JPS6151076A - Adhesive tape - Google Patents

Abstract

PURPOSE:To provide an adhesive tape which has excellent heat resistance and does not allow-leakage current to flow therethrough, by using an adhesive contg. a phenolic resin. CONSTITUTION:A substrate such as a polyimide film is coated with an adhesive obtd. by mixing a phenolic resin witha material selected from among acrylonitrile resin, acrylate ester, epoxy resin and acrylontrile/butadiene copolymer. USE:Fixation of lead frames between pins for resin-sealing type semiconductors.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an adhesive tape for fixing between pins of a lead frame used in a resin-sealed semiconductor.

[Conventional technology]

Conventionally, adhesive tapes for fixing between the pins of lead frames have been made by synthesizing polyacrylonitrile resin, polyacrylic acid ester resin, epoxy resin, or acrylonitrile-butadiene copolymer onto a support film, such as a polyimide film. Adhesive tapes coated with rubber-based resins, etc. alone or in combination are used.

When manufacturing resin-encapsulated semiconductors, the semiconductor is mounted on a lead frame whose pins are fixed with such adhesive tape, and after the semiconductor is fixed to the frame, the pins of the frame and semiconductor terminals are bonded, and then the semiconductor terminals are bonded to the frame pins. The product is sealed with resin.

(Problem to be Solved by the Invention) When a product made in this way is subjected to a characteristic test using the so-called pressure tester test (pressure: 2 atm, temperature: 121°C), the tape portion gradually changes over time as the test elapses. The phenomenon of conduction and current flow became noticeable, and at the start of the pressure pump test, from t0-14 to t-Q.
After 500 hours of current conduction (hereinafter referred to as current leak), which was about -Is ampere, it became 10-4 to 1O-
It varies up to about 5 amperes.

It is said that the current leakage value after 500 hours of the pressure tester must be smaller than about 10-9 amperes to cause problems in practical use.

Means for Solving Problem C] In view of the above circumstances, the present invention has been made through intensive studies to develop an adhesive tape with low current leakage.2 A phenolic resin is used as at least one component of the adhesive. We have discovered the surprising fact that this current leakage value can be significantly reduced by doing so, and have arrived at the present invention.

Adhesive tape for fixing between lead frame pins must naturally have the necessary performance as an adhesive tape, such as appropriate adhesiveness, flexibility, hardness, and heat resistance.
As the adhesive material, an appropriate material is selected from acrylonitrile resin, acrylic acid ester, epoxy resin, acrylonitrile butadiene copolymer, Buclar resin, etc., and these appropriately selected adhesives and phenol resin are mixed. This purpose can be achieved by using and preparing adhesives.

Although the phenolic resin can be used alone, better results can be obtained by mixing the phenolic resin with other resins such as those mentioned above in order to give the adhesive tape more desirable properties. The mixing ratio cannot be determined simply, depending on the type of resin used in combination, fireflies, etc., but it is necessary to use only phenolic resins in order to impart appropriate properties to the adhesive tape and to keep the current leakage value small. However, it is necessary to decide the type and amount of other resins to be mixed and used.

〔Example〕

This will be explained below using examples.

Example 1 The above resin was dissolved in methyl ethyl ketone to prepare a coating liquid,
Coated on a 50 μII polyimide film (manufactured by Kapton DuPont) using a reverse roll and dried, approximately 25 t1
A 1N adhesive layer was formed to prepare a tape.

A small piece with a width of 21111111% and a length of 10 mm was made from this tape and used as a fixing tape for a lead frame. A semiconductor was mounted on a lead frame whose pins were fixed with this film piece, and after fixing the semiconductor to the frame, the pins of the frame and semiconductor terminals were joined and sealed with epoxy resin to prepare a sample. The same solution was dissolved in methyl ethyl ketone to prepare a coating solution, and the solution was applied onto 50 parts of Kapton film to make an adhesive tape. A semiconductor package was similarly made using this tape. A pressure test was conducted on these samples, and as shown in Figure 1, the ones using the adhesive tape of the present invention had an initial current leakage value of 1 (1-1 s ampere), but the current leakage value was 500 amps. Even after the passage of time, the current was good as it only changed to 10"" 13 amperes, whereas the comparative treatment using adhesive tape had 5 amperes.
The current leakage value after 00 hours had decreased to 10-5 amperes.

Example 2 A tape was prepared in the same manner as in Example 1 by providing an adhesive layer having the composition shown below on a Kapton film of 50 DI and 11 thickness.

80 parts of a novolac type phenol resin was blended with 100 parts of a copolymer consisting of the following. A resin molded semiconductor was created using a lead frame using this tape in order to fix between the pins of the lead frame.

FIG. 2 shows the results of a pressure test carried out on these samples.

The initial value of the current leakage value for the one containing phenolic resin was 1 O-'' ampere, but after 500 hours, the current leakage value remained at IQ-12 ampere, whereas the current leak value for the one containing phenolic resin was 500 ampere. After a period of time, it decreased to 10-' amperes.

Example 3 A sample was prepared in exactly the same manner as in Example 1, except that an adhesive with the following composition was used.

At the same time, an adhesive tape provided with an adhesive layer having the composition shown below and containing no phenol resin was used as a comparison sample.

The results of the pressure kicker test are shown in Figure 3. As shown in Figure 3, samples using adhesive tapes with adhesives containing phenolic resins show significantly better changes in current leakage values than tapes with adhesive layers with compositions that do not contain phenolic resins. Recognize.

〔Effect of the invention〕

As is clear from the above, the adhesive tape according to the present invention has no current leakage, has good heat resistance, and is highly practical as a tape for semiconductors.

[Brief explanation of drawings]

The figure shows the relationship between the elapsed time and leakage current of the pressure pump test. 1 to 3 are diagrams showing measured values in the implementation of the present invention.

Claims (1)

[Claims] An adhesive tape for fixing between pins of a lead frame, characterized in that at least one component of the material constituting the adhesive is a phenol resin.