JP2007080885A - Optical semiconductor sealing agent, optical semiconductor and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transparent resin which has heat resistance and absorbs no light between a near-ultraviolet light and a visible light, as a sealing agent for semiconductor elements including a white light emitting diode. <P>SOLUTION: The optical semiconductor sealing agent contains a polyimide that is obtained by changing tetracarboxylic acid dianhydride (A), and diamine into imide and an organic solvent (B). In this case, the polyimide is such a polyimide that (i) the tetracarboxylic acid dianhydride having alicyclic structure is 50 mol% or more in the (A) component, or (ii) the diamine having alicyclic structure is 50 mol% or more in the (B) component, or (iii) the tetracarboxylic acid dianhydride having alicyclic structure is 50 mol% or more in the (A) component, and the diamine having alicyclic structure is 50 mol% or more in the (B) component. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an encapsulant for optical semiconductors, an encapsulating resin, an optical semiconductor, and a method for producing the same, containing polyimide having excellent heat resistance, transparency, and low linear thermal expansion coefficient. More specifically, the present invention relates to an optical semiconductor sealing agent containing a solvent-soluble polyimide having an alicyclic structure in the molecule as an essential component and an optical semiconductor sealed with the sealing agent.

In recent years, in the field of light emitting diodes (LEDs), blue or ultraviolet using In _x Ga _y Al _1-xy N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1) type nitride semiconductors. Light-emitting elements are being developed, and the trend toward shorter wavelengths and higher output is progressing. White light can be obtained by combining the light from these light emitting elements with light that has been wavelength-converted by phosphors such as YAG: Ce or RGB phosphors, and is actively used as a backlight for liquid crystals and mobile phones. Has been. In addition, because of its low power consumption and long life, it is highly expected as a substitute for lighting fixtures such as incandescent bulbs and fluorescent lamps, and as a headlight for vehicles. As a sealant for a light emitting diode, an epoxy resin has been conventionally used from the viewpoint of chemical stability and electrical insulation. Generally, bisphenol A diglycidyl ether is cured with methylhexahydrophthalic anhydride, but the main emission peak of light-emitting diodes with shorter wavelengths and higher output is in the region of 365 to 500 nm, Absorption of the aromatic ring in the resin causes deterioration of the resin over time, resulting in a problem that the light emission luminance is remarkably reduced, such as yellowing. Furthermore, high-power light emission has become common due to advances in bonding technology that achieves high brightness, such as double heterojunction and multiple well bonding, and problems such as deterioration due to heat generation and damage to semiconductor chips due to thermal stress cannot be ignored.

  In order to solve these problems, use of a hydrogenated epoxy monomer, an alicyclic epoxy monomer and an acid anhydride (Patent Document 1) has been proposed in place of the bisphenol type epoxy resin. However, in a surface-mount type semiconductor, which has become the mainstream of recent semiconductor mounting methods, it is important to reduce the thickness of the sealing resin, and there are cases where several hundreds to several tens of μm or less are required. In the case of a general epoxy resin, it has been pointed out that when the resin is cured in such a thin film state, the contact area with air becomes large, so that a curing failure occurs due to sublimation and moisture absorption of the acid anhydride. Therefore, it has been proposed to change the curing agent from an acid anhydride to a nonvolatile cationic curing agent (Patent Document 2). However, in general, a cationic curing agent contains an aromatic ring such as an aromatic sulfonium salt, aromatic diazonium salt, or aromatic iodonium salt, and thus tends to be inferior in transparency and yellowing resistance. In addition, a method for improving the curing performance using cyclohexanetricarboxylic acid monoester as a curing agent has been proposed (Patent Document 3). The sealing resin obtained from the curing agent and the hydrogenated epoxy resin has a low glass transition temperature of around 100 ° C. and cannot withstand the heat generated by high-power light emission, and cracks may occur during the cooling cycle in the surface mounting process. There is a problem that lead-free solder heat resistance (240 to 265 ° C.) such as Sn—Ag type is insufficient. Thus, for optical semiconductor sealing including white light-emitting diodes, there is no light absorption from the near ultraviolet region to the visible region, heat resistance, and transparency that has sufficient hardness to protect the semiconductor even on a thin film A sealing resin having a property has been demanded.

JP 2000-196151 A JP 2005-68303 A JP-A-2005-53874

  An object of the present invention is a sealing material for optical semiconductors including white light emitting diodes, which has no light absorption from the near ultraviolet region to the visible region, has heat resistance, and has excellent hardness. An object of the present invention is to provide a sealing agent having the above-mentioned properties suitable for sealing a surface-mount type optical semiconductor, an optical semiconductor sealed with the sealing agent, and a method for manufacturing the same.

In order to solve this problem, intensive studies were conducted and the following findings were obtained.
(1) The polyimide obtained by imidizing a specific tetracarboxylic dianhydride and a specific diamine is excellent in transparency in the range from the near ultraviolet region to the visible region.
(2) Moreover, the said polyimide is excellent in heat resistance, and excellent in hue stability at high temperature.
(3) The polyimide has excellent mechanical strength (surface hardness).
(4) Moreover, the polyimide solution containing the said polyimide and the organic solvent has a viscosity characteristic and a solidification characteristic suitable for the manufacturing process of the semiconductor for surface mounting.
(5) Furthermore, by using together with an epoxy resin, a sealing resin having a particularly low linear thermal expansion coefficient is obtained.

  The present invention has been completed on the basis of such findings, and provides the following inventions.

[Item 1] An optical semiconductor sealing agent containing (A) a polyimide obtained by imidizing tetracarboxylic dianhydride and (B) diamine, and an organic solvent,
(i) the tetracarboxylic dianhydride having an alicyclic structure is 50 mol% or more in the component (A),
(ii) the diamine having an alicyclic structure is 50 mol% or more in the component (B), or
(iii) The tetracarboxylic dianhydride having an alicyclic structure is 50 mol% or more in the component (A), and the diamine having an alicyclic structure is 50 mol% or more in the component (B). is there,
An optical semiconductor sealing agent, which is polyimide.

  [Item 2] The optical semiconductor sealing agent according to Item 1, wherein (A) is 100 mol% of a tetracarboxylic dianhydride having an alicyclic structure.

  CLAIM | ITEM 3 The optical semiconductor sealing agent of claim | item 1 whose (B) is 100 mol% of diamine which has an alicyclic structure.

  [Item 4] The optical semiconductor sealing agent according to any one of Items 1 to 3, wherein (A) is 1,2,4,5-cyclohexanetetracarboxylic dianhydride.

  [Item 5] (B) is from 4,4′-diaminodicyclohexylmethane, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane and 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane. Item 4. The optical semiconductor sealing agent according to any one of Items 1 to 3, which is at least one selected from the group consisting of:

  CLAIM | ITEM 6 The optical-semiconductor sealing agent in any one of claim | item 1-5 containing 100-2,000 weight part of organic solvents with respect to 100 weight part of polyimides.

  [Item 7] The organic solvent is at least one selected from the group consisting of N-methyl-2-pyrrolidone, 1,3-dimethylimidazolidin-2-one, N, N-dimethylacetamide, cresol, and γ-butyrolactone. The optical semiconductor sealing agent in any one of claim | item 1 -6 which is these.

  CLAIM | ITEM 8 Furthermore, the optical semiconductor sealing agent in any one of claim | item 1 -7 containing a fluorescent substance.

  CLAIM | ITEM 9 Furthermore, the optical semiconductor sealing agent in any one of claim | item 1 -8 containing an epoxy resin.

  CLAIM | ITEM 10 The optical semiconductor sealing agent in any one of claim | item 1 -9 whose viscosity in 25 degreeC of optical semiconductor sealing agent is 0.1-30 Pa.s.

  [Item 11] An optical semiconductor sealing resin obtained by drying and solidifying the optical semiconductor sealing agent according to any one of Items 1 to 10.

  [Item 12] The optical semiconductor sealing resin according to Item 11, which is in the form of a layer or a film.

  [Item 13] The optical semiconductor sealing resin according to Item 11 or 12, wherein the Tg of the optical semiconductor sealing resin is 200 to 350 ° C.

  CLAIM | ITEM 14 Optical semiconductor sealing resin in any one of claim | item 11-13 whose 400 nm light transmittance of optical semiconductor sealing resin is 60 to 99.5%.

  CLAIM | ITEM 15 The optical semiconductor provided with the optical semiconductor sealing resin in any one of claim | item 11-14.

  [Item 16] The optical semiconductor according to Item 15, wherein the optical semiconductor is a surface-mount optical semiconductor.

  [Item 17] The optical semiconductor according to Item 15 or 16, wherein the optical semiconductor is a light emitting diode.

  [Item 18] A step of applying the optical semiconductor sealing agent according to any one of Items 1 to 10 on a semiconductor to form a coating film, and the solvent is dried and distilled from the coating film to form a layer or a film. Forming a solidified sealing resin molded body and sealing the semiconductor.

  Since the optical semiconductor sealing agent of the present invention provides a sealing resin excellent in transparency, heat resistance and mechanical strength, it is suitably used as a sealing resin for optical semiconductors and the like. In addition, since it is excellent in yellowing resistance and there is little change in hue at high temperature, the optical semiconductor encapsulated with the optical semiconductor encapsulant of the present invention has little discoloration even after long-term use and has a long life. is doing.

[Polyimide]
The polyimide which concerns on this invention is a polyimide which contains an alicyclic structure in a specific ratio in a molecule | numerator, and is obtained by imidating specific (A) tetracarboxylic dianhydride and specific (B) diamine. be able to.

[(A) component: tetracarboxylic dianhydride]
Examples of the component (A) include alicyclic tetracarboxylic dianhydrides, aliphatic tetracarboxylic dianhydrides, and aromatic tetracarboxylic dianhydrides. Examples of the alicyclic tetracarboxylic dianhydride include C8-30 tetracarboxylic dianhydrides having at least one alicyclic structure in the molecule. The alicyclic structure may be a monocyclic structure, a polycyclic structure, or a condensed ring structure. Specific examples of such alicyclic tetracarboxylic dianhydrides include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 3 -Carboxymethylcyclopentane-1,2,4-tricarboxylic acid dianhydride, 1,2,3,4-cyclohexanetetracarboxylic dianhydride, bicyclo [2.2.1] heptanetetracarboxylic dianhydride, Bicyclo [2.2.1] heptane-5-carboxymethyl-2,3,6-tricarboxylic acid dianhydride, bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetra Carboxylic acid dianhydride, bicyclo [2.2.2] octane-2,3,5,6-tetracarboxylic acid dianhydride, pentacyclo [8.2.1.11 ^4,7 . 0 ^2,9 . 0 ^3,8 ] tetradecane-5,6,11,12-tetracarboxylic dianhydride, 5- (2,5-dioxotetrahydrofuryl) -3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride Bicyclo [2.2.1] heptane-2-carboxymethyl-2,5,6-tricarboxylic acid dianhydride, bicyclo [2.2.2] octane-2-carboxyethyl-2,5,6- Examples thereof include tricarboxylic dianhydride and 3,3 ′, 4,4′-dicyclohexyltetracarboxylic dianhydride. Among these, 1,2,4,5-cyclohexanetetracarboxylic dianhydride is preferable in that the obtained polyimide has excellent heat resistance and transparency. These alicyclic tetracarboxylic dianhydrides can be used alone or in admixture of two or more for the imidization reaction.

  Examples of the aliphatic tetracarboxylic dianhydride include aliphatic tetracarboxylic dianhydrides having 8 to 30 carbon atoms, specifically, 1,2,3,4-butanetetracarboxylic dianhydride, Examples include 1,2,5,6-hexanetetracarboxylic dianhydride. These aliphatic tetracarboxylic dianhydrides may be used alone or in combination of two or more for the imidization reaction.

  Examples of the aromatic tetracarboxylic dianhydride include C 10-30 tetracarboxylic dianhydrides containing at least one aromatic ring in the molecule, specifically, 3, 3 ′, 4, 4′-diphenylsulfonetetracarboxylic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 4,4′-oxydiphthalic dianhydride, pyromellitic dianhydride, 2, 2 ′, 3,3′-benzophenonetetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,2 ′, 3,3′-biphenyltetracarboxylic dianhydride 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) propane dianhydride, 1,1-bis (2,3-dicarboxy Phenyl) Tanni anhydride, 1,2-bis (2,3-dicarboxyphenyl) ethane anhydride, 1,1-bis (3,4-dicarboxyphenyl) ethane anhydride, 1,2-bis (3,4) Dicarboxyphenyl) ethane anhydride, bis (2,3-dicarboxyphenyl) methane anhydride, bis (3,4-dicarboxyphenyl) methane anhydride, 4,4 ′-(p-phenylenedioxy) diphthalic acid Dianhydride, 4,4 '-(m-phenylenedioxy) diphthalic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic acid Dianhydrides, 1,2-ethylenebis (anhydrotrimellitate), 1,4-phenylenebis (anhydrotrimellitate), 1,3,3a, 4,5,9b-hexahydro-5 (te Rahidoro-2,5-dioxo-3-furanyl) naphtho [1,2-c] furan-1,3-dione and the like. Among these, 3,3 ′, 4,4′-diphenylsulfonetetracarboxylic dianhydride, 3,3 from the viewpoint that a polyimide having a high molecular weight is easily obtained and a polyimide having excellent transparency and solvent solubility is obtained. ', 4,4'-Benzophenonetetracarboxylic dianhydride and 4,4'-oxydiphthalic dianhydride are preferred. These aromatic tetracarboxylic dianhydrides can be used alone or in admixture of two or more for the imidization reaction.

  The component (A) can be used alone or in combination of two or more for imidization reaction. From the viewpoint that the resulting polyimide is excellent in transparency and yellowing resistance, It is preferable to subject the cyclic tetracarboxylic dianhydride alone to the imidization reaction. Moreover, when mixing 2 or more types and using for imidation reaction, alicyclic tetracarboxylic dianhydride is 50 mol% or more in all (A) components, Preferably it is 80 mol% or more. It is recommended to be subjected to imidization reaction.

  Further, like the above tetracarboxylic dianhydrides, these tetracarboxylic acids, esters with aliphatic alcohols having 1 to 4 carbon atoms, aryl esters with phenols having 6 to 10 carbon atoms, or acid chlorides, etc. It can use for an imidation reaction with the form.

[(B) component: diamine]
(B) As a component, alicyclic diamine, aliphatic diamine, and aromatic diamine are mentioned. As alicyclic diamine, C4-C30 alicyclic diamine which has at least 1 alicyclic group in a molecule | numerator is mentioned. The alicyclic structure may be a monocyclic structure, a polycyclic structure, or a condensed ring structure. Specific examples of the alicyclic diamine include 4,4′-diaminodicyclohexylmethane, 4,4′-diamino-3,3′-dimethylcyclohexylmethane, 4,4′-diamino-3,3 ′, 5, 5'-tetramethylcyclohexylmethane 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, 2,2-bis (4,4'- Diaminocyclohexyl) propane, 1,3-bisaminomethylcyclohexane, 1,4-bisaminomethylcyclohexane, 2,3-diaminobicyclo [2.2.1] heptane,
2,5-diaminobicyclo [2.2.1] heptane, 2,6-diaminobicyclo [2.2.1] heptane, 2,7-diaminobicyclo [2.2.1] heptane, 2,5-bis (Aminomethyl) -bicyclo [2.2.1] heptane, 2,6-bis (aminomethyl) -bicyclo [2.2.1] heptane, 2,3-bis (aminomethyl) -bicyclo [2.2 .1] heptane, 3 (4), 8 (9) -bis (aminomethyl) -tricyclo [5.2.1.0 ² . 6] A decane etc. are mentioned. Among these, 4,4′-diaminodicyclohexylmethane, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane are preferred because a polyimide having a high molecular weight is easily obtained and a polyimide having excellent transparency and solvent solubility is obtained. 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane is preferred. These alicyclic diamines can be used alone or in admixture of two or more for the imidization reaction.

  Examples of the aliphatic diamine include aliphatic diamines having 2 to 22 carbon atoms. Specific examples thereof include ethylenediamine, 1,3-propanediamine, 1,4-butanediamine, 1,5-hebutanediamine, 1 , 6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,12-dodecanediamine and other alkylene diamines, oxydi (2-aminoethane) And polyoxyalkylenediamines such as oxydi (2-aminopropane) and 2- (2-aminoethoxy) ethoxyaminoethane. These aliphatic diamines can be used for imidization reaction alone or in admixture of two or more.

Examples of aromatic diamines include C6-C30 diamines having at least one aromatic ring in the molecule, and specifically include o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, m-amino. Benzylamine, p-aminobenzylamine, 4,4′-diaminobiphenyl, 4,4′-diaminodiphenylmethane, 1,1-bis (4-aminophenyl) ethane, 1,2-bis (4-aminophenyl) ethane 2,2-bis (4-aminophenyl) propane, bis (4-aminophenyl) sulfide, bis (4-aminophenyl) sulfoxide, bis (4-aminophenyl) sulfone, 3,3′-diaminodiphenyl ether, 4 4'-diaminodiphenyl ether, 3,3'-diaminobenzophenone, 4,4'-diaminobenzo Enone, 1,3-bis (3-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 1,4-bis [1- (4-aminophenyl) -1-methylethyl] benzene, 1,4-bis [4- (3-aminophenoxy) benzoyl] benzene, bis [4- (4-aminophenoxy) phenyl] methane,
1,1-bis [4- (4-aminophenoxy) phenyl] ethane, 1,1-bis [3- (4-aminophenoxy) phenyl] ethane, 1,2-bis [4- (4-aminophenoxy) Phenyl] ethane, 1,2-bis [3- (4-aminophenoxy) phenyl] ethane,
2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [3- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenoxy) -3-methylphenyl] propane, 4,4'-bis (4-aminophenoxy) biphenyl, 4,4'-bis (3-aminophenoxy) biphenyl, 4,4'-bis (3-aminophenoxy) -3 , 3′-methylbiphenyl, bis [4- (4-aminophenoxy) phenyl] sulfide, bis [3- (4-aminophenoxy) phenyl] sulfide, bis [4- (4-aminophenoxy) phenyl] sulfoxide, bis [3- (4-aminophenoxy) phenyl] sulfoxide, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [3- (4-aminophenyl) Enoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) phenyl] ketone, bis [ Examples include 3- (4-aminophenoxy) phenyl] ketone. Among these, 4,4′-diaminodiphenyl ether and 2,2-bis [4- (4-aminophenoxy) phenyl] are preferred because a polyimide having a high molecular weight is easily obtained and a polyimide having excellent solvent solubility is obtained. Propane is preferred. These aromatic diamines can be used alone or in combination of two or more for the imidization reaction.

  The component (B) can be used alone or in combination of two or more for imidation reaction. From the viewpoint that the resulting polyimide is excellent in transparency and yellowing resistance, It is preferable to subject the cyclic diamine alone to the imidization reaction. Moreover, when mixing 2 or more types and using for imidation reaction, it is made into imidation reaction so that alicyclic diamine may be 50 mol% or more in all (B) components, Preferably it is 80 mol% or more. It is recommended to provide.

  Like the diamine, it may be subjected to an imidization reaction in the form of these isocyanate derivatives. Moreover, in order to obtain the polyimide excellent in transparency, you may refine | purify diamine before using for imidation reaction. The method of purification is not particularly limited, and for example, methods such as distillation and recrystallization can be used. The recrystallization solvent is not particularly limited, and examples thereof include hydrocarbons such as octane and nonane, and glycol ethers such as ethylene glycol dimethyl ether and diethylene glycol dimethyl ether.

[Preferable combination of component (A) and component (B)]
Among the above components (A) and (B), a polyimide obtained from the following combination is particularly preferable in terms of excellent transparency.

  Component (A) is 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 3,3 ′, 4,4′-diphenylsulfonetetracarboxylic dianhydride, 3,3 ′, 4,4 ′ -At least one selected from the group consisting of benzophenone tetracarboxylic dianhydride and 4,4'-oxydiphthalic dianhydride, wherein (B) component is 4,4'-diaminocyclohexylmethane, 1,3- Diaminocyclohexane, 1,4-diaminocyclohexane, 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, 4,4'-diaminodiphenyl ether and 2,2-bis [4- (4-aminophenoxy) Combinations with at least one diamine selected from phenyl] propane. However, the component (A) contains 50 mol% or more of 1,2,4,5-cyclohexanetetracarboxylic dianhydride, and / or the component (B) is 4,4′-diaminocyclohexylmethane, Limited to those containing 50 mol% or more of an alicyclic diamine selected from the group consisting of 1,3-diaminocyclohexane, 1,4-diaminocyclohexane and 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane .

  In addition, as a raw material for the imidization reaction, 100 mol% of an alicyclic tetracarboxylic dianhydride is used as the component (A) and / or 100 mol of an alicyclic diamine is used as the component (B). The polyimide obtained by imidization using% tends to be excellent in solvent solubility and transparency.

  Furthermore, the fully alicyclic polyimide obtained by using an alicyclic tetracarboxylic dianhydride as the component (A) and an alicyclic diamine as the component (B) is particularly excellent in transparency and yellowing resistance. This is preferable. In particular, the component (A) is 1,2,4,5-cyclohexanetetracarboxylic dianhydride, and the component (B) is 4,4′-diaminocyclohexylmethane, 1,3-diaminocyclohexane, , 4-diaminocyclohexane or 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane is preferred.

There is no restriction | limiting in particular in the method of imidation reaction, According to a conventionally well-known method, it can carry out.
For example, a two-stage method in which a polycarboxylic acid (polyimide precursor) is prepared by polymerizing tetracarboxylic dianhydride and diamine in an organic solvent at a temperature of less than 100 ° C., and then dehydrating and ring-closing to prepare a polyimide. And a one-step method for directly synthesizing polyimide without preparing polyamic acid. Among these methods, a two-stage method is recommended in that a polyimide having a good hue can be obtained.

  Below, the imidation reaction by a two-stage method is demonstrated. As described above, the two-stage method comprises a polymerization reaction step to polyamic acid, a ring-closing imidization step, and two steps. First, the former polyamic acid polymerization reaction step will be described. After dissolving a diamine in an organic solvent under an inert gas stream such as argon or nitrogen, tetracarboxylic dianhydride is gradually added in a temperature range of -10 ° C to 100 ° C, preferably 40 to 80 ° C. Alternatively, diamine may be gradually added after tetracarboxylic dianhydride is dissolved in an organic solvent. In this case, the molar ratio of (A) tetracarboxylic dianhydride component to (B) diamine component is (A) / (B) = 0.7 in that a polyamic acid having a high degree of polymerization is easily obtained. It is preferable that it is -1.3, and the range of 0.9-1.1 is especially preferable. Moreover, when using together the polyimide which concerns on this invention, and an epoxy resin, the range of (A) / (B) = 0.9-1.3 from the point which is excellent in the hardness of the sealing resin molding obtained. The range of 1.0 to 1.2 is particularly preferable.

  The substrate concentration (total weight of component (A) and component (B) / total weight of component (A), component (B) and organic solvent) is 5 to 40% by weight, preferably 10%. ~ 30% by weight. When the substrate concentration is less than 5% by weight, it is difficult to obtain a polyamic acid having a high degree of polymerization, and the polyimide finally obtained tends to be mechanically fragile. On the other hand, when the substrate concentration exceeds 40% by weight, there is a tendency that polymerization is not completed or a long time is required until the polymerization is completed due to precipitation of a salt insoluble in an organic solvent.

  Examples of the organic solvent include an aprotic polar solvent, a phenol solvent, and a glycol solvent. Specific examples of the aprotic polar solvent include N, N-dimethylacetamide, N, N-dimethylformamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, 1,3-dimethyl-2-imidazolidinone and the like. Amide solvents, lactone solvents such as γ-butyrolactone, phosphorus-containing amide solvents such as hexamethylphosphoric triamide, hexamethylphosphine triamide, sulfur-containing solvents such as dimethyl sulfone, dimethyl sulfoxide, sulfolane, Examples thereof include ketone solvents such as cyclohexanone and methylcyclohexanone.

  Specific examples of the phenol solvent include phenol, o-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4- Examples include xylenol and 3,5-xylenol.

  Specific examples of the glycol solvent include ethylene glycol monomethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether and the like.

  Among the above organic solvents, amide solvents and lactone solvents are preferred in that the generation of insoluble salts is small during the polymerization reaction and polyamic acid having a high degree of polymerization is easily obtained, and particularly N-methyl-2-pyrrolidone, 1,3-dimethylimidazolidin-2-one, N, N-dimethylacetamide, cresol, and γ-butyrolactone are preferred.

  These organic solvents can be used alone or in admixture of two or more for the polymerization reaction.

  The time required for the polymerization reaction step of the polyamic acid varies depending on the types of tetracarboxylic dianhydride, diamine and organic solvent to be used, and their use ratio, but is usually 0.5 to 100 hours.

  Next, it describes about the process of ring-closing imidation of a polyamic acid. The ring-closing imidization step is carried out by subsequent heat-dehydration imidization after the completion of the polymerization reaction step. The water generated when the polyamic acid is dehydrated and closed and imidized causes hydrolysis of the polyamic acid and lowers the degree of polymerization. Therefore, it is preferable to quickly distill out of the reaction system. For this purpose, it is preferable to use an azeotropic solvent in addition to the organic solvent. The azeotropic solvent may be added during the imidization reaction or may be added in advance from the polyamic acid polymerization reaction step. Specific examples of the azeotropic solvent include aromatic hydrocarbons which may be substituted with alkyl groups such as toluene, xylene and ethylbenzene, cyclohexanes which may be substituted with alkyl groups such as cyclohexane, methylcyclohexane and ethylcyclohexane. Is mentioned. These may be commercially available, and examples of the former include Solvesso 100 (manufactured by Exxon Mobil), and examples of the latter include Ricasolve 800 and 900 (manufactured by Shin Nippon Rika). These azeotropic solvents can be used alone or in admixture of two or more. . When using these azeotropic solvents, the amount used is preferably in the range of 5 to 50% by weight in the total organic solvent. The azeotropic solvent may be distilled off under reduced pressure after completion of the ring-closing imidization step.

  Examples of the reaction temperature in the ring-closing imidization step include a range of 120 ° C to 200 ° C, and a range of 160 to 190 ° C is preferable. The polymerization time varies depending on the types of tetracarboxylic dianhydrides, diamines and organic solvents used, and their use ratios, but is usually 0.5 to 20 hours.

  Further, instead of ring-closing imidization by heat dehydration or for the purpose of promoting ring-closing imidization by heat dehydration, a lower fatty acid dianhydride such as acetic anhydride, a tertiary amine such as triethylamine, pyridine, and picoline is added for By performing ring-closing imidization by the method, the polyimide according to the present invention can be obtained.

  The polyimide polymerization solution thus obtained was obtained by using any of the following three polyimides according to the present invention having structural units derived from the component (A) and the component (B) subjected to the imidization reaction for the imidization reaction. This is a polyimide polymerization solution dissolved in an organic solvent.

  (i) The component (A) in which the tetracarboxylic acid component having an alicyclic structure is 50 mol% or more, preferably 80 mol% or more, particularly preferably 100 mol% in the component (A), and the component (B) And polyimide obtained by imidization reaction. In other words, the component (A) comprises (a1) a tetracarboxylic dianhydride having an alicyclic structure and (a2) a tetracarboxylic dianhydride having no alicyclic structure, and the molar ratio thereof is ( a1) / (a2) = 50-100 / 50-0, preferably (a1) / (a2) = 80-100 / 20-0, particularly preferably (a1) / (a2) = 100/0 Polyimide obtained by imidizing carboxylic dianhydride and (B) diamine.

  (ii) Component (A) and component (B) in which the diamine having an alicyclic structure is 50 mol% or more, preferably 80 mol% or more, particularly preferably 100 mol% in component (B) Polyimide obtained by chemical reaction. In other words, the component (B) is composed of (b1) a diamine having an alicyclic structure and (a2) a diamine having no alicyclic structure, and the molar ratio thereof is (b1) / (b2) = 50 to 100 Polyimide obtained by imidizing (B) component which is / 50-0, preferably (b1) / (b2) = 80-100 / 20-0, and (A) component.

  (iii) The tetracarboxylic dianhydride having an alicyclic structure is 50 mol% or more, preferably 80 mol% or more, particularly preferably 100 mol% or more in the component (A), and the component (A), and The polyimide obtained by imidating the (B) component in which the diamine having an alicyclic structure is 50 mol% or more, preferably 80 mol% or more, particularly preferably 100 mol% in the (B) component. In other words, the component (A) comprises (a1) a tetracarboxylic dianhydride having an alicyclic structure and (a2) a tetracarboxylic dianhydride having no alicyclic structure, and the molar ratio thereof is ( a1) / (a2) = 50-100 / 50-0, preferably (a1) / (a2) = 80-100 / 20-0, particularly preferably (a1) a tetracarboxylic dianhydride alone The component (B) is composed of (b1) a diamine having an alicyclic structure and (b2) a diamine having no alicyclic structure, and the molar ratio thereof is (b1) / (b2) = 50 to 100/50. To 0, preferably (b1) / (b2) = 80 to 100/20 to 0, particularly preferably (b1) a polyimide obtained by imidizing the component (B) alone.

  Although there is no restriction | limiting in particular as an acid value of the polyimide which concerns on this invention, When using an epoxy resin together, an acid value is 1 at the point which is excellent in the balance of the heat resistance of the sealing resin obtained, and a linear thermal expansion coefficient. ˜100 mg KOH / g, preferably 2 to 90 mg KOH / g, particularly preferably 3 to 80 mg KOH / g is recommended. This acid value is a value measured by the method described in the Examples section below.

  The intrinsic viscosity of the polyimide according to the present invention is preferably 0.3 to 3.0 dl / g, more preferably 0.4 to 2.5, particularly from the viewpoint of excellent mechanical strength of the obtained optical semiconductor encapsulating resin. Preferably 0.5 to 2.2 is recommended. This intrinsic viscosity is a value measured by the method described in the Examples section below.

The polyimide polymerization solution is a polyimide solution in that state, and can be used as an optical semiconductor sealing agent as it is, and if necessary, undergoes a filtration / defoaming step, or is concentrated / diluted to obtain a viscosity. After the adjustment, it can be used as an optical semiconductor sealing agent. Furthermore, a part or all of the organic solvent used in the imidization reaction is replaced with a low boiling point solvent (for example, aromatic hydrocarbons such as toluene, xylene, solvent naphtha, ketone solvents such as acetone, methyl ethyl ketone), Alternatively, the polyimide according to the present invention is isolated by drying the polyimide polymerization solution or adding a poor solvent (for example, lower alcohols such as methanol and isopropyl alcohol, and acetates such as ethyl acetate and butyl acetate). After that, it is dissolved in a desired organic solvent to prepare a polyimide solution, which can be used as an optical semiconductor sealing agent. Examples of the organic solvent include the same organic solvents as in the imidization reaction. Specific examples thereof include amide solvents such as N, N-dimethylacetamide, N, N-dimethylformamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, 1,3-dimethyl-2-imidazolidinone, Lactone solvents such as γ-butyrolactone, phosphorus-containing amide solvents such as hexamethylphosphoric triamide, hexamethylphosphine triamide, dimethyl sulfone,
Sulfur-containing solvents such as dimethyl sulfoxide and sulfolane, ketone solvents such as cyclohexanone and methylcyclohexanone, phenol, o-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,4-xylenol, 2,5 Phenolic solvents such as xylenol, 2,6-xylenol, 3,4-xylenol, 3,5-xylenol,
Examples thereof include glycol ether solvents such as ethylene glycol monomethyl ether, diethylene glycol dimethyl ether, and triethylene glycol dimethyl ether. The amount of these organic solvents used is preferably 100 to 2,000 parts by weight, particularly preferably 150 to 900 parts by weight, with respect to 100 parts by weight of polyimide.

[Phosphor]
If necessary, a phosphor can be added to the optical semiconductor encapsulant of the present invention. For example, the phosphor has a function of forming white light by absorbing part of blue light emitted from a blue LED element and emitting wavelength-converted yellow light. The phosphor can be uniformly dispersed in the sealing resin by preliminarily dispersing the phosphor in a solution containing polyimide and then applying the phosphor onto the optical semiconductor. Since the density of the phosphor is higher than that of the resin solution, the phosphor tends to settle during coating and drying when manufacturing the optical semiconductor. In order to suppress sedimentation, it is preferable to increase the viscosity of the optical semiconductor sealing agent. The method for increasing the viscosity of the optical semiconductor sealing agent can be easily adjusted by appropriately changing the type and concentration of polyimide. There is no restriction | limiting in particular as fluorescent substance, A conventionally well-known fluorescent substance can be used, For example, rare earth element aluminate, thio gallate, orthosilicate, etc. are illustrated. More specifically, phosphors such as a YAG phosphor, a TAG phosphor, an orthosilicate phosphor, a thiogallate phosphor, and a sulfide phosphor can be mentioned, and YAlO ₃ : Ce, Y ₃ Al ₅ O ₁₂ : Ce, Y ₄ Al ₂ O ₉ : Ce, Y ₂ O ₂ S: Eu, Sr ₅ (PO ₄ ) ₃ Cl: Eu, (SrEu) O.Al ₂ O _{3 and the} like are exemplified. As the particle size of the phosphor, those having a particle size known in this field are used, and the average particle size is preferably 1 to 250 μm, particularly preferably 2 to 50 μm. When these phosphors are used, the addition amount is recommended to be 1 to 80 parts by weight, preferably 5 to 60 parts by weight with respect to 100 parts by weight of polyimide.

[Epoxy resin]
Furthermore, an epoxy resin can be mix | blended with the optical semiconductor sealing agent of this invention. A conventionally well-known epoxy resin can be used as an epoxy resin used by this invention. As the epoxy compound constituting the epoxy resin, an epoxy compound having two or more epoxy groups in one molecule can be preferably used. Among them, it is preferable to use an epoxy resin having an epoxy equivalent of 100 to 10,000, particularly 100 to 3,000. Furthermore, the epoxy resin which does not have an aromatic ring in a molecule | numerator from the point which is excellent in transparency and yellowing resistance is preferable. Examples of such a preferable epoxy resin include diglycidyl ether of hydrogenated bisphenol A, alicyclic epoxy resin, glycidyl ester of alicyclic polycarboxylic acid, and the like. An alicyclic epoxy resin is an epoxy compound having an epoxycycloalkane skeleton in the molecule, specifically,
1-vinyl-3-cyclohexylene dioxide, 3,4-epoxycyclohexylmethyl-3 ′, 4′-epoxycyclohexanecarboxylate, 3,4-epoxy-6-methylcyclohexyl-3,4-epoxy-6-methylcyclohexane Carboxylate, bis (3,4-epoxycyclohexylmethyl) adipate, bis (3,4-epoxy-6-methylcyclohexylhexyl) adipate, tetrakis (3,4-epoxycyclohexylmethyl) butanetetracarboxylate, di (3 4-epoxycyclohexylmethyl) -4,5-epoxytetrahydrophthalate), ethylenebis (3,4-epoxycyclohexanecarboxylate), ethylenebis (3,4-epoxy-6-methylcyclohexanecarboxylate) Limonene dioxide, bis (3,4-epoxycyclohexyl) methane, 2,2-bis (3,4-epoxycyclohexyl) propane, bis (3,4-epoxycyclohexyl), 1,2,5,6-cycloocta Examples include diene dioxide and dicyclopentadiene dioxide. As the glycidyl ester of alicyclic polycarboxylic acid, tetrahydrophthalic acid diglycidyl ester, hexahydrophthalic acid diglycidyl ester, methylhexahydrophthalic acid diglycidyl ester, 1,2,4-cyclohexanetricarboxylic acid triglycidyl ester, Examples include 1,2,4,5-cyclohexanetetracarboxylic acid tetraglycidyl ester and the like.

  When an epoxy resin is used, the amount used is preferably 1 to 100 parts by weight, particularly 5 to 50 parts by weight based on 100 parts by weight of polyimide.

[Epoxy resin curing agent]
When an epoxy resin is blended with the optical semiconductor encapsulant of the present invention, an epoxy resin curing agent can be used. As the epoxy resin curing agent, any epoxy resin can be used without particular limitation as long as the epoxy resin has a curing or curing promoting action. Specific examples of the epoxy resin curing agent include amine compounds and acid anhydride compounds.

  Examples of amine compounds include aliphatic diamines such as ethylenediamine, propylenediamine, hexamethylenediamine, 2,5-dimethylhexamethylenediamine, and trimethylhexamethylenediamine; diethylenetriamine, bis (hexamethylene) triamine, triethylenetetramine, tetraethylenepenta Mine, aliphatic polyamines such as polyoxyalkylenediamine represented by the general formula (4); fats containing aromatic rings such as metaxylylenediamine, valaxylylenediamine, 1,3,5-tris (aminomethyl) benzene Diamines; cycloaliphatic diamines such as diaminodicyclohexylmethane, bis (4-amino-3-methylcyclohexyl) methane, isophoronediamine, mensendiamine, norbornenediamine; phenylenediamine, methyle Aromatic amines such as dianiline, diaminodiphenylsulfone, and metaaminobenzylamine; triethylamine, benzyldimethylamine, tris (dimethylaminomethyl) phenol, triethanolamine, pyridine, picoline, N, N′-dimethylpiperazine, 1,4- Tertiary amines such as diazabicyclo [2,2,2] octane and 1,8-diazabicyclo [5,4,0] undecene; 2-methylimidazole, 2-undecylimidazole, 2-phenylimidazole, 2-ethyl-4 -Imidazol compounds such as methylimidazole, 2-phenyl-4-methylimidazole, 1-cyanoethylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-phenylimidazole; Acid hydrazite, disiamine diamide compounds, melamine compounds, amine adducts obtained by reacting these amine compounds with epoxy resins, urea, isocyanate compounds or acid anhydrides (Ajinomoto Co., “Amicure PN-23”, Amicure “MY” -24 ", manufactured by Fuji Kasei Co., Ltd.," Fujicure FXE "," Fujicure FXR ", etc.," HT-939 "manufactured by Ciba Specialty Chemicals Co., Ltd.), salts of the above amine compounds and polycarboxylic acids (Ajinomoto Co.," Amicure ATU "), a molecular compound of an amine compound and isocyanuric acid, and the like.

  Examples of acid anhydride compounds include aliphatic acid anhydrides such as alkenyl succinic anhydride, polyadipic acid anhydride, polyazeline acid anhydride, polysebacic acid anhydride; tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride Acid, methylhexahydrophthalic anhydride, bicyclo [2,2,1] hept-5-ene-2,3-dicarboxylic anhydride, methylbicyclo [2,2,1] hept-5-ene-2,3 -Dicarboxylic anhydride, bicyclo [2,2,1] heptane-2,3-dicarboxylic anhydride, methylbicyclo [2,2,1] heptane-2,3-dicarboxylic anhydride, 1,2,4 -Cycloaliphatic acid anhydrides such as cyclohexanetricarboxylic acid monoanhydride and 1,2,4,5-cyclohexanetetracarboxylic dianhydride; phthalic anhydride, anhydrous Mellitic acid, pyromellitic anhydride, benzophenone tetracarboxylic acid anhydride, aromatic acid anhydrides such as ethylene glycol bisanhydrotrimellitate are exemplified.

  Among these, alicyclic acid anhydride compounds and imidazole compounds are preferred in that the obtained optical semiconductor encapsulating resin is excellent in transparency and hardness.

  When an epoxy resin curing agent is used, the amount used depends on the type and blending amount of the epoxy resin, but is 0.1 to 200 parts by weight, especially 0.1 to 100 parts by weight of the epoxy resin. 100 parts by weight is preferred.

[Other ingredients]
The optical semiconductor encapsulant of the present invention may further contain various additives for improving the characteristics of the light emitting diode, such as an antioxidant, a hindered amine light stabilizer (HALS), an antistatic agent, and a surfactant, as necessary. Can be blended. A light diffusing agent has a function of dispersing light generated from a semiconductor element in a sealing resin and uniformizing light emission. For example, titanium oxide, aluminum oxide, silica, zeolite, quartz glass, talc, calcium carbonate , Melamine resin, benzoguanamine resin and the like.

[Optical semiconductor encapsulant]
The optical semiconductor encapsulant of the present invention uses the above components (polyimide and organic solvent, and phosphors used as necessary, epoxy resins, curing agents, curing accelerators, other components) at the above-mentioned use ratios, It can be prepared by a known mixing method. When using phosphors, epoxy resins and other components, there are no particular restrictions on the mixing method and order of mixing, and phosphors and epoxy resins can be added and mixed as they are into the polymerization solution after the imidation reaction. They may be added to and dispersed in an organic solvent, or they may be mixed at the time of use.

  The viscosity at 25 ° C. of the photo-semiconductor encapsulant of the present invention is 0.1 to 30 Pa · s from the viewpoint of excellent balance between workability in the coating process and sedimentation property of the phosphor when the phosphor is used. A range of 1 to 20 Pa · s is recommended. The viscosity is a value measured by the method described in the Examples section below.

[Optical semiconductor encapsulating resin]
The optical semiconductor sealing resin of the present invention can be obtained by drying and solidifying the thus obtained optical semiconductor sealing agent of the present invention according to a conventionally known method. For example, the optical semiconductor encapsulant of the present invention is directly applied or filled on the surface of the semiconductor by a known method, or the semiconductor is immersed in the optical semiconductor encapsulant of the present invention, An optical semiconductor sealing resin (that is, an optical semiconductor sealing resin molding) can be obtained by drying and solidifying the coating film or filler. Here, “drying and solidifying” means volatilizing the organic solvent from the optical semiconductor encapsulant and chemically reacting the polyimide and the epoxy resin used as necessary, but in actual operation, It is not strictly distinguished. The conditions for drying and solidification vary depending on the type of optical semiconductor, the method of use, etc., but are usually 70 ° C. to 350 ° C. (preferably 80 to 320 ° C.), 10 to 300 minutes (preferably 30 to 180 minutes). The conditions are exemplified. In drying and solidifying, the temperature is preferably raised stepwise, and it is also preferred to carry out under reduced pressure.

  In this case, the obtained optical semiconductor encapsulating resin is usually in the form of a transparent layer or film. Although the thickness of this layer or film depends on the purpose of use, it is usually recommended to be 10 to 2,000 μm, more preferably 20 to 1,000 μm, particularly 50 to 500 μm. As a preferable method for obtaining the optical semiconductor encapsulating resin molded body having such a layered or film-like thickness, there is a method in which the optical semiconductor encapsulant of the present invention is applied and then dried and solidified. A range of photosemiconductor encapsulants are suitable for this method.

  The optical semiconductor encapsulating resin of the present invention obtained by drying and solidifying is excellent in transparency, heat resistance, mechanical strength, etc., and can be suitably used as an encapsulant for optical semiconductors. For example, the glass transition temperature (Tg) of the optical semiconductor encapsulated molded article of the present invention is preferably 200 to 350 ° C., and particularly preferably 220 to 320 ° C. Tg is a value measured by the method described in the Examples section below.

  The total light transmittance of the optical semiconductor sealing resin of the present invention is preferably 85 to 99.5%, and particularly preferably 90 to 99.5%. Further, the light transmittance at 400 nm is preferably 60 to 99.5%, and particularly 70 to 99.5% is recommended. In addition, these light transmittances are the values measured by the method described in the section of Examples described later.

  The linear thermal expansion coefficient of the optical semiconductor encapsulating resin of the present invention is preferably 10 to 100 ppm, and particularly preferably 20 to 80 ppm. In addition, a linear thermal expansion coefficient is the value measured by the method as described in the term of an after-mentioned Example.

[Optical semiconductor]
The present invention also provides an optical semiconductor provided with an optical semiconductor resin obtained by drying and solidifying the optical semiconductor sealing agent of the present invention. Examples of the optical semiconductor include a wide range,
Specifically, light-emitting elements such as light-emitting diodes (LEDs), semiconductor lasers, organic EL (electro luminescence), and photodiodes, optical couplers, phototransistors, and charge coupled devices (CCDs) are included. Illustrated. These may be a single element or an array composed of a plurality of elements. There is no restriction | limiting in particular in the shape of an optical semiconductor, Any forms, such as a shell type, a lamp | ramp type, and a SMD type (surface mount type), may be sufficient. Among these, the SMD type optical semiconductor which has the optical semiconductor sealing resin of this invention with the form of the layer thru | or film is preferable. In addition, since the polyimide according to the present invention is excellent in transparency in the near-ultraviolet region, it is suitably used for LEDs, semiconductor lasers, and the like, and in particular, emits light having a wavelength of 500 nm or less such as blue LEDs, purple LEDs, and white LEDs. Suitable for emitting LED.

[Optical Semiconductor Manufacturing Method]
As described above, the optical semiconductor encapsulant of the present invention is useful as an encapsulant for surface-mounted optical semiconductors, particularly LEDs. Below, the usage method of the optical-semiconductor sealing agent of this invention in surface mount type LED is demonstrated as an example of the manufacturing method of an optical semiconductor.

  FIG. 1 is a schematic cross-sectional view of a semiconductor of the present invention. A semiconductor element 4 formed on a sapphire substrate 3 is bonded to a glass epoxy substrate 1 in which a positive terminal 2a and a negative terminal 2b of a lead electrode are insert-molded with a die bond resin such as an epoxy resin. Positive and negative electrodes 5a and 5b are provided on the side, and the lead electrodes 2a and 2b are electrically connected to the conductive wires 6 such as gold wires. As a material of the semiconductor element, conventionally known GaAs, GaP, GaAlAs, GaN, InGaN, InGaAlN, or the like can be used.

  An optical semiconductor encapsulant of the present invention is applied on the optical semiconductor by dipping, spraying, spin coating, roll coating, curtain coating, bar coating, screen printing, or the like, and then dried and solidified to form an optical semiconductor. The layer or film 8 of the optical semiconductor sealing resin of the present invention can be formed thereon. In addition, when a phosphor is blended in the optical semiconductor sealing agent, an optical semiconductor resin layer or film 8 in which the phosphor 7 is dispersed can be obtained. Here, “drying and solidifying” means volatilizing the organic solvent from the optical semiconductor encapsulant and chemically reacting the polyimide and the epoxy resin used as necessary, but in actual operation, It is not strictly distinguished. The conditions for drying and solidification vary depending on the type of optical semiconductor, the method of use, etc., but are usually 70 ° C. to 300 ° C. (preferably 80 to 250 ° C.) and 10 to 300 minutes (preferably 30 to 180 minutes). The conditions are exemplified. In drying and solidifying, the temperature is preferably raised stepwise, and it is also preferable to carry out under reduced pressure.

  The layer or film of the optical semiconductor encapsulating resin does not need to be a single layer. For example, the optical semiconductor encapsulant of the present invention containing no phosphor is applied, dried and solidified on a semiconductor element. After that, the optical semiconductor encapsulant of the present invention containing a phosphor is coated, dried and solidified thereon to form a multilayer structure in which the fluorescent particles are dispersed only in the upper layer of the encapsulating resin. . On the other hand, after forming a lower layer of a sealing resin containing a phosphor, a multilayer structure in which a sealing resin not containing a phosphor is formed as an upper layer can also be used.

  The optical semiconductor thus obtained is further soldered onto an electronic circuit formed on the wiring board 9 such as a copper clad laminate. In recent years, Pb-free solder is becoming mainstream in solder, for example, Sn-Ag solder is being used as an alternative. The temperature required for such a soldering process is 260 ° C., and the optical semiconductor sealing resin of the present invention has heat resistance that can withstand such a soldering process.

EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. In the following production examples, examples, and comparative examples, the measuring method of each characteristic is as follows.

[Physical property evaluation of polyimide]
(A) Polyimide concentration Using a TG-DTA apparatus (EXSTAR 6000, TG-DTA 6200, manufactured by Seiko Instruments Inc.), a polyimide solution that is a reaction product after the imidation reaction is completed (100 ml / min). ) The residual weight when the temperature was raised to 400 ° C. at a rate of temperature increase of 5 ° C./min was determined as the polyimide concentration (wt%).

(B) Intrinsic viscosity The polyimide solution, which is a reaction product after the imidation reaction, was diluted with NMP or mixed cresol so that the polyimide concentration was 0.5 g / dl. And measured at 30 ° C. As a control, the flow time of NMP or mixed cresol was measured, and the intrinsic viscosity was calculated from the following formula.
Intrinsic viscosity (dl / g) = ln [(t ₁ −t ₀ ) / t ₀ )] / 0.5

(C) Solution viscosity The polyimide solution which is a reaction product after the imidation reaction was measured at 25 ° C using an E-type viscosity system.
(D) Acid value About 2 g of the polyimide solution, which is the reaction product after the imidation reaction, is precisely weighed and diluted with 50 ml of NMP, and then the acid value is measured according to JIS K 0070-1966. Converted.

[Production Example 1]
In a 5 L four-necked flask equipped with a thermometer, a stirrer, a nitrogen inlet tube, a separator decanter, and a condenser tube, 4,4′-diaminodicyclohexylmethane (hereinafter abbreviated as “HDAM”) in a nitrogen stream 272. After 8 g (1.30 mol) and 2350 g of N-methyl-2-pyrrolidone (hereinafter referred to as “NMP”) were charged and dissolved, 1,2,4,5-cyclohexanetetracarboxylic acid dicarboxylate at 50 ° C. Anhydrous anhydride (hereinafter abbreviated as “HPMDA”) 299.7 g (1.33 mol) was charged as a solid, heated to 120 ° C. and completely dissolved. 280 g of xylene was added as an azeotropic solvent, and the reaction was carried out at 180 ° C. for 5 hours while separating the water azeotroped with xylene with a separating decanter. The temperature was cooled to 100 ° C., the reaction system was reduced to 40 mmHg, and about 30 g of xylene was distilled off and collected to obtain a solution containing polyimide (polyimide A) as an imidization reaction product. The resin concentration, intrinsic viscosity, solution viscosity and acid value of this polyimide A solution are shown in Table 1.

[Production Example 2]
To a 1 L four-necked flask equipped with a thermometer, a stirrer, a nitrogen introduction tube, a separator decanter, and a cooling tube, 2,2-bis [4- (4-aminophenoxy) phenyl] propane (hereinafter, referred to as a nitrogen stream) 49.81 g (0.121 mol) and 420 g of mixed cresol (manufactured by Nacalai Tesque) were charged and dissolved, and then 27.20 g (0.121 mol) of HPMDA was dissolved at 50 ° C. The solution was charged as it was, and heated up to 120 ° C. to be completely dissolved. 60 g of xylene was added as an azeotropic solvent, and the reaction was carried out at 180 ° C. for 5 hours while separating the water azeotroped with xylene with a separating decanter. The temperature was cooled to 100 ° C., the reaction system was reduced to 40 mmHg, and about 40 g of xylene was distilled off and collected to obtain a solution containing polyimide (polyimide B) as an imidization reaction product. The resin concentration, intrinsic viscosity, and solution viscosity of this polyimide B solution are shown in Table 1.

[Production Example 3]
In a 1 L four-necked flask equipped with a thermometer, a stirrer, a nitrogen inlet tube, a separator decanter, and a condenser tube, 25.5 g (0.121 mol) of HDAM and 300 g of solvent NPM were charged and dissolved in a nitrogen stream. At 50 ° C., 43.3 g (0.121 mol) of 3,3 ′, 4,4′-diphenylsulfonetetracarboxylic dianhydride (hereinafter abbreviated as “DSDA”) was charged as a solid, and 120 ° C. The solution was heated to complete dissolution. 90 g of xylene was added as an azeotropic solvent, and the reaction was carried out at 180 ° C. for 5 hours while separating the water azeotroped with xylene with a separating decanter. The temperature was cooled to 100 ° C., the pressure of the reaction system was reduced to 40 mmHg, and about 20 g of xylene was distilled off and collected to obtain a polyimide solution containing polyimide (polyimide C) as an imidization reaction product. Table 1 shows the resin concentration, intrinsic viscosity, solution viscosity, and acid value of this polyimide C solution.

[Production Example 4]
A polyimide solution containing polyimide (polyimide D) as an imidization reaction product was prepared in the same manner as in Production Example 3 except that 49.8 g (0.121 mol) of BAPP was used instead of HDAM and 30 g of xylene was added. Obtained. The resin concentration, solution viscosity, and intrinsic viscosity of this polyimide D solution are shown in Table 1.

[Examples 1 to 4, Comparative Example 1]
<Evaluation of optical semiconductor encapsulating resin>
The optical semiconductor sealing agent which has the composition of Table 2 which consists of the polyimide solution obtained by the said manufacture example or a polyimide solution and an epoxy resin hardening | curing agent was prepared.

<Manufacture and evaluation 1 of optical semiconductor sealing resin>
The optical-semiconductor sealing agent of each Example and the comparative example was apply | coated on the glass substrate, and it casted with the glass rod which wound the tape seal | sticker so that it might become 0.8 mm of gap length. This substrate was dried under reduced pressure at 80 ° C. for 1 hour and further at 180 ° C. for 1 hour, and after cooling, the dried film of the optical semiconductor sealing agent was peeled off from the glass substrate and fixed with a stainless steel frame, and the reduced pressure was reduced to 320 The film 1 of optical semiconductor sealing resin with a film thickness of 100 micrometers was obtained by making it dry at 1 degreeC for 1 hour. Using the obtained film A, total light transmittance, 400 nm light transmittance, yellowness (YI), and hardness were measured under the following conditions. The results are shown in Table 2.

<Manufacture and evaluation of optical semiconductor encapsulating resin 2>
The optical semiconductor sealing agent of each Example and Comparative Example was applied on a glass substrate and cast with a glass rod wound with a tape seal so that the gap length was 0.4 mm. This substrate was dried under reduced pressure at 80 ° C. for 1 hour and further at 180 ° C. for 1 hour, and after cooling, the dried film of the optical semiconductor sealing agent was peeled off from the glass substrate and fixed with a stainless steel frame, and the reduced pressure was reduced to 320 The film 2 of optical semiconductor sealing resin with a film thickness of 50 micrometers was obtained by making it dry at 1 degreeC for 1 hour. Using the obtained film B, the glass transition temperature and the linear thermal expansion coefficient were measured under the following conditions. The results are shown in Table 2.

[Comparative Example 2]
Hexahydrophthalic anhydride (manufactured by Shinmoto Rika, trade name “Licacid MH-700”, with respect to 100 parts by weight of bisphenol A type epoxy resin (epoxy equivalent 205, hereinafter abbreviated as “epoxy resin F”), Hereinafter, it is abbreviated as “curing agent G.” 82 parts by weight and 1.8 parts of 2-ethyl-4-methylimidazole (hereinafter abbreviated as “accelerator H”) are mixed and further stirred at 120 ° C. for 2 hours. Curing was performed at 150 ° C. for 3 hours to obtain a cured product having a thickness of 100 μm. The obtained cured product was measured for total light transmittance, 400 nm light transmittance, yellowness (YI), hardness, glass transition temperature, and linear thermal expansion coefficient.

(E) Total light transmittance A 30 mm × 30 mm measurement sample was cut out from the film 1 or cured product obtained in each example or comparative example, and a haze meter (HAZE GARD II, manufactured by Toyo Seiki Co., Ltd.) was used. JIS K-7361 The total light transmittance was measured according to 1.

(F) 400 nm light transmittance From a film 1 or cured product obtained in each example or comparative example, a 30 mm × 30 mm measurement sample is cut out and transmitted using a spectrophotometer (Shimadzu UV-2100, using an integrating sphere). The rate was measured. Moreover, after heat-processing in air at 150 degreeC for 24 hours, it measured again.

(G) Yellowness: YI
From the film 1 obtained in each Example or Comparative Example, YI was measured according to JIS K-7105 as a measurement sample of 30 mm × 30 mm. Moreover, after heat-processing in air at 150 degreeC for 24 hours, it measured again.

(H) Hardness (pencil scratch value)
From the film 1 or cured product obtained in each example or comparative example, the hardness was measured as a measurement sample according to JIS K-7105-1990.

(I) Glass transition temperature (Tg)
From the film 2 or cured product obtained in each Example or Comparative Example, a 20 mm × 5 mm measurement sample was cut out, and using a dynamic viscoelasticity measuring machine (Rheogel-E4000), in a tension mode with a sine wave at a frequency of 10 Hz, It calculated | required from the loss peak (tan-delta) in the temperature increase rate of 5 degree-C / min.

(J) Linear thermal expansion coefficient A 15 mm × 5 mm measurement sample is cut out from the film 2 or cured product obtained in each example or comparative example, and the tensile mode load is 10 g using TMA-4000 (manufactured by MacScience). The linear thermal expansion coefficient was determined as an average value of elongation in the range of 100 ° C to 200 ° C.

  As is apparent from Table 2, the aromatic polyimide film (Comparative Example 1) is not suitable as an optical semiconductor sealing agent because of its low transparency and high YI. In addition, the conventional epoxy resin (Comparative Example 2) has low hardness, low total light transmittance, 400 nm light transmittance after heat treatment, and Tg, and is clearly inferior in heat resistance and yellowing resistance. On the other hand, the optical semiconductor sealing resin obtained from the optical semiconductor sealing agent containing the polyimide having the alicyclic structure of the present invention has sufficient hardness, and has high Tg, high transparency, and yellow resistance. It is clear that it has excellent properties for all modifications and is excellent as an optical semiconductor sealing resin.

  ADVANTAGE OF THE INVENTION According to this invention, the optical semiconductor sealing agent which can form the sealing film excellent in heat resistance, transparency, and mechanical strength can be provided. The optical semiconductor encapsulant makes use of the above-described excellent characteristics and is industrially extremely useful as an optical semiconductor material, and is particularly useful as an encapsulant for surface-mounted white LEDs.

Schematic cross-sectional view of a surface-mounted light-emitting diode

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Glass epoxy board | substrate 2a, b ... Positive / negative lead electrode 3 ... Sapphire substrate 4 ... Optical semiconductor element 5a, b ... Positive / negative electrode 6 ... Wire 7 ... Phosphor 8 ..Sealing resin layer or film 9... Wiring substrate 10... Solder

Claims (18)

(A) A polyimide obtained by imidizing tetracarboxylic dianhydride and (B) diamine, and an optical semiconductor sealing agent containing an organic solvent,
(i) the tetracarboxylic dianhydride having an alicyclic structure is 50 mol% or more in the component (A),
(ii) the diamine having an alicyclic structure is 50 mol% or more in the component (B), or
(iii) The tetracarboxylic dianhydride having an alicyclic structure is 50 mol% or more in the component (A), and the diamine having an alicyclic structure is 50 mol% or more in the component (B). is there,
An optical semiconductor sealing agent, which is polyimide.   The optical semiconductor sealing agent according to claim 1, wherein (A) is 100 mol% of tetracarboxylic dianhydride having an alicyclic structure.   The optical semiconductor sealing agent according to claim 1, wherein (B) is 100 mol% of a diamine having an alicyclic structure.   The optical semiconductor sealing agent according to claim 1, wherein (A) is 1,2,4,5-cyclohexanetetracarboxylic dianhydride.   (B) is selected from the group consisting of 4,4′-diaminodicyclohexylmethane, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane and 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane The optical-semiconductor sealing agent in any one of Claims 1-3 which is at least 1 type selected.   The optical-semiconductor sealing agent in any one of Claims 1-5 containing 100-2,000 weight part of organic solvents with respect to 100 weight part of polyimides.   The organic solvent is at least one selected from the group consisting of N-methyl-2-pyrrolidone, 1,3-dimethylimidazolidin-2-one, N, N-dimethylacetamide, cresol, and γ-butyrolactone. The optical-semiconductor sealing agent in any one of 1-6.   Furthermore, the optical-semiconductor sealing agent in any one of Claims 1-7 containing fluorescent substance.   Furthermore, the optical-semiconductor sealing agent in any one of Claims 1-8 containing an epoxy resin.   The optical semiconductor sealing agent according to any one of claims 1 to 9, wherein the optical semiconductor sealing agent has a viscosity of 0.1 to 30 Pa · s at 25 ° C.   The optical semiconductor sealing resin obtained by drying and solidifying the optical semiconductor sealing agent in any one of Claims 1-10.   The optical semiconductor sealing resin according to claim 11, which is in a layered or film-like form.   The optical semiconductor sealing resin according to claim 11 or 12, wherein Tg of the optical semiconductor sealing resin is 200 to 350 ° C.   The optical semiconductor sealing resin according to any one of claims 11 to 13, wherein the optical semiconductor sealing resin has a light transmittance of 400 nm of 60 to 99.5%.   The optical semiconductor provided with the optical semiconductor sealing resin in any one of Claims 11-14.   The optical semiconductor according to claim 15, wherein the optical semiconductor is a surface-mount optical semiconductor.   The optical semiconductor according to claim 15 or 16, wherein the optical semiconductor is a light emitting diode. A step of applying the optical semiconductor encapsulant according to any one of claims 1 to 10 on a semiconductor to form a coating film, and the solvent is dried and distilled from the coating film to solidify into a layer or a film. Forming an encapsulating resin molding and encapsulating the semiconductor.

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