JPH075823B2 - Resin composition for semiconductor encapsulation - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a resin that protects the surface of a semiconductor, and more specifically, a semiconductor element on a ceramic substrate is sealed with a resin, and aluminum wiring on the element surface is used. Relates to a liquid resin composition for semiconductor encapsulation, which is intended to prevent corrosion caused by invasion of moisture from the outside.

(Prior Art) Liquid resins for sealing semiconductor elements can be classified into organic substrates and ceramic substrates depending on the type of substrate on which the semiconductor element is mounted.

Both types require reliability characteristics such as heat resistance, moisture resistance, and thermal shock resistance, but especially for ceramic substrates, the thermal expansion coefficient of the substrate is usually as small as 7 × 10 ^-6 / ° C, and for sealing It is necessary to reduce the thermal stress caused by the difference in thermal expansion coefficient between the resin and the substrate.

When the thermal stress increases, the resin cured product may crack or the resin cured product may peel off from the substrate, resulting in a significant decrease in the reliability of the semiconductor element.

Therefore, in order to reduce the thermal stress, a silicone resin with a low elastic modulus is used.However, the adhesiveness is weak, the moisture absorption is high, and the hardened material is soft, so the internal gold when the force is applied from the outside. There are drawbacks such as broken wires, and there is a problem in terms of reliability.

On the other hand, epoxy resin can be mentioned as a resin that has good adhesion, moisture absorption, and hardness of the cured product and is also excellent in reliability, but its large elastic modulus causes large thermal stress and cannot be used as a resin for ceramic substrates. .

Therefore, it has been considered to add an inorganic filler to the epoxy resin to reduce the coefficient of thermal expansion, but the viscosity of the liquid resin increases with an increase in the amount of the filler added, resulting in the drawback of extremely poor workability. .

(Object of the Invention) The present invention improves the drawbacks of conventional liquid resins,
A liquid resin composition for semiconductor encapsulation having excellent reliability characteristics and workability is provided.

As a result of diligent studies by the present inventors, in the liquid resin consisting of an epoxy resin and an inorganic filler, the addition amount and particle size distribution of the inorganic filler, by controlling the addition amount of the organic solvent, thermal stress characteristics, reliability characteristics It was found that the workability was excellent and the workability could be improved to a high degree, and based on this knowledge, various studies were carried out to find an appropriate compounding ratio, and this object was achieved.

(Structure of the Invention) The present invention includes (A) epoxy resin, (B) epoxy resin curing agent, and (C) particle size distribution in which the number of particles having a particle size of 10 μm or less is 25
% Or less and the number of particles having a particle size of 50 μm or more is 15 to 50%, and a liquid resin composition for semiconductor encapsulation comprising (D) an organic solvent, the composition ratio of which is (C) / (A) + Liquid resin for semiconductor encapsulation in which (B) + (C) = 50 to 80% by volume and (D) / (A) + (B) + (C) + (D) = 20 to 40% by volume It is a composition.

(Function) The epoxy resin used in the present invention may be an ordinary epoxy resin, but as the content of hydrolyzable halogen groups,
It is desirable that the content is 500 ppm or less. Moreover, the following types are mentioned as the type. Phloroglucinol triglycidyl ether, trihydrooxybiphenyl triglycidyl ether, tetrahydroxybiphenyl tetraglycidyl ether, tetrahydroxybisphenol F tetraglycidyl ether, tetrahydroxybenzophenone tetraglycidyl ether, epoxidized novolak, epoxidation Polyvinylphenol, triglycidyl isocyanurate, triglycidyl cyanurate, triglycidyl S-triazine, triglycidyl aminophenol, tetraglycidyl diaminodiphenylmethane, tetraglycidyl pyromellitic acid, triglycidyl trimellitic acid, diglycidyl Resorcin, diglycidyl bisphenol A, diglycidyl bisphenol S, dihydride Diglycidyl Zeal ether carboxymethyl benzophenone, diglycidyl Ziehl-oxybenzoate, diglycidyl Ziehl phthalate (o, m,
p), diglycidyl hydintyne, diglycidyl aniline, diglycidyl toluidine, etc., and these can be used alone or in combination of two or more kinds.

A low-viscosity epoxy resin generally called a reactive diluent may be used in combination with the above epoxy resin. For example, cycloaliphatic epoxy compounds of vinyl cyclohexene oxide, polyolefin epoxides such as diglycidyl phenyl glycidyl ether and divinylbenzene epoxy, glycidyl amines such as diglycidyl aniline and diglycidyl toluidine, butyl glycidyl ether,
Examples thereof include glycidyl ethers such as phenyl glycidyl ether and cresyl glycidyl ether, and other glycidyl esters.

The curing agent used in the present invention may be an ordinary one, and includes polyhydric phenols, aromatic polybasic acids, aromatic polyamines and the like.

As the polyhydric phenols, an amorphous resinous substance which is an initial condensation product of phenols and aldehydes and contains free phenol as little as possible is preferable. For example, a low molecular weight liquid novolak mainly composed of dinuclear and trinuclear bodies obtained by reacting monohydric phenols such as phenol, cresol and xylenol with formaldehyde in dilute aqueous solution under strong acidity and monohydric phenols Examples thereof include initial condensates under acidic conditions with polyfunctional aldehydes such as acrolein and glyoxal, and initial condensates under acidic conditions with polyhydric phenols such as resorcin, catechol and hydroquinone and formaldehyde.

Examples of the aromatic polybasic acid include polybasic acids such as pyromellitic anhydride and trimellitic anhydride, and polybasic acid derivatives obtained by linking a few molecules of the polybasic acid with a difunctional trifunctional polyol through an ester bond. , Maleic anhydride, phthalic anhydride,
Examples thereof include a eutectic mixture of a bifunctional acid anhydride such as endomethylenetetrahydrophthalic anhydride and hexahydrophthalic anhydride with the above polybasic acid.

Two or more kinds of these curing agents may be used in combination, if necessary.

Examples of the inorganic filler used in the present invention include silica, alumina, calcium carbonate, magnesium oxide, magnesium hydroxide, boron nitride and the like.
It is possible to use a combination of two or more species.

The particle size distribution of these inorganic fillers is as follows:
It is necessary that the number of particles of 25% or less and 50 μm or more is 15 to 50%. By using the inorganic filler having such a particle size distribution, a large amount of the inorganic filler is blended, and the thermal expansion coefficient of the cured product is increased. The workability of the liquid resin could be kept good while making it small.

In the particle size distribution of the inorganic filler, the number of particles of 10 μm or less is 25
When the content is more than 100%, the specific surface area of the inorganic filler becomes large, the viscosity increases, and the workability deteriorates remarkably. Further, even if the number of particles having a particle size of 50 μm or more is 15% or less, the specific surface area increases, the viscosity increases, and the workability deteriorates. On the other hand, the number of particles of 50 μm or more
When the content is more than 0.1%, the inorganic filler is easily separated from the epoxy resin, the curing agent and the solvent, sedimentation of the inorganic filler occurs, the workability is deteriorated, and a uniform cured product cannot be obtained and reliability is lowered.

In order to reduce the coefficient of thermal expansion of the cured product of the liquid resin, the compounding amount of the inorganic filler may be increased. At this time, the factor that determines the coefficient of thermal expansion is the volume ratio of the resin component of the cured product to the inorganic filler, and it is necessary to control it by an appropriate volume ratio.

When the weight ratio is controlled, the specific gravity varies depending on the type of the inorganic filler, and even if the weight ratio is the same, the volume ratio and the coefficient of thermal expansion also differ depending on the respective inorganic fillers.

Further, as an appropriate range of the volume ratio of the inorganic filler and the resin component, it is possible to keep the thermal expansion coefficient of the cured product as close as possible to the thermal expansion coefficient of the ceramic substrate, and prevent the increase in the viscosity of the liquid resin and maintain good workability. This is an important point.

It is essential that the compounding ratio of these inorganic fillers is (inorganic filler) / (epoxy resin) + (epoxy resin curing agent) + (inorganic filler) = 50 to 80% by volume.

By blending in a ratio within this range, the workability of the liquid resin is very good, and the thermal expansion coefficient of the cured product is also small, the thermal stress is small, and the occurrence of cracks and peeling from the ceramic substrate occurs. Can be prevented.

When the compounding ratio of the inorganic filler is 50% by volume or less, the amount of the inorganic filler in the cured resin is small and the coefficient of thermal expansion is large, and as a result, thermal stress is large and cracking or separation from the ceramic substrate occurs. Occurs, and the reliability of the semiconductor is significantly reduced. On the other hand, if the blending ratio is 80% by volume or more, the amount of the inorganic filler in the liquid resin becomes too large and the viscosity becomes high, resulting in poor workability.

The organic solvent used in the present invention may be a conventional one, such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methanol, ethanol, isopropanol, butanol, isobutanol, methyl cellosolve, ethyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, butyl cellosolve acetate. State, methyl carbitol, ethyl carbitol, butyl carbitol, hexane, benzene, toluene, xylene and the like. The compounding amount of the organic solvent used here is (organic solvent) / (epoxy resin) + (epoxy resin curing agent) +
It is essential that (inorganic filler) + (organic solvent) = 20-40% by volume.

If it is 20% by volume or less, the viscosity of the liquid resin becomes too high, and the workability is significantly deteriorated. If it is 40% by volume or more, the inorganic filler and the epoxy resin, the curing agent, and the solvent are easily separated,
Sedimentation of the inorganic filler deteriorates workability, and a uniform cured product cannot be obtained, resulting in poor reliability.

The liquid resin composition of the present invention may contain a curing accelerator, a defoaming agent, a dispersion stabilizer, a flame retardant and a colorant, if necessary.

(Example) Example 1 Phenolic nopolak epoxy resin having a hydrolyzable chlorine content of 360 ppm (number average molecular weight 340, epoxy equivalent 180) 10% by volume phenol novolac (number average molecular weight 310, OH equivalent 105)
5〃 20% of particles with particle size 10μm or less, 3 with particles of 50μm or more
0% of silica 50 〃 ethyl cellosolve 35 〃 was kneaded with a raikai machine to obtain a homogeneous liquid resin composition.

The obtained liquid resin composition had good workability, and when the semiconductor element on the ceramic substrate was sealed, the resin cured product did not crack or peel.

Also, using a simulated element, preheat at 80 ° C for 2 hours, then perform main curing at 150 ° C for 3 hours and seal, and then perform a temperature cycle test (TC).
After 100 cycles and 100 hours of pressure cooker test, there was no aluminum corrosion in the circuit and no defects due to wear of the gold wire, and it had excellent reliability.

The results are shown in Table 1.

Example 2 13% by volume of bisphenol A epoxy (number average molecular weight of 380, epoxy equivalent of 190) of 400 ppm of hydrolyzable chlorine as an epoxy resin, 4% by volume of monoethyldiaminodiphenylmethane as a curing agent, and a particle size of 10 μm or less as an inorganic filler. 5% calcium carbonate with a particle number of 15% and a particle number of 50 μm or more of 20%
3% by volume, 30% by volume of methyl ethyl ketone as an organic solvent
Was mixed in the same manner as in Example 1 to obtain a liquid resin.

The obtained product was good in workability, cured product appearance and reliability in the same manner as in Example 1.

The results are shown in Table 1.

Comparative Examples 1 to 5 Liquid resins were prepared with the formulations shown in Table 1 in the same manner as in Example 1, but all had poor viscosity and poor workability.

Further, in Comparative Example 4, the appearance of the cured product was poor because the amount of the inorganic filler was small.

The results are shown in Table 1.

Comparative Examples 6 and 7 Liquid resins were prepared with the formulations shown in Table 1 in the same manner as in Example 2, but all had poor viscosity and poor workability.

The results are shown in Table 1.

(Effect of the invention) The cured product using the liquid resin composition for semiconductor encapsulation according to the present invention has a small thermal expansion coefficient, and therefore can prevent an increase in viscosity of the liquid resin when an inorganic filler is blended. ,
Workability is extremely good. Moreover, since the thermal stress can be reduced, cracks and peeling do not occur when the semiconductor element is sealed.

This makes it possible to take advantage of the excellent adhesiveness, moisture absorption rate, and hardness of the cured product of epoxy resin, and the moisture resistance and heat resistance required as a liquid resin for sealing semiconductor elements mounted on a ceramic substrate. It is a liquid resin composition for semiconductor encapsulation that can respond to reliability characteristics such as impact resistance.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-54-141569 (JP, A) JP-A-55-29532 (JP, A) JP-A-61-255927 (JP, A) JP-A-63- 186725 (JP, A) JP 63-245430 (JP, A) JP 60-106824 (JP, A) JP 58-187426 (JP, A) JP 63-132924 (JP, A)

Claims (1)

[Claims] (A) Epoxy resin (B) Epoxy resin curing agent (C) Inorganic filler in which the number of particles having a particle size of 10 μm or less is 25% or less and the number of particles having a particle size of 50 μm or more is 15 to 50% (C) D) A liquid resin composition for semiconductor encapsulation comprising an organic solvent, the composition ratio of which is (C) / (A) + (B) + (C) = 50-80% by volume, and (D) / (A) + (B) + (C) + (D) = 20-40 volume%, The resin composition for semiconductor sealing characterized by the above-mentioned.