JP2010186952A - Semiconductor light emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor light emitting device maintaining an excellent optical characteristic and securing high reliability regardless of bright and long-term use and a use environment condition. <P>SOLUTION: In this semiconductor light emitting device, a light reflecting layer 6 made of a silver-based material and having high reflectivity is formed on a base material 2; a transparent silica glass film 7 is formed on the light reflecting layer 6; and a semiconductor light emitting element 9 having translucency is stuck and fixed to the silica glass film 7 through a silicone adhesive 8. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a semiconductor light emitting device using a semiconductor light emitting element as a light source.

  The light emission spectrum of a semiconductor light emitting element differs depending on the element constituting the semiconductor material and its composition, the element structure of the semiconductor material, and the like, and the semiconductor material has different light transmittance depending on the element constituting the semiconductor material and the composition thereof.

  When the semiconductor light-emitting element has a light-transmitting element structure, light emitted from the light-emitting portion (PN junction portion) in the semiconductor light-emitting element is guided from both sides facing the light-emitting portion while being guided through the element. It is emitted outside.

  By the way, a semiconductor light emitting element is generally fixed on a base material on which a conductor pattern is formed via an adhesive member or a bonding member, and the element electrode of the semiconductor light emitting element and the conductor pattern are electrically connected by some connecting means. The As a result, electric power from the external power source is supplied to the semiconductor light emitting element via the conductor pattern and the element electrode.

  Therefore, when the semiconductor light-emitting element having translucency is mounted on the base material by the above-described method and electric power is supplied from the external power source, the surface located on the base-side of the light emitted from the light-emitting portion of the semiconductor light-emitting element The light emitted from the light is shielded by the adhesive member or the joining member and is not irradiated outside the element, but is irradiated toward the outside of the element only from one surface. Therefore, almost half of the amount of light emitted from the light emitting unit is not irradiated outside the element, resulting in extremely low light utilization efficiency.

  Therefore, for the purpose of improving the utilization efficiency of the light emitted from the semiconductor light emitting element, a semiconductor light emitting device having the configuration shown in FIG. 5 has been proposed.

  The light reflecting layer 52 made of a material having a light reflectance higher than that of the base material 50 is provided on the conductive pattern 51 on the base material 50, and the light transmitting layer 52 is made transparent through a transparent adhesive 53. The semiconductor light emitting element 54 is adhered and fixed, and the semiconductor light emitting element 54 is sealed with a sealing resin 55.

Then, the semiconductor light L _D emitted toward the surface located on the opposite side of the substrate 50 from the light emitting portion (upper surface) of the light emitting element 54 is a semiconductor light emitting element is guided sealing resin 55 in the top surface 54 , Is guided through the sealing resin 55 and irradiated toward the outside.

On the other hand, the light L _R emitted from the light emitting unit toward the surface (lower surface) located on the substrate 50 side of the semiconductor light emitting element 54 is emitted from the lower surface is guided to the semiconductor light emitting element 54, a transparent adhesive 53, reaches the light reflecting layer 52, is reflected toward the semiconductor light emitting element 54 side by the light reflecting layer 52, is again guided in the semiconductor light emitting element 54, and enters the sealing resin 55 from the upper surface, The inside of the sealing resin 55 is guided and irradiated to the outside.

Thus, it is possible to irradiate the reflected light L _R reflected by the light reflecting layer 52 is emitted from the emitted light directly L _D and the light emitting portion from the light emitting portion of the semiconductor light emitting element 54 to the outside efficiently, light The use efficiency can be increased (see, for example, Patent Document 1).

JP 2007-31401 A

  By the way, in the semiconductor light emitting device 56 having the above configuration, the light reflecting layer 52 uses a silver plating layer in order to ensure high reflectance, and the adhesive 53 has good optical stability with respect to the light emitted from the semiconductor light emitting element 54. It is preferable to use the above silicone-based adhesive.

  However, when the inventor conducted a long-time lighting test using a blue LED element that emits blue light as the semiconductor light emitting element 54, it was confirmed that discoloration occurred in the silicone-based adhesive 53 and light absorption occurred. It was done. After the test, when the discolored silicone adhesive 53 was analyzed, a silver component was detected, and the silicone adhesive 53 contained more various additives such as an adhesion aid than the silicone resin for sealing. Because of this tendency, the cause of discoloration is presumed to be due to these additives.

  In addition, the silicone-based adhesive 53 has a relatively low adhesive strength to metal, and there is a possibility that interface peeling with the metal may occur due to thermal stress due to heat generated when the semiconductor light emitting element 54 is turned on.

  Accordingly, the present invention was devised in view of the above problems, and an object of the present invention is to provide a semiconductor light-emitting element having translucency in which the peak wavelength of the emission spectrum is a short wavelength region of ultraviolet to visible. It is a semiconductor light emitting device with high light utilization efficiency, which is bonded and fixed on a silver-based layer with high light reflectivity through a silicone-based adhesive having good optical stability with respect to light in the short wavelength region, An object of the present invention is to realize a semiconductor light-emitting device that is bright and capable of maintaining good optical characteristics and ensuring high reliability regardless of long-term use and use environment conditions.

In order to solve the above problems, the invention described in claim 1 of the present invention is:
A substrate;
A light reflecting layer made of a silver-based material formed on the substrate;
A silica glass film formed on the light reflecting layer so as to cover the light reflecting layer;
A semiconductor light-emitting element that is fixed to the silica glass layer via a silicone adhesive, has a light-transmitting property, and has a peak wavelength of an emission spectrum in a short wavelength region from ultraviolet to visible,
It is characterized by comprising.

In addition, the invention described in claim 2 of the present invention is as follows.
A conductor pattern is provided with a step with respect to a surface of the substrate that contacts the light reflecting layer, and the element electrode of the semiconductor light emitting element and the conductor pattern are electrically connected via a bonding wire. It is what.

In addition, the invention described in claim 3 of the present invention is as follows.
The substrate includes a recess having an opening on one surface and a conductor pattern formed on the one surface, and the light reflecting layer and the silica glass film are formed on at least the bottom surface of the inner surface of the recess, and the semiconductor light emitting element is It is located in the said recessed part, The element electrode of the said semiconductor light-emitting device and the said conductor pattern are electrically connected through the bonding wire, It is characterized by the above-mentioned.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the semiconductor light emitting element is a blue LED element that emits blue light or an ultraviolet LED element that emits ultraviolet light. In addition, the semiconductor light emitting element is sealed with a sealing resin containing at least one phosphor so as to cover the semiconductor light emitting element.

  In the structure of the semiconductor light emitting device of the present invention, a light reflecting layer made of a silver-based material having a high reflectance is formed on a base material, and a transparent silica glass film is formed on the light reflecting layer. A translucent semiconductor light emitting device is bonded and fixed to the glass film via a transparent silicone adhesive.

  With such a configuration of the semiconductor light emitting device, the use efficiency of the light emitted from the semiconductor light emitting element is increased, the discoloration of the silicone adhesive due to the light emitted from the semiconductor light emitting element is prevented, and the adhesive strength of the semiconductor light emitting element Improved.

  As a result, a semiconductor light emitting device capable of maintaining good optical characteristics and ensuring high reliability regardless of whether it is bright and used for a long period of time or in the environment of use has been realized.

It is a top view concerning the embodiment of the present invention. It is AA sectional drawing of FIG. FIG. 2 is a partial view of FIG. 1. It is explanatory drawing which concerns on other embodiment of this invention. It is explanatory drawing of a prior art example.

  Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to FIGS. 1 to 4 (the same reference numerals are given to the same parts). The embodiments described below are preferable specific examples of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention particularly limits the present invention in the following description. Unless stated to the effect, the present invention is not limited to these embodiments.

  1 and 2 are explanatory views of an embodiment according to a semiconductor light emitting device of the present invention. FIG. 1 is a top view and FIG. 2 is a cross-sectional view taken along line AA of FIG.

  The present invention uses a light-emitting source as a semiconductor light-emitting element (hereinafter referred to as “LED element”) having a light-transmitting peak wavelength in the ultraviolet to visible short wavelength region, and emits the LED element from the LED element. Adhered to silica glass film formed on silver layer with high light reflectivity through silicone adhesive with good optical stability and transparency to ultraviolet to visible short wavelength region light This is a fixed semiconductor light emitting device.

  With such a configuration of the semiconductor light emitting device, the light use efficiency is improved, the amount of irradiation light is increased, and good optical characteristics are maintained and high reliability is ensured regardless of long-term use and use environment conditions. Is possible.

  A specific configuration example will be described below. A housing 4 having a hollow portion 3 larger than the concave portion 1 is disposed on an upper portion of the base material 2 having the concave portion 1. On both sides of the base material 2 facing each other with the concave portion 1 interposed therebetween, the other side is separated and independent from one surface (upper surface) 2a of the base material 2 through the housing 4 and led out to the outside through the side surface 2b. Conductive patterns 5a and 5b extending to the surface (back surface) 2c are formed.

  The tip portions of the conductor patterns 5a and 5b located on the upper surface 2a of the substrate 2 are exposed in the hollow portion 3 of the housing 4 and become wire bonding pad portions 5aa and 5ba of bonding wires to be described later. Each of the conductor patterns 5a and 5b has a laminated structure in which, for example, a nickel (Ni) plating layer is formed on a copper (Cu) foil and a gold (Au) plating layer is further formed thereon.

  A light reflecting layer 6 is formed on the inner surface of the concave portion 1 of the substrate 2 so as to be separated and independent from the conductor patterns 5a and 5b. The light reflecting layer 6 is a silver-based material having a high light reflectance such as pure silver or a silver alloy. It is made up of. A transparent silica glass film 7 is formed on the light reflecting layer 6.

This silica glass film 7 is obtained by applying perhydropolysilazane ((SiH ₂ NH) _n ) diluted with dibutyl ether on the light reflection layer 6 and heating it at 150 ° C. for 1 hour to cause chemical reaction with moisture in the atmosphere. Thus, the silica glass film 7 is obtained by dislocation to silica (silicon dioxide).

  At this time, it is preferable to optimize the concentration of perhydropolysilazane and the coating thickness so that the silica glass film 7 has a thickness of 1 μm or less in order to prevent cracking due to thermal stress and peeling from the light reflecting layer 6.

  If the silica glass film 7 adheres to the wire bonding pad portions 5aa and 5ba of the conductor patterns 5a and 5b when the silica glass film 7 is formed, the bonding strength of the bonding wire may be weakened or the bonding itself may not be performed.

  Therefore, as a countermeasure for preventing the silica glass film 7 from adhering to the wire bonding pad portions 5aa and 5ba of the conductor patterns 5a and 5b, consideration is given to the formation process of the silica glass film 7 or the structure of the semiconductor light emitting device. It is possible. Specifically, a method of forming a silica glass film 7 before the formation of the conductor patterns 5a and 5b on the base material 2 so that the silica glass film 7 does not adhere to the conductor patterns 5a and 5b in the process, or As shown in FIG. 1 and FIG. 2, a step is provided in the wire bonding pad portions 5 aa and 5 ba of the conductor patterns 5 a and 5 b and the silica glass film 7 to manufacture the silica glass film 7. A method of making the structure difficult to adhere to the wire bonding pad portions 5aa and 5ba of 5a and 5b is preferable as a countermeasure.

  An LED element 9 is bonded and fixed on the silica glass film 7 via a silicone adhesive 8. Since the silicone adhesive 8 has better adhesion to glass than metal, the adhesion / fixation of the LED element 9 via the silicone adhesive 8 is to the silica glass film 7 rather than to the light reflecting layer 6 made of a silver-based material. The higher adhesive strength can be ensured.

  Further, the silica glass film 7 plays a role of preventing sulfidation of the silver-based material constituting the light reflecting layer 6. Therefore, it is preferable to achieve a good antisulfurization effect by covering the entire surface of the light reflecting layer 6 with the silica glass film 7.

The silica glass film 7 can be formed by various methods such as sputtering using SiO ₂ as a target material in addition to the method using perhydropolysilazane.

  The LED element 9 is a light-transmitting element whose emission spectrum has a peak wavelength in the ultraviolet to visible short wavelength region, and is composed of, for example, InGaAl, InGaAlN, InGaN, and GaN-based composition materials, all of which have high light transmittance. Have a rate.

  In addition, a pair of electrodes (not shown, an anode electrode and a cathode electrode) of the LED element 9 are both provided on one surface side (upper surface side) of the element, and one end of the bonding wire 10 is joined to each other. The other end of the bonding wire 10 is bonded to the wire bonding pad portions 5aa and 5ba of the conductor patterns 5a and 5b. Thereby, each electrode of the LED element 9 and the conductor patterns 5 a and 5 b are electrically connected via the bonding wires 10.

  Further, the recessed portion 1 of the base material 2 and the hollow portion 3 of the housing 4 which are continuously drilled are filled with a sealing resin 11 to seal the LED element 9 and the bonding wire 10 with resin.

  As the sealing resin 11, a translucent resin or a translucent resin obtained by dispersing one or more phosphors is used. Among these, when only the translucent resin is used as the sealing resin 11, the LED element 9 is mainly used in which the peak wavelength of the emission spectrum is in the visible region.

  On the other hand, when 1 or more types of fluorescent substance are disperse | distributed and used for translucent resin used as binder resin as the sealing resin 11, the combination of the LED element 9 and the sealing resin 11 is as follows.

  For example, in the case of a blue LED element in which the emitted light of the LED element 9 has a peak wavelength of the emission spectrum in the blue region of the visible short wavelength region, it is excited by the blue light emitted from the blue LED element and becomes yellow light that becomes a complementary color of blue By using the yellow phosphor for wavelength conversion, a part of the blue light emitted from the blue LED element is converted into the wavelength of the yellow light excited by exciting the yellow phosphor and the blue light emitted from the blue LED element. White light can be obtained by additive color mixing with a part.

  Similarly, when the LED element 9 is a blue LED element, a mixture of two types of phosphors, a green phosphor and a red phosphor, which are excited by the blue light emitted from the blue LED element and convert the wavelength into green light and red light, respectively. By using the phosphor, a part of the blue light emitted from the blue LED element excites the mixed phosphor to convert the green light and red light, and one of the blue light emitted from the blue LED element. White light can be obtained by additive color mixing with the part.

  Further, in the case of an ultraviolet LED element in which the emitted light of the LED element 9 has a peak wavelength of the emission spectrum in the ultraviolet region, the blue light that is excited by the ultraviolet light emitted by the ultraviolet LED element and converts into wavelengths of blue light, green light, and red light, respectively. By using a mixed phosphor composed of three types of phosphors, a phosphor, a green phosphor and a red phosphor, ultraviolet light emitted from an ultraviolet LED element is wavelength-converted by exciting the mixed phosphor. White light can be obtained by additive color mixture of green light and red light.

  Furthermore, light of various color tones other than white light can be obtained by appropriately combining light of various color tones emitted from the LED element and a phosphor that is excited by the light and converts the wavelength to various wavelengths.

  Therefore, in the semiconductor light emitting device 20 having the above-described configuration, the optical path of the light emitted from the LED element 9 will be described with reference to FIG.

Light L _D emitted toward the position plane (upper surface) 9b on the opposite side from the light emitting portion (PN junction) 9a and base 2 of the LED element 9, the electrically the LED element 9 having translucency The light is incident on the sealing resin 11 from the upper surface 9b, guided through the sealing resin 11, and irradiated outward.

On the other hand, the light L _R from the light emitting portion 9a emitted toward the surface (lower surface) 9c located on the substrate 2 side of the LED element 9 emits the LED element 9 from the light that is led by the lower surface 9c toward the lower surface 9c Then, the transparent silicone adhesive 8 and the transparent silica glass film 7 are sequentially transmitted to the light reflecting layer 6 made of a silver material and having a high light reflectance, and the light reflecting layer 6 faces the LED element 9 side. Reflected efficiently, the silica glass film 7 and the silicone adhesive 8 are sequentially transmitted again, guided through the LED element 9, and incident on the sealing resin 11 from the upper surface 9b through the light emitting portion 9a. The light is guided inside and irradiated toward the outside.

Thus, it is possible to irradiate the reflected light L _R reflected is emitted from the emitted light directly L _D and the light emitting portion 9a from the light emitting portion 9a by the light reflecting layer 6 of the LED element 9 to the outside efficiently, The utilization efficiency of light is increased, and the bright semiconductor light emitting device 20 can be realized by increasing the amount of irradiation light. Further, the presence of the silica glass film 7 between the light reflecting layer 6 containing the silver-based material and the silicone adhesive 8 suppresses discoloration due to photodegradation of the silicone adhesive 8 although the cause is unknown. The lifetime of 20 can be improved. Note that when a phosphor in the sealing resin 11 is dispersed, includes direct light L _D and the fluorescent light by the excited fluorescent material in the light emitted from the LED element 9 in the reflected light L _R .

  FIG. 4 is an explanatory diagram of another embodiment according to the semiconductor light emitting device 20 of the present invention. In the present embodiment, the above-described embodiment is provided with a recess in the substrate and the LED element is disposed in the recess, whereas the substrate 2 is not provided with a recess and the wire bonding pad portion of the conductor patterns 5a and 5b. 5aa, 5ba and the light reflecting layer 6 are formed on the same plane of the substrate 2, and the LED element 9 is bonded to the silica glass film 7 formed on the light reflecting layer 6 through the transparent silicone adhesive 8. -The difference is that it has a fixed configuration.

  In the semiconductor light emitting device 20 having such a configuration, as a countermeasure for preventing the silica glass film 7 from adhering to the wire bonding pad portions 5aa and 5ba of the conductor patterns 5a and 5b, the conductor patterns 5a and 5b with respect to the substrate 2 are used. It is preferable to take a method of providing a forming step of the silica glass film 7 before the forming step.

  Note that the optical system of this embodiment is the same as that of the above-described embodiment, and thus the description thereof is omitted.

  As described above, in the semiconductor light emitting device of the present invention, a light reflecting layer made of a silver-based material having a high reflectance is formed on a base material, and a transparent silica glass film is formed on the light reflecting layer. Then, a translucent semiconductor light emitting device is bonded and fixed to the silica glass film through a transparent silicone adhesive.

  As a result, light emitted from the light emitting part in the semiconductor light emitting element toward both sides of the light emitting part has little light loss until it is emitted to the outside of the semiconductor light emitting element. It has become possible to realize a semiconductor light emitting device with a bright increase in light quantity.

  Further, by separating the light reflecting layer and the silicone adhesive by interposing a silica glass film between the light reflecting layer and the silicone adhesive, the silver-based material constituting the light reflecting layer and the additive of the silicone adhesive It became possible to prevent discoloration of the silicone adhesive considered to be caused by the reaction, and it was possible to maintain good optical properties regardless of long-term use.

  Furthermore, since the semiconductor light emitting element is bonded and fixed to a silica glass film having a stronger adhesive strength than the light reflecting layer made of a silver-based material via a silicone adhesive, the die shear strength of the semiconductor light emitting element is bonded to the light reflecting layer. It is about 1.5 times higher than when fixed, and high reliability can be secured regardless of the environmental conditions of use.

  In other words, the semiconductor light-emitting device of the present invention is bright and can maintain good optical characteristics and ensure high reliability irrespective of long-term use and use environment conditions.

DESCRIPTION OF SYMBOLS 1 Recessed part 2 Base material 2a Upper surface 2b Side surface 2c Back surface 3 Hollow part 4 Housing 5a, 5b Conductive pattern 5aa, 5ba Wire bonding pad part 6 Light reflection layer 7 Silica glass film 8 Silicone adhesive 9 Semiconductor light emitting element (LED element)
9a Light emitting portion 9b Upper surface 9c Lower surface 10 Bonding wire 11 Sealing resin 20 Semiconductor light emitting device

Claims (4)

A substrate;
A light reflecting layer made of a silver-based material formed on the substrate;
A silica glass film formed on the light reflecting layer so as to cover the light reflecting layer;
A semiconductor light-emitting element that is fixed to the silica glass layer via a silicone adhesive, has a light-transmitting property, and has a peak wavelength of an emission spectrum in a short wavelength region from ultraviolet to visible,
A semiconductor light emitting device comprising:   A conductor pattern is provided with a step with respect to a surface of the substrate that contacts the light reflecting layer, and the element electrode of the semiconductor light emitting element and the conductor pattern are electrically connected via a bonding wire. The semiconductor light emitting device according to claim 1.   The substrate includes a recess having an opening on one surface and a conductor pattern formed on the one surface, and the light reflecting layer and the silica glass film are formed on at least the bottom surface of the inner surface of the recess, and the semiconductor light emitting element is 2. The semiconductor light emitting device according to claim 1, wherein the semiconductor light emitting device is located in the recess, and the element electrode of the semiconductor light emitting element and the conductor pattern are electrically connected via a bonding wire.   The semiconductor light emitting element is a blue LED element that emits blue light or an ultraviolet LED element that emits ultraviolet light, and the semiconductor light emitting element contains one or more phosphors so as to cover the semiconductor light emitting element. The semiconductor light-emitting device according to claim 1, wherein the semiconductor light-emitting device is sealed with a sealing resin.

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