JPH03214747A - Apparatus for forming bump of tab inner lead - Google Patents

Abstract

PURPOSE:To avoid bump forming failures caused by the offset of axes and improve the yield of bump forming on an inner lead by a method wherein a part of the inner lead is pushed into the through hole of a die to form a hollow bump and a means which monitors the relative position between the position of a punch and the through hole of the die optically is provided. CONSTITUTION:A die 17 having a through hole 18, a punch 19 which pushes a part of an inner lead 11 into the through hole 18 of the die 17 to form a hollow bump 13 and an optical means which monitors the relative position between the position of the punch 19 and the through hole 18 of the die 17 are provided. In this case, a dome-shaped hollow bump 13 is formed near the tip of the inner lead 11 by a mechanical press method with the punch 19 and the die 17 and, further, the accurate position of the die 17 is monitored through an image fiber 20 provided in the through hole 18 of the die 17. With this constitution, a bump forming process can be substantially simplified and defects caused by offset between the punch 19 axis and the die 18 axis can be avoided, so that the yield can be improved.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to TAB (Tap) used for mounting semiconductor devices.
[Conventional technology] Generally speaking, in order to mount a semiconductor device on a tape carrier for TAB, bumps are formed on the electrode portion of the semiconductor device or the inner lead of the tape carrier. It is necessary to form a protrusion to serve as a bump on one of the tips. For the method of forming bumps on the electrodes of semiconductor devices, for example, "IBM Journal J Volume 8 (1964)
A method of forming protrusions that serve as bumps directly on the electrode portion by plating as described on page 102, "Proceedings of the 1985 IEICE Semiconductor and Materials Division National Conference, Lecture No. 2"
(November 1985), the transfer bump method involves forming bumps on a glass substrate and then transferring the bumps to the electrodes, as well as the "Electronic Packaging and Production (Electronic Packaging and Production)" method.
Packaoinq & Production)
J, December 1984 issue, 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. ~
There is a method of forming protrusions with a height of 40 μm. but,
Forming bumps using these methods not only requires equipment such as expensive exposure equipment and plating equipment, but also requires a patterning lithography process and etching process, which lengthens the bump formation process. There is a problem.

Therefore, 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). (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 made by molding the outer shape of the inner leads using a mold, and then forming the bumps, which have a solid cross-sectional shape, by thermocompression bonding the semiconductor element and the bumps. It acts almost as a body against the compressive load applied in the joining process. For this reason, if there are variations in the height of individual bumps, there is a problem that when bonding the bumps to the semiconductor element, it is difficult to bond all the bumps uniformly, and electrical connection failures occur. 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 other problems, such as the need to process the recessed portion of the inner lead to provide a notch in advance.

SUMMARY OF THE INVENTION An object of the present invention is to provide a TAB inner lead bang forming apparatus that solves these conventional problems and has a simple forming process.

[Means to solve the problem]

In order to achieve the above object, the TAB inner lead bump forming apparatus according to the present invention is an apparatus for forming a hollow bump by press working near the tip of the inner lead of a TAB tape carrier, and includes a through hole. a punch that presses down a part of the inner lead into the through hole of the die to form a hollow bump; and an optical means that optically observes the position of the punch with respect to the through hole of the die. It is.

[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, and a pre-forming process for forming the bump, which is necessary in conventional press processing, is performed. 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 bump height, the bump will be plastically deformed by the compressive load during thermocompression bonding and will be corrected to a uniform height. I can do it. Because of this, it is expected that even if there is variation in the bump height, the hollow bump can be brought into close contact with all the electrode parts of the semiconductor element uniformly and good bonding can be achieved. Furthermore, since the accurate position of the die can be monitored by an image fiber installed in the through hole of the die, failures in forming bumps due to misalignment of the punch and die axes are eliminated, and the yield of forming bumps on inner leads can be improved.

〔Example〕

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

FIG. 1(a) is a schematic diagram showing a bump forming apparatus of the present invention,
(1:l) and (C) are a plan view and a partially sectional side view showing an embodiment of the bump structure of the inner lead according to the present invention. Through hole 1 is placed in a location that matches the bump formation position.
A tape carrier in which an inner lead 11 and a plastic film 12 are integrated is mounted on the die 17 on which the number 8 is formed. In addition, one end of the image fiber 20 is inserted into the through hole 18 of the six dies 17 from below to a height that does not interfere with press working, and the other end of the image fiber 2o is inserted outside the through hole 18. A 1'V camera 21 is connected to the end thereof, and a TV monitor 22 is connected to the TV camera 21. Here, the image fiber 20
The center of the field of view of the image fiber 20 is set to correspond to the center of the through hole 18 of the die 17, and the field of view of the image fiber 20 is set to a size approximately corresponding to the opening area of the through hole 18 of the die 17. When the image of the punch 19 relative to the through hole 18 is partially missing from the field of view of the image fiber 20, it is detected that the punch 19 and the die 17 are misaligned. Before attaching the tape carrier to the die 17, the through holes 18 of the die 17 and the inner leads 11 are aligned. An image of the punch 19 guided by an image fiber 20 installed in the through hole 18 is formed on a TV camera 21 and observed on a TV monitor 22. Therefore, as shown in the figure, positioning can be easily performed on the TV monitor 22 by moving the punch 19 or the die 17 so that the magnification of the punch 19 @19' is located approximately at the center of the field of view of the image fiber. It is possible to improve the yield of bump formation and to greatly reduce the number of alignment steps.

After the above-described alignment, the inner lead 11 is mounted on the die 17, and the punch 19 is lowered from above to mechanically press the tip of the inner lead to form a bump. For example, a load of about 80 g is applied to a punch 19 with an outer diameter of 30 μm, and a punch 19 with a width of 70 μm and a thickness of 3
5μm copper inner lead 11 (0.5μm Au plating on the surface, surface roughness is RHAX = 0.5μm)
) to form bumps 13. 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.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to form bumps on TAB inner leads with a simple formation process, low manufacturing cost, and high productivity. Furthermore, since the axis misalignment of the punch and die is output as an image using an image fiber, it is possible to eliminate the occurrence of defective products due to axis misalignment and improve yield.

[Brief explanation of drawings]

FIG. 1(a) is a schematic diagram showing a bump forming apparatus of the present invention,
(b) is a plan view showing an embodiment of the bump structure of the inner lead according to the present invention, (C) is a partially sectional side view, and FIGS. 2(a), (b), and (c) are conventional molds. FIG. 3 is a diagram illustrating a bump forming method using a mechanical press molding technique.

Claims (1)

[Claims] (1) A device that forms a hollow structure bump near the tip of the inner lead of a TAB tape carrier by press processing, which includes a die equipped with a through hole and a part of the inner lead pressed into the through hole of the die. A bump forming device for a TAB inner lead, characterized in that it has a punch for forming a bump with a hollow structure, and an optical means for optically observing the position of the punch with respect to the through hole of the die.