JP2012156384A - Optical device, light-emitting device, and method for producing functionally gradient material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a functionally gradient material which prevents a metal electrode from corroding and improves light resistance, and to provide a light-emitting device using the functionally gradient material.SOLUTION: A functionally gradient material comprises: an electrode corrosion inhibitor containing a siloxane compound comprising tetraalkoxysilane, methyltrialkoxysilane, (3-mercapto propyl)trialkoxysilane on one side thereof; and a sealing material containing a polysiloxane compound comprising tetraalkoxysilane, methyltrialkoxysilane, dialkoxydimethylsilane on the other side thereof. A composition ratio of the siloxane compound and the polysiloxane compound changes gradually from one side toward the other side. A light-emitting device using the functionally gradient material is also provided.

Description

  The present invention relates to a substrate on which an optical semiconductor element such as an LED (Light Emitting Diode) is mounted, and a light emitting device that seals the optical semiconductor element with a functionally gradient material.

  An LED lamp known as an optical semiconductor device has a light emitting diode (LED) as an optical semiconductor element, and has an LED mounted on a substrate sealed with a sealing agent made of a transparent resin. As a sealant for sealing the LED, an epoxy resin-based composition has been widely used conventionally (see, for example, Patent Document 1).

  However, epoxy resin-based sealants are prone to cracking and yellowing due to increased heat generation and shorter wavelength of light due to recent miniaturization of semiconductor packages and higher brightness of LEDs, resulting in lower reliability. Was invited.

  Then, the silicone composition is used as a sealing agent from the point which has the outstanding heat resistance. In particular, an addition reaction curable silicone composition cures in a short time by heating, and thus has high productivity and is suitable as an LED sealant (see, for example, Patent Document 2).

JP 2000-198930 A JP 2004-292714 A

  However, since the silicone composition is generally excellent in gas permeability, it is easily affected by the external environment. When the LED lamp is exposed to sulfur compounds or exhaust gas in the atmosphere, the sulfur compounds pass through the cured product of the silicone composition, and the metal electrode on the substrate sealed with the cured product, particularly the Ag electrode Corrodes over time and turns black.

  An object of the present invention is to address such problems, and is to provide a functionally gradient material that prevents corrosion of a metal electrode and a light-emitting device formed using the functionally gradient material.

The present invention provides the following means in order to solve the above problems.
The optical device according to the present invention is an optical device having a metal electrode, wherein the metal electrode is a siloxane composed of tetraalkoxysilane, methyltrialkoxysilane, (3-mercaptopropyl) trialkoxysilane on the surface side in contact with the metal electrode It has an electrode corrosion inhibitor containing a compound, and has a sealing material containing a polysiloxane compound composed of tetraalkoxysilane, methyltrialkoxysilane, dialkoxydimethylsilane on the surface opposite to the surface in contact with the metal electrode, A sealing formed of a functionally graded material, wherein the composition ratio of the siloxane compound and the polysiloxane compound changes in a slanting manner from the surface side in contact with the metal electrode toward the opposite surface side It is characterized by being covered with a layer.

  Thereby, while improving the corrosion resistance of the electrode of an optical device, the light resistance of an optical device can be improved.

  The siloxane compound is a compound obtained by mixing tetraethoxysilane: methyltriethoxysilane: (3-mercaptopropyl) triethoxysilane in a molar ratio of 30-60: 30-60: 1, and the polysiloxane compound is It is a compound in which diethoxydimethylsilane: tetraethoxysilane: methyltriethoxysilane is mixed at a molar ratio of 78 to 156: 1: 1.

  The light emitting device according to the present invention includes a substrate, an optical semiconductor element mounted on the substrate, a metal electrode formed on the substrate and electrically connected to the optical semiconductor element, the optical semiconductor element, A sealing layer that covers the metal electrode, wherein the sealing layer has a tetraalkoxysilane, methyltrialkoxysilane, (3-mercaptopropyl) trialkoxysilane on a surface side in contact with the metal electrode. An encapsulant containing a polysiloxane compound comprising tetraalkoxysilane, methyltrialkoxysilane, dialkoxydimethylsilane on the side opposite to the surface in contact with the metal electrode. And the siloxane compound and the polymer from the surface side in contact with the metal electrode toward the opposite surface side. Wherein the composition ratio of the siloxane compound is formed by FGM materials is changing inclinatorily.

  Thereby, while improving the corrosion resistance of electrodes, such as a light emitting device, the light resistance of a light emitting device can be improved reliably. Moreover, since the electrode corrosion inhibitor and the sealing material are integrated as a functionally gradient material, adhesion can be improved.

  The siloxane compound is a compound obtained by mixing tetraethoxysilane: methyltriethoxysilane: (3-mercaptopropyl) triethoxysilane in a molar ratio of 30-60: 30-60: 1, and the polysiloxane compound is It is a compound in which diethoxydimethylsilane: tetraethoxysilane: methyltriethoxysilane is mixed at a molar ratio of 78 to 156: 1: 1.

Moreover, the manufacturing method of the functionally gradient material according to the present invention is an electrode in which an electrode corrosion inhibitor containing a siloxane compound composed of tetraalkoxysilane, methyltrialkoxysilane, and (3-mercaptopropyl) trialkoxysilane is applied on a metal electrode. A corrosion inhibitor coating step, a sealing material coating step of coating a sealing material containing a polysiloxane compound comprising tetraalkoxysilane, methyltrialkoxysilane, dialkoxydimethylsilane on the electrode corrosion inhibitor; and the electrode corrosion And a curing step of simultaneously curing the inhibitor and the sealing material.
Thereby, the functional gradient material by an electrode corrosion inhibitor and a sealing material can be formed.

Moreover, in the said hardening process, a microwave is irradiated, It is characterized by the above-mentioned.
Thereby, hardening time can be shortened and the formation process time of a functionally gradient material can be shortened.

In the electrode corrosion inhibitor coating step, the electrode corrosion inhibitor is applied in a thickness of 0.5 to 6 μm.
Thereby, generation | occurrence | production of a crack etc. can be prevented, maintaining corrosion resistance.

  With the configuration described above, corrosion of the electrode of the optical device including the electrode can be prevented. Furthermore, in the light emitting device, a highly reliable light emitting device having light resistance and corrosion resistance can be provided.

It is a schematic sectional drawing for showing the process of forming one Embodiment of the light emitting device of this invention. It is a schematic sectional drawing for showing the process of forming one Embodiment of the light emitting device of this invention. It is a schematic sectional drawing for showing the process of forming one Embodiment of the light emitting device of this invention. It is a schematic sectional drawing which shows one Embodiment of the light-emitting device of this invention. It is a schematic sectional drawing for showing the process of forming one Embodiment of the light emitting device of this invention. It is a schematic sectional drawing which shows one Embodiment of the light-emitting device of this invention. It is a schematic sectional drawing for showing the process of forming one Embodiment of the light emitting device of this invention. It is a schematic sectional drawing which shows one Embodiment of the light-emitting device of this invention. It is sectional observation drawing of the light-emitting device of this invention. It is a cross-sectional observation figure of the light emitting device for a comparison.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
1 to 3 are schematic cross-sectional views for illustrating a process of forming an embodiment of the light-emitting device of the present invention, and FIG. 4 is a schematic cross-sectional view illustrating an embodiment of the light-emitting device of the present invention.

  As shown in FIG. 4, the light emitting device 1 of the present embodiment includes a substrate 3, an optical semiconductor element 6 mounted on the substrate, and a metal electrode formed on the substrate 3 and electrically connected to the optical semiconductor element 6. 4 and 5 and a sealing layer 9 formed of a functionally gradient material that covers the metal electrodes 4 and 5.

  The sealing layer 9 has an electrode corrosion prevention layer containing a siloxane compound composed of tetraalkoxysilane, methyltrialkoxysilane, and (3-mercaptopropyl) trialkoxysilane on the surface side in contact with the metal electrodes 4 and 5. 4 and 5 have a sealing material containing a polysiloxane compound composed of tetraalkoxysilane, methyltrialkoxysilane, dialkoxydimethylsilane on the side opposite to the side in contact with 4, 5 and opposite from the side in contact with metal electrodes 4 and 5 The composition ratio of the siloxane compound and the polysiloxane compound is formed with a functionally graded material that changes in a slope toward the surface side.

  That is, the functionally gradient material of the present embodiment has an electrode corrosion inhibitor containing a siloxane compound composed of tetraalkoxysilane, methyltrialkoxysilane, and (3-mercaptopropyl) trialkoxysilane on one side, The surface side has a sealing material containing a polysiloxane compound composed of tetraalkoxysilane, methyltrialkoxysilane, dialkoxydimethylsilane, and the siloxane compound and the polysiloxane compound from one surface side to the other surface side And the composition ratio changes in a slanting manner.

  The functionally graded layer 9 may further contain a curing agent or a curing catalyst. Thereby, it can be hardened reliably.

Hereinafter, the manufacturing method of the light-emitting device of this embodiment will be described with reference to FIGS.
FIG. 1 is a diagram illustrating a process of forming a metal electrode on a substrate (metal electrode formation process) and a process of installing a reflective member (reflective member installation process).

  In the metal electrode forming step, metal electrodes 4 and 5 made of silver wiring electrodes or the like formed on the substrate 3 using a silver paste or the like are formed.

  Further, in the reflection member installation step, the reflection member 2 in which the inclined through hole is formed is installed on the substrate 3 via the metal electrodes 4 and 5.

  As a material for the substrate 3, ceramics is generally used. In addition, the material of the board | substrate 3 can be used if it is resin although it can endure the temperature heated when forming the metal electrodes 4 and 5, For example, a polyimide resin etc. can be used.

  The reflecting member 2 has an inclined through hole that narrows from the opening end toward the bottom surface. Further, the inclined through hole is formed, for example, in a circular shape in a top view of the light emitting device 1.

  As the material of the reflecting member 2, ceramics such as porous ceramics are generally used. Further, the reflection member 2 and the substrate are bonded using the epoxy resin or the like to the substrate 3 on which the metal electrodes 4 and 5 are formed.

  FIG. 2 is a diagram showing a process of mounting the optical semiconductor element 6 on the substrate 3 (optical semiconductor element mounting process).

  In the optical semiconductor element mounting step, the optical semiconductor element 6 is mounted on the substrate by being mounted on the metal electrode 4. The optical semiconductor element 6 is electrically connected to the metal electrode 5 by a wire bond 7.

  Although not shown, the optical semiconductor element 6 and the metal electrode 4 are joined using a silver paste, a tin-silver paste, a paste containing silver nanoparticles, or the like. Further, the connection between the optical semiconductor element 6 and the metal electrode 4 is not limited to the paste agent, and solder or the like may be used.

  FIG. 3 is a diagram showing a step of applying an electrode corrosion inhibitor 8 that covers the metal electrodes 4 and 5 (electrode corrosion inhibitor application step).

  The electrode corrosion inhibitor 8 contains a siloxane compound composed of tetraalkoxysilane, methyltrialkoxysilane, and (3-mercaptopropyl) trialkoxysilane. Moreover, you may contain these hydrolysates and the siloxane bond compound which these couple | bonded. The electrode corrosion inhibitor 8 is a material on the metal electrode 4 side of the functionally gradient material described later.

  In this embodiment, a mixture is used with tetraethoxysilane: methyltriethoxysilane: (3-mercaptopropyl) triethoxysilane: water: acetic acid = 50: 50: 1: 175: 5 (molar ratio). The mixture stirred at 80 ° C. for 20 minutes is allowed to cool to room temperature. Then, it is diluted 5 times with a solvent of ethanol and hexane in a volume ratio of 1: 2. Thereafter, the metal electrode 4 is applied by a spray method, a dip method, a brush application method, or the like. Thereafter, the mixture is heated at 80 ° C. for 5 minutes to remove the solvent.

  The thickness of the electrode corrosion inhibitor 8 is 0.5 to 6 μm. The thickness of the electrode corrosion inhibitor 8 is preferably 1 to 2 μm. When the layer of the electrode corrosion inhibitor 8 is thinner than 0.5 μm, the corrosion resistance cannot be ensured. In addition, the thicker the electrode corrosion inhibitor 8 is, the better the corrosion resistance is. However, when the electrode corrosion inhibitor 8 is several tens of μm thick, it cracks when dried or when the sealing layer 9 is cured. Occurs and corrosion occurs from the crack. For this reason, the thickness of the electrode corrosion inhibitor layer is preferably 6 μm or less.

  In addition, said mixing ratio is an example, for example, when the molar ratio of (3-mercaptopropyl) triethoxysilane is 1, the molar ratio of tetraethoxysilane is 30 to 60, and the molar ratio of methyltriethoxysilane is 30-60 may be sufficient. Moreover, the molar ratio of water may be 175 to 350, and the molar ratio of acetic acid may be 2 to 10. Water may be added as appropriate after heating.

  FIG. 4 is a diagram showing a step (gradient function material forming step) in which a sealing material is applied on the electrode corrosion inhibitor 8 and the optical semiconductor element 6 (sealing material application step) to form a functionally gradient material.

  The sealing material contains a polysiloxane compound composed of tetraalkoxysilane, methyltrialkoxysilane, dialkoxydimethylsilane. Moreover, you may contain these hydrolysates and the siloxane bond compound which these couple | bonded.

  In this embodiment, the functionally gradient material is formed of a mixture of diethoxydimethylsilane: tetraethoxysilane: methyltriethoxysilane: water: acetic acid = 78: 1: 1: 1230: 8 (molar ratio). The mixture is stirred at 80 ° C. for 22 hours, and further stirred at 150 ° C. for 6 hours. Thereafter, a curing catalyst is dropped and heated at 150 ° C. for 2 hours. At this time, the electrode corrosion inhibitor 8 is solidified simultaneously.

  Since the functionally gradient material is solidified simultaneously with the electrode corrosion inhibitor 8, the interface between the electrode corrosion inhibitor 8 and the sealing material is not formed, and a gradient film is formed.

  Accordingly, an electrode corrosion inhibitor containing a siloxane compound composed of tetraalkoxysilane, methyltrialkoxysilane, (3-mercaptopropyl) trialkoxysilane is provided on one surface side (surface side in contact with the metal electrodes 4 and 5). And a sealing material containing a polysiloxane compound composed of tetraalkoxysilane, methyltrialkoxysilane and dialkoxydimethylsilane on the other surface side (the surface opposite to the surface in contact with the metal electrodes 4 and 5), It is possible to form a functionally gradient material in which the composition ratio of the siloxane compound and the polysiloxane compound is changed in an inclined manner from the surface side toward the other surface side.

  That is, in the functionally gradient material, the ratio of the composition constituting the electrode corrosion inhibitor 8 decreases stepwise or continuously from one surface side to the other surface side, and the composition constituting the sealing material The ratio of things increases stepwise or continuously.

  In addition, the mixing ratio of a silane agent is an example and is not limited to this. Moreover, although the example which used acetic acid as a catalyst was shown, you may use other acid catalysts, such as hydrochloric acid, and a base catalyst. For example, when the molar ratio of tetraethoxysilane and methyltriethoxysilane is 1, the molar ratio of diethoxydimethylsilane may be 78 to 156. The molar ratio of water may be changed as appropriate, and the molar ratio of acetic acid may be changed in accordance with the molar ratio of water.

  The functionally gradient material is a mixture of diethoxydimethylsilane: tetraethoxysilane: methyltriethoxysilane = 78: 1: 1 (molar ratio), stirred at 80 ° C. for 20 minutes, and then irradiated with microwaves at 500 W for 20 minutes. Further, it may be formed by stirring at 150 ° C. for 6 hours. Note that water and acetic acid are added as appropriate, as in the case of forming without using a microwave. The amount of acetic acid can be changed according to the amount of water.

  By irradiating the microwave, the formation time of the sealing layer 9 can be shortened. In this example, the irradiation was performed under the condition of irradiation at 500 W for 20 minutes, but a desired functionally gradient material can be obtained by appropriately changing the irradiation time and energy according to the stirring capacity and irradiation state.

  The functionally gradient material may contain a curing agent or a curing catalyst. Thereby, it can be hardened reliably. Curing catalysts include tin octylate, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin marker peptide, dibutyltin thiocarboxylate, dibutyltin dimaleate, dibutyltin oxide, monobutyltin oxide, dioctyltin thiocarboxylate, dioctyltin Organic tin compounds such as marker peptide, organic lead compounds such as lead octenoate, organic mercury compounds such as phenylmercury propionate, organic antimony compounds, potassium, sodium, calcium, iron, magnesium, mercury, nickel, cobalt, zinc, Examples thereof include carboxylates such as aluminum, tin, vanadium, and titanium, amine salts such as dibutyltinamine-2-ethylhexoate, and other acidic and basic catalysts.

  Although not particularly limited, an organic tin compound is preferable as the curing catalyst. For example, 0.001 to 5% by weight of these catalysts can be blended with respect to a specific organic polysiloxane.

  The functionally gradient material is transparent, but a mixture such as a phosphor may be mixed in order to convert the color of light emitted from the optical semiconductor element 6.

  Up to this point, the structure of one light emitting device has been described. However, when carrying out the invention according to the present embodiment, it is possible to perform processing in units of wafers, which can be realized at low cost.

  Further, the structure of the light emitting device 1 is not limited to that shown in FIG. 4, and for example, the structure shown in FIGS. 5-8 is a schematic sectional drawing which shows another embodiment of the light-emitting device of this invention.

5 and 6 are schematic cross-sectional views showing another embodiment of the light-emitting device of the present invention.
FIG. 5 is a schematic cross-sectional view showing an electrode corrosion inhibitor coating step in another embodiment of the light emitting device of the present invention.

  5 is different from FIG. 4 in that the electrode corrosion inhibitor 8 covers not only the metal electrodes 4 and 5 but also the entire reflecting member 2.

  The electrode corrosion inhibitor formed in the present invention is a transparent body and has good transmittance. Therefore, the electrode corrosion inhibitor 8 may cover the reflecting member 2. By comprising in this way, it becomes possible to form the electrode corrosion inhibitor 8 easily at the time of manufacture in a wafer unit.

  FIG. 6 shows a light emitting device that has undergone the electrode corrosion inhibitor coating step shown in FIG. At this time, in FIG. 6, the electrode corrosion inhibitor is partially formed on the surface of the reflecting member 2 opposite to the surface in contact with the substrate 3. Since this does not hinder the performance of the light emitting device 1, it is not necessarily removed by peeling or the like. In this case, since it is not necessary to adjust the application area | region of the electrode corrosion inhibitor 8 with a mask etc., an electrode corrosion inhibitor application | coating process can be simplified.

7 and 8 are schematic cross-sectional views showing another embodiment of the light-emitting device of the present invention.
FIG. 7 is a schematic cross-sectional view showing an electrode corrosion inhibitor coating step in another embodiment of the light emitting device of the present invention.

  In FIG. 7, the light emitting device 1 includes a substrate 3 having a depression at the center, an optical semiconductor element 6 mounted on the bottom of the depression provided at the center on one surface side of the substrate 3, and It is composed of metal electrodes 14 and 15 that are internal electrodes that are formed on the substrate 3 and are electrically connected to the optical semiconductor element 6, and an electrode corrosion inhibitor 8 that covers the metal electrodes 14 and 15.

  Further, the external electrodes 11 and 12 and the metal electrodes 14 and 15 formed on the surface opposite to the one surface of the substrate 3 are connected by the through electrode 13. Moreover, the wall part of the hollow part of the board | substrate 3 is formed in the inclined surface. In addition, a reflective film 16 made of silver is formed on the wall surface of the recess to efficiently radiate light from the optical semiconductor element 6. The optical semiconductor element 6 and the metal electrode 14 are joined by silver paste or the like, and the optical semiconductor element 6 and the internal electrode 15 are connected by a wire bond 7.

  The electrode corrosion inhibitor 8 further covers the exposed portion of the reflective film 16, the wall surface of the recessed portion of the substrate 3, and one surface of the substrate 3.

  In the present embodiment as well, the metal electrodes 14 and 15 need only be covered with the electrode corrosion inhibitor 8, and corrosion of the metal electrodes 14 and 15 can be prevented.

FIG. 8 shows a light-emitting device that has undergone the electrode corrosion inhibitor coating step shown in FIG.
As shown in FIG. 8, the light emitting device 1 in which the concave shape is sealed with the functionally gradient material is formed. Similar to FIG. 6, a partial electrode corrosion inhibitor 8 is formed on the surface of the substrate 3 opposite to the surface on which the external electrodes are formed. Since this does not hinder the performance of the light emitting device 1, it is not necessarily removed by peeling or the like.

  FIG. 9 is a cross-sectional observation view of the light-emitting device manufactured according to the present embodiment. FIG. 10 is a cross-sectional observation view of a conventional light-emitting device manufactured for comparison.

  In the light-emitting device shown in FIG. 9, a multilayer reflective film 16 is formed on a substrate 3, and a sealing layer 9 made of a functionally gradient material is further formed. Here, in the sealing layer 9, the surface on the reflective film 16 side is composed of an electrode corrosion inhibitor, and the opposite surface (not shown), that is, the surface on which the striped pattern in the figure appears is composed of a sealing material. ing.

  In the conventional light emitting device shown in FIG. 10, a multilayer reflective film 16 is formed on a substrate 3, a precoat layer 8 is applied, and a silicone resin 17 is further applied and cured.

  As shown in FIG. 9, in the sealing layer 9, the interface between the electrode corrosion inhibitor and the sealing material is unclear at the peripheral portion 18 of the reflective film 16. Therefore, according to this embodiment, it can be confirmed that the sealing layer 9 made of a functionally gradient material having a gradient film is formed.

  On the other hand, in FIG. 10, it can be confirmed that the interface between the precoat layer 8 and the silicone resin 17 clearly appears. In FIG. 9, such an interface does not appear in the sealing layer 9.

[Corrosion resistance test]
Hereinafter, the present invention will be described more specifically by a corrosive test in a light emitting device, but the present invention is not limited to the following test examples.

  A light emitting device sealed with a commercially available silicone resin (KER2500; Shin-Etsu silicone) is directly prepared on the substrate 3 on which the light emitting device 1 and the optical semiconductor element 6 are mounted in the present invention. The container was sealed and allowed to stand at 70 ° C., and the degree of corrosion of the silver electrode sealed after one day was visually observed. The results are shown in Table 1.

  In Table 1, “◯” indicates “no corrosion (discoloration)”, and “x” indicates “black discoloration”. As shown in Table 1, the light emitting device using KER2500 was blackened, whereas the light emitting device of the present invention did not change color.

[Permeability test]
The electrode corrosion inhibitor of the present invention is applied onto quartz glass, and the sealing material of the present invention is applied to a thickness of 1.5 mm on the electrode corrosion inhibitor that has been left for 5 minutes at 80 ° C. to remove the solvent. Then, a sample that was allowed to stand at 150 ° C. for 2 hours and a sample in which a commercially available silicone resin (KER2500; Shin-Etsu Silicone) was applied to quartz glass to a thickness of 1.5 mm were cured. The transmittance of these samples at a wavelength of 450 nm was measured using quartz glass as a blank (control). The results are shown in Table 2.

  In Table 2, “◯” indicates “transmittance of 90% or more”, and “x” indicates “transmittance of less than 90%”.

[Light resistance test]
A sample similar to the permeability test was prepared, and the transmittance at a wavelength of 450 nm was measured. After irradiating with ultraviolet rays for 100 hours using an ultraviolet long life carbon arc lamp, the transmittance at a wavelength of 450 nm was measured again to determine the rate of change. The results are shown in Table 2.

  In Table 2, “◯” indicates “change rate of less than 10%”, and “x” indicates “change rate of 10% or more”.

  As shown in Tables 1 and 2, the light-emitting device provided with the sealing layer made of the functionally graded material according to the present invention was excellent in corrosivity and confirmed the effect of light resistance.

  Moreover, the functionally gradient material of the present invention can be used for an optical device having an electrode other than a light emitting device. At this time, the electrode can be protected from corrosion by covering the electrode with the sealing layer formed of the functionally gradient material of the present invention.

DESCRIPTION OF SYMBOLS 1 Light emitting device 2 Reflective member 3 Board | substrate 4, 5 Metal electrode 6 Optical semiconductor element 7 Wire bond 8 Electrode corrosion inhibitor 9 Sealing layer 11, 12 External electrode 13 Through electrode 14, 15 Metal electrode 16 Reflective film 17 Silicone resin

Claims (7)

In an optical device having a metal electrode,
The metal electrode has an electrode corrosion inhibitor containing a siloxane compound composed of tetraalkoxysilane, methyltrialkoxysilane, and (3-mercaptopropyl) trialkoxysilane on the side in contact with the metal electrode, and is in contact with the metal electrode A sealing material containing a polysiloxane compound composed of tetraalkoxysilane, methyltrialkoxysilane, dialkoxydimethylsilane is provided on the surface opposite to the surface, and from the surface in contact with the metal electrode toward the opposite surface. An optical device characterized by being covered with a sealing layer formed of a functionally gradient material, wherein the composition ratio of the siloxane compound and the polysiloxane compound changes in a gradient manner. The siloxane compound is a compound obtained by mixing tetraethoxysilane: methyltriethoxysilane: (3-mercaptopropyl) triethoxysilane in a molar ratio of 30-60: 30-60: 1,
2. The optical device according to claim 1, wherein the polysiloxane compound is a compound in which diethoxydimethylsilane: tetraethoxysilane: methyltriethoxysilane is mixed at a molar ratio of 78 to 156: 1: 1. A substrate, an optical semiconductor element mounted on the substrate, a metal electrode formed on the substrate and electrically connected to the optical semiconductor element, a sealing layer covering the optical semiconductor element and the metal electrode, A light emitting device comprising:
The sealing layer has an electrode corrosion inhibitor containing a siloxane compound composed of tetraalkoxysilane, methyltrialkoxysilane, and (3-mercaptopropyl) trialkoxysilane on the side in contact with the metal electrode, and the metal electrode has A sealing material containing a polysiloxane compound composed of tetraalkoxysilane, methyltrialkoxysilane, dialkoxydimethylsilane is provided on the surface opposite to the surface in contact with the surface, and the surface facing the metal electrode is directed to the surface opposite to the surface. A light-emitting device, wherein the composition ratio of the siloxane compound and the polysiloxane compound is changed in a gradient manner. The siloxane compound is a compound obtained by mixing tetraethoxysilane: methyltriethoxysilane: (3-mercaptopropyl) triethoxysilane in a molar ratio of 30-60: 30-60: 1,
4. The light emitting device according to claim 3, wherein the polysiloxane compound is a compound in which diethoxydimethylsilane: tetraethoxysilane: methyltriethoxysilane is mixed at a molar ratio of 78 to 156: 1: 1. An electrode corrosion inhibitor coating step of applying an electrode corrosion inhibitor containing a siloxane compound composed of tetraalkoxysilane, methyltrialkoxysilane, (3-mercaptopropyl) trialkoxysilane on a metal electrode;
A sealing material coating step of coating a sealing material containing a polysiloxane compound comprising tetraalkoxysilane, methyltrialkoxysilane, dialkoxydimethylsilane on the electrode corrosion inhibitor;
A method for producing a functionally gradient material, comprising: a curing step of simultaneously curing the electrode corrosion inhibitor and the sealing material.   The method for producing a functionally gradient material according to claim 5, wherein microwaves are irradiated in the curing step.   The method for producing a functionally gradient material according to claim 5 or 6, wherein, in the electrode corrosion inhibitor coating step, the electrode corrosion inhibitor is applied in a thickness of 0.5 to 6 µm.