JP2948056B2 - Resin composition for semiconductor encapsulation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition for semiconductor encapsulation having a low hygroscopicity, a high glass transition temperature, and excellent solder heat resistance.

[0002]

2. Description of the Related Art Conventionally, as a method of sealing an electronic circuit component such as a semiconductor device, a hermetic seal made of metal or ceramic and a resin seal made of phenol resin, silicone resin, epoxy resin or the like have been proposed. Among them, resin sealing with an epoxy resin is mainly used in view of balance between economy, productivity and physical properties. In particular, epoxy resin molding materials using phenol novolak as a curing agent for an epoxy resin having cresol novolak as a skeleton have been used in large quantities.

In recent years, however, with the miniaturization of electronic parts, the enlargement of semiconductor elements, and the increase in integration, conventional epoxy resin molding materials have not sufficiently responded to moisture resistance, heat resistance and reliability. It's getting harder.

In recent years, package mounting on a printed circuit board has recently been increased in density and automation, and instead of the conventional mounting method of inserting lead pins into holes in the board,
The “surface mounting method” of soldering components to the surface of a substrate is becoming mainstream. Accordingly, packages have been shifting from conventional dual in-line packages (DIP) to thin types such as flat packages (FP) and small-out packages (SOP) suitable for surface mounting. With such a change in the mounting method and the thinning of the semiconductor package, securing the reliability of the device has become an important issue. That is, in the conventional pin insertion mounting method, the lead portion is only partially heated in the soldering process.
Since it is heated to 0 to 280 ° C, the reliability of the conventional encapsulating resin is reduced due to cracks in the resin part and peeling off of the element and resin in the soldering process, in combination with the thinning of the package. The problem of significant decline has arisen.

[0005] The occurrence of cracks in the soldering process
This is due to the fact that the moisture absorbed inside the package is vaporized and expanded at a stretch by heating at the time of soldering, and as a countermeasure for this, various improvements in sealing resins have been studied. These improvements are based on epoxy resin base, hardener,
Although it has been studied from various aspects such as curing accelerators and fillers,
Among these, there are two main directions for improving the curing agent, one of which is to increase the glass transition point by using a polyfunctional curing agent, and the other is to increase the phenolic hydroxyl equivalent. This method uses a high curing agent to impart low moisture absorption and low stress.

An example of the former is 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-59-1015018, JP-A-59-6106).
No. 7660, JP-A-64-60623) are known. Also, a method of combining both (Japanese Patent Laid-Open No. 1-2920)
No. 29) has also been reported. However, although the sealing resin improved by these methods has been effective to some extent in preventing cracks in the soldering process, it is still insufficient, and each has its own drawbacks. For example, in the method using tris (hydroxyphenyl) methane as a curing agent, although the crosslink density of the resin is increased, it has been pointed out that the water absorption rate is increased and the resin itself is brittle. In particular, in the case of a thin package, the effect of preventing cracks is small. Further, the method using a phenol aralkyl resin as a curing agent has a disadvantage that the glass transition point of the resin is significantly reduced.

[0007]

SUMMARY OF THE INVENTION In view of the above situation, the present invention provides a resin composition for semiconductor encapsulation which has both low water absorption and a high glass transition point, and is excellent in solder heat resistance and reliability. Aim.

[0008]

In order to solve the above-mentioned problems, the present inventors have conducted various studies on a curing agent for an epoxy resin, and as a result, have found that a phenol comprising a mixture of a phenolic resin having a specific molecular structure is obtained. The inventors have found that the above-mentioned problems can be solved by using a system curing agent, and have reached the present invention.

That is, the present invention provides (a) an epoxy resin,
(B) a phenolic curing agent, (c) a curing accelerator, (d)
A resin composition containing an inorganic filler as an essential component, wherein (b) a phenolic curing agent comprises an addition condensate (1) of a phenol, benzaldehyde or naphthaldehyde, and a phenol aralkyl resin ( 2) and
(1) / (2) compounding ratio (weight ratio) 25/75 to 85/15
A resin mixture for semiconductor encapsulation, characterized by being a mixture mixed by: Hereinafter, the present invention will be described in detail.

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. As a specific example, a material having excellent resistance to moisture, low stress and heat can be obtained by the formula (1)

Embedded image (However, R ^{1 to} R ⁴ are an alkyl group having 1 to ⁴ carbon atoms). Various novolak epoxy resins such as cresol novolak epoxy resin and phenol novolak epoxy resin are also preferable specific examples. In addition, bisphenol type epoxy resin having a fluorene skeleton,
Bisphenol A type epoxy resin, bisphenol F type epoxy resin and the like can also be used.

In the present invention, phenols and benzaldehyde or naphtha are used as (b) a phenolic curing agent.
It is characterized in that both the addition condensation product of aldehyde (1) and the phenol aralkyl resin (2) are used as essential components.

Phenols and benzaldehyde or
Addition condensate of naphthaldehyde are phenols and the aromatic aldehyde, is reacted in the presence of an acid catalyst,
It can be easily manufactured.

Examples of phenols used as a raw material of the above-mentioned addition condensate include phenol, cresol, xylenol, ethylphenol, butylphenol, halogenated phenol, resorcinol, bisphenol A, bisphenol S, bisphenol F, and the like. Preferably, phenol or cresol is used.
Phenols having a condensed polycyclic aromatic skeleton such as α-naphthol, β-naphthol, and naphthalene diol are also preferred specific examples.

Aldehydes to be added and condensed with phenols
From benzaldehyde and naphthaldehyde
The selected aromatic aldehyde is used.

[0015] As the acid catalyst used in the reaction of the phenol with the aromatic aldehyde, phosphoric acid, sulfuric acid, hydrochloric acid,
And inorganic acids such as oxalic acid, benzenesulfonic acid, toluenesulfonic acid, and methanesulfonic acid.

[0016] The reaction of a phenol and the aromatic aldehydes, charged at a rate of 0.9 to 0.1 moles of an aromatic aldehyde to phenol 1 mole, after adding an appropriate amount of an acid catalyst, usually 100 This is carried out at a temperature of 180 ° C. for about 1 to 10 hours. After the completion of the condensation reaction, the unreacted phenols remaining in the system are distilled off under vacuum or by a suitable method such as steam distillation to obtain the desired product.

The phenol aralkyl resin, which is another component of the phenolic curing agent (b) of the present invention, has a repeating unit represented by the following formula (2) as a typical example, and includes aralkyl ether, aralkyl ester,
A resin obtained by reacting an aralkyl alcohol or the like with a phenol with a Friedel-Crafts catalyst, also called a Friedel-Crafts resin, such as Xyloc resin (trade name, manufactured by Albright & Wilson). For example, xylylene glycol, xylylene glycol dimethyl ether, xylylene glycol diethyl ether,
Although it can be obtained by reacting xylylene glycol diacetoxy ester and the like with phenol, a condensate of p-xylylene glycol dimethyl ether and phenol is particularly well known.

[0018]

Embedded image

The phenolic curing agent (b) of the present invention comprises the above-mentioned addition condensate (1) of a phenol and an aromatic aldehyde.
And phenol aralkyl resin (2)
Used as a mixture . Both blending ratio ranges from 25/75 to 85/15 in a weight ratio of addition condensate / phenol aralkyl resin of a phenol and the aromatic aldehyde. In addition condensate of a phenol and the aromatic aldehyde is less than 25 wt%, without increasing the glass transition point is too, it can not satisfy the object of the present invention. If additional condensate of a phenol and the aromatic aldehyde is higher than 85 wt% is also cured product obtained by curing the addition of epoxy resins tend to slightly hard and brittle.

In the present invention, a known curing agent such as phenol novolak resin or tris (hydroxyphenyl) methane can be used in combination with a known curing agent as long as the effect is not impaired.

The compounding ratio of (b) the phenolic curing agent to (a) the epoxy resin is in the range of 0.8 to 1.2 in terms of chemical equivalent ratio in view of heat resistance, moisture resistance and mechanical characteristics. Is preferred.

The curing accelerator (c) used in the present invention is not particularly limited as long as it accelerates the curing reaction between the epoxy resin and the phenolic curing agent. For example, imidazoles such as 2-methylimidazole, 2,4-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, and tri (p
Organic phosphine compounds such as methylphenyl) phosphine and triphenylphosphine.

These hardening accelerators may be used depending on the purpose.
Seeds, or two or more kinds may be used in combination,
(A) 0.2 to 5 parts per 100 parts by weight of epoxy resin
The range of parts by weight is preferred in terms of curing characteristics and physical properties.

The inorganic filler (d) used in the present invention includes fused silica, crystalline silica, alumina, glass, calcium silicate, gypsum, calcium carbonate, magnesite, clay, kaolin, talc, mica, magnesia,
Among them, fused silica and crystalline silica are most preferable in terms of high purity and low coefficient of thermal expansion.

The amount of the inorganic filler to be added is preferably in the range of 60 to 9 based on the total amount of the resin composition for semiconductor encapsulation of the present invention.
It is preferably 0% by weight. If the amount of the inorganic filler is less than 60% by weight, the solder heat resistance and the coefficient of linear expansion are insufficient. If it exceeds 90% by weight, the fluidity of the molded product becomes insufficient.

With regard to the particle size distribution of the inorganic filler, close-packing is performed by appropriately setting the distribution by combining coarse particles and fine particles, and the addition of the inorganic filler can be performed without impairing the fluidity during molding. The amount can be increased.

The composition for encapsulating a semiconductor according to the present invention may contain, if necessary, a release agent such as a natural wax, a synthetic wax, a metal salt of a linear fatty acid, an acid amide, an ester or a paraffin. Flame retardants such as halogen compounds and phosphorus compounds such as chlorinated paraffin, bromotoluene, hexabromobenzene, and halogenated epoxy resins; flame retardant aids such as antimony trioxide; coloring agents such as carbon black; silane coupling agents May be appropriately added and blended.

As a general method for preparing the resin composition for semiconductor encapsulation of the present invention as a molding material, a raw material component selected in a predetermined composition ratio is sufficiently mixed by, for example, a mixer, and then further heated. It can be easily obtained by adding a kneading treatment with a kneader or a kneader.

[0029]

The present invention will be specifically described below with reference to examples. [Production Example 1] (Production of addition condensate A and phenol and benz aldehyde) stirrer, a thermometer, a condenser, and a four-necked flask equipped with a nitrogen gas inlet tube, a phenol 470 parts by weight,
265 parts by weight of benzaldehyde and 1 part by weight of p-toluenesulfonic acid (monohydrate) were added, the mixture was heated to 140 ° C., and the reaction was carried out while dehydrating until no generation of condensed water was observed. After removing p-toluenesulfonic acid in the system by washing with water, unreacted phenol was removed by distillation under reduced pressure to obtain the desired product. The obtained addition condensate had a softening point of 70 ° C. and a hydroxyl equivalent of 158 g / eq.

[Production Example 2] (Production of addition condensate B) Orthocresol 540 parts by weight, benzaldehyde 265 parts by weight, p-toluenesulfonic acid (monohydrate) was added to the apparatus used in Production Example 1.
One part by weight was added, the mixture was heated to 140 ° C., and the reaction was carried out while dehydration was performed until generation of condensed water was no longer observed. Thereafter, unreacted cresol in the system was removed by distillation under reduced pressure to obtain the desired product. The obtained addition condensate had a softening point of 73 ° C. and a hydroxyl equivalent of 172 g / eq.

[Production Example 3] (Production of addition condensate C) Using the apparatus used in Production Example 1, 575 parts by weight of 1-naphthol, 210 parts by weight of benzaldehyde, p-toluenesulfonic acid (monohydrate) 1 The mixture was heated to 140 ° C., and the reaction was performed while dehydration was performed until generation of condensed water was no longer observed. Thereafter, the reaction product was dissolved in dichloromethane, washed with water, and then the solvent and unreacted 1-naphthol were removed from the organic layer by steam distillation under reduced pressure to obtain the desired product.
The obtained addition condensate had a softening point of 85 ° C. and a hydroxyl equivalent of 208 g / eq.

[Production Example 4] (Phenol and naphthoalde
Production of Addition Condensate D with Hyd) Using the apparatus used in Production Example 1, 470 parts by weight of phenol, 390 parts by weight of 1-naphthaldehyde, and 1 part by weight of p-toluenesulfonic acid (monohydrate) were added. The reaction was carried out while heating to 140 ° C. and performing dehydration until generation of condensed water was not observed. Thereafter, unreacted phenol in the system was removed by distillation under reduced pressure to obtain the desired product.
The obtained addition condensate had a softening point of 82 ° C. and a hydroxyl equivalent of 195 g / eq.

Examples 1 to 5 The phenols obtained in Production Examples 1 to 4 and benzaldehyde
A mixture of an addition condensate A to D with phenol or arphthaldehyde and a phenol aralkyl resin (a condensate of p-xylylene glycol dimethyl ether and phenol, E in Table 1) is used as a curing agent, which is used as an epoxy resin or other resin. And the components shown in Table 2 are mixed at a ratio shown in Table 2. After sufficient premixing, the mixture is kneaded with a mixing roll, cooled, and pulverized to form a molding composed of the intended resin composition for semiconductor encapsulation. The material was obtained. Various properties were measured and evaluated for the sealing material sample thus obtained. Table 2 shows the results.

The properties of these sealing materials were measured by the following methods. (1) Moisture Absorption Rate From the molding material, a molded cured product (50 m in diameter)
m, thickness 3 mm) by low-pressure transfer molding at 175 ° C. × 150 seconds, then 150 ° C. × 2 hours + 1
Post cure at 80 ° C. × 6 hours was performed. The test piece was treated in a constant temperature / humidity chamber of 80 ° C./90% humidity for 96 hours, and the moisture absorption was measured.

(2) Glass transition point From the molding material, a cured product of 5 × 5 × 2 mm (molding conditions: 1)
75 ° C. × 150 seconds, post-curing conditions: 150 ° C. × 2 hours + 180 ° C. × 6 hours), and the glass transition point was determined by the TMA method.

(3) Solder heat resistance The molding material was subjected to low-pressure transfer molding under the conditions of 175 ° C. × 150 seconds, and a semiconductor device (6.7 mm × 6.7) for testing was used.
mm), 150 ° C. × 2 hours + 180 ° C. × 6
Time post cure. This test element is
After a 96-hour treatment in a constant temperature / humidity bath of 90 ° C./90% humidity, the rate of occurrence of cracks when immersed in a 260 ° C. solder bath for 10 seconds was checked.

Comparative Examples 1-4 Phenol aralkyl resins as phenolic curing agents
(E) , phenol novolak resin (F) and phenol
Using Le and addition condensate between benz aldehyde (A) singly, and epoxy resins and other compounding agents in the same manner as in Example, in proportions shown in Table 3, a molding material was prepared for sealing The physical properties of the obtained materials were measured in the same manner as in Examples 1 to 5. Table 3 shows the results.

As is evident from the results in Tables 2 and 3, phenols and benzaldehyde or naphtha were used as curing agents.
In Examples 1 to 5 in which an addition condensate of aldehyde and a phenol aralkyl resin were used in combination, the moisture absorption rate was low,
The glass transition point showed a high value. The occurrence of cracks after immersion in the solder bath was very small.

On the other hand, in Comparative Example 1 in which only a phenol aralkyl resin was used as the curing agent, the moisture absorption was low, but the glass transition point was low, and the solder heat resistance was inferior to any of the examples. In Comparative Examples 2 and 3, in which only a phenol novolak resin was used as the curing agent, although the glass transition point was high, the moisture absorption was large, and many cracks occurred during solder immersion. Further phenols and benz aldehyde <br/> de Comparative Example 4 In moisture absorption using only addition condensate of, glass transition point, is inferior to the molding compositions of the present invention the resin composition in the solder heat resistance both.

[0040]

EFFECT OF THE INVENTION Phenols and benzaldehyde or
An addition condensate with naphthaldehyde and a resin composition of the present invention using a mixture of a phenol aralkyl resin as a curing agent have both low hygroscopicity and a high glass transition point,
When used for encapsulation of a semiconductor device, it is extremely excellent in terms of solder heat resistance and reliability, and therefore has extremely great industrial value as an encapsulation material for electronic circuit components.

[0041]

[Table 1]

[0042]

[Table 2]

[0043]

[Table 3]

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-5-97974 (JP, A) JP-A-2-58523 (JP, A) JP-A-5-97946 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) H01L 23 / 29,23 / 31

Claims (1)

(57) [Claims] 1. A resin composition comprising (a) an epoxy resin, (b) a phenolic curing agent, (c) a curing accelerator, and (d) an inorganic filler, as an essential component,
(B) a phenolic curing agent comprising phenols and benz;
Addition condensate with aldehyde or naphthaldehyde (1)
And the phenol aralkyl resin (2) with (1) / (2)
A resin composition for semiconductor encapsulation, which is a mixture mixed at a compounding ratio (weight ratio) of 25/75 to 85/15 .