JPH07258364A - Phenolic curative and semiconductor-sealing resin composition containing the same - Google Patents

Abstract

PURPOSE:To obtain a phenolic curative for a semiconductor-sealing resin by reacting a phenol, t-butylbenzaldehyde or phenoxybenzaldehyde, and a specific xylylene compd. CONSTITUTION:A phenolic curative of the formula II (wherein R1 is t-butyl or phenoxy; and m and n are each 1-10) is obtd. by mixing a phenol (A), t- butylbenzaldehyde or phenoxybenzaldehyde (B), and a xylylene compd. (C) of the formula I (wherein R is H, 1-4C alkyl, or 2-4C acyl) (e.g. xylylene glycol) in molar ratios of (B+C)/A and C/B of 0.1-0.8 and 0.1-10, respectively, adding 0.003-5wt.% acid catalyst (e.g. phosphoric acid) to the resultant mixture, and thermally reacting it. A semiconductor-sealing resin compsn. is prepd. by compounding an epoxy resin, the phenolic curative in an equivalent ratio of the hydroxyl group to the epoxy group of about 0.5-1.5, and an inorg. filler (e.g. crystalline silica).

Description

Detailed Description of the Invention

[0001]

The present invention relates to solder heat resistance, moisture resistance,
The present invention relates to a resin composition for semiconductor encapsulation having excellent heat resistance (high Tg) and moldability.

[0002]

2. Description of the Related Art As a sealing method for electronic circuit parts such as semiconductor devices, hermetic sealing using metal or ceramics and resin sealing using phenol resin, silicone resin, epoxy resin, etc. have been proposed. Among them, the resin encapsulation with an epoxy resin is the main focus from the viewpoint of balance of economy, productivity and physical properties. In particular, a large amount of epoxy resin molding materials using phenol novolac as a curing agent in an epoxy resin having cresol novolac as a skeleton are used.

However, in recent years, along with the downsizing of electronic parts, the upsizing of semiconductor elements, the increase in the degree of integration, etc., conventional epoxy resin molding materials have been sufficiently compatible with respect to moisture resistance, heat resistance and reliability. It's getting harder.

Particularly in recent years, packaging and mounting on a printed circuit board have been promoted with higher density and automation. Instead of the conventional mounting method of inserting lead pins into the holes of the board,
The "surface mounting method" in which components are soldered to the surface of the board is becoming mainstream. Along with this, the package is a thin TSOP (spin-in type) suitable for high-density mounting and surface mounting from the conventional dual in-line package (DIP).
Small outline packages) and QFP (quad flat packages) are being migrated.
With such changes in mounting method and thinning of semiconductor packages, securing reliability of elements has become an important issue.

That is, in the conventional pin insertion mounting method, the soldering process only partially heats the lead portion, but in the surface mounting method, the entire package is 210 to 280.
Since it is heated to ℃, along with the thinning of the package, the conventional sealing resin may crack the resin part during the soldering process or peel off the element and resin,
The problem has arisen that the reliability is significantly reduced.

The occurrence of cracks in the soldering process is
This is because the moisture absorbed inside the package suddenly becomes steam and expands due to the heating during soldering.
As countermeasures against this, studies have been added from various aspects such as epoxy resin main agent, curing agent, curing accelerator, and filler.

Among them, a method of reducing the moisture absorption and the stress by increasing the amount of the filler is also one of the means for improving the solder heat resistance, but for that purpose, in view of the balance with the fluidity at the time of molding, It is necessary to reduce the viscosity. However, lowering the viscosity of the resin not only leads to a lower glass transition temperature, but has also been pointed out as a problem of cold flow due to a lower softening point.

On the other hand, the role of the curing agent is extremely important. There are two main directions for improving curing agents. One is a method of increasing the glass transition point by using a polyfunctional curing agent, and the other is a curing agent having a high phenolic hydroxyl group equivalent. Is a method of imparting low hygroscopicity and low stress.

As an example of the former, a method using tris (hydroxyphenyl) methane as a curing agent (JP-A-62-1)
No. 84012, JP-A-1-268713), and as an example of the latter, a method using a phenol aralkyl resin as a curing agent (JP-A-59-101018, JP-A-59-6).
7660, JP-A-64-60623) and a method using a dicyclopentadiene / phenol polymer (JP-A-4-359013). Also, a method of combining the two (Japanese Patent Laid-Open No. 1-292029) has been reported. However, the encapsulating resins improved by these methods are still not sufficient although they have some effect on the prevention of cracks in the soldering process, and each has its drawbacks. For example, in the method using tris (hydroxyphenyl) methane as a curing agent, it has been pointed out that the water absorption rate increases although the crosslink density of the resin increases, and that the resin itself becomes brittle, and is particularly effective for thin packages such as TSOP. Is hardly recognized. Further, in the method using a phenol aralkyl resin as a curing agent, the solder heat resistance is improved, but it is still insufficient, and further, moldability such as curability and releasability is lowered, and the glass transition temperature is also lowered. ing.

Further, as a curing agent, dicyclopentadiene.
When a phenolic polymer is used, it has excellent moisture resistance and a relatively high glass transition temperature, but it has a problem that it is inferior in curability and mold releasability during molding. Since it has a high softening point, it has a drawback in workability such as compounding and kneading.

In order to solve the above problems, the present inventor uses a phenolic curing agent having a specific molecular structure, which is obtained by reacting an aromatic aldehyde with a xylylene compound as a crosslinking agent for phenols. (Japanese Patent Application No. 5-48737). The encapsulant obtained by the present invention has solder heat resistance, moldability, low viscosity,
It showed a well-balanced performance in terms of glass transition temperature, cold flow, etc., and made it possible to greatly improve the various problems mentioned above. However, it is still insufficient to meet increasingly severe requirements for solder crack resistance such as dry pack-less TSOP.

[0012]

In view of such a situation, the present inventors have solved the above-mentioned problems and obtained a phenol-based resin for obtaining a semiconductor encapsulating resin that can be used in a highly integrated IC thin package. As a result of research to find a curing agent, the inventors have found that the above problems can be solved by using a phenolic curing agent having a specific molecular structure, which is a further improvement of the above proposal, and have reached the present invention.

Therefore, an object of the present invention is to provide a semiconductor encapsulating resin having low hygroscopicity, excellent solder heat resistance, moldability (fluidity / curability / releasability), and heat resistance (high Tg). It is intended to provide a phenolic curing agent for production and a resin composition for semiconductor encapsulation containing the phenolic curing agent as an essential component.

[0014]

The present invention relates to phenols and tertiary butylbenzaldehyde or phenoxybenzaldehyde and the general formula (1).

[Chemical 2] (Wherein R represents hydrogen, an alkyl group having 1 to 4 carbon atoms, or an acyl group having 2 to 4 carbon atoms) and a phenolic curing agent for a resin for semiconductor encapsulation obtained by reacting with a xylylene compound It is an agent.

The present invention also includes (a) an epoxy resin, (b)
It includes a resin composition for semiconductor encapsulation comprising the phenolic curing agent according to the above invention and (c) an inorganic filler as essential components.

The present invention will be described in detail below. The phenolic curing agent which is the first invention of the present invention comprises reacting phenols with tertiary butylbenzaldehyde or phenoxybenzaldehyde and a xylylene compound represented by the general formula (1) in the presence of an acid catalyst. , Can be easily manufactured.

As the phenols used as the raw material of the present curing agent, various monocyclic, polynuclear or condensed polycyclic aromatic compounds having one or two or more hydroxyl groups bonded to an aromatic ring can be used. Can be used. As a specific example,
Phenol; Substituted phenols such as cresol, xylenol, ethylphenol, butylphenol, halogenated phenol; Dihydric phenols such as resorcin, bisphenol A, bisphenol S, bisphenol F; Condensation of α-naphthol, β-naphthol, naphthalenediol, etc. Examples thereof include polycyclic phenols. Of these phenols, phenol, cresol, α- or β-naphthol is preferably used.

The aromatic aldehyde used as a raw material of the present curing agent is tert-butylbenzaldehyde or phenoxybenzaldehyde (hereinafter, these may be referred to as substituted benzaldehyde). The position of the substituent of the substituted benzaldehyde may be any of ortho, meta and para, but a para or meta substituent is particularly preferable.

The xylylene compound used as a raw material of the present curing agent is represented by the above formula (1). Examples of such xylylene compound include xylylene glycol, xylylene glycol dimethyl ether, xylylene glycol diethyl ether, and xylylene. Examples include ren glycol diacetoxy ester, xylylene glycol dipropoxy ester, and the like, but especially xylylene glycol,
Xylylene glycol dimethyl ether and the like are preferable. The substitution position of —CH ₂ OR in the formula (1) may be any of ortho, meta and para, but the para position is generally preferable.

Each of the three raw material components of the curing agent may be used singly or as a mixture of two or more kinds.

The acid catalyst used in the production of the present curing agent includes inorganic acids such as phosphoric acid, sulfuric acid and hydrochloric acid, and organic acids such as oxalic acid, benzenesulfonic acid, toluenesulfonic acid, methanesulfonic acid and fluoromethanesulfonic acid. Alternatively, Friedel-Crafts type catalysts such as zinc chloride, stannic chloride, ferric chloride and diethyl sulfate can be used alone or in combination.

With respect to the use ratio of each raw material, the total amount of the substituted benzaldehyde and the xylylene compound with respect to the phenol is preferably 0.1 to 0.8 in terms of molar ratio. If this molar ratio is less than 0.1, unreacted phenol increases and the yield decreases, which is not preferable. On the other hand, if it exceeds 0.8, the molecular weight of the produced resin increases, the softening temperature rises, and the fluidity at the time of molding tends to be lowered, which is not preferable. A more preferable ratio is 0.2 to 0.7.

On the other hand, the molar ratio of the xylylene compound to the substituted benzaldehyde is appropriately in the range of 0.1-10. If it is less than 0.1, the cured product obtained by adding and curing the epoxy resin tends to be slightly stiff and brittle. Again 10
If it is larger than the above range, the solder crack resistance and the moldability are deteriorated, and the glass transition point is lowered, so that the object of the present invention cannot be satisfied. A more preferable ratio is 0.2 to 5.

The amount of the acid catalyst used is not particularly limited, but depending on the type of the catalyst and the raw materials, it is 0.
It is preferable to add an appropriate amount within the range of 003 to 5% by weight.

Phenols and substituted benzaldehydes,
The reaction with the xylylene compound is usually 100 to 180.
C., preferably in the temperature range of 110 to 160.degree. The reaction time is generally 1 to 10 hours.

When reacting a phenol with a substituted benzaldehyde and a xylylene compound in the presence of an acid catalyst, the substituted benzaldehyde and the xylylene compound may be added simultaneously to proceed the reaction, or one of them may be added first to the reaction. Alternatively, the other can be added to continue the reaction.

This reaction proceeds while producing alcohol or carboxylic acid depending on the type of xylylene compound used, in addition to water produced by condensation. After the completion of the condensation reaction, the unreacted phenols remaining in the system are distilled off under a vacuum or by an appropriate method such as steam distillation to obtain the phenolic curing agent of the present invention. If necessary, the acid catalyst can be removed.

The phenolic curing agent thus obtained is
Both components of the substituted benzaldehyde and the xylylene compound act as a linking agent for phenols, and both components are randomly linked via the phenols. An example of the typical structure is shown in Formula (2). However, the structural units in [] are randomly distributed in the copolymer.

[0029]

[Chemical 3]

In the above formula, R ₁ is a tertiary butyl group or a phenoxy group. m and n are usually integers of 1 to 10.

The values of m and n in the above formula are phenols,
By changing the compounding ratio of the three raw material components of the substituted benzaldehyde and the xylylene compound, the desired physical properties can be arbitrarily adjusted.

In the present invention, this curing agent is used alone or in combination with known curing agents such as phenol novolac resin, phenol aralkyl resin, and tris (hydroxyphenyl) methane according to the purpose within the range of not impairing the effects of the present invention. Can be used.

A second invention of the present invention is that the phenolic curing agent obtained by the above method is a curing agent (component (b)),
A resin composition for semiconductor encapsulation, comprising (a) an epoxy resin, (b) a phenol-based curing agent, and (c) an inorganic filler as essential components.

The epoxy resin (a) used in the present invention is not particularly limited, and a known epoxy resin containing two or more glycidyl groups in one molecule is used.

Specific examples include moisture resistance, low stress,
Formula (3) has excellent heat resistance.

[Chemical 4] (However, R _{1 to} R ₄ are alkyl groups having 1 to ₄ carbon atoms, and R _{1 to} R ₄ may be the same or different),
Formula (4)

[0036]

[Chemical 5]

(However, two of R _{1 to} R ₈ are 2,3-epoxypropoxy groups, and the other groups are independently a hydrogen atom, a C _{1 to} C ₄ lower alkyl group or a halogen. An epoxy resin represented by (which is an atom) is a particularly preferable example. Further, various novolac type epoxy resins such as cresol novolac type epoxy resin and phenol novolac type epoxy resin are also preferable specific examples. In addition, a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a fluorenone type epoxy resin, and various polyfunctional epoxy resins can be used.

From the viewpoint of heat resistance, moisture resistance and mechanical properties, the compounding ratio of (b) phenolic curing agent to (a) epoxy resin is such that the equivalent ratio of hydroxyl group / epoxy group is 0.5-.
It is preferably in the range of 1.5, particularly 0.8 to 1.2.

Even when the combined epoxy resin and / or combined phenol resin curing agent is used, the ratio of the total hydroxyl equivalent of the entire phenol resin curing agent / the total epoxy equivalent of the entire epoxy resin is 0.5 to 1.5, Especially 0.8 ~
The range may be 1.2.

As the inorganic filler (C) used in the present invention, amorphous silica, crystalline silica, alumina, glass,
Calcium silicate, gypsum, calcium carbonate, magnesite, clay, kaolin, talc, mica, magnesia,
Among them, barium sulfate and the like, among them, crystalline silica and amorphous silica are most preferable in terms of high purity and low thermal expansion coefficient.

The addition amount of these inorganic fillers is 60 to 9 in the whole resin composition for semiconductor encapsulation of the present invention.
5% by weight is preferred. When the content of the inorganic filler is less than 60% by weight, the solder heat resistance is insufficient, and when it exceeds 95% by weight, the fluidity during molding becomes insufficient. Moldability (melt viscosity,
From the viewpoint of solder heat resistance such as low stress and low hygroscopicity, it is preferable that the amount of the filler is large as long as the fluidity is not impaired. For this purpose, it is preferable to use a spherical filler having a wide particle size distribution in order to achieve the closest packing.

The resin composition for semiconductor encapsulation of the present invention may contain various additives, if necessary, in addition to the above-mentioned epoxy resin, phenolic curing agent, and inorganic filler. Examples of the additive include a curing accelerator, a flame retardant, a flame retardant aid, a release agent, a coloring agent, a stress reducing agent, an ion trapping agent, and an anticorrosive agent, and any conventionally known one can be used.

The curing accelerator is not particularly limited as long as it accelerates the curing reaction between the epoxy resin and the phenolic curing agent. For example, 2-methylimidazole, 2,4-
Dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4
-Tert-amines such as methylimidazole, triethylamine, triethylenediamine, benzylmethylamine, 2,4,6-tris (dimethylaminomethyl) phenol, 1,8-diazabicyclo (5,4,0) undecene-7, etc. Amine, triphenylphosphine,
Organic phosphine compounds such as trimethylphosphine, triethylphosphine, tributylphosphine, tri (p-methylphenyl) phosphine, tri (nonylphenyl) phosphine, tetraphenylphosphonium tetraphenylborate, triphenylphosphine tetraphenylborate, 2-ethyl-4- Examples thereof include tetraphenylboron salts such as methylimidazole tetraphenylborate. Among them, organic phosphine compounds are preferable, and triphenylphosphine is particularly preferable, from the viewpoint of moisture resistance.

These curing accelerators may be used in an amount of 1 depending on the purpose.
, Or two or more kinds may be used in combination, and the addition amount thereof is
(A) 0.1 to 5 relative to 100 parts by weight of epoxy resin
The range of parts by weight is preferable in terms of curing characteristics and physical properties.

Examples of flame retardants include halogenated epoxy resins, halogen compounds and phosphorus compounds, and examples of flame retardant aids include antimony trioxide. Examples of the release agent include carnauba wax, paraffin wax, stearic acid, montanic acid, and carboxyl group-containing polyolefin, and examples of the colorant include carbon black. Examples of the stress reducing agent include silicone rubber,
Examples thereof include modified nitrile rubber, modified butadiene rubber, modified silicone oil and the like. Of course, these various additives are not limited to those exemplified here. The amount of these additives added may be the same as in the conventional semiconductor encapsulating resin composition.

As a general method for preparing the resin composition for semiconductor encapsulation of the present invention as a molding material, the raw material components selected in a predetermined composition ratio are thoroughly mixed with, for example, a mixer, and then heated rolls or It can be easily obtained by a method such as kneading with a kneader or the like, cooling and solidifying, and then pulverizing to an appropriate size.

The molding material thus obtained can be used for semiconductor encapsulation by a molding method such as a low-pressure transfer molding method.

The present invention will be specifically described below with reference to examples.

【Example】

Example 1 (Production of Phenolic Curing Agent) A four-necked flask equipped with a stirrer, a thermometer, a condenser, and a nitrogen gas inlet tube was charged with 588 parts by weight of phenol.
162 parts by weight of p-tert-butylbenzaldehyde,
224 parts by weight of p-xylylene glycol dimethyl ether and 0.2 parts by weight of trifluoromethane sulfonic acid were added, and the mixture was heated to 130 to 140 ° C., dehydration and demethanol were carried out, and reaction was carried out until generation of condensate was not observed. It was Thereafter, the unreacted phenol and the catalyst in the system were removed by vacuum distillation to obtain the target product. The obtained condensation reaction product had a softening point of 88 ° C. (ring and ball method) and a hydroxyl equivalent of 179 g / eq.

Example 2 (Production of Phenolic Curing Agent) In a four-necked flask equipped with a stirrer, a thermometer, a condenser, and a nitrogen gas introduction tube, 686 parts by weight of α-naphthol and p-tert-butyl were added. Benzaldehyde 124 parts by weight, p-xylylene glycol dimethyl ether 190
By weight, 2 parts by weight of p-toluenesulfonic acid (monohydrate) was added, and the mixture was heated to 130 to 140 ° C., and dehydration and demethanol were carried out, and the reaction was carried out until generation of a condensate was not observed. Then, the reaction product was dissolved in methylene chloride, washed with a separating funnel, and then the solvent and unreacted naphthol were removed from the organic layer by vacuum distillation to obtain the target product. The obtained condensation reaction product has a softening point (ring and ball method) of 9
The hydroxyl equivalent was 202 g / eq at 3 degreeC.

Example 3 (Production of Phenolic Curing Agent) A four-necked flask equipped with a stirrer, a thermometer, a condenser, and a nitrogen gas inlet tube was charged with 568 parts by weight of phenol.
191 parts by weight of m-phenoxybenzaldehyde, 241 parts by weight of p-xylylene glycol dimethyl ether, and 0.2 parts by weight of trifluoromethanesulfonic acid were added to give 13 parts.
While heating to 0 to 140 ° C., dehydration and demethanol were carried out, and the reaction was carried out until generation of a condensate was not observed. Then, the unreacted phenol and the catalyst were removed by vacuum distillation to obtain the target product. The condensation reaction product thus obtained has a softening point (ring and ball method) of 90 ° C. and a hydroxyl group equivalent of 19
It was 4 g / eq.

Comparative Example 1 (Production of Phenolic Curing Agent) A four-necked flask equipped with a stirrer, a thermometer, a condenser, and a nitrogen gas introducing tube was charged with 634 parts by weight of phenol.
Addition of 143 parts by weight of benzaldehyde, 224 parts by weight of p-xylylene glycol dimethyl ether, and 1.0 part by weight of p-toluenesulfonic acid, heating at 130 to 140 ° C., dehydration and demethanol formation were observed while condensate was generated. The reaction was carried out until it was stopped. Then, the unreacted phenol in the system was removed by vacuum distillation to obtain the target product. The obtained condensation reaction product has a softening point of 84 ° C.
(Ring and ball method) has a phenolic hydroxyl group equivalent of 156 g / e.
It was q.

The phenolic curing agents (B1 to B4) obtained in Examples 1 to 3 and Comparative Example 1 and the conventional phenolic curing agents (B5, B6) were used as raw materials for the resin composition for semiconductor encapsulation. The epoxy resins (A1 to A3) used are shown in Table 1.

[Examples 4 to 8 and Comparative Examples 2 to 5] (Production of resin composition for semiconductor encapsulation) Epoxy resins shown in Table 1, phenolic curing agents and other additives shown in Tables 2 and 3. The components are blended in the blending ratios shown in Tables 2 and 3, sufficiently pre-mixed, kneaded with a mixing roll, cooled, and then pulverized to form the desired semiconductor encapsulating resin composition. A molding material was obtained.

In the above Examples and Comparative Examples, in order to compare the results under the same conditions, the compounding ratio of the phenolic curing agent and the epoxy resin is such that the equivalent ratio of hydroxyl group / epoxy group is 1/1, and The total amount of the phenolic curing agent and the epoxy resin contained in the material was set to a constant value of 17% by weight.

The physical properties of these sealing materials are measured by
The procedure was as follows. (1) Spiral flow (flowability) 70 kg of molding material with a transfer mold at 175 ° C
The flow distance when a pressure of f / cm ² was applied was measured.

(2) Molding and Curing Property The molding material was transfer-molded at 175 ° C. for 120 seconds and the hardness at 10 seconds after the mold release was measured to evaluate the molding and curability.

(3) Glass transition temperature The molding material was transferred to a transfer molding machine at 175 ° C.
After molding under a condition of 120 seconds, a test piece of an appropriate size was cut out from a molded product which was cured at 150 ° C. for 2 hours and then at 180 ° C. for 6 hours, and the glass transition temperature was measured by the TMA method.

(4) Moisture Absorption Rate A test semiconductor element was molded at 175 ° C. by using a molding material.
By performing low-pressure transfer molding under the condition of 120 seconds, TSOP (package size: 16 × 6.2 × 1.0
mm) was created. After molding and sealing, post-curing was performed at 150 ° C. for 2 hours and then at 180 ° C. for 6 hours. The moisture absorption rate was measured from the weight change after the package was made to absorb moisture in an atmosphere of 85 ° C. and a relative humidity of 85% RH for 120 hours.

(5) Solder heat resistance 20 test packages immediately after the moisture absorption rate was measured were
The crack generation rate was determined from the number of cracks generated when immersed in a solder bath at 60 ° C. for 20 seconds, and this was taken as the solder heat resistance.

Table 4 shows the evaluation results of the physical properties of the sealing material samples obtained in the examples and the comparative examples.

[0061]

[Table 1]

[0062]

[Table 2]

[0063]

[Table 3]

[0064]

[Table 4]

As is clear from the results shown in Table 4, in Examples 4 to 7 using the phenolic curing agents B1 to B3 of the present invention, the crack occurrence rate after immersion in the solder bath was low, and the mold curability was also high. The heat resistance (glass transition temperature) was also good. On the other hand, a curing agent B4 (phenol / benzaldehyde / p- which is an unsubstituted benzaldehyde as a linking agent)
Comparative Example 2 using a condensate of xylylene dimethoxide)
In Nos. 5 and 5, the rate of occurrence of solder cracks is higher than that in the examples. Further, Comparative Example 3 using a phenol aralkyl resin as the curing agent was inferior not only in the solder cracking property but also in the curing property and the heat resistance (glass transition temperature). Further, in Comparative Example 4 in which phenol novolac was used as the curing agent, the moisture absorption rate was high, and the crack generation rate after immersion in the solder bath was significantly high.

[0066]

As described above, the resin composition for semiconductor encapsulation of the present invention is extremely excellent in solder crack resistance, moldability (curability / releasability / fluidity), heat resistance (high glass transition). Since temperature) and moisture resistance are also good, a semiconductor device having excellent solder heat resistance and reliability as a semiconductor sealing material can be obtained.

Claims (2)

[Claims] 1. Phenols and tertiary butylbenzaldehyde or phenoxybenzaldehyde and a compound represented by the general formula (1): (Wherein R represents hydrogen, an alkyl group having 1 to 4 carbon atoms, or an acyl group having 2 to 4 carbon atoms) and a phenolic curing agent for a resin for semiconductor encapsulation obtained by reacting with a xylylene compound Agent. 2. A semiconductor encapsulating resin composition containing (a) an epoxy resin, (b) the phenolic curing agent according to claim 1 and (c) an inorganic filler as essential components.