Epoxy resin composition for semiconductor sealing

Abstract: An epoxy resin composition for semiconductor sealing which comprises, as essential components, (A) an epoxy resin comprising 50-100% by weight, based on total epoxy resin amount, of a polyfunctional epoxy resin represented by the formula (I) wherein n and m are each an integer of 0 or more, n + m = 1-10, and R₁, R₂ and R₃ which may be the same or different, are each selected from hydrogen atom, an alkyl group and a halogen atom, with the proviso that all of R₁, R₂ and R₃ must not be hydrogen atom simultaneously, (B) a phenolic resin curing agent, (C) a silica filler, and (D) a curing accelerator.

Description: The present invention relates to an epoxy resin composition for semiconductor sealing which has excellent resistance to soldering stress. In recent years, development in semiconductor-related technologies has been directed from lightness, thinness and smallness to higher component mounting density. Accordingly, memory integration is becoming larger and mounting method is shifting from through-hole mounting to surface mounting. In this connection, packages are changing from conventional DIP (Dual Inline Package) type packages to small and thin packages enabling surface mounting, i.e., flat package, SOP (Small Outline Package), SOJ (Small Outline with J-leads) and PLCC (Plastic Leaded Chip Carrier). However, the latter packages, being small and thin, have problems such as occurrence of cracks due to stress and reduction in moisture resistance due to the cracks. In the packages for surface mounting, attention is paid particularly to a problem that the packages undergo a quick temperature change at the time of soldering of leads thereto for surface mounting and resultantly generate cracks. In order to solve the problem, there were made various attempts to reduce the thermal shock imparted at the time of soldering, for example, an attempt of adding a thermoplastic oligomer to the epoxy resin composition used for semiconductor sealing (Japanese Patent Application Kokai (Laid-Open) No. 115849/1987), an attempt of adding various silicone compounds to said epoxy resin composition (Japanese Patent Application Kokai (Laid-Open) No. 115850/1987, Japanese Patent Kokoku (Post-Exam. Publication) Nos. 116654/1987 and 128162/1987), and an attempt of using a silicone-modified epoxy resin composition (Japanese Patent Application Kokai (Laid-Open) No. 136860/1987). In each of these attempts, however, the composition generated cracks in the package at the time of soldering, and hence it was impossible to obtain a highly reliable epoxy resin composition for semiconductor sealing. Meanwhile, in order to obtain a heat-resistant epoxy resin composition having excellent resistance to soldering stress, there was investigated, for example, the use of a polyfunctional epoxy resin as the resin component for said composition [Japanese Patent Application Kokai (Laid-Open) No. 168620/1986]. The use of such a polyfunction epoxy resin gave a higher crosslinking density and higher heat resistance, but the resulting epoxy resin composition had no sufficient resistance to soldering stress particularly when exposed to high temperatures of 200-300°C. The object of the present invention is to overcome the above problems and to provide an epoxy resin composition for semiconductor sealing which has very high resistance to soldering stress. The present invention provides an epoxy resin composition for semiconductor sealing which comprises, as essential components, (A) an epoxy resin comprising 50-100% by weight, based on total epoxy resin amount, of a polyfunctional epoxy resin represented by the formula (I) wherein each of m and n is an integer of 0 or more, n + m = 1-10, R 1 is a methyl group, R 2 is a tert.-butyl group and R 3 is a hydrogen atom, (B) a phenolic resin curing agent comprising 30-100% by weight, based on the total phenolic resin curing agent amount, of a paraxylene-modified phenolic resin curing agent represented by the formula (II): wherein n is an integer of 0-5; a phenolic resin curing agent comprising 50-100% by weight, based on the total phenolic resin curing agent amount, of a tri(hydroxyphenyl)-methane type phenolic resin curing agent represented by the formula (III): wherein each of n and m is an integer of 0-10, n + m = 1-10 and each R is independently selected from a hydrogen atom, a methyl group, an ethyl group, a propyl group, a butyl group and a tert-butyl group; or a phenolic resin curing agent comprising 50-100% by weight, based on the total phenolic resin curing agent amount, of a dicyclopentadiene-modified phenolic resin curing agent represented by the formula (IV): wherein n is an integer of 0-5 and each R is independently an atom or group selected from a hydrogen atom, a halogen atom and an alkyl group of 1-4 carbon atoms, and where the phenolic resin curing agent comprises 30-100% by weight of the paraxylene-modified phenolic resin curing agent represented by the formula (II) or 50-100% by weight of the tri(hydroxyphenyl)-methane phenolic resin curing agent represented by the formula (III), in formula I (n+1):m = 3:1; and where the phenolic resin curing agent comprises 50-100% by weight of the dicyclopentadiene-modified phenolic resin curing agent represented by the formula (IV), in formula I (n+1):m = 3:1-0, (C) a silica filler, and (D) a curing accelerator. Thus, there can be obtained an epoxy resin composition having very high resistance to soldering stress which has been unattainable with the use of a conventional epoxy resin alone. The epoxy resin composition of the present invention can exhibit an utmost resistance to soldering stress by controlling the amount of the epoxy resin used therein. In order for the epoxy resin composition to show sufficient resistance to soldering stress, it is desirable that the composition contain preferably at least 50% by weight, more preferably at least 70% by weight, based on total epoxy resin amount, of a polyfunctional epoxy resin represented by the formula (I). When the amount of the polyfunctional epoxy resin is less than 50% by weight based on total epoxy resin amount, the resulting epoxy resin composition has a lowercrosslinking density and accordingly reduced resistance to soldering stress. In the formula (I), R 1 is a methyl group, R 2 is a tert-butyl group, and R 3 is a hydrogen atom. In the formula (I), the ratio of n : m is preferably 1 : 0.1-0.6, more preferably 1 : 0.2-0.4. When the ratio of n : m is such that n is 1 and m is smaller than 0.1, the resulting epoxy resin composition tends to have reduced curability during molding, reducing the moldability, although it poses no practical problem. When m is larger than 0.6, the resulting epoxy resin composition may have a tendency to show increased water absorbability, higher higher thermal shock when immersed in solder, and poorer resistance to soldering stress. When n + m = 0, or when the polyfunctional epoxy resin is replaced by a mono- or bi-functional epoxy resin, the resulting epoxy resin composition shows reduced curability, poor moldability, insufficient crosslinking density, inferior heat resistance and substantially no resistance to soldering stress. When n + m > 10, the epoxy resin composition shows reduced fluidity and poor moldability. The epoxy resin referred to herein includes all epoxy resins having epoxy group(s), for example, bisphenol type epoxy resins, novolac type epoxy resins and triazine nucleus-containing epoxy resins. The silica filler used in the present invention includes porous silica powder, secondary agglomerated silica powder, silica powder obtained by grinding porous silica powder and/or secondary agglomerated silica powder, fused silica powder, crystalline silica powder, etc. If necessary, other fillers such as alumina and the like may be added to the epoxy resin composition of the present invention. The phenolic resin curing agent used in the present invention includes phenolic novolac resin, cresol novolac resin, paraxylene-modified phenolic resin, tris(hydroxyphenyl)methane type phenolic resin, dicyclopentadiene-modified phenolic resin, etc. If necessary, other curing agents such as acid anhydride and the like may be added to the epoxy resin composition of the present invention. When the silica filler (C) contains 5-80% by weight, based on total filler amount, of a porous silica powder having an average particle diameter of 5-40 µm, an apparent density of 0.1-0.6 g/cc and a specific surface area of 5-20 m 2 /g, there is provided a preferable embodiment of the present invention. When the porous silica powder has an average particle diameter of less than 5 µm or more than 40 µm, the resulting epoxy resin composition shows reduced fluidity, which is less preferable. When the porous silica powder has an apparent density of more than 0.6 g/cc, the resulting composition may have some tendency easily to generate cracks owing to thermal stress by soldering and accordingly to show reduced moisture resistance, which is less preferable. When the porous silica powder has a specific surface area of less than 5 m 2 /g, the resulting composition may have some tendency easily to generate cracks at soldering step and accordingly to show reduced moisture resistance. When the porous silica powder has a specific surface area of more than 20 m 2 /g, the composition shows significantly reduced fluidity, which is less preferable. When the porous silica powder is used in an amount of less than 5% by weight based on total filler amount, the resulting composition may have some tendency easily to generate cracks at soldering step and accordingly to show reduced moisture resistance, which may make it difficult to obtain a composition having preferred properties. When the porous silica powder is used in an amount of more than 80% by weight based on total filler amount, the resulting composition shows reduced fluidity and poorermoldability, which is not as suitable for practical application. When the silica filler (C) contains 5-80% by weight, based on total filler amount, of a secondary agglomerated silica powder having an average particle diameter of 20-60 µm, an apparent density of 0.1-0.6 g/cc and a specific surface area of 5 m 2 /g or less, there is also provided a preferable embodiment of the present invention. When the secondary agglomerated silica powder has an average particle diameter of less than 20 µm, the resulting epoxy resin composition may have some tendency easily to generate cracks owing to thermal stress by soldering and, when the silica powder has an average particle diameter of more than 60 µm, the composition shows reduced moldability, both of which are less preferable. The average particle diameter of the secondary agglomerated silica powder is preferably 20-40 µm. When the secondary agglomerated silica powder has an apparent density of more than 0.6 g/cc, the resulting composition may have some tendency easily to generate cracks owing to thermal stress by soldering and accordingly to show reduced moisture resistance, which is less preferable. When the second agglomerated silica powder has a specific surface area of more than 5 m 2 /g, the resulting composition may have some tendency easily to generate cracks at soldering step and accordingly to show reduced moisture resistance and significantly reduced fluidity, which is less preferable. When the second agglomerated silica powder is contained in an amount of less than 5% by weight based on total filler amount, the resulting composition may have some tendency easily to generate cracks at soldering step and accordingly to show reduced moisture resistance, which makes it difficult to obtain a composition having preferred properties. When the second agglomerated silica powder is contained in an amount of more than 80% by weight based on total filler amount, the resulting composition may have some tendency to show reduced fluidity and poorer moldability, which is not as suitable for practical application. As mentioned above, when the second agglomerated silica powder or the porous silica powder is contained in an amount of more than 80% by weight based on total filler amount, the resulting composition tends to show reduced fluidity and poorer moldability. This has been counteracted by using, as the polyfunctional epoxy resin, a polyfunctional epoxy resin of the formula (I) wherein m = 0 and, as the silica filler (C), 5-100% by weight, based on total filler amount, of a silica powder having an average particle diameter of 3-20 µm, an apparent density of 0.1-0.8 g/cc, a specific surface area of 1-20 m 2 /g and a boiled linseed oil absorbability of 0.2-1.2 ml/g, obtained by grinding a secondary agglomerated silica powder and/or a porous silica powder. That is, as a result, there has been obtained an epoxy resin composition for semiconductor sealing, which has very high resistance to soldering stress without reducing its moldability, as compared with the conventional resin compositions for semiconductor sealing. As the polyfunctional epoxy resin of the formula (I) wherein m = 0, there are preferred those of the formula (I) wherein n = 1-3. When the amount of the ground silica powder used is less than 5% by weight based on total filler amount, the resulting epoxy resin composition is less able to relax the stress generated at the time of immersion in solder and has reduced soldering stress. As mentioned before, when the secondary agglomerated silica powder and/or the porous silica powder is used as a filler, the resulting epoxy resin composition tends to show reduced fluidity and poorer moldability. However, by grinding a secondary agglomerated silica powder and/or a porous silica powder to reduce its boiled linseed oil absorbability, there can be obtained improved fluidity. When the silica powder obtained by grinding a secondary agglomerated silica powder and/or a porous silica powder has an average particle diameter of less than 3 pm, the resulting composition may have some tendency to generate cracks owing to soldering heat stress. When the ground silica powder has an average particle diameter of more than 20 pm, the composition shows reduced fluidity. Therefore, the average particle diameter of the ground silica powder is preferably 3-20 µm, more especially 3-10 µm. When the apparent density of the ground silica powder is less than 0.1 g/cc, the resulting composition shows reduced fluidity. When the apparent density is more than 0.8 g/cc, the composition may have some tendency to generate cracks owing to thermal stress by soldering and accordingly to show reduced moisture resistance. When the specific surface area of the ground silica powder is less than 1 m 2 /g, the resulting composition shows reduced strength when molded and may have some tendency to generate cracks at soldering step. When the specific surface area is more than 20 m 2 /g, the composition shows reduced fluidity. When the boiled linseed oil absorbability of the ground silica powder is more than 1.2 ml/g, the resulting composition shows reduced fluidity and poorer moldability. When the boiled linseed oil absorbability is less than 0.2 ml/g, the composition may have some tendency to generate cracks owing to thermal stress by soldering. In order to obtain improved resistance to soldering stress, it is desirable to use the ground silica powder in an amount of at least 5% by weight, preferably at least 20% by weight based on total filler amount. When there is used a polyfunctional epoxy resin of the formula (I) wherein m = 0, the resulting epoxy resin composition tends to show reduced curability and accordingly poorer moldability. This has been counteracted by using a polyfunctional epoxy resin of the formula (I) wherein n = 1-9, m = 1-9 and n + m = 2-10 and, as the silica filler (C), 5-100% by weight, based on total filler amount, of a silica powder having an average particle diameter of 3-20 µm, an apparent density of 0.1-0.8 g/cc, a specific surface area of 1-20 m 2 /g and a boiled linseed oil absorbability of 0.2-1.2 ml/g, obtained by grinding a secondary agglomerated silica powder and/or a porous silica powder. That is, as a result, there has been obtained an epoxy resin composition for semiconductor sealing, which has very high resistance to soldering stress without reducing its moldability, as compared with the conventional resin compositions for semiconductor sealing. As the polyfunctional epoxy resin of the formula (I) wherein n = 1-9, m = 1-9 and n + m = 2-10, there are preferred those of the formula (I) wherein (n + 1) : m = 3 : 1. The property ranges and use conditions of the ground silica powder, as well as the reasons therefor are the same as described previously. When there is used a polyfunctional epoxy resin of the formula (I) wherein (n + 1) : m = 3 : 1, there is provided a preferable embodiment of the present invention. In this case, as the silica filler (C) there can be used any of silica fillers in order to achieve the intended object of the present invention. In the above case, when the ratio of (n + 1) : m is such that (n + 1) is 3 and m is smaller than 1, the resulting composition tends to have reduced curability during molding and accordingly poorer moldability. When m is larger than 1, the composition tends to show increased water absorbability, higher thermal shock when immersed in solder, and poorer resistance to soldering stress. When there is used a polyfunctional epoxy resin of the formula (I) wherein m = 0, there is also provided a preferable embodiment of the present invention. In this case also, as the silica filler (C) there can be used any of silica fillers in order to achieve the intended object of the present invention. The case of n = 1 - 3 is particularly preferable. By using, as an epoxy resin, a polyfunctional epoxy resin of the formula (I) wherein (n + 1) : m = 3 : 1 and, as a phenolic resin curing agent, 30-100% by weight, based on total phenolic resin curing agent, of a paraxylene-modified phenolic resin curing agent represented by the formula (II) (n is an integer of 0-5), there can be obtained an epoxy resin composition for semiconductor sealing which has very high resistance to soldering stress. The phenolic resin curing agent represented by the formula (II) is obtained by condensing phenol and an aralkyl ether (α,α'-dimethoxyparaxylene) according to Friedel-Craft reaction. By using this paraxylene-modified phenolic resin, there can be obtained an epoxy resin composition having very high resistance to soldering stress which has been unobtainable according to the prior art. By controlling the amount of the paraxylene-modified phenolic resin used, the epoxy resin composition of the present invention can exhibit an utmost resistance to soldering stress. In order for the epoxy resin composition to show high resistance to soldering stress, it is desirable to use the paraxylene-modified phenolic resin in an amount of at least 30% by weight, preferably at least 50% by weight based on total phenolic resin curing agent amount. When the amount of the paraxylene-modified phenolic resin is less than 50% by weight, the resulting epoxy resin composition haslowerwater resistance, lower flexibility, lower adhesion to lead frame and reduced resistance to soldering stress. In the formula (II), n is 0-5. When n is larger than 5, the resulting composition tends to show reduced fluidity and poorer moldability. When there is used, for example, a phenolic novolac resin curing agent containing no paraxylene in the main chain, the resulting epoxy resin composition has lower water resistance, lower adhesion to lead frame, increased shock due to vaporization of steam and reduced resistance to soldering stress. By using, as an epoxy resin, a polyfunctional epoxy resin of the formula (I) wherein (n + 1) : m = 3 : 1 and, as a phenolic resin curing agent, 50-100% by weight, based on total phenolic resin curing agent amount, of a tris(hydroxyphenyl)methane type phenolic resin curing agent represented by the formula (III) (n and m are each an integer of 0-10, n + m = 1-10, and R is selected from hydrogen atom, methyl group, ethyl group, propyl group, butyl group, tert-butyl group or the combination thereof), there can also be obtained an epoxy resin composition for semiconductor sealing which has very high resistance to soldering stress. The phenolic resin curing agent represented by the formula (III) is a polyfunctional phenolic resin curing agent having at least three hydroxyl groups in the molecule. By using this polyfunctional phenolic resin curing agent, there can be obtained an epoxy resin composition having very high resistance to soldering stress which has been unobtainable according to the prior art. By controlling the amount of the above phenolic resin curing agent used, the epoxy resin composition of the present invention can exhibit an utmost resistance to soldering stress. In order for the epoxy resin composition to show high resistance to soldering stress, it is desirable to use at least 50% by weight, preferably at least 70% by weight, based on total phenolic resin curing agent amount, of a tris(hydroxyphenyl)methane type phenolic resin curing agent represented by the formula (III). When the amount of the curing agent used is less than 50% by weight, the resulting epoxy resin composition has lower crosslinking density and reduced resistance to soldering stress. In the formula (III), each R is preferably hydrogen atom or an alkyl group of 1-4 carbon atoms. When each R is an alkyl group of 5 or more carbon atoms, the phenolic resin curing agent shows reducing reactivity with the epoxy resin and the resulting epoxy resin composition has poorer curability. When there is used a phenolic resin curing agent of mono- or bi-functionally, the resulting composition has lower crosslinking density, poorer heat resistance and reduced resistance to soldering stress. In the formula (III), (n + m) is 1-10. When (n + m) is larger than 10, the resulting composition tends to show reduced fluidity and poorer moldability. By using, as an epoxy resin, a polyfunctional epoxy resin of the formula (I) wherein (n + 1) : m = 3 : 1-0 and, as a phenolic resin curing agent, 50-100% by weight, based on total phenolic resin curing agent amount, of a dicyclopentadiene-modified phenolic resin curing agent represented by the following formula (IV) the bonding of the phenolic rings to the carbocyclic moieties being in each case to the particular ring indicated (n is an integer of 0-5 and each R is an atom or group selected from hydrogen atom, a halogen atom and an alkyl group of 1-4 carbon atoms), there can also be obtained an epoxy resin composition which has very high resistance to soldering stress as compared with the conventional epoxy resin compositions. The dicyclopentadiene-modified phenolic resin curing agent having a structure represented by the formula (IV) is characterized by having in the molecule a dicyclopentadiene structure having flexibility. By using this phenolic resin curing agent, there can be obtained an epoxy resin composition having high flexibility and good resistance to soldering stress. By controlling the amount of the dicyclopentadiene-modified phenolic resin curing agent used, the epoxy resin composition of the present invention can exhibit an utmost resistance to soldering stress. In order for the epoxy resin composition to show high resistance to soldering stress, it is desirable to use the dicyclopentadiene-modified phenolic resin curing agent in an amount of at least 50% by weight, preferably at least 70% by weight based on total curing agent amount. When the amount of said curing agent is less than 50% by weight, the resulting epoxy resin composition has lower flexibility and reduced resistance to soldering stress. In preparing the epoxy resin composition of the present invention, it is preferred that the epoxy resin and the phenolic resin curing agent be used so that the number of the epoxy groups of the epoxy resin is in a range of 0.5-2 per hydroxyl group of the curing agent. When the number of said epoxy groups is less than 0.5 or more than 2, the resulting epoxy resin composition has poorer moisture resistance and poorer moldability and the cured product of said composition has poorer electrical properties. The number of the epoxy groups of the epoxy resin is preferably 1.1-1.3 per hydroxyl group of the curing agent. When the number of said epoxy groups is less than 1.1 or more than 1.3, the resulting composition tends to show increased water absorbability, increased thermal shock when immersed in solder, and poorer resistance to soldering stress. The curing accelerator (D) used in the present invention can be any curing accelerator as long as it can accelerate the reaction between the epoxy groups of the epoxy resin and the phenolic hydroxyl groups. As the curing accelerator (D), there can be used various curing accelerators conventionally used in sealing materials. There can be used, for example, diazabicycloundecane (DBU), triphenylphosphine (TPP), dimethylbenzylamine (BDMA) and 2-methylimidazole (2MZ). These compounds can be used alone or in combination of two or more. The sealing epoxy resin composition according to the present invention comprises, as essential components a polyfunctional epoxy resin, a phenolic resin curing agent, a silica filler and a curing accelerator. The composition may further comprise, if necessary, various additives such as flame retardant (e.g., silane coupling agent, brominated epoxy resin, antimony trioxide, hexabromobenzene), coloring agent (e.g., carbon black, red oxide), releasing agent (e.g., natural wax, synthetic wax), low stress additive (e.g., silicone oil, rubber) and the like. When the sealing epoxy resin composition according to the present invention is produced as a molding material, there are uniformly mixed an epoxy resin, a phenolic resin curing agent, a curing accelerator, a silica filler and other additives by means of a mixer or the like; the resulting mixture is melt-kneaded by means of a hot roll, a kneader or the like; and after cooling, the mixture is ground to obtain a molding material. This molding material can be used for sealing, coating, insulating, etc. of electronic parts and electric parts. As described above, according to the present invention, by appropriately selecting the types and amounts of a polyfunctional epoxy resin, a phenolic resin curing agent, a silica filler and a curing accelerator and compounding these components, there can be obtained an epoxy resin composition having heat resistance, flexibility and low water absorbability which has been unobtainable according to the prior art. Accordingly, by the present invention there can be obtained epoxy resin compositions having very high crack resistance when subjected to thermal stress by rapid temperature change at soldering step, and further having good moisture resistance. Therefore, the present epoxy resin composition can be suitably used for sealing, coating, insulation, etc. of electronic and electric parts, particularly high integration large chip ICs mounted on surface mounting packages and requiring high degree of reliability. Next, the present invention is described by way of Examples. Example I-1 The above materials were mixed at normal temperature by means of a mixer. The mixture was kneaded at 70-100°C by means of twin rolls. After cooling, the mixture was ground to obtain a molding material. The molding material was shaped into tablets. From the tablets was prepared a 6 x 6 mm chip for soldering crack test using a low pressure transfer molding machine under conditions of 175°C, 70 kg/cm 2 and 120 seconds. The chip was used for sealing of a 52p package. Also, a 3 x 6 mm chip for soldering-moisture resistance test was prepared in the same manner and used for sealing of a 16p SOP package. The resulting sealed test devices were subjected to the following soldering crack test and soldering moisture resistance test. Soldering crack test The sealed test device (sealed 52p package) was placed under conditions of 85°C and 85% R.H. for 48 hours and 72 hours and then immersed in a solder bath of 260°C for 10 seconds. Thereafter, the cracks formed on the surface of the sealed test device were observed using a microscope. Soldering-moisture resistance test The sealed test device (sealed 16p SOP package) was placed under conditions of 85°C and 85% R.H. for 72 hours, then immersed in a solder bath of 260°C for 10 seconds, and subjected to a pressure cooker test (125°C x 100% R.H.) to measure a time to 50% poor opening of the circuit. The results are shown in Table I. Examples I-2 to I-5 Compounding was effected according to the recipes of Table I and the subsequent kneading and grinding were effected in the same manner as in Example I-1 to obtain molding materials. From the molding materials were prepared sealed moldings for test purpose in the same manner as in Example I-1. The moldings were subjected to the same soldering crack test and soldering-moisture resistance test as in Example I-1. The test results are shown in Table I. Comparative Examples I-1 to I-6 Compounding was effected according to the recipes of Table I and the subsequent kneading and grinding were effected in the same manner as in Example I-1 to obtain molding materials. From the molding materials were prepared sealed moldings for test purpose in the same manner as in Example I-1. The moldings were subjected to the same soldering crack test and soldering-moisture resistance test as in Example I-1. The test results are shown in Table I. Example II-1 The above materials were mixed at normal temperature by means of a mixer. The mixture was kneaded at 70-100°C by means of twin rolls. After cooling, the mixture was ground to obtain a molding material. From the molding material were prepared sealed moldings for test purpose in the same manner as in Example I-1. The moldings were subjected to the same soldering crack test and soldering-moisture resistance test as in Example I-1. In these tests, the solder bath temperature was 250°C. The results are shown in Table II. Examples II-2 to II-5 Compounding was effected according to the recipes of Table II and the subsequent kneading and grinding were effected in the same manner as in Example II-1 to obtain molding materials. From the molding materials were prepared sealed moldings for test purpose in the same manner as in Example I-1. The moldings were subjected to the same soldering crack test and solderingmoisture resistance test as in Example I-1. In these tests the solder bath temperature was 250°C. The test results are shown in Table II. Comparative Examples II-1 to II-6 Compounding was effected according to the recipes of Table II and the subsequent kneading and grinding were effected in the same manner as in Example II-1 to obtain molding materials. From the molding materials were prepared sealed moldings for test purpose in the same manner as in Example I-1. The moldings were subjected to the same soldering crack test and solderingmoisture resistance test as in Example I-1. In these tests the solder bath temperature was 250°C. The test results are shown in Table II. Example III-1 The above materials were mixed at normal temperature by means of a mixer. The mixture was kneaded at 70-100°C by means of twin rolls. After cooling, the mixture was ground to obtain a molding material. From the molding material were prepared sealed moldings for test purpose in the same manner as in Example I-1. The moldings were subjected to the same soldering crack test and soldering-moisture resistance test as in Example I-1. In these tests, the solder bath temperature was 250°C. The test results are shown in Table III. Examples III-2 to III-5 Compounding was effected according to the recipes of Table III and the subsequent kneading and grinding were effected in the same manner as in Example I-1 to obtain molding materials. From these molding materials were prepared sealed moldings for test purpose in the same manner as in Example I-1. The moldings were subjected to the same soldering crack test and soldering-moisture resistance test as in Example I-1. In these tests, the solder bath temperature was 250°C. The results are shown in Table III. Comparative Examples III-1 to III-5 Compounding was effected according to the recipes of Table III and the subsequent kneading and grinding were effected in the same manner as in Example III-1 to obtain molding materials. From the molding materials were prepared sealed moldings for test purpose in the same manner as in Example I-1. The moldings were subjected to the same soldering crack test and soldering-moisture resistance test as in Example I-1. The results are shown in Table III.

Claims: An epoxy resin composition for semiconductor sealing which comprises, as essential components, (A) an epoxy resin comprising 50-100% by weight, based on total epoxy resin amount, of a polyfunctional epoxy resin represented by the formula (I) wherein each of m and n is an integer of 0 or more, n + m = 1-10, R 1 , is a methyl group, R 2 is a tert.-butyl group and R 3 is a hydrogen atom, (B) a phenolic resin curing agent comprising 30-100% by weight, based on the total phenolic resin curing agent amount, of a paraxylene-modified phenolic resin curing agent represented by the formula (II): wherein n is an integer of 0-5; a phenolic resin curing agent comprising 50-100% by weight, based on the total phenolic resin curing agent amount, of a tri(hydroxyphenyl)-methane type phenolic resin curing agent represented by the formula (III): wherein each of n and m is an integer of 0-10, n + m = 1-10 and each R is independently selected from a hydrogen atom, a methyl group, an ethyl group, a propyl group, a butyl group and a tert-butyl group; or a phenolic resin curing agent comprising 50-100% by weight, based on the total phenolic resin curing agent amount, of a dicyclopentadiene-modified phenolic resin curing agent represented by the formula (IV): wherein n is an integer of 0-5 and each R is independently an atom or group selected from a hydrogen atom, a halogen atom and an alkyl group of 1-4 carbon atoms, and where the phenolic resin curing agent comprises 30-100% by weight of the paraxylene-modified phenolic resin curing agent represented by the formula (II) or 50-100% by weight of the tri(hydroxyphenyl)-methane phenolic resin curing agent represented by the formula (III), in formula I (n+1):m = 3:1; and where the phenolic resin curing agent comprises 50-100% by weight of the dicyclopentadiene-modified phenolic resin curing agent represented by the formula (IV), in formula I (n+1):m = 3:1-0, (C) a silica filler, and (D) a curing accelerator. An epoxy resin composition according to Claim 1, which comprises 5-80% by weight, based on total filler amount, of a porous silica powder having an average particle diameter of 5-40 µm, an apparent density of 0.1-0.6 g/cc and a specific surface area of 5-20 m 2 /g. An epoxy resin composition according to Claim 1, which comprises 5-80% by weight, based on total filler amount, of a secondary agglomerated silica powder having an average particle diameter of 20-60 µm, an apparent density of 0.1-0.6 g/cc and a specific surface area of 5 m 2 /g or less. An epoxy resin composition according to Claim 1, which comprises, as the polyfunctional epoxy resin, a polyfunctional epoxy resin of the formula (I) wherein m = 0 and, as the silica filler, 5-100% by weight, based on total filler amount, of a silica powder having an average particle diameter of 3-20 µm, an apparent density of 0.1-0.8 g/cc, a specific surface area of 1-20 m 2 /g and a boiled linseed oil absorbability of 0.2-1.2 ml/g, obtained by grinding a secondary agglomerated silica powder and/or a porous silica powder. An epoxy resin composition according to Claim 4, wherein in the formula (I) n = 1-3. An epoxy resin composition according to Claim 1, which comprises, as the polyfunctional epoxy resin, a polyfunctional epoxy resin of the formula (I) wherein n = 1-9, m = 1-9 and n + m = 2-10 and, as the silica filler, 5-100% by weight, based on total filler amount, of a silica powder having an average particle diameter of 3-20 µm, an apparent density of 0.1-0.8 g/cc, a specific surface area of 1-20 m 2 /g and a boiled linseed oil absorbability of 0.2-1.2 ml/g, obtained by grinding a secondary agglomerated silica powder and/or a porous silica powder. An epoxy resin composition according to Claim 1 or 6, wherein in the formula (I) (n + 1) : m = 3 : 1. An epoxy resin composition according to Claim 1, wherein in the formula (I) m = 0. An epoxy resin composition according to Claim 8, wherein n = 1-3 in the formula (I). An epoxy resin composition according to Claim 1, wherein n = 0-2 in the formula (II). An epoxy resin composition according to Claim 1, wherein in the formula (III) R means the combination of hydrogen atom and methyl group and (n + 1) : m = 3 : 1. An epoxy resin composition according to Claim 1, wherein in the formula (IV) R is hydrogen atom and n = 1-4.

Inventors: MOGI NAOKI, OHSUGA HIRONORI, SHIMAWAKI HIROSHI, YANAGISAWA KENICHI, MOGI, NAOKI, OHSUGA, HIRONORI, SHIMAWAKI, HIROSHI, YANAGISAWA, KENICHI
Applicants: SUMITOMO BAKELITE CO, SUMITOMO BAKELITE COMPANY LIMITED
Application year: 1989
Main classification: C08G59
IPC codes: C08G59, C08L63