JP2017075203A - Sealing material for deep ultraviolet light, deep ultraviolet light emitting device and method for producing deep ultraviolet light emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealing material for deep ultraviolet light and a deep ultraviolet light emitting device.SOLUTION: A sealing material for deep ultraviolet light is predominantly composed of polyorganosiloxane in which a ratio of the number of carbon-carbon bonds to the number of Si atoms is 5% or less. A side chain of the polyorganosiloxane is a methyl group or a trimethylsilyloxy group.SELECTED DRAWING: None

Description

  The present application relates to a sealing material for deep ultraviolet light, a deep ultraviolet light emitting device, and a manufacturing method of the deep ultraviolet light emitting device.

  In accordance with advances in semiconductor technology, light-emitting elements that emit light in various wavelength bands have been developed, and products for applications corresponding to the characteristics of the emission wavelength have been put into practical use.

  It is known that deep ultraviolet light having a wavelength of about 200 nm to 350 nm is damaging to biological DNA, RNA, and the like. For this reason, light emitting elements that emit deep ultraviolet light have been developed and used for sterilization, water purification, and the like. Deep ultraviolet light is also used for phototherapy in the medical field, environmental measurement in the environmental field, measurement in the industrial field, resin curing, adhesion, and the like.

  Conventionally, mercury lamps have been widely used as light sources for deep ultraviolet light. However, regulations on environmentally hazardous substances such as mercury are becoming stricter from the viewpoint of environmental impact. For this reason, LEDs and semiconductor lasers have attracted attention as light sources that can replace mercury lamps, and deep ultraviolet light-emitting elements having various semiconductor materials and light-emitting structures have been developed.

  In order to increase the reliability of the deep ultraviolet light emitting element, it is necessary to seal the deep ultraviolet light emitting element with an appropriate structure and package it. For example, Patent Document 1 discloses a semiconductor module in which a deep ultraviolet LED using aluminum gallium nitride is sealed with a ceramic substrate and a window member such as quartz or sapphire.

JP 2015-18873 A

  One non-limiting exemplary embodiment of the present application provides a deep ultraviolet light sealing material, a deep ultraviolet light emitting device, and a method of manufacturing the deep ultraviolet light emitting device.

  The deep ultraviolet light sealing material according to an embodiment of the present application contains, as a main component, a polyorganosiloxane in which the ratio of the number of carbon-carbon bonds to the number of Si atoms is 5% or less.

  The side chain of the polyorganosiloxane may be a methyl group or a trimethylsilyloxy group.

The polyorganosiloxane may be represented by the following average composition formula (1).

Here, R ¹ , R ² , and R ³ are each independently a methyl group or a trimethylsilyloxy group, X represents a bond of a branch of the main chain, and m, n, and p are m / (m + n + p). ≧ 0.6 and n + p ≠ 0 are satisfied. A part of the methyl group and the trimethylsilyloxy group may be substituted with a hydroxyl group.

  The number average molecular weight of the polyorganosiloxane may be 500 or more and 5000 or less.

  It may further contain as a main component a filler that is dispersed in the polyorganosiloxane and has a transmittance of 50% or more in a wavelength range of 200 nm to 350 nm.

  It may be dispersed in the polyorganosiloxane and may further contain as a main component a filler composed of one selected from the group consisting of calcium fluoride, quartz, sapphire, and silicon dioxide.

  The filler may be contained in a proportion of 40 vol% or more and 93 vol% or less with respect to the polyorganosiloxane.

  A deep ultraviolet light emitting device according to an embodiment of the present application is disposed on a substrate, has at least one deep ultraviolet light emitting element chip having an emission surface, and is disposed on the substrate. A sealing body made of a stop material, the sealing body being disposed so as to cover the emission surface of the at least one deep ultraviolet light emitting element chip.

  A method for manufacturing a deep ultraviolet light emitting device according to an embodiment of the present application includes a step of hydrolyzing an organoalkoxysilane and dehydrating and condensing the decomposition product to form a polymer; And a step of forming a sealing body covering the deep ultraviolet light emitting element chip by curing the polymer, wherein the sealing body includes carbon-carbon relative to the number of Si atoms. A polyorganosiloxane having a bond number ratio of 5% or less is contained as a main component.

  The organoalkoxysilane may include tetraethyl orthosilicate, methyltrialkoxysilane, and dimethyl dialkoxysilane.

  A step of irradiating the sealing body with ultraviolet rays may be further included.

  According to the sealing material for deep ultraviolet light of the present embodiment, it contains polyorganosiloxane having no carbon-carbon bond in the side chain as a main component, so that it transmits deep ultraviolet light and is deteriorated by deep ultraviolet light. Is suppressed. By using this deep ultraviolet light sealing material, it is possible to realize a deep ultraviolet light emitting device that has a sealing body that covers the emission surface of the deep ultraviolet light emitting element chip and emits deep ultraviolet light to the outside with high efficiency. It becomes.

FIG. 1A is a cross-sectional view showing an example of the deep ultraviolet light emitting device of this embodiment. FIG. 1B is a cross-sectional view showing another example of the deep ultraviolet light emitting device of this embodiment. FIG. 2 is a diagram for explaining the main chain and side chain of the polymer in the present application. FIG. 3 is a diagram showing the deep ultraviolet light transmission characteristics of the deep ultraviolet light sealing material of the example. FIG. 4 is a cross-sectional view showing an example of a conventional deep ultraviolet light emitting device.

  The inventor of the present application examined the conventional deep ultraviolet light emitting module in detail. FIG. 4 schematically shows the structure of a conventional deep ultraviolet light emitting module disclosed in Patent Document 1. The conventional deep ultraviolet light emitting module 101 includes a substrate 110 and a light emitting element 114 disposed in a recess 110r of the substrate 110 via a submount 112. A window member 116 is disposed in the opening of the recess 110r, and the window member 116 and the substrate 110 are sealed with a sealing material 118. The window member 116 is formed of a material that can transmit deep ultraviolet light, such as quartz or sapphire.

  According to this structure, deep ultraviolet light is hardly absorbed by the window member 116 and is transmitted. However, Fresnel reflection occurs due to a difference in refractive index between the window member 116 and the gas 120 such as air confined in the recess 110 r and the external air 122 on the upper surface 116 a and the lower surface 116 b of the window member 116, and is emitted from the light emitting element 114. A part of the reflected light is reflected inside and is not emitted outside. In particular, it has been found that the output efficiency is not sufficiently high due to reflection on the lower surface 116b.

  In order to reduce internal reflection, for example, it is conceivable to seal the surface of the light emitting element with a resin like a conventional LED module that emits visible light. However, a sealing material used in a conventional light emitting element that emits visible light absorbs deep ultraviolet light and deteriorates. For this reason, it is difficult to ensure reliability over a long period of time. For example, an epoxy resin generally used as a sealing material easily absorbs ultraviolet rays and deteriorates in a short period of time.

  In view of such problems, the inventor of the present application has conceived a novel sealing material for deep ultraviolet light and a deep ultraviolet light emitting device. Hereinafter, an example of the deep ultraviolet light sealing material and the deep ultraviolet light emitting device of the present embodiment will be described in detail. In the present application, deep ultraviolet light refers to electromagnetic waves having a wavelength of about 200 nm to about 350 nm. The electromagnetic waves in this region are generally not visible to the human eye, but are called “light” as well as visible light.

  FIG. 1A is a cross-sectional view showing an example of a deep ultraviolet light sealing material and a deep ultraviolet light emitting device of the present embodiment. The deep ultraviolet light emitting device 11 includes a substrate 12, at least one deep ultraviolet light emitting element chip 15, a dam 16, and a sealing body 23.

  The substrate 12 has an upper surface 12a and a lower surface 12b, and the deep ultraviolet light emitting element chip 15 is disposed on the upper surface 12a. The substrate 12 includes, for example, a terminal 17 for supplying power to the deep ultraviolet light emitting element chip 15 on the upper surface 12a, an electrode electrically connected to the deep ultraviolet light emitting element chip 15, and a conductive pattern 18 connecting these. A ceramic circuit board may also be used.

  The deep ultraviolet light-emitting element chip 15 is, for example, an LED or a laser diode configured with a compound semiconductor. Specifically, the deep ultraviolet light emitting element chip 15 is made of, for example, an AlGaN semiconductor, and emits light having a wavelength of 200 nm or more and 350 nm or less. In FIG. 1A, three deep ultraviolet light emitting element chips 15 are shown, but the number of deep ultraviolet light emitting element chips 15 is determined according to the application of the deep ultraviolet light emitting device 11.

  A dam 16 surrounding the deep ultraviolet light emitting element chip 15 is provided on the upper surface 12 a of the substrate 12. The dam 16 has heat resistance and high reflectivity. The dam 16 is made of, for example, aluminum or aluminum oxide. The height of the dam 16 is preferably larger than the height of the deep ultraviolet light emitting element chip 15 disposed on the substrate 12. Further, the deep ultraviolet light emitting device 11 may include a reflecting mirror instead of the dam 16 or may not include both.

  On the lower surface 12b of the substrate 12, for example, a heat conductive layer 13 having high heat conductivity may be provided. The heat conductive layer 13 is comprised by the silicon nitride thin film etc., for example. The deep ultraviolet light emitting device 11 may further include a metal layer 14 on the surface opposite to the surface in contact with the substrate 12 of the heat conductive layer 13. The metal layer 14 is formed of, for example, copper, and is connected to a surface on which the deep ultraviolet light emitting device 11 is mounted by solder or the like.

  A sealing body 23 is located in a region surrounded by the dam 16 on the upper surface 12a. The sealing body 23 is disposed on the upper surface 12 a of the substrate 12 so as to cover the emission surface 15 a of the deep ultraviolet light emitting element chip 15. In the present embodiment, the upper surface 23a of the sealing body 23 is a gentle partial spherical surface or curved surface that is recessed upward, but may have a shape according to the application of the deep ultraviolet light emitting device 11 and the light distribution.

  The sealing body 23 is formed from the deep ultraviolet light sealing material 22. The deep ultraviolet light sealing material 22 contains polyorganosiloxane 20 as a main component. Here, the main component means that the polyorganosiloxane 20 is contained in a ratio of 90 vol% or more with respect to the whole deep ultraviolet light sealing material 22.

  The polyorganosiloxane 20 is an organosilicon polymer whose main chain is mainly composed of siloxane bonds ((Si—O) n). In the present application, the “main chain” includes not only the longest molecular chain but also branched oligomer molecular chains and polymer molecular chains. The oligomer molecular chain and the polymer molecular chain are also constituted by siloxane bonds. The main chain may contain Si—Si bonds generated by side reactions during the synthesis reaction. As shown in FIG. 2, the side branch R ′ protruding from the “main chain” is referred to as a side chain.

  The polyorganosiloxane 20 has little or no carbon-carbon bond in the side chain. Specifically, the polyorganosiloxane 20 contains only a methyl group or a trimethylsilyloxy group as a side chain. Here, “has little or no carbon-carbon bond” is unavoidably a substituent having a carbon-carbon bond as an impurity contained in the raw material, and will be described below. In the synthesis of the polyorganosiloxane 20, it is meant that a substituent having a carbon-carbon bond (single bond and double bond) that can be generated as a side reaction of the synthesis reaction can be included. In the present specification, the “carbon-carbon bond” includes a single bond and a double bond. Even when carbon-carbon bonds are intentionally introduced into the side chain, the ratio of the number of carbon-carbon bonds to the number of Si atoms in the average composition formula (1) is 5% or less, as will be described below. , Preferably 2% or less, more preferably 0.2% or less.

Specifically, the polyorganosiloxane 20 is represented by the following average composition formula (1).

Here, R ¹ , R ² and R ³ are independently a methyl group (CH ₃ ) or a trimethylsilyloxy group (OSi (CH ₃ ) ₃ ). A part of the methyl group in the methyl group and the trimethylsilyloxy group may be substituted with a hydroxyl group (OH). That is, R ¹ , R ² and R ³ are independently methyl group (CH ₃ ), hydroxy group (OH), trimethylsilyloxy group (OSi (CH ₃ ) ₃ ), hydroxydimethylsilyloxy group (OSi (CH ₃ )). ₂ OH), a dihydroxymethylsilyloxy group (OSiCH ₃ (OH) ₂ ), and a trihydroxysylsilyloxy group (OSi (OH) ₃ ). X represents a bond of a branch of the main chain according to the definition described above. In the formula (1), R ^{1 to} R ³ are side chains as defined above. M, n, and p represent the ratio of the number of units each having R ¹ R ² (SiO), R ³ X (SiO), and X ₂ (SiO) as units. The average composition formula (1) only shows the ratio of the number of units represented by m, n, and p. The average composition formula (1) is the order in which each unit is shown in the average composition formula (1). It does not mean that they are adjacent. The end groups are not shown.

In the polyorganosiloxane 20 represented by the average composition formula (1), when the number of units containing X in one molecule, that is, the ratio of n and p to the total of m, n, and p increases, A large number of three-dimensionally linked three-dimensional structures are included, and flexibility is reduced. For this reason, it is preferable that the ratio of n and p is small and the ratio of m is large with respect to the total of m, n and p. Specifically, m, n, and p preferably satisfy m / (m + n + p) ≧ 0.6. Further, n + p ≠ 0. When the unit of R ³ X (SiO) and X ₂ (SiO) is not included at all, there is no cross-linking or branching in the molecule of the polyorganosiloxane 20, and there is almost no entanglement between the molecules. For this reason, the polyorganosiloxane 20 is unlikely to be a stable solid at room temperature, and may not be suitable as a sealing material. m, n, and p are more preferably m / (m + n + p) ≧ 0.7. Moreover, it is more preferable that the total of R ³ X (SiO) and X ₂ (SiO) units in the molecule of the polyorganosiloxane 20 is 2 or more.

The average composition formula (1) is obtained by, for example, R ¹ R ³ (SiO), R ³ X (SiO), and X ₂ determined by the number average molecular weight of the synthesized polyorganosiloxane 20, NMR, mass spectrometry, GPC, and the like. It can be determined from the ratio of each unit of (SiO).

  The number average molecular weight of the polyorganosiloxane 20 is preferably about 500 or more and 5000 or less. When the number average molecular weight is less than 500, the volatility of the polyorganosiloxane 20 is undesirably high. On the other hand, when the number average molecular weight is larger than 5000, the hardness of the polyorganosiloxane 20 becomes too high, and it becomes difficult to form the sealing body 23. Here, the number average molecular weight is a value measured by gel permeation chromatography. The refractive index of the polyorganosiloxane 20 is, for example, about 1.35 or more and 1.5 or less. Trimethylsilyloxy groups can be introduced for control of the number of branches.

  An organic compound having a carbon-carbon bond absorbs deep ultraviolet light and decomposes when the carbon-carbon bond is broken. For this reason, when an epoxy resin generally used as a sealing material for a visible light emitting element is used as a sealing material for a deep ultraviolet light emitting element, it deteriorates in a short time. This is because the epoxy resin contains many cross-linked structures, and the carbon-carbon bond of the cross-linked structure is cleaved by ultraviolet rays. On the other hand, the main chain of the polyorganosiloxane 20 is constituted by a siloxane bond, and the side chain does not contain a carbon-carbon bond. Therefore, the polyorganosiloxane 20 hardly absorbs deep ultraviolet light, and does not change color or deteriorate even if deep ultraviolet light is transmitted.

  The sealing body 23 made of the deep ultraviolet light sealing material 22 containing the polyorganosiloxane 20 as a main component transmits light emitted from the deep ultraviolet light emitting element chip 15 and allows the deep ultraviolet light emitting element chip 15 to be exposed from the external environment. Can be protected. Since it is hardly deteriorated by deep ultraviolet light, the light emission characteristics hardly change over a long period of time, and the deep ultraviolet light emitting element chip 15 is continuously protected. Therefore, the deep ultraviolet light emitting device 11 can have high reliability.

  Moreover, since the sealing body 23 covers the emission surface 15a of the deep ultraviolet light emitting element chip 15, almost no internal reflection occurs between the sealing body 23 and the interface between the external environment. For this reason, the deep ultraviolet light emitting device 11 can emit deep ultraviolet light with high external extraction efficiency.

  In the polyorganosiloxane 20, the methyl group contained in the side chain is bonded to silicon and has a Si—C bond. This Si—C bond is considered to absorb and cut off part of the light in the ultraviolet wavelength band. Due to this light absorption, the transmittance of the polyorganosiloxane 20 in the ultraviolet region can be lowered. The inventor of the present application converts the Si—C bond to the Si—O bond by forming the deep ultraviolet light sealing material 22 containing the polyorganosiloxane 20 and then irradiating with ultraviolet rays before use. It has been found that the transmittance in the ultraviolet region can be improved.

According to a detailed study, when the polyorganosiloxane 20 is irradiated with ultraviolet rays, the Si—C bond between the silicon-bonded methyl groups is broken. At this time, the cleaved bond reacts with moisture in the air, the cleaved methyl group is released as methane, and the hydroxyl group is bonded to silicon. That is, it is considered that the following substitution reaction occurs due to ultraviolet rays.
Si—CH ₃ + H ₂ O → Si—OH + CH ₄

  This reaction in the polyorganosiloxane 20 is a side chain substitution reaction that does not cause a change in the skeletal structure, unlike the cleavage of the crosslinked structure. Further, since the bond dissociation energy of the generated Si—O bond is larger than that of the Si—C bond, the Si—O bond is not easily broken by ultraviolet rays. Therefore, by irradiating with ultraviolet rays, the methyl groups in the side chain of polyorganosiloxane 20 and the methyl groups in the trimethylsilyloxy group are replaced with hydroxyl groups, thereby providing a deep ultraviolet light envelope having a stable and higher transmittance in the ultraviolet region. A stop material 22 can be obtained.

  The ultraviolet rays irradiated for the side chain substitution reaction described above may be in the wavelength range of 220 nm to 365 nm. When the ultraviolet ray is irradiated for about 1 minute, the transmittance of the polyorganosiloxane 20 in the ultraviolet region is significantly improved. In order to produce a remarkable transmittance improvement effect, it is preferable that the ultraviolet irradiation before use is, for example, 1 hour or longer. Moreover, when the ultraviolet rays are irradiated for about 100 hours, the effect of improving the transmittance is saturated.

  The light transmittance of the polyorganosiloxane 20 can be increased over the entire range of 200 nm to 350 nm by irradiation with ultraviolet rays. In particular, the transmissivity can be improved by 10% or more in the range of 200 nm to 270 nm.

  The high transmittance is an effect obtained by the fact that the side chain of the polyorganosiloxane 20 has a Si—O bond. For this reason, in the polyorganosiloxane 20 contained in the deep ultraviolet light sealing material 22 of the present embodiment, it is not necessary that the hydroxy group of the side chain is actually substituted with a methyl group. However, as will be described below, it is generally difficult to polymerize the monomer while maintaining the hydroxy group bonded to the monomer silicon during the synthesis of the polyorganosiloxane 20. For this reason, it is preferable to introduce Si—O bonds by the above-described irradiation of ultraviolet rays.

  FIG. 1B shows another embodiment of the deep ultraviolet light emitting device. As described above, in the average composition formula (1), when there are many Xs that are branched bonds, the polyorganosiloxane 20 has more three-dimensionally bonded three-dimensional structures, and the flexibility is lowered. As a result, the sealing body 23 may be easily cracked when the sealing body 23 is formed. In the deep ultraviolet light emitting device 11 ′ shown in FIG. 1B, the deep ultraviolet light sealing material 22 further includes a filler 21 as a main component in addition to the polyorganosiloxane 20 in order to suppress the formation of cracks. The filler 21 is dispersed in the polyorganosiloxane 20.

  Since the filler 21 does not shrink when the sealing body 23 is formed, the deep ultraviolet light sealing material 22 contains the filler 21 to suppress shrinkage of the entire sealing body 23 due to polymerization or crosslinking of the polyorganosiloxane 20, The crack which may arise in the sealing body 23 is suppressed. For this reason, as long as the deep ultraviolet light sealing material 22 is included, an effect of suppressing cracks can be obtained depending on the amount of addition. That is, the addition amount of the filler 21 should just be more than 0 vol% with respect to the whole deep ultraviolet light sealing material. In order to obtain a remarkable effect of suppressing cracks, the filler 21 is preferably contained at a ratio of 40 vol% or more with respect to the entire deep ultraviolet light sealing material.

  The filler 21 can be included at a ratio of 93 vol% or less with respect to the whole deep ultraviolet light sealing material. When the added amount of the filler 21 exceeds 93 vol%, a dense deep ultraviolet light emitting sealing material may not be obtained. When the sealing material 22 for deep ultraviolet light contains the filler 21 in the above-described proportion, the polyorganosiloxane 20 is the main component in the remaining part other than the filler 21, so that the polyorganosiloxane 20 is the remaining part other than the filler 21. 90 vol% or more is preferable. That is, considering the form shown in FIG. 1A together, the deep ultraviolet light sealing material 22 may contain the filler 21 in a ratio of 0 vol% or more and 93 vol% or less, and in a ratio of 40 vol% or more and 93 vol% or less. More preferably.

  The filler 21 is preferably made of a material that transmits deep ultraviolet light well. For example, the filler 21 preferably has a transmittance of 50% or more, and more preferably has a transmittance of 85% or more in a wavelength range of 200 nm or more and 350 nm or less. As a material having such transmittance, for example, calcium fluoride, sapphire, silicon dioxide, silicone such as polydimethylsilicone, optical glass, or the like can be used. The particle size and shape of the filler 21 are not particularly limited, and particles having various particle shapes such as a spherical shape, a needle shape, and a plate shape can be used.

  From the viewpoint of suppressing reflection of deep ultraviolet light emitted from the deep ultraviolet light emitting element chip 15 at the interface between the filler 21 and the polyorganosiloxane 20, the refractive index of the filler 21 is approximately the same as the refractive index of the polyorganosiloxane 20. Preferably there is. Specifically, the refractive index of the filler 21 is, for example, about 1.3 or more and 1.6 or less.

  As described above, when the deep ultraviolet light sealing material further includes the filler 21, the moldability particularly when the sealing body 23 is formed is improved. For this reason, it becomes possible to form the sealing body 23 of various shapes using the sealing material for deep ultraviolet light.

  The deep ultraviolet light sealing material 22 may contain additives other than the polyorganosiloxane 20 and the filler 21 as subcomponents. When the filler 21 is not included, the additive is preferably 10 vol% or less with respect to the entire deep ultraviolet light sealing material. Moreover, when the filler 21 is included, it is preferable that an additive is 10 vol% or less among remainders other than the filler 21. FIG. Examples of the additive include 3-mercapto-1-propanol for improving adhesion with the electrode.

Further, as described above, it is preferable that the polyorganosiloxane 20 represented by the average composition formula (1) does not contain a carbon-carbon bond from the viewpoint of deterioration due to deep ultraviolet light. However, in the case where an effect such as improvement of other characteristics by introducing a substituent containing a carbon-carbon bond into the side chain can be obtained, polyorganosiloxane is within a range in which the decrease in resistance to deep ultraviolet light is not significant. A substituent containing a carbon-carbon bond may be introduced into the 20 side chains. Specifically, in the average composition formula (1), at least one of R ¹ , R ² and R ³ may be a substituent containing a carbon-carbon bond. For example, when a mercapto group is introduced as a substituent, the effect of improving the wettability of the deep ultraviolet light sealing material to the electrode can be obtained. In this case, the ratio of the number of carbon-carbon bonds to the number of Si atoms in the average composition formula (1) is 5% or less, preferably 2% or less, so that sufficient resistance to deep ultraviolet light can be secured. Preferably, it is 0.2% or less.

  Next, an embodiment of a method for manufacturing the sealing body 23 and the deep ultraviolet light emitting device 11 will be described. The sealing body 23 can be formed in the deep ultraviolet light emitting device 11 by, for example, hydrolysis and dehydration condensation reaction of organoalkoxysilane.

(1) Preparation of organoalkoxysilane First, an organoalkoxysilane is prepared. Specifically, tetraethyl orthosilicate, methyltrialkoxysilane, and dimethyldialkoxysilane are prepared as starting compounds. By adjusting the molar ratio of these starting compounds, p, n, and m in the average composition formula (1) can be adjusted.

  The alkyl part of the alkoxyl group is eliminated by hydrolysis and is not theoretically included in the polyorganosiloxane 20. However, it may be contained in the polyorganosiloxane 20 due to rearrangement of substituents during the reaction, remaining as impurities, or contamination due to side reactions. For this reason, it is preferable that an alkoxyl group does not contain a CC bond, and it is preferable that it is a methoxy group. That is, it is preferable to use methyltrimethoxysilane and dimethyldimethoxysilane. The ratios of tetraethyl orthosilicate, methyltrialkoxysilane, and dimethyldialkoxysilane depend on the size of the sealing body 23 to be formed, the required manufacturing conditions, and the like. When the ratio of tetraethylorthosilicate and methyltrialkoxysilane increases, the number of three-dimensional structures in the polyorganosiloxane 20 increases and the moldability decreases.

(2) Polymerization of organoalkoxysilane Addition of 0.05 to 10 mol of water under acidity with respect to a total of 1 mol of the above-mentioned alkoxysilane, the mixture is kept at 20 to 80 ° C. and stirred, thereby hydrolyzing the alkoxysilane. Disassemble. Thereby, methyltrihydroxysilane and dimethyldihydroxysilane are produced.

  Next, when forming the sealing body 23 with the sealing material for deep ultraviolet light containing the filler 21, the filler 21 is added to a hydrolyzate.

  By further stirring the hydrolyzate, dehydration condensation in which one molecule of water is eliminated from the two hydroxy groups of two molecules of hydroxysilane occurs, and hydroxysilane is polymerized. In order to control the degree of polymerization, control the number of branches during dehydration condensation, and suppress the formation of a three-dimensional structure, a silane coupling agent may be added at an appropriate stage to suppress the dehydration condensation reaction.

(3) Placement and curing of polymer on deep ultraviolet light-emitting element chip When the polymer has an appropriate viscosity, the polymer is placed in the dam 16 of the substrate 12 as shown in FIG. 1A or 1B. To do.

  Thereafter, by holding in the atmosphere at 150 to 300 ° C., for example, for 10 minutes to 2 hours, the dehydration condensation is completed and the polymer is cured. At the same time, the reaction products water and alcohol are removed. Thereby, a by-product is removed, and polyorganosiloxane 20 having sufficient strength and density as a protective material is generated. At the same time, a sealing body 23 covering the deep ultraviolet light emitting element chip 15 is formed.

(4) Ultraviolet irradiation As necessary, the sealing body 23 is irradiated with ultraviolet rays in order to increase the transmittance of the sealing body 23 in the ultraviolet region. The sealing body 23 is irradiated with ultraviolet rays having a wavelength range of 220 nm to 365 nm within a range of 1 minute to 100 hours. Thereby, the transmittance | permeability of the ultraviolet region of the polyorganosiloxane 20 in a sealing body is raised.

  As described above, according to the sealing material for deep ultraviolet light of the present embodiment, since the polyorganosiloxane having no carbon-carbon bond in the side chain is contained as a main component, it transmits deep ultraviolet light, and Deterioration due to deep ultraviolet light is suppressed. Therefore, it can be suitably used as a sealing material for deep ultraviolet light emitting elements. When the deep ultraviolet light sealing material further contains a filler, the moldability is improved. Further, according to the deep ultraviolet light emitting device of the present embodiment, a sealing body made of a sealing material for an ultraviolet light emitting element containing polyorganosiloxane as a main component is disposed so as to cover the emission surface of the deep ultraviolet light emitting element chip. Therefore, internal reflection of deep ultraviolet light emitted from the emission surface is suppressed, and deep ultraviolet light can be emitted to the outside with high efficiency.

  The deep ultraviolet light emitting device of the present embodiment includes a deep ultraviolet light emitting element chip. However, the deep ultraviolet light emitting element of the present embodiment is not limited to the chip-shaped light emitting element. An encapsulating material may be used. For example, it can be suitably used as a sealing material for a large area deep ultraviolet light emitting device using microplasma.

  Furthermore, the sealing material or the sealing material filled between the members is not disposed at the position directly in contact with the light emitting element but on the path where the deep ultraviolet light emitted from the light emitting element is directly or indirectly irradiated. As the material, the deep ultraviolet light sealing material of the present embodiment can be suitably used. For example, the deep ultraviolet light sealing material of the present embodiment can be disposed on a member for holding the object and the light emitting element, and the object can be irradiated with deep ultraviolet light. Thereby, degradation by ultraviolet rays in facilities such as sterilization, phototherapy, environmental measurement, and resin curing can be suppressed.

(Example)
1. Sealing material for deep ultraviolet light that does not contain a filler The sealing material for deep ultraviolet light that does not contain a filler of the present embodiment (polyorganosiloxane represented by the average composition formula (1)) is prepared, and the transmittance of ultraviolet light is increased. The measurement results will be described.

  Hydrolysis was performed by mixing 4 mol of methyltrimethoxysilane and 1 mol of dimethyldimethoxysilane as starting materials, 20 mol of water and a small amount of acetic acid as a pH adjuster, and stirring and mixing at 70 ° C. for 2 hours. . Further, the mixture was stirred at 70 ° C. for 24 hours to perform dehydration condensation to obtain a solution.

  The obtained solution was applied to an aluminum substrate, dried, and held at 260 ° C. for 30 minutes to complete dehydration condensation. The sample obtained by removing from the aluminum substrate was used as Example 1. The thickness of the sample of Example 1 was measured with a constant pressure thickness measuring instrument. The thickness was 0.4 mm.

  A polyorganosiloxane was prepared by the same procedure as in Example 1, and a sample irradiated with ultraviolet rays having a wavelength of 254 nm for 48 hours was prepared. The obtained sample was taken as Example 2.

  For comparison, a Struers epoxy resin was prepared so as to be approximately the same as the thickness of the sample of Example 1, and a sample of a comparative example was obtained.

  The transmittance | permeability of the sample of Example 1 and the comparative example 1 was measured using Shimadzu Corporation ultraviolet visible spectrophotometer UV-3150. The measurement was performed at room temperature (25 ° C.), and the light intensity was determined by irradiating the sample with light having a wavelength of 200 nm to 1200 nm using a halogen lamp and a deuterium lamp. An air-only sample was measured as a standard sample, and the measurement results of the samples of Example 1 and Comparative Example 1 were corrected.

  The results are shown in FIG. From FIG. 3, it can be seen that the transmittance of the comparative example (epoxy resin) rapidly decreases at a wavelength of 300 nm or less, and is about 10% or less at a wavelength of 290 nm or less. On the other hand, the transmittance of Example 1 is 86% or more even at 300 nm, and it is understood that deep ultraviolet light is transmitted at a high rate. In particular, even at 265 nm, which is the absorption wavelength of DNA, a transmittance of 79% or more is exhibited. Therefore, it can be seen that the deep ultraviolet light sealing material of the present embodiment can be suitably used as a sealing material for deep ultraviolet light emitting elements.

  Moreover, it can be seen from the measurement results of Example 2 that the transmittance is improved by irradiating the polyorganosiloxane with ultraviolet rays. In particular, it can be seen that the transmittance is improved by 10% or more in the range of 200 nm to 270 nm.

2. Sealing material for deep ultraviolet light containing a filler A sealing material for deep ultraviolet light containing a filler according to the present embodiment was produced, and the moldability was examined.

  Starting materials were prepared in the same manner as in Example 1. In addition, calcium fluoride particles (manufactured by Iwatani Corporation) are prepared as fillers, so that the organosiloxane is 50 vol% and the calcium fluoride particles are 50 vol% with respect to the whole deep ultraviolet light sealing material. Calcium fluoride particles were added to.

  Synthesis was performed in the same manner as in Example 1 to obtain a sample of Example 3 having a thickness of 1.0 nm.

  As a deep ultraviolet light sealing material containing no filler, starting materials were prepared in the same manner as in Example 1, and synthesis was performed in the same manner as in Example 1 to obtain a sample of Example 4 having a thickness of 1.0 mm.

  In the sample of Example 4 to which no filler was added, cracks were generated, but in the sample of Example 3, cracks were not generated, and it was found that the addition of filler had an effect of suppressing cracks.

  The deep ultraviolet light sealing material and the deep ultraviolet light emitting device of the present disclosure are suitably used as an ultraviolet light source sealing material and a light emitting device for various uses such as sterilization, water purification, phototherapy, measurement, resin curing, and adhesion. .

DESCRIPTION OF SYMBOLS 11 Deep ultraviolet light-emitting device 12 Board | substrate 12a Upper surface 12b Lower surface 13 Thermal conductive layer 14 Metal layer 15 Deep ultraviolet light emitting element chip 15a Outgoing surface 16 Dam 17 Terminal 18 Conductive pattern 20 Polyorganosiloxane 21 Filler 22 Deep ultraviolet light sealing material 23 Sealing body 23a upper surface

Claims (11)

  A sealing material for deep ultraviolet light containing, as a main component, a polyorganosiloxane having a ratio of carbon-carbon bonds to Si atoms of 5% or less.   The sealing material for deep ultraviolet light according to claim 1, wherein the side chain of the polyorganosiloxane is a methyl group or a trimethylsilyloxy group. The polyorganosiloxane has the following average composition formula (1)

(Wherein R ¹ , R ² and R ³ are each independently a methyl group or a trimethylsilyloxy group, X represents a bond of a branch of the main chain, and m, n and p are m / (m + n + p ) ≧ 0.6 and n + p ≠ 0. A part of the methyl group and the trimethylsilyloxy group may be substituted with a hydroxyl group.)
The sealing material for deep ultraviolet light of Claim 2 shown by these.   The sealing material for deep ultraviolet light according to any one of claims 1 to 3, wherein the polyorganosiloxane has a number average molecular weight of 500 or more and 5000 or less.   5. The deep ultraviolet light sealing according to claim 1, further comprising, as a main component, a filler which is dispersed in the polyorganosiloxane and has a transmittance of 50% or more in a wavelength range of 200 nm or more and 350 nm or less. Stop material.   5. The filler according to claim 1, further comprising, as a main component, a filler that is dispersed in the polyorganosiloxane and is composed of one selected from the group consisting of calcium fluoride, quartz, sapphire, and silicon dioxide. Sealing material for deep ultraviolet light.   The sealing material for deep ultraviolet light according to claim 5 or 6, comprising the filler at a ratio of 40 vol% to 93 vol% with respect to the polyorganosiloxane. At least one deep ultraviolet light emitting element chip disposed on the substrate and having an exit surface;
It is a sealing body which is arrange | positioned on the said board | substrate and consists of the sealing material for deep ultraviolet light in any one of Claim 1-7, Comprising: The said emission surface of the said at least 1 deep ultraviolet light emitting element chip | tip is covered. An arranged sealing body;
Deep ultraviolet light emitting device equipped with. Hydrolyzing the organoalkoxysilane and dehydrating and condensing the decomposition product to form a polymer;
Arranging the polymer so as to cover the deep ultraviolet light emitting element chip;
Forming a sealing body covering the deep ultraviolet light emitting element chip by curing the polymer; and
Including
The said sealing body is a manufacturing method of the deep ultraviolet light-emitting device containing as a main component polyorganosiloxane whose ratio of the carbon-carbon bond number with respect to the number of Si atoms is 5% or less.   The method for manufacturing a deep ultraviolet light-emitting device according to claim 9, wherein the organoalkoxysilane includes tetraethyl orthosilicate, methyltrialkoxysilane, and dimethyldialkoxysilane.   The manufacturing method of the deep ultraviolet light-emitting device of Claim 9 which further includes the process of irradiating the said sealing body with an ultraviolet-ray.

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