JPH044214A - Production of resin for sealing semiconductor - Google Patents

Abstract

PURPOSE:To obtain the subject resin, good in compatibility and excellent in moisture and heat resistance, low stress characteristics and reliability after dipping thereof in solders by reacting polymaleimide with a varnish of a polysiloxane prepared by a specific method under specified conditions. CONSTITUTION:The objective resin is obtained by initially reacting a diglycidylpolysiloxane expressed by formula I (R1 is alkylene or phenylene; R2 and R3 are alkyl or phenyl; n is 1-100) with a diaminopolysiloxane expressed by formula 11 (n' is n) at (1.2:1)-(0.8:1) molar ratio in the presence of 10-70wt.% allylated phenolic resin expressed by formula III [a to c are percentages of respective units and numbers of 1-100, provided that (a+b+c) is 100] until the rate of reaction attains >=80% and then reacting 100 pts.wt. polymaleimide with 10-100 pts.wt. varnish of the polysiloxane prepared by the aforementioned reaction until the melting point of the produced resin attains 50-120 deg.C.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is directed to the production of a resin for semiconductor encapsulation that has a high glass transition point (hereinafter referred to as Tg), has poor moisture resistance and compatibility, and has excellent low stress characteristics. It is about the method.

(Prior Art) In recent years, epoxy resin compositions have been commonly used for sealing semiconductor elements such as ICs, LSIs, transistors, diodes, and electronic circuits from the viewpoint of characteristics, cost, and the like.

However, as electronic components are becoming more mass-producible, more highly integrated, and more surface-mounted, demands on sealing resins are becoming more severe.

In particular, chips become larger due to higher integration, packages become thinner, and solder immersion (200 to 300°C) during surface mounting is required.
), which makes it easy for devices to crack, and in order to improve reliability, it is strongly desired that resins for semiconductor encapsulation have low stress characteristics and heat resistance.

Epoxy resin is currently the mainstream resin for semiconductor encapsulation, but there are limits to its improvement in terms of heat resistance as long as epoxy resin is used, and it is difficult to obtain a highly reliable product after solder immersion during surface mounting. Not yet.

In order to cope with these solder heat resistance, it is desired that the resin properties be low stress and high Tg that is higher than the solder bath temperature.

Maleimide resins are attracting attention as a resin with high heat resistance to replace epoxy resins, but amine-modified maleimide resins obtained by the reaction of bismaleimide and aromatic diamines have excellent heat resistance during drying. but,
It has a high water absorption rate, and cracks occur when immersed in solder when moisture is absorbed, resulting in poor reliability.

Other maleimide resins include examples in which polymaleimide and alkenyl phenols or alkenyl phenyl ethers are reacted in the presence of a polymerization catalyst (Japanese Patent Application Laid-Open No.
2-994.58-117219.61-95012.
62-11716.63-230728), but like the amine-modified maleimide resin, the cured product is hard, so it has the disadvantage of poor low stress properties.

Attempts have been made to add various silicone compounds as a measure to improve low-stress properties, but they have significantly poor compatibility, reduced strength, high water absorption, lack moisture resistance and reliability, and have many practical problems. remain.

(Problems to be Solved by the Invention) The object of the present invention is to have good compatibility, excellent moisture resistance, low stress characteristics, and high heat resistance without deteriorating general characteristics, and to have solder immersion resistance. It is an object of the present invention to provide a method for producing a resin for semiconductor encapsulation that has excellent subsequent reliability.

(Means for Solving the Problems) The present invention comprises (A) 100 parts by weight of polymaleimide, and (B)
) A diglycidyl polysiloxane represented by the following formula (I) and a diamino polysiloxane represented by the following formula (II), (R□: alkylene group or phenylene group R2, R3: alkyl group or phenyl group n, n ' = integer of 1 to 100) molar ratio is 1.2:1 to 0.8:l, and the following formula (III)
In the presence of 10 to 70% by weight of an allylated phenolic resin having the composition (0<a, b, c<100, a+b+c=1
00a, b, and c indicate the percentage of each composition. )...(I
) A semiconductor encapsulation characterized by reacting 10 to 100 parts by weight of a polysiloxane varnish obtained by the reaction until the reaction rate reaches 80% or more, and until the melting point of the resulting resin reaches 50 to 120°C. This is a method for producing a stopper resin.

(Function) Specific examples of the polymerimide used in the present invention include N, N'-m-phenylene bismaleimide,
N, N'-p-phenylene bismaleimide, N, N'-
m-Toluylene bismaleimide, N,N'-4,4'-
Biphenylene bismaleimide, N,N'-4,4'-(
3,3'-dimethyl-biphenylene bismaleimide, N
, N'-4,4'-(3,3'-dimethyldiphenylmethane) bismaleimide, N, N'-4,4'-(3,3
'-diethyldiphenylmethane]bismaleimide, N,
N'-4,4'-diphenylmethane bismaleimide, N
, N'-4,4'-diphenylpropane bismaleimide, N, N'-4,4'-diphenyl ether bismaleimide, N, N'-3,3'-diphenylsulfone bismaleimide, N, N'-4, Examples include 4'-diphenylsulfone bismaleimide, a polyfunctional maleimide represented by (IV) or (V), and the like. These are 2
There is no problem even if it contains more than one species.

(R5 knee H, alkyl group or phenyl group 0<i<10
) (0<j<10) The diglycidyl polysiloxane used in the present invention is a polysiloxane represented by the following formula (I), and its degree of polymerization n is in the range of 1 to 100.

...(I) The R group is generally an alkylene group having 1 to 6 carbon atoms or a phenylene group, and R2 and R3 are generally an alkyl group having 1 to 4 carbon atoms or a phenyl group.

The diamino polysiloxane used in the present invention has the following formula [! I], and its degree of polymerization n' is in the range of 1 to 100.

R, R2, and R3 are the same as above.

If the degree of polymerization n of these bifunctional polysiloxanes is 100 or more, the compatibility will be extremely reduced.

The allylated phenol resin used in the present invention is obtained by reacting a phenol resin with allyl chloride or allyl bromide to allylate it, and has the composition of the following formula (III), and has each structure in the resin. The total number of parts present in the ratio of a, b, and c.

(0<a, b, c<100k a+b+c=100a,
(b, c indicate the percentage (%) of each composition) Preferably,
20≦a≦80.10≦b≦50.

Component C is effective in improving heat strength and lowering water absorption, but in the resin production reaction with polymaleimide,
Since there is almost no reaction, if the amount is too large, the resin will not solidify, resulting in poor compatibility and workability.

Component b is an important component that reacts with maleimide groups in the resin production reaction with polymaleimide and improves the compatibility between polymaleimide and polysiloxane. However, if the amount is too large, the number of phenolic hydroxyl groups in the cured product increases, resulting in an increase in water absorption, which is not preferable.

The smaller the C component, the better.

The reaction between diglycidyl polysiloxane and diamino polysiloxane is carried out in a molar ratio of 1.2:1 to 0.8:1, preferably 1:1, in the presence of 10 to 70% by weight of an allylated phenolic resin. At a temperature of 200°C, the reaction rate is 80
It is better to do this until it reaches % or more. If the amount of diglycidyl polysiloxane is too large, the compatibility with the polymaleimide will deteriorate, leading to poor appearance and decreased mechanical strength of the molded product. If the amount of diaminopolysiloxane is too large, the storage stability of the molding material will be significantly deteriorated and the water absorption rate will also increase. The allylated phenolic resin acts as an excellent catalyst in the reaction of the diglycidylpolysiloxane with the diaminopolysiloxane and reacts with the polymaleimide in the next step. If it is less than 10% by weight, the viscosity of the reacted polysiloxane increases, making handling difficult. If it exceeds 70% by weight, the mechanical strength and Tg
, leading to a decrease in low stress properties. If the reaction rate between diglycidylpolysiloxane and diaminopolysiloxane is less than 80%, the compatibility with the polymaleimide will be insufficient, which will adversely affect the storage stability of the molding material, the appearance of the molded product, and various physical properties.

The reaction conditions for the reaction between the thus obtained polysiloxane varnish (B) and the polymaleimide (A) are not particularly limited.
This can be carried out by heating to 0° C. and adding (A) thereto. The amount of polysiloxane varnish is 10 to 100 parts by weight, preferably 30 to 90 parts by weight, per 100 parts by weight of polymaleimide.
Good weight section. If it is too small, low stress characteristics cannot be obtained.

If it is too large, the mechanical strength and Tg will decrease and cracks will occur during solder immersion.

The end point of the reaction is when the melting point of the obtained resin is 50 to 120°C.
It is preferable to carry out the process until . In addition, in order to confirm the end point of the reaction, a small amount of resin is taken out from the reaction system, cooled, and the melting point is measured and confirmed.

In order to make a molding material using the obtained resin, epoxy resin, hardening accelerator, inorganic filler, lubricant, flame retardant, mold release agent, silane coupling agent, etc. are appropriately blended with this resin. The added and uniformly mixed composition is subjected to cross-crossing treatment using a kneader 1 heated roll or the like, cooled, and then pulverized to obtain a molding material.

If the obtained molding material is used for encapsulating semiconductors, high T
In addition, it is possible to obtain a resin composition for semiconductor encapsulation which has excellent low stress characteristics and is highly reliable.

[Synthesis of allylated phenolic resin] Synthesis example In a reaction vessel equipped with a stirring device, reflux condenser, thermometer and dropping funnel, 76 parts by weight of potassium hydroxide and 500 parts by weight of a mixed solvent of water/acetone (1/1) were added. 100 parts by weight of a phenol resin PR-51470 (manufactured by Jujurez ■) was added and dissolved.

This solution was heated, 122 parts by weight of allyl bromide was added, and the mixture was reacted under reflux for 3 hours. Then, neutralize with hydrochloric acid,
Acetone and unreacted allyl bromide were distilled off, and 1 liter of toluene was added. The mixture was transferred to a separating funnel, washed with water three times, and the solvent was removed using an evaporator.

Further, heat treatment was performed at 175° C. for 52 hours to obtain an allylated phenol resin. The composition of the product is (Example) Examples 1 to 2 Diglycidyl polysiloxane, diamino polysiloxane, and allylated phenolic resin were placed in a reaction vessel equipped with a stirring device, a pressure reduction device, and a thermometer according to the recipe in Table 1. The reaction was carried out under reduced pressure (approximately 20 mmHg) at 150°C until the reaction rate of glycidyl groups reached 90%. The reaction time was approximately 30 minutes.

Polymaleimide was added to this, and the mixture was reacted for an additional 30 minutes. The obtained silicone-modified maleimide resin was homogeneous and its melting point is shown in Table 1.

Comparative Examples 1 to 2 In Comparative Example 1, the molar ratio (Jig "fucidyl polysiloxane/diaminopolysiloxane)" of Example 1 was set to 173, and in Comparative Example 2, the allylated phenol resin of Example 1 was set to 0,0'-
The reaction was carried out in the same manner except that diallylbisphenol A was used instead.

Comparative Example 3 The allylated phenol resin of Example 1 was replaced with bisphenol A diallyl ether, and the reaction was carried out in the same manner.

The reaction between allyl ether and maleimide group is very slow,
The resulting resin was heterogeneous and liquid components were exuding. Note that when the reaction was carried out at an even higher temperature (200°C), heat was rapidly generated and gelation occurred, making it difficult to control the reaction.

Comparative Example 4 Degree of polymerization (n) of diglycidyl polysiloxane of Reference Example 1
was made larger and the reaction was similar. It had poor compatibility with polymaleimide, and the oily polysiloxane separated and oozed out, resulting in non-uniformity.

Examples 3-4 As shown in Table 2, the silicone-modified maleimide resin obtained in Examples 1-2 was blended with silica powder, a curing accelerator, an aminosilane, a coloring agent, and a mold release agent, and kneaded with a hot roll. A molding material was obtained. The obtained molding material was molded by transfer molding at 180° C. for 13 minutes to obtain a glossy molded product without blisters. Add this molded product to 180
After curing at °C for 18 hours, the properties were evaluated. Second result
Shown in the table.

The molding materials of Examples 3 and 4 using the resins of Examples 1 and 2 have a lower flexural modulus at room temperature, lower stress, and lower internal stress than Comparative Example 10 that does not contain silicone. Moreover, it has a high glass transition temperature, high bending strength at 260°C, excellent heat resistance and solder crack resistance, and low water absorption.

Comparative Examples 5-10 For comparison with Examples 3-4, molding materials were prepared and molded in the same manner as shown in Table 2.

Comparative Example 5 uses a silicone-modified maleimide resin having a molar ratio (diglycidylpolysiloxane/diaminopolysiloxane) of 1/3 of Comparative Example 1. Heat resistance is reduced, water absorption is high, and solder crack resistance is also poor.

In Comparative Example 6, the allylated phenol resin of Example 1 was added to 0.
The reaction was carried out by substituting 0'-diallylbisphenol A. The silicone-modified maleimide resin of Comparative Example 2 was used.

Similar to Comparative Example 5, the heat resistance and water absorption rate are poor.

In Comparative Example 7, the allylated phenol resin of Example 1 was replaced with bisphenol A-diallyl ether and the reaction was carried out. The silicone-modified maleimide resin of Comparative Example 3 was used.

The appearance of the shaped product is poor, the mold becomes cloudy, and the water absorption rate is high.

Comparative Example 8 has almost the same composition as Example 3, but was simply mixed at the time of blending. Similar to Comparative Example 7, the appearance of the molded product was poor, the mold was cloudy, and the water absorption rate was high.

Comparative Example 9 uses polysiloxane with a high degree of polymerization (n), but has poor compatibility with polymaleimide.
Similar to Comparative Example 7.8, favorable results were not obtained.

Comparative Example 10 does not contain polysiloxane.

Although the appearance, bending strength, and heat resistance of the molded product are good, the water absorption rate is large and the solder crack resistance is insufficient.

(Effects of the Invention) The cured product of the composition using the resin for semiconductor encapsulation according to the present invention has a high Tg and is excellent in moisture resistance and strength under heat, so that the encapsulated body has good solder crack resistance. It also has low stress and excellent heat cycle resistance, making it an excellent and highly reliable resin composition for semiconductor encapsulation.

Claims (1)

[Claims] (1) (A) 100 parts by weight of polymaleimide, (B) diglycidylpolysiloxane represented by the following formula [I], and diaminopolysiloxane represented by the following formula [II], ▲Mathematical formula, chemical formula, table etc.▼ ・・・[I] ▲Mathematical formulas, chemical formulas, tables, etc.▼・・・[II] (R_1: Alkylene group or phenylene group R_2, R_3: Alkyl group or phenyl group n, n':
(an integer from 1 to 100) in the presence of 10 to 70% by weight of an allylated phenolic resin having a molar ratio of 1.2:1 to 0.8:1 and having a composition of the following formula [III], ▲Mathematical formula, chemical formula , tables, etc. ▼, ▲ mathematical formulas, chemical formulas,
There are tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼
...[III] (0<a, b, c<100 and a+b+c=100a,
b and c indicate the percentage of each composition. ) Semiconductor encapsulation characterized by reacting 10 to 100 parts by weight of polysiloxane varnish obtained by the reaction until the reaction rate reaches 80% or more, and until the melting point of the resulting resin reaches 50 to 120°C. Method of manufacturing resin for use.