JPH02127417A - Epoxy resin composition - Google Patents

Abstract

PURPOSE:To provide the subject composition composed of a specified silicone- modified epoxy resin, phenolic novolak resin and inorganic filler, excellent in moldability, marking properties, moisture resistance, thermal shock resistance and solderability, having high reliability and suitable for sealing of semiconductors. CONSTITUTION:An objective composition composed of (A) a silicone-modified epoxy resin (hereinafter represented as modified resin) with 95-100 silicone- modification ratio (R) of the formula [A is S/T (S is peak area of silicone compound separated at a position of 0.7-0.9 Rf value in the thin layer chromatography method developed by using organic solvent with <=0.25 solvent strength and silica gel absorbent; T is peak area of cholesterol acetate as standard substance separated at a position of 0.4-0.6 Rf value); B is weight of modified resin in sample solution/weight of standard substance in sample solution; C is silicone component content in modified resin; K is weight of silicone compound corresponding to S/weight of cholesterol acetate corresponding to T] and (B) phenolic novolak resin and (C) an inorganic filler.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention is characterized by improved molding processability (mold stains, resin particles, molding voids,
The present invention relates to a resin composition for semiconductor encapsulation that has excellent properties (deafness), imprintability, moisture resistance, thermal shock resistance, and soldering heat resistance.

(Prior art) In recent years, epoxy resin compositions have been used in large quantities and most commonly for resin encapsulation of semiconductor elements and electronic circuits such as ICs, LSIs, h-run sisters, and diodes due to their characteristics, cost, etc. .

However, as electronic components become more mass-producible, become lighter, thinner, shorter, and more integrated, demands on sealing resins are becoming stricter. has become more strongly demanded than ever before.

Silicone oil, to improve moisture resistance and thermal shock resistance.
Additions of silicone compounds such as silicone rubber, synthetic rubber thermoplastic resins, etc. have generally been carried out.

Even with ordinary epoxy resin compositions that do not contain modifiers, mold stains, resin flakes, molding voids, and poor marking properties tend to occur, but moisture resistance, thermal shock resistance, If a modifier is added to improve solder heat resistance, mold stains, resin flakes, molding voids, and poor marking properties will become worse.

These molding processability (mold stains, resin cracks, molding voids,
The reason why poor mold releasability and marking properties occur is that these modifier components stand out on the surface of the molded product during the molding process.
This is due to poor compatibility between these modifier components and epoxy resins and phenol resins.

In order to improve these problems, it has been proposed to use silicone compounds reacted with epoxy resins or phenol resins (for example, in Japanese Patent Laid-Open No. 6
1-73725, JP-A-62-174222, JP-A-62-212417, etc.).

By using these silicone-modified resins, the embossment of the silicone compound can be suppressed to some extent, resulting in improved moldability and imprintability, and an epoxy resin composition with improved moisture resistance, thermal shock resistance, and soldering heat resistance to some extent. Although I was able to obtain it, I was still not satisfied with it.

The reason for this is that silicone compounds and epoxy resins are compounds that are poorly compatible with each other, and therefore have poor reactivity and have not been able to obtain silicone-modified epoxy resins with high reaction rates.

For this reason, conventionally available silicone-modified epoxy resins contained a large amount of unreacted silicone compounds, making it impossible to obtain one that satisfied moldability and stampability.
Furthermore, the effects of improving moisture resistance, thermal shock resistance, and soldering heat resistance were also insufficient.

As a result of intensive research on these points, we have found that in order to maximize the benefits of silicone-modified epoxy resins, it is necessary to selectively use silicone compounds whose reaction rate with epoxy resins is above a certain value. This invention was made based on the discovery that an excellent resin composition for semiconductor encapsulation, which could not be obtained conventionally, could be obtained.

(Problems to be Solved by the Invention) The purpose of the present invention is to provide excellent molding processability (mold stains, resin flakes, molding voids, mold releasability), stamping properties, moisture resistance, thermal shock resistance, and soldering heat resistance. The object of the present invention is to provide an epoxy resin composition for semiconductor encapsulation that is well-balanced and has excellent reliability.

(Means for Solving the Problems) In order to solve these problems, the present inventors have conducted intensive research and developed chromatography using silica gel as an adsorbent using an organic solvent with a solvent strength of 0.25 or less. The silicone oil obtained by the following formula [I] is 95≦R.
The inventors have completed the present invention by discovering that a silicone-modified epoxy resin in which ≦lOO is optimal as an epoxy resin for semiconductor encapsulation.

R-(1-KA/BC)XI OO... (I)A:
S/T (peak area S of silicone compounds separated into Rf values in the range of 0.7 to 0.9 by thin layer chromatography developed using an organic solvent with a solvent strength of 0.25 or less and silica gel as an adsorbent) Rf value 0.4-0.6
B: Weight of silicone-modified epoxy resin in sample solution /
Weight of standard substance in sample solution C: Silicone component content in silicone-modified epoxy resin (weight of silicone compound added during silicone-modified epoxy resin production reaction) K: Weight of silicone compound corresponding to unit area of silicone compound peak/ Cholesterol acetate weight per unit area of standard substance The silicone-modified epoxy resin used in the epoxy resin composition for semiconductor encapsulation of the present invention has a silicone modification rate R of 9.
It is necessary that 5≦R≦100, and since these silicone-modified epoxy resins have a small amount of unreacted silicone compounds, there is little protrusion of these unreacted silicone compounds on the surface of the molded product, which improves molding processability. In addition, since most of the silicone compound is incorporated into the three-dimensional crosslinked structure of the epoxy resin, the particle size of the silicone becomes extremely small, improving thermal shock resistance and soldering heat resistance. This shows the effect.

In addition, since there is little unreacted silicone compound, the particle size of silicone can be controlled very accurately depending on the chain length and structure of the silicone compound, so material design can be made extremely easily and accurately.

The invention will be explained in detail below.

■Measurement of silicone modification rate R Using a thin layer chromatography automatic detection device tTH-10 manufactured by Diatron Co., Ltd.,
Silica gel was used as the LC, and a nonpolar organic solvent with a solvent strength of 0.25 or less, such as benzene, toluene, or hexane, was used as the developing solvent. Since the unreacted silicone compound is non-polar, it can be developed and separated using a non-polar solvent.

A solution of a silicone-modified epoxy resin in an organic solvent to which cholesterol acetate was added as a standard substance was added to TLC in a few microns.
g ~ 100 μg is spotted and developed with the above developing solvent over a distance of 5 ~ 15 cm.

After drying and removing the developing solvent, the peak area of unreacted silicone compound and the peak area of cholesterol acetate are obtained using a thin layer chromatograph automatic detection device.

Using these area ratios, the modification rate R of the silicone-modified epoxy resin is calculated by formula [I].

In addition, if the modification rate R of a general silicone-modified epoxy resin obtained from conventional literature etc. is measured by these methods,
The modification rate R was 5 to 80%.

■ Synthesis of high modification rate silicone-modified epoxy resin The epoxy resin used as a raw material for the silicone-modified epoxy resin used in the present invention may be any resin as long as it has two or more epoxy groups in one molecule, such as bisphenol A type. Examples include epoxy resin, bisphenol F epoxy resin, phenol novolak epoxy*m, Talezol novolak type epoxy resin, alicyclic epoxy resin, and modified resins thereof, and these epoxy resins can be used in one or two types. The above can be used in combination.

Among these epoxy resins, those with an epoxy equivalent of 150 to 2
50, a softening point of 60 to 130 DEG C., and from which ionic impurities such as Na'' and CI- are removed as much as possible.

Furthermore, the organosiloxane used as one of the raw materials for the silicone-modified epoxy resin of the present invention has a functional group that can react with the above-mentioned epoxy resin, and the functional groups include, for example, an epoxy group, an alkoxy group, a hydroxyl group, an amide group,
Examples include hydrosyl groups, and the molecular structure may be either linear or branched.

Further, the method for synthesizing the silicone-modified epoxy resin in the present invention is not particularly limited, but for example, blocking is performed by reacting an organopolysiloxane having two or more amino groups with some epoxy groups of an epoxy resin. Alternatively, a block adduct can be obtained by a hydrosilylation reaction of an alkenyl group-containing epoxy resin and an organopolysiloxane having two or more hydrosilyl groups under a chloroplatinic acid catalyst in the presence of a solvent. be. In short, no matter which method is used, it is important in the present invention to minimize the amount of unreacted organopolysiloxane, and if necessary, remove these unreacted organopolysiloxanes by washing, extraction, etc. from the obtained reactant. Methods such as removing organopolysiloxane can also be used as appropriate.

These silicone-modified epoxy resins have a reaction rate R of 95
It is necessary that ≦R≦100, and the denaturation rate R is 95
If the epoxy resin composition is less than 10%, the unreacted organosiloxane component has poor compatibility with the epoxy resin composition, has a low surface tension, and generally has a low viscosity, so when the epoxy resin composition is molded at high temperature and high pressure, unreacted parts may appear on the surface of the molded product. This causes failure modes such as oozing of organosiloxane components, oil stains on molded products, mold stains, poor marking properties, and resin flakes. Moreover, unreacted organosiloxane components are also concentrated in the silicone domain in the epoxy resin composition.
The diameter of the silicone domain becomes large. In general, in a resin system that has a morphology of soft polymer islands in a sea of hard polymers, the smaller the particle size of the soft polymer islands, the lower the elastic modulus of the system and the greater the stress reduction effect. Therefore, as the silicone particle size increases, the elastic modulus of the epoxy resin composition increases and the low stress effect decreases, resulting in a decrease in performance (thermal shock resistance) as a resin composition for encapsulating electronic components.

If the reaction rate R is within the range of 95≦R<100, these drawbacks will be greatly improved, and moldability, stampability, and thermal shock resistance will be improved. In addition, mechanical strength and moisture resistance are also improved because the bonding strength at the epoxy/silicone interface is improved. Furthermore, by controlling the composition of the epoxy resin and the composition of the organosiloxane (particularly the molecular chain length), it is possible to control the compatibility between the epoxy and silicone, and to precisely control the silicone particle size. This results in a system that is kept to a minimum and material design is extremely easy.

■Epoxy resin composition using high modification rate silicone-modified epoxy resin The above high modification rate silicone-modified epoxy resin, curing agent, inorganic filler, tertiary amines such as BDMA, imidazole, etc. as required. , 8-diazabicyclo(5,
4,0) Hardening accelerators such as organic phosphorus compounds such as undecene and triphenylphosphine, release agents such as natural waxes and synthetic waxes, flame retardants such as hexabromobenzene, decabromo biphenyl ether, and trioxide, carbon Coloring agents such as black and red iron, silane coupling agents, other synthetic rubbers, silicone compounds, thermoplastic resins, etc. are appropriately added and blended, and after these raw materials are sufficiently mixed using a mixer, etc., they are further heated using a kneader, rolls, etc. The mixture is melt-mixed, cooled and solidified, and then pulverized to obtain an epoxy resin composition.

Examples of the curing agent as the component (b) include phenol nopolak, cresol novolak, and modified resins thereof, which may be used alone or in combination of two or more. Among these phenolic resins, the hydroxyl equivalent is 8.
0-150, softening point 60-120°O, Na3. It is preferable to remove ionic impurities such as carbon as much as possible.

Examples of the inorganic filler as the component (c) include crystalline silica, fused silica, alumina, calcium carbonate, talc, mica, and glass fiber, which may be used alone or in combination of two or more. Among these, crystalline silica or fused silica is particularly preferably used.

(Example) Silicone-modified epoxy resin (A) Shown by structural formula (1) obtained by reacting a reaction product of 0-talesol novolac epoxy resin and o-allylphenol with a silicone compound having HSi groups at both ends. Silicone modified epoxy resin (silicone modification rate R: 97
゜Epoxy equivalent weight 250. Softening point 75°C) m/m+n
Sui wa QΩB, i/ff1M1+imQQ
5, k=190 silicone modified epoxy resin (B
) A silicone-modified epoxy resin represented by the following structural formula [2] (silicone modification rate R: 99°, epoxy equivalent: 252.
Softening point 78°0) m/m+n+1-002i/m+n+
1-0011095 Silicone-modified epoxy resin (C) Silicone-modified epoxy resin represented by the following structural formula [3] (silicone modification rate R: 95°, epoxy equivalent: 260.
Softening point 78°C) m/m+n+imo, 02, i
/I'n+n-n-4i, Of, k@95 Example 1 Silicone-modified epoxy resin (A) 100 parts by weight Phenol nopolak resin (OH equivalent 105. Softening point 100°C) 40 parts by weight Brominated phenol nopolak epoxy Resin (bromine content 30% by weight, epoxy equivalent 280, softening point 71″O)
10 parts by weight Fused silica 530 parts by weight Antimony trioxide 20 parts by weight Silane coupling agent 3 parts by weight triphenylphosphine 4 parts by weight Carnauba wax The mixture was kneaded, cooled, and then crushed into tablets to obtain the epoxy resin composition for semiconductor encapsulation of the present invention.

The stain resistance and resin spacing of this material were determined using a transfer molding machine (molding conditions: mold temperature 175°C, curing time 2 minutes), and the resulting molded product was cured after 17560.4 hours to form a package. Internal voids, imprintability, thermal shock resistance, moisture resistance, and soldering heat resistance were evaluated.

The results are shown in Table 1.

Example 2 An epoxy resin composition for semiconductor encapsulation was obtained in the same manner as in Example 1 except that the silicone-modified epoxy resin (A) in Example 1 was changed to silicone-modified epoxy resin (B). was evaluated.

The results are shown in Table 1.

Example 3 An epoxy resin composition for semiconductor encapsulation was obtained in the same manner as in Example 1, except that the silicone-modified epoxy resin (A) in Example 1 was changed to silicone-modified epoxy resin (C), and the same procedure as in Example 1 was carried out. was evaluated.

The results are shown in Table 1.

Comparative Example 1 An epoxy resin composition for semiconductor encapsulation was obtained in exactly the same manner as in Example 1 except that one with a silicone modification rate R of 79 was used in Example 1, and the same evaluation was performed.
Shown in the table.

Comparative Example 2 An epoxy resin composition for semiconductor encapsulation was obtained in exactly the same manner as in Example 1, except that one with a silicone modification rate R of 52 was used in Example 1, and the same evaluation was performed.
Shown in the table.

Comparative Example 3 An epoxy resin composition for semiconductor encapsulation was obtained in exactly the same manner as in Example 2, except that one with a silicone modification rate R of 74 was used in Example 2, and the same evaluation was performed.
Shown in the table.

Comparative Example 4 An epoxy resin composition for semiconductor encapsulation was obtained in exactly the same manner as in Example 3, except that one with a silicone modification rate R of 32 was used in Example 3, and the same evaluation was performed.
Shown in the table.

(Hereafter under The rest White) *l Zero 2 *3 *4 *5 *6 Judgment is based on the number of molded shots until mold fogging occurs.

Measure the length of the resin pad at the bent part of the molded product obtained.

Use the molded product of the 10th shot, and after stamping it, stick cellophane tape on it. Judgment is made by the number of stamps removed when the cellophane tape is removed. The table shows the number of molded products whose seals were peeled off out of 50 molded products.

20 molded products (post-cured at 175°C + 8 hours) were subjected to a temperature cycle test (150 to -65°C), 500 cycles were performed, and the number of cracks was determined. The table shows the number of cracks in 20 molded products.

A moisture resistance test was conducted for 1000 molded products (post-cured at 175°C + 8 hours) under high-pressure steam at 120°C for 1000 hours to determine the number of defective products. The table shows the number of defective pieces out of 100 pieces.

After processing 16 molded products (post-curing 175° 0.8 Hrs) under 85° 085% steam for 72 Hrs, 280
The molded product was immersed in a solder bath at ℃ for 10 seconds and determined by the number of molded products that developed cracks. The table shows the number of cracks among 16 molded products.

(Effects of the Invention) The epoxy resin composition for semiconductor encapsulation of the present invention has excellent heat cycle resistance, solder stress resistance, and moisture resistance, and is a low stress composition. When used for stopping, covering, insulating, etc., it is possible to obtain products with extremely high M failure, especially in highly integrated large chip ICs mounted on surface mount packages.

Claims (1)

[Claims] (1) (A) A silicone-modified epoxy resin whose silicone modification rate R calculated from the following formula [I] is 95≦R≦100 = (1-KA/BC)×100... [I] A:S
/T (Rf value 0.7 to 0.9 by thin layer chromatography using an organic solvent with a solvent strength of 0.25 or less and developing with silica gel as an adsorbent)
Ratio of the peak area S of the silicone compound separated into the range of Rf value and the peak area T of the standard substance cholesterol acetate separated into the range of Rf value 0.4 to 0.6) B: Silicone modified epoxy resin in the sample solution Weight of /
Weight of standard substance in sample solution C: Silicone component content in silicone-modified epoxy resin (weight of silicone compound added during silicone-modified epoxy resin production reaction) K: Weight of silicone compound corresponding to unit area of silicone compound peak/ Cholesterol acetate weight per unit area of standard substance (b) Phenol noporac resin (c) Epoxy resin composition containing an inorganic filler as an essential component.