JPH03211847A - Device for forming bump of tab inner lead - Google Patents

Abstract

PURPOSE:To make it possible to so form a bump easily as to obtain the bonding to a semiconductor device with a satisfactory joining strength even when there are variations in the heights of the bumps and give no deformation to an inner lead, by using a punch for forming the bump on the inner lead. CONSTITUTION:A bump of a hollow structure is formed, using a punch whose diameter is increased upward from the lowest end of a protruding part 12 of the punch's head as a trapezoidal punch 11 of an inverted circular cone shape. That is, the center of the protruding part 12 of the punch's head is made to coincide with the center of a die's hole 15 of a die 16. Thereafter, the punch 11 is pushed into an inner lead 13 installed on the die 16, and a hollow bump 14 is formed at the head of the inner lead 13. After the hollow bump 14 is formed, when the punch 11 is detached from the inner lead 13, the punch 11 can be detached from it, giving scarcely any deformation to it, and the bump 14 to the hollow structure can be formed. Thereby, even when there are variations in the heights of the bumps, the bump 14 of the hollow structure which can attain the bonding to a semiconductor element with a satisfactory bonding strength can be formed easily, giving no deformation to the inner lead 13.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to TAB (Tap) used for mounting semiconductor devices.
The present invention relates to a bump forming device that forms bumps on the inner lead tips of a tape carrier for Automated [3 onding] by mechanical press processing.

[Prior Art] 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. Examples of methods for forming bumps on electrode portions of semiconductor devices include:

[IB (I Journal)
) J Vol. 8 (1964) p. 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 protrusions that will become bumps directly on the electrode portions, as described in [Electronic Packaging and Production ([1cctronic l'ack
The pedestal method using an etching technique, that is, the part where the bump is to be formed, is masked and the other inner There is a method of forming protrusions with a height of 30 to 40 pm by half-etching the lead part, or
Communication Society of Japan 1'-Conductor/Materials Division National Conference Proceedings, 11
A transfer bump method has been used in which bumps are formed on a glass substrate and then transferred to electrode portions as described in 1985+2J (1985++B).

However, forming bumps using these methods not only requires equipment such as expensive exposure equipment and plating equipment, but also requires high material costs and a process of laminating and etching for patterning. Therefore, there is a problem that the bump formation becomes long.

For this reason, as described in Japanese Patent Publication No. 64-10094, a method has been proposed in which the pedestal 19 is manufactured by forming a recess 18 at the tip of the inner lead using mechanical press forming technology using a mold. (See Figure 6).

In this method, a tape carrier in which a film and an inner lead are integrated is attached to the lower mold, and a mold 8 having a protrusion larger than the width of the inner lead is lowered from one side to the tip of the inner lead. In this method, the four parts 18 are formed by pressing, and a pedestal 19, which becomes a bump, is formed at the tip of the inner lead. Note that notches are provided in the width direction to allow the material of the four parts 18 of the inner lead that has been pressed down by the "-" shaped convex portion to escape.

[Problems to be Solved by the Invention] However, the bumps formed on the tips of the inner leads by such a press working method have a solid (structure) Because of the bumps, they act almost as a rigid body against the compressive load applied during the process of bonding semiconductor elements and bumps by thermocompression bonding.For this reason, if there are variations in the height of individual bumps, it may be difficult to bond the semiconductor element and bumps properly. When bonding all the bumps uniformly, there is a problem that electrical connection defects occur.In order to prevent connection defects, it is necessary to reduce the variation in the height of the bumps by at least 0.5 pm. It is necessary to do the following, and it is required to form the bumps with extremely high precision.Furthermore, there are problems such as the need to process the recesses of the inner leads to provide notches in advance.

The purpose of the present invention is to solve such conventional problems, and to provide a bump with a hollow structure that can achieve bonding with a semiconductor element with sufficient bonding strength even if there are variations in bump height, and which causes deformation in the inner lead. An object of the present invention is to provide an apparatus for forming bumps on TAB inner leads, which can be easily formed without causing any damage.

[Means for solving the problem] In order to achieve the purpose stated in 011, TA [
(In the inner lead bump forming device, TA[
A device having a punch and die set for forming a bump by mechanical pressing near the tip of the inner lead of a tape carrier for 3, wherein the punch presses the tip of the punch from the die hole of the die. It is formed into an inverted truncated cone shape that expands in diameter in the direction of the axis from which it is removed.

[Function] As a bump structure that enables good connection even if there is variation in bump height, the bump structure is formed into a dome shape smaller than the width of the inner lead by mechanical pressing using a punch and die. As shown in FIG. 2, a bump 14 having a hollow structure is considered. Hollow structure bumps have the advantage of not requiring any pre-processing for bump formation, which greatly simplifies the bump formation process.Furthermore, the bump structure is more easily deformed under compressive force than solid structures, making it easier to form bumps. Even if there is variation in height, the bump can be plastically deformed by the compressive load during thermocompression bonding and can be corrected to a uniform height.

Therefore, even if there are variations in bump height, the hollow bumps 14 can be brought into uniform contact with all the electrode parts of the semiconductor element.

However, as shown in FIGS. 3(a) to 3(c), the hollow bump 14 is punched with a punch II! 6, the punch 11 is in close contact with the inner surface of the hollow bump 14 during the removal process of the punch 11 shown in FIG. Due to the frictional force acting between the inner surfaces of 14, the inner lead 13 is punched 1! This causes a problem in that the inner lead 13 moves together with the inner lead 13, causing the inner lead 13 to be deformed as shown in FIG. If the inner lead 13 is deformed, the electrode portion of the semiconductor element and the bump 14 cannot be bonded well, so it is necessary to easily remove the punch 11 without deforming the inner lead 13.

The punch 11 commonly used in the past is shown in Fig. 4 (b).
As shown in Punch I! Convex part at the tip! 2 is cylindrical (constant straight tF,), the punch l! Even if the convex portion 12 moves slightly relative to the inner surface of the hollow bump 14, the punch I
The convex portion 12 of I was still in close contact with the inner surface of the hollow bump 14, and the punch II could not be easily removed. For this reason, there was a problem in that the inner lead I3 was left with a large deformation l as shown in FIG. 5 due to the detachment of the punch II.

On the other hand, in the bump forming punch 11 of the present invention as shown in FIG. Since it is formed into a shape, as shown in Fig. 4 (, -,
), as long as the tip of the protrusion 12 of the punch 11 moves relative to the hollow bump 14 in the negative direction by 4'fr, the tip of the punch 11 separates from the inner surface of the hollow bump 14, and the punch 11 and the bump 14 A gap I7 is created between the inner lead I3 and the inner lead I3, so that the punch 11 can be easily removed from the inner lead I3. Therefore, the bump 14 having a hollow structure can be formed without substantially deforming the inner lead 13.

[Example 1] Hereinafter, an example of the present invention will be described in detail using the N side.

FIG. 1 is a side view showing a bump forming punch of the present invention, FIG. 2 is a cross-sectional view showing a hollow structure bump formed according to an embodiment of the present invention, and FIGS. 3(a) to (c)
1A and 1B are cross-sectional views showing step-by-step a bump forming method according to an embodiment of the present invention.

As shown in Fig. 1, as an inverted truncated conical punch l,
Using a punch 11 in which the diameter φd of the lowermost end of the convex portion 12 at the tip of the punch is 30 μm, and the angle O formed between the side walls that widen in diameter upward from the lowermost end is 60 degrees, FIGS.
A bump having a hollow structure was formed by the process shown in c). The die 16 used to form the hollow bump 14 is
It has a dish-shaped die hole 15 with a hole diameter of 50 pm and a depth of 30 μm, and the inner lead 13 has a width of 70 pm.
A pn+ material with a thickness of 35 pm and a pitch of 140 pm was used.

First, as shown in FIG. 3(,), align the convex portion 12 at the tip of the punch 11 with the center of the die hole 15 of the die 16,
Thereafter, as shown in FIG. 3 (G), the punch 11 is pushed into the inner lead I3 mounted on the die 16 (the amount of pushing of the punch 1 into the inner lead is about 30 μm),
A hollow bump 14 was formed at the tip of the inner lead 13. After forming the hollow bump 14, when the punch 11 is removed as shown in FIG. 3(c), the inner lead 13 is removed.
The punch 11 can be removed with almost no deformation to the bump 14, which has a hollow structure as shown in FIG.
was able to form. Here, the amount of deformation I of the inner lead 13 shown in FIG. 5 was within 111+11. Furthermore, the height variation of the formed hollow bumps 14 was approximately 30±1 μm.

The hollow bump 14 of the inner lead 13 of the TAB tape formed by the method described in -1- is bonded to the AQ electrode part of the semiconductor element using a low-temperature bonding method (element heating temperature: 275°C,
Pressure tool temperature: 450°C9 pressure 60gf/lead.

As a result of bonding (1 second), the height of the hollow bump 14, which had a variation of ±Ipm, was corrected, a good connection was achieved both in terms of strength and electrically, and it was confirmed that it could be fully used as a bump for the inner lead. .

For comparison, hollow bumps 14 were similarly formed using a conventional punch 11 having a cylindrical protrusion 111112 as shown in FIG. 4(b). A large deformation occurred in the inner lead 13 (the amount of deformation was 30 to 50 μm), and a good connection to the Aρff1 pole portion of the semiconductor element could not be made.

〔Effect of the invention〕

As explained above, by using the punch for forming bumps on TAB inner leads of the present invention, a hollow hole can be formed that can achieve bonding with a semiconductor element with sufficient bonding strength even if there are variations in bump height. This has the effect that a structural bump can be easily formed without causing deformation of the inner lead.

[Brief explanation of drawings]

FIG. 1 is a side view showing a bump forming punch according to the present invention, FIG. 2 is a sectional view showing a hollow bump formed according to an embodiment of the present invention, and FIGS. 4(a) is a sectional view showing the process of removing the punch when the bump forming punch of the present invention is used, and FIG. 4(b) is a sectional view showing the process of bump formation using the conventional punch. 5 is a sectional view showing the deformation of the inner lead caused by the removal of the punch when the punch is used, and FIG. 6 is a side view showing the conventional solid bump structure. be. 11... Punch I2... Convex portion 13...
・Inner lead 14...Hollow bump 5...Die hole 16...Dice 7...Gap
18... recess 9... pedestal

Claims (1)

[Claims] (1) A device having a punch and die set for forming a bump near the tip of the inner lead of a TAB tape carrier by mechanical pressing, the punch punching the tip of the punch into the die hole of the die. A bump forming device for a TAB inner lead, characterized in that it is formed into an inverted truncated conical shape whose diameter increases in the axial direction from which it is detached.