JPH03214746A - Method of forming bump of tab inner lead - Google Patents

Abstract

PURPOSE:To simplify a bump forming process and facilitate quick traverse of inner leads which is necessary for high speed bump forming by a method wherein, after a hollow bump is formed on the inner lead by a press process, compressed air is supplied into the through hole of a die to remove the inner lead from the through hole of the die. CONSTITUTION:A part of an inner lead 11 is pushed into the through hole 18 of a die 17 by a punch 19 to form a hollow bump 13 on the inner lead 11. After the press process, compressed air is supplied into the through hole 18 of the die 17 to remove the inner lead 11 from the through hole 18 of the die 17. In this case, as the dome-shaped hollow bump 13 is formed near the tip of the inner lead 11 by a mechanical press method with the punch and the die, a bump forming process can be simplified. Moreover, a hollow bump structure is easier to be deformed by a compression force than a solid bump structure. With this constitution, even if the bumps have various heights, the bumps are so reformed as to have uniform heights by plastic deformation caused by a compression load applied at the time of thermocompression bonding.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is directed to a TAB (T
The present invention relates to a method for forming bumps on the tips of inner leads of Tape-4 Yaria (Autolated Bonding).

[Conventional technology]

Generally, in order to mount a semiconductor element on a TAB tape carrier, it is necessary to form a protrusion that becomes a bump on either the electrode part of the semiconductor element or the inner lead tip of the tape carrier. The method of forming bumps on the electrode portion of a semiconductor device includes, for example, [IBM Journal J Vol. 8 (1964) 1]
A method of forming protrusions that serve as bumps directly on the electrode portion by plating as described on page 02, "Proceedings of the 1985 IEICE Semiconductor and Materials Division National Conference, Lecture No. 2" (
The transfer bump method is a method of forming bumps on a glass substrate and then transferring the bumps to the electrode parts as described in ``Electronic Packaging'' (November 1985).
and production (ElectroniC Pa
ckaging & production) 3,
As described in the December issue of 1984, pages 33-39, the Bedestal method using etching technology, that is, masking the part where the bump will be formed and half-etching the other inner lead parts, is used to form a 30-40μ
There is a method of forming a protrusion with a height of m. However, forming bumps using these methods not only requires equipment such as expensive exposure equipment and plating equipment, but also requires a diagonal bump formation process that requires a phosphorography process and an etching process for patterning. There is a problem with the length of time.

To solve this problem, as described in Japanese Patent Publication No. Sho 64-10094, a method has been proposed in which a bump is manufactured at the tip of the inner lead using a mechanical press forming technique using a mold. This method is shown in Figure 2 (a) and (b).
, As shown in (c), a tape carrier in which the film 12 and the inner lead 11 are integrated is attached to the lower mold 24, and the upper mold 23 having a convex portion 25 larger than the width of the inner lead 11 is lowered from above. Inner lead 11
In this method, a protrusion (bump) 28 is formed at the tip of the holder by press working. Note that a notch 27 is provided in the width direction to allow the material of the recess 15 of the inner lead 11 pressed by the convex portion of the upper die 23 to escape.

[Problem to be solved by the invention]

The bumps formed on the tips of the inner leads by the above-mentioned press processing method are bumps with a solid cross-section formed by molding the outer shape of the inner leads using a mold, so the semiconductor element and the bumps are bonded together by thermocompression. It acts almost as a rigid body against the compressive load applied during the joining process. If there is variation in the height of the individual bumps, it is not possible to bond all the bumps uniformly when bonding the semiconductor element to the bumps, resulting in a problem of electrical connection failure. In order to prevent connection failures, the variation in bump height should be at least 0.5 μm.
It is necessary to satisfy the following conditions, and it is required to form bumps with extremely high precision. Further, there are problems such as the need to process the four parts of the inner lead to provide notches in advance.

SUMMARY OF THE INVENTION An object of the present invention is to solve these conventional problems and provide a method for forming bumps on TAB inner leads with a simple formation process.

[Means to solve the problem]

In order to achieve the above object, a method for forming a bump on a TAB inner lead according to the present invention is a method of forming a bump having a hollow structure by press working near the tip of the inner lead of a TAB tape carrier, the method comprising: A pressing process involves press-fitting a portion of the inner lead into the through-hole of the die using a punch to form a hollow structure bump on the inner lead. and a step of extracting it from the through hole.

[Effect]

According to the present invention, a bump having a dome-shaped hollow structure is formed near the tip of the inner lead by a mechanical pressing method using a punch and a die. This has the advantage that processing is unnecessary and the bump forming process can be greatly simplified. Moreover, since the bump structure is more easily deformed by compressive force than a solid structure, even if there is variation in the height of the bump, the bump will be plastically deformed by the compressive load during thermocompression bonding, resulting in a uniform height. can be corrected. Because of this, even if there are variations in bump height, it is expected that the hollow bumps can be uniformly brought into close contact with all the electrode parts of the semiconductor element, and good bonding can be achieved. In addition, when a bump is formed by pushing the inner lead into the die with a punch, the surface of the bump comes into close contact with the wall of the die through hole, which prevents the rapid movement of the inner lead, which is essential for high-speed continuous bump formation. This problem can be easily solved by blowing air onto the inner lead through the through hole.

〔Example〕

Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1(a) is a schematic diagram showing the bump forming method of the present invention,
(b). (C) is a plan view and a partially sectional side view showing an embodiment of the horizontal bump structure of the inner lead according to the present invention.

In the figure, 11 is an inner lead, 17 is a die with a through hole 78 formed at a location 6 that matches the bump forming position at the tip of the inch lead, and the inner lead 1
A tape carrier in which the tape carrier 1 and the plastic film 12 are integrated is mounted on the die 17. Attach the tape carrier to the die 17, and connect the through hole 18 and inner lead 11.
After performing the alignment, one punch is placed on the bump forming portion of the inner lead 11, and the punch 19 is lowered from above to cut a part of the inner lead 11 into the die 17.
The bumps 13 having a dome-like hollow structure are formed on the inner leads 11 by press-fitting them into the through holes 18 and mechanically pressing the tips of the inner leads. For example, a punch 19 with an outer diameter of 30 μm is pressed into a die 19 with an inner diameter of 50 μm by applying a load 16 of about 80 g, and the punch 19 has a width of 70 JJ.
m, 35 μm thick copper inner lead 11 (0 on the surface)
．． Bumps 13 are formed on the 5 μm Au plating process.

The hollow bump 13 formed at the center in the width direction of the lead tip has a hollow structure with a space, so the hollow bump 13 has the property of being easily deformed by compression from above, and the bump height An advantage of this is that even if there are variations, they can be corrected and bonded on the same plane. Furthermore, after the press working, the pipe 2 connected to the through hole 18 of the die 17 is
For example, high-pressure air or nitrogen scum 21 of 1 to 2 kg/unit is fed into the through hole 18 of the tie 17 through the 0, and the pressure is applied to the inner lead 11 that has been compressed into the through hole 18. 11 from the die 17. Therefore, the inner lead 11 can be easily removed from the die 17 after press working.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to form a TAB inner lead bump structure with a simple formation process, low manufacturing cost, and high productivity.

Furthermore, since gas pressure is applied to the inner lead after pressing and the inner lead is forcibly extracted from the through hole of the tie, the inner lead can be rapidly fed, which is necessary for high-speed continuous bump formation.

[Brief explanation of drawings]

FIG. 1 fa) is a schematic diagram showing the bump forming method of the present invention,
([]) is the bump 'WI of the inner lead according to the present invention.
(C) is a partially sectional side view, and Figures 2 (a), (b), and (c) show a mechanical press forming process using a conventional mold. It is a figure which shows the bump formation method used. 11... Inner lead 12... Film 13
...Hollow bump 15...Lead recess 16.
...Load 17...Tice 18...Through hole 19...Punch 20...Pipe
21...High pressure air 23...Upper mold
24... Lower mold 25... Convex part 2
7...Lead notch 28...Bump special board "Out 1qI'i person ["Kidenki Co., Ltd. ji company representative]
Attorney Patent Attorney Kanno
Junior High 9 (α) Fig. 1 (b) (ri Fig. 1 (α) Fig. 2 (b) (C)

Claims (1)

[Claims] (1) A method of forming a hollow structure bump near the tip of the inner lead of a TAB tape carrier by press working, in which a part of the inner lead is press-fitted into a through hole of a die with a punch, and the inner lead is attached to the inner lead. A TAB inner lead bump characterized by comprising a pressing step of forming a bump with a hollow structure, and a step of extracting the inner lead from the through hole of the die by pumping gas into the through hole of the die after the pressing step. Formation method.