the outer periphery of the mounting pad, the LED is melted even when the bonding material melts and flows Since the movement range of the chip is limited to the inside divided by the step, there is no problem of misalignment. Further, by supplying the bonding material only to the area where the small LED chip is placed, it is possible to prevent the bonding material from spreading outside the mounting pad. When mounting an LED chip as large as the outer periphery of the mounting pad, the LED chip is positioned along the outer periphery of the mounting pad by the force (surface tension) of the melted bonding material remaining on the surface of the mounting pad There is no misalignment.

FIG. 1 is a side cross sectional view showing an embodiment of a semiconductor light emitting device. It is a figure which shows the versatile mounting board of 1st embodiment, (A) is the figure seen from the upper surface, (B) is the sectional view on the AA line of (A). FIG. 7 is a process diagram illustrating a method of manufacturing the semiconductor light emitting device of the first embodiment. (A)-(C) are figures which show the procedure which mounts a small chip to the general purpose mounting substrate of 1st embodiment. (A)-(C) are the figures which show the procedure which mounts a large chip to the general purpose mounting board of 1st embodiment. It is a figure which shows the modification 1 of the general purpose mounting board of 1st embodiment, (A) is sectional drawing of a mounting pad part, (B) is a figure which shows the mounting state of the small chip to a mounting pad, (C) is mounting. The figure which shows the mounting state of the large chip to a pad. It is a figure which shows the modification 2 of the general purpose mounting board of 1st embodiment, (A) is the figure seen from the upper surface, (B) is a BB sectional view taken on the line of (A). It is a figure which shows an example of the general purpose mounting board of 2nd embodiment, (A) is the figure seen from the upper surface, (B) is the CC sectional view taken on the line of (A). It is a figure which shows another example of the general purpose mounting board of 2nd embodiment, (A) is the figure seen from the upper surface, (B) is the DD sectional view taken on the line of (A).

Hereinafter, embodiments of the semiconductor light emitting device of the present invention will be described.
FIG. 1 shows an embodiment of a semiconductor light emitting device of the present invention. The semiconductor light emitting device includes a mounting substrate 10 and an LED chip 30 bonded to the mounting substrate 10 by a bonding material 20. Furthermore, the LED chip 30 is usually sealed with a sealing resin such as a translucent resin or a phosphor-containing resin. In the case of sealing with the sealing resin 50, a cylindrical wall member 60 for injecting the uncured sealing resin 50, a reflecting member having an inverted frusto-conical shape on the inner surface, and the like are arranged along the outer periphery of the mounting substrate 10. can do.

  The mounting substrate 10 is made of an insulating substrate such as a glass epoxy substrate or a ceramic multilayer substrate, and a conductor wiring 11 made of a metal such as Au or Cu for feeding power to the LED chip 30 is formed. A mounting pad 13 for bonding the LED chip 30 is formed in the portion. The mounting pad 13 has a shape capable of mounting an LED chip of any size among a plurality of LED chips of a plurality of sizes, not the LED chip 30 of a specific size. The specific shape of the mounting pad will be described later. The conductor wiring 11 and the mounting pad 13 may be a multilayer film made of different metals in addition to a single layer film of metal. Depending on the structure, the conductor wiring 11 and the mounting pad 13 may be formed by any method such as photolithography, sputtering, or evaporation. It can be formed on an insulating substrate.

  The bonding material 20 bonds the mounting pad 13 which is a metal and the electrode surface of the LED chip 30, and is a metal material which melts at a relatively low melting point, such as SnPb, SnAgCu, AuSn, SnZn, ZnCu Alloys such as can be used. Such a metal material has excellent wettability to the mounting pad 13 made of metal in melting (melting point) and low wettability to the insulating substrate, and therefore when dropped onto the mounting pad 13, the outer edge of the mounting pad 13 , Without spreading on the insulating substrate which is the outside, it stays on the mounting pad 13 and suppresses the movement of the LED chip 30 placed thereon.

  The LED chip 30 has a structure in which a p-type semiconductor and an n-type semiconductor are joined, and includes a single-sided type in which both electrodes are formed on one side and a double-sided type in which electrodes are formed on the front and back sides. In this embodiment, although any type can be adopted, in the case of a single-sided type in which both electrodes are formed on the upper surface, it is preferable to form a metal film on the back surface side. FIG. 1 shows an example using a double-sided type in which an n electrode is disposed on the back surface side and a p electrode is disposed at the center on the top surface side, and the back surface on which the n electrode is formed The p electrode is bonded to the conductor wiring 11 (electrode pad) of the mounting substrate 10 by wire 40 such as Ag. The semiconductor is not limited, but, for example, compound semiconductors such as GaAs, GaP, AlGaInP, InGaN and the like are used. The electrode is formed of a single layer film or a laminated film of Al, Ag, Au, Pd or the like.

  The shape of the LED chip 30 is not particularly limited, but generally the one having a square shape as viewed from the top is often used, and they can be used. The size of the LED chip 30 is, for example, 1 mm square, 0.7 mm square, or 0.5 mm square as a size of a square viewed from the top. The semiconductor light-emitting device of this embodiment uses a mounting substrate corresponding to a plurality of sizes of LED chips as a mounting substrate, and any LED chip among a plurality of sizes of LED chips is not limited to a specific size. Can be used.

  Next, an embodiment of the mounting substrate 10 used for the above-described semiconductor light emitting device will be described. Here, a specific example of a mounting substrate having mounting pads corresponding to two LED chips having different sizes, the large chip 30L and the small chip 30S, will be described as an example.

First Embodiment
FIG. 2 shows the mounting pad portion of the mounting substrate 10 of the first embodiment. In the figure, (A) is a top view of the mounting pad 13, (B) is a cross-sectional view taken along the line A-A of (A). As illustrated, the mounting pad 13 of the present embodiment has a shape as viewed from the upper surface that is similar to the shape of the LED to be mounted (a square in the illustrated example) and has a predetermined thickness from the substrate surface A first region 131 having a thickness t1 and a second region 132 which is inside the first region 131 and has a thickness different from that of the first region 131 are formed. That is, the step 13D of thickness is formed between the first area 131 and the second area 132. In the present embodiment, the thickness t2 of the second region 132 is smaller than the thickness t1 of the first region, and thus the second region is formed as a recess.

The outer periphery of the second region 132 is smaller than the outer periphery of the large chip 30L and equal to or smaller than the outer periphery of the small chip 30S. For example, in the width in the vertical direction shown in FIG. 2, assuming that the width of the large chip is w _30L and the width of the small chip is w _30S , the width W1 of the first region and the width W2 of the second region are
W1 ≧ w _30L > W2 ≧ w _30S
It is preferable that For example, W1 is selected to be √2 times or twice as wide as W2. The same applies to the width in the lateral direction.

  The mounting substrate 10 having such a mounting pad is formed by, for example, forming a metal film on the insulating substrate by a method such as printing, photolithography, vapor deposition, etc. to form the conductor wiring 11 and the mounting pad 13. The metal film of the entire area of the mounting pad 13 is formed to have the thickness t2 of the area of the above, and then the metal film of a further thickness (t1-t2) is formed around the second area masked. The metal film of the entire area of the mounting pad 13 may be formed to have a thickness t1 of the first region, and then the second region is etched to form a recess having a depth (t1-t2). You may

  Next, a method of manufacturing a semiconductor light emitting device using the mounting substrate of the present embodiment will be described with reference to FIGS.

  First, a mounting substrate on which the mounting pad 13 having the predetermined conductor wiring 11 and the recess (second region) 132 described above is formed is prepared as the mounting substrate 10 (S301). A predetermined amount of bonding material is supplied to the recess 132 in accordance with the size of the LED chip to be mounted (S302). In this state, the bonding material 20 is in the form of a paste containing a binder, a flux agent, and the like in addition to a metal material such as AuSn, and can be supplied by coating or potting. In the case of the small chip 30S, as shown in FIG. 4A, the amount of the bonding material to be supplied can cover the bottom of the recess 132 and be slightly smaller than the volume of the recess 132. In the case of the large chip 30L, as shown in FIG. 5A, after being filled in the recess 132, the first region 131 can be further covered. The amount of such a bonding material can be empirically known from the size of the recess 132 and the size of the LED chip, and thus these empirical values are appropriately supplied.

  In the case of the large chip 30L, the bonding material may be supplied not only to the recess 132 but also to the periphery (first region) 131 of the recess 132 as necessary. However, the bonding material supplied to the first area is divided into a plurality of parts and supplied so that there is no air layer between the bonding material supplied to the recess 132 and the bonding material supplied to the first area, It is preferable to secure a way for air to escape.

  Then, the LED chip 30 is disposed on the mounting pad 13 (S303). In the case of the small chip 30S, the LED chip is placed in the recess 132 (FIG. 4B), and in the case of the large chip 30L, along the outer contour of the first region 131 (FIG. 5B). Press down. In a state where the LED chip 30 is temporarily fixed on the mounting substrate by the bonding material 20, the mounting substrate 10 is placed in a reflow furnace and heated for a predetermined time, and then the bonding material 20 is cured to bond the LED chip 30 (S304). The paste-like bonding material 20 is melted by heating at the time of reflow and has fluidity, but since the small chip 30S is disposed in the concave portion 132 of the mounting pad 13, it is possible to prevent positional deviation, As the bonding material 20 cures, it is fixed and bonded onto the second region 132 (FIG. 4C, FIG. 5C).

  Thereafter, wire bonding an electrode (not shown) provided on the upper side of the LED chip to the electrode pad of the mounting substrate 10 (S305), and if necessary, seal the LED chip after wire bonding with a translucent resin Stopping (S306) is similar to the manufacture of a conventional semiconductor light emitting device.

  According to the present embodiment, by making the area of the mounting substrate on which the small chip is mounted a concave, movement of the small chip occurs even if the bonding material melts and takes on fluidity when the small chip is mounted with the bonding material. Is limited by the level difference, so there is no misalignment. Further, even if the bonding material extends from the second region which is the recess, it remains in the first region and the bonding material does not extend to the wire bonding portion. In the case of mounting a large chip, it is similar to a conventional mounting substrate having a mounting pad without a recess corresponding to the size of the chip, and the bonding material for the large chip is used by using an appropriate amount of bonding material. It is possible to maintain the arrangement state in which the four sides of the mounting pad and the four sides of the chip are aligned. Further, due to the difference in the wettability to the bonding material between the metal forming the mounting mud and the insulating substrate, the bonding material is prevented from spreading outward.

  Then, by using this mounting substrate, all the chips of any size do not have displacement of the LED chip, and the entire back surface is bonded to the mounting pad through the bonding material, so that the heat generated by the LED chip is dissipated A semiconductor light emitting device having an easy structure is provided.

  In the embodiment described above, the case of using a double-sided type in which one electrode is provided on the back surface and the other electrode is provided on the top surface as the LED chip has been described. The same applies.

  Moreover, although the case where a single LED chip was mounted on an insulating substrate was demonstrated in the above embodiment, the number of LED chips to mount may be multiple. In that case, a mounting substrate in which a plurality of mounting pads are formed on the insulating substrate is prepared. The present embodiment also includes the case where at least one mounting pad among the plurality of mounting pads is the above-described general-purpose mounting pad.

<Modified Example 1 of First Embodiment>
In the mounting substrate of the first embodiment, the second region of the mounting pad corresponding to the small chip is a concave portion having a small thickness, but the second region is a convex portion having a thickness larger than that of the first region. It is also good.

  FIGS. 6A to 6C show the mounting pad 130 of the mounting substrate of this modification and the state in which the small chip 30S and the large chip 30L are bonded to the mounting pad 130 with a bonding material. Similarly to the first embodiment, the mounting pad of this modification is formed by dividing the film formation into two steps or by combining the film formation and the etching to form a mounting pad having a step 13D between the regions. Can.

  The method of manufacturing a semiconductor light emitting device using the mounting substrate of this modification is the same as that of the first embodiment in the procedure of FIG. 3 but in the case of bonding large chips (S 302 in FIG. 3), bonding The material may be supplied not only to the second region 132 which is a convex portion but also to the first region 131, for example, along four sides or at a plurality of places at four corners. As a result, the bonding material 20 can be spread over the entire first region 131 having a smaller step than the second region 132, and the entire back surface of the large chip can be bonded to the mounting pad via the bonding material. It is possible to obtain a semiconductor light emitting device with good pulling.

  Also in this modification, when bonding the small chip, by arranging in the second region corresponding to the size, when the bonding material is melted, the movement of the small chip exists due to the surface tension of the bonding material. Since the second region is limited, positional deviation can be prevented, and the same effect as that of the first embodiment can be obtained.

<Modified Example 2 of First Embodiment>
In the first embodiment, the mounting substrate for mounting two types of LED chips having different sizes of the small chip and the large chip has been described, but by providing a plurality of steps, it is possible to cope with three or more types of LED chips. Is also possible.

An example of the mounting pad 1300 of the mounting board corresponding to 3 or more types of LED chips is shown in FIG. In the illustrated example, the first area 131, the thinner second area 132, and the thinner third area 133 are formed sequentially from the outside of the mounting pad 1300. That is, a recess is formed inside the first region 131, and a recess is further formed inside the recess. The widths (widths in any direction) W1, W2, and W3 of the first to third regions respectively indicate the widths of three types of LED chips having different sizes, the large chip, the middle chip, and the small chip in the same direction. , _W30L , _w30M , _w30S ( _w30L > _w30M > _w30S ), the following relationship is preferable.
W1 ≧ w _30L > W2 ≧ w _30M > W3 _{ww 30S}

  Also in this modification, the middle chip and the small chip can be joined on the mounting substrate without misalignment, respectively, by the recess that defines the second region 132 and the recess that defines the third region 133.

  In the present modification, the second area and the third area are recessed in a nested manner with respect to the first area, but the second area and the third area are sequentially formed to be thick projections It is also possible to use one of them as a recess and the other as a protrusion, and the same effect can be obtained.

Second Embodiment
In the first embodiment and its modification, the plurality of regions provided on the mounting pad are divided by the step, but as means for dividing the region, means other than the step may be added. Hereinafter, the present embodiment will be described by exemplifying mounting boards corresponding to three types of LED chips, large chips, middle chips, and small chips having different sizes.

  The mounting pads shown in FIGS. 8 and 9 are mounting pads in which slits or grooves are formed in addition to the steps. In the mounting pad 130A shown in FIG. 8, a second region 132 corresponding to the middle chip is formed with a step inside the first region 131 located on the outermost side of the size corresponding to the large chip. Inside the four sides forming the outer periphery of the second region 132, slits 137 are formed in parallel with the four sides. The area surrounded by the four slits 137 is a third area 133 corresponding to the small chip.

  Further, in the mounting pad 130B shown in FIG. 9, the third region 133 corresponding to the small chip is formed with a step inside the first region 131, and four L-shapes are formed inside the first region 131. The groove 138 is formed, and the area (except the third area) surrounded by the four grooves 138 is a second area 132 corresponding to the middle chip. Instead of the grooves 138, slits may be used.

  In both figures, the relationship between the width of each area and the width of each LED chip is the same as that of the second modification of the first embodiment. Although FIG. 8 illustrates linear slits and FIG. 9 illustrates L-shaped grooves, the shapes of the slits or grooves may be reversed in FIGS. 8 and 9, or may be appropriately combined. Slits and grooves may be interchanged. The linear slit may be a slit obtained by dividing one into a plurality.

  Also in the present embodiment, it is the same as that of the first embodiment in that the steps separating the regions prevent the positional deviation of the LED chips disposed on the inner side. On the other hand, the slits or grooves are made of a bonding material utilizing the difference in wettability to the bonding material between the material of the mounting pad (metal film) and the material of the substrate surface (glass epoxy, ceramic etc.) on which the mounting pad is formed. By restricting the movement range within the mounting pad, the movement of the LED chip is limited. Thus, for example, even if the bonding material is melted and fluidized, the LED chip disposed in the area surrounded by the slits 137 stays with the bonding material in that area, and the bonding material is cured and the mounting pad is not displaced. Bonded on top.

  As described above, according to the present embodiment, by using the step and the slit or the groove in combination, a mounting substrate that can correspond to any of three or more types of LED chips having different sizes is provided, and the mounting substrate is used. Thus, regardless of the size of the LED chip mounted, it is possible to obtain a semiconductor light emitting device which is free from positional deviation and in which the excessive spread of the bonding material is suppressed.

  The embodiments of the semiconductor light emitting device of the present invention and the mounting substrate used therefor have been described above, but the drawings used for the description of each embodiment are merely an example, and the structure of the semiconductor light emitting device, the type and shape of the LED chip, etc. The present invention can be applied to known structures and types without being limited to these drawings.

10: mounting substrate, 11: conductor wiring, 13: mounting pad, 20: bonding material, 30: LED chip (semiconductor light emitting element), 30L: large chip, 30S: small chip, 31: electrode (metal film), 40: Wire rod 50: sealing resin 60: wall material 130: mounting pad 130A: mounting pad 130B: mounting pad 131: first area 132: second area 133: third area 137 : Slit, 138: Groove, 1300: Mounting pad

Claims (10)

A mounting substrate having a mounting pad made of a metal film, and a semiconductor light emitting device joined to the mounting pad via a bonding material.
The mounting pad has a first region and a second region located inside the first region, and at the boundary between the first region and the second region, the mounting pad What is claimed is: 1. A semiconductor light emitting device having a step in the thickness direction of the semiconductor device. The semiconductor light emitting device according to claim 1, wherein
The semiconductor light emitting device is any of a plurality of light emitting devices of different sizes, and the outer periphery of the second region is smaller than the periphery of the largest light emitting device of the plurality of light emitting devices and is the second largest light emission A semiconductor light emitting device having the same size as or larger than the outer circumference of the device. A semiconductor light emitting device according to claim 1 or 2, wherein
The semiconductor light-emitting device according to claim 1, wherein a film thickness of the second area of the mounting pad is larger than a film thickness of the first area. A semiconductor light emitting device according to claim 1 or 2, wherein
The semiconductor light emitting device according to claim 1, wherein a film thickness of the second region of the mounting pad is smaller than a film thickness of the first region. A semiconductor light emitting device according to claim 1 or 2, wherein
The semiconductor light emitting device according to claim 1, wherein the mounting pad has a slit portion or a groove portion in which the metal film is not formed between an outer periphery of the first region and a boundary between the second region. The semiconductor light emitting device according to claim 1, wherein
The bonding material is provided inside the second region,
The semiconductor light emitting device, wherein the semiconductor light emitting element is equal to or smaller than an outer periphery of the second region. The semiconductor light emitting device according to claim 1, wherein
The bonding material is provided to extend to the first area and the second area,
The semiconductor light emitting device, wherein the semiconductor light emitting element is larger than an outer periphery of the second region and equal to or smaller than an outer periphery of the first region. A general-purpose mounting substrate having a mounting pad formed of a metal film for bonding any of a plurality of semiconductor light emitting elements having different sizes,
The mounting pad has a first region and a second region located inside the first region, and at the boundary between the first region and the second region, the mounting pad Have a step in the thickness direction of the
The outer periphery of the second region is the same size as or larger than the outer periphery of the second largest light emitting element smaller than the outer periphery of the largest light emitting element among the plurality of light emitting elements. Mounting board. A semiconductor light emitting device is manufactured by bonding a semiconductor light emitting element to a mounting material of a mounting substrate having a mounting pad formed on the surface, using a bonding material.
Preparing the general-purpose mounting board according to claim 8 as the mounting board;
Supplying the bonding material only to the second region of the mounting pad, and placing a semiconductor light emitting element whose outer periphery is the same as or smaller than the outer periphery of the second region on the mounting pad;
Bonding the semiconductor light emitting element and the mounting pad with a bonding material. A semiconductor light emitting device is manufactured by bonding a semiconductor light emitting element to a mounting material of a mounting substrate having a mounting pad formed on the surface, using a bonding material.
Preparing the general-purpose mounting board according to claim 8 as the mounting board;
The mounting pad is supplied with the bonding material to the second region of the mounting pad, and the semiconductor light emitting element whose outer periphery is smaller than or equal to the outer periphery of the first region and larger than the outer periphery of the second region Steps to put on
Bonding the semiconductor light emitting element and the mounting pad with a bonding material.

Images