JP4453008B2 - Thermosetting resin composition for optical semiconductor encapsulation, cured product thereof and optical semiconductor - Google Patents

Description

  The present invention relates to a thermosetting resin composition for sealing an optical semiconductor, a cured product thereof, and an optical semiconductor. More specifically, the present invention relates to a thermosetting resin composition for sealing an optical semiconductor, which is suitable for an optical semiconductor sealing material and provides a cured product having excellent transparency, light resistance, and heat resistance, the cured product, and the optical semiconductor.

A light-emitting diode (hereinafter abbreviated as an LED), which is one of optical semiconductors, is used in various fields as a light source with low heat generation, long life, and low power consumption.
In recent years, LEDs emitting short-wavelength light such as blue light and near ultraviolet light have been developed, and white light can be easily obtained by combining with yellow phosphor. As a result, the applications of LEDs have expanded significantly, but on the other hand, sealing materials used for the purpose of protecting light-emitting elements have higher light resistance, that is, they do not deteriorate even when irradiated with high-energy light for a long time. Characteristics have been required.
Further, as miniaturization and increase in current have progressed as a result of improvements in light emitting elements, the requirement for heat resistance that does not cause coloration even for long-time heat generation has become stricter.
Conventionally, epoxy resin has been mainly used as a sealing material for red and green LEDs. A cured epoxy resin obtained from an acid anhydride and an epoxy compound is inexpensive and excellent in transparency, electrical insulation, moisture resistance, adhesion, and the like. However, when an epoxy resin is used as a sealing material for a white LED made of a blue light emitting element, there arises a problem that it is deteriorated and colored by being irradiated with light having a short wavelength for a long time. If the resin of the sealing material is colored, the light extracted from the LED is significantly attenuated even if the light emitting element itself emits sufficient light, and as a result, the life of the LED is shortened. Similar coloring is also caused by heat generated when the LED is lit for a long time.
Suppressing the deterioration of the sealing material due to such light and heat is an important issue in the further spread of LEDs. Various proposals, such as an epoxy resin composition (patent document 1), are made with respect to such a subject.

JP 2003-160640 A

However, the invention described in the above-mentioned Patent Document 1 has a practical problem in heat resistance and the like because the glass transition temperature is not so high as about 140 ° C. as shown in the Examples.
The present invention has been made in view of the above-described problems, and provides a thermosetting resin composition for optical semiconductor encapsulation that provides a cured product excellent in transparency, light resistance and heat resistance, the cured product, and an optical semiconductor. To do.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a mixed monomer of acrylic acid and / or methacrylic acid and acrylic acid ester and / or methacrylic acid ester (alkyl acrylate and / or alkyl methacrylate). By using a resin composition in which a saturated acrylic polymer having an epoxy group in the side chain is dissolved and a radical polymerization initiator and an antioxidant are added, the thermosetting property is excellent in transparency, light resistance and heat resistance. The present inventors have found that a resin composition can be easily obtained and have completed the present invention.
That is, this invention relates to the thermosetting resin composition for optical semiconductor sealing containing [1] the following (A)-(D) component.
(A) Saturated acrylic polymer having an epoxy group in the side chain (B) Mixed monomer having the following components (b1) and (b2) as essential components (b1) Acrylic acid and / or methacrylic acid (b2) Acrylic Acid ester and / or methacrylic acid ester (C) Radical polymerization initiator (D) Antioxidant In addition, the present invention provides [2] an acrylic polymer (A) having an epoxy group and a copolymerizable unsaturated bond. In the above [1], which is a copolymer comprising 5 to 50% by weight of monomer, 50 to 95% by weight of methyl methacrylate, and 0 to 45% by weight of other acrylic acid ester and / or methacrylic acid ester copolymerizable therewith It is related with the thermosetting resin composition for optical semiconductor sealing of description.
[3] The thermosetting for optical semiconductor encapsulation according to [1] or [2], wherein the weight average molecular weight of the acrylic polymer (A) is 5,000 to 200,000. The present invention relates to a resin composition.
Moreover, this invention is [4] When the total compounding quantity of an acrylic polymer (A) and a mixed monomer (B) is 100 weight part, the compounding quantity of an acrylic polymer (A) is 20-60. Parts by weight, the amount of the mixed monomer (B) is 40 to 80 parts by weight, the amount of the antioxidant (D) is 0.1 to 1.2 parts by weight, and the amount of the radical polymerization initiator (C) Is 0.1 to 1% by weight with respect to the mixed monomer (B), and the blending amount of acrylic acid and / or methacrylic acid (b1) per mole of epoxy group contained in the acrylic polymer (A) It is 1.0-1.2 mol, It is related with the thermosetting resin composition for optical semiconductor sealing in any one of Claim 1 thru | or 3.
The present invention also provides [5] For optical semiconductor encapsulation according to any one of [1] to [4] above, wherein the antioxidant (D) is pentaerythritol diphosphite and / or alkyldiaryl phosphite. The present invention relates to a thermosetting resin composition.
Moreover, this invention relates to the hardened | cured material obtained by hardening the thermosetting resin composition for optical semiconductor sealing in any one of [6] said [1] thru | or said [5].
Furthermore, the present invention relates to [7] an optical semiconductor encapsulated with the cured product described in [6] above.

  The thermosetting resin composition for optical semiconductor sealing of the present invention is suitable for an optical semiconductor sealing material, and can give a cured product having excellent transparency, light resistance and heat resistance.

Hereinafter, the present invention will be described in detail.
The present invention is a thermosetting resin composition for optical semiconductor encapsulation containing the following components (A) to (D).
(A) Saturated acrylic polymer having an epoxy group in the side chain (B) Mixed monomer having the following components (b1) and (b2) as essential components (b1) Acrylic acid and / or methacrylic acid (b2) Acrylic Acid ester and / or methacrylate ester (C) Radical polymerization initiator (D) Antioxidant The component (A) in the present invention is a saturated acrylic polymer having an epoxy group in the side chain, specifically, , A copolymer of an epoxy group and a monomer having a copolymerizable unsaturated bond, and an acrylate ester and / or methacrylic acid ester is preferable, and the copolymer does not contain an unsaturated bond such as an aromatic ring. There is. When the unsaturated bond is contained in the component (A), the light resistance and heat resistance of the cured product are lowered.
There is no restriction | limiting in particular in the method for manufacturing the saturated acrylic polymer which has an epoxy group in the side chain of (A) component, A well-known polymerization method can be applied. For example, any method such as a suspension polymerization method, a bulk polymerization method, an emulsion polymerization method, and a solution polymerization method may be used.

Examples of the monomer having an epoxy group and a copolymerizable unsaturated bond used as the component (A) include unsaturated glycidyl esters such as glycidyl acrylate and glycidyl methacrylate, and unsaturated glycidyl ethers such as allyl glycidyl ether. These can be used alone or in combination of two or more.
These blending amounts are preferably 5 to 50% by weight, and more preferably 15 to 40% by weight, based on the total amount of monomers used for the component (A). When the blending amount is less than 5% by weight, the crosslinking reaction point is insufficient when the thermosetting resin composition is prepared, and the cured product may not be sufficiently cured or sufficient strength may not be obtained. Moreover, when a compounding quantity exceeds 50 weight%, there exists a possibility that the hardened | cured material obtained when it is set as a thermosetting resin composition may become weak.

(A) As acrylic ester used for component, acrylic acid chain alkyl ester such as n-butyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, dicyclopentanyl acrylate, dicyclopentanyloxyethyl acrylate, etc. And polyfunctional acrylic acid esters such as acrylic acid cyclic alkyl ester, ethylene glycol diacrylate, and trimethylolpropane triacrylate.
Further, as the methacrylic acid ester used for the component (A), methacrylic acid chain alkyl ester such as methyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, dicyclopentanyl methacrylate, dicyclopentanyloxyethyl Examples include methacrylic acid cyclic alkyl esters such as methacrylate, and polyfunctional methacrylic acid esters such as ethylene glycol dimethacrylate and trimethylolpropane trimethacrylate.
These acrylic acid esters and methacrylic acid esters can be used alone or in combination of two or more.

The blending amount of these acrylic acid ester and methacrylic acid ester is the amount obtained by subtracting the blending amount of the monomer having an epoxy group and a copolymerizable unsaturated bond, that is, 50% of the whole monomer used for the component (A). In order to ensure sufficient transparency and strength for practical use with respect to the cured product obtained when the thermosetting resin composition for sealing an optical semiconductor is used, at least 50% by weight or more is methyl methacrylate. It is preferable that it contains.
As the component (A), 5 to 50% by weight of a monomer having an epoxy group and a copolymerizable unsaturated bond, 50 to 95% by weight of methyl methacrylate and other acrylic acid ester and / or methacrylic acid copolymerizable therewith A copolymer consisting of 0 to 45% by weight of ester is particularly preferred.

The weight average molecular weight of the (A) component acrylic polymer is preferably 5,000 to 200,000, and more preferably 10,000 to 100,000. When the weight average molecular weight is less than 5,000, shrinkage at the time of curing of a cured product obtained when a thermosetting resin composition is obtained may cause sink or cracking. Moreover, when a weight average molecular weight exceeds 200,000, when setting it as a thermosetting resin composition, it becomes difficult to mix with other components uniformly, and there exists a possibility that handling may become difficult or transparency may be lost.
The method for adjusting the weight average molecular weight of the acrylic polymer of the component (A) is not particularly limited, and a known method can be applied.
In the present invention, the weight average molecular weight is a value measured by GPC (gel permeation chromatography) and converted to standard polystyrene.

  In producing the thermosetting resin composition in the present invention, the blending amount of the component (A) is 20 to 60 parts by weight with respect to a total of 100 parts by weight of the component (A) and the component (B). Preferably, the amount is 30 to 50 parts by weight. When the blending amount is less than 20 parts by weight, shrinkage at the time of curing of the resulting cured product is increased, and there is a risk that sink marks or cracks are likely to occur. Moreover, when a compounding quantity exceeds 60 weight part, it will become difficult to mix with another component uniformly, and there exists a possibility that handling may become difficult or transparency may be lost.

The component (B) used in the present invention is a mixed monomer containing acrylic acid and / or methacrylic acid (b1) and an acrylic ester and / or methacrylic ester (b2) as essential components.
The (b1) component acrylic acid and / or methacrylic acid reacts with the epoxy group contained in the component (A) when the thermosetting resin composition for optical semiconductor encapsulation in the present invention is heated and cured. Used to form a crosslinked structure. As the component (b1), either acrylic acid or methacrylic acid, or a mixture of both in any ratio can be used.
(B1) The compounding quantity of component is 1.0-1.2 mol per mol of epoxy groups contained in the acrylic polymer (A) used in the thermosetting resin composition for optical semiconductor encapsulation in the present invention. It is preferable to use 1.0 to 1.05 mol. When the blending amount is less than 1.0 mol, the epoxy group in the component (A) is theoretically not completely consumed. On the other hand, if the blending amount exceeds 1.2 mol, the amount of carboxyl groups remaining in the cured product obtained when the thermosetting resin composition for optical semiconductor sealing is increased, resulting in water absorption. May increase the performance of the optical semiconductor element or the like to be sealed.
The (b2) component acrylic acid ester and / or methacrylic acid ester is a single compound arbitrarily selected from the same range as the acrylic acid ester and / or methacrylic acid ester used in the production of the component (A). Or it is a mixture of two or more. Of these, chain alkyl esters and cyclic alkyl esters of acrylic acid or methacrylic acid are preferable, chain alkyl esters are more preferable, and methyl methacrylate is particularly preferable.
Monomers other than the acrylic acid ester and / or methacrylic acid ester of component (b2) may be used, but acrylic acid and / or methacrylic acid (b1) and acrylic acid ester and / or methacrylic acid ester (b2) A mixed monomer consisting of
In producing the thermosetting resin composition in the present invention, the blending amount of the component (B) is determined by the blending amount of the component (A), and the sum of the component (A) and the component (B) is 100. It is preferable to set it as 40-80 weight part with respect to a weight part, and it is more preferable to set it as 50-70 weight part.

The radical polymerization initiator of the component (C) used in the present invention is not particularly limited as long as it can generate radicals by heating and polymerize the above monomers. For example, lauroyl peroxide, benzoyl peroxide, Organic peroxides such as bis (t-butylperoxy) trimethylcyclohexane and t-butylperoxyisopropyl carbonate, azo such as 2,2′-azobisisobutyronitrile and 1,1′-azobiscyclohexanecarbonitrile A compound or the like can be used. These can be used alone or in combination of two or more.
In producing the thermosetting resin composition in the present invention, the amount of the component (C) is preferably 0.1 to 1% by weight with respect to the component (B), preferably 0.2 to 0.6. It is more preferable to set the weight%. There exists a possibility that the thermosetting resin composition for optical semiconductor sealing may not fully harden | cure that a compounding quantity is less than 0.1 weight%. On the other hand, if the blending amount exceeds 1% by weight, cracks are likely to occur when heated and cured, and the strength of the resulting cured product may be insufficient.

As the antioxidant of the component (D) used in the present invention, it is preferable to use either pentaerythritol diphosphite or alkyldiaryl phosphite, or a mixture of both in any ratio.
As the pentaerythritol diphosphite used for the component (D), dialkylpentaerythritol diphosphites such as diethyl pentaerythritol diphosphite, distearyl pentaerythritol diphosphite, dicyclohexyl pentaerythritol diphosphite, bis (nonylphenyl) penta Diarylpenta such as erythritol diphosphite, bis (2,4-di-t-butylphenyl) pentaerythritol diphosphite, bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite Examples include erythritol diphosphite.

Examples of the alkyl diaryl phosphite used for the component (D) include diphenyl isooctyl phosphite and diphenyl decyl phosphite.
These pentaerythritol diphosphites and alkyldiaryl phosphites can be used alone or in combination of two or more.
In producing the thermosetting resin composition in the present invention, the blending amount of the component (D) is 0.1 to 1.2 parts by weight with respect to 100 parts by weight of the total of the components (A) and (B). It is preferable to be 0.3 to 0.7 parts by weight. If the blending amount is less than 0.1 parts by weight, sufficient light resistance and heat resistance may not be obtained when a cured product is obtained. Moreover, when a compounding quantity exceeds 1.2 weight part, the improvement of an effect will not be seen.

The thermosetting resin composition for sealing an optical semiconductor of the present invention can be obtained by mixing and uniformly dissolving the above components (A) to (D), but the production method is not particularly limited, and is publicly known. The method can be applied.
When producing the thermosetting resin composition in the present invention, in addition to the above components (A) to (D), various additives are added depending on the purpose within a range that does not impair the properties of the resulting cured product. Can do. As an additive, for example, an antioxidant for further improving the light resistance and heat resistance of a cured product, a chain transfer agent for controlling a radical polymerization reaction in curing, and generally used in a curing reaction of an epoxy resin. Curing accelerators, fillers for improving the mechanical properties, adhesiveness, and handling properties of cured products, plasticizers, stress reducing agents, mold release agents, coupling agents, antifoaming agents, thixotropic agents, dyes , Light scattering agents, ultraviolet absorbers and the like.
By curing the thermosetting resin composition in the present invention by heating, a cured product suitable for an optical semiconductor sealing material can be obtained, but the production method is not particularly limited, and a known method is applied. be able to.
The cured product of the present invention is excellent in all of heat resistance, transparency, and light resistance. The optical semiconductor of the present invention is a light-emitting diode element, a photodiode element or the like sealed with the cured product, and in particular, as a white light-emitting diode in which the property requirements of the sealing material are severe, heat resistance and transparency It is excellent in both light resistance.

Hereinafter, the present invention will be described more specifically with reference to examples.
[Preparation of acrylic polymer (A)]
(1) To a mixture of 442.8 g of methyl methacrylate and 157.2 g of glycidyl methacrylate, 3.6 g of lauroyl peroxide (Perroyl L: manufactured by NOF Corporation) and n-octyl mercaptan (thiocarcoal 08: manufactured by Kao Corporation) 9. 0 g was added and dissolved uniformly, heated at 65 ° C. for 6 hours, and then heated at 120 ° C. for 2 hours to obtain an acrylic polymer (I). The weight average molecular weight was about 22,800.
(2) To a mixture of 412.8 g of methyl methacrylate, 30.0 g of dicyclopentanyl acrylate (FA-513A: manufactured by Hitachi Chemical Co., Ltd.) and 157.2 g of glycidyl methacrylate, lauroyl peroxide (Parroyl L: NOF Corporation) 3.6 g) and n-octyl mercaptan (thiocalcol 08: manufactured by Kao Corporation) 4.8 g were added and dissolved uniformly, heated at 65 ° C. for 6 hours, and then heated at 120 ° C. for 2 hours to obtain an acrylic polymer. (II) was obtained. The weight average molecular weight was about 48,200.
In addition, in a present Example, the measurement conditions (gel permeation chromatography method) of a weight average molecular weight are as follows.
Measuring device Hitachi, Ltd., Column Gel Pack GL-A100M (Hitachi Chemical Industry Co., Ltd., two in series), eluent tetrahydrofuran (flow rate 1.0ml), detector RI (Shodex SE-61), standard Polystyrene PS706

Example 1
40 g of acrylic polymer (I), 0.24 g of lauroyl peroxide (Perroyl L: manufactured by NOF Corporation), diphenyldecyl phosphite (Adeka Stub 135A: manufactured by Asahi Denka Kogyo Co., Ltd.) as the alkyl diaryl phosphite of component (D) ) 0.5 g, 0.1 g of hindered phenol antioxidant (ADK STAB AO-60: manufactured by Asahi Denka Kogyo Co., Ltd.), 5.32 g of acrylic acid, 54.67 g of methyl methacrylate are mixed, and at room temperature (25 ° C.). Stir for 24 hours to dissolve uniformly. Nitrogen gas was bubbled into the resulting thermosetting resin composition for sealing an optical semiconductor for 3 minutes, and then immediately poured into a mold and sealed, and sealed at 60 ° C. for 9 hours, 120 ° C. for 3 hours, and 180 ° C. for 5 hours. In this order, they were heated and cured to obtain a cured product having a thickness of about 1 mm.

(Example 2)
40 g of acrylic polymer (I), 0.24 g of lauroyl peroxide (Perroyl L: manufactured by NOF Corporation), bis (2,6-di-t-butyl-4) as pentaerythritol diphosphite of component (D) -Methylphenyl) pentaerythritol diphosphite (ADK STAB PEP-36: manufactured by Asahi Denka Kogyo Co., Ltd.) 0.7 g, acrylic acid 5.32 g, methyl methacrylate 54.67 g were mixed and stirred at room temperature for 24 hours to be uniform. Dissolved. Thereafter, a cured product was obtained in the same manner as in Example 1.

(Example 3)
Acrylic polymer (II) 40 g, lauroyl peroxide (Perroyl L: manufactured by NOF Corporation) 0.24 g, diphenyldecyl phosphite (ADK STAB 135A: manufactured by Asahi Denka Kogyo Co., Ltd.) 0.5 g, hindered phenol-based oxidation 0.1 g of an inhibitor (ADK STAB AO-60: manufactured by Asahi Denka Kogyo Co., Ltd.), 5.32 g of acrylic acid, and 54.67 g of methyl methacrylate were mixed, and stirred at room temperature for 24 hours to be uniformly dissolved. Thereafter, a cured product was obtained in the same manner as in Example 1.

(Comparative Example 1)
Acrylic polymer (I) 40 g, lauroyl peroxide (Perroyl L: manufactured by Nippon Oil & Fats Co., Ltd.) 0.24 g, acrylic acid 5.32 g, methyl methacrylate 54.67 g were mixed and stirred at room temperature for 24 hours to be uniform. Dissolved. Thereafter, a cured product was obtained in the same manner as in Example 1.

Cracks, transmittance, heat resistance and light resistance of the cured products obtained in Examples 1 to 3 and Comparative Example 1 were evaluated as follows, and the results are shown in Table 1. The characteristic evaluation method in Table 1 is as follows.
-Cracks: The presence or absence of cracks in the cured product was confirmed visually, and evaluated as none or many.
-380 nm transmittance | permeability: The transmittance | permeability in 380 nm of hardened | cured material was measured using the spectrophotometer (JASCO Corporation V-570).
Heat resistance: After heating the cured product at 250 ° C. for 3 hours, the yellowness index (YI) was measured using a color difference measuring device (COH-300A manufactured by Nippon Denshoku Industries Co., Ltd.) to examine the degree of coloring. .
The yellowing degree (YI) indicating yellowishness was determined from the equation (1) by determining the tristimulus value XYZ in the case of the standard light C using the measured transmission spectrum.

-Light resistance: The cured product is irradiated with ultraviolet rays (350 to 410 nm) using an ultraviolet carbon arc lamp for 300 hours, and then a yellowness index using a color difference measuring device (Nippon Denshoku Industries Co., Ltd. COH-300A). (YI) was measured and the degree of coloring was examined. Moreover, the transmittance | permeability in 380 nm was measured using the spectrophotometer (JASCO Corporation V-570).

As shown in Table 1, the thermosetting resin composition for optical semiconductor encapsulation of the present invention gives a cured product excellent in transparency, light resistance and heat resistance. On the other hand, if the antioxidant of the component (D) of Comparative Example 1 is not used, the transparency, light resistance and heat resistance are all poor.

Claims (7)

The thermosetting resin composition for optical semiconductor sealing containing the following (A)-(D) component.
(A) Saturated acrylic polymer having an epoxy group in the side chain (B) Mixed monomer having the following components (b1) and (b2) as essential components (b1) Acrylic acid and / or methacrylic acid (b2) Acrylic Acid ester and / or methacrylic acid ester (C) radical polymerization initiator (D) antioxidant Acrylic polymer (A) is a monomer having an epoxy group and a copolymerizable unsaturated bond, 5 to 50% by weight, methyl methacrylate 50 to 95% by weight and other acrylates copolymerizable therewith and / or The thermosetting resin composition for optical semiconductor encapsulation according to claim 1, which is a copolymer comprising 0 to 45% by weight of methacrylic acid ester. The thermosetting resin composition for optical semiconductor encapsulation according to claim 1 or 2, wherein the acrylic polymer (A) has a weight average molecular weight of 5,000 to 200,000. When the total blending amount of the acrylic polymer (A) and the mixed monomer (B) is 100 parts by weight, the blending amount of the acrylic polymer (A) is 20 to 60 parts by weight of the mixed monomer (B). The blending amount is 40 to 80 parts by weight, the blending amount of the antioxidant (D) is 0.1 to 1.2 parts by weight, and the blending amount of the radical polymerization initiator (C) is based on the mixed monomer (B). 0.1 to 1% by weight, and the blending amount of acrylic acid and / or methacrylic acid (b1) is 1.0 to 1.2 moles per mole of epoxy groups contained in the acrylic polymer (A). The thermosetting resin composition for optical semiconductor sealing in any one of Claim 1 thru | or 3. The thermosetting resin composition for optical semiconductor encapsulation according to any one of claims 1 to 4, wherein the antioxidant (D) is pentaerythritol diphosphite and / or alkyldiaryl phosphite. Hardened | cured material obtained by hardening the thermosetting resin composition for optical semiconductor sealing in any one of Claim 1 thru | or 5. An optical semiconductor sealed with the cured product according to claim 6.