JPH07118496B2 - TAB inner lead bump forming device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a TAB (Tape / Automated / Bo) used for mounting a semiconductor element.
The present invention relates to an apparatus for forming a bump on the tip of an inner lead of a tape carrier for a tape by a mechanical pressing method.

[0002]

2. Description of the Related Art Generally, in order to mount a semiconductor element on a TAB tape carrier, it is necessary to form a bump projection on either the electrode portion of the semiconductor element or the tip of the inner lead of the tape carrier. A method for forming bumps on the electrode portion of a semiconductor element is described in, for example, "IBM Journal", Vol. 8 (1).
(964) p. 102, a method of forming bumps that directly form bumps on the electrode portion by a plating method, or "Electronic Packaging & Production P."
,), December 1984, 33-.
As described on page 39, a pedestal method using an etching technique, that is, a portion where a bump is to be formed is masked and other inner lead portions are half-etched to form a protrusion having a height of 30 to 40 μm. Method, or "The 60th Annual Conference of the Institute of Electronics and Communication Engineers of Japan, Semiconductor and Materials Division, Lecture No. 2" (November 1985)
After forming bumps on the glass substrate as described in
A transfer bump method, which is a method of transferring bumps to electrode portions, is used.

However, in order to form bumps by these methods, not only expensive equipment such as an exposure apparatus and a plating apparatus are required, but also a lithography step and an etching step for patterning are required, so that bumps are required. There is a problem that the forming process also becomes long.

Therefore, in FIG. 7, (a), (b), (c)
(See Japanese Examined Patent Publication No. 64-10094),
A method of manufacturing the pedestal 25 at the tip of the inner lead using a mechanical press molding technique using a mold has been proposed. In this method, a tape carrier in which a film 27 and an inner lead 20 are integrated is attached to a lower die 26, and an upper die 29 having a protrusion 28 larger than the width of the inner lead is lowered from above to lower the inner lead 20.
In this method, the groove 30 is formed by pressing at the tip of the inner edge of the inner lead, and the pedestal 25 to be a bump is formed at the tip of the inner lead. A notch 31 is provided in the width direction in order to allow the material of the groove 30 of the inner lead 20 pressed by the convex portion 28 of the upper die 29 to escape.

[0005]

Generally, the inner lead for TAB is made of Cu foil with Au plating or Sn plating having a thickness of about 1 μm. The mechanical properties of the lead are almost the same as those of most lead materials. Is determined by the properties of the Cu foil. Since the bump formed by the conventional bump forming method as shown in FIG. 7 uses the inner lead material as the bump material, it becomes a Cu bump and is less likely to be deformed than the Au bump used in the transfer bump method or the like. It becomes a bump with a rigid structure.

Therefore, in the conventional bump as shown in FIG. 7, the bump is less likely to be deformed in thermocompression bonding between the Al electrode of the semiconductor element and the Au-plated bump.
The natural oxide film existing on the l-electrode could not be sufficiently destroyed, and the Al electrode and the Au-plated bump could not be joined with sufficient strength. In order to sufficiently destroy the natural oxide film on the Al electrode and increase the bonding strength, it is necessary to increase the load at the time of thermocompression bonding. Si under the electrode
There is a problem that the probability of cracks occurring in the SiO ₂ film and the SiO ₂ film increases, and the reliability of bonding decreases.

Therefore, as a bump structure for solving these problems, a bump 21 having a hollow structure as shown in FIG.
Alternatively, a bump having a structure in which the soft metal 22 or the like is embedded in a part of the hollow portion of the hollow bump as shown in FIG.
The bumps are formed by a mechanical pressing method using a punch 12 and a die 13 as shown in FIG.
This is performed by press molding the tip of No. 0. Since the bump 21 shown in FIG. 2 of the hollow structure, deformation is likely to occur compared with the conventional bump shown in FIG. 7, below the Al electrode Si and SiO ₂
Good bonding can be performed without cracks in the film.

Here, in order to form the bump 21 as shown in FIG. 5, a press working device for driving the punch 12 is required. Generally, since the press working apparatus uses hydraulic pressure as a drive source, there is a problem that the apparatus is large and high-speed operation is difficult. In addition, since the mechanism of the hydraulic press head is large, there is a problem that the cost of the apparatus increases.
Further, the bump formation needs to be performed in a clean room, but the conventional hydraulic press device has a problem of dust generation and is difficult to use in the clean room.

SUMMARY OF THE INVENTION An object of the present invention is to provide a bump forming apparatus for a TAB inner lead, which solves the conventional problems described above, can be used in a clean room, can operate at high speed, and is inexpensive.

[0010]

In order to achieve the above object, a bump forming apparatus for a TAB inner lead according to the present invention has a press head and a die,
A bump forming apparatus for a TAB inner lead, which mechanically forms bumps near a tip of the inner lead of a tape carrier for press, wherein a press head has a laminated piezoelectric element, an arm and a punch, and a laminated piezoelectric element. The element is
The punch is fixed to the head base of the press head as a driving source, the arm is attached to one end of the laminated piezoelectric element via an elastic hinge capable of circular motion, and the elastic hinge is a laminated The micro-displacement of the die-type piezoelectric element is enlarged and transmitted to the arm. The tip position is located on a line segment that passes through the center of rotation of the elastic hinge and is parallel to the expansion and contraction direction of the laminated piezoelectric element.
The dice are arranged on the stage so as to face the tip of the punch.

[0011]

In the TAB inner lead bump forming apparatus of the present invention, the laminated piezoelectric element 16 having excellent frequency response characteristics is used as the drive source of the press head 11 as shown in FIG. Since the size can be reduced, the press head 11 can be driven at a high frequency. Further, since the punch 12 is driven by the non-sliding guide mechanism using the elastic hinge 17, there is no problem of dust generation, and bumps can be formed in a clean room. Further, since the mechanism of the press head 11 is extremely simple and does not require expensive parts, the cost of the device can be reduced as compared with the conventional hydraulic press system.

Since the punch 12 is driven by an elastic hinge 17 to which the lever principle is applied, the minute displacement of the laminated piezoelectric element 16 is enlarged to a displacement sufficient to form bumps, and therefore, the tip of the punch 12 is driven. The movement is an arc movement. As shown in FIG. 6, the tip position of the punch 12 is an elastic hinge 1.
If it is not on the line segment passing through the rotation center 19 of 7, the movement direction 23 of the punch 12 and the center axis direction 24 of the die hole are largely deviated from each other, and bump formation cannot be performed. On the other hand, as shown in FIG.
When the punch 12 is disposed on a line segment that passes through the rotation center 19 of 7 and is parallel to the expansion / contraction direction of the laminated piezoelectric element 16.
It is possible to approximately match the movement direction 23 of the and the axial direction 24 of the die hole, and it is possible to form stable bumps.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. 1A and 1B respectively show
1A and 1B are a side view and a top view of a TAB inner lead bump forming apparatus used in an embodiment of the present invention. Figure 2 (a) shows
A cross-sectional view of a bump formed according to an embodiment of the present invention,
3 and 4 are side views of punches and dies used in an embodiment of the present invention.

As shown in FIG. 1, the TAB inner lead bump forming apparatus according to the present invention comprises a press head 11,
It is composed of a punch 12, a die 13, an XY stage 14, and the like. The press head 11 includes a head base 15, a laminated piezoelectric element 16 adhered and fixed to the head base 15, and an arm 18 connected to one end of the laminated piezoelectric element 16 via an elastic hinge 17. The punch 12 is fixed to the arm 18 so that its tip position passes through the rotation center 19 of the elastic hinge 17 and is located on a line segment parallel to the expansion / contraction direction of the laminated piezoelectric element 16. In the embodiment, the press head 11 and the die 13 are fixed on the XY stage 14, and the TAB tape is fixed.
The inner lead 2 is moved by moving the Y stage 14.
Bumps were sequentially formed on the surface of the substrate.

A punch 1 having a tip diameter of 30 μm shown in FIG.
2, and bumps were formed on the TAB tape having an inner lead width of 60 μm with the driving frequency of the press head 11 being 100 Hz, using the die 13 having a hole diameter φ45 μm shown in FIG. Here, the formation time per bump including the time for moving the press head 11 to the adjacent inner lead 20 by the XY stage 14 was set to 0.1 seconds. As a result, the diameter φ45μ as shown in FIG.
It was possible to form a uniform bump 21 with a height of 28 m, a height of 28 μm, and a height accuracy of ± 0.5 μm with high accuracy. The bump formation was performed in a class 100 clean room.

The bump 21 formed on the inner lead portion of the TAB tape is bonded to the Al electrode portion of the semiconductor element by a low temperature bonding method (element heating temperature: 150 ° C., pressure tool temperature: 450 ° C., pressure: 60 gf / lead, 2 seconds). As a result of the ganging method according to (1), it was confirmed that a good connection with the Al electrode of the semiconductor element can be achieved, and it can be sufficiently used as a bump for the inner lead. It was also confirmed that no cracks were generated on the Si and SiO ₂ surfaces after bonding.

[0017]

As described above, according to the bump forming apparatus for TAB inner leads of the present invention, since the structure of the press head is simple, the apparatus can be manufactured inexpensively, and the laminated piezoelectric element is used as the driving source. Since it has a press head capable of high-speed operation, it is possible to form bumps with high productivity, and since the press head has no sliding portion, there is no problem of dust generation and there is an effect that it can be used in a clean room.

[Brief description of drawings]

FIG. 1 is a diagram showing a bump forming apparatus for a TAB inner lead, in which (a) is a side view and (b) is a top view.

2A and 2B are cross-sectional views of a hollow structure bump.

FIG. 3 is a side view of a punch used in an embodiment of the present invention.

FIG. 4 is a side view including a partial cross-sectional view of a die used in an example of the present invention.

FIG. 5 is a side view showing a method for forming a hollow structure bump.

FIG. 6 is an explanatory diagram showing a relationship between a punch tip position and a punch movement locus.

FIG. 7 is a diagram showing a conventional bump forming method, (a)
(C) is a figure which shows a process in process order.

[Explanation of symbols]

 11 Press Head 12 Punch 13 Die 14 XY Stage 15 Head Base 16 Laminated Piezoelectric Element 17 Elastic Hinge 18 Arm 19 Center of Rotation 20 Inner Lead 21 Bump 22 Soft Metal 23 Punch Movement Direction 24 Die Hole Center Axis 25 Pedestal 26 Lower Model 27 Film 28 Convex part 29 Upper mold 30 Groove 31 Notch

Claims (1)

[Claims] 1. A TAB having a press head and a die.
A bump forming apparatus for a TAB inner lead, which mechanically forms bumps near a tip of the inner lead of a tape carrier for press, wherein a press head has a laminated piezoelectric element, an arm and a punch, and a laminated piezoelectric element. The element is
The punch is fixed to the head base of the press head as a driving source, the arm is attached to one end of the laminated piezoelectric element via an elastic hinge capable of circular motion, and the elastic hinge is a laminated The micro-displacement of the die-type piezoelectric element is enlarged and transmitted to the arm. The tip position is located on a line segment that passes through the center of rotation of the elastic hinge and is parallel to the expansion and contraction direction of the laminated piezoelectric element.
The TAB inner lead bump forming apparatus is characterized in that the die is arranged on the stage so as to face the tip of the punch.