JPS61151234A - Epoxy resin composition for sealing semiconductor - Google Patents

Abstract

PURPOSE:The titled composition which can give resin-sealed semiconductor devices excellent in moisture resistance and reliability, comprising an epoxy resin, a novolak phenolic resin, a silica powder and a specified alkoxymonosilane compound. CONSTITUTION:A 10-25wt% high-purity epoxy resin having at least two epoxy groups in the molecule, an epoxy equivalent weight <=220 and a softening point <=100 deg.C (e.g., bisphenol A epoxy resin) with 5-15wt% novolak phenolic resin, as a curing agent, of a hydroxyl equivalent <=150 and a softening point <=120 deg.C, 65-85wt% silica powder as a filler, 0.02-1.0wt% alkoxy monosilane compound having at least one nonreactive water-repelling group such as an alkyl or an (alkyl-substituted) phenyl group (e.g., methyltrimethoxysilane), etc.

Description

[Detailed description of the invention] [Technical field of invention].

The present invention relates to epoxy resin compositions for encapsulating semiconductor devices, and particularly to provide highly reliable resin-encapsulated semiconductor devices with excellent moisture resistance.

[Technical background of the invention and its problems]

Recent semiconductor devices such as IC, LSI, VLS
I.

Resin encapsulation is often used for transistor diodes due to its advantages in mass production and cost compared to ceramic and can encapsulation types. However, resin-sealed semiconductor devices have inferior moisture resistance compared to ceramic or can-sealed devices, which poses a problem that reduces the reliability of the semiconductor devices.

Therefore, various studies have been conducted to prevent moisture resistance defects in resin-sealed semiconductor devices.

Examples of these improvement methods include adding corrosion inhibitors such as quinones, surface treatment methods such as silane coupling agents to increase the adhesion between the filler surface and resin, and water-repellent wax. There are many ways to mix in.

[Purpose of the invention]

In order to obtain resin-sealed semiconductor devices with good moisture resistance, the present inventors have conducted various studies on epoxy resin compositions as sealing materials for the purpose of improving moisture resistance. The inventors have discovered that a silica-filled epoxy resin composition containing a specific phenolic resin and a specific alkoxysilane gives very good results in improving the moisture resistance of semiconductor devices, leading to the present invention.

[Summary of the invention]

That is, the present invention provides: (a) an epoxy equivalent of 220 or less and a softening point of 10;
10 to 25% by weight of an epoxy resin at 0°C or lower, and (b)
5 to 15% by weight of a novolac type phenolic resin having a hydroxyl equivalent of 150 or less and a softening point of 120°C or less; (c) 65 to 85% by weight of silica powder; (d)
At least one alkyl group, phenyl group.

or 0.02 to 1.0% by weight of an alkoxymonosilane compound having an alkyl-substituted phenyl group.

In the present invention, an epoxy resin composition with good moisture resistance can be obtained by using the above-mentioned components a to d as essential components. Among the above components, a particularly important component is the component d, that is, the specific alkoxy It is a monosilane compound.

Among silicone compounds, silane coupling agents having reactive groups and alkoxy groups are often used for surface treatment of fillers, and are also mixed into epoxy resins to improve adhesion to semiconductor devices and improve moisture resistance. is well known. However, since the silane coupling agent has a reactive group, it does not have sufficient water repellency and cannot be expected to improve moisture resistance much. On the other hand, in the present invention, an alkoxymonosilane compound having an alkyl group, a phenyl group, or an alkyl-substituted phenyl group, which is a non-reactive water-repellent group, is mixed into the resin as the d component, so the silane coupling agent is Much higher moisture resistance can be obtained.

The epoxy resin as component a of this invention includes an epoxy compound having two or more epoxy groups in one molecule,
For example, from among bisphenol A type epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins, alicyclic epoxy resins, those having an epoxy equivalent of 2.20 or less and a softening point of 100°C or less are preferable. The one used is horse t C1 and other impurities removed as much as possible.

If the epoxy equivalent exceeds 220, the crosslinking density will be low and sufficient heat resistance and strength will not be obtained, and the softening point will be 10.
When the temperature is higher than 0°C, the flowability becomes poor and the moldability becomes poor.
These drawbacks result in a decrease in the moisture resistance of the semiconductor device.

The phenol novolak resin as component b of this invention acts as a curing agent for the epoxy resin 9 as component a. Other curing agents such as acid anhydrides and amine compounds are known, but such curing agents have poor moisture resistance and are unsuitable for the purpose of the present invention.

The above-mentioned phenol novolak resin is generally produced by mixing one or more of phenol, cresol, xylenol, nonylphenol, phenylphenol, bisphenol A, etc. with formaldehyde or paraformaldehyde using an acid, a base, or a neutral salt as a catalyst. Catalysts containing halogens such as hydrochloric acid are not preferred because the reaction product does not contain Cl 2 which has an adverse effect on semiconductor devices. Examples of catalysts that do not contain Ce include boric acid.

Furthermore, when the hydroxyl equivalent exceeds 150, the crosslinking density decreases, making it impossible to obtain sufficient heat resistance and strength, and when the softening point is higher than 120°C, flowability is required, resulting in poor moldability and semiconductor devices. has a negative impact on reliability.

The filler as component C of this invention reduces the linear expansion coefficient of the encapsulating material to prevent the phenomenon of peeling between the encapsulating resin and the element, lead frame, etc., and as a result improves the moisture resistance of the semiconductor device. It is for.

Examples of alkoxymonosilane compounds as component d of the invention include methyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, dimethyljethoxysilane, trimethylmethoxysilane, butyltrimethoxysilane, hexyltrimethoxysilane, and phenyltrimethoxysilane. Examples include silane, phenyltriethoxysilane, phenyldimethylethoxysilane, triphenylmethoxysilane, and nonylphenylmethoxysilane.

In this invention, the amounts of the above-mentioned components a to d are as follows:
10 to 25% by weight of component C and 5 to 25% by weight of component B in the entire composition
15% by weight, 65 to 85% by weight for C component, and 0.0% for D component.
The amount is preferably 0.02 to 1.0% by weight. this house,
In particular, if the amount of C component used is less than 65% by weight, the thermal shock resistance required for semiconductor devices will be greatly impaired, and if it exceeds 65% by weight, the moldability of the composition will deteriorate. Also, d
If the amount of the component used is less than 0.02% by weight, a sufficient effect of improving moisture resistance cannot be obtained, and on the other hand, if it is too large, the surface of the sealing resin will be stained and the marking property will be impaired. The optimum amount of component d to be used is 0.2 to 0.5% by weight.

In addition to the above a-yd components, the semiconductor-encapsulating epoxy resin composition of the present invention generally contains curing accelerators such as various amines, imidazoles, and phosphorus compounds, and mold release agents such as carnauba wax, montan wax, and stearic acid. agent is used. The amount of the curing accelerator and mold release agent used is approximately 0.1 to 1.0 weight of the entire composition. Also,
If necessary, known additives such as brominated epoxy resins, flame retardants, various inorganic flame retardants, pigments, modifiers, and the like may be blended.

Furthermore, as is known, it is preferable that the surface of the silica powder used be previously treated with a silane coupling agent.

In this invention, the various components described above are mixed using a Henschel mixer or the like, then kneaded or mixed by any method such as melt-kneading using heated rolls or an extruder, and then cooled and pulverized to produce the desired semiconductor encapsulation. The composition is used as an epoxy resin for use, but an excellent resin-sealed semiconductor device can be obtained by tabletting this composition in advance and then transfer molding it.

[Embodiments of the invention]

EXAMPLES Below, examples of the present invention will be described in more detail.

Examples Ortho-cresol novolac type epoxy resin (hereinafter referred to as epoxy resin-containing) having an epoxy equivalent weight of 196 and a softening point of 76°C, a flame-retardant epoxy resin having an epoxy equivalent weight of 270 (hereinafter referred to as epoxy resin B), and a phenol novolak having a phenol equivalent weight of 105. Resin, phosphorus-based curing accelerator (hereinafter referred to as curing accelerator), tertiary amine accelerator (hereinafter referred to as curing accelerator B), carnauba wax (mold release agent), antimony trioxide (flame retardant), silane Coupling agents, carbon black, silica powder, and silane compounds include methyltrimethoxysilane (silane A), butyltrimethoxysilane (silane B), phenyltrimethoxysilane (silane C), and phenyldimethylethoxysilane (silane D). Using this method, nine types of epoxy resin compositions for semiconductor encapsulation, including a comparative example, were obtained at the compounding ratios (wt%) shown in Table 1 below.

The above composition is prepared by first surface-treating the filler and flame retardant with a coupling agent, then adding the remaining ingredients and mixing with a Henschel mixer.
The mixture was kneaded with heated rolls, cooled, and then crushed. Elements for N/corrosion resistance testing were resin-sealed using each of the above compositions by a low-pressure transfer molding method, and the resulting resin-sealed semiconductor devices were subjected to a pressure vacuum test (
A test in water vapor at 2.5 atmospheres was conducted to evaluate the moisture resistance due to corrosion of the aluminum electrode. The result is the second
It was as shown in the table. In addition, the numerical value in the table is the number of defective pieces in which corrosion occurred out of 24 pieces tested.

Tables 2 and 3 show the results of evaluating the moisture resistance by applying a voltage of 18 V to the MOS IC device using a pressure gauge (2.0 atm). The number of tests is
There were 24 pieces, and Table 3 shows the number of defective pieces.

Table 3 [Effects of the Invention] As is clear from the above results, it can be seen that by using the epoxy resin composition of the present invention, a resin-encapsulated semiconductor device with good moisture resistance and high reliability can be obtained. .

Claims (1)

[Claims] (a) Epoxy equivalent is 220 or less and softening point is 100°C
10 to 25% by weight of the following epoxy resin; (b) 5 to 15% by weight of a novolac type phenolic resin with a hydroxyl equivalent of 150 or less and a softening point of 120°C or less; (c) 65 to 85% by weight of silica powder. (d) 0.02 to 1.0% by weight of an alkoxymonosilane compound having at least one alkyl group, phenyl group, or alkyl-substituted phenyl group.