JPH04287939A - Bonding tool - Google Patents

Abstract

PURPOSE:To bond satisfactorily even when bump heights and lead thicknesses are nut uniform for the hot press bonding of bumps with leads. CONSTITUTION:Many pieces of wire 10 which press leads are provided and an elastic body 11 is provided between each piece of the wire 10 and a shank 12. Since pressing force from the shank 12 is transmitted to the wire 10 through the elastic body 11, each lead is suitably pressed by the separate piece of wire 10.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bonding tool used in the process of thermocompression bonding a lead to a bump (protruding electrode) of a semiconductor chip or the like.

0002

2. Description of the Related Art FIG. 4 is a perspective view of a semiconductor chip mounted by tape automated bonding (TAB), and FIG. 5 is a sectional view taken along line V--V in FIG. In the figure, 1 is a semiconductor chip with an active function, and is placed in a window (both not shown) formed by cutting out the tape. 2 is a bump provided on the semiconductor chip 1, and 3 is a lead electrically and mechanically connected to the bump 2, which is extended from above the tape.

FIG. 6 is a side view showing a conventional bonding tool, where 4 is a tip that presses the lead 3, 5 is a shank that houses a heater (not shown), and the tip 4 is heated by the heater. . 6 is a heater insertion hole for setting this heater, and 7 is a shaft portion for attaching to a bonding device.

Next, a method for bonding the bump 2 and the lead 3 will be explained. FIG. 7 is a side view showing a bump-to-lead bonding process called inner lead bonding. First, as shown in FIG. 7(a), the bumps are aligned so that they are just below the ends of the leads 3. Next, when the tip 4 of the bonding tool heated to around 500°C is pressed against the lead 3 with constant pressure for a certain period of time as shown in FIG. As shown, both are thermocompressed together.

[0005]

[Problem to be solved by the invention] Conventional bonding
Since the tool is configured as described above, Fig. 8(a)
If the pressing surface 8 of the tip part 4 is curved as shown in FIG.
When the heights of the bumps 2 are uneven or the thickness of the leads 3 is uneven as shown in FIG. 2(b), the bumps 2 to be bonded
It is not possible to apply a pressing force to some of the leads 3, and a satisfactory bond cannot be obtained. In such a case, there is a problem that input/output of the semiconductor chip 1 is not performed normally, resulting in a defective product. The present invention was made to solve the above-mentioned problems, and an object of the present invention is to provide a bonding tool that can obtain satisfactory bonding even when bump heights and lead thicknesses are uneven.

[0006]

[Means for Solving the Problems] A bonding tool according to the present invention has a tip portion composed of a plurality of pressing pieces for pressing a lead, and an elastic body interposed between these pressing pieces and a shank portion. It is something.

[0007]

[Operation] The bonding tool of this invention can be used even when bump height or lead thickness is uneven.
A pressing force can be applied to each lead from separate pressing pieces through the elastic body.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view schematically showing a bonding tool according to an embodiment of the present invention.
6 and 7 are the same as in the case of FIG. 6, so their explanation will be omitted. 9 is the tip, and 10 is a pressing piece made of super hard and good heat conductive material such as tungsten carbide with a diameter of 50 μm.
The following short wire 11 is a spring-like elastic body, and the wire 10 and the elastic body 11 constitute the tip portion 9.

Reference numeral 12 designates a shank portion that incorporates a heating heater (not shown) and transmits a pressing force to the tip portion 9, and its outer edge portion 13 is extended downward in the figure to form a recess 14. There is. A large number of wires 10 are housed in the recess 14, and an elastic body 11 is interposed between each wire 10 and the bottom 15 of the recess 14, and the wire 10 is supported by the shank part 12 via the elastic body 11. ing.

Next, the operation will be explained. FIG. 2 is an explanatory diagram showing the operation of the bonding tool shown in FIG. 1, and shows a case where the heights of the bumps 2 are uneven. bump 2
It is assumed that the diameter of the lead 3 and the width of the lead 3 are 50 μm or more. In the figure, a downward pressing force is transmitted from the shank portion 12 to the wire 10 via the elastic body 11. The leads 3 are pressed onto the bumps 2 by the wires 10, but since the heights of the bumps 2 are uneven, the height positions of the leads 3 are also uneven. However, the tip part 9 that presses the lead 3 is composed of a large number of wires 10, and the wires 10 can be shifted from each other in the vertical direction in the figure, and the pressing force on each wire 10 is , it is possible to press each lead 3 with a pressure suitable for thermocompression bonding with the bump 2. The same operation also occurs when the thicknesses of the leads 3 are uneven.

[0011] It is preferable that the wire 10 is made of a carbide material so that its lifespan will not be shortened due to wear. Further, when the wire 10 is heated from the shank portion 12 as in this embodiment, it is preferable that the elastic body therebetween is also made of a material with good thermal conductivity. Furthermore, the reason why the diameter of the wire 10 is set to 50 μm or less is to enable each lead 3 to be appropriately pressed separately. The diameter of the wire 10 may be selected so that the dimensions are smaller than those.

FIG. 3 is a sectional view showing a bonding tool according to another embodiment of the present invention, in which 11 is a rubber-like elastic body. The elastic body 11 itself is integrally formed and connected to a large number of wires 10 on one surface thereof. Also in this embodiment, the respective leads 3 are pressed against each other by separate wires 10 by the pressing force transmitted through the elastic body 11, so that the same effect as in the case of FIG. 1 can be obtained.

[0013]

[Effects of the Invention] As described above, according to the present invention, since the tip portion is composed of a plurality of pressing pieces and an elastic body interposed between these pressing pieces and the shank portion, Pressing force can be applied to each lead from separate pressing pieces. Therefore, even if the height positions of the leads are uneven due to uneven bump heights, an appropriate pressing force can be applied to each lead, and a satisfactory bond between the leads and the bumps can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a bonding tool according to an embodiment of the invention.

FIG. 2 is an explanatory diagram showing the operation of the bonding tool of FIG. 1;

FIG. 3 is a cross-sectional view of a bonding tool according to another embodiment of the invention.

FIG. 4 is a perspective view of a mounted semiconductor chip.

FIG. 5 is a sectional view taken along line V-V in FIG. 4;

FIG. 6 is a side view of a conventional bonding tool.

FIG. 7 is a side view showing a step of bonding bumps and leads.

FIG. 8 is a cross-sectional view of a bonded portion for explaining the problems of bonding using a conventional bonding tool.

[Explanation of symbols]

2 Bump 3 Lead 9 Tip 10 Wire 11 Elastic body 12 Shank part

Claims (1)

[Claims] 1. A bonding tool that presses a lead onto a bump with a heated tip to bond them together by thermocompression, comprising: a plurality of pressing pieces made of a good heat conductive material and pressing the lead; A bonding tool characterized in that the tip portion is formed of an elastic body interposed between the pressing piece and a shank portion that supports the piece and transmits pressing force.