JPH02251519A - Epoxy resin composition - Google Patents

Abstract

PURPOSE:To obtain an epoxy resin for sealing semiconductor which has excellent fabricability. marking properties, moisture resistance and soldering heat resistance by using a silicone-modified epoxy resin having a specific silicone modification rate and a silicone-modified phenolic resin. CONSTITUTION:The subject epoxy resin composition is obtained by adding a silicone-modified epoxy resin having R in the range of 95 <=R <=100 in the equation (A is the peak area of silicone fraction which is separated at 0.7 Rf value/the peak area of the standard substance separated at 0.4 to 0.6 Rf value, namely cholesterol acetate; B is the weight of the silicone-modified resin/the weight of the standard substance; C is silicone component content in the silicone- modified resin; K is the weight of silicones corresponding to the unit area of the silicone compound peak/the weight of the cholesterol acetate, the standard substance), to a silicone-modified phenolic resin.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is applicable to molding processability (mold stains, resin flakes, molding voids, mold releasability), imprintability, moisture resistance, thermal shock resistance, and soldering heat resistance. The present invention relates to a resin composition for semiconductor encapsulation which contains an excellent high modification rate silicone-modified epoxy resin and a high modification rate silicone-modified 7-enol resin as main components.

(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, Lancisters, 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 rubbers, thermoplastic resins, etc. have generally been carried out.

Even with ordinary epoxy resin compositions without the addition of modifiers, defects such as mold stains, resin cracks, and imprintability tend to occur easily, but it can improve moisture resistance, thermal shock resistance, and soldering heat resistance. Therefore, if a modifier is added, problems such as mold staining, resin fringing, molding voids, and poor sealability will become worse.

These molding processability (stains, resin particles, molding voids,
Defects in mold releasability and imprintability occur because these modifier components stand out on the surface of the molded product during the molding process, and the interaction between these modifier components and the epoxy resin and phenol resin causes This is due to poor compatibility.

In order to improve these problems, it has been proposed to use a silicone compound reacted with a phenol resin or an epoxy resin (for example, in JP-A 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 molding processability 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 or phenol resins are compounds that have poor compatibility with each other, so their reactivity is poor and a silicone-modified resin with a high reaction rate has not been obtained.

For this reason, conventionally obtained silicone-modified resins contain a large amount of unreacted silicone compounds, making it impossible to obtain products that satisfy molding processability and stamping properties, as well as moisture resistance, thermal shock resistance, and soldering heat resistance. The effect of improving sex was also insufficient.

As a result of intensive research on these points, we have found that in order to maximize the benefits of silicone-modified resins, it is necessary to selectively use compounds whose reaction rate between silicone compounds and epoxy resins or phenolic resins is above a certain value. This invention was made based on the discovery that an extremely superior 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), imprintability, moisture resistance, thermal shock resistance, and soldering heat resistance. The object of the present invention is to provide a 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 thin layer chromatography using an organic solvent with a solvent strength of 0.25 or less and developing silica gel as an adsorbent. The silicone modification rate determined by the following formula (1) is 95.
The present invention was completed by discovering that a composition comprising a silicone-modified epoxy resin and a silicone-modified phenol resin in which ≦R≦100 is optimal as an epoxy resin composition for semiconductor encapsulation.

R= (1-KA/BC)Xl 00... (1)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) and Rf value 0.4~0
．． 6) B: Weight of silicone-modified resin in sample solution/weight of standard substance in sample solution C: Silicone component content in silicone-modified resin (Weight of silicone compound added during silicone modified resin production reaction) K: weight of silicone compound corresponding to unit area of silicone compound peak/weight of cholesterol acetate to unit area of standard substance.

The high modification rate silicone-modified epoxy resin or phenol resin used in the present invention must have a silicone modification rate R of 95≦R≦100, and these silicone-modified epoxy resins or phenol resins must be free of unreacted silicone compounds. Because of the small amount of unreacted silicone compounds, there is little protrusion of unreacted silicone compounds on the surface of the molded product, which does not deteriorate molding processability or stamping properties.Moreover, most silicone compounds have a three-dimensional crosslinked structure of epoxy resin and phenol resin. As a result, the particle size of silicone becomes extremely small, resulting in improved strength, thermal shock resistance, and soldering heat resistance.

In addition, there is less unreacted silicone compound.I: The particle size of the silicone can be controlled very accurately depending on the chain length and structure of the silicone compound, so material design can be done extremely easily and accurately. .

In particular, by introducing silicone into both the epoxy resin and the phenolic resin used as a hardening agent, it is possible to design materials that are superior in terms of the amount of modification, particle size, and dispersibility throughout the composition. I can do it.

The details will be explained in more detail below.

■Measurement of silicone modification rate R Using a thin layer chromatography automatic detection device TH-10 manufactured by Diatron Co., Ltd.,
Silica gel was used as C, and a nonpolar organic solvent with a solvent strength of 0.25 or less, such as benzene, toluene, hexane, etc., 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 few pg"lo of an organic solvent solution of silicone modified resin to which cholesterol acetate was added as a standard substance was subjected to TLC.
Spot 0 μg and add 5 to 15 μg of it with the above developing solvent.
CM is expanded.

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 resin is calculated by formula [I].

In addition, if the modification rate R of general silicone modified resin obtained from conventional literature etc. is measured by these methods, the modification rate R
was 15-85%.

■Synthesis of high modification rate silicone-modified epoxy resin As a raw material for the silicone-modified epoxy resin used in the present invention, any epoxy resin can be used as long as it has two or more epoxy groups in one molecule, such as bisphenol A type. Epoxy resins, bisphenol F type epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins, alicyclic epoxy resins, and modified resins thereof, etc., are listed, and these epoxy resins can be used singly or in combination of two or more types. It can be used. Among these epoxy resins, epoxy equivalents of 150 to 250,
It is preferable to have a softening point of 60 to 130°0 and to remove ionic impurities such as Na'' and CI- 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 examples of the functional group include an epoxy group, an alkoxy group, a hydroxyl group, an amino group,
Examples include hydrosyl groups, and the molecular structure may be either linear or branched.

Furthermore, the method for synthesizing the silicone-modified epoxy resin in the present invention is not particularly limited, but for example, an organopolysiloxane having two or more amino groups is reacted with some epoxy groups of an epoxy resin to form a block. Synthesis methods include forming an adduct, or obtaining a block adduct through 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. There is. In short, no matter which method is used, it is important in the present invention to minimize the amount of unreacted organopolysiloxane.
It is also possible to appropriately remove these unreacted organopolysiloxanes by methods such as extraction.

An example of the method for synthesizing the high modification rate silicone-modified epoxy resin of the present invention is shown below.

After heating and stirring 100 parts by weight of phenol novolac epoxy to reduce the water content to 0.01% by weight or less by stirring, add 3 parts by weight of 0-allylphenol and 1% as a catalyst at normal pressure. .1 part by weight of 8-diazabicyclo(5,4,0)undecene-7 (DBU) is melted and reacted. DB by reducing water content
U was not deactivated and O-allylphenol reacted 100% (confirmed by gas chromatography).

100 parts by weight of the obtained allylated epoxy and H-
25 parts by weight of a dimethyl silicone compound having a 5i group,
After heating and stirring 100 parts by weight of toluene to perform azeotropic dehydration for 1 hour, 0.1 part by weight of an isopropyl alcohol solution of chloroplatinic acid (1% by weight) was added dropwise and refluxed to obtain a silicone-modified epoxy resin. Ta.

By performing sufficient dehydration in the first and second reactions, the silicone modification rate R becomes 95 or more. Especially when the first stage reaction is not carried out sufficiently, unreacted O-allylphenol is
It is present in an amount of 0 to 35% and reacts with the H-5i group of silicone oil during the hydrosilyl reaction in the subsequent reaction, resulting in a silicone modification rate R of less than 95%, resulting in improved moldability, thermal shock resistance, and soldering heat resistance of the resin composition. Sexuality decreases.

■Synthesis of high modification rate silicone-modified epoxy resin Phenol resins used as raw materials for the silicone-modified phenol resin used in the present invention include phenol novolac resins, cresol novolac resins, and modified resins thereof, and these phenol resins can be used in combination of one or two types. It is also possible to use a mixture of more than one species.

Among these phenolic resins, those with a hydroxyl equivalent of 80 to
150, softening point is 60-120℃, Na'', CI
It is preferable to remove ionic impurities such as - as much as possible.

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

The method for synthesizing the silicone-modified phenolic resin of the present invention is not particularly limited, but examples include reacting an organopolysiloxane having two or more epoxy groups with a phenolic resin to form a block adduct; There is a synthesis method in which a block adduct is obtained by a hydrosilylation reaction of an alkenyl group-containing phenol resin and an organopolysiloxane having two or more hydrosilyl groups in the presence of a solvent under a chloroplatinic acid catalyst. 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.

To give one example of the method for synthesizing the silicone-modified phenol novolak resin of the present invention, the phenol novolak resin 100 has a content of unreacted phenols of 3% by weight or less.
3 to 3 to γ-glycidoxypropyl groups in weight part and 1 molecule
Triphenylphosphine or l,8-diazabicyclo(5,4
,0) Undecene-7 (DBU) is used as a catalyst and is obtained by reacting at a reaction temperature of 100 to 180°C for 2 hours or more.

Unreacted phenols in phenol novolac are 3 i%
If it exceeds this, the reaction products of unreacted phenols and organosiloxane will increase, and the silicone modification rate R will be 95%.
It will fall below.

If the number of γ-glycidoxyprobyl groups in the organopolysiloxane is 2 or less, the number of functional groups is small and the reaction with the phenol novolac does not occur sufficiently, and if it is 8 or more, gelation tends to occur, so the number of functional groups is It is necessary to have 3 to 7 pieces.

If the amount of organopolysiloxane blended is less than 10 parts by weight with respect to 100 parts by weight of phenol novolac, flexibility tends to be insufficient, and if it exceeds 40 parts by weight, unreacted organopolysiloxane remains, resulting in silicone modification. rate is below 95%.

As a solvent, a boiling point of 80-1 with moderate compatibility with both phenol novolak and organopolysiloxane is recommended.
Alcohols at 80°0 are optimal.

As a catalyst, organic phosphines and tertiary amines have the best reactivity, and among them, triphenylphosphine and DBU are preferably used.

The reaction temperature must be 100 to 180°C; if it is below 100°C, the reaction will be insufficient, and if it is above 180°C, gelation will tend to occur.

A reaction time of 2 hours or more is required; if the reaction time is less than 2 hours, the reaction will be insufficient and the silicone modification rate will fall below 95%.

In the silicone modified resin used in the present invention, it is necessary that the modification rate R is 95≦R≦100, and if the modification rate R is less than 95, unreacted organosiloxane components will be contained when used as a resin composition for semiconductor encapsulation. has poor compatibility with epoxy resins, has a low surface tension, and generally has a low viscosity. Therefore, when this resin composition is molded at high temperature and pressure, unreacted organosiloxane components ooze from the surface of the molded product, causing oil in the molded product. This causes failure modes such as stains, mold stains, poor imprintability, and resin flakes, and also causes a decrease in strength and hardenability. Moreover, the unreacted organosiloxane component is
Since it also concentrates in the silicone domain part of the 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 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. Furthermore, since the bonding strength at the epoxy resin/silicone or phenol resin/silicone interface is improved, mechanical strength and moisture resistance are also improved compared to when a modifier component is added.

Furthermore, by controlling the composition of the phenolic resin and the composition of the organosiloxane (particularly the molecular chain length), it is possible to control the compatibility of the epoxy resin or phenolic resin with silicone and to control the silicone particle size quite accurately. This results in a system in which product variations are kept to a minimum and material design is extremely easy.

In the present invention, the combined use of a high modification rate silicone-modified epoxy resin and a high modification rate silicone-modified phenol resin results in lower stress and toughness compared to when they are used alone, resulting in extremely excellent thermal shock resistance and soldering heat resistance. This is because the moldability is improved due to the improved compatibility between the epoxy resin component and the phenol resin component. If a silicone-modified epoxy resin with a silicone modification rate of 95% or less or a silicone-modified phenol resin with a silicone modification rate of 95% or less is used in combination, the bleeding of unreacted silicone compounds cannot be suppressed.
Molding processability deteriorates, and furthermore, as the silicone domain particle size increases, strength decreases, thermal shock resistance and soldering heat resistance decrease, and sufficient resin properties cannot be obtained.

The combined ratio of both is 30 to 80 parts by weight of silicone-modified phenol resin to 100 parts by weight of silicone-modified epoxy resin.
! If the amount is less than 30 parts by weight, the compatibility between the silicone-modified epoxy resin component and the silicone-modified phenol resin component is not sufficiently improved, resulting in poor moldability.
Furthermore, since the equivalent ratio of epoxy groups to phenolic OH groups is large and deviates from 1, curing is not performed sufficiently and thermal shock resistance and soldering heat resistance are reduced.

If it exceeds 80%, the same problem will occur and the resin composition will not be able to exhibit sufficient properties.

In addition to the silicone-modified epoxy resin, it is also possible to add ordinary unmodified epoxy resin as an epoxy resin component within a range that does not reduce the effect of silicone modification.
The proportion thereof is 0 to 150 parts by weight per 100 parts by weight of the silicone-modified epoxy resin. Similarly, for the silicone-modified phenolic resin used as a curing agent, it is possible to use a normal unmodified phenol resin in combination, and the proportion thereof is in the range of 0 to 150 parts by weight per 100 parts by weight of the silicone-modified phenolic resin. You can.

Furthermore, it is also possible to use an unmodified epoxy resin and a phenol resin at the same time, and in this case, it is necessary to determine the ratio while taking into account the amount of silicone in the entire resin and taking into account curability and the like.

The ratio of these combined use is silicone modified epoxy resin 100%
Normal unmodified epoxy resin 0-150 parts by weight
Parts by weight, 0-150 parts by weight of ordinary unmodified 7-enol resin for 100 parts by weight of silicone-modified phenolic resin, 30-80 parts by weight of total phenolic resin for 100 parts by weight of total epoxy resin, and The amount including the epoxy resin component and the total phenolic resin component is 40% of the total resin amount.
It is necessary to account for ~100% by weight.

In the case of both epoxy resins and phenolic resins, if the proportion of the normal unmodified resin is out of the above-mentioned range, the compatibility between the silicone modified resin and the unmodified resin decreases, resulting in a decrease in moldability. Furthermore, since the amount of silicone component is reduced, low stress properties and thermal shock resistance are reduced.

In order to obtain an epoxy resin composition for semiconductor encapsulation using the composition of the present invention, in addition to the above-mentioned silicone modified resin and unmodified resin, inorganic fillers such as crystalline silica, fused silica, mica, alumina, and calcium carbonate are used. , talc, glass fiber, etc., and these can be used alone or in a mixture of two or more, and among these, crystalline silica or fused silica is particularly preferably used. Other BDM as needed
Curing accelerators such as tertiary amines such as A, imidazoles, organic phosphorus compounds such as 1,8-diazabicyclo(5,4,0)undecene-7 and tri-7enylphosphine, natural waxes, and synthetic waxes. mold release agents such as hexabromobenzene, decabromo biphenyl ether, antimony trioxide, colorants such as carbon black and red iron, silane coupling agents, other synthetic rubbers, silicone compounds, thermoplastic resins, etc. as appropriate. After addition and blending, these raw materials are thoroughly mixed using a mixer or the like, and then heated and melt-mixed using a kneader or roll, followed by cooling, solidification, and pulverization treatment to obtain an epoxy resin composition.

(Example) Silicone-modified epoxy resin (A) Shown by structural formula (I) obtained by reacting a reaction product of 0-cresol novolak epoxy resin and ◇-allylphenol with a silicone compound having H-3i groups at both ends. Silicone modified epoxy resin (silicone modification rate R: 9
7. Epoxy equivalent: 250°, softening point: 75°C) In/m+nri-j: 1) 47. i/m) f14
i, Ql Co OJ k#190 Silicone-modified epoxy resin (B) Silicone-modified epoxy resin represented by the following structural formula (n) (Silicone modification rate R: 99. Epoxy equivalent: 252.
Softening point 78℃) m/III+n+1-QOj) i/m+n+im
o, 01 k=95 silicone modified epoxy resin (
C) Silicone-modified epoxy resin represented by the following structural formula (III) (silicone modification rate R: 95. Epoxy equivalent: 26
0. Softening point 78℃) IR/a4n+Iwl102, shi+n4n+i-
0,01, ni-95 silicone-modified epoxy resin CD) Silicone-modified epoxy resin represented by structural formula (I) (
Silicone modification rate R near 9. Epoxy equivalent: 250, softening point: 75°0) Silicone-modified epoxy resin (E) Silicone-modified epoxy resin represented by structural formula (III) (Silicone modification rate R: 52. Epoxy equivalent: 260,
Softening point: 78°C) The above silicone-modified epoxy resins were synthesized based on Tables 1 and 2.

(Left below) 25 parts by weight of organopolysiloxane represented by the following structural formula (Vl) having 6 epoxy groups in one molecule of silicone-modified phenolic resin (F, G, H, I) and the weight of 7-functional novolak. 100 parts by weight were reacted at a reaction temperature of 140° C. by changing the catalyst type and reaction time to obtain 4ai silicone-modified phenolic resins having different silicone modification rates as shown in Table 3.

Next, examples will be described together with comparative examples.

Examples 1-6. Comparative Examples 1 to 8 Next, silicone modified resins A and B obtained as described above
, C, D, E, F, G, H, I and other raw materials according to Table 2, mixed thoroughly at room temperature, and then heated to 95-100°C.
The mixture was kneaded, cooled, and pulverized to obtain an epoxy resin composition for semiconductor encapsulation.

The moldability of these materials (mold stains, resin flakes) was determined using a transfer molding machine (molding conditions: mold temperature: 175°C, curing time: 1 minute), and the crack resistance of the packages post-cured for 8 hours was evaluated. evaluated.

The resin composition using the high modification rate silicone-modified phenolic resin and the novolak type phenolic resin of the present invention exhibited very excellent moldability and thermal shock resistance. The results are shown in Table 4.

(Margins below) Judgment based on the number of molded shots until the appearance of wood type clouding.

+2 Measure the length of the resin pad at the vent part of the molded product obtained.

Use the molded product from the 310th shot of the tree, 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.

*4 20 molded products (post-cured at 175°C, 3Hrs) were subjected to a temperature cycle test (-65°C1-+150'C) for 1,000 cycles and judged based on the number of cracks that occurred. The table shows the number of cracks in 20 molded products.

*5 100 molded products (post-cured at 175°C + 8 hours) were subjected to a moisture resistance test for 1,000 hours under high-pressure steam at 120°C to determine the number of defective products. The table shows the number of defective items out of 100.

*6 After processing for 144 hours at 85°C and 85RH for 16 molded products (post-curing 175°C, 8Hrs), 28
The molded product was immersed in a solder bath at 0°C 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 comprising a high modification rate silicone-modified epoxy resin and a high modification rate silicone-modified phenol resin of the present invention has excellent molding processability such as mold stains and resin flakes. It is an epoxy resin composition for semiconductor encapsulation that has excellent marking properties, moisture resistance, thermal shock resistance, and soldering heat resistance, and is used for encapsulation, coating, insulation, etc. of electronic and electrical components. In this case, products with extremely high reliability can be obtained, especially in highly integrated large-chip ICs mounted on surface mount packages.

Claims (4)

[Claims] (1) (a) Silicone modified epoxy resin whose silicone modification rate R calculated from the following formula [I] is 95≦R≦100 (b) silicone modification rate R calculated from the following formula [I] is 95≦R≦ Silicone modified phenolic resin R=(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: Ratio of the silicone modified resin in the sample solution Weight/weight of standard substance in sample solution C: Silicone component content in silicone-modified resin (weight of silicone compound added during silicone-modified resin production reaction) K: Weight of silicone compound corresponding to unit area of silicone compound peak/ An epoxy resin composition whose essential component is the weight of cholesterol acetate per unit area of a standard substance. (2) The epoxy resin composition according to claim 1, wherein the epoxy resin composition contains an unmodified epoxy resin. (3) The epoxy resin composition according to claim 1, wherein the epoxy resin composition contains an unmodified phenolic resin. (4) The epoxy resin composition according to claim 2, wherein the epoxy resin composition contains an unmodified phenolic resin.