JP2007311401A - Led light emitting device and method of fabricating the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an LED light emitting device in which extraction efficiency of light from an LED chip is enhanced and deterioration due to heat generation or a short wavelength region (UV region) is suppressed. <P>SOLUTION: In an LED light emitting device 1; semiconductor layers 14, 15 and 16 are formed on a substrate 13, and an LED chip 12 having an n-electrode 17 and a p-electrode 18 formed on the semiconductor layers 14, 15 and 16 is bonded to a base mount 11. A light reflection layer 22 composed of a material having a photoreflectance higher than that of the surface layers 11a, 11b and 11c of the base mount 11 is formed on the base mount 11, and the LED chip 12 is bonded onto the light reflection layer 22 through transparent silicon based adhesive 21 not containing filler. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an LED light emitting device in which a semiconductor layer is formed on a substrate and an LED chip having an n electrode and a p electrode formed on the semiconductor layer is bonded to a base.

  As a conventional LED light emitting device 10, for example, there is a device as shown in FIG. 9 (see, for example, Patent Document 1). An LED light emitting device 10 shown in FIG. 9 is obtained by bonding an LED chip 12 on a lead frame 110. In the LED chip 12, a semiconductor layer is formed by sequentially laminating an n-type layer 14, a light-emitting layer 15, and a p-type layer 16 on a light-transmitting substrate 13 such as sapphire. The n-type layer 14 is formed in a staircase shape, and an n-electrode 17 is provided on the lower stage and a light emitting layer 15 and the like are stacked on the upper stage. A p-type electrode 18 having translucency is provided on the upper surface of the p-type layer 16, a pad 19 is provided on the p-type electrode 18, and a wire 20 is bonded to the n-type electrode 17 and the pad 19. The LED chip 12 configured as described above is bonded onto the lead frame 110 with an adhesive 21 ′. As the adhesive 21 ', an epoxy adhesive mixed with a filler is used. The filler is made of a material having a reflection effect and a heat dissipation effect, and a typical example thereof is Ag.

  In the conventional LED light emitting device 10, the light generated in the light emitting layer 15 is emitted to the p electrode 18 side and the light transmissive substrate 13 side. The light emitted to the p-electrode 18 side passes through the p-electrode 18 and is emitted to the outside. On the other hand, the light emitted to the light transmissive substrate 13 side passes through the light transmissive substrate 13 and reaches the adhesive 21 ′, is reflected by the filler mixed in the adhesive 21 ′, and is emitted to the outside. Further, the heat generated in the LED chip 12 is transmitted to the lead frame 110 by the filler mixed in the adhesive 21 ′ and is radiated from the lead frame 110.

JP 2000-58914 A

  However, since the conventional LED light emitting device has the LED chip and the base bonded with an epoxy adhesive mixed with a filler, the light emitted from the light emitting layer passes between the filler particles or the filler particles. Or irregular reflection. As a result, there is a concern that the reflection efficiency and the luminous flux are reduced, and the performance of the LED chip is suppressed.

  In addition, when an epoxy adhesive is used, the LED chip easily deteriorates (discolors) due to the heat generated by the LED chip. When a short wavelength LED chip such as a blue LED is used, light in the ultraviolet region is absorbed and deteriorated ( Easy to discolor). When the adhesive is deteriorated, the light emitted from the light emitting layer is hardly transmitted, and the reflection efficiency is further reduced.

  The present invention was devised in view of such problems, and its purpose is to improve the light extraction efficiency from the LED chip, and to suppress the deterioration due to the effects of heat generation and short wavelength region (ultraviolet region) The object is to provide a light emitting device and a method for manufacturing the same.

  In order to achieve the above object, an LED light-emitting device according to the present invention is formed by adhering to a base an LED chip in which a semiconductor layer is formed on a substrate and an n-electrode and a p-electrode are formed on the semiconductor layer. A light reflecting layer made of a material having a higher light reflectance than the surface layer of the base is formed on the base, and the LED is formed on the light reflecting layer with a transparent silicon adhesive that does not contain a filler. The substrate side of the chip is bonded to the light reflecting layer.

  In the LED light emitting device according to the present invention, as described above, the LED chip is bonded to the light reflecting layer with a transparent silicon-based adhesive that does not contain a filler. The light emitted to the light passes through the transparent silicon-based adhesive, reaches the light reflecting layer, and is reflected on the opposite side of the substrate. Thereby, the reflection efficiency and the luminous flux can be improved, and the performance of the LED chip can be sufficiently exhibited. In addition, since the silicon-based adhesive has a thermal conductivity higher than that of the epoxy-based adhesive and is not easily affected by the short wavelength region, the life of the LED light emitting device can be extended.

  The LED light emitting device according to the present invention is characterized in that the substrate is a transparent substrate. As described above, when the substrate is configured to be transparent, since the space between the light emitting layer and the light reflecting layer in the semiconductor layer of the LED chip is configured to be transparent, the light emitted from the light emitting layer toward the light reflecting layer is not generated. It is difficult to attenuate, and is reflected by the light reflecting layer and efficiently emitted to the outside of the LED light emitting device.

  An LED light emitting device manufacturing method according to the present invention includes an LED chip in which a semiconductor layer is formed on a substrate and an n electrode and a p electrode are formed on the semiconductor layer, and a material having a higher light reflectance than the surface layer. A preparation step of preparing a base on which a light reflecting layer is formed, an application step of applying a transparent silicon-based adhesive not containing a filler to a predetermined region on the light reflecting layer of the base, and a predetermined region of the base A bonding step of pressing and bonding the LED chip through a transparent silicon-based adhesive.

  The manufacturing method of the LED light-emitting device according to the present invention, as described above, applies a transparent silicon-based adhesive in a coating process to a predetermined region on the light reflecting layer of the base prepared in the preparation process, and the bonding process. When the LED chip is pressed and adhered to a predetermined area of the base via a transparent silicon adhesive, the silicon adhesive protrudes to the side surface of the light emitting layer in the semiconductor layer of the LED chip due to a manufacturing error. There is. Thus, even if the silicon adhesive protrudes to the side surface of the light emitting layer of the LED chip, since the silicon adhesive is transparent, the LED light emitting device that can emit reflected light while suppressing the attenuation of light on the side of the LED chip. Is obtained.

  Further, in the method of manufacturing the LED light emitting device according to the present invention, a plurality of LED chips are bonded to a predetermined region on the light reflecting layer of the base via a transparent silicon adhesive that does not include a filler. It includes a covering step of covering a plurality of LED chips with a resin.

  In the above LED light emitting device manufacturing method, a plurality of LED chips arranged on the light reflecting layer of the base are covered with a predetermined resin, so that the LED chip is directly or laterally bonded from the side of the LED chip. The light emitted indirectly through the agent can be reflected also by the light reflecting layer formed in the region between the LED chips, and an LED light emitting device in which the surface of a predetermined resin emits light uniformly is obtained. It is done.

  Furthermore, in the manufacturing method of the LED light emitting device according to the present invention, an electrode member is formed between positions where the plurality of LED chips are bonded to the base prepared in the preparation step, and the LED The height of the light emitting layer in the semiconductor layer of the chip is formed higher than the electrode member, and each of the plurality of LED chips and the electrode member are connected by a wire between the bonding step and the covering step. A wire connecting step.

  The manufacturing method of the LED light emitting device described above is such that the height of the light emitting layer in the semiconductor layer of the LED chip is made higher than that of the electrode member, so that the silicon-based adhesive reaches the side surface of the light emitting layer in the semiconductor layer of the LED chip. Even if it protrudes, the electrode member between the LED chips can be illuminated using the light emitted from the side of the LED chip obtained by making the adhesive transparent, and the surface of the predetermined resin emits uniformly. An LED light emitting device is obtained.

  According to the present invention, since the LED chip and the base are bonded with a transparent silicon-based adhesive having excellent thermal conductivity, the heat generated in the LED chip can be efficiently radiated, and the LED light emission. The lifetime of the device can be extended. In addition, since the silicon adhesive is transparent, the light emitted from the LED chip to the base side is transmitted and reflected by the light reflecting layer formed on the base, thereby increasing the reflection efficiency and luminous flux. Can do.

  Further, according to the method of the present invention, the silicon adhesive is transparent even if the silicon adhesive protrudes to the side surface of the light emitting layer in the semiconductor layer of the LED chip due to a manufacturing error. An LED light-emitting device that can emit reflected light while suppressing the attenuation of the light is obtained.

  Hereinafter, an embodiment of an LED light emitting device according to the present invention will be described with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected to the site | part same as a prior art example, and detailed description is abbreviate | omitted.

  FIG. 1 is a longitudinal sectional view showing an embodiment of an LED light emitting device 1 according to the present invention. In the LED light emitting device 1, a light reflecting layer 22 made of a material having a light reflectance higher than that of the surface of the base 11 is formed on the base 11, and transparent silicon not containing a filler is formed on the light reflecting layer 22. The LED chip 12 is bonded with a system adhesive 21. The LED chip 12 has the same configuration as that of the conventional example, and the same parts as those of the conventional example are denoted by the same reference numerals and detailed description thereof is omitted. Note that the substrate 13 of the LED chip 12 is preferably made of only sapphire.

  The base 11 is a laminated substrate in which a Mo layer 11b is interposed between the Cu layers 11a and 11c, and has a thermal expansion coefficient substantially equal to that of sapphire constituting the substrate 13 of the LED chip 12. When the thermal expansion coefficients of the surface layer of the base 11 and the substrate 13 of the LED chip 12 are substantially equal, the heat generated in the LED chip 12 can be easily radiated to the base 11. Note that the base 11 is not limited to a laminated substrate, and may have other configurations such as a configuration similar to the conventional example (a lead frame made of a single layer substrate).

  The light reflecting layer 22 is made of white AgPt, and its surface is flat. AgPt constituting the light reflecting layer 22 is a material having a light reflectance higher than that of the Cu layer 11 a serving as the surface of the base 11. Examples of the material having a light reflectance higher than that of the Cu layer 11a serving as the surface of the base 11 include Ag as well as AgPt. White AgPt is a material having a higher light reflectance than gray Ag.

  The silicon-based adhesive 21 is a transparent material that does not include a filler such as Ag, and is excellent in thermal conductivity to the same level or more as an epoxy-based paste that does not include a filler such as Ag.

  The LED light emitting device 1 of this embodiment is configured as described above, and light is emitted upward and downward in the drawing from the light emitting layer 15 of the LED chip 12 itself. The upward light is transmitted to the outside through the p-electrode 18 having translucency. The downward light passes through the sapphire substrate 13 and the transparent silicon adhesive 21 to reach the light reflecting layer 22, is reflected by the light reflecting layer 22, and turns upward to change the silicon adhesive 21 and the LED chip. 12 is emitted to the outside. Reflecting downward light with the flat light reflection layer 22 makes it difficult to diffusely reflect, thereby improving the reflection efficiency and the luminous flux. Even if the base 11 is made of Ag or AgPt without providing the light reflecting layer 22, it is possible to enjoy the same reflecting action as in the above embodiment, but the cost is reduced by providing the light reflecting layer 22. can do.

  Further, heat generated in the LED chip 12 is radiated to the base 11 through the silicon adhesive 21. The silicon-based adhesive 21 is superior in thermal conductivity to the same level or more as an epoxy-based paste that does not contain a filler such as Ag, and is not easily deteriorated by heat. Furthermore, the silicon-based adhesive 21 is unlikely to deteriorate (discolor) in a short wavelength region such as a blue LED. Thus, the lifetime of the LED light-emitting device 1 can be extended by using the silicon-based adhesive 21 that is not easily affected by the heat generation of the LED chip 12 and the short wavelength region (ultraviolet region). In addition, since the thermal expansion coefficients of the surface layer of the base 11 and the substrate 13 of the LED chip 12 are substantially equal, heat generated in the LED chip 12 is easily transmitted to the base 11 and suppresses deterioration due to heat generation of the LED chip 12. You can also

  As described above, one embodiment of the LED light emitting device 1 according to the present invention has been described. However, the present invention is not limited to the above embodiment, and various modifications can be made. For example, in the above embodiment, in order to improve the heat dissipation of the LED chip 12, the thermal expansion coefficients of the surface layer of the substrate 13 and the base 11 are made substantially equal. However, as shown in FIG. The heat dissipation of the base 11 can also be improved by using 23. The cylindrical heat dissipating member 23 is made of a metal material such as aluminum, and air convection is generated therein, so that heat dissipation is improved. Further, heat can be radiated through the swan-type base module 24 shown in FIG. 3 or the Edison-type base module 25 shown in FIG. 3 and 4, the LED light emitting device 1 is mounted on the LED device main body 26 and modularized as an LED module 27. By modularizing in this way, various types of caps can be handled. Inside the swan-type base module 24 and the Edison-type base module 25, a current limiting resistor or the like is provided.

  Next, a manufacturing method of the LED light emitting device 1 described above will be described with reference to FIGS.

  FIG. 5 shows the base 11 prepared in the preparation step which is one step of the method of the present invention. A light reflecting layer 22 is formed on the surface of the base 11, and an electrode member 23 is disposed on the light reflecting layer 22. The electrode member 23 has a wiring pattern 23a made of a conductive material such as gold or copper provided on the upper surface of an electrode member main body 23b formed of ceramic or the like. Moreover, the electrode member 23 is arrange | positioned between the positions where the some LED chip on the base 11 is adhere | attached. Here, the light emitting layer 15 in the semiconductor layer of the LED chip 12 is higher than the electrode member 23. That is, as the electrode member 23, one lower than the light emitting layer 15 in the semiconductor layer of the LED chip 12 is used.

  FIG. 6 is a schematic view showing a coating process which is one process of the method of the present invention. In the application step, the silicon-based adhesive 21 is applied to a predetermined region (location where the LED chip 12 is disposed) on the light reflecting layer 22 of the base 11.

  FIG. 7 is a schematic view showing an adhesion step which is one step of the method of the present invention. The LED chip 12 is taken out from the semiconductor wafer by a die bonder (not shown), and the LED chip 12 is pressed and adhered to the application site of the silicon adhesive 21 on the base 11. Although the LED chip 12 in FIG. 7 is shown in a simplified manner, it is the same as that shown in FIG.

  FIG. 8 is a schematic view showing an example of the LED light emitting device 1 obtained by the method of the present invention. After the bonding process, a wire connecting process and a covering process are performed. The wire connection step is so-called wire bonding, and is a step of connecting each of the plurality of LED chips 12 and the electrode member 23 with the wire 20. After the wire connecting step, a covering step of covering the plurality of LED chips 12 with a predetermined resin 24 is performed, and the LED light emitting device 1 shown in FIG. 8 is obtained.

  Here, as shown in FIGS. 7 and 8, when an adhesion process is performed in which the LED chip 12 is pressed and adhered to the silicon-based adhesive 21 applied to a predetermined region on the base 11, the silicon-based adhesive 21. May protrude from the side surface of the LED chip 12. The portion where the silicon adhesive 21 protrudes is referred to as a side wall 21a. The side wall 21a may be caused by a manufacturing error such as a deviation in the application amount or application position of the silicon-based adhesive 21 or a positional deviation in the LED chip 12, or may be intentionally formed to increase the adhesion strength of the LED chip 12. Or Manufacturing errors are likely to occur in the side wall 21a. For example, the right side LED chip 12 in FIGS. 7 and 8 is formed so that the side wall 21a surrounds the lower part of the LED chip 12, but the left side LED chip 12 has the side wall 21a. Most of the side surfaces of the LED chip 12 are covered. Thus, when the side wall 21a covers most of the side surfaces of the LED chip 12, if a conventional adhesive containing a filler is used, it becomes difficult for light to be emitted from the side of the LED chip 12. In contrast, in the present invention, since the transparent silicon-based adhesive 21 containing no filler is used, even if the side wall 21a covers most of the side surface of the LED chip 12, the side of the LED chip 12 is used. Light can be emitted. Further, when the side wall 21a is large enough to contact the two electrodes 17 and 18 of the LED chip 12, if a conventional adhesive containing a filler is used, the electrodes 17 and 18 are short-circuited. Since the transparent silicon-based adhesive 21 containing no filler is used, the electrodes 17 and 18 do not short-circuit.

  In FIG. 8, the height h <b> 2 of the light emitting layer 15 of the LED chip 12 is higher than the height h <b> 1 of the electrode member 23. Thereby, regardless of whether the side wall 21 a covers the side of the light emitting layer 15, the light emitted from the light emitting layer 15 is reflected by the electrode member 23 and emitted from the front surface of the LED light emitting device 1. Therefore, the LED light emitting device 1 with stable quality can be obtained. If the predetermined resin 24 contains a phosphor, the light from the LED chip 12 can be changed to a desired color by changing the color of the phosphor.

It is a longitudinal cross-sectional view which shows one Embodiment of the LED light-emitting device which concerns on this invention. It is a perspective view which shows the 1st modification of the LED light-emitting device which concerns on this invention. It is a longitudinal cross-sectional view which shows the 2nd modification of the LED light-emitting device which concerns on this invention. It is a longitudinal cross-sectional view which shows the 3rd modification of the LED light-emitting device which concerns on this invention. It is the schematic which shows an example of the base prepared in the preparatory process which is one process of the manufacturing method of the LED light-emitting device which concerns on this invention. It is the schematic which shows an example of the application | coating process which is 1 process of the manufacturing method of the LED light-emitting device which concerns on this invention. It is the schematic which shows an example of the adhesion process which is one process of the manufacturing method of the LED light-emitting device which concerns on this invention. It is the schematic which shows an example of the LED light-emitting device obtained by the manufacturing method of the LED light-emitting device which concerns on this invention. It is a longitudinal cross-sectional view which shows an example of the conventional LED light-emitting device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 LED light-emitting device 11 Base 11a, 11cCu layer 11b Mo layer 12 LED chip 13 Board | substrate 14 n-type layer 15 Light-emitting layer 16 p-type layer 17 n-electrode 18 p-electrode 19 Pad 20 Wire 21 Silicon type adhesive agent 22 Light reflection layer 23 Electrode member 24 Predetermined resin

Claims (5)

An LED light emitting device formed by adhering an LED chip having a semiconductor layer formed on a substrate and an n electrode and a p electrode formed on the semiconductor layer to a base,
A light reflecting layer made of a material having a higher light reflectance than the surface layer of the base is formed on the base, and the substrate side of the LED chip is formed on the light reflecting layer with a transparent silicon-based adhesive that does not contain a filler. Is bonded to the light reflecting layer.   The LED light-emitting device according to claim 1, wherein the substrate is made of a transparent substrate. An LED chip in which a semiconductor layer is formed on a substrate and an n electrode and a p electrode are formed on the semiconductor layer, and a base on which a light reflecting layer made of a material having a light reflectance higher than that of the surface layer is formed are prepared. A preparation process;
An application step of applying a transparent silicon-based adhesive not containing a filler in a predetermined region on the light reflecting layer of the base;
And a bonding step of pressing and bonding the LED chip to a predetermined region of the base via a transparent silicon-based adhesive.   A plurality of LED chips are bonded to a predetermined region on the light reflection layer of the base via a transparent silicon adhesive that does not include a filler, and includes a covering step of covering the plurality of LED chips with a predetermined resin. The manufacturing method of the LED light-emitting device of Claim 3 characterized by these. In the base prepared in the preparation step, an electrode member is formed between positions where the plurality of LED chips are bonded, and the height of the light emitting layer in the semiconductor layer of the LED chip is an electrode. It is formed higher than the member,
5. The method of manufacturing an LED light-emitting device according to claim 4, further comprising a wire connecting step of connecting each of the plurality of LED chips and the electrode member with a wire between the bonding step and the covering step. .