JP3778597B2 - LED chip die bonding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow high density die bonding with a plurality of LED chips cross to each other by die bonding the thinnest LED chip first out of a plurality of LED chips of different thickness. SOLUTION: To a base body 11, LED chips of different thickness are, through a bonding agent 13, die bonded in the order of thickness wherein the thinnest one first. In short, the thinner LED chip T1 is die bonded first, then the thicker LED chip T2 is die bonded. So, even if the thicker LED chip T2 is die bonded cross to the LED chip T1 die bonded already, since there exists height difference of Δh between the LED chips T1 and T2, the LED chip T1 is never touched with a die-bonder collet 12. Therefore, a plurality of LED chips are die bonded in high density. Further, since LED chips are die bonded cross to each other, mixture color of light emission is improved, and so, color variation and fluctuation in light emission characteristics are prevented.

Description

[0001]
[Industrial application fields]
[0002]
The present invention relates to a method for die bonding a plurality of LED chips to a substrate.
[Prior art]
[0003]
Usually, an LED chip is die-bonded to a substrate such as a lead frame or a package, and then electrically connected to a pair of lead electrodes formed on the substrate to form an LED. In order to die-bond the LED chip to the substrate, an automatic device called a die bonder is usually used. The die bonder collet provided in the die bonder sucks and conveys the LED chips one by one and die-bonds to a predetermined position on the substrate.
[0004]
In general, in order to obtain a desired light distribution characteristic, an LED chip as a light source is made as close to a point light source as possible, and light emitted from the LED chip is collected to a desired light distribution characteristic by a lens and a reflecting mirror. A light or diffused method is employed. In particular, an LED including a plurality of LED chips needs to be die-bonded at a high density by bringing the plurality of LED chips as close as possible.
[Problems to be solved by the invention]
[0005]
However, conventionally, when a plurality of LED chips are die-bonded, the thickness of the plurality of LED chips die-bonded to the substrate is almost the same. Therefore, the LED chip is die-bonded so as to be close to the previously die-bonded LED chip. If it is going to do, since the die bonder collet which adsorb | sucks and conveys this LED chip will contact the LED chip | tip previously die-bonded, the problem of the damage | wound of the LED chip | tip previously die-bonded and position shift will generate | occur | produce. For this reason, in the conventional method, it is impossible to die-bond a plurality of LED chips close to each other at a high density, so that the light source becomes discrete and it is difficult to realize a desired light distribution characteristic. It was.
[0006]
Accordingly, the present invention has been made to solve the above-described drawbacks, and an object of the present invention is to provide a method of die bonding at a high density by bringing a plurality of LED chips close to each other.
[Means for Solving the Problems]
[0007]
The LED chip die-bonding method of the present invention is a die-bonding method in which a plurality of LED chips are die-bonded to a substrate, wherein the plurality of LED chips are LED chips having different thicknesses, and the first die-bonded LED chip and the later die-bonded. The distance between the LED chip and the LED chip is closer to the distance between the end of the die bond collet that sucks and conveys the LED chip to be die-bonded later and the LED chip to be die-bonded later, and a thin LED chip is used. The LED chip die-bonding method is characterized in that die bonding is performed before the thick LED chip die-bonded between the thin LED chips.
[0008]
In the present invention, the plurality of LED chips further include two or more types of LED chips having different emission colors. Any LED chip may be used as long as the LED chip has a different emission color, but three types of red, green, and blue LED chips necessary for full color emission are particularly preferably used.
[Action]
[0009]
FIG. 7 is a schematic cross-sectional view for explaining a conventional die bonding method. The LED chip is die-bonded to a substrate 31 with an adhesive 33 using a die bonder collet 32. As shown in the figure, in the conventional die-bonding method, adjacent LED chips have the same thickness. Therefore, when an LED chip is to be die-bonded close to the previously die-bonded LED chip, a die bonder collet 32 that sucks and conveys the LED chip. However, since it comes into contact with the previously die-bonded LED chip, the previously die-bonded LED chip is damaged and misaligned. Therefore, conventionally, in order to avoid contact between the LED chip previously die-bonded and the die bonder collet 32, it is necessary to die-bond with an appropriate distance between the LED chips.
[0010]
FIG. 1 is a schematic cross-sectional view for explaining the die bonding method of the present invention. LED chips having different thicknesses are bonded to a substrate 11 via an adhesive 13. In the present invention, die bonding is performed in order from the thin LED chip. That is, the thinner LED chip T1 is die-bonded first, and then the thicker LED chip T2 is die-bonded. Then, even if the thicker LED chip T2 is die-bonded close to the previously die-bonded LED chip T1, as shown in FIG. 1, there is a difference of Δh in the surface height between the LED chips T1 and T2. The die bonder collet 12 does not come into contact with the LED chip T1. Therefore, it becomes possible to die-bond a plurality of LED chips with high density.
[0011]
In addition, in a multicolor light emitting device provided with LED chips having different emission colors, if LED chips are discretely die-bonded as in the conventional case, color mixing failure of light emission from each LED chip occurs, and color unevenness or This causes fluctuations in the light emission characteristics. In the present invention, since a plurality of LED chips having different emission colors can be die-bonded close to each other, color mixture of light emission from each light-emitting chip is improved, and color unevenness and variation in light emission characteristics can be prevented.
【Example】
[0012]
The LED chip die-bonding method of the present invention will be described in detail based on examples.
[Example 1]
FIG. 2 is a schematic cross-sectional view showing the form of an LED chip die-bonded by the method of the present invention. In this embodiment, LED chips having two kinds of thickness are die-bonded on the same substrate using a die bonder collet. First, of the two types of LED chips, the thinner LED chip T1 is die-bonded on the substrate 11 first. Next, the thicker LED chip T2 is die-bonded between the thinner LED chip T1 die-bonded first as shown in FIG. The substrate 11 is preliminarily coated with an adhesive 13 that bonds the substrate 11 and the LED chip.
[Example 2]
FIG. 3 is a schematic cross-sectional view showing the form of an LED chip die-bonded by the method of the present invention, and FIG. 4 is a plan view of FIG. 3 viewed from the emission observation surface side. In this embodiment, as in the first embodiment, LED chips having two types of thickness are die-bonded. First, the thinner LED chip T1 is die-bonded on the substrate 11. Next, the thicker LED chip T2 is die-bonded so as to form a zigzag shape with the LED chip T1 previously die-bonded as shown in FIGS.
[Example 3]
FIG. 5 is a schematic cross-sectional view showing the form of an LED chip die-bonded by the method of the present invention. In the present embodiment, as shown in FIG. First, the LED chip T3 is die-bonded to the concave portion of the substrate 11, and then the LED chip T3 is die-bonded to the convex portion.
[0013]
In any of the first to third embodiments, when the LED chip is die-bonded, the die bonder collet 12 does not contact the previously die-bonded LED chip, and the LED chips can be close-bonded to each other. Can be die-bonded on the same substrate with high density.
[Example 4]
FIG. 6 is a schematic cross-sectional view showing the form of an LED chip die-bonded by the method of the present invention. There are three types of LED chips that are die-bonded in this embodiment: green LED chip T4, blue LED chip T5, and red LED chip T6. The thickness of these three types of LED chips is 80 μm for green and blue, and 150 μm for red. is there. Of these LED chips, the thinner one, that is, the green LED chip T4 and the blue LED chip T5 are die-bonded first. Next, the red LED chip T6 is die-bonded between the green LED chip T4 and the blue LED chip T5 to obtain a chip form as shown in FIG.
[0014]
In the present embodiment, a plurality of LED chips can be die-bonded at a high density on the same substrate as in the first to third embodiments. Therefore, the multi-color light emitting LED obtained by electrically connecting the die-bonded LED chip to the substrate can not only easily set the light distribution characteristics as in the above embodiment, but also the LED chip having a different light emission color can be set high. Since it is die-bonded at a density, the color mixture of light emitted from the LED chips of the respective light emission colors is improved and color unevenness does not occur.
[0015]
In this embodiment, two types of LED chips having a thickness are used, but three or more types of LED chips may be used, and the unevenness provided on the substrate may be multistage. In addition, the LED chip has three colors of red, green, and blue, but is not particularly limited. The die bonding method of the present invention can be applied to all cases in which two or more LED chips are die bonded.
【The invention's effect】
[0016]
As described above, according to the die-bonding method of the present invention, when the LED chip is die-bonded, a plurality of LED chips are die-bonded with high density without the die bonder collet contacting the previously die-bonded LED chip. The light source can be made closer to a point light source than in the past. Therefore, the LED obtained by using the present invention can easily set the light distribution characteristics because the light source is not discrete but close to a point light source. In addition, since the LED chip is closely die-bonded in the present invention, the space required for the die-bonding can be reduced, and the LED can be downsized.
[0017]
In addition, a multicolor light emitting LED in which LED chips having different light emitting colors are die-bonded has an advantage that the degree of color mixing of light emitted from each LED chip is increased, and color unevenness and variation in light emitting characteristics can be prevented.
[Brief description of the drawings]
[0018]
FIG. 1 is a schematic cross-sectional view illustrating the present invention.
FIG. 2 is a schematic cross-sectional view showing the form of an LED chip for explaining an embodiment of the present invention.
FIG. 3 is a schematic cross-sectional view showing the form of an LED chip for explaining an embodiment of the present invention.
FIG. 4 is a plan view showing the form of an LED chip for explaining an embodiment of the present invention.
FIG. 5 is a schematic cross-sectional view showing the form of an LED chip for explaining an embodiment of the present invention.
FIG. 6 is a schematic cross-sectional view showing the form of an LED chip for explaining an embodiment of the present invention.
FIG. 7 is a schematic cross-sectional view for explaining a conventional die bonding method.
[Explanation of symbols]
[0019]
11 .... Substrate 12 .... Die bonder collet 13 .... Adhesive

Claims (2)

In a die bonding method of die bonding a plurality of LED chips to a substrate,
The plurality of LED chips are LED chips having different thicknesses, and the distance between the LED chip that has been previously die-bonded and the LED chip that is later die-bonded is the end of the die bond collet that sucks and conveys the LED chip that is later die-bonded. And the distance between the LED chip to be die-bonded after that, and
A die bonding method for an LED chip, characterized in that a thin LED chip is die-bonded before a thick LED chip die-bonded between the thin LED chips.   The LED chip die-bonding method according to claim 1, wherein the plurality of LED chips include two or more kinds of LED chips having different emission colors.

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