JPS63234013A - Resin composition for semiconductor sealing use - Google Patents

Abstract

PURPOSE:To obtain the titled composition causing no corrosion of aluminum electrodes and/or copper fine wires even if water infiltrated into packages, by incorporating an epoxy resin with benzotriazole (water-soluble amine salt) as the rust preventive. CONSTITUTION:The objective composition can be obtained by incorporating (A) 100pts.wt. of an epoxy resin with (B) as the rust preventive, pref. 0.1-2pts. wt. of benzotriazole or a water-soluble amine salt therefrom (e.g., benzotriazole monoethanolamine salt).

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a resin composition for sealing a semiconductor in which a semiconductor element and an external connection lead are bonded using gold, a gold alloy, or a copper bonding wire.

More specifically, the present invention relates to a composition in which benzotriazole or a rust preventive agent prepared by adding various amine salts to benzotriazole is added to a resin for semiconductor encapsulation.

(Prior art) Conventionally, most semiconductor devices such as transistors and IC5LSIs are protected from external environmental changes such as temperature, humidity, and pollutants after bonding electrodes on the semiconductor device and external connection leads with gold or gold alloy thin wires. It is packaged with a sealing resin to protect the external connection leads, insulate them individually, and prevent damage and changes in device characteristics due to mechanical vibration and impact.

The properties required for these sealing resins vary depending on the package form and size, but they must have high moisture resistance, good workability, low stress, high thermal conductivity, and thermal shock resistance. Requested accordingly. Commonly used resins include epoxy resin, silicone resin,
Alkind resin etc. are used.

(Problems to be Solved by the Invention) Although wires have excellent bonding properties, they are expensive, so the use of precious metals is being promoted, and there is a problem of replacing them with copper-based bonding wires as an alternative metal material. be.

In addition, the rapid innovation in semiconductor production technology has progressed at a remarkable pace over the years, and its functions and forms have become more diverse. There is a tendency for devices to become more complex and multi-functional, and their packaging forms, sizes, and mounting methods are also diversifying.

For example, when bonding wires are bonded, a ball formed at the tip of a thin wire with a diameter of 25 to 30 μm is connected to a 100 mm diameter wire on a semiconductor element.
Since the bond is bonded to an aluminum vapor-deposited electrode with a diameter of ~130 μm, consideration must be given to corrosion resistance against environmental changes as well as the reliability of the bonded portion. Although thin gold wires are chemically stable, thin copper wires are easily oxidized and lack corrosion resistance against environmental changes.
This is a dissimilar junction of aluminum, and depending on the presence of moisture, it can form a local battery, causing problems such as corrosion of the aluminum and inhibiting the functionality of semiconductor devices.

On the other hand, the resin for encapsulating semiconductor devices has the following required properties (■ low molding shrinkage, linear expansion coefficient of the cured product returns to the metal frame, good adhesion to external leads, ■ ionicity) Low content of impurities, ■ Good thermal conductivity, ■ Good fluidity during molding, short molding time, and easy release.

Good moldability, ■Mold is dirty (and there is little dust)
Epoxy resins and silicone resins are used.

However, in general, epoxy resins are purified by removing excess liquid and low molecular weight by-products and removing sodium chloride produced by dehalogenation reaction.
By-products as shown in FIGS. 1(A) and 1(B) remain in the epoxy resin.

Figure 1 (F3) )-to-CH2-CH-CH2-C1
However, there is a problem in that these chlorine is liberated, corroding the aluminum electrode, and significantly reducing the moisture resistance reliability of semiconductor products.

In addition, since the area ratio is large in the DIP of an insertion type device,
Surface mount device 7 for thinner and smaller multi-pin applications,
(7) SOPs, FPs, PLCCs, etc. are rapidly becoming popular, but these surface mount devices have a problem in that their moisture resistance reliability decreases significantly after mounting. The cause of this is that the package absorbs moisture during the process of molding the package with the sealing resin, post-curing, and mounting, and when exposed to the solder melting temperature during soldering, the absorbed moisture expands explosively, and this vapor pressure causes the package to absorb moisture. This is because M separation occurs at the interface between the semiconductor element and the resin, and moisture infiltrates into this peeled part, corroding the aluminum electrode on the semiconductor element.

The present invention aims to solve this problem. Even if the sealing resin contains a small amount of ionic impurities, the package absorbs moisture and expands explosively during soldering. However, even if the vapor pressure causes peeling at the interface between the semiconductor element and the resin, and moisture infiltrates into the peeled part, this resin composition for semiconductor encapsulation can prevent corrosion of the aluminum electrodes and thin copper wires on the semiconductor element in the package. It's about providing things.

(Means for Solving the Problems) As a result of intensive studies to solve the above-mentioned object, the present inventors have found that benzotriazole or a water-soluble amine salt of benzotriazole is added to an epoxy resin for semiconductor encapsulation. By including a small amount of ionic impurities in the resin, and even if water enters the package, the problem of soft soil can be eliminated, and corrosion of aluminum electrodes and thin copper wires on semiconductor elements can be completely prevented. The present invention was completed by discovering that this can be prevented.

The present invention is characterized in that benzotriazole or a water-soluble amine salt of benzotriazole is contained in the epoxy resin.

The configuration of the present invention will be explained below.

The epoxy resin used in the present invention is selected from cresol, phenol novolak type compound, acid anhydride, and phenol resin as the main resin, but novolac type epoxy resin is used for low pressure transfer sealing resin. A curing accelerator such as an imidazole compound is used in combination with the phenol resin, and other additives include fillers such as silica and alumina, flame retardant aids such as antimony dioxide, and appropriate amounts of pigments and mold release agents. This is an epoxy resin for semiconductor encapsulation with a known formulation.

The water-soluble amine salts of benzotriazole used in the present invention include benzotriazole monoethanol, benzotriazole diethylamine salt, and benzotriazole diethylamine salt.
Cyclohexylamine salt, benzotriazole/morpholine salt, benzotriazole/diisopropylamine salt, benzotriazole/isopropylamine salt, methylbenzotriazole/cyclohexylamine salt, etc., which are made water-soluble by adding various amines to benzotriazole. This is what I did.

The amount of benzotriazole or water-soluble amine salt of benzotriazole used is 0.01 to 5 parts by weight, preferably 0.1 to 2 parts by weight, based on 100 parts by weight of the epoxy resin as the main resin.
Parts by weight range. If the amount used is less than 0.01 part by weight, no epoxy can be formed and no anticorrosion effect can be expected.

On the other hand, if the amount exceeds 5 parts by weight, no improvement in the anticorrosion effect corresponding to the amount used will be observed, and saturation will be reached, resulting in an economic disadvantage. This is not preferable because it impedes workability.

(Function) In the present invention, since the epoxy resin contains benzotriazole or a water-soluble amine salt of benzotriazole in advance, moisture that corrodes the aluminum electrodes and thin copper wires on the semiconductor element does not enter the package. However, by utilizing this moisture, benzotriazole or a water-soluble amine salt of benzotriazole is eluted into the epoxy resin, forming a strong anti-corrosion film on the surface of the aluminum electrode or thin copper wire. Even if they are affected by minute amounts of ionic impurities that remain during the purification process and moisture that enters, the aluminum electrodes and thin copper wires will not be corroded at all.

(Example) Novolak epoxy resin for semiconductor sealing containing various benzotriazole/ethanolamine salts was molded by low-pressure transfer molding to form a 12-pin DIP-IC.
was created (Note 1). We conducted molding workability (Note 3) and PCT tests (Note 2) for each package.
The number of defective pieces was investigated and the results are also listed in Table 1.

(Note 1) The 12-pin DIP-IC used for the test has a 25μ diameter
This was done using a copper bonding wire.

(Note 2) The PCT test is a corrosion acceleration test under high temperature and high humidity, with a pressure of 2 atmospheres, humidity of 100%, and humidity of 1
Each package was left outside at 21° C., and the number of defective semiconductors over time was determined.

(Note 3) Molding workability evaluates molding cycle and mold sewage problems.

As can be seen from the results, Examples 1 to 4 were very good despite the severe conditions of the PCT test, but Comparative Example 1 had insufficient amount of benzotriazole/ethanolamine salt. Comparative Example 2, which is unfavorable because the number of defects tends to increase after 500 hours, is unfavorable because the amount of benzotriazole/ethanolamine salt is too large, resulting in poor molding workability.
CT examination was not performed.

Although not shown in the results, after the aluminum electrodes on the semiconductor element and the external leads are bonded using gold or gold alloy bonding wires, which are currently used in large quantities, packaging is performed using the sealing resin according to the present invention. Then, the same results as in the example can be obtained. In addition, by using a sealing resin containing benzotriazole or a water-soluble amine salt of benzotriazole in silicone resin, alkyd resin, etc.
Similar to the present invention, it can be expected to prevent corrosion due to moisture entering semiconductor junctions, that is, thin gold wire-aluminum electrode and thin copper wire-aluminum electrode.

(Effects of the Invention) As explained above, the present invention uses a resin for semiconductor encapsulation in which benzotriazole or a water-soluble amine salt of benzotriazole is pre-contained in an epoxy resin. Even if moisture that corrodes the aluminum electrodes and thin copper wires on the device infiltrates into the package, this moisture will be used to elute benzotriazole or a water-soluble amine salt of benzotriazole, which will corrode the aluminum electrodes and thin copper wires. Since a strong anti-corrosion film is formed on the surface, aluminum electrodes and fine copper wires will not be corroded even if they are affected by infiltrating moisture or trace amounts of ionic impurities remaining in the epoxy resin refining process. This makes it possible to further improve the reliability of the package after it is mounted.

Claims (1)

[Claims] A resin composition for semiconductor encapsulation, characterized in that an epoxy resin contains benzotriazole or a water-soluble amine salt of benzotriazole.