JPH043441A - Method and device for forming bump of tab inner lead - Google Patents

Abstract

PURPOSE:To enable a bump forming process to be simplified, obtain a sufficient junction strength even if the bump height deviates, and enable reliability to be enhanced by burying a stopper material at one part of an inner surface of the bump with a hollow structure which is press molded by one set of punch and die. CONSTITUTION:A ribbon-shaped stopper material 17 is punched by a punch 13 and a combination of a dice hole 15a of a first dice 15 and a stopper material for reinforcement 20 is formed. The punch 13 press-machines an inner lead 18 through the stopper material 20, a dome-shaped hollow-structured bum is formed at the inner lead 18 by press of the punch 13, and the stopper material 20 operates as one part of the punch 13 to inject the stopper material 20 into a guide hole of the bump. The punch 13 for protruding the die hole 15a is lowered toward a die 16 and the inner lead 18 is press-molded by a combination of the punch 13 and a die hole 16a of the die 16, thus forming a hollow- structured bump where the stopper material 20 is buried and achieving a uniform and improved connection to all electrode parts of the semiconductor element.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to TAB (Ta
The present invention relates to a method and a bump forming apparatus for forming a rebump on the tip of an inner lead of a tape carrier for (Automated Bonding) by mechanical pressing.

[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 portions of semiconductor devices includes, for example, [IBM Journal, Vol. 8 (1964), 1]
As described on page 02, there is a method of forming bumps directly on the electrode part by plating method,
Packaging and “Production” (Elect
ronic Packaging & Product
On) J, December 1984 issue, pages 33-39, the pedestal method uses etching technology, that is, the part where the bump will be formed is masked and the other inner lead parts are half-etched. Accordingly, 3
There is a method of forming protrusions with a height of 0 to 40 μm. However, forming bumps using these methods not only requires equipment such as expensive exposure equipment and plating equipment;
Since a bonding process and an etching process are required for patterning, there are problems such as a long time spent in the bump forming process.

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. 5(a), a tape carrier 26 in which a film 25 and an inner lead 18 are integrated is attached to a lower die 24, and a convex portion 27 larger than the width of the inner lead 18 is formed from above. Upper mold 28
In this method, the tip of the inner lead 18 is pressed by the convex portion 27 by lowering the inner lead 18, and a pedestal 29 serving as a bump is formed at the tip of the inner lead. In addition, upper mold 2
A cutout 31 is provided in the width direction to allow the material of the recess 30 of the inner lead 18 pressed by the protrusion 27 of No. 8 to escape.

[Problem to be solved by the invention]

However, the bumps formed on the tips of the inner leads using this press processing method have a solid cross-sectional shape obtained by molding the outer part of the inner leads using a mold, so it is difficult to connect the semiconductor element and the bumps. The material acts as a rigid body against the compressive load applied during the thermocompression bonding process.

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. In order to prevent connection failures, the variation in bump height must be at least 0.5μ.
m or less, and it is required to form bumps with extremely high precision. Further, there is a problem in that the recessed portion of the inner lead requires processing to provide a notch in advance.

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 forming method and a bump forming apparatus for TAB inner leads.

[Means for Solving the Problems] In order to achieve the above object, the TAB inner lead bump forming method according to the present invention includes a stopper material punching step, a transfer step, and a stopper material embedding/bump forming step. A method for forming a bump on a TAB inner lead, wherein the stopper material punching step includes punching reinforcing stopper material from a ribbon-shaped stopper material fed between a pair of first dies and a punch. The transferring step is a step of pressing down a through hole formed in the ribbon-shaped stopper material with a protruding punch to push out the reinforcing stopper material toward a second die, and the stopper material embedding - The bump forming step is a step of rolling down the inner lead supported by the second die through the reinforcing stopper material with the punch, and forming a bump with a dome-shaped hollow structure on the inner lead by rolling down with the punch. Then, a stopper material for reinforcing the sag is press-fitted into the bump of the formed dome-shaped hollow structure and embedded therein.

Further, in the TAB inner lead bump forming method according to the present invention, the TAB inner lead bump forming method includes a through hole forming step, a bump forming step, a stopper material punching step, and a stopper material transfer/embedding step. The through hole forming step is a step of punching a through hole in a ribbon-shaped stopper material fed between a pair of first dies and a punch, and the bump forming step is a step of further pressing down the inner lead supported by the second die with a punch projecting through the through hole formed in the ribbon-shaped stopper material to form a bump having a dome-shaped hollow structure on the inner lead; The stopper material forming step is a step of punching the unpunched region of the ribbon-shaped stopper material fed between the punch and the first die to form a reinforcing stopper material. Yes, the stopper material transfer/embedding step includes extruding the reinforcing stopper material toward the second die with the punch that protrudes through the ribbon-shaped stopper material, and extruding the reinforcing stopper material toward the second die. The punched reinforcing stopper material is press-fitted into the bump of the dome-shaped hollow structure of the inner lead and embedded. First, when forming the bump of the TAB inner lead, there are a through hole forming step and a bump forming step. .

The stopper material punching process and the stopper material transfer/embedding process are performed continuously, and from the next time onward, the bump forming process, the stopper material punching process, and the stopper material transfer/embedding process are repeated.

Further, in the TAB inner lead bump forming apparatus according to the present invention, the TAB inner lead bump forming apparatus has first and second dies and a single punch shared by both the dies, The first die is
The second die supports a ribbon-shaped stopper material, and includes a die hole penetrating vertically through which the ribbon-shaped stopper material is punched by pressing down with the punch, and the second die supports an inner lead. , the inner lead is provided with a die hole that forms a bump having a dome-shaped hollow structure when pressed by the punch; The first die is arranged in the upper stage and the second die is arranged in the lower stage so as to coincide with each other, and the punch passes through the die hole of the first die and the second die.
It has a movement stroke that reaches the die hole of the die.

[Function] The bumps formed on the inner leads by the mechanical pressing method using a punch and die are hollow-structured bumps formed in a dome shape that is at least smaller than the width of the leads, as shown in Fig. 4 (6). It is 21. Hollow structure bumps do not require pre-processing for bump formation, and have the advantage of greatly simplifying the bump formation process.Moreover, compared to solid structures, the bump structure deforms more easily under compressive force, making it easier to form bumps. Even if there are variations in the height of the bumps, the bumps are plastically deformed by the compressive load during thermocompression bonding and can be corrected to a uniform height.

However, in the bump 21 having a hollow structure as shown in FIG.
Since the bump strength is insufficient, the bump is easily deformed by the load during thermocompression bonding, making it difficult to maintain a sufficient bump height after connection. In order to ensure a sufficient bump height, as shown in FIGS. 4(a) and 4(c), a stopper material 20 is embedded in a part of the inner surface of the hollow structure bump 21 to reinforce the mechanical strength of the bump. It is necessary to do so. A hollow bump structure in which such a stopper material 20 is embedded has a characteristic that it is more easily deformed than a solid structure bump, and even if there is variation in bump height, the bump height can be easily corrected during thermocompression bonding. It becomes possible to do so.

Moreover, since the mechanical strength is increased compared to the hollow structure bump shown in FIG. 4(b), a sufficient bump height can be ensured even during thermocompression bonding. The bump height after bonding can be adjusted by changing the volume of the stopper material and the high temperature strength at the bonding temperature.

For this reason, in a hollow structure bump filled with stopper material, all parts of the semiconductor device can be removed. It can be brought into uniform contact with the pole parts, and a good connection can be made both mechanically and electrically.

As shown in FIG. 1, in the TAB inner lead bump forming apparatus of the present invention, a punch 13 is supported by a cylindrical punch holder 11 having a ring-shaped cross section and at least a portion of which is made of an elastic body 12. is punch holder 11
It is fixed to the upper stage holder part 11a. A slit-shaped (square hole) ribbon guide 1 is attached to the cylindrical punch holder +1.
4 is provided, and a ribbon-like stopper material 17 is inserted into the ribbon guide 14. Further, a first die 15 supported by the lower holder portion 11b of the punch holder +1 is arranged below the ribbon guide 14, and a second die 16 is arranged below the first die 15.

The first die 15 is provided with a vertically penetrating die hole +5a for punching the ribbon-shaped stopper material 17 by pressing down with the punch 13, and the second die 16 is provided with an inner lead 18 by pressing down with the chip 13. is provided with a die hole 16a for forming a dome-shaped hollow structure bump 21,
The dice 15 and the dice 16 are arranged such that the first die 15 is arranged in the upper stage and the second die 16 is arranged in the lower stage, with the axes of the die holes 15a and 16a of both coins aligned. . The punch 13 is the die hole 1 of the die 15.
5a and reaches the die hole 16a of the die 16.

When the punch 13 is moved downward, the punch 13 becomes integral with the punch holder 11 and moves downward. first die 1
5 contacts the inner lead 18, the punch holder 1
1 is contracted and deformed, only the punch 13 moves downward, and the ribbon-shaped stopper material 17 can be punched out by the punch 13 and the first die 15.

Further, when the punch I3 protruding from the through hole formed in the stopper material 17 is moved downward, the inner lead 18 can be press-molded by the punch 13 and the second die 16.

In the TAB inner lead bump forming method of the present invention,
As shown in FIG. 2(a), the punch 13 and the first die 1
A ribbon-shaped stopper material 17 is inserted between the
An inner lead 18 is arranged between the first die 15 and the second die 16. First, as shown in FIG. 2(B), the punch 13 and the die hole 15a of the first die 15 are
The ribbon-shaped stopper material 17 is punched out to form a reinforcing stopper material 20. Furthermore, Figure 2 (
As shown in c), the punch 1 protrudes through the die hole 15a.
3 toward the die 16 continuously with the operation shown in FIG. Stopper material 2 as shown in a)
It is possible to form a bump 21 having a hollow structure in which zero is embedded. Here, in FIG. 2(c), the punch j3 presses the inner lead 18 through the stopper material 20, and the bump 2I having a dome-shaped hollow structure is formed on the inner lead 18 by pressing down with the punch 13. The stopper material 20 acts as part of the punch 13 in order to press the bump 20 into the guide hole of the bump 21 .

In the manner described above, a bump 21 having a hollow structure in which the stopper material 20 is embedded as shown in FIG. 4(a) can be formed.

In addition, in the TAB inner lead bump forming method of the present invention, as shown in FIG. return. At this time, a through hole 22 having the same diameter as the punch 13 is formed in the ribbon-shaped stopper material j7. Next, as shown in FIG. 3(B), the inner lead 18 is placed between the first die 15 and the second die 16, and the punch 13 is moved downward.

The through hole 22 of the ribbon-shaped stopper material 17 and the die hole +5a of the die 15 formed in FIG. 3(a) are punched with a punch 1.
3 passes through, and the inner lead 18 is press-molded by the second die 16 and the punch 13 to form a hollow bump 21 as shown in FIG. 4(b). At this time, a guide hole 23 having the same diameter as the punch 13 is formed on the back surface of the hollow bump 21 .

Next, as shown in FIG. 3(c), the ribbon-shaped stopper material 17 is moved to move the position of the through hole 22. Finally, as shown in FIG. 3(d), the ribbon-shaped stopper material 17 is punched out using the first die 15 and the punch 13 to form a column-shaped reinforcing stopper material 20.
Press in and embed.

In the manner described above, it is possible to form a bump 21 having a hollow structure in which the stopper material 20 is embedded, as shown in the fourth [J(c)]. Here, in the steps shown in FIGS. 3(b) to 3(d), the axes of the punch 13, the die hole 16a of the second die 16, and the guide hole 23 are always aligned, so the stopper material 20 is guided. When filling the hole 23, there is no need to perform special positioning between the guide hole 23 and the punch 13, and it is possible to easily form the bump 21 having a hollow structure as shown in FIG. 4(c).

Note that in the subsequent bump formation, a through hole whose axis coincides with the punch 13 is formed in the ribbon-shaped stopper material 17 by the step shown in FIG. 3(d), so the step shown in FIG. 3(a) is unnecessary. , by repeating the steps in FIGS. 3(c) to 3(c).

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

FIG. 1 is a cross-sectional view showing a TAB inner lead bump forming apparatus according to an embodiment of the present invention, and FIGS. 2(a) to (c) show a TAB inner lead bump forming method according to Embodiment 1 of the present invention. Cross-sectional views shown in the order of steps, FIGS. 3(a) to (cl.
) is a cross-sectional view showing the process order of a method for forming bumps on a TAB inner lead according to Example 2 of the present invention.

(Example 1) First, Example 1 of the present invention will be described in detail with reference to the drawings. As shown in FIG. 1, a punch 13 with a tip diameter of 30 μm is inserted into the inner surface of a cylindrical punch holder 11 with an outer diameter of about 6, and the upper holder portion of the punch holder II is
A punch 13 was fixed to a. The upper holder part 11a and the lower holder part 11b of the punch holder 11 are connected by an elastic body (spring structure) +2 that expands and contracts in the vertical direction. The lower holder part 11b of the punch holder II has a width of 1.2 mm in which a ribbon-shaped stopper material ]7 is inserted into a part of its lower end.
, a slit-shaped ribbon guide 14 having a cross section with a height of 50 μm is provided.

Below the ribbon guide 14, a diameter of 35 μm and a depth of l1 are provided.
It has a first die I5 having a die hole 15a of 00p, and the lower holder portion 11b of the punch holder 11 and the first die 15 are configured to have an integral structure. A second die 16 having a die hole 16a with a diameter of 50 pm was arranged below the first die 15, and an inner lead 18 was arranged between the first die 15 and the second die 16. The axes of the through die hole 15a of the first die 15 and the die hole 16a of the second die 16 are aligned, and the first die I5 and the second die 16 are connected to the punch 1.
3, they are arranged in two stages, upper and lower.

Bumps were formed using the TAB inner lead bump forming apparatus shown in FIG. 1 described above. First, Figure 2 (a
) to (C), embodiments of the present invention will be described in detail. As shown in FIG. 2(a), the ribbon guide 1
A ribbon-shaped stopper material 17 was inserted into 4. Here, the ribbon-shaped stopper material 17 has a width of 1 ion and a thickness of 35
A μm copper ribbon was used. Next, as shown in FIG. 2(b), the punch 13 was fixed to an actuator 19 that can move up and down, and the punch 13 was moved downward by the actuator I9. The punch holder 11 and the first die 15 moved downward together, and the first die 15 came into contact with the inner lead 18 .

When the actuator 19 is further moved downward, since a part of the punch holder 11 has an elastic body (spring) structure, the elastic body +2 (spring) contracts, and the lower holder portion 11b of the punch holder 11 comes into contact with the inner lead 18. In this state, the upper holder part 11a and the punch 13 moved downward, and the punch 13 and the first die 15 punched out a reinforcing stopper material 20 with a height of about 35 pm and a diameter of 35 μm. Furthermore, when the punch 13 that protrudes through the through hole formed in the stopper material 17 is moved downward by the actuator 19 continuously with the process shown in FIG. 2(b), the punched stopper material 20 is pressed down by the punch I3. The second die 1 moves downward and is pressed down by the punch 13.
The inner reed 18 on the top 6 was press-molded. When the actuator 19 was moved 4011 m downward after the stopper material 20 came into contact with the inner lead 18, the stopper material 20 was embedded in the inner lead 18, and the fourth
Height 35±2pm, diameter 50μm as shown in figure (a)
A bump 21 having a hollow structure was formed. At this time, the stopper material 20 was embedded to a depth of about 16 μm from the back surface of the bump, as shown in FIG. 4(a). Stopper material 2
0 undergoes plastic deformation when embedded in the inner lead 18, so the diameter widens and the height decreases. here,
The diameter of the stopper material 20 after being embedded is approximately 42p.
It was m.

As described above, the hollow structure bumps 21 as shown in FIG. 4(a) are formed on the plurality of inner leads 18 of the TAB tape.
is formed and bonded to the AQ electrode part of the semiconductor element using a low-temperature bonding method (element heating temperature: 150°C, pressure tool temperature: 50°C).
0℃, pressure crab 60gf/IJ-de, bonding time 1 second)
As a result of joining, a good connection was achieved both in terms of strength (shear strength of 60 gf or more per lead) and electrically. It was also confirmed that the height of the bump after thermocompression bonding was 20Flll, which was a sufficient height, and that it could be used as a bump for a TAB inner lead. In addition, despite the variation of ±2 μm in bump height, 60 g
The reason why a good connection could be achieved with the pressure of r/lead is that the bump 21 has a hollow structure and has a characteristic of being easily plastically deformed.

(Example 2) Next, regarding Example 2 of the present invention, FIGS. 3(a) to (d)
This will be explained in detail with reference to. As the bump forming apparatus, the TAB inner lead bump forming apparatus shown in FIG. 1 was used as in Example 1 of the present invention.

First, as shown in FIG. 3(a), a ribbon-shaped stopper material 17 is punched out using a first die 15 and a punch 13.
A through hole 22 with a diameter of 35 pm is formed in the ribbon-shaped stopper material 17.
was formed. The ribbon-shaped stopper material I7 used here was a copper ribbon having a width IM and a thickness of 25 pm. Next, as shown in FIG. 3(c), the inner lead 18 is placed between the first die 15 and the second die 16, the actuator 19 is moved downward, and the through hole 22 of the stopper material 17 is
The inner lead 18 is press-formed using the punch 13 that protrudes and the second die 16, and the bump 21 has a hollow structure with a diameter of 50 μm and a height of 30±2 μm as shown in FIG.
was formed. A guide hole 23 was formed on the back surface of the hollow bump 2J. Here, when the punch 13 is moved downward by the actuator 19, the punch 13 passes through the through hole 22 formed in FIG.
Only 8 is press-molded. Note that the formed guide hole 23
had a diameter of 30 μm and a depth of 40 μm.

Next, as shown in FIG. 3(c), the ribbon-shaped stopper material 17 was moved, and the position of the through hole 22 was moved.

Finally, the punch 13 was moved downward by the actuator 19 as shown in FIG. The ribbon-shaped stopper material 17 was punched out using a punch I3 and the first die 15 to form a reinforcing stopper material 20 having a diameter of 35 μm and a height of 25 μm. When the punch 13 is further continuously moved downward and the stopper material 20 is pressed down by the punch 13, the stopper material 20 moves downward together with the punch 13, and the guide hole formed in FIG. A stopper material 20 was embedded in 23. The diameter of the embedded stopper material 20 is approximately 35 pm, and the inner lead 18
There was almost no change in shape compared to before implantation. This is because the guide hole 23 having a diameter slightly smaller than the diameter of the stopper material 20 is formed in advance in the inner lead 18, and when the stopper material 20 is embedded, almost no plastic deformation occurs in the stopper material 20. This is because there was no such thing. On the other hand, the bump 21 having a hollow structure has a stopper material 20.
Plastic deformation occurs when embedding the bump, and the bump height is 35pm.
It increased to ±2pm.

As described above, the hollow structure bumps 21 as shown in FIG. 4(c) are formed on the plurality of inner leads 18 of the TAB tape.
and low temperature bonding method (element heating temperature: 150°C, pressure tool temperature: 50°C) with the AQ@extreme part of the semiconductor element.
As a result of bonding at 0° C., pressure +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 11 gies) and electrically. Furthermore, the bump height after thermocompression bonding was 20 pm, which was a sufficient height, and it was confirmed that it could be used as a bump for a TAB inner lead. In addition, the bump height is ±2pm.
The reason why a good connection could be achieved with a pressure of 60 g f/lead despite the variation in the amount of pressure is because the bump 2I has a hollow structure and has a characteristic that it easily undergoes plastic deformation.

[Advantageous Effects of the Invention 1] As explained above, the TAB inner lead bump forming apparatus of the present invention has the effect of easily forming a bump having a hollow structure in which a stopper material is embedded. Furthermore, according to the TAB inner lead bump forming method of the present invention, even if there is variation in the height of the bumps, all the bumps can be mechanically and electrically well connected to the electrode portions of the semiconductor element. Moreover, it is possible to easily form a hollow bump having a stopper material injected therein to ensure a sufficient bump height after bonding.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a TAB inner lead bump forming apparatus according to the present invention, and FIGS. 2(a) to (c) show a process order of a TAB inner lead bump forming method according to Embodiment 1 of the present invention. 3(a) to 3(d) are sectional views showing the method for forming bumps on a TAB inner lead according to Example 2 of the present invention in the order of steps, and FIGS. A sectional view showing a bump with a hollow structure formed in the example, FIG. 5(a) is a sectional view illustrating the problems of the conventional method,
(b) is the same plan view, and (c) is the same side view.

Claims (3)

[Claims] (1) A method for forming a bump on a TAB inner lead, which includes a stopper material punching step, a transfer step, and a stopper material embedding/bump forming step, wherein the stopper material punching step is performed using a pair of first dies. This is a process of punching out a reinforcing stopper material from the ribbon-shaped stopper material fed between the ribbon-shaped stopper material and the punch, and the transfer process involves rolling down the through-hole formed in the ribbon-shaped stopper material with a punch that protrudes. and extruding the reinforcing stopper material toward the second die, and the stopper material embedding/bump forming step pushes the inner lead supported by the second die through the reinforcing stopper material into the punch. In this step, a bump with a dome-shaped hollow structure is formed on the inner lead by pressing down with a punch, and a reinforcing stopper material that has been punched is press-fitted into the formed bump with a dome-shaped hollow structure and embedded. 1. A method for forming bumps on a TAB inner lead, characterized in that: (2) A TAB inner lead bump forming method comprising a through hole forming step, a bump forming step, a stopper material punching step, and a stopper material transfer/embedding step, wherein the through hole forming step includes a pair of This is a step of punching a through hole in a ribbon-shaped stopper material fed between a first die and a punch, and the bump forming step is a step of punching a through hole in a ribbon-shaped stopper material fed between a first die and a punch. The step of forming a bump having a dome-shaped hollow structure on the inner lead by further pressing down the through hole formed in the ribbon-shaped stopper material with a protruding punch, and the step of forming the stopper material includes pressing the punch and the first die. This is a step of punching the unpunched region of the ribbon-shaped stopper material fed between the ribbon-shaped stopper material and the reinforcing stopper material, and the stopper material transfer and embedding step The reinforcing stopper material is extruded toward the second die by the punch protruding through the stopper material, and is punched into the bump of the dome-shaped hollow structure of the inner lead supported by the second die. The reinforcing stopper material is press-fitted and embedded. First, when forming the bump of the TAB inner lead, there are a through hole forming process, a bump forming process, a stopper material punching process, and a stopper material transfer/embedding process. A method for forming bumps on a TAB inner lead, characterized in that the steps of forming a bump, punching a stopper material, and transferring and embedding a stopper material are repeated from the next time onwards. (3) A TAB inner lead bump forming apparatus having first and second dies and a single punch shared by both dies, wherein the first die supports a ribbon-shaped stopper material. The ribbon-shaped stopper material is punched by the punch, and is provided with a die hole penetrating vertically through the ribbon-shaped stopper material, and the second die supports the inner lead and is punched by the punch. The inner lead is provided with a die hole that forms a bump having a dome-like hollow structure, and the first die and the second die are arranged such that the axes of the die hole and the die hole are aligned with each other. The die is arranged in the upper stage and the second die is arranged in the lower stage, and the punch passes through the die hole of the first die and the second die.
1. A bump forming device for a TAB inner lead, characterized in that the device has a movement stroke that reaches a die hole of a die.