JPH02212541A - Liquid resin composition for semiconductor sealing - Google Patents

Abstract

PURPOSE:To obtain the title composition which has a low water absorptivity and excellent adhesiveness to the surface of a semiconductor element and can prevent the aluminum wiring on the surface of an element from being corroded by the moisture infiltrating from outside by adding an aminosilane compound to a specified fluororesin. CONSTITUTION:A liquid resin composition is produced by mixing a vinylidene fluoride/hexafluoropropylene copolymer (A) of the formula (wherein m/n is 1-20) with an aminosilane compound (B) (e.g. aminopropyltriethoxysilane), an inorganic filler (C) (e.g. silica) and an organic solvent (D). The above mixing is performed so that the ratio of component C to components A, B and C may be 30-80wt.%. This composition is useful for the production of a resin film for protecting the surface of a semiconductor element, has a very low water absorptivity and excellent adhesiveness to the surface of a semiconductor element and can prevent the aluminum wiring on the surface of an element from being corroded by the moisture infiltrating from the outside.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a resin that protects the surface of a semiconductor element, and more specifically, a resin that has extremely low water absorption and excellent adhesion to the surface of a semiconductor element. , relates to a liquid resin composition for semiconductor encapsulation whose purpose is to prevent corrosion of aluminum wiring on the surface of a device caused by moisture intrusion from the outside.

(Prior Art) There are two main methods for encapsulating semiconductor elements. One is to transfer mold the element bonded onto a metal lead frame using a solid resin composition. The other method is to bond a bare element directly onto a printed wiring board and seal it with a liquid resin composition by a dropping method.

In the transfer molding method, the molded product is mounted on a printed wiring board, which inevitably results in a thick and large product.

In recent years, there has been a demand for electronic devices to be lighter, thinner, and smaller, and for this reason, a method of sealing by a dropping method using a liquid resin composition has been attracting attention.

Conventionally, epoxy resins have been widely used for such dropping method applications.

In order to make epoxy resins easier to use in the dropping method, a curing agent with a lower viscosity is used, and for example, a liquid acid anhydride such as methyltetrahydrophthalic anhydride is often used.

However, when such acid anhydride is used as a curing agent, the cured product contains many ester bonds that are easily hydrolyzed in the cured structure, resulting in poor moisture resistance.Especially in the PCT test required for semiconductor encapsulation resin, the cured product has poor moisture resistance. It is easy for water to enter through the resin or from the interface between the resin and the substrate <10
There was a problem in that the aluminum wiring of the semiconductor element corroded in a matter of hours.

(Problems to be Solved by the Invention) It is an object of the present invention to improve the drawbacks of conventional liquid resin compositions for semiconductor encapsulation, and to improve the ability of the liquid resin composition to hardly deteriorate in the PTC test even though it is a liquid resin produced by the dropping method. First, it is an object of the present invention to provide a liquid resin composition for semiconductor encapsulation that has excellent moisture resistance.

(Means for Solving the Problems) The present invention uses a copolymer (A) of vinylidene fluoride and propylene hexafluoride, which has a low saturated water absorption rate and has a specific copolymerization ratio m/n represented by the following formula CI. It is a liquid resin composition containing as essential components aminosilane (B) to improve adhesion, and a specific number of blended inorganic fillers (C) and organic solvents (D) to provide workability as a liquid resin. hand,(
The copolymerization ratio m/n of A) is 1 to 20, particularly 5 to 15
It is desirable that the mixture ratio of (C) be within the range of (C)
/ (A) + (B) + (C) is 30~80M
This is a liquid resin composition for semiconductor encapsulation, characterized in that the amount is %.

(Function) A feature of the liquid resin composition of the present invention is that the water absorption rate of the cured product is extremely low.
In tests, it is easily susceptible to hydrolysis, has a high water absorption rate, and has very low moisture resistance.

In addition, even with ordinary epoxy resin transfer molding materials, the saturated water absorption rate in the PCT test is about 0.7%, which means that even if it is assumed that the inorganic filler does not absorb water at all, the epoxy resin as a binder absorbs about 2% of water. This is to do so.

The copolymer of vinylidene fluoride and propylene 677 used in the present invention has a very low saturated water absorption rate in the PCT test, which is 0.05% or less.

However, in the copolymer represented by formula [I], if the copolymerization ratio m/n is greater than 20, the fluorine content will be low and the water absorption will be high. If m/n is smaller than 1, the water absorption rate will be low but the moisture permeability will be high.

In addition, fluororesins generally have strong non-adhesiveness with other substances, and cannot be used as they are because they have poor adhesion with semiconductor elements for the purpose of the present invention, and the resin itself has a low water absorption rate. However, moisture intrudes from the interface between the semiconductor element surface and the resin, causing problems such as corrosion of the aluminum wiring.

In order to improve this drawback, the present inventors have conducted extensive studies on various cambling agents, and have found that when an aminosilane compound is added to the fluororesin used in the present invention, adhesion is significantly improved, which was previously unimaginable. The present invention has been found to be improved and the object of the present invention has been achieved.

The aminosilane compound used in the present invention is a compound having both an amino group and a silanol group, or an amino group and an lanol group derivative, such as amineethylsilanol, aminoethyltrimethoxysilane, aminoethyltriethoxysilane, aminopropyl Examples include silanoltrimethoxysilane, aminobrobyltriethoxysilane, γ-(2-ureidoethyl)aminopropyltrimethoxysilane, and γ-ureidopropyltriethoxysilane.

Furthermore, as an essential component of the present invention, there is an inorganic filler and an organic solvent, but the intended use of the present invention requires a liquid state, and the inorganic filler is added to the liquid resin composition of the present invention with an appropriate viscosity. , imparts chicken properties and makes the liquid resin composition excellent in workability, while at the same time reducing the coefficient of thermal expansion of the cured product, reducing thermal stress, preventing cracks in the cured product, and sealing with semiconductor elements during use. The purpose of this is to prevent the serious defect that the gold wire connecting the element surface and the external lead breaks due to the difference in thermal tension of the resin used.

Therefore, the blending ratio of inorganic filler is 30 to 80% by weight.
is appropriate; if it is less than 30% by weight, the coefficient of thermal expansion will increase and workability will deteriorate. Moreover, if the amount exceeds 801i, it is not possible to impart appropriate viscosity and consistency, and in order to achieve these properties, it is necessary to add a large amount of organic solvent, and as a result, the resin content decreases. As a result, voids are likely to occur in the cured product, resulting in increased water absorption.

Inorganic fillers used in the present invention include silica, alumina, calcium carbonate, magnesium oxide, magnesium hydroxide, boron nitride, zinc oxide, etc., and these can be used alone or in combination of two or more.

Liquid sealing resin compositions are often used by filling them into a syringe and dropping them with a dispenser. Therefore, the particle size of the inorganic filler used must be smaller than the inner diameter of the needle at the tip of the syringe. , the maximum particle size is preferably 200 μm or less.

Further, as the organic solvent used in the present invention, any organic solvent can be used as long as it can dissolve the copolymer of vinylidene fluoride and propylene hexafluoride, but in particular, ketone-based solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone can be used. Solvents, polar solvents such as dimethyl 7-olamide methyl-2-pyrrolidone, or combination systems thereof are excellent.

In addition, in the heat curing of the liquid resin composition of the present invention, it is necessary to perform the curing at a low temperature when a low boiling point solvent is used, and at a high temperature when a high boiling point solvent is used. In order to reduce the
C/60 minutes→150-200°C/60 minutes is preferable.

In the present invention, there is no problem in adding an antifoaming agent, a dispersion stabilizer, a coloring agent, etc., if necessary.

(Example) Example 1 A copolymer of vinylidene heptadide and propylene hexafluoride represented by the formula below with a copolymerization ratio of m/n-10 was dissolved in dimethylacetamide to a concentration of 20% by weight. Ta.

A coupling agent and silica (average particle size 20 μm, maximum particle size 150 μm) are blended into this solution at the mixing ratio shown in Table 1, and kneaded with three rolls to form a homogeneous liquid sealing resin composition. Obtained.

This resin composition was applied onto a silicone wafer using a spinner and cured at 100°C/60 minutes → 200°C/60 minutes under PCT test conditions (125°C).

The adhesiveness with the silicone wafer was examined. In the same process, this resin composition was cast onto aluminum foil and cured, and then the aluminum foil was removed by etching to create a film with a thickness of 100 μm.The water absorption rate and moisture permeability (J
IS-Z-0208) was measured.

Furthermore, this resin composition was drop-sealed on the surface of the simulated element using a dispenser, cured under the above conditions, and then subjected to a thermal shock test in a cycle of -55°C←→125°C (processing time 30 minutes). The presence or absence of gold wire breakage after 100 cycles was investigated. Also, using this sealed simulated element, PCT
The treatment was carried out under test conditions (125"C!, 2.3 atm) and the time required for aluminum corrosion to occur was investigated.

The simulated element used was a chip in which aluminum was vapor-deposited in a comb-shaped pattern with a line spacing/width of 5 μm on a 5 mm square silicone wafer, which was bonded to a printed wiring board (glass cloth/epoxy resin) with silver paste and a 25 μm gold wire. It was pounded.

The above test results are shown in Table 1.

Examples 2 to 3, Comparative Examples 1 to 4 Similarly to Example 1, liquid resin compositions were prepared using the formulations shown in Table 1, and similar tests were conducted. Table 1 shows the results.

Comparative Example 5 As shown in Table 1, the amount of inorganic filler (silica) was 8
A liquid resin composition was prepared with a concentration of 2% by weight.

The obtained product had very poor spreadability in drop coating, and an attempt was made to create a test piece by adding dimethylacetamide to lower the viscosity, but a large number of voids occurred during curing, making it difficult to test. The piece could not be made properly and could not be tested.

Comparative Example 6 Bisphenol A type epoxy resin (epoxy fi 190) obtained by the reaction of bisphenol A and epichlorohydrin and methyltetrahydrophthalic anhydride,
A coupling agent and silica are blended as shown in Table 1,
Further, 1 part by weight of l.lis-dimethylamino-methylphenol was added as a curing accelerator to 100 parts by weight of the epoxy resin, a liquid sealing resin composition was obtained in exactly the same manner as in Example 1, and a test piece was prepared. The test was conducted in the same manner as in Example 1, and the results are shown in Table 1.

(Effects of the Invention) The liquid resin composition for semiconductor encapsulation obtained by the present invention has a very low water absorption rate and has excellent adhesion to Silicon Ueno 1, compared to the conventional liquid resin composition for semiconductor encapsulation. A cured product with high reliability in the PCT test, which could never be obtained with a physical product, can be obtained, and is extremely suitable for semiconductor encapsulation.

Claims (1)

[Claims] (1) (A) Copolymer of vinylidene fluoride and propylene hexafluoride represented by the following formula [I]▲There are mathematical formulas, chemical formulas, tables, etc.▼……[I] (B) Aminosilane (C) Inorganic filling (D) A liquid resin composition comprising an organic solvent, the copolymerization ratio of (A) m
/n is 1 to 20, and the blending ratio of (C) (C)/
A liquid resin composition for semiconductor encapsulation, characterized in that (A)+(B)+(C) is 30 to 80% by weight.