JPH04328117A - Epoxy resin composition for sealing semiconductor - Google Patents

Abstract

PURPOSE:To provide a composition composed of a polyfunctional epoxy com pound, a phenolic novolak resin, an inorganic filler, a cure accelerator and a specific polyether sulfone and having excellent heat-resistance, cold and heat shock resistance, toughness, high-temperature mechanical strength, etc. CONSTITUTION:This composition is composed of (A) a polyfunctional epoxy compound, (B) a phenolic novolak resin, (C) an inorganic filler (e.g. crystalline silica powder), (D) a cure accelerator (e.g. 2-methylimidazole) and (E) a polyether sulfone having terminal amine group or terminal phenol group and expressed by formula I ((x) and (y) are positive number; (x+y) is 1-50; R1 is group of formula II and R2 is group of formula III or formula IV in the case of amine- terminated polyether sulfone, and R1 is H and R2 is OH in the case of phenol- terminated polyether sulfone). Preferably, the components A and E are reacted with each other in advance and the preliminary reaction product is compounded to the other components.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel epoxy resin composition for encapsulating semiconductors which has excellent cold shock resistance, heat resistance and toughness.

0002

[Prior Art] Currently, resin encapsulation methods are widely used to encapsulate semiconductor devices such as ICs and LSIs using silicone resins or epoxy resins. Of these, epoxy resins offer relatively excellent airtightness. , and because it is inexpensive, it is widely used as a resin for semiconductor encapsulation.

However, due to the diversification of mounting methods for ICs and LSIs, resin-sealed packages tend to be smaller and thinner, and smaller and thinner packages have been manufactured using conventional epoxy resins. In this case, since the high-temperature mechanical strength of the epoxy resin is low, cracks occur in the sealing resin after it is dipped into solder after being mounted on a board. In order to prevent this cracking, methods such as dispersing rubber components or engineering plastic components in the epoxy resin matrix or adding silicone oil are being considered. However, with these methods, it is difficult to disperse finely and uniformly in the composition, and the effect is small relative to the amount added, and when the amount added is increased, the fluidity during molding is significantly reduced. In addition, since it is a mixture, undesirable conditions such as peeling at the interface between the epoxy resin matrix and the domain occur, resulting in problems in workability and reliability in crack resistance.

0004

[Problems to be Solved by the Invention] The present invention was made to solve these problems, and the object is to provide cold and thermal shock resistance and heat resistance that do not cause problems such as peeling at the interface between the epoxy resin matrix and the domain. Another object of the present invention is to obtain a novel epoxy resin composition for semiconductor encapsulation that has excellent toughness.

[0005]

[Means for Solving the Problems] The present invention provides a polyfunctional epoxy compound, a phenol novolac resin, an inorganic filler, a curing accelerator, a polyfunctional epoxy compound, and the following general formula.

[0006]

[Chemical 2]

An epoxy resin composition for semiconductor encapsulation characterized by comprising a pre-reactant reacted in advance with a polyether sulfone having an amine group or a phenol group at the terminal shown in the figure below, with or without a catalyst. be.

The polyfunctional epoxy compounds used in the present invention include novolak epoxy resins, bisphenol A epoxy resins, alicyclic epoxy resins, 3,3',
Various types of epoxy resins can be mentioned, such as 5,5'-tetramethylbiphenol type epoxy resin. Note that these epoxy resins may be used alone or in combination of two or more.

Furthermore, an epoxy resin such as a brominated novolak epoxy resin or a brominated bisphenol A epoxy resin may be used in combination with these polyfunctional epoxy compounds, if necessary. In this case, the amount of these epoxy resins used is 5 parts by weight per 100 parts by weight of the polyfunctional epoxy resin.
It is preferably 0 parts by weight or less.

The phenol novolac resin used in the present invention is obtained by condensing a phenol compound such as phenol, cresol, xylenol, bisphenol A, or resorcinol with formaldehyde or paraformaldehyde under an acidic catalyst. It is preferable that the amount of unreacted monomer is 0.5% by weight or less in the obtained phenol novolac resin.

The blending ratio of the polyfunctional epoxy compound, phenol novolac resin, and amine group-terminated or phenol group-terminated polyether sulfone is determined based on the hydroxyl group equivalent of the phenol novolac resin and the amine group-terminated or phenol group-terminated polyether sulfone per equivalent of the epoxy group of the epoxy resin. The total of amine equivalents or hydroxyl group equivalents of ether sulfone is 0
．． Preferably, the amount is 8 to 1.2 equivalents. If it is less than 0.8, the glass transition temperature of the composition will be low, resulting in decreased heat resistance and moisture resistance, and if it exceeds 1.2, a large amount of phenol novolac resin will remain as an unreacted product in the cured product. , moisture resistance and heat resistance will decrease.

Examples of the inorganic filler used in the present invention include crystalline silica powder, fused silica powder, alumina powder, talc, quartz glass powder, calcium carbonate powder, and glass fiber. The amount of these inorganic fillers added is preferably 50 to 85% by weight in the composition. If it is less than 50% by weight, the effect of lowering the coefficient of linear expansion and curing shrinkage will be small, and if it exceeds 85% by weight, fluidity will decrease and workability will tend to decrease.
It is preferable to appropriately select the blending amount in the range of 50 to 85% by weight depending on the required properties.

The amine group- or phenol group-terminated polyether sulfone in the present invention is a component blended to improve toughness and high-temperature mechanical strength, and is present in an amount of 0.1 to 30% by weight based on the polyfunctional epoxy compound. and preferably in the range 10-25% by weight. If it is less than 0.1% by weight, the effect of improving toughness and high-temperature mechanical strength will be reduced, and if it exceeds 30% by weight, the fluidity of the resulting composition will decrease and workability will be impaired, making it unsuitable for practical use.

[0014] The molecular weight of the polyether sulfone is 1,000 to 25,000, and 5,000 to 20,000.
It is preferable that it is in the range of . If it is less than 1,000, the molecular weight will increase during the preliminary reaction with the polyfunctional epoxy compound, and the fluidity of the composition using this will decrease, impairing workability, and the toughness and high-temperature mechanical strength will also decrease. . When it exceeds 25,000, the fluidity of the resulting composition decreases, impairing workability and making it unsuitable for practical use.

[0015] As the curing accelerator and the catalyst for the reaction between the amine group-terminated or phenol-terminated polyether sulfone and the polyfunctional epoxy compound used in the present invention, common ones can be used. For example, imidazole compounds; 2-methylimidazole, 2-phenylimidazole, 2-ethyl-4-methylimidazole, etc.; tertiary amine compounds; tributylamine, triethylamine, benzyldimethylamine, trisdimethylaminophenol, 1,
Organic phosphine compounds such as 8-diazabicyclo(5,4,0)undecene-7; triphenylphosphine,
Examples include tributylphosphine and tri-4-methylphenylphosphine. It is also possible to use these alone or in combination of two or more. The amount of the curing accelerator and the reaction catalyst between the amine group-terminated or phenol group-terminated polyether sulfone and the polyfunctional epoxy compound cannot be determined unconditionally because it varies depending on the type of the compound. Although not limited to this, it is usually preferably 0.02 to 5 parts by weight based on 100 parts by weight of the polyfunctional epoxy resin.

The epoxy resin composition for semiconductor encapsulation of the present invention may optionally contain a coloring agent such as carbon black, a mold release agent such as carnauba wax or polyethylene wax, a flame retardant such as antimony trioxide, and γ-glycide. A coupling agent such as siloxypropyltrimethoxysilane, and a rubber component such as silicone rubber or fluororubber may be added in an amount not exceeding 10% in the composition.

Furthermore, the epoxy resin composition for semiconductor encapsulation of the present invention can be easily prepared using commonly used known mixing devices such as rolls, kneaders, crushers, Henschel mixers, and the like.

According to the present invention, in order to introduce a polyether sulfone domain into an epoxy resin matrix, an amine- or phenol-terminated polyether sulfone is used to react with a part of the polyfunctional epoxy compound used in advance. By keeping the mixture in place, the interface between the matrix and the domains becomes more compatible, and undesirable conditions such as peeling do not occur, making it possible to obtain a composition with excellent cold shock resistance, heat resistance, toughness, etc. The method for reacting the amine group- or phenol group-terminated polyether sulfone with the polyfunctional epoxy compound is as follows: (1) The polyether sulfone and the polyfunctional epoxy compound are reacted under heating and melting. Although the reaction can be carried out without a catalyst, it is also preferable to use an appropriate amount of the reaction catalyst exemplified as a component of the present invention from the viewpoint of shortening the reaction time. ■Use a common good solvent for polyether sulfone and polyfunctional epoxy compound to dissolve both to form a uniform solution. Next, the used solvent was distilled off under reduced pressure, and then dried under reduced pressure to obtain a uniform resin.
React in the same way.

It is also preferable to melt and mix the polyether sulfone and the phenol novolak resin in advance in order to improve flow and dispersibility. moreover,
The flow can also be adjusted by appropriately using a preliminary reaction product of polyether sulfone and a polyfunctional epoxy compound, and a molten mixture of polyether sulfone and a phenol novolac resin.

The present invention will be explained in more detail below using Examples and Comparative Examples, but the present invention is not limited thereto.

[0021]

Examples (Reference Examples 1 to 4) The raw materials and solvents shown in Table 1 were charged into a 3-liter four-necked flask under a nitrogen stream, and heated while stirring. After removing water in the system by azeotropic dehydration with toluene, the reaction was continued for 10 hours while maintaining the system temperature at 190°C. After the reaction, the mixture was neutralized with acetic acid, precipitated in water, and washed several times with methanol. This was dried under reduced pressure to obtain the desired polyether sulfone.

[0022]

[Table 1]

(Examples 1, 2, 3, 4, Comparative Example 1) Table 2
A reaction product of polyfunctional epoxy resin and polyether sulfone was obtained with the composition shown in Table 3, and the composition shown in Table 3 was thoroughly kneaded with a roll at 90 ° C., then cooled and crushed to obtain a sealing resin composition. Ta. Next, this was transfer molded at 175°C for 2 minutes, post-cured at 175°C for 8 hours, and then physical properties were evaluated. Table 3 shows each characteristic value.

[0024]

[Table 2]

[0025]

[Table 3]

[0026]

[Effects of the Invention] As described above, the epoxy resin composition for semiconductor encapsulation of the present invention has excellent mechanical strength and impact resistance when heated,
Therefore, it is clear that the crack resistance during immersion in a solder bath and the subsequent moisture resistance are also excellent.

Claims (3)

[Claims] 1. Semiconductor encapsulation characterized by comprising a polyfunctional epoxy compound, a phenol novolak resin, an inorganic filler, a curing accelerator, and a polyether sulfone having an amine group or a phenol group at the end represented by the following general formula. Epoxy resin composition for use. [Chemical formula 1] 2. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein part or all of the polyether sulfone having an amine group or a phenol group is reacted in advance with a polyfunctional epoxy compound to obtain a preliminary reaction product. 3. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein part or all of the polyether sulfone having an amine group or a phenol group is preliminarily melted and mixed with a phenol novolak resin.