JP2015144301A - optical semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical semiconductor device with a high heat dissipation property.SOLUTION: An optical semiconductor device comprises: a tabular substrate 1 with an LED chip mounted thereon; a sealing resin layer 2 in which the LED chip is buried; an inorganic high-heat conduction layer 3; and a wavelength conversion layer 4 including inorganic phosphor powder. In the optical semiconductor device, the sealing resin layer, the inorganic high-heat conduction layer, and the wavelength conversion layer are directly or indirectly stacked on the substrate in this order; the inorganic high-heat conduction layer has a thickness of 10-1000 μm. The optical semiconductor device can be preferably used in high-power applications including a general luminaire using LED as a light emission source, a backlight of a display, and a head light of a motor vehicle.

Description

  The present invention relates to an optical semiconductor device. More specifically, the present invention relates to an optical semiconductor device having an LED (light emitting diode) and excellent in heat dissipation.

  In recent years, white light emitting diodes (LEDs) have attracted attention as a new illumination light source that achieves significant energy savings. The white LED device is obtained by combining a GaN LED chip that emits blue light and a phosphor that emits light having a wavelength different from that of the LED when excited by light emitted from the LED chip.

  Recently, white LEDs for high power applications such as general lighting and special lighting such as automobile headlights are being developed. In the high power white LED, local heat generation of the wavelength conversion member is a problem, and various studies have been made on the heat dissipation of the LED.

  For example, in Patent Document 1, the lens cover of the LED chip is made of a material that does not contain an organic material, whereby the heat resistance of the lens cover is improved and the thermal conductivity is relatively high, 0.9 W / mK or more. It is said. Moreover, in patent document 2, the usage-amount can be reduced compared with the case where a light-diffusion material is disperse | distributed to the whole wavelength conversion member by arrange | positioning a light-diffusion material in the specific position of a color conversion member (wavelength conversion member), In addition, the concentration of the LED light flux is relaxed, and local heat generation of the wavelength conversion member is suppressed.

JP 2007-250817 A JP 2009-130299 A

  The lens cover described in Patent Document 1 has a thermal conductivity of 0.9 W / mK or more, but is still unsatisfactory for high-power LED applications. Moreover, since the color conversion member (wavelength conversion member) described in Patent Document 2 includes phosphor particles and a light diffusion material, it cannot be said that the thermal conductivity is sufficiently high. Therefore, an optical semiconductor device that is further excellent in heat dissipation is required.

  The subject of this invention is providing the optical semiconductor device with high heat dissipation.

  The present invention comprises a flat substrate on which an LED chip is mounted, a sealing resin layer in which the LED chip is embedded, an inorganic high thermal conductive layer, and a wavelength conversion layer containing an inorganic phosphor powder. In the optical semiconductor device, a sealing resin layer, an inorganic high thermal conductive layer, and a wavelength conversion layer are laminated directly or indirectly in this order on the substrate, and the thickness of the inorganic high thermal conductive layer Relates to an optical semiconductor device having a thickness of 10 to 1000 μm.

  Since the optical semiconductor device of the present invention is excellent in heat dissipation, it can be suitably used as a high-power white LED device.

FIG. 1 is a diagram showing an example of an optical semiconductor device of the present invention. FIG. 2 is a diagram showing a specific state of one aspect of the method for manufacturing an optical semiconductor device of the present invention. The left is a state in which the wavelength conversion layer containing the constituent resin solution, the inorganic high thermal conductive layer, and the inorganic phosphor powder is embedded in the concave mold, and the inside is sealed. The right side is a diagram showing a state in which the concave mold is removed.

  An optical semiconductor device of the present invention includes a substrate on which an LED chip is mounted, a sealing resin layer in which the LED chip is embedded, an inorganic high thermal conductive layer, and a wavelength conversion layer containing an inorganic phosphor powder. The sealing resin layer, the inorganic high thermal conductive layer, and the wavelength conversion layer are laminated directly or indirectly in this order on the substrate. In this specification, the state in which the sealing resin layer, the inorganic high thermal conductive layer, and the wavelength conversion layer are “directly laminated” means that the inorganic high thermal conductive layer and the wavelength conversion layer are in this order on the sealing resin layer. It represents the state of direct lamination or arrangement, and the state of “indirect lamination” means between the sealing resin layer and the inorganic high thermal conductive layer and / or between the inorganic high thermal conductive layer and the wavelength conversion layer. A state in which the layers are stacked or arranged via any other resin layer (for example, a resin layer containing photonucleic acid particles).

  When the inorganic phosphor is excited by light emitted from the LED chip, it emits wavelength-converted light. At that time, the loss energy of the inorganic phosphor is absorbed by the wavelength conversion layer, and the temperature of the wavelength conversion layer rises. However, if there is a layer having a low thermal conductivity around the wavelength conversion layer, the heat of the wavelength conversion layer is not diffused. As a result, the temperature of the optical semiconductor device is increased, and the sealing material, etc. Will lead to deterioration. On the other hand, from the viewpoint of improving the luminance of the device, the wavelength conversion layer is preferably located in the outermost layer of the sealing portion including the wavelength conversion layer and the sealing resin layer. Therefore, in the present invention, a heat conductive layer composed of an inorganic material having high heat conductivity is provided between the wavelength conversion layer and the sealing resin layer that embeds the LED chip. That is, the heat generated in the wavelength conversion layer is conducted in order from the heat conductive layer to the sealing resin layer and the substrate to facilitate heat dissipation, thereby improving the heat dissipation of the optical semiconductor device, and thus the sealing portion. It is considered that the durability of the apparatus is improved by suppressing the deterioration of the apparatus.

  The structure of the optical semiconductor device of the present invention will be described with reference to FIG. In the following description, the sealing resin layer, the inorganic high thermal conductive layer, and the wavelength conversion layer may be collectively referred to as a sealing portion in the optical semiconductor device of the present invention.

  1 in FIG. 1 indicates a substrate on which an LED chip is mounted.

  The LED chip (optical semiconductor element) in the present invention is not particularly limited as long as it is usually used in an optical semiconductor device. For example, gallium nitride (GaN, refractive index: 2.5), gallium phosphide (GaP, refractive index: 2.9), gallium arsenide (GaAs, refractive index: 3.5) and the like. Among these, GaN emits light in the ultraviolet to visible blue region, and from the viewpoint that a white LED can be manufactured through a phosphor. Is preferred.

  The substrate on which the LED chip is mounted is not particularly limited, and examples thereof include a metal substrate, a rigid substrate in which copper wiring is laminated on a glass-epoxy substrate, and a flexible substrate in which copper wiring is laminated on a polyimide film. Any form such as a plate can be used.

  As a mounting method of the LED chip on the substrate, a face-up mounting method suitable for mounting an LED chip having an electrode disposed on a light emitting surface, an LED chip having an electrode disposed on a surface opposite to the light emitting surface is used. A flip lip mounting method suitable for mounting can be mentioned.

  1 in FIG. 1 indicates a sealing resin layer in which an LED chip is embedded.

  The resin constituting the sealing resin layer is not particularly limited as long as it is a resin conventionally used for optical semiconductor sealing, and examples thereof include thermosetting transparent resins such as silicone resins and epoxy resins. It can be used in combination of two or more species. Of these, silicone resins are preferred from the viewpoints of heat resistance and light resistance. These resins may be commercial products or may be synthesized according to known methods.

  In the present invention, light diffusing particles may be dispersed in the sealing resin layer from the viewpoint of improving light diffusibility.

  Examples of the light diffusing particles include transparent inorganic fine particles such as silica, titania, and alumina. Among these, since the diffusion effect increases as the refractive index increases, inorganic fine particles having a refractive index of preferably 1.4 or more, for example, silica fine particles are preferable.

  The average particle diameter of the light diffusing particles is preferably 0.5 to 60 μm, more preferably 1.0 to 50 μm, from the viewpoint of suppressing backward light scattering loss. The shape of the light diffusing particles is preferably spherical in order to suppress light loss due to light diffusion. In addition, in this specification, the average particle diameter of particle | grains can be measured by the method as described in the below-mentioned Example.

  When the content of the light diffusing particles in the sealing resin layer is preferably 1% by weight or more, more preferably 10% by weight or more, the heat dissipation is improved. Further, the transparency of the sealing resin layer is excellent when it is preferably 70% by weight or less, more preferably 60% by weight or less. Accordingly, the content of the light diffusing particles in the sealing resin layer is preferably 1 to 70% by weight, and more preferably 10 to 60% by weight.

  In addition to the above, the encapsulating resin layer in the present invention includes additives such as a curing agent, a curing accelerator, an anti-aging agent, a modifier, a surfactant, a dye, a pigment, a discoloration inhibitor, and an ultraviolet absorber. Can be contained.

  The sealing resin layer may be a commercially available product or may be synthesized according to a known method. For example, when the constituent resin is liquid, the LED chip is sealed at the time of manufacturing the optical semiconductor device. The sealing resin layer may be formed by forming the constituent resin and, if necessary, the constituent resin in which the light diffusing particles are dispersed into layers by heating during processing.

  The thickness of the sealing resin layer is preferably 300 to 5000 μm, more preferably 500 to 3000 μm, from the viewpoints of heat resistance and LED chip sealing properties.

  1 in FIG. 1 indicates an inorganic high thermal conductive layer, and the inorganic high thermal conductive layer means a layer having high thermal conductivity composed of an inorganic material, and essentially consists of an inorganic material having high thermal conductivity. It is a heat conductive layer.

  The inorganic material constituting the inorganic high thermal conductive layer is not particularly limited as long as it exhibits high thermal conductivity. For example, yttrium aluminate (not containing an activator such as YAG and Ce), translucency such as glass, etc. Ceramics may be mentioned.

  The layer composed of the inorganic material may be a commercially available product or may be synthesized according to a known method. For example, additives such as a binder resin, a dispersant, and a sintering aid are added to a desired inorganic material, wet-mixed in the presence of a solvent to prepare a slurry solution, and then the resulting slurry solution is molded. It can be produced by heating and sintering. As the additive such as the binder resin, the dispersant, and the sintering aid, those known in the art can be used without particular limitation as long as they are decomposed and removed by heat sintering. Moreover, as long as the effect of this invention is not impaired, the said raw material may be mixed in the heat conductive layer, However, It is more preferable to remove completely by heat sintering.

  The thickness of the inorganic high heat conductive layer is preferably 10 to 1000 μm, more preferably 30 to 800 μm, from the viewpoint of heat dissipation.

  The thermal conductivity of the obtained inorganic high thermal conductive layer is preferably 1 W / mK or more, and more preferably 10 W / mK or more because it leads to heat dissipation of the optical semiconductor device.

  In the present invention, from the viewpoint of reducing the overall amount of the inorganic material constituting the inorganic high heat conductive layer, although it cannot be said unconditionally depending on the size of the optical semiconductor device, the inorganic high heat conductive layer is, for example, In addition, preferably 2 to 20 mm x 2 to 20 mm (square) x 0.05 to 1 mm (high), more preferably 5 to 15 mm x 5 to 15 mm (square) x 0.10 to 0.8 mm (high) Good.

  1 in FIG. 1 indicates a wavelength conversion layer containing inorganic phosphor powder. Since the wavelength conversion layer is in the outermost layer of the sealing portion, the optical semiconductor device of the present invention can increase the light extraction efficiency from the LED chip.

  Examples of the resin constituting the wavelength conversion layer include the same resins as those constituting the sealing resin layer. Of these, silicone resins are preferred from the viewpoints of heat resistance and light resistance. These resins may be commercial products or may be synthesized according to known methods.

  The inorganic phosphor is not particularly limited as long as it can convert light emitted from the LED chip into light having a wavelength longer than the wavelength, and a known phosphor conventionally used in optical semiconductor devices is used. be able to. Specifically, YAG, TAG, α-sialon and the like are exemplified as suitable commercially available phosphors having a function of converting blue to yellow.

  The inorganic phosphor powder is not particularly limited as long as the inorganic phosphor is in a powder form, but from the viewpoint of the quantum efficiency and light scattering property of the phosphor, the average particle diameter of the powder is 0.1 ˜200 μm is preferable, and 1 to 50 μm is more preferable.

  The content of the inorganic phosphor powder in the wavelength conversion layer is not generally determined because the degree of whitening varies depending on the type of phosphor and the thickness of the wavelength conversion layer, but is preferably 1 to 70% by weight, 10 to 60 Weight percent is more preferred.

  In addition to the above, the wavelength conversion layer in the present invention contains additives such as a curing agent, a curing accelerator, an anti-aging agent, a modifier, a surfactant, a dye, a pigment, a discoloration inhibitor, and an ultraviolet absorber. can do.

  The wavelength conversion layer may be a commercially available product or may be synthesized according to a known method. For example, the resin solution containing the inorganic phosphor powder is coated on a release sheet (for example, a polyethylene base material) whose surface is peeled off to an appropriate thickness using an applicator or the like, and at an arbitrary temperature. A wavelength conversion layer can be formed by heating and drying.

  The thickness of the wavelength conversion layer is preferably 50 to 1000 μm and more preferably 100 to 300 μm from the viewpoint of heat dissipation.

  The area of the wavelength conversion layer is preferably 2 to 20 mm × 2 to 20 mm (square), and more preferably 5 to 15 mm × 5 to 15 mm (square). In the present invention, the sealing resin layer, the inorganic high thermal conductive layer, and the wavelength conversion layer may have different thicknesses, but preferably have the same size (area).

  As described above, the optical semiconductor device of the present invention has the above-described configuration. Next, a method for manufacturing the optical semiconductor device of the present invention will be described with reference to FIG. Therefore, the present invention also provides a method for manufacturing an optical semiconductor device of the present invention.

  First, a sealing part is installed in the concave mold (see the left figure in FIG. 2). That is, the wavelength conversion layer and the inorganic high thermal conductive layer are formed in this order on the bottom of the concave mold. At this time, even if the wavelength conversion layer and the inorganic high thermal conductive layer are each prepared in advance in the form of a layer, the size is adjusted to the size of the bottom of the concave mold, and then placed, the resin solution for constituting the wavelength conversion layer An inorganic high thermal conductive layer prepared separately may be laminated after forming the wavelength conversion layer by injecting into the bottom of the concave mold and drying by heating. Thereafter, when the constituent resin of the sealing resin layer is in a liquid state, for example, the constituent resin solution is filled after dispersing the light diffusing particles as necessary.

  Next, the substrate on which the LED chip is mounted is placed so that the filled sealing resin layer and the LED chip face each other, and then sealed (see the middle diagram of FIG. 2). The heating temperature for the sealing process is preferably 80 to 200 ° C, and more preferably 80 to 150 ° C. The heating time is preferably 0.5 to 10 minutes, more preferably 0.5 to 5 minutes. From the viewpoint of preventing air bubbles from entering the sealing resin layer, the sealing process can be performed under reduced pressure.

  Thereafter, the molded package is allowed to stand until the shape does not change even at room temperature, and then the mold is removed to obtain the optical semiconductor device of the present invention (see the right diagram in FIG. 2). In addition, you may post-cure by heating and pressurizing to the time required for hardening of the sealing resin layer.

  The optical semiconductor device of the present invention thus obtained has a light transmittance of 90% or more with respect to incident light in the visible light range of 380 to 780 nm. Therefore, even if an inorganic high thermal conductive layer is laminated, it can be used as a white LED device. It is preferable because there is no decrease in luminance.

  EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, a comparative example, and a reference example, this invention is not limited at all by these Examples.

[Average particle diameter of light diffusing particles and inorganic phosphor]
The average particle size of the light diffusing particles and the inorganic phosphor is the average particle size of the primary particles of the light diffusing particles and the inorganic phosphor, and the diameter of 100 particles shown in the image by a transmission electron microscope TEM. Are measured and the average value thereof is taken as the average particle diameter.

Example 1
(Wavelength conversion layer)
A commercially available silicone elastomer (LR7665, manufactured by Asahi Kasei Wacker Silicone) was mixed with cerium activated YAG: Ce ³⁺ (average particle size 9 μm) so as to be 26% by weight. On top, it was coated to a thickness of 100 μm using an applicator and molded by heating at 100 ° C. for 5 minutes. The obtained molded body was cut into small pieces having a size of 8 mm × 8 mm (thickness: about 100 μm) using a die-molding apparatus to produce a wavelength conversion layer.

(Inorganic high thermal conductivity layer)
Polyvinyl alcohol as a binder resin is added to yttrium aluminate (YAG) (average particle diameter 9 μm) so that the weight of the inorganic material is 20% by weight, and an appropriate amount of isopropyl alcohol is added to form a slurry solution. Was prepared. Next, the obtained slurry-like solution was molded and then heated and sintered at 1000 ° C. for 5 hours so that the thickness after sintering was 500 μm, thereby preparing an inorganic high thermal conductive layer. The obtained inorganic high thermal conductive layer was sufficiently cooled and then cut into a size of 8 mm × 8 mm using a die-molding apparatus.

(Optical semiconductor device)
On the bottom of the concave mold (bottom 8 × 8 mm, height 1.1 mm), the wavelength conversion layer and the inorganic high thermal conductive layer obtained above were placed in this order, and as a sealing resin layer, a commercially available sealing resin layer was placed thereon. A silicone elastomer (LR7665) was mixed and mixed with 50% by weight of fused silica particles (FB-40S, manufactured by Denki Kagaku Kogyo Co., Ltd., average particle size: 40 μm). After that, the substrate on which the blue LED chip (1mm x 1mm x 0.17mm height) was mounted was placed so that the filled resin and the LED chip face each other, and then heated at 160 ° C for 5 minutes for sealing Process. Thereafter, the substrate was left until the shape did not change even at room temperature, and then the mold was removed to produce an optical semiconductor device.

Example 2
In Example 1, an optical semiconductor device was produced in the same manner as in Example 1 except that the inorganic high thermal conductive layer was changed to the one shown below.

(Inorganic high thermal conductivity layer)
Polyvinyl alcohol as a binder resin was added to glass (average particle size 5 μm) so that the weight of the inorganic material was 20% by weight, and an appropriate amount of isopropyl alcohol was added to prepare a slurry solution. Next, the obtained slurry-like solution was molded and then heated and sintered at 800 ° C. for 5 hours so that the thickness after sintering was 35 μm, thereby preparing an inorganic high thermal conductive layer. The obtained inorganic high thermal conductive layer was sufficiently cooled and then cut into a size of 8 mm × 8 mm using a die-molding apparatus.

Example 3
In Example 1, an optical semiconductor device was produced in the same manner as in Example 1 except that the fused silica particles were not blended in the sealing resin layer.

Example 4
In Example 2, an optical semiconductor device was produced in the same manner as in Example 2 except that no fused silica particles were blended in the sealing resin layer.

Example 5
In Example 1, an optical semiconductor device was produced in the same manner as in Example 1 except that the thickness of the inorganic high thermal conductive layer was changed from 500 μm to 300 μm.

Comparative Example 1
In Example 1, an optical semiconductor device was produced in the same manner as in Example 1 except that the inorganic high thermal conductive layer was not used.

Comparative Example 2
In Example 1, an optical semiconductor device was fabricated in the same manner as in Example 1 except that the inorganic high thermal conductive layer was used instead of the low thermal conductive layer shown below.

(Inorganic low thermal conductive layer)
A commercially available silicone elastomer (LR7665) was coated on a PET film (thickness 50 μm) using an applicator to a thickness of 100 μm and heated by heating at 150 ° C. for 5 minutes. It was cut into a small piece of 8 mm × 8 mm size (thickness: about 100 μm) to form an inorganic low thermal conductive layer.

Reference example 1
In Example 1, an optical semiconductor device (an optical semiconductor device having only a sealing resin layer) was produced in the same manner as in Example 1 except that the inorganic high thermal conductive layer and the wavelength conversion layer were not used.

  About the obtained semiconductor device, the characteristic was evaluated according to the following test examples 1-3. The results are shown in Tables 1-2.

Test example 1 (maximum temperature)
The maximum temperature of the optical semiconductor device at an input current of 1 A was measured using a non-contact radiation thermometer (manufactured by Chino Corporation).

Test example 2 (stimulus value Y, xy chromaticity)
Using an instantaneous multi-photometry system (MCPD-3000, manufactured by Otsuka Electronics Co., Ltd.), the stimulus value Y of the optical semiconductor device at an input current of 1 A and the xy chromaticity diagram (CIE1931) in the XYZ color system were measured. The stimulus value Y is an index of the luminance of the optical semiconductor device, and indicates that when the input current 1A is 18000 or more, the luminance is excellent.

Test Example 3 (Light transmittance)
The light transmittance was evaluated by measuring the light transmittance for a wavelength of 560 nm using an ultraviolet-visible spectrum measuring instrument (U4100, manufactured by Hitachi).

  As a result, the optical semiconductor device of the example has a significantly lower maximum temperature at the time of 1A input than the optical semiconductor device of Comparative Example 1 in which no high thermal conductive layer is installed or Comparative Example 2 having a low thermal conductive layer. It was a thing. From this, it can be seen that the heat generated in the wavelength conversion layer is radiated by heat conduction to the high thermal conduction layer. In addition, since Example 1 and Reference Example 1 have almost the same maximum temperature when 1A is charged, in the apparatus of Example 1, almost all of the heat generated in the wavelength conversion layer is conducted and dissipated. It is suggested. Furthermore, in the optical semiconductor devices of Examples 1 to 5, since the heat conductive layer is transparent, no decrease in chromaticity or luminance is recognized.

In addition, the following are mentioned as an aspect of this invention.
[1] An optical semiconductor device comprising a substrate on which an LED chip is mounted, a sealing resin layer in which the LED chip is embedded, an inorganic high thermal conductive layer, and a wavelength conversion layer containing inorganic phosphor powder. An optical semiconductor device in which a sealing resin layer, an inorganic high thermal conductive layer, and a wavelength conversion layer are directly or indirectly laminated in this order on the substrate.
[2] The optical semiconductor device according to [1], wherein the inorganic high thermal conductive layer is a layer made of yttrium aluminate (YAG).
[3] The optical semiconductor device according to [2], wherein the inorganic high thermal conductive layer is a layer made of glass.
[4] The optical semiconductor device according to any one of [1] to [3], wherein the sealing resin layer contains silica fine particles.
[5] The optical semiconductor device according to any one of [1] to [4], wherein the inorganic high thermal conductive layer has a thermal conductivity of 1.0 W / mK or more.
[6] A wavelength conversion layer and an inorganic high thermal conductive layer are formed in this order in a concave mold, and a sealing resin is filled on the inorganic high thermal conductive layer, and then a substrate on which an LED chip is mounted is the sealing resin. A method for manufacturing an optical semiconductor device, wherein the method is embedded and sealed.

  The optical semiconductor device of the present invention is suitably used for high power applications such as general lighting fixtures using LEDs as light sources, display backlights, automobile headlights, and the like.

DESCRIPTION OF SYMBOLS 1 Board | substrate with which LED chip was mounted 2 Sealing resin layer 3 which can embed LED chip Inorganic high thermal conductive layer 4 Wavelength conversion layer 5 containing inorganic fluorescent substance powder Recessed mold

Claims (6)

  An optical semiconductor device comprising a flat substrate on which an LED chip is mounted, a sealing resin layer in which the LED chip is embedded, an inorganic high thermal conductive layer, and a wavelength conversion layer containing inorganic phosphor powder. The sealing resin layer, the inorganic high thermal conductive layer, and the wavelength conversion layer are directly or indirectly laminated in this order on the substrate, and the thickness of the inorganic high thermal conductive layer is 10 to 1000 μm. An optical semiconductor device.   The optical semiconductor device according to claim 1, wherein the inorganic high thermal conductive layer is a layer made of yttrium aluminate (YAG).   The optical semiconductor device according to claim 1, wherein the inorganic high thermal conductive layer is a layer made of glass.   The optical semiconductor device according to claim 1, wherein the sealing resin layer contains silica fine particles.   The optical semiconductor device according to any one of claims 1 to 4, wherein the inorganic high thermal conductive layer has a thermal conductivity of 1.0 W / mK or more.   The optical semiconductor device according to any one of claims 1 to 5, wherein the sealing resin layer, the inorganic high thermal conductive layer, and the wavelength conversion layer have the same area.