KR930001989B1 - Epoxy resin composition for encapsulating semiconductor - Google Patents

Abstract

The epox rsin compsn. comprises (a) 10-30 wt. parts of a cresol (or phenol) novolak epoxy resin having 170-240 epoxy equivalent and 60-110 deg.C softening point, (b) 5-20 wt. parts of a phenol (or cresol) movolak resin having 70-110 deg.C softening point, (c) 60-80 wt. parts of an inorganic filler, (d) 0.1-10 wt. parts of a polydimethyl siloxane-silicon oil, (e) 0.1-5 wt. parts of a hume silica having 0.01-0.05 μm particle size and 100-300 m2/g surface area, and (f) 0.01-5 wt. parts of a thermoplastic phenoxy resin of formula (I) having 25000-35000 molecular wt. In (I), n = 82-123; R1=H, hydroxyl, phenoxy or glycidyl bisphenoxy. The epoxy resin has a good heat resistance and crack resistance.

Description

Epoxy Resin Compositions for Semiconductor Sealing

The present invention relates to an epoxy resin composition for sealing semiconductor devices, and particularly, excellent in high temperature heat resistance and crack resistance, sufficiently improved moldability, which is a characteristic of melt molding, and low reliability with minimal mold contamination. It relates to a low stress epoxy resin composition for semiconductor sealing.

Conventionally, hermetic seals such as glass, metal and ceramic have been used for sealing semiconductor devices such as transistors, integrated circuits (ICs), highly integrated circuits (LSIs), and ultra-high integrated circuits (VLSIs), but they are expensive and are required for mass production. Since they are not suitable, they are rarely used except for some military applications. Recently, thermosetting resins such as epoxy, silicone, phenol, phthalate, and amide are used instead of these materials. Among them, epoxy resins are widely used as components, adhesives, and building materials for electric and electronic materials because they have superior physical properties such as heat resistance, electrical properties, dimensional stability, and adhesion.

In particular, in recent years, miniaturization, thinning, and weight reduction of electric and electronic components have been progressed due to the remarkable development of semiconductor design technology, microfabrication technology, and process management technology. Epoxy resins are widely used as sealing materials for such multifunctional and highly functional semiconductor devices.

The sealing material of semiconductor device should be excellent in heat resistance, moisture resistance, reliability and mechanical strength, and should show moderate hardness not to wear out the mold, and small internal stress due to small difference in coefficient of thermal expansion with internal seal during cooling cycle. In order to minimize the occurrence of heat, and to prevent heat generation of the semiconductor device, it is desirable to have excellent thermal conductivity, and heat resistance and crack resistance due to miniaturization and thinning of electrical and electronic components are important.

In addition to the above-described required characteristics, semiconductor sealing materials excellent in fluidity and formability are desired. If the fluidity is too high, resin flows into a small gap of the mold during molding, causing flash to deteriorate workability. If the flash generated on the lead wire of a semiconductor component is not removed, If the process is defective, and if the fluidity is too small, problems such as bending or cutting the bond wire or unfilled during molding. Therefore, there is a need for a highly reliable semiconductor sealing resin composition having optimum fluidity, not contaminating a mold, minimizing the generation of flash, minimizing internal stresses, and having excellent high temperature thermal shock resistance.

Epoxy resin compositions used for the sealing of conventional semiconductor devices have tried to improve the thermal shock resistance by the type and amount of epoxy resins, the type and amount of catalysts, and rubber-based compounds having excellent thermal shock resistance, but problems of fluidity and moldability occur. In addition, the resin composition for semiconductor encapsulation, which improves fluidity and moldability by controlling the type, particle size, particle size distribution, and the like of the inorganic filler, has lowered reliability such as moisture resistance and heat resistance.

In the compositions described in Japanese Patent Application Laid-Open Nos. 53-144958, 56-122823, 58-174416, 61-133222, 58-47014, oils and rubbers such as butadiene-based rubbers and silicone-based rubbers are used as heat shock agents. However, this can improve the thermal shock resistance, but the fluidity and in particular the mold contamination and flash problems could not be completely solved, and Japanese Patent Laid-Open Nos. 62-10159, 61-221222, 61-254619 In the composition described in the present invention, the fluidity and the flash reduction were somewhat improved by controlling the type, particle size, and particle size distribution of silica, but problems of thermal shock resistance and moisture resistance could not be solved.

In addition, in the composition described in Japanese Patent Application Laid-Open No. 62-22822, PBT is used as a heat resistance agent, and thermal shock resistance and mold contamination can be improved to some extent, but problems of flash generation and fluidity decrease are also caused. Because the processing temperature of PBT is too high, it is not possible to expect a uniform dispersion, and there is a fear of deterioration in mechanical strength, etc., and it has excellent heat resistance and crack resistance, and moldability and reliability of increased fluidity and flash reduction, which are characteristics of melt molding. It is difficult to use this excellent product for semiconductor element sealing.

As a result of the intensive efforts to improve such problems, the inventors have improved the thermal shock resistance and crack resistance to maintain low stress, and prevent the deterioration of fluidity and the occurrence of flash, mold contamination, and bonding wire warping. The inventors have invented an epoxy resin composition for low stress semiconductor sealing that satisfies required characteristics such as strength.

That is, the present invention

(1) 10 to 30 parts by weight of a cresol novolac epoxy resin or phenol novolac epoxy resin having an epoxy equivalent of 170 to 240 and a softening point of 60 to 110 ° C,

(2) 5 to 20 parts by weight of a phenol novolak resin or cresol novolak resin having a softening point of 70 to 110 ° C,

(3) 60 to 80 parts by weight of inorganic filler,

(4) 0.1 to 10 parts by weight of a polydimethyl siloxane silicone oil substituted with a methyl group, an epoxy group, an amine group, a hydroxyl group or a carboxyl group in the terminal or molecular chain,

(5) 0.1 to 5 parts by weight of fume silica having a particle size of 0.01 to 0.05 μm and a specific surface area of 100 to 300 m ² / g,

(6) 0.01 to 5 parts by weight of thermoplastic phenoxy resin

It relates to a resin composition for semiconductor encapsulation comprising a.

The present invention is described in detail as follows.

Cresol novolac epoxy resin and phenol novolac epoxy resin of component (1) used in the present invention have an epoxy equivalent of 170 to 240, and a softening point of cresol novolac epoxy resin or phenol novolac epoxy. The resin contains at least three or more epoxy groups in one molecule, and the concentration of hydrolyzable chlorine ion is 200 ppm or less. If epoxy equivalent is 240 or more, sufficient heat resistance and mechanical strength, which are advantages of epoxy resin, cannot be obtained due to reduction of crosslinking density. If softening point is 110 ° C or higher, problems of melt mixing process will occur, resulting in poor uniform dispersion and reliability. Difficulty in the production of these products, and also the difficulty in sealing work due to the deterioration of fluidity. If the softening point is less than 60 ℃ it is not good because the flash generation is significantly increased. In addition, when the concentration of hydrolyzable chlorine ion is 200ppm or more, moisture resistance is poor. Bisphenol types other than cresol novolac epoxy resins or phenol novolac epoxy resins, i.e., bisphenol A epoxy resins and bisphenol F epoxy resins, have a low viscosity liquid phase when the epoxy equivalent is 240 or less, which significantly reduces the flash generation suppression characteristics. The heat resistance at the time of shaping | molding also falls. In order to impart flame retardance to the molding material of the cresol novolac epoxy resin or the phenol novolac epoxy resin of the component (1), it is preferable to generally use 10 to 30% by weight of a brominated epoxy resin in all epoxy resins. Here, epoxy equivalent and softening point are not restrict | limited, The well-known thing used conventionally can be used.

Component (2) used in the present invention is a curing agent of an epoxy resin mainly containing the component (1) as a novolac resin such as a phenol novolak resin or a cresol novolak resin containing two or more hydroxyl groups in a molecule. The softening point of 70-110 degreeC is used. If the softening point other than the novolak-based resin curing agent is lower than 70 ° C., flash generation is remarkable, and if it is higher than 110 ° C., the fluidity is worsened, which causes difficulty in sealing work.

Inorganic fillers of component (3) used in the present invention include silicon oxide, calcium carbonate, alumina, pulverized molten silica, spherical fused silica, crystalline silica, glass, magnesite, gypsum, graphite, cement, iron carbonyl, tar , Mica, silica sand, carotene, aluminum hydroxide, asbestos, and the like can be used by mixing two or more kinds. Preferably, 60 to 80% by weight of the crystalline silica, pulverized fused silica, and spherical fused silica having a median particle size of 5 to 40 µm and spherical fused silica are used.

When using 60 wt% or less, the coefficient of thermal expansion increases, so that the reliability of heat resistance, crack resistance, moisture resistance, etc. is deteriorated in the case of semiconductor sealing devices. Warping or cutting occurs, and in severe cases, sealing becomes impossible.

The silicone oil of the component (4) used in the present invention is a component used to improve the thermal shock resistance and crack resistance, but has an excellent effect on low stress, but when used in a certain amount or more, mold contamination and flash generation are remarkable. Therefore, the amount of use is limited. The silicone oil used may be a polydimethylsiloxane-based silicone oil which is substituted with a methyl group, an epoxy group, an amine group, a hydroxyl group, a carboxyl group, or the like in the terminal or molecular chain. The amount used is 0.1 to 10 parts by weight, and mold contamination And 0.1 to 3.0 parts by weight are preferable in consideration of the flash generating surface. When the amount of the silicone oil used is 0.1 parts by weight or less, the role of stress relaxation of the thermal shock resistance and crack resistance improvement cannot be sufficiently sufficient. When the amount of the silicone oil is more than 5 parts by weight, the fluidity is lowered and the generation of the flash is remarkable. Mold contamination occurs badly and cannot be used. In addition, even in the compounding method, in terms of economics, the single injection method is preferable, but when it is added alone, silicon oil is separated from each raw material during transfer molding, and mold contamination occurs very seriously, and the occurrence of flash is significantly increased. It is not possible to add it alone, and it is preferable to use it after cooling it for 2 to 4 hours (pre-mixing) between epoxy resin and 120-150 degreeC. If it is kneaded at 120 ° C. or less, the epoxy resin is not sufficiently melted in a short time, so that it is difficult to uniformly disperse and disperse for a long time. In addition, the melt dispersion at 150 ℃ or more can not be used because the epoxy resin is deteriorated, resulting in degradation of coloration, poor heat resistance, mechanical strength and the like.

The (5) component fume silica used in the present invention is sufficiently improved thermal shock resistance and fluidity by using the silicone oil of the (4) component, but the flash generation problem is not completely solved, so the present invention completely solves such a flash problem. Unlike silica, which is a component (3), it is a colloidal silicon dioxide produced by hydrolysis by burning silicon tetrachlorine vapor with hydrogen and oxygen, and is also referred to as pyrogenic silica.

Unlike natural silica, which is component (3), this component is called fume silica and has a tendency to form defects when it is separated, and is selectively formed or destroyed depending on the presence of external force. Has a structure. In addition, hydroxyl groups adhere to the silicon atoms on the particle surface during the formation of fume silica, which makes the surface of the fume silica hydrophilic, allowing hydrogen bonding with other raw materials, resulting in the control of free flow characteristics. It has excellent characteristics, and has a particle diameter of 0.01 to 0.05 μm, specific surface area in the range of 100 to 300 m ² / g, and is X-ray amorphous. Preferably, 0.1 to 5% by weight of particles having a particle diameter of 0.012 to 0.02 µm are satisfactory to satisfy the characteristics of the present invention. If the particle diameter is smaller than 0.01 μm, problems such as bending or cutting of the bonding wire during molding due to the viscosity increase may occur. If the particle diameter is larger than 0.05 μm, the flash generation suppressing ability may be significantly reduced. In addition, if more than 5% by weight of the total composition is added, the viscosity increase is so large that the free fluidity is remarkably lowered, so that the bonding wire is bent or cut during molding, and in severe cases, the sealing is impossible. And the ability to improve physical properties of the flash generation suppression.

The thermoplastic phenoxy resin as the component (6) of the present invention is prepared from epichlorohydrin and 2,2-bis (4-hydroxyphenol) propane in the same manner as in US Pat. No. 3,356,646 and has a molecular weight of It is a substance which has a structure as follows between 25, 000 and 35, 000.

Wherein n is an integer between 82 and 123, and R ₁ may be hydrogen, hydroxyl, phenoxy or glycidyl bisphenoxy group. When the thermoplastic phenoxy resin is used simultaneously with the components (1), (2), (3), (4) and (5) of the present invention, it does not generate mold contamination and flash and gives flexibility to the resin structure. It has been found that it is an excellent low stress epoxy resin for sealing semiconductors by lowering the flexural modulus to improve thermal shock resistance, improving crack resistance and thermal shock resistance, and improved moisture resistance.

The amount thereof is preferably 0.01 to 5% by weight, more preferably 0.5 to 4% by weight, based on the weight of the resin composition. If the amount is less than 0.01% by weight, the dispersion in the epoxy resin is not sufficient, so that the effect of improving the thermal shock resistance cannot be expected. If the amount is more than 5% by weight, the fluidity is rapidly decreased and the mold contamination is bad, which is not preferable.

The epoxy resin composition for semiconductor element sealing of the present invention contains the above-mentioned components (1), (2), (3), (4), (5) and (6) as essential components, and the curing speed during molding Imidazole, 2-methyl imidazole, 1, 2-dimethylimidazole, 2-phenylimidazole, 2-ethylimidazole, 2-methyl-4-ethylimidazole and triphenyl for the purpose of promoting Organic phosphines such as phosphine, tributylphosphine, triphenylboron, dimethylphosphine, dibutylphenylphosphine, methyldiphenylphosphine, triethanolamine, tetramethylhexanediamine, triethyleneamine, dimethylaniline, 1, Tertiary amines and quaternary ammoniums such as 8-diaza-bicyclo (5, 4, 0) undecene-7, pyridine, dodecyltrimethyl ammonium chloride, cetyltrimethyl ammonium chloride, stearyl trimethyl ammonium chloride At least one or more of the salts is used in an amount of 0.1 to 1% by weight based on the total weight of the composition. Moreover, it is preferable to mix | blend well-known additives, such as inorganic flame retardant aids, such as antimony trioxide, a coloring agent, a mold release agent, a coupling agent, an antidegradation agent, with 10 weight% or less.

The epoxy resin molding material for semiconductor encapsulation of the present invention is obtained by uniformly mixing each component required by using a mixing apparatus such as a roll and a kneader, and the specific operation method such as the mixing procedure is particularly limited. There is no Preferably, the silicone oil as the component (4) is pretreated with a cresol novolac epoxy resin, a phenol novolac epoxy resin or a phenol novolac resin, and is preferably added as a solid phase.

When the inventors of the present invention actually sealed various semiconductors by the transfer molding method using the epoxy resin composition of the present invention, the present invention satisfies general characteristics such as moisture resistance, mechanical strength, and thermal conductivity, and thus excellent thermal shock resistance and crack resistance, It was found that there is an excellent effect on the reliability of moisture resistance, optimum fluidity, suppression of flash generation and mold contamination prevention.

Hereinafter, the effect of this invention was demonstrated to an Example and a comparative example. The cresol novolac epoxy resins used in the examples and comparative examples were epoxy equivalent 203 and a softening point of 70 ° C., and brominated phenol novolac epoxy resins had an epoxy equivalent of 270 and a softening point of 92 ° C., and a phenol novolac epoxy resin of 106, The softening point is 100 ° C.

Inorganic fillers used in the present invention were used alone or in combination as pulverized fused silica, spherical fused silica, and crystalline silica, having a median particle size of 10 to 20 µm.

Example 1

The phenoxy resin A of Table 1 is used for cresol novolak epoxy resin and brominated phenol novolak resin, and the fume silica A of Table 2 is used here, 2-methylimidazole, carnauba wax, and antimony trioxide , Carbon black, coupling agent, and spherical pulverized molten silica are blended in the amounts shown in Table 4, and heat kneaded between two rolls at 85 to 95 ° C. to be pulverized to a certain particle size for convenient use. An epoxy resin composition was obtained, and the results are shown in Tables 4 and 5.

Example 2

The phenoxy resin A of Table 1 was used for cresol novolak epoxy resin and phenol bromide phenol novolak resin, and the fume silica A of Table 2 was used here, the silicone oil B of Table 3 was used here, and 2-methyl Midazole, carnauba wax, antimony trioxide, carbon black, coupling agent, and spherical pulverized molten silica are blended in the amounts shown in Table 4, and heat-kneaded between two rolls at 85 to 95 ° C for convenient grinding and use. It was compressed to such that the epoxy resin composition for semiconductor sealing of the present invention was obtained. The results are shown in Tables 4 and 5.

Example 3

Except for using fume silica B instead of fume silica A and the same as in Example 1, the results are shown in Tables 4 and 5.

Example 4

Except for using fume silica B instead of fume silica A and the same as in Example 2, the results are shown in Tables 4 and 5.

Example 5

Except for using phenoxy resin B instead of phenoxy resin A, the same as in Example 1, the results are shown in Tables 4 and 5.

Example 8

Except for using phenoxy resin B instead of phenoxy resin A and the same as in Example 2, the results are shown in Tables 4 and 5.

Example 7

Except for using fume silica B instead of fume silica A and the same as in Example 5, the results are shown in Tables 4 and 5.

Example 8

Except for using fume silica B instead of fume silica A and the same as in Example 6, the results are shown in Tables 4 and 5.

Example 9

Except for changing the amount of the phenoxy resin A was used as in Example 1, the results are shown in Tables 4 and 5.

Example 10

Except for changing the amount of the phenoxy resin B was used as in Example 1, the results are shown in Tables 4 and 5.

Comparative Example 1

Except that phenoxy resin A was not used, and the same as in Example 1, the results are shown in Tables 4 and 5.

Comparative Example 2

Except that Hume Silica A was not used, the same as in Example 1, the results are shown in Tables 4 and 5.

Comparative Example 3

Except that silicone oil A was not used, it was the same as in Example 1, the results are shown in Tables 4 and 5.

[Comparative Example 4]

Except for not using the phenoxy resin A and fume silica A and the same as in Example 1, the results are shown in Tables 4 and 5.

[Comparative Example 5]

Except for not using the phenoxy resin A and silicone oil A and the same as in Example 1, the results are shown in Tables 4 and 5.

Comparative Example 6

Except for not using fume silica A and silicone oil A, the same as in Example 1, the results are shown in Tables 4 and 5.

Comparative Example 7

Except for not using the phenoxy resin A, fume silica A and silicone oil A and the same as in Example 1, the results are shown in Tables 4 and 5.

TABLE 1

TABLE 2

TABLE 3

TABLE 4

TABLE 5

: 보통, × : 불량*; 0: good,

: Normal, ×: Poor

In addition, the spiral flow measuring method of the Example and comparative example of this invention is a value measured according to EMMI1-66 (Epoxy Molding Material Institute: Society of Plastic Industry) using a spiral mold. The epoxy resin composition is good when the measured value is 70 to 120 cm, and more preferably, it should have a spiral flow value of about 80 to 110 cm.

Flash measurement method of the present invention using a flash measuring mold having a gap of 76μm, 50μm, 12μm, 6μm length of the resin leaked into the 25μm gap which is the average gap after the transfer molding at the mold temperature 175 ℃, transfer pressure 70kg / cm ² The value is indicated.

The internal stress measurement methods of the present invention include a steel ring method and a piezo method. Since the steel ring method is more effective for measuring the stress of the resin itself, the steel ring method is used in the present invention. A strain gage is attached to the inner surface of an iron cylinder (diameter 20 mm, thickness 1 mm, height 20 mm) to form an outer surface with a resin so that its thickness is 20 mm. After transfer molding at 175 ° C., the stress generated in the circumferential direction while obtaining a temperature down to 25 ° C. is obtained as the deformation amount of the steel ring.

Heat shock resistance measurement method of the present invention after transfer molding the lead frame of the 16-pin IC (Island) size of 4 × 7.5mm for 2 minutes at 175 ℃ 70kg / cm ² The molded article is immersed in a liquid of -196 ° C and a liquid of 260 ° C for 30 seconds in one cycle, and the number of cracks is generated on the surface of 40 molded bodies.

The mold contamination occurrence measurement method of the present invention is a one-time transfer molding of a lead frame of a 16-pin IC having an island size of 4 × 7.5 mm at a mold having 600 cavities at 175 ° C. and 190 jg / cm ² . ), And the degree of staining on the surface of the molded product was visually determined, and it was good that there was almost no stain, and only a small amount was usually markedly defective.

Claims (6)

(a) 10 to 30 parts by weight of a cresol novolac epoxy resin or phenol novolac epoxy resin having an epoxy equivalent of 170 to 240, a softening point of 60 to 110 ° C, and (b) a phenol novolac resin or cresolno having a softening point of 70 to 110 ° C. 5 to 20 parts by weight of a volac resin, (c) 60 to 80 parts by weight of inorganic filler, (d) 0.1 to 10 parts by weight of polydimethyl siloxane silicone oil, (e) 0.1 to 5 parts by weight of fume silica, (f) thermoplastic An epoxy resin composition for semiconductor encapsulation, comprising phenoxy resin 0.01 to 5 parts by weight. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the epoxy resin (a) contains at least three epoxy groups in one molecule. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the inorganic filler is silicon oxide, calcium carbonate, pulverized fused silica, spherical fused silica, crystalline silica, alumina, mica. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the polydimethyl siloxane silicone oil is substituted with an ethyl group, an epoxy group, an amine group, a hydroxyl group, or a carboxyl group in the molecular chain. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the fume silica has a particle size of 0.01 to 0.05 µm and a surface area of 100 to 300 m ² / g. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the thermoplastic phenoxy resin is represented by the following general formula having a molecular weight of 25, 000 to 35,000.

Wherein n is an integer from 82 to 123, R ₁ is hydrogen, hydroxyl, phenoxy, glycidyl bisphenoxy group.