JPH043442A - Bump structure of tab inner lead and manufacture thereof - Google Patents

Abstract

PURPOSE:To enable a pump forming process to be simplified, obtain a sufficient junction strength even if the bump height deviates, and enable reliability to be enhanced by forming the bump where one part of a cylindrical chip is buried near a tip part of an inner lead. CONSTITUTION:A ribbon-shaped chip material 17 is punched by a punch 13 and a first die 15 and the punch 13 is returned to the original position. At this time, a penetration hole 20 whose diameter is equal to that of the first die 15 and that of a second dice 16 is formed at the ribbon-shaped chip material 17. Then, an inner lead 18 is placed between the first dice 15 and a second die 16, the punch 13 passes through the penetration hole 20 of the ribbon-shaped chip material 17 when the punch 13 is moved downward, the inner lead 18 is press-molded by the second die 16 and the punch 13, and a guide hole 21 whose diameter is equal to that of the punch 13 is formed. Then, the ribbon- shaped chip material 17 is moved and a position of the penetration hole 20 is moved. Finally, the ribbon-shaped chip material 17 is punched by the first die 15 and the punch 13, a cylindrical chip 23 is formed, and one part of the chip 23 is buried into the guide hole 21.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to TAB (Ta
The present invention relates to a bump structure formed at the tip of an inner lead of a tape carrier for (Automated Bonding) and a method of forming the bump by mechanical pressing.

[Prior Art] Generally, in order to mount a semiconductor element on a TAB tape carrier, it is necessary to form protrusions that serve as bumps on either the electrode portion of the semiconductor element or the inner lead end portion of the tape carrier. For example, there is a method for forming bumps on the electrode portion of a semiconductor device, as described in "IBM Journal, Vol. 8, 1964.
As described on page 102, there is a method of forming protrusions that will become bumps directly on the electrode portion by plating method, and a method of forming bumps directly on the electrode portion, and
tronic Packaging &Product
ion) J, December 1984 issue, pages 33-39, the pedestal method using etching technology, that is, by masking the part where the bump will be formed and half-etching the other inner lead parts. There is a method of forming protrusions with a height of 30 to 40 μm.

However, forming bumps using these methods not only requires expensive exposure equipment, plating equipment, and other equipment, but also requires a glue glazing process and an etching process for patterning, which makes the bump formation process difficult. It takes a long time.

Therefore, as described in Japanese Patent Publication No. Sho 64-10094, a method has been proposed in which a pedestal is manufactured at the tip of the inner lead using a mechanical press forming technique using a mold. In this method, as shown in FIG. 4(a), a tape carrier 34 in which a film 33 and an inner lead 18 are integrated is attached to a lower mold 32, and a convex portion 27 larger than the width of the inner lead 18 is inserted from above. Upper mold 2 with
8 is lowered, and as shown in FIGS. 4(B) and 4(C), a concave portion 30 is formed by pressing the convex portion 27 at the tip of the inner lead 18, and a pedestal 29, which will become a bump, is formed at the tip of the inner lead. This is a method of forming. Note that a notch 31 is provided in the width direction to allow the material of the recess 30 of the inner lead 18 pressed by the projection 27 of the upper mold 28 to escape.

[Problem to be solved by the invention]

However, the bumps formed on the tips of the inner leads using this type of pressing method have a solid cross-sectional shape obtained by molding the outer shape of the inner leads using a mold, so there is no connection between the semiconductor element and the bumps. This acts almost as a rigid body against the compressive load applied in the process of joining by thermocompression bonding. For this reason, if there are variations in the height of individual bumps, when bonding semiconductor elements and bumps all at once, it will not be possible to bond all the bumps uniformly, resulting in electrical connection failures. be. Therefore, in order to prevent connection failures, it is necessary to form bumps with high accuracy such that the height accuracy of the bumps is at least 0.5 μm or less, or to use a material that easily deforms at high temperatures as the bump material, and to Processing such as correcting the bump height is required when bonding the bumps. Figure 4(b).

In the conventional bump structure shown in (c), the bumps are formed directly on the inner lead by machining, so it is difficult to arbitrarily select the bump material. Therefore, when using the conventional method, it is required to form bumps with extremely high precision.

The purpose of the present invention is to solve these conventional problems, to simplify the bump formation process, to achieve sufficient bonding strength even with variations in bump height, and to achieve highly reliable bonding with semiconductor elements. An object of the present invention is to provide a bump structure for a TAB inner lead and a method for forming the same.

[Means for Solving the Problems] In order to achieve the above object, in the TAB inner lead bump structure according to the present invention, a TAB inner lead bump structure consisting of a combination of an inner lead of a TAB tape carrier and a chip is provided.
AB inner lead bump structure, wherein the inner lead of the TAB tape carrier has a guide hole near its tip, and the tip is made of a material that can be thermocompressed to the inner lead, and the tip is made of a material that can be thermocompressed to the inner lead. is made to protrude from the inner lead and is press-fitted into the guide hole of the inner lead.

Further, the bump structure of the TAB inner lead according to the present invention includes a punching process, a guide hole forming process, a chip forming process, and a press-fitting process, and the TAB inner lead and the chip are formed by combining the inner lead and the chip of the TAB tape carrier. A method for forming a bump structure on an inner lead, wherein the punching step includes arranging a ribbon-shaped chip material between a pair of punches and a first die, and using the punch and the first die to form a ribbon-shaped chip material. A through hole is formed by punching out a chip material, and the guide hole forming step includes arranging an inner lead below the first die, and placing a second die below the inner lead. The inner lead is press-formed by inserting the punch into the through hole punched in the ribbon-shaped chip material in the previous step and press-forming the inner lead using the punch and the second die. A guide hole is formed in the chip forming step, and in the chip forming step, an unpunched region of the ribbon-shaped chip material fed between the punch and the first die is formed between the punch and the first die. A columnar chip is formed by punching with It is press-fitted into the guide hole of the lead and its tip has a length that extends beyond the inner lead.The first step in forming the bump structure of the TAB inner lead is a punching process and a guide hole forming process.

The chip forming process and the press-fitting process are performed continuously, and from the next time onwards, the punching process is omitted and the guide hole forming process is performed.

It is obtained by a forming method that repeats a chip forming process and a press-fitting process.

[Function] The bump structure formed near the tip of the inner lead of the present invention has a structure in which a part of the columnar chip 23 is embedded in the guide hole 21, as shown in FIG.

The columnar chip 23 and the inner lead 18 are joined using frictional force. Therefore, when forming bumps, the chip 23
Although the bonding strength between the inner leads 18 and the electrodes 25 of the semiconductor element 24 is insufficient, as shown in FIG.
3 by thermocompression bonding, at the same time the guide hole 21
Since the chip 23 and the chip 23 can be bonded by thermocompression, sufficient strength can be achieved as a bump for the TAB inner lead.

In addition, in the bump structure of the present invention, the bump material can be arbitrarily selected, so even if there are variations in bump height,
It becomes possible to uniformly bond the semiconductor element and the inner lead.

In the TAB inner lead bump forming method according to the present invention, first, as shown in FIG. 2(a), the punch 13 and the first
The ribbon-shaped chip material 17 is punched out using the die 15, and the punch 13 is returned to its original position. At this time, the ribbon-shaped chip material 17 has a through hole 20 equal to the diameter of the punch 13.
is formed. Next, as shown in Figure 2 (b), the first
The inner lead 18 is placed between the second die 15 and the second die 16, and the punch 13 is moved downward. Figure 2 (
The punch 13 passes through the through hole 20 of the ribbon-shaped chip material 17 formed in step a), and the second die 16 and the punch 13 press-form the inner lead 18 to form a guide hole 21 having the same diameter as the punch 13. . Next, Figure 2 (
As shown in c), move the ribbon-shaped chip material 17,
The position of the through hole 20 is moved. Finally, as shown in FIG. 2, the ribbon-shaped chip material 17 is punched out using the first die 15 and the punch 13 to form a column-shaped chip 23, and a part of the chip 23 is embedded in the guide hole 21.

In the manner described above, a bump structure as shown in FIGS. 1(a) and 1(b) can be easily formed. Here, in the steps shown in FIG. There is no need for special positioning of the punch 21 and the punch 13, and the bump structure of the TAB inner lead as shown in FIG. 1 can be easily formed.

In the subsequent bump formation, a through hole 20 whose axis coincides with the punch 13 is formed in the ribbon-shaped chip material 17 by the step shown in FIG. 2 (cl), so the step shown in FIG. 2 (a) is unnecessary. Therefore, it is sufficient to repeat the steps from 6) to (company) in Fig. 2.

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

FIGS. 1A and 1B are a sectional view and a perspective view showing the bump structure of a TAB inner lead according to an embodiment of the present invention. FIGS. 2(a) to 2(d) are partial cross-sectional views showing, in order of steps, a method for forming bumps on a TAB inner lead according to an embodiment of the present invention.

As shown in FIGS. 2(a) to 2(d), a punch 13 having a tip diameter of 32 pm was inserted into the inner surface of a cylindrical punch holder 11 having an outer diameter of 6M, and the punch 13 was fixed to the upper end of the punch holder II. A part of the punch holder II has a spring structure 12 that expands and contracts in the vertical direction. Punch holder II
A slit-shaped ribbon guide 14 having a cross section of 1.2 mm in width and 50 pm in height into which the ribbon-shaped chip material 17 is inserted is provided at a part of the lower end. Ribbon guide 1
4, a first die 15 having a through die hole with a diameter of 35 μm and a depth of ]OOIIm is placed under the punch holder 11.
It was constructed to have an integrated structure. A second die 16 having a die hole with a diameter of 50 μm is placed below the first die 15, and between the first die 15 and the second die 16 an electrolytic copper foil is plated with gold. The inner leads 18 were arranged.

First, as shown in FIG. 2(a), a ribbon-shaped chip material 1
7 was punched out using the first die 15 and punch 13 to form a through hole 20 with a diameter of 35 pm in the ribbon-shaped chip material 17. The ribbon-shaped chip material 17 used here has a width of 1
The material was made of gold and had a thickness of 30 μm. Then the second
As shown in FIG. 18 is press-formed and has a diameter of 3
A guide hole 21 with a diameter of 5 pm and a depth of 20 pm was formed.

A spherical convex portion 2 with a diameter of 50 pm is provided on the back side of the guide hole 21.
2 was formed. Here, when the punch 13 is moved downward by the actuator 19, the punch 13 is moved downward as shown in FIG.
), only the inner leads 18 are press-molded without punching out the ribbon-shaped chip material 17, making it possible to form guide holes 21 as shown in FIG. 2(c). .

Next, as shown in FIG. 2(c), the ribbon-shaped chip material 17 was transferred and the position of the through hole 20 was moved.

Finally, as shown in FIG. 2(C), the punch 13 is moved downward by the actuator 19, and the ribbon-shaped chip material 1
7 is punched out using a punch 13 and a first die 15 to form a columnar chip 23 with a diameter of 35 pm and a height of 30 pm,
Guide hole 2 where a part of the bump 23 is formed as shown in FIG. 2 (c)
Embedded in 1. Chip 23 embedded in guide hole 21
The height from the top surface of the inner lead was about 25±lpm.

As described above, the chips 23 as shown in FIG. 1 are formed on the plurality of inner leads 18 of the TAB tape, and as shown in FIG. 150℃, pressure tool 2
6 (temperature: 500° C., pressure crab 60 gf/lead, bonding time 1 second), a good connection was achieved both in terms of strength (shear strength of 60 gf or more per lead) and electrically.

The reason why sufficient bonding strength was achieved with the bump structure shown in FIG. 1 as described above is that the chip 23 and the inner leads 18 could be bonded together by thermocompression at the same time. The bump height after thermocompression bonding was 20 μm, which was a sufficient height, and it was confirmed that it could be used as a bump for a TAB inner lead. Furthermore, despite the variation in bump height of ±lIIm, good connection was achieved because gold ribbon, which easily deforms at high temperatures, was used as the bump material.

[Effects of the Invention] As explained above, in the bump structure of the TAB inner lead of the present invention, even if there is a slight variation in the bump height,
This has the effect of allowing good mechanical and electrical connection between the bump and the electrode portion of the semiconductor element.

Furthermore, the TAB inner lead bump forming method of the present invention has the advantage that the bumps described above can be easily formed by a mechanical pressing method.

[Brief explanation of drawings]

Fig. 1 (ω is a cross-sectional view showing the bump structure of the TAB inner lead of the present invention, (b) is a perspective view thereof, and Figs. 2 (a) to (
Fig. 3 is a cross-sectional view showing a method for forming a bump on a TAB inner lead according to the present invention in the order of steps; ) is a sectional view illustrating the problem of the conventional method, (b) is a plan view of the same, and (c) is a side view of the same. 11... Punch holder 12... Spring 13.
... Punch 14 ... Ribbon guide 15
... First die 17 ... Ribbon-shaped chip material 19 ... Actuator 21 ... Guide hole 23 ... Columnar chip 25 ... AQ electrode

Claims (2)

[Claims] (1) A TAB inner lead bump structure consisting of a combination of an inner lead of a TAB tape carrier and a chip, wherein the inner lead of the TAB tape carrier has a guide hole near its tip. The chip is made of a material that can be thermocompression bonded to the inner lead, and the tip is press-fitted into the guide hole of the inner lead with its tip protruding from the inner lead.
B Inner lead bump structure. (2) A method for forming a bump structure of a TAB inner lead consisting of a combination of an inner lead and a chip of a TAB tape carrier, including a punching process, a guide hole forming process, a chip forming process, and a press-fitting process, In the punching step, a ribbon-shaped chip material is placed between a pair of punches and a first die, and the ribbon-shaped chip material is punched with the punch and the first die to form a through hole. The guide hole forming step includes arranging an inner lead below the first die, and arranging a second die below the inner lead so that its axis coincides with that of the first die. and inserting the punch into the through hole punched in the ribbon-shaped chip material in the previous step, and press-forming the inner lead using the punch and the second die to form a guide hole in the inner lead, In the chip forming step, the unpunched region of the ribbon-shaped chip material fed between the punch and the first die is punched using the punch and the first die to form a columnar chip. In the press-fitting step, the columnar chip processed in the chip-forming step is press-fitted into the guide hole of the inner lead, and the columnar chip is press-fitted into the guide hole of the inner lead and its tip end is press-fitted into the guide hole of the inner lead. The bump structure of the TAB inner lead is first formed by sequentially performing a punching process, a guide hole forming process, a chip forming process, and a press-fitting process. Thereafter, the method for forming a bump structure of a TAB inner lead is characterized in that the punching step is omitted and the guide hole forming step, chip forming step, and press fitting step are repeated.