JPH04359443A - Tape carrier for tab - Google Patents

Abstract

PURPOSE:To provide a tape carrier for TAB, which can prevent a disconnection caused by a short circuit or corrosion generated at an opening part in a film tape. CONSTITUTION:In a tape carrier 30 for TAB, both upper and rear faces of a lead 16 provided on the output side of a flexible window 22 in a film tape 13 are coated with a protective material 40, such as an epoxy resin or silicone liquid rubber resistant to an adhesive foreign particle. In addition to this way, a protective sheet 40, such as a polyethylene sheet which is resistant to an adhesive foreign particle, may be stuck thereon.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a TAB tape carrier, and more particularly to a TAB tape carrier having an opening such as a bent window in a portion of the film tape.

0002

[Prior Art] In recent years, in order to automate and speed up the mounting technology of semiconductor devices, TAB (Tape Automated
Bonding) method has been adopted. Such a TAB method is characterized by the flexibility of the tape carrier on which semiconductor elements such as ICs and LSIs are mounted, allowing for three-dimensional mounting by folding. FIG. 4 shows a cross-sectional configuration of a conventional TAB tape carrier 10. As shown in FIG. The TAB tape carrier 10 consists of a film tape 12 made of polyimide or the like, and a film tape 12 formed on it.
It is composed of output lead wires 14 and 16. The film tape 12 has a device hole 18 for storing an LSI (not shown) and an OLB hole (Output) for soldering a printed circuit board (not shown) and an output lead wire 16.
r-lead Bonding Hole) 20,
A bending window 22 is formed in each case to make the film tape 12 easier to bend.

[0003] In such a TAB tape carrier 10, a solder resist (not shown) having a thickness of 20 to 30 μm is formed on the surface of the tape carrier by a screen printing method. This is intended to prevent contamination caused by flux and to protect the wiring pattern from external contaminants. At this time, no solder resist is applied to the lead wires 14 and 16 portions of the device hole 18 and the bending window 22 portion. The reason why resist is not applied to the bending window 22 is that the solder resist ink enters into the bending window 22 through the gap between the lead wires 16 and adheres to the printed wiring board.

0004

[Problem to be solved by the invention] The conventional T as described above
In the AB tape carrier 10, the conductor (lead wire 16) in the bending window 22 portion is not protected.
Foreign matter such as fine metal particles will adhere to this part. This may cause adjacent lead wires to come into contact with each other and cause a short circuit. In particular, in multi-pin type tape carriers, there is a high risk of short-circuiting even if the foreign matter is about 30 μm. In addition, the output lead wire 16 generally has a width of 30 to 50 μm,
Since the spacing is very fine, about 30 to 100 μm, there is a risk of corrosion due to adhesion of moisture, ionic contaminants, etc., which may eventually lead to disconnection, and at the same time, there is a risk of migration short circuit. On the other hand, it is conceivable to plate the lead wires 16 in the bending window 22 portion with tin or solder, but in this case, whiskers may occur and short circuits may occur within about 7 to 30 days after plating is completed by storage at room temperature.

[0005]

[Object of the Invention] The present invention has been made in view of the above points, and provides a tape carrier for TAB that can reliably prevent short circuits and disconnections due to corrosion of the conductor pattern on the opening formed in a part of the film tape. The purpose is to provide.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a protective film with excellent foreign substance adhesion resistance, such as epoxy resin or silicone liquid rubber, on the surface of the conductor pattern on the opening of the film tape. A protective film such as polyethylene that is highly resistant to foreign matter adhesion is attached.

[0007]

[Function] As described above, in the TAB tape carrier according to the present invention, a protective film with excellent foreign matter adhesion resistance is formed on the surface of the exposed conductor pattern on the opening by coating or pasting. Exposed conductor patterns can be well protected from foreign objects without any negative effects. That is, unlike the case where a solder resist is formed on the surface of a conductor pattern by screen printing, the solder resist ink does not enter into the opening and adhere to the printed wiring board.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 shows the surface state of a TAB tape carrier 30 used in a liquid crystal television according to an embodiment,
FIG. 2 shows the cross-sectional structure of FIG. 1 in the Y-Y direction. The TAB tape carrier 30 includes a film tape 12 made of polyimide or the like and a lead wire 1 on the input side.
4, the output side lead wire 16 connected to the fine wiring of the TFT substrate and STN substrate of the liquid crystal substrate 32 (FIG. 3), and the LSI 34 (FIG. 3) at the tips of the input and output side lead wires 14 and 16.
and an inner lead portion 36 connected to the inner lead portion 36. The thickness of the film tape 12 is 75 μm, the thickness of the copper foil (lead wires 14, 16) is 35 μm, and the thickness of the epoxy adhesive (not shown) between the film tape 12 and the lead wires 14, 16 is 20 μm. , Actual inner lead 36
The number is 100, and the width of the TAB tape carrier 30 is 35.
It is mm.

The film tape 12 has a device hole 18 for storing the LSI 34 and an OLB hole (Output) for soldering the output lead wire 16 to the liquid crystal board 32.
r-lead Bonding Hole) 20,
A bending window 22 (opening width 1.5 mm, length 20 mm) for making the film tape 12 easier to bend is formed in each case. In addition, in the TAB tape carrier 30 configured as described above, in order to prevent contamination by flux during soldering work in the OLB hole 20 and to protect the wiring pattern from external contaminants, the device hole 18 is A solder resist 38 having a thickness of 20 to 30 μm is formed by screen printing except for the lead wires 14 and 16 and the bending window 22.

A protective film 40 is formed on both the front and back surfaces of the output side lead wire 16 above the bending window 22. The protective film 40 includes (1) uncured epoxy paint;
(2) Room temperature curing silicone liquid rubber (RTV), (3)
Heat-fusible polyethylene or the like is used. When using an uncured epoxy paint, the uncured epoxy paint diluted with a solvent is sprayed onto both sides of the lead wire 16 using a fine nozzle to form a protective film 40 with a thickness of approximately 5 μm. Note that the thickness of the protective film 40 in this case is 5 μm.
Although not limited to, the thickness is preferably about 1 to 5 μm in order to prevent cracks from occurring during bending. On the other hand, in the case of room-temperature curing silicone liquid rubber, the film thickness is set to about 5 to 20 μm because cracks are less likely to occur. Further, when heat-fusible polyethylene is used, a film-like heat-fusible polyethylene having a thickness of about 10 μm is attached to the surface of the lead wire 16 at 150°C.

FIG. 3 shows a TAB configured as described above.
The tape carrier 30 is shown mounted on a liquid crystal television 50. The TAB tape carrier 30 is bent at the end with the LSI 34 set in the device hole 18 and mounted on the surface of the liquid crystal substrate 32. In this way, by mounting the TAB tape carrier 30 in a bent state, the liquid crystal television 50 can be made smaller. The liquid crystal substrate 32 is provided with wiring using a transparent conductive film, and the TA
It is connected to the output side lead wire 16 of the B tape carrier 30 by an anisotropic conductive film or the like. In addition, in the figure, the code 5
2 is a backlight light source.

Next, a performance test of the TAB tape carrier 30 constructed as above will be explained with reference to Table 1. This test was conducted to detect a short circuit due to whisker formation on the output side lead wire 16 at the top of the bending window 22 on the 30th day after tin plating, and a high temperature and high humidity (65°C, humidity 95°C).
Corrosion breakage after 1000 hours under conditions of
The rate of occurrence of migration short circuits was investigated after applying a DC bias voltage of 28 V to the lead wire 16 for 500 hours at a temperature of 65° C. and a humidity of 95%. TA to be sampled
There are three types of tape carriers for B, including three types according to this embodiment in which a protective film is formed on the lead wire 16, and a conventional product in which a protective film is formed on the lead wire 1.
Using 50 pieces of each type that does not form a protective film in 6,
A test was conducted to determine how many of the 50 TAB tape carriers would cause the above-mentioned short circuit or disconnection. The three types of samples used in Examples are those in which (1) uncured epoxy paint, (2) room temperature curing silicone liquid rubber (RTV), and (3) heat-fusible polyethylene were used as protective films. As is clear from the table, the TAB tape carrier according to this example has a lower incidence of short circuits and disconnections than conventional products.

[0013]

[Table 1]

[0014]

[Effects of the Invention] As explained above, the TA according to the present invention
In the B tape carrier, a protective material with excellent foreign matter adhesion resistance is coated or pasted on the surface of the conductor pattern on the opening formed in the film tape, so there is no possibility of contaminating the printed wiring board. This has the effect of reliably preventing short-circuiting and disconnection of the conductor pattern over the opening due to corrosion, without adversely affecting others.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing the configuration of an embodiment of the present invention.

FIG. 2 is a sectional view taken along the Y-Y direction in FIG. 1;

FIG. 3 is a sectional view showing the state of use of the present invention.

FIG. 4 is a cross-sectional view showing the configuration of the prior art.

[Explanation of symbols]

12 Film tape
32 Liquid crystal board 14 Input side lead wire
34 LSI 16 Output side lead wire
36 Inner lead 18 Device hole
38 Solder resist 20 OLB hole
40 Protective film 22 Bending window
50 LCD TV 30 TAB tape carrier
52 Backlight light source

Claims (1)

[Claims] 1. A TAB tape carrier having a predetermined opening in a part of the film tape on which a conductive pattern is formed, a protective film having excellent foreign matter adhesion resistance on the surface of the conductive pattern above the opening. A tape carrier for TAB, characterized in that it is formed by coating or pasting.