JPS60190418A - Liquid epoxy resin composition for sealing semiconductors - Google Patents

Abstract

PURPOSE:The titled composition that contains, as a curing agent, an acid anhydride and a phenolic resin, thus showing improved low-pressure pourability and curability and giving cured products with high resistance of moisture and hydrolysis. CONSTITUTION:(A) An acid anhydride such as methyltetrahydrophthalic anhydride is combined with (B) a phenolic resin of low polymerization degree such as a phenol novolak resin at an quivalent ratio of 0.3-0.7 A/B to prepare a curing agent. The agent is mixed with an epoxy resin such as bisphenol-A epoxy resin, preferably in an amount of 0.4-1.2 equivalent per equivalent of the epoxy groups and an inorganic filler such as crystalline silica and a coupling agent such as gamma-glycidopropyl trimethoxysilane, preferably in an amount of 0.1- 3pts.wt., per 100pts.wt. of the filler, further a curing accelerator such as an imidazole is added to give the objective composition.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a liquid epoxy resin composition for semiconductor encapsulation that has excellent moisture resistance and reliability and also has excellent low pressure injectability.

[Prior art] Currently, resin encapsulation methods with excellent mass productivity, in which semiconductor elements such as 1C1L8 are embossed using silicone resin or epoxy resin, are widely used. Among these, epoxy resin is relatively superior. It is widely used as a resin for semiconductor encapsulation because it provides airtightness and is inexpensive.

Conventional epoxy resin compositions for semiconductor encapsulation contain epoxy resins, curing agents, curing accelerators, inorganic fillers, etc.
The mixture was uniformly mixed using roll mixing, etc., and then turned into powder, which was then molded into tablets and used for semiconductor encapsulation. In order to seal the semiconductor element, the preheated tablet is placed in the cylinder of a molding machine, heated and melted at a high temperature, and then placed in a heated mold with a pressure of 50K9/cd or higher. It was injected with heat and hardened.

There have been various problems in encapsulating semiconductor elements using such conventional semiconductor encapsulating resin compositions. Namely, resin usage efficiency is low due to high pressure molding, and expensive mold clamping presses are required. In addition, the use of high-voltage resistant molds is required, and in addition, semiconductor device wiring and bonding lines may be deformed or misaligned.
This often caused wire breakage, resulting in a decline in product characteristics and yield.

Under these circumstances, efforts have been made to develop various liquid semiconductor encapsulation resins, but they have not yet been put to practical use in applications that require high reliability.

The biggest reason for this is that among these 4σ1 resins, if liquid semiconductor encapsulation resins are used, the above-mentioned drawbacks can be reduced to almost 1.
This is because the moisture resistance may not be sufficient in some cases.

That is, when a liquid epoxy resin composition containing an amine-based curing agent is used as a liquid semiconductor encapsulation resin, the amine-based curing agent is inherently highly reactive, and the normal pressure injectability deteriorates in a short period of time after compounding. Instead, it promotes corrosion of the aluminum wiring of semiconductor devices, leading to a short-term decrease in moisture resistance.

Furthermore, even when a phenolic resin-based cured AIJ liquid epoxy resin composition is used, the reaction between the phenolic hydroxyl group and the epoxy group produces a strongly hydrophilic alcoholic hydroxyl group, which leads to the formation of hydrogen bonds between the phenolic hydroxyl groups. Therefore, it tends to become semi-solid and has poor low-pressure injectability.To improve this, modifiers such as low-molecular phenol compounds and diluents are usually added. This leads to a decrease in various properties, and also a decrease in moisture resistance in a short period of time.

On the other hand, when a liquid epoxy resin composition containing an acid anhydride curing agent is used, a large amount of a low-viscosity acid anhydride can be blended, so the viscosity of such a resin composition is extremely low, and low-pressure injection is possible. . Therefore, it is not necessary to mix a modifying agent such as a diluent to lower the viscosity, and various properties such as heat distortion temperature do not deteriorate. However, the ester bonds of epoxy resins cured using acid anhydrides as curing agents gradually undergo hydrolysis under high temperature conditions, resulting in poor moisture resistance over a relatively long period of time.

Therefore, it can be applied to LSI, VI, and S engineering, which will require increasingly high mixing resistance and miniaturization in the future, and has excellent moisture resistance and
At present, there is a strong desire to develop a liquid epoxy resin composition for semiconductor encapsulation that has excellent hydrolysis resistance, low-pressure injection properties, and curability.

[Summary of the Invention] This invention was made to eliminate the drawbacks of the above-mentioned conventional products. The object of the present invention is to provide a liquid epoxy resin composition for semiconductor encapsulation that has excellent low-pressure injection properties, curability, and moisture resistance reliability by using a composition containing an accelerator.

[Embodiments of the Invention] Examples of epoxy resins according to the present invention include bisphenol A-based epoxy resins, phenol novolac epoxy resins, cresol novolac-based epoxy resins, and alicyclic epoxy resins having two or more epoxy groups in the molecule. At least one of these is used. In addition, in addition to these epoxy resins, solid epoxy resins such as brominated novolac epoxy resins and brominated bisphenol A epoxy resins can also be used in combination, if necessary.

Examples of the acid anhydride of the curing agent according to the present invention include phthalic anhydride, tetranohydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylbexanohydrophthalic anhydride, and inctaric acid. Preference is given to using methyltetrahydrophthalic anhydride and methylbexahydrophthalic anhydride which are liquid, especially at room temperature. Further, these acid anhydrides can be used alone or in combination of two or more.

Examples of the phenolic resin of the curing agent according to the present invention include bisphenol A, trimethylolallyloxyphenol, phenol novolac resin with a low degree of polymerization, and gtylated phenol resin.

Further, the mixture of acid anhydride and phenol resin used as a curing agent is in the range of 0.4 to 1.2 equivalents, preferably 0.6 to 1.0 equivalents, per 1 equivalent of the epoxy group of the epoxy resin. It is preferable to use the acid anhydride (A, A,
/phenol resin (Ph) = 0.3 to 7.0, preferably 0.6 to 4.5.

If the amount of the mixed curing agent is less than 0.4 equivalent, the heat distortion temperature of the cured product will decrease, resulting in a decrease in moisture resistance. On the other hand, if the amount exceeds 1.2 equivalents, the moisture resistance will be lowered due to the influence of the mixed curing agent of the additive, which is not preferable.

'Furthermore, if the mixing ratio of acid anhydride and phenolic resin is less than 0.3, the sealing material will solidify, resulting in poor low-pressure injection properties.7.
If it is larger than 0, the moisture resistance will be poor.

Examples of the inorganic filler according to the present invention include crystalline silica, fused silica, alumina, and glass fiber, but it is particularly preferable to use fused silica because of its excellent filling properties and purity. These fillers can be used alone or in combination of two or more, and the amount used depends on the specific type, but in general, epoxy resin containing a curing agent
The range of 100 to 600 parts by weight is preferable relative to 0 parts by weight.

If it is less than 100 parts by weight, the expansion coefficient will be large and the crank resistance will be poor, and if it is more than 600 parts by weight, the viscosity will be high and the low pressure injection properties will be poor. Incidentally, it is also possible to add a flame retardant aid such as antimony trioxide if necessary.

Coupling agents of the present invention include silane compounds such as T-glycidoxypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, vinyltri-2-methoxysilane, and phenyltrimethoxysilane. r-glycidoxypropyltrimethoxysilane, β-(3,4-
epoxycyclohexyl)ethyltrimethoxysilane,
It is preferable to use phenyltrimethoxysilane, which has excellent hydrophobicity. These coupling agents can be used alone or in combination of two or more, and the amount used is 0.1 to 3 parts by weight, preferably 0.2 to 2 parts by weight, per 100 parts by weight of the filler.
Parts by weight range. If it is less than 0.1 part by weight, the adhesion between the filler and the epoxy resin will be poor, leading to a decrease in moisture resistance, and if it is more than 3 parts by weight, the coupling agent in the filler will accelerate the deterioration of the resin, resulting in a decrease in moisture resistance. bring about.

Examples of the curing accelerator according to the present invention include imidazole compounds and tertiary amines.

Further, the liquid epoxy resin composition for semiconductor encapsulation of the present invention can also contain a colorant such as carbon blank, and a mold release agent such as carnauba wax and synthetic wax, if necessary.

The liquid epoxy resin composition for semiconductor encapsulation of the embodiments of the present invention can be prepared by using a known mixing device, such as a roll, kneader, or light machine, which is used in the preparation of conventional semiconductor encapsulation materials. Easy to prepare.

The present invention will be explained in more detail below with reference to Examples and Comparative Examples.

(9) Table IK shows the resin composition used in Examples and Comparative Examples. A liquid epoxy resin composition for semiconductor encapsulation was prepared by a conventional method.

Table 2 shows the viscosities of these prepared compositions as measured with a B-type rotational viscometer at 50°C.

Furthermore, a silicon element for moisture resistance evaluation was molded using the prepared composition under molding conditions of 170° C. for 3 minutes, and further cured at 170° C. for 8 hours to obtain a sample for moisture resistance test.

Humidity test 1d P CT (Pressur Cook
The results are shown in Table 3.

Note that Comparative Example 12 did not become liquid and could not be molded with a low-pressure injection molding machine.

As is clear from Table 2, since the composition of the present invention is liquid, low-pressure injection is possible, and as is clear from Table 3, it also has excellent moisture resistance reliability.

(lO) (11) Table 3 After curing, a sample for moisture resistance test was obtained.

Humidity test 1d P CT (Pressur Cooke
rTe5t) Measured by the failure occurrence time under conditions of 121°C and 2 atm (12), and the results are shown in Table 3.

Note that Comparative Example 12 did not become liquid and could not be molded with a low-pressure injection molding machine.

As is clear from Table 2, since the composition of the present invention becomes a liquid, low-pressure injection is possible, and as is clear from Table 3, it is also found to have excellent moisture resistance reliability.

[Effects of the Invention] As explained above, the present invention provides a mixture of an epoxy resin, an acid anhydride as a curing agent, and a phenol resin,
By using a composition containing an inorganic filler, a coupling agent, and a curing accelerator, it is possible to obtain a liquid epoxy resin composition for semiconductor encapsulation that has excellent low-pressure injectability, curability, and moisture resistance reliability. It is useful as a resin for sealing semiconductor devices such as PCB and LSI.

Agent Masuo Oiwa (13) Continued from page 1 [Phase] Int, C1,' Identification code Internal reference number 0 Inventor Torahiko Ando Inside the Tsukaguchi Honmachi Institute, Amagasaki City

Claims (1)

[Scope of Claims] (]) A liquid epoxy resin composition for semiconductor encapsulation, which contains an epoxy resin, a mixture of an acid anhydride and a phenol resin as a curing agent, an inorganic filler, a camping agent, and a curing accelerator. (2) For semiconductor encapsulation according to claim 1, wherein the equivalent ratio of acid anhydride and phenolic resin in the curing agent mixture is in the range of acid anhydride/phenol resin = 0.3 to 7.0. Liquid epoxy resin composition. (3) The liquid epoxy resin composition for semiconductor encapsulation according to claim 1 or 2, wherein the acid anhydride is at least one of methyltetrahydrophthalic anhydride and methylhexahydroheptalic anhydride. thing.