JPH0721040B2 - Sealing resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a resin composition for encapsulation of electronic and electric parts and the like, which is excellent in moisture resistance and solder heat resistance.

(Prior Art) In recent years, in the field of semiconductor integrated circuits, along with technological development of high integration and high reliability, automation of a mounting process of a semiconductor device has been promoted. For example, when mounting a flat package type semiconductor device on a circuit board, conventionally, soldering was performed for each lead pin, but recently, the entire semiconductor device is dipped in a solder bath heated to 250 ° C or higher for soldering. The method of doing is adopted.

(Problems to be Solved by the Invention) In a semiconductor device sealed with a conventional resin composition composed of an epoxy resin, a novolac type phenolic resin, and an inorganic filler, moisture resistance decreases when the entire device is immersed in a solder bath. There was a drawback. In particular, when a semiconductor device that has absorbed moisture is dipped in solder, peeling occurs between the encapsulating resin and the semiconductor chip and frame, causing a significant deterioration in moisture resistance, causing wire breakage due to electrode corrosion and leak current due to moisture, and long-term reliability. It has the drawback that it cannot be guaranteed. Therefore, there has been a strong demand for the development of a sealing resin that is less affected by moisture absorption and has less moisture resistance deterioration even when the entire device is immersed in a solder bath.

The present invention has been made in order to solve the above-mentioned drawbacks and to meet the demand, and has a small influence of moisture absorption, and particularly provides a sealing resin composition having excellent moisture resistance and solder heat resistance after immersion in a solder bath. Is what you are trying to do.

[Structure of the Invention] (Means and Actions for Solving Problems) The present inventor has conducted diligent research to achieve the above-mentioned object, and as a result, if a ketone resin was added to the component of the sealing resin,
The inventors have found that the above object can be achieved by improving the moisture resistance and solder heat resistance, and completed the present invention.

That is, the present invention comprises (A) an epoxy resin, (B) a novolac type phenol resin, (C) a ketone resin, and (D) an inorganic filler as essential components, and with respect to the entire resin composition, (C) It contains 0.1 to 10% by weight of a ketone resin and 25 to 90% by weight of the (D) inorganic filler, and the (C) ketone resin does not include a cocondensation resin of a compound having a furan ring and a ketone. It is a resin composition for sealing characterized by the above. A sealing resin composition in which the equivalent ratio [(a) / (b)] of the epoxy group (a) of the epoxy resin and the phenolic hydroxyl group (b) of the novolac type phenol resin is within the range of 0.1 to 10 is there.

As the epoxy resin (A) used in the present invention, as long as it is a compound having at least two epoxy groups in its molecule, there are no particular restrictions on its molecular structure, molecular weight, etc., and those generally used for sealing materials can be used. Can be broadly included. Examples thereof include bisphenol type aromatic resins, alicyclic resins such as cyclohexane derivatives, and epoxy novolac resins represented by the following general formula.

(In the formula, R ¹ represents a hydrogen atom, a halogen atom or an alkyl group, R ² represents a hydrogen atom or an alkyl group, and n represents an integer of 1 or more.) These epoxy resins may be used alone or in combination of two or more. Used as a system.

Examples of the (B) novolak type phenol resin used in the present invention include novolak type phenol resins obtained by reacting phenols such as phenol and alkylphenol with formaldehyde or paraformaldehyde, and modified resins thereof, for example, epoxidized or butylated novolak. Examples thereof include phenolic resins and the like, and these resins are used alone or as a mixed system of two or more kinds. The mixing ratio of the novolac type phenol resin is the equivalent ratio [(a) / (b) of the epoxy group (a) of the above-mentioned (A) epoxy resin and the phenolic hydroxyl group (b) of (B) the novolac type phenol resin). ] Is preferably within the range of 0.1 to 10. If the equivalent ratio is less than 0.1 or exceeds 10, the moisture resistance, the molding workability, and the electrical properties of the cured product deteriorate, which is not preferable. Therefore, it is preferable to limit it to the above range.

The (C) ketone resin used in the present invention is not particularly limited in molecular weight, molecular structure and the like and can be widely used as long as it is obtained by a polycondensation reaction of a ketone and formaldehyde in the presence of an alkali catalyst. However, the (C) ketone resin does not include a co-condensation resin of a compound having a furan ring and a ketone, for example, a furfural-ketone co-condensation resin. Specific examples include the following.

(However, in the formula, n represents an integer of 1 or more.) These ketone resins are used alone or as a mixed system of two or more kinds. The blending ratio of the ketone resin is in the range of 0.1 to 10% by weight based on the entire resin composition. If the proportion is less than 0.1% by weight, it has no effect on solder heat resistance.
If it exceeds 5% by weight, it has an adverse effect on moldability such as mold fouling and viscosity increase, and is not suitable for practical use. By using this ketone resin, the adhesiveness between the encapsulating resin and the semiconductor chip and the adhesiveness between the encapsulating resin and the lead frame are improved, and the moisture resistance is less deteriorated even when immersed in a solder bath.

Examples of the inorganic filler (D) used in the present invention include silica powder, alumina, antimony trioxide, talc, calcium carbonate, titanium white, clay, mica, red iron oxide, glass fiber, carbon fiber and the like, which may be used alone or Used as a mixed system of two or more kinds. Of these, silica powder and alumina are particularly preferably used. The blending ratio of the inorganic filler is 25 to 90 with respect to the entire resin composition.
It is contained in the range of% by weight. If the proportion is less than 25% by weight, the moisture resistance, heat resistance, mechanical properties and moldability are not effective, and if it exceeds 90% by weight, the dryness becomes large and the moldability becomes poor and it is not suitable for practical use.

The encapsulating resin composition of the present invention contains an epoxy resin, a novolac-type phenol resin, a ketone resin, and an inorganic filler as essential components, but if necessary, natural waxes, synthetic waxes, and straight chain fatty acid metals. Mold release agents such as salts, acid amides, esters, paraffins, chlorinated paraffins,
Flame retardants such as bromotoluene, hexabromobenzene and antimony trioxide, colorants such as carbon black and red iron oxide, silane coupling agents, various curing accelerators and the like may be appropriately added and blended.

A general method for producing the encapsulating resin composition of the present invention as a molding material is to select an epoxy resin, a novolac type phenolic resin, a ketone resin, an inorganic filler, and other raw material components at a predetermined composition ratio. , After mixing sufficiently evenly with a mixer or the like, further melt mixing treatment with a hot roll,
Alternatively, it is mixed with a kneader or the like, cooled and solidified, and then crushed to an appropriate size to obtain a molding material. The molding material thus obtained can be applied to sealing, covering, insulating, etc. of electronic parts or electric parts.

(Examples) Next, the present invention will be specifically described by way of examples, but the present invention is not limited to the following examples. In the following Examples and Comparative Examples, "%" means "% by weight".

Example 1 Cresol novolac epoxy resin (epoxy equivalent 21
5) 18%, novolac type phenol resin (phenol equivalent 107) 9%, ketone resin 2% represented by the following formula, 71% fused silica powder, 0.3% hardening accelerator, 0.3% ester wax, and 0.4% silane coupling agent are mixed at room temperature, then kneaded at 90 to 95 ° C, cooled, and then ground to form a molding material. Got The obtained molding material was transferred into a mold heated to 170 ° C. and cured to obtain a molded product (sealed product). Various properties relating to moisture resistance, stress, etc. were tested on this molded product, and the results are shown in Table 1. The remarkable effects of the present invention were recognized.

Example 2 Cresol novolac epoxy resin (epoxy equivalent 21
5) 18%, novolac type phenol resin (phenol equivalent 107) 9%, ketone resin 2% represented by the following formula, Example 1 containing 71% silica powder, 0.3% curing accelerator, 0.3% ester wax and 0.4% silane coupling agent.
Mixing, kneading and crushing were carried out in the same manner as above to obtain a molding material. Then, a molded product was obtained in the same manner as in Example 1, and various properties related to moisture resistance, stress, etc. were tested. The results are shown in Table 1. The remarkable effect of the present invention was recognized.

Comparative Example Cresol novolac epoxy resin (epoxy equivalent 21
5) 19%, novolac type phenol resin (phenol equivalent 107) 9%, silica powder 71%, curing accelerator 0.3%, ester wax 0.3% and silane coupling agent
0.4% was obtained in the same manner as in Example 1 to obtain a molding material. Using this molding material, a molded product was made, and various characteristics of the molded product were tested in the same manner as in Example 1. The results are shown in Table 1.

The tests of water absorption, glass transition temperature, and moisture resistance after immersion in a solder bath, which were carried out for Examples and Comparative Examples, were conducted as follows. The water absorption rate is 50 by the transfer molding.
A molded product having a thickness of 3 mm and a thickness of 3 mm was prepared, and the molded product was allowed to stand in saturated steam at 127 ° C. and 2.5 atmospheric pressure for 24 hours, and the weight was increased. The glass transition temperature was measured by using a thermomechanical analyzer by making a molded article similar to that used in the water absorption test and subjecting this to post-curing at 175 ° C. for 8 hours to prepare a test piece of an appropriate size. Further, the humidity resistance is measured by using the resin composition for sealing.
Bond a silicon chip (test element) with two or more aluminum wires to a normal 42 alloy frame,
Tunspher molding was carried out at 175 ° C. for 2 minutes to obtain a 5 × 10 × 1.5 mm flat package type molded product, which was then post-cured at 175 ° C. for 8 hours. Pre-mold this molded product at 40 ℃, 90% RH, 100
After moisture absorption for a period of time, it was immersed in a solder bath at 250 ° C. for 10 seconds. After that, a pressure cooker test (PCT) was performed in saturated steam at 127 ° C. and 2.5 atm, and the breakage due to the corrosion of aluminum was evaluated as defective.

[Effects of the Invention] As is clear from the above description and Table 1, the encapsulating resin composition of the present invention has good adhesiveness to semiconductor chips and lift-off, and therefore has little effect of moisture absorption and is suitable for solder baths. Even after the immersion, the moisture resistance is excellent, and as a result, it is possible to remarkably reduce the disconnection due to the corrosion of the electrodes and the generation of the leakage current due to the moisture, and the reliability can be guaranteed for a long time. It also showed excellent heat resistance despite immersion in a solder bath at 250 ° C or higher.

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Claims (2)

[Claims] 1. An epoxy resin (A), a novolac type phenol resin (B), a ketone resin (C) and an inorganic filler (D) as essential components, and the (C) ketone is added to the entire resin composition. 0.1 to 10% by weight of a resin, 25 to 90% by weight of the (D) inorganic filler, and (C) a ketone resin not containing a cocondensation resin of a compound having a furan ring and a ketone. A resin composition for encapsulation, comprising: 2. The equivalent ratio [(a) / (b)] of the epoxy group (a) of the epoxy resin and the phenolic hydroxyl group (b) of the novolac type phenol resin is in the range of 0.1 to 10. The encapsulating resin composition according to claim 1.