JP4802667B2 - Epoxy resin adhesive composition and optical semiconductor adhesive using the same - Google Patents

Description

  The present invention relates to an epoxy resin adhesive composition and an adhesive for optical semiconductors using the same, and more specifically, it can suppress short wavelength absorptivity, UV resistance, weather resistance, heat resistance, light transmission and storage stability. Epoxy resin adhesive composition having excellent coating properties and excellent transmission of wavelengths emitted from optical semiconductors, which can be used for bonding of semiconductor devices for mounting optical semiconductor chips and various parts. The present invention relates to an adhesive for optical semiconductors using the same.

  Optical semiconductors such as light-emitting diodes (LEDs) and laser diodes are composed of GaP-based, GaAlAs-based, GaInAlAs-based, GaInAlP-based compounds, etc., and it is necessary to flow electricity from the top and bottom surfaces of the semiconductor due to their structure. .

  When these LEDs are bonded to a lead frame or a substrate, an epoxy resin composition called a conductive adhesive is used as an adhesive that conducts electricity, and bonds the lower surface of the LED or the like to the lead frame or the substrate. Thus, light reflection, electrical and thermal conduction are obtained. Further, on the upper surface of the LED or the like, a thin conductive wire made of gold or the like called a fine wire is used to join the LED to the lead frame or the substrate to obtain electrical conduction.

These conventional LEDs can emit wavelengths from infrared to green, but it has been considered difficult to emit many wavelengths lower than green.
However, due to recent technological innovations, it has been found that GaN-based semiconductor compounds emit many wavelengths shorter than green. These GaN-based semiconductor compounds can emit wavelengths of about 550 nm or less, and can emit wavelengths such as green, blue, and ultraviolet rays.

  GaN-based semiconductor compounds have different structures from the above-mentioned GaP-based LEDs, etc., and there are those that obtain continuity from the lower surface and those that do not require continuity. Bonding is performed using a conductive adhesive or an epoxy resin composition having no electrical conductivity.

  However, conventional conductive adhesives and epoxy resin compositions use general-purpose epoxy resins such as bisphenol A type epoxy resins and phenol novolac type epoxy resins, so they will discolor when used for a long time. A problem has arisen. The cause of discoloration is considered to be that a general-purpose epoxy resin absorbs a wavelength of 500 to 450 nm or less, and the absorbed energy changes the structure of the epoxy resin. Further, since the wavelength energy is absorbed, the light emitted from the LED or the like is attenuated, and there is a problem that it cannot be brightened.

  Furthermore, in order to extract many wavelengths emitted by the GaN-based semiconductor compound to the outside, the conductive adhesive or epoxy resin composition reflects more wavelengths, or allows the wavelength to pass through the epoxy resin composition, It is necessary to reflect a lot on the bonded substrate portion.

  On the other hand, in order to solve these problems, alicyclic epoxy resins and hydrogenated epoxy resins may be used, but generally acid anhydrides such as methylhexahydrophthalic anhydride and nadic acid anhydride are used. A system curing agent will be used.

  In this case, a transparent cured product can be obtained, and a product with good permeability can be obtained. However, the one-component formulation has a short pot life and has a problem in terms of workability. In addition, by using dicyandiamide, a phenolic curing agent, etc., one-pack type compounding is possible, but the cured product is colored, absorbs wavelengths of 500 to 450 nm or less, and reflects the light emitted. There was a problem in that it decreased.

  In addition, LEDs that develop all colors from red to blue have been put into practical use, and it is expected that they will be actively used outdoors as traffic lights and information boards. Therefore, improvement in weather resistance is also strongly desired for the epoxy resin composition.

  For these reasons, an epoxy resin composition comprising a hydrogenated epoxy resin, a cationic polymerization initiator, an aromatic onium salt, a phenolic antioxidant, and a phosphorus compound has been proposed (see, for example, Patent Document 1). If this is used, the problem of coloring due to resin coloring and thermal history is avoided, and it is considered that a cured product having excellent weather resistance and toughness can be obtained.

  However, the cationic polymerization initiator contains an element that is not preferable as an electronic material, such as a sulfur compound, a phosphorus compound, a halide, or an ammonium ion. Aromatic onium salts can be problematic in that the solubility in the resin is not sufficiently high and the reactivity is not uniform, and metal ions remain in the cured resin. In addition, phenolic antioxidants are effective in improving the weather resistance, but have a problem that the yellow color changes with time. Furthermore, phosphorus compounds may ionize under certain conditions, forming compounds with semiconductors and causing defects.

  In order to solve such problems, an epoxy group-containing compound containing an alicyclic epoxy and a silanol group, or a compound containing a hydrolyzable group directly bonded to a silicon atom, and an organotin compound are contained. An epoxy resin composition is proposed. (See Patent Document 2.)

  The cured product of this epoxy resin composition is suitable for coating because it is excellent in transparency, but by using an alicyclic epoxy compound, it is excellent in weather resistance and also in storage stability. It is considered to be. However, a cured product of about 120 to 150 ° C. cannot obtain an adhesive force, and in order to obtain an adhesive force, it must be heated to 200 ° C. or higher, so that it cannot be used for an electronic component using an organic substrate. Was pointed out.

  In addition, the conductive paste comprising an organic binder, a solvent and / or a monomer, and a conductive powder, and including a silver-based powder as the conductive powder, includes at least one benzotriazole skeleton in the molecule, and has a functional group There has been proposed a conductive paste containing a compound having a methacryloyl group or a hydroxyl group in an amount of 0.1 to 10% based on the resin solid content (see, for example, Patent Document 3).

  Furthermore, as an insulating paste related to this, an insulating paste excellent in ultraviolet resistance and weather resistance has been proposed (see Patent Document 4), and a compound containing a benzotriazole skeleton as a component acts as an ultraviolet absorber, It is said that it contributes to the improvement of UV and weather resistance. However, in order to improve the reflectance of wavelength light of an optical semiconductor, it is necessary to further improve ultraviolet resistance and weather resistance without absorbing ultraviolet light.

Therefore, the present inventor has previously developed an epoxy resin composition containing an alicyclic epoxy resin, a hydrazide-based curing agent, and a light-reflective inorganic filler as essential components (see Patent Document 5). Thereby, the short wavelength absorptivity was suppressed compared with the conventional one, and an adhesive excellent in light reflectivity, ultraviolet resistance and weather resistance could be obtained.
On the other hand, many conventional optical functional devices have been sealed with an epoxy resin that does not contain an inorganic filler in order to ensure the transparency of the resin layer. In this case, considering the heat resistance, moisture resistance, low stress, etc. of the cured product, it cannot be said that it is sufficient, and a transparent sealing material containing an inorganic filler has been developed, and an epoxy resin, a curing accelerator, an inorganic material is developed. In an epoxy resin composition containing a filler as an essential component, it has been proposed to use an epoxy resin composition in which the refractive index of a cured product of the composition and its temperature change coefficient satisfy a specific relational expression (patent) Reference 6). Thereby, the cured product maintains high transparency under various temperature environments and is excellent in heat resistance, moisture resistance, and low stress properties.

However, in the case of epoxy resin adhesives used in optical functional devices, especially optical semiconductors, the resin component changes color when left at a high temperature exceeding 100 ° C. for a long time, and the resin component also changes color due to absorption at a short wavelength. As a result, the light transmittance may be lowered, and the appearance of an epoxy resin composition that has better heat resistance and can suppress the light transmittance decline has been eagerly desired.
JP 2001-342240 (Claims) JP-A-8-3452 (Claims) JP2001-332124 (Claims) JP-A-2001-316596 (Claims) JP-A-2004-256603 (Claims) JP 2002-88223 (Claims)

  In view of the above-mentioned problems of the prior art, the object of the present invention is to suppress short wavelength absorptivity, excellent adhesion, ultraviolet resistance, weather resistance, heat resistance and storage stability, and a semiconductor for mounting an optical semiconductor chip. An epoxy resin adhesive composition having excellent coatability and excellent wavelength transmission from an optical semiconductor, and an adhesive for an optical semiconductor using the same, which can be used for bonding an apparatus assembly and various parts. It is to provide.

  As a result of intensive research to achieve the above object, the present inventor has obtained a silane compound containing a hydrolyzable group directly bonded to a silicon atom, a divalent organotin compound, and an alicyclic epoxy compound, When a specific amount of a tetravalent organotin compound and a specific light-transmitting inorganic filler are blended as essential components, the resulting epoxy resin composition does not discolor even when left at a high temperature such as 100 to 120 ° C. In addition to finding out, if this is used as an adhesive for optical semiconductors, it can suppress short wavelength absorptivity, and is excellent in light transmission, ultraviolet resistance, weather resistance, heat resistance and storage stability, adhesiveness, The present invention has been completed by finding that it can be preferably applied to GaN-based LEDs that have made remarkable progress in technological development recently.

  That is, according to the first invention of the present invention, an alicyclic epoxy compound (A), a silane compound (B) containing a hydrolyzable group directly bonded to a silicon atom, an organotin compound (C), and light An epoxy resin adhesive composition used for an optical semiconductor containing a transparent inorganic filler (D) as an essential component, wherein the organic tin compound (C) comprises a divalent organic tin compound (c1) and a tetravalent organic compound. It is a mixture with a tin compound (c2), and the content of each component is 30 to 95% by weight of (A), 0.1 to 15% by weight of (B), based on the total amount of the composition. An epoxy resin adhesive composition is provided, wherein c1) is 0.01 to 5% by weight, (c2) is 0.01 to 5% by weight, and (D) is 0.1 to 50% by weight. The

According to a second aspect of the present invention, there is provided an epoxy resin composition according to the first aspect, wherein the silane compound (B) is a silane compound not containing a nitrogen element.
According to the third invention of the present invention, in the first or second invention, the silane compound (B) is an alkoxysilane compound containing 2 or 3 hydrolyzable groups having 1 to 3 carbon atoms. An epoxy resin adhesive composition is provided.

  According to the fourth invention of the present invention, in the first invention, the mixing amount of the divalent organic tin compound (c1) and the tetravalent organic tin compound (c2) is (c2) by weight ratio. / (C1) = 1 to 20 An epoxy resin adhesive composition is provided.

According to a fifth aspect of the present invention, in the first aspect, the inorganic filler (D) has an average primary particle size of 3.0 μm or less, and the epoxy resin adhesive composition is characterized in that Is provided.
Furthermore, according to the sixth invention of the present invention, in the first or fifth invention, the inorganic filler (D) has a band gap energy of 2.8 eV or more and a refractive index of 1.2 to 1.8. An epoxy resin adhesive composition is provided.

  On the other hand, according to 7th invention of this invention, the adhesive agent for optical semiconductors which uses the epoxy resin adhesive composition in any one of 1st-6 is provided.

  By using this, the epoxy resin adhesive composition of the present invention is excellent in adhesiveness, short wavelength absorptivity, UV resistance, weather resistance, light transmission, heat resistance, and excellent coating properties. A thing is obtained. Moreover, since the adhesive for optical semiconductors using this can greatly improve the optical characteristics and reliability of a GaN-based optical semiconductor emitting a low wavelength of 550 nm or less in particular, the industrial value of the present invention is extremely great.

  Hereinafter, the epoxy resin adhesive composition of the present invention and the optical semiconductor adhesive using the same will be described in detail.

1. Epoxy resin adhesive composition The epoxy resin adhesive composition of the present invention comprises an alicyclic epoxy compound (A), a silane compound (B) containing a hydrolyzable group directly bonded to a silicon atom, and a divalent organotin compound ( c1) An epoxy resin adhesive composition used for an optical semiconductor containing a tetravalent organotin compound (c2) and a light-transmitting inorganic filler (D) at specific ratios. In addition, if viscosity adjustment is necessary, components (E) such as epoxy compounds other than alicyclic compounds, solvents, diluents, viscosity modifiers and the like can be added.

(A) Alicyclic epoxy compound The alicyclic epoxy compound is a thermosetting resin having an alicyclic portion such as cyclohexane and an epoxy portion. Hereinafter, the alicyclic epoxy compound may be referred to as an alicyclic epoxy resin.

As the alicyclic epoxy compound, an aliphatic cyclic epoxy resin obtained by epoxidizing a double bond of a cyclohexene ring with peracetic acid can be used. For example, 3,4 epoxy cyclohexyl-3 ′, 4′-cyclohexanecarboxylate, poly (epoxidized cyclohexene oxide) and the like can be mentioned. Alicyclic epoxy resins not described here can also be used. These alicyclic epoxy compounds may be used alone or in combination.
In Patent Document 6, it is described that it is preferable to use an epoxy resin having one or more naphthalene rings in one molecule. In the case of such an epoxy compound having a naphthalene ring, if it is added excessively, the naphthalene ring absorbs a short wavelength generated by the light emission of the LED, resulting in a decrease in reflectance due to the discoloration of the resin.

  In the present invention, the content of the alicyclic epoxy compound needs to be 30 to 95% by weight. When the content of the alicyclic epoxy compound is less than 30% by weight, other components are relatively increased. When the amount of the silane compound used in combination is increased, the adhesive strength may be reduced. When the amount of the organic tin compound used is increased. In addition to causing a decrease in storage stability, if the amount of inorganic filler used in combination increases, the viscosity becomes high and the coating property deteriorates. On the other hand, if it exceeds 95% by weight, the other components are relatively reduced, and a sufficient curing reaction may not be obtained. The preferable content of the alicyclic epoxy resin is in the range of 40 to 90% by weight.

(B) Silane Compound The silane compound used in the present invention refers to a compound containing a group capable of generating a silanol group by hydrolysis. Here, the silanol group means a hydroxyl group directly bonded to a silicon atom.

Examples of such silane compounds are generally vinyltrimethoxysilane containing vinyl groups, vinyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane containing epoxy groups, and 3-glycidoxypropyl. Triethoxysilane, 3-methacryloxypropyltrimethoxysilane containing methacryloxy group, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, and alkoxysilane compounds such as tetramethoxysilane, tetraethoxysilane, Methyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, diphenyldimethoxysilane, diphenyldi Toxisilane, hexyltrimethoxysilane, hexyltriethoxysilane, decyltrimethoxysilane, decyltriethoxysilane, and chlorosilane include methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, etc. Substances not described can be used if silanol groups can be generated by hydrolysis.
Of these, alkoxysilane compounds containing 2 or 3 hydrolyzable groups having 1 to 3 carbon atoms are particularly preferred. An alkoxysilane compound containing a hydrolyzable group having 4 or more carbon atoms or a low condensate thereof is not preferable because an improvement in adhesive strength cannot be expected. Further, these silane compounds containing a hydrolyzable group directly bonded to a silicon atom may be used in combination of two or more.

  In the present invention, the silane compound contains a hydrolyzable group directly bonded to a silicon atom and acts as part of a catalyst for curing the alicyclic epoxy resin. 15% by weight. If it is the range of this composition, it functions effectively as a curing catalyst according to the quantity of an epoxy resin. When it is 0.1% by weight or less, it does not act as a catalyst and the alicyclic epoxy resin cannot be cured. On the other hand, when it is 15% by weight or more, an excessive silane compound is present in the cured product, and the adhesive force is reduced.

  Further, in the present invention, it was found that when a silane compound containing no nitrogen element is used as the silane compound, the discoloration due to ultraviolet rays and the discoloration due to heat are further suppressed. The reason is not necessarily clear, but it is considered that energy by ultraviolet rays or heat breaks molecular bonds around the nitrogen element and causes coloration.

(C) Organotin Compound In the present invention, the organotin compound is composed of a divalent organotin compound (c1) and a tetravalent organotin compound (c2), and is blended at a specific ratio.

(C1) Divalent Organotin Compound In the present invention, the divalent organotin compound is not particularly limited, and any commercially available organic compound can be used. Specific examples include tin diacetate, tin dibutyrate, tin dioctate, tin dilaurate, tin distearate, tin dinaphthenate and the like. Two or more of these may be mixed.

  Similar to the silane compound, the divalent organotin compound acts as part of a catalyst for curing the alicyclic epoxy resin. Therefore, the content of the divalent organotin compound is set to 0.01% to 5% by weight. Within this range, any divalent organotin compound can act as a catalyst. On the other hand, if it is less than 0.01% by weight, the content is too small, so that the action as a catalyst is not exhibited, and if it is 5% by weight or more, the content is too much, the reactivity is increased and the storage is performed. Will cause problems with sex.

(C2) Tetravalent organotin compound As the tetravalent organotin compound used in the present invention, any commercially available organic compound can be used. Specific examples include tin tetraacetate, tin tetraoctate, tin tetralaurate, butyltin triacetate, butyltin tributylate, butyltin trioctate, butyltin trilaurate, octyltin triacetate, octyltin tributylate, octyl Tin trioctate, octyltin trilaurate, dibutyltin diacetate, dibutyltin dibutyrate, dibutyltin dioctate, dibutyltin dilaurate, dioctyltin diacetate, dioctyltin dibutyrate, dioctyltin dioctate, dibutyltin dilaurate, dibutyltin maleate, Phenyltin tributyrate, phenyltin trilaurate, butyltin trimethoxy, butyltin tributoxy, octyltin trimethoxy , Phenyltin trimethoxy, dibutyltin dimethoxy, dioctyltin dimethoxy, dioctyltin diversate, dibutyltin bistriethoxysilicate, dibutyltin bisacetylacetonate, dibutyltin bis (o-phenylphenoxide), dibutyltin oxide, dioctyltin oxide, etc. . Two or more of these may be mixed.

  Since the tetravalent organic tin compound also acts as a part of the catalyst for curing the alicyclic epoxy resin, the content of the tetravalent organic tin compound is set to 0.01% to 5% by weight. Within this range, any tetravalent organotin compound can be used as the catalyst. On the other hand, if it is less than 0.01% by weight, the content is too small, so that the catalytic action is not exerted, and if it is 5% by weight or more, the content is too much, so that the reactivity is increased and the storability is increased. Problems arise.

In the present invention, a divalent organotin compound and a tetravalent organotin compound are used as essential components, and these are mixed and used. When a divalent organotin compound or a tetravalent organotin compound is used alone, an adhesive cured product can be obtained. However, in the case of a divalent organotin compound, the storage stability at room temperature is inferior and is being used. On the other hand, in the case of a tetravalent organic tin compound, there are some which are inferior in storage stability at room temperature as in the case of a divalent organic tin compound, or are excellent in storage stability but have sufficient adhesion However, there is a problem that a high curing temperature of 200 ° C. or higher is required to have the above, and there is a problem that it cannot be used for an electronic component composed of an organic material substrate or the like.
On the other hand, according to the present invention, the epoxy resin adhesive composition is prepared by combining a divalent organotin compound and a tetravalent organotin compound at a specific ratio. It is excellent also in the property, and the hardened | cured material which hardens | cures at the low temperature of 120-150 degreeC and has high intensity | strength adhesiveness can be obtained.

  The ratio of the divalent organotin compound (c1) to the tetravalent organotin compound (c2) is not particularly limited in the present invention, but the weight ratio of (c2) / (c1) is 1 to 20, particularly 1 to 10. A range of is desirable. This is when the divalent organotin compound (c1) is too much, and when the weight ratio of (c2) / (c1) is less than 1, the storage stability, which is a disadvantage of the divalent organotin compound, is gradually deteriorated. There is. On the other hand, if the tetravalent organotin compound (c2) is too much and the weight ratio exceeds 20, the reactivity may gradually decrease.

  These phenomena indicate that although the tetravalent organic tin compound is less reactive with the epoxy resin than the divalent organic tin compound, it is mixed with the divalent organic tin compound at a specific ratio. It is presumed that by heating at the time of bonding, it changes to a divalent organotin compound rich in reactivity. Since the tetravalent organotin compound has such a reactivity, it has adequate storage properties and therefore has sufficient storage characteristics.

(D) Inorganic filler The inorganic filler used in the present invention is a light-transmitting inorganic particle. This inorganic filler improves the strength of the cured epoxy resin, contributes to adjusting the viscosity, and further has the feature of not absorbing the light and wavelength emitted from the LED as much as possible. Function.

In the present invention, as the inorganic filler, it is more desirable to use inorganic particles having a band gap energy of 2.8 eV or more and a refractive index of 1.2 to 1.8. This is because when the band gap energy of the inorganic particles is 2.8 eV or more, the light having the emitted wavelength is not absorbed by the inorganic particles. In general, wavelength absorption in an inorganic compound is mainly caused by excitation absorption of a semiconductor compound, and the energy corresponding to this energy is the band gap energy of the inorganic compound. When the band gap energy is less than 2.8 eV, the wavelength absorption region of the particles becomes 440 nm or more, and light is absorbed by the emitted LED or the like.
In general, many epoxy resins exhibit a refractive index of around 1.5 to 1.6. Accordingly, when inorganic particles having a refractive index of 1.2 to 1.8, which is close to the refractive index, are used, light transmittance can be obtained. In particular, it is preferable to use inorganic particles having a refractive index of about 1.5 to 1.6 equivalent to the refractive index of the epoxy resin. If the refractive index is out of the range of 1.2 to 1.8, light transmittance may not be obtained.

For this reason, the inorganic particles are not particularly limited by the size of the particle size as long as the refractive index is within the above range. If the refractive index of the inorganic particles is out of this range, the average particle size of the primary particles is desirably 3.0 μm or less. When the average particle size exceeds 3.0 μm, the light transmittance may be lowered depending on the type of the inorganic filler. Therefore, the inorganic filler preferably has an average primary particle size of 3.0 μm or less, particularly 0.8 μm or less. If this condition is satisfied, light having a wavelength of 0.4 to 0.8 μm is not blocked, so that there is almost no influence on light transmittance. When the average particle size of the primary particles is 0.4 μm or less, and further 0.25 μm or less, the light transmittance is further improved.
It is desirable that the primary particles of the inorganic filler are present in a dispersed state in the composition. If they can aggregate to form secondary particles, a means such as blending a dispersing agent is used. It is preferable to take. In the present invention, the silane compound may function as a dispersant.

In addition, the color of the inorganic particles is not particularly limited, but in order to prevent light wavelength absorption, white powder or powder having the same color as the wavelength of light emitted from the LED or the like to which it adheres is desirable.
Examples of such inorganic particles include silicon fluoride, magnesium oxide, aluminum oxide, and silicon dioxide. Of these, silicon dioxide is particularly preferable. These particles (powder) can be used alone, but two or more kinds may be mixed and used.

The amount of inorganic particles added is 0.1 to 50% by weight. This is because when the added amount is less than 0.1% by weight, the function as a thixotropic agent that the inorganic filler gives to the composition cannot be obtained, while when it is more than 50% by weight, the thixotropy becomes high. This is because the viscosity is too high and the viscosity becomes too high, making it difficult to apply and lowering the workability. The preferred content is in the range of 3 to 40% by weight, more preferably 5 to 30% by weight.
In Patent Document 2, an organotin compound is blended, but it is particularly preferable to use only one tetravalent compound, and there is no specific example of an inorganic filler. Therefore, the low-temperature curing performance at 120 to 150 ° C. required by the present invention is insufficient, and the properties as an adhesive cannot be expected.

(E) Others In the present invention, if necessary, a non-alicyclic epoxy compound and other resin components, a solvent, a diluent, a viscosity modifier, a dispersant and the like do not affect the properties for viscosity adjustment. May be added.

These additives are classified into those that are incorporated into the cured product by reacting the epoxy resin with the additive or the additive itself during the curing reaction, and those that are not incorporated into the cured product. Those having no ring are desirable. In the case of a substance having a benzene ring, if it is added excessively, the benzene ring absorbs the wavelength generated by the light emission of the LED and causes a decrease in the reflectivity, etc., so the content needs attention.
Additives that can be incorporated into the cured product include phenyl glycidyl ether containing 2-epoxy glycidyl ether at one end in the structure and neopentyl glycol containing 2 or more epoxies in the structure. Diglycidyl ether, 1,6-hexanediol diglycidyl ether, bisphenol A type epoxy resin that is an epoxy resin other than alicyclic, bisphenol F type epoxy resin, phenol novolac type epoxy resin, hydrogenated bisphenol A type epoxy resin Known epoxy resins such as

On the other hand, in the case of a product that is not taken into the cured product, it may have any structure as long as it is all volatile at the time of curing.
Examples of the solvent that does not react with the epoxy resin include 2,2,4-trimethyl-3-hydroxydipentaneisobutyrate, 2,2,4-trimethylpentane-1,3-isobutyrate, isobutylbutyrate, ethylene glycol monomethyl ether, Examples thereof include ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, and ethyl 2-hydroxypropanoate.

2. Adhesive for optical semiconductor The above epoxy resin composition is suitable for bonding an assembly of a semiconductor device on which an optical semiconductor chip is mounted and various components.

  The adhesive for optical semiconductors of the present invention includes light from light receiving elements such as LEDs, phototransistors, photodiodes, photocouplers, CCDs (charge coupled devices), EPROMs (erasable programmable read only memories), photosensors, and light emitting elements. It has excellent adhesiveness, hot strength, transmittance, and discoloration that are not found in conventional epoxy resin compositions. In particular, a large effect can be expected when used when bonding GaN-based LEDs.

  The evaluation methods (conditions) of these characteristics will be described in the following examples. The adhesiveness is 60N or more, the hot strength is 5N or more, the transmittance is 80% or more, and the color change (ΔE) is less than 5. It is excellent.

The method of using this adhesive is not particularly limited and varies depending on the composition, but after dropping this epoxy resin adhesive composition on the substrate and placing the optical semiconductor chip, for example, an oven at 50 to 250 ° C. It may be left for 20 to 300 minutes in the inside or left on a hot plate at 150 to 300 ° C. for 10 to 300 seconds to be cured.
In the case of curing in an oven, if the temperature is less than 50 ° C. or less than 20 minutes, curing of the adhesive becomes insufficient, and if the temperature exceeds 250 ° C. and exceeds 300 minutes, the resin component may be decomposed. Similarly, when cured on a hot plate, the curing reaction does not proceed sufficiently at 150 ° C. or lower, resulting in insufficient curing. If the temperature exceeds 300 ° C. for 300 seconds, the resin component may be decomposed.

  EXAMPLES Hereinafter, although this invention is shown concretely using an Example and a comparative example, this invention is not limited at all by these. The raw materials used are as follows.

Epoxy compound Alicyclic epoxy resin (a): 3,4-epoxycyclohexyl-3 ′, 4′-cyclohexanecarboxylate.
Epoxy resin (b): Bisphenol A type epoxy resin.
Silane compound Silane compound (a): 3-glycidoxypropyltrimethoxysilane.
Silane compound (b): 3-methacryloxypropyltrimethoxysilane.
Silane compound (c): 3-aminopropyltrimethoxysilanesilane.
Organometallic compound Divalent organotin compound: Tin dioctate Tetravalent organotin compound: Butyltin triacetate Organoaluminum compound: Aluminum tris (ethyl acetoacetate)
Organic zirconium compound: Zirconium acetylacetonate Inorganic filler Inorganic particles (a): Commercially available silicon dioxide powder White powder having a band gap energy of 2.8 eV or more and an average particle size of 0.2 μm.
Inorganic particles (b): Commercially available copper oxide powder A reddish brown powder having a band gap energy of less than 2.8 eV and an average particle size of 0.3 μm.
Inorganic particles (c): Commercially available silicon dioxide powder White powder having a band gap energy of 2.8 eV or more and an average particle size of 3.1 μm.
Other formulations Acid anhydride curing agent: MH-700, manufactured by Shin Nippon Rika Co., Ltd.
Curing catalyst: Quaternary phosphonium bromide Additive (a): Viscosity modifier of epoxy resin composition Butyl carbitol which is not incorporated into the structure during the curing reaction and volatilizes.
Additive (b): Viscosity modifier of epoxy resin composition Bisphenol F type epoxy resin incorporated into the structure during the curing reaction.

Evaluation items and evaluation methods are as follows.
Adhesive strength:
An epoxy resin adhesive composition is dropped on a stainless steel substrate, a 1.5 mm square silicon chip is placed, left in a 120 ° C. oven for 60 minutes, and then left in a 150 ° C. oven for 60 minutes to cure. I let you. After cooling to room temperature, a force was applied to the silicon chip from the horizontal direction with respect to the stainless steel substrate, and the force when the silicon chip was peeled was measured as an adhesive strength. If the adhesive strength was 60 N or more, it was considered acceptable.
Hot strength:
An epoxy resin adhesive composition is dropped on a stainless steel substrate, a 1.5 mm square silicon chip is placed, left in an oven at 120 ° C. for 60 minutes, and then left in an oven at 150 ° C. for 60 minutes to be cured. It was. After cooling to room temperature, the stainless steel substrate is allowed to stand on a hot plate heated to 250 ° C. for 20 seconds, and then heated while applying force to the silicon chip from the horizontal direction with respect to the stainless steel substrate. The force at the time of peeling was measured as the hot strength. If the hot strength was 5N or more, it was considered acceptable.
Transmittance:
The epoxy resin adhesive composition is allowed to stand in an oven at 120 ° C. for 60 minutes, and then cured in an oven at 150 ° C. for 60 minutes, and then formed into a strip of 15 × 30 × 0.5 mm. A measurement sample was prepared. This sample was set in a spectrophotometer U-4001 manufactured by Hitachi, Ltd., and the light transmittance at 460 nm was measured. If the transmittance was 80% or more, it was considered acceptable.
Heat discoloration:
The epoxy resin adhesive composition is printed on a glass substrate so as to be 20 × 20 × 0.1 mm, left in an oven at 120 ° C. for 60 minutes, and then left in an oven at 150 ° C. for 60 minutes to cure. I let you. After cooling to room temperature, each value of L ₁ , a ₁ , b ₁ was measured with a color difference meter. Next, after leaving the sample in an oven at 120 ° C. for 500 hours, each value of L ₂ , a ₂ , and b ₂ was measured again with a color difference meter. From these values, ΔE = √ {(L ₁ −L ₂ ) ² + (a ₁ −a ₂ ) ² + (b ₁ −b ₂ ) ² } is calculated, and ΔE is less than 5 In the case of, “◯” was given because there was little discoloration, and “X” was given if there was a lot of discoloration when 5 or more. Note that L ₁ , a ₁ , b ₁ and L ₂ , a ₂ , b ₂ values are measured values of the L ^* a ^* b ^* color system before heating and after 500 hours of heating, respectively, and L is lightness , A, b mean chromaticity.
UV discoloration resistance:
The epoxy resin adhesive composition is printed on a glass substrate so as to be 20 × 20 × 0.1 mm, left in an oven at 120 ° C. for 60 minutes, and then left in an oven at 150 ° C. for 60 minutes to be cured. It was. After cooling to room temperature, each value of L ₁ , a ₁ , b ₁ was measured with a color difference meter. Next, a 365 nm center ultraviolet lamp was applied to the sample for 1 hour, and each value of L ₂ , a ₂ , and b ₂ was measured again with a color difference meter. From these values, ΔE = √ {(L ₁ −L ₂ ) ² + (a ₁ −a ₂ ) ² + (b ₁ −b ₂ ) ² } is calculated, and ΔE is less than 5 In the case of, “◯” was given because there was little discoloration, and “X” was given if there was a lot of discoloration when 5 or more.
Applicability:
The epoxy resin adhesive composition filled in the syringe was continuously discharged at 1000 points from a needle having an inner diameter of 0.2 mm attached to the discharge port of the syringe. At that time, the one that is conical or hemispherical is “○”, pulls the thread to touch the adjacent point, extends linearly to the adjacent point, and the conical corner becomes higher When there were 3 or more points that were 2 mm or more, it was determined as “x”.
Storage stability:
The epoxy resin adhesive composition was placed in an ointment bottle, sealed, and left at 30 ° C. for 5 days. The viscosity before and after being left was measured with a viscometer, and “○” was indicated when the viscosity after being left was within 1.2 times the viscosity before being left, and “X” was indicated when it was over 1.2 times.
Comprehensive evaluation:
The obtained samples were examined for adhesive strength, hot strength, reflectance, heat discoloration resistance, ultraviolet discoloration resistance, coating property, and storage stability. As a result, the adhesive strength was 60 N or more, the hot strength was 5 N or more, and the transmission. The rate is 80% or more, and heat resistance discoloration resistance, ultraviolet discoloration resistance, coating property, and storage stability are only “○”, and the overall evaluation is “○”. In this case, “x” was assigned.

(Examples 1-8)
Each raw material was blended according to the weight ratio in Table 1 and kneaded with a three-roll kneader to prepare a sample of the epoxy resin adhesive composition of the present invention.
Examples 1 to 3 are composed of an epoxy resin (a), a silane compound, a divalent organic tin compound, a tetravalent organic tin compound, silicon dioxide having an average particle size of 0.2 μm, and a solvent. Example 4 was obtained by reducing the amount of silicon dioxide of Example 2 within the scope of the present invention, and Example 5 was obtained by increasing the amount of silicon dioxide of Example 2 within the scope of the present invention. Example 6 was obtained by increasing the amount of the silane compound of Example 2 and the divalent and tetravalent organotin compounds, and Example 7 was obtained by reducing the amount of the silane compound and divalent and tetravalent organotins. The ratio of the compound was changed, the inorganic powder (particles) was brought close to the upper limit of the range of the present invention, and the additive (a) was added. Example 8 is an additive (b ) Bisphenol F type epoxy incorporated into the structure during the curing reaction It is obtained by using the fat.
The obtained results are also shown in Table 1. In addition, the composition table in Table 1 is expressed in terms of% by weight with respect to the composition containing the essential component of the present invention, whereas the additive (a) and additive (b) that are not essential components are epoxy resins. Expressed in parts by weight when the composition is 100 parts by weight.

(Comparative Examples 1-9)
Each raw material was blended in the same manner as in Examples 1 to 8 and kneaded with a three-roll kneader to prepare a comparative epoxy resin adhesive composition sample. The evaluation results obtained are also shown in Table 2 as in Table 1.
In Comparative Example 1, the organotin compound of Example 2 was changed to an organoaluminum compound, and in Comparative Example 2, the organotin compound of Example 2 was changed to an organozirconium compound.
In Comparative Example 3, a known alicyclic epoxy resin, a curing system using an acid anhydride curing agent and a curing catalyst was used, and silicon dioxide having an average particle size of 0.2 μm was mixed therewith.
In Comparative Example 4, the silicon dioxide powder of Example 2 was not used, but a light-impermeable copper oxide powder was used.
In Comparative Example 5, instead of the silicon dioxide powder of Example 2, a silicon dioxide powder having an average particle diameter of 3.1 μm having difficulty in light transmission is used.
In Comparative Example 6, the epoxy resin component of Example 2 was replaced with a non-alicyclic bisphenol A type epoxy resin.
In Comparative Example 7, a curing system containing a bisphenol A type epoxy resin, an acid anhydride curing agent, and a catalyst was used, and light transmissive silicon dioxide powder was mixed.
In Comparative Example 8, only a divalent organotin compound was used as the organometallic compound.
Comparative Example 9 is a case where only a tetravalent organotin compound is used as the organometallic compound.

"Evaluation and Discussion"
As is apparent from Table 1, the epoxy resin adhesive compositions of Examples 1 to 9 are excellent in adhesive strength as an adhesive, have low wavelength transmittance, deterioration against heat and ultraviolet rays, discoloration, and applicability. In addition, a cured product having excellent storage stability is obtained.
On the other hand, Comparative Example 1 is a case where an organoaluminum compound is used, but the adhesive strength, hot strength, transmittance, heat discoloration resistance and ultraviolet discoloration resistance, and applicability are excellent, but the storage stability is inferior. The overall evaluation was “x”.
Comparative Example 2 is a case where an organic zirconium compound was used, but, as in Comparative Example 1, the adhesive strength, hot strength, permeability, heat discoloration resistance and ultraviolet discoloration resistance, and coating properties were excellent, but storage stability The overall evaluation was “x”.
In Comparative Example 3, an acid anhydride and a curing catalyst are used as a known curing agent component, but there is no problem in adhesive strength, hot strength, transmittance, heat discoloration resistance and ultraviolet discoloration resistance, and coatability. However, it was inferior in storage stability and was "x" as comprehensive evaluation.
Comparative Example 4 uses light-impermeable copper oxide as the inorganic filler. In this example, the color of the cured product is also black and the transmittance is low. Moreover, although the heat discoloration resistance and the ultraviolet discoloration resistance are “◯”, this is considered to be because the resin component was discolored because it was originally black so that it was not so noticeable.
Comparative Example 5 uses silicon dioxide having an average particle size of 3.1 μm as the inorganic filler. The transmittance was lowered due to the large average particle size.
Comparative Example 6 was obtained by replacing the epoxy resin component with a non-alicyclic bisphenol A type epoxy resin which is not preferred as the present invention, but the adhesive strength is low, the ultraviolet discoloration resistance is inferior, and the overall evaluation is “x”. there were. The reason why the adhesive strength is weak seems to be that although the cured product is obtained as compared with the case of using the alicyclic epoxy resin, the curing reaction does not proceed sufficiently.
In Comparative Example 7, as in Comparative Example 6, a bisphenol A type epoxy resin was used and an acid anhydride curing agent and a curing catalyst were used. The curing reaction has progressed sufficiently, and adhesive strength and hot strength have been sufficiently obtained, but since it contains a bisphenol-A epoxy resin having a benzene ring, it is inferior in ultraviolet discoloration resistance, Since an acid anhydride curing agent and a curing catalyst were used, the storage stability was inferior, and the overall evaluation was “x”.
In Comparative Example 8, only a divalent compound was used as the organic tin compound, and although the adhesive strength, transmittance, discoloration and the like were sufficient, the viscosity was 1.5 times the initial value and storage stability was achieved. Since it was inferior in property, comprehensive evaluation was "x".
In Comparative Example 9, only a tetravalent compound was used as the organotin compound, and the curing temperature was not sufficient under the test conditions. Therefore, it was estimated that the curing was insufficient. Therefore, adhesive strength and hot strength were desired. The overall evaluation was “x”.

Claims (7)

Contains alicyclic epoxy compound (A), silane compound (B) containing a hydrolyzable group directly bonded to a silicon atom, organotin compound (C), and light-transmitting inorganic filler (D) as essential components An epoxy resin adhesive composition used for optical semiconductors,
The organotin compound (C) is a mixture of a divalent organotin compound (c1) and a tetravalent organotin compound (c2), and the content of each component is based on the total amount of the composition, A) is 30 to 95% by weight, (B) is 0.1 to 15% by weight, (c1) is 0.01 to 5% by weight, (c2) is 0.01 to 5% by weight, and (D) is An epoxy resin adhesive composition characterized by being 0.1 to 50% by weight.   The epoxy resin composition according to claim 1, wherein the silane compound (B) is a silane compound containing no nitrogen element.   The epoxy resin adhesive composition according to claim 1 or 2, wherein the silane compound (B) is an alkoxysilane compound containing 2 or 3 hydrolyzable groups having 1 to 3 carbon atoms.   The mixed amount of the divalent organotin compound (c1) and the tetravalent organotin compound (c2) is (c2) / (c1) = 1 to 20 in weight ratio. The epoxy resin adhesive composition as described.   The epoxy resin adhesive composition according to claim 1, wherein the inorganic filler (D) has an average primary particle diameter of 3.0 µm or less.   6. The epoxy resin adhesive composition according to claim 1, wherein the inorganic filler (D) has a band gap energy of 2.8 eV or more and a refractive index of 1.2 to 1.8.   The adhesive for optical semiconductors which uses the epoxy resin adhesive composition in any one of Claims 1-6.