JPH0216148A - Sealing resin composition - Google Patents

Abstract

PURPOSE:To form a sealing resin composition less affected by absorbed water, being excellent in, especially, humidity resistance after being immersed in a soldering bath and soldering-heat resistance and having high reliability by mixing a specified novolac epoxy resin with a novolac phenol resin and a silica powder. CONSTITUTION:This sealing composition essentially consists of a novolac epoxy resin having an alkyl-modified polyphenol resin as a skeleton, obtained by reacting an alkyl-modified hydroxybenzaldehyde with an alkyl-modified phenol (wherein the alkyl group of said hydroxybenzaldehyde is CmH2m+1, m is an integer >=1, and the alkyl group of the alkyl-modified phenol is CnH2n+1, and n is an integer in the range of 10>=n>=1), a novolac phenol resin, and 50-90wt.%, based on the total resin composition, silica powder.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a resin composition for sealing electronic components, etc., which has good moisture resistance and soldering heat resistance.

(Prior Art) In recent years, in the field of semiconductor integrated circuits, along with technological developments for higher integration and higher reliability, automation of semiconductor device mounting processes has been promoted. For example, when attaching a flat package type semiconductor device to a circuit board, conventionally each lead pin was soldered, but recently a solder dip method or a flow one method has been adopted.

(Problems to be Solved by the Invention) Semiconductor devices encapsulated with conventional resin compositions made of epoxy resin, novolac type phenolic resin, and silica powder have the disadvantage that moisture resistance decreases when the entire device is immersed in a solder bath. was there. In particular, when semiconductor devices that have absorbed moisture are immersed in solder, peeling and internal resin cracks occur between the sealing resin and the semiconductor chip and lead frame, resulting in significant moisture resistance deterioration, disconnection due to electrode corrosion, and leakage current due to moisture. However, it has the disadvantage that long-term reliability cannot be guaranteed. Therefore, there has been a strong demand for the development of a sealing resin composition that is less affected by moisture absorption and exhibits less deterioration in moisture resistance even when the entire semiconductor device is immersed in a solder bath.

The present invention was made in response to the above-mentioned demands.
The present invention aims to solve the above-mentioned drawbacks and provide a highly reliable sealing resin composition that is less affected by moisture absorption, particularly has excellent moisture resistance after immersion in a solder bath and soldering heat resistance.

[Structure of the Invention] (Means for Solving the Problems) As a result of intensive research aimed at achieving the above object, the present invention uses a novolac-type epoxy resin having an alkyl-modified polyfunctional phenolic resin skeleton. The present invention was completed based on the discovery that the above objects can be achieved with excellent moisture resistance and soldering heat resistance. That is,
The present invention is directed to (A) a novolac type epoxy resin having a backbone of an alkyl-modified polyfunctional phenol resin obtained by reacting an alkyl-modified hydroxybenzaldehyde and an alkyl-modified phenol (provided that the alkyl group of the alkyl-modified hydroxybenzaldehyde is Cq H2II++, and the monk is m≧
represents an integer of 1, and the alkyl group of the alkyl-modified phenol is CnH2o, where n is 10≧n≧1
(represents an integer of ) (B) novolac type phenol resin and (C) silica powder are essential components, and the above (C) is added to the entire resin composition.
This is a sealing resin composition characterized by containing 50 to 90% by weight of silica powder.

As long as the novolac type epoxy resin (A) having a skeleton of an alkyl-modified polyfunctional phenol resin used in the present invention has a skeleton structure of the above-mentioned specific aldehyde and specific phenol in its molecule, there are no particular restrictions on its molecular structure, molecular weight, etc. It is widely covered without being restricted. Specifically, for example, in addition to a novolak-type epoxy resin having a nol resin as its backbone, a novolak-type epoxy resin represented by the following general formula can be mixed and used.

These can be used alone or in combination. The alkyl-modified polyfunctional compound of (A) above (wherein, R1 is a hydrogen atom, a halogen atom, or an alkyl group,
(2 represents a hydrogen atom or an alkyl group, and n represents an integer of 1 or more) The novolac type phenol resin (B) used in the present invention is a resin obtained by reacting phenols such as phenol and alkylphenol with formaldehyde or paraformaldehyde. Examples include the obtained novolak type phenolic resin and modified resins thereof, such as epoxidized or butylated novolak type phenolic resin, and the novolak can be widely used without any particular restriction as long as it is a phenolic resin. These novolac type phenolic resins can be used either individually or in combination of two or more.

As the silica powder (C) used in the present invention, commercially available ones are generally used, but among them, those with a low impurity concentration and an average particle size of 30 μm or less are preferable. If it exceeds 30 μm, it is unfavorable for moisture resistance and moldability. The blending ratio of silica powder is preferably 50 to 90% by weight based on the resin composition.

If the blending ratio is less than 50% by weight, the moisture absorption of the resin composition is high and the moisture resistance after solder immersion is poor, which is not preferable. On the other hand, if it exceeds 90% by weight, fluidity becomes extremely poor and moldability becomes poor, which is not preferable. Therefore, it is limited within the above range.

The sealing resin composition of the present invention is made of epoxy-type epoxy (・>1
The essential ingredients are fat, novolac type phenolic resin, and silica powder, but if necessary, natural waxes, synthetic waxes, metal salts of straight chain fatty acids, acid amides,
Add esters, flying agents such as paraffin, flame retardants such as antimony trioxide, colorants such as carbon black, silane coupling agents, various curing accelerators, low stress imparting agents such as rubber and silicone, etc. as appropriate.・Can be combined.

A general method for preparing the sealing resin composition of the present invention as a molding material is to blend a novolac type epoxy resin having an alkyl-modified polyfunctional phenol resin skeleton, a novolac type phenol resin, silica powder, and others, and After sufficiently uniformly mixing with a mixer or the like, the mixture can be further melt-mixed using hot rolls or mixed using a kneader, etc., and then cooled and solidified and pulverized to an appropriate size to form a molding material. Then, this molding material can be applied to sealing, covering, insulating, etc. electronic or electrical components to impart excellent characteristics and reliability.

(Function) The sealing resin composition of the present invention improves the properties in the R region when heated by using (A) a novolac type epoxy resin having an alkyl-modified polyfunctional phenol resin as a backbone.
Also, since moisture absorption is reduced, the solder tip and resin crack resistance after reflow are improved, and moisture resistance deterioration is reduced.

(Examples) Next, examples of the present invention will be described together with comparative examples, but the present invention is not limited to the following examples. "1%" in Examples and Comparative Examples means "% by weight."

Example 1 16% novolac type epoxy resin with skeleton of alkyl-modified polyfunctional phenol resin shown by the following formula, 9% novolac type phenol resin, 74% silica powder, 0.3% curing accelerator, 0 ester wax .3% and silane coupling agent 0.4% are mixed at room temperature, and further 90-9%
After kneading and cooling at 5° C., the mixture was pulverized to obtain a molding material (A).

Examples 2 to 3 Molding materials (B) and (C
) was obtained.

Comparative Example 1 Orthocresol was used instead of the epoxy resin in the example.
Novolac type epoxy resin (epoxy equivalent: 215) 1
7%, and additionally 8% novolac type phenolic resin.
Silica powder 74%, curing accelerator 0.3%, ester wax 0.3%, and silane coupling agent 0.4%
were mixed to obtain a molding material <D) in the same manner as in the example.

Comparative Example 2 The following trifunctional epoxy resin (epoxy equivalent: 170
) 16%, The molding materials (A) to (E) were transfer-injected into a mold heated to 170°C, and the molded product was cured and sealed. The properties of this molded article were tested and the results are shown in Table 2, and the remarkable effects of the present invention were obtained.

Novolac type phenolic resin 9', silica powder 74
%, curing accelerator 0.3%, ester wax 0.3
% and 0.4% of a silane coupling agent were mixed to obtain a molding material (E).

Products obtained in Examples 1 to 3 and Comparative Examples 1 to 2
A molded article of 11M was made and left in saturated steam at 127° C. and 2.5 atm for 24 hours, and the weight increase was measured.

*2: A molded article similar to that used in the water absorption test was made, and this was post-cured at 175°C for 8 hours to form a test piece of an appropriate size, and measured using a thermomechanical analyzer.

*3: According to JIS-6911.

*4: Using a sealing resin composition (molding material), a silicon chip (test element) with two or more aluminum wirings is adhered to a normal 4270 frame,
After transfer molding at 175°C for 2 minutes, 17
Post-curing was performed at 5° C. for 8 hours. The thus obtained molded product was previously subjected to moisture absorption treatment at 40°C, 790%, for 100 hours, and then immersed in a 250°C solder bath for 10 seconds. Thereafter, a pressure pull test (PCT) was conducted in saturated steam at 127°C and 2.5 atm, and wire breakage due to aluminum corrosion was evaluated as a defect.6 [Effects of the Invention] From the above explanation and Table 2, As described above, the encapsulating resin composition of the present invention is less affected by moisture absorption, has excellent moisture resistance especially after immersion in a solder bath, and soldering heat resistance, is free from internal resin cracks, and is resistant to disconnection due to electrode corrosion and moisture. The occurrence of leakage current can be significantly reduced, and reliability can be guaranteed over a long period of time.

Claims (1)

[Scope of Claims] 1(A) A novolak-type epoxy resin whose skeleton is an alkyl-modified polyfunctional phenol resin obtained by reacting an alkyl-modified hydroxybenzaldehyde with an alkyl-modified phenol (provided that the alkyl group of the alkyl-modified hydroxybenzaldehyde is C_mH_2_m_+_1, where m represents an integer of m≧1, and the alkyl group of the alkyl-modified phenol is C_nH_2_n_+_1, where n is 10≧n≧
(represents an integer of 1) (B) novolac type phenol resin and (C) silica powder are essential components, and the above (C) is added to the entire resin composition.
A sealing resin composition containing 50 to 90% by weight of silica powder.