JPH0216147A - Sealing resin composition - Google Patents

Abstract

PURPOSE:To form a sealing resin composition less affected by absorbed water, being excellent in, especially, humidity resistance and soldering-heat resistance after being immersed in a soldring bath and having high reliability by mixing a specified polyepoxy resin with a polyphenol resin and a silica powder. CONSTITUTION:This sealing composition essentially consists of a polyepoxy resin of formula I or II (wherein n is 0 or an integer >=1; R is CmH2m+1, and m >=0), a polyphenol resin of formula III or IV (wherein n is 0 or an integer >=1; R is CmH2m+1; and m >=0), and 50-90wt.%, based on the total resin composition, silica powder. As the silica powder, one having a low impurity content and a mean particle diameter <=30mum is desirable.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a sealing resin composition that has excellent moisture resistance and solder 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 processes for assembling semiconductor devices has been promoted. For example, when a semiconductor device in a flat package is attached to a circuit board for the first time, each lead pin has traditionally been soldered, but recently a solder dipping method or a solder reflow method has been adopted.

(Problem to be Solved by the Invention) In a semiconductor device sealed with a conventional resin composition consisting of an epoxy resin, a novolac type phenol resin, and a silica powder, the reliability of the semiconductor device decreases when the entire device is immersed in a solder bath. There was a drawback to doing so. In particular, if a semiconductor device that has absorbed moisture is immersed in solder, peeling or internal resin cracks may occur between the encapsulating resin and the semiconductor chip or between the encapsulating resin and the lead frame, resulting in significant moisture resistance deterioration, wire breakage due to electrode corrosion, and leakage due to moisture. It has the disadvantage that it generates electric current and cannot guarantee long-term reliability.

The present invention has been made to solve the above-mentioned drawbacks, and has little influence of moisture absorption, and even if the entire semiconductor device is immersed in a solder bath or soldered reflowed, it will not peel off from the semiconductor chip or lead frame or cause internal resin cracks. An object of the present invention is to provide a resin composition for sealing that has excellent moisture resistance and soldering heat resistance and is highly reliable over a long period of time, and does not cause disconnection due to electrode corrosion or leakage current due to moisture due to deterioration of moisture resistance. It is.

[Structure of the Invention] (Means for Solving the Problems) As a result of intensive research aimed at achieving the above object, the present inventors have discovered that glass can be produced by using specific polyfunctional epoxy resins and polyfunctional phenolic resins. The present invention was completed based on the discovery that a composition with an increased transition temperature and improved mechanical properties and soldering heat resistance during heating can be obtained.

That is, the present invention provides (A) a polyfunctional epoxy resin represented by the following formula (I) or (n) (f!F, L, where n is an integer of 0 or 1 or more, Ctn
H2m ++ , l'n≧O) (B) A polyfunctional phenolic resin represented by the following formula (II[) or (IV) formula... (R is ■... (IV) (However, In the formula, n is 0 or an integer of 1 or more, R is C, H2□
1,1≧0) (C) silica powder is an essential component, 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.

The polyfunctional epoxy resin (A) used in the present invention is one represented by the above formula (I) or (II>, and as long as it has the above-mentioned skeleton structure in its molecule, the molecular weight is particularly limited to #I. It is widely covered.

These epoxy resins are at least trifunctional or tetrafunctional epoxy resins. Examples of specific epoxy resins include the following.

These polyfunctional epoxy resins can be used alone or in a mixture of two or more. The above polyfunctional epoxy resin (A) may be mixed with a novolak epoxy resin represented by the following general formula.

Examples include polyfunctional phenolic resins.

(However, in the formula, R1 represents a hydrogen atom, a halogen atom, or an alkyl group, R2 represents a hydrogen atom or an alkyl group, and n represents an integer of 1 or more.) As the polyfunctional phenol resin (B) used in the present invention,
Those having the above formula (I[) or (IV) are broadly included without particular limitation on molecular weight, etc., as long as they have the above-mentioned skeleton structure in their molecules. This polyfunctional phenol resin is at least trifunctional or tetrafunctional phenol resin, and these can be used singly or in combination of two or more types. Specifically, for example,
In addition, (B) the polyfunctional phenol resin may be a mixture of a novolac type phenol resin obtained by reacting phenols such as phenol and alkylphenol with formaldehyde or paraformaldehyde, and modified resins thereof. can.

As the silica powder (C) used in the present invention, commercially available shells are used, but among them, those with a low impurity concentration and an average particle size of 30 μm or less are preferable.
If the average particle size exceeds 30 μI, moisture resistance and moldability will be poor, which is not preferable.

As a blend of silica powder, 5% of the total resin composition is used.
Contain 0 to 90% by weight. If the proportion is less than 50% by weight, the moisture absorption of the resin composition is high, resulting in poor moisture resistance after immersion in solder, which is undesirable. If it exceeds 90% by weight, fluidity is extremely poor, resulting in poor moldability, which is undesirable. . Therefore, it is limited within the above range.

The sealing resin composition of the present invention contains the above-mentioned polyfunctional epoxy resin, polyfunctional phenol resin, and silica powder as essential components, but may optionally contain natural wax, for example, within the scope of the purpose of the present invention. Synthetic waxes, metal salts of linear fatty acids, acid amides, esters, mold release agents such as paraffin, combustion agents such as antimony dioxide, coloring agents such as carbon black, silane coupling agents, various curing accelerators A rubber-based or silicone-based low stress imparting agent can be appropriately added or blended.

The general method for manufacturing the sealing resin composition of the present invention as a molding material is to blend polyfunctional epoxy resin, polyfunctional phenol resin, silica powder, and others, mix sufficiently uniformly with a mixer, etc., and then Further, the mixture can be melt-mixed using heated rolls or mixed using a kneader or the like, and then cooled to solidify and pulverized to an appropriate size to form a molding material.

This molding material can be applied to seal electronic or electrical components, as well as for coating, insulation, etc., and can provide excellent properties and reliability.

(Function) In the sealing resin composition of the present invention, by using a specific polyfunctional epoxy resin and polyfunctional phenol resin, the reaction becomes active to form a three-dimensional network structure, and the glass transition temperature increases.

Therefore, resin crack resistance after solder immersion or solder reflow becomes good. In addition, heat resistance is improved by increasing the glass transition temperature, and mechanical properties under heat are also improved.

(Example) The present invention will be explained by Examples, but the present invention is not limited to the following Examples.6 In the following Examples and Comparative Examples, "%" means "% by weight".

Example 1 17% polyfunctional epoxy resin shown in the following formula, 10% polyfunctional phenolic resin shown in the following formula, 72% silica powder
, 0.3% of curing accelerator, 0.3% of ester wax, and 0.4% of silane coupling agent are mixed at room temperature, further kneaded at 90 to 95°C, cooled, and then crushed to obtain molding material (A). I left ¥A.

Example 2 9% of the polyfunctional epoxy resin used in Example 1, 8% of orthocresol novolak type epoxy resin, 5% of the polyfunctional phenol resin used in Example 1, 5% of phenol novolac type phenol resin, 72% of silica powder %, curing accelerator 0.3%, ester wax 0.3% and silane coupling agent 0.4% are mixed at room temperature, and further 90-95%
A molding material (B) was produced by kneading and cooling at °C and then pulverizing.

Comparative example Orthocresol novolac type epoxy resin 17%,
8% novolac type phenolic resin, 74% silica powder,
A molding material (C) was produced in the same manner as in Example 1 by mixing 0.3% of a curing accelerator, 0.3% of an ester wax, and 0.4% of a silane coupling agent.

Molding materials manufactured in Examples 1 and 2 and comparative examples <A) ~
(C) was transfer-injected into a mold heated to 170° C. and cured to obtain a sealed molded product. The molded products were tested for water absorption, glass transition temperature, bending strength, and PCT after solder immersion, and the results are shown in Table 1. It was possible to confirm the remarkable effects of the present invention.

Table ■ (Units) 1: A molded product with a diameter of 5011 and a thickness of 31 nm was made by l-transfer molding, and was left in saturated steam at 127°C and 2.5 atm for 24 hours, and the weight increase was measured. .

*2: Make the same molded product as in the water absorption test, and test this with 17
After post-curing at 5° C. for 8 hours, a test piece of an appropriate size was prepared and measured using a thermomechanical property analyzer.

*3: Measured according to JIS-6911 6 *4: Using a molding material, a silicon chip with two or more aluminum wirings was glued to a normal 4270 frame and heated at 115°C. 175°C after transfer molding for 2 minutes.

After curing for 8 hours, the molded product thus made was subjected to moisture absorption treatment for 100 hours at 40°C, 90%, and then cured for 2 hours.
It was immersed in a solder bath at 50°C for 10 seconds. After that, 1
Pressure Cooker Test 1~ (PCT) was conducted in saturated steam at 27°C and 2.5 atm, and disconnection due to corrosion of aluminum was evaluated as a defect.6 [Effects of the Invention] As is clear from the above explanation and Table 1. In addition, since the sealing resin composition of the present invention uses a specific polyfunctional epoxy resin and a polyfunctional phenol resin, it is less affected by moisture absorption.
It has excellent moisture resistance, soldering heat resistance, and mechanical properties at high temperatures, so even after immersion in solder, the semiconductor chip and lead frame will not peel off or internal resin cracks will occur.
Furthermore, it is highly reliable as it does not cause wire breakage due to corrosion of the electrodes due to moisture deterioration or leakage current due to moisture.

Patent applicant: Toshiba Chemical Corporation

Claims (1)

[Claims] 1(A) A polyfunctional epoxy resin having the following formula (I) or (II) ▲There are mathematical formulas, chemical formulas, tables, etc.▼…(I) ▲There are mathematical formulas, chemical formulas, tables, etc. ▼…(II) (However, in the formula, n is an integer of 0 or 1 or more, R is C_m(I
) H_2_m_+_1, m≧0) (B) Next (I
Polyfunctional phenolic resin represented by formula II) or formula (IV)▲There are mathematical formulas, chemical formulas, tables, etc.▼…(III) ▲There are mathematical formulas, chemical formulas, tables, etc.▼…(IV) (However, in the formula, n is 0 or an integer greater than or equal to 1, R is C_mH_
2_m_+_1, m≧0) (C) silica powder is an essential component, and the above (C) is added to the entire resin composition.
A sealing resin composition containing 50 to 90% by weight of silica powder.