JPH0239448A - Film carrier tape - Google Patents

Abstract

PURPOSE:To suppress the thermal contraction of a film carrier tape caused by heat at the time of inner lead(IL) bonding by employing a metal foil such as a copper foil as the base film of the film carrier tape. CONSTITUTION:The base film of a film carrier tape is composed of a copper foil 1 and a lead 3 composed of a copper foil is formed on the copper foil 1 with adhesive 2 between. With this construction, as the copper foil 1 is employed as the base film, the thermal contraction of the film carrier tape caused by heat at the time of inner lead(IL) bonding is influenced by the adhesive 2 only and the thermal contraction can be suppressed to the extent less than 0.01%. Therefore, outer lead (OL) bonding pads on a printed board or the like can be aligned with the OL bonding parts of IC leads accurately, so that a short circuit between the OL bonding pads adjacent to each other can be almost eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a film carrier tape, and particularly to the structure of a film carrier tape that requires high-density packaging.

[Conventional technology]

As shown in Figure 3, the conventional film carrier tape is
Sprocket balls for transport and positioning (not shown)
An insulating film 10 made of polyimide or the like having a hole 4 into which a semiconductor chip (hereinafter referred to as an IC chip) 11 is inserted is used as a base film, and a metal foil such as copper is fixed onto this insulating film 10 with an epoxy adhesive 2 and then patterned. However, it had a structure in which a lead 3 having a finger 3A projecting above the hole 4 and a pad (not shown) for electrical selection was formed.

Then, the tip of this finger 3A and the IC chip 11
The bump 12 provided on the surface of the film carrier tape is bonded to the bump 12 by thermocompression bonding or eutectic method, electrical selection and bias test are carried out in the state of the film carrier tape, and then the lead including the finger 3A is cut to a desired length. disconnect. At this time, in the case of multiple bottles with a large number of leads, in order to prevent the cut part of the leads, that is, the outer lead part, from falling apart, the insulating film 10 constituting the film carrier tape is left at the outer end of the outer lead. method is often used. Next, outer lead bonding (hereinafter referred to as OL bonding) is performed to bonding pads on, for example, a printed circuit board or a general lead frame.

With the film carrier tape mentioned above, bonding can be done at once regardless of the number of leads, so it is fast, and the bonding assembly and electrical selection work can be automated, making it suitable for mass production. It has the following advantages.

[Problem to be solved by the invention]

In the inner lead bonding (hereinafter referred to as IL bonding) of IC chips using the conventional film carrier described above, the film carrier glue 3 and I
Approximately 400 to 500 for adhesion to bump 12 on C chip
℃ heat is required. When IL bonding is performed using this heat, the heat is transmitted to the insulating film 10 of the film carrier through the leads 3, causing thermal contraction of the insulating film 10.

For example, in the case of a polyimide film, this shrinkage amount is
The bonding time is a few seconds, but the heat is about 400~5
Because it is 00℃, a thermal contraction of about 0.3% occurs, for example, 10
For a length of mm, there is a contraction of 30 μm. Here O
The number of leads in the L bonding part is 200 to 300 or more,
When the pitch is 150μm or less, the end lead part is 22.5μm or less.
Since it shrinks by ~33°8 μm, it has the disadvantage that it short-circuits with the adjacent bonding butt during OL bonding.

[Means to solve the problem]

The film carrier tape of the present invention is a film carrier tape having a base film having a hole for a semiconductor chip and a lead fixed on the base film, the base film being formed of metal foil. It is.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a sectional view of a first embodiment of the invention.

In FIG. 1, the base film constituting the film carrier tape consists of a copper foil 1 with a thickness of 35 to 70 μm, for example, and a lead made of silver foil with a thickness of 35 μm, for example, is attached to this copper foil via an epoxy adhesive 2. 3 is formed.

According to the first embodiment configured in this way, since the copper foil 1 is used as the base film, the amount of thermal contraction of the film carrier tape due to heat when performing IL bonding is the same as that of the adhesive material 2. The thermal shrinkage can be suppressed to about 0.01% or less. For this reason,
Since the OL bonding pad on the printed circuit board and the OL bonding portion of the IC lead can be accurately aligned, short circuits with adjacent OL bonding pads are almost never generated during OL bonding. Further, the use of metal foil as a base film for an insulating film such as polyimide has the advantage of being inexpensive. FIG. 2 is a sectional view of a second embodiment of the invention.

In the second embodiment, the base film of the film carrier tape is formed from a copper foil 1 as in the first embodiment, and a film having a thickness of 0.5 to 2 μm, for example, A
An insulating film 5 such as 203 is formed, and leads 3 having fingers 3A are further formed with an adhesive 2 interposed therebetween.

By using metal foil as the base film and forming the insulating film 5 on its surface, the heat conductivity, heat dissipation, and mechanical strength are improved when IL bonding is performed. It is possible to suppress the thermal shrinkage caused by this to less than 0.00%. In addition, since silver foil is used as the base film, forming an insulating film 5 such as A20B on this surface improves the electrical insulation with the surface glue 3, and the electrical insulation in the film carrier state is improved. Even in the case of products that undergo screening, there is no need to worry about electrical short circuits.

In the above embodiment, the case where silver foil was used as the base film was explained, but other metal foils such as aluminum foil can be used.

〔Effect of the invention〕

As explained above, the present invention uses metal foil such as copper as the base film constituting the film carrier tape, thereby reducing the amount of thermal shrinkage of the film carrier tape due to heat when performing IL bonding. can. Therefore, the dimension of the OL bonding part of the lead is I
Since there is almost no change before and after L bonding, it is possible to accurately align the OL bonding pad on the printed circuit board with the OL bonding pad of the IC lead, so short circuits with adjacent OL bonding pads almost never occur. That will no longer be the case.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views of first and second embodiments of the present invention, and FIG. 3 is a cross-sectional view of a conventional film carrier tape. 1...Copper foil, 2...Adhesive material, 3...Lead, 3A
... Finger, 4... Hole, 5... Insulating film, 10
...Insulating film, 11...IC chip, 12...
·bump. 1. Copper layer 2 Ding 艷尾 male 3 Lie F ゛ Tsume Fi 7 force ° - 4 Rashi F 5 Kasubayashi 〉 10 Separation layer 17'IC")'・z pu 12 Bump east map number ? Figure number sword

Claims (1)

[Claims] 1. A film carrier tape comprising a base film having holes for semiconductor chips and leads fixed on the base film, wherein the base film is made of metal foil.