JPH05183016A - Tab tape carrier - Google Patents

Abstract

PURPOSE:To improve the resistance to whisker and make it possible to enhance the reliability of a semiconductor device by providing a specific thin copper plating interstitially between a copper lead and tin plating. CONSTITUTION:A tin plating 4 is applied to the surface of a copper lead 2 having a given pattern which is bonded on an insulating film 1. In such a TAB tape carrier, a thin copper plating 5 having the glossiness of 200 (measured by densitometer) or more, and grain size of 3mum or less is interstitially provided between the copper lead 2 and tin plating 4. A copper foil is laminated on the surface of the film tape 1 through an adhesive agent 3, and the copper lead 2 is formed by photoetching, for example. By a pulse plating method, an electric copper thin plating (in the thickness of 0.3 to 0.5mum) is provided for the copper lead 2 thereby to form the copper plating 5 having the glossiness of 200 or more and grain size 3mu or less on the surface of the copper lead 2. Then, by an electroless plating (temperature of plating solution: 60+ or -1 deg.C), the tin plating 4 of 0.5 to 1.0mum thick is formed on the surface of the copper plating 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is a TAB (Tape Automated) which is one of mounting methods for semiconductor elements such as IC and LSI.
The present invention relates to a TAB tape carrier used in the Boding method, and particularly to a TAB tape carrier having a significantly improved whisker resistance.

[0002]

2. Description of the Related Art In recent years, automation of semiconductor element mounting technology has been
Further, in order to increase the speed, a TAB (Tape Automated Bonding) method is adopted in which semiconductor elements such as ICs and LSIs are incorporated into a long tape carrier by wireless bonding.

FIG. 3 shows the structure of a conventional TAB tape carrier. The tape carrier 10 is formed by bonding a copper foil onto a flexible insulating film tape 1 made of polyimide, polyester or the like, and forming a copper lead 2 having an outer lead 14 and an inner lead 15 by photoetching.

The film tape 1 has a device hole 11 for accommodating semiconductor elements (not shown) such as IC and LSI, a sprocket hole 12 for carrying and positioning a film, and an outer for taking out electric signals. The hole 13 is formed by punching.

The copper lead 2 is obtained by laminating a copper foil on the surface of the film tape 1, applying a photosensitive resist to the copper foil, drying the copper foil, exposing it through a photomask having a predetermined pattern, and further developing it. It is formed by forming a photoresist layer having a predetermined pattern and then etching the photoresist layer as a mask.

When the copper lead 2 is formed in this manner, a semiconductor device (IC chip) is placed in the device hole 11, and the minute electrodes formed on the IC chip and the corresponding inner lead 15 on the tape are placed. , Thermocompression bonding with a heated bonding tool. At this time, tin plating is applied to the surface of the copper lead in order to enable bonding at a relatively low temperature. FIG. 4 shows a cross-sectional structure of the tape carrier 10 having such a structure, and the film tape 1
A tin lead 4 is applied to the surface of the copper lead 2 adhered to the via via an adhesive 3, and the tin plating 4 and the Au bump provided on the electrode of the IC chip are eutectic bonded. There is.

[0007]

However, the conventional TAB
According to the tape carrier for whiskers, whiskers (needle-shaped crystals called "beard") are easily generated from the tin plating applied to the surface of the copper lead. As one of the causes of this, the interface distortion stress caused by the difference in the size of the underlying copper foil crystal grains and the size of the tin-plated grains is considered. Once generated, whiskers grow rapidly (30-40 μm length /
Therefore, there is a risk of short-circuit failure between leads.
This causes a decrease in reliability as a semiconductor device.

Therefore, the object of the present invention is to improve the whisker resistance and the reliability of the semiconductor device TA.
A tape carrier for B is provided.

[0009]

In view of the above problems, the present invention has a gloss level of 200 between the copper lead and the tin plating in order to improve the whisker resistance and the reliability of the semiconductor device.
(Digisitometer measurement) As described above, the present invention provides a TAB tape carrier in which a thin copper plating having a grain shape of 3 μm or less is interposed.

The copper lead is composed of electrolytic foil or rolled foil. The copper plating applied to the surface of the copper lead is formed by, for example, a pulse plating method in an acidic copper plating bath to a thickness of 0.3 to 0.5 μm. The conditions at this time are an average current density of 5 A / dm ² and a frequency. 100Hz, 10% duty circle. Further, the tin plating applied to the surface of the copper plating is formed in a thickness of 0.5 to 1.0 μm in an acidic tin plating bath by an electroless plating method, and the conditions at this time are liquid temperature 60 ± 1 ° C. and immersion. The time is 4 to 6 minutes.

[0011]

In the TAB tape carrier of the present invention having the above-mentioned structure, since the surface of the underlying copper foil is thinly and densely copper-plated, the compatibility with the tin-plated particles can be improved and the interface distortion stress can be improved. And the generation of whiskers from the conductor pattern can be suppressed.

[0012]

The tape carrier for TAB of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows a TAB according to an embodiment of the present invention.
The cross-sectional structure of the tape carrier 20 is shown in FIG.
Since the tape carrier 10 shown in FIG. 6 has substantially the same basic structure as that of FIG. This tape carrier 2
0 indicates a glossiness of 2 between the copper lead 2 and the tin plating 4 which are laminated on the surface of the film tape 1 via the adhesive 3.
It has a configuration in which a thin copper plating 5 having a grain shape of 3 μm or less is interposed between 00 (measured by a digital cytometer).

In the tape carrier 10, a copper foil is laminated on the surface of the film tape 1 via an adhesive 3, and the copper foil is subjected to the above-mentioned photo-etching (application of a photosensitive resist, exposure and development to form a pattern). After baking, etching is performed) to form the copper leads 2 on the surface of the film tape 1, and thin copper electroplating (thickness 0.3 to 0.5 μm) is performed on the copper leads 2 by the pulse plating method. On the surface of the lead 2, a copper plating 5 with a gloss of 200 (measured by a digisisitometer) or more and a grain shape of 3 μm or less is formed, and the copper plating 5 is applied by electroless plating (plating solution temperature 60 ± 1 ° C.)
It is manufactured through each step of forming a tin plating 4 having a thickness of 0.5 to 1.0 μm on the surface of.

Next, the tape carrier 20 thus obtained and the conventional tape carrier 10 are placed at room temperature and 40
Generation of tin whiskers and growth thereof were observed after storage in an atmosphere of 65 ° C. and a humidity of 65 ° C./95%.
Note that the conditions of 40 ° C. and 65 ° C./95% humidity are set in consideration of past experiments, literatures, and reliability of semiconductor mounted products.
It was selected as a condition to promote the generation and growth of whiskers.

FIG. 2 shows the above experimental results. The whisker length of the tape carrier 20 of the present invention after storage for one month in room temperature storage is 10 μm or less.
It can be seen that it is reduced to 1/3 to 1/4 as compared with 0. Also, under the conditions of 40 ° C. and 65 ° C./95% humidity, it is found that the tape carrier 20 of the present invention surely reduces the growth of whiskers as compared with the conventional tape carrier 10.

As described above, according to the present invention, by interposing the copper plating 5 between the copper lead 2 and the tin plating 4, the whisker resistance of the conductor pattern can be improved. This is because the thin and dense copper plating 5 is provided on the surface of the copper lead 2 to improve the compatibility with the particles of the tin plating 5 to reduce the interface distortion stress.

[0018]

As described above, according to the TAB tape carrier of the present invention, between the copper lead and the tin plating,
Gloss level 200 (measured by digisistometer) or more, grain shape 3μ
Since the thin copper plating having a thickness of m or less is interposed, the whisker resistance of the conductor pattern can be improved, a short-circuit failure between leads can be prevented, and the reliability of the semiconductor device can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view of a tape carrier showing an embodiment of the present invention.

FIG. 2 is a graph showing the growth of tin whiskers.

FIG. 3 is an explanatory view showing a conventional tape carrier.

FIG. 4 is a sectional view showing a conventional tape carrier.

[Explanation of symbols]

1 film tape 2
Copper lead 3 Adhesive 4
Tin plating 5 Copper plating 10
Tape carrier 11 Device hole 12
Sprocket hole 13 Outer hole 14
Outer lead 15 Inner lead

Claims (1)

[Claims] 1. A tape carrier for TAB, which is obtained by applying tin plating to the surface of a copper lead having a predetermined pattern adhered on an insulating film, wherein a gloss level of 200 (digitisite) is provided between the copper lead and the tin plating. A tape carrier for TAB, characterized in that a thin copper plating having a grain shape of 3 μm or less is interposed.