JP2002134564A - Pressured head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure head that can load a semiconductor device with a simple configuration and efficient workability, and additionally can prevent a partial separation of a fillet. SOLUTION: On an absorption surface 21 of the pressure head 20, a film 33 is formed of a fluororesin that is a material that has a small intermolecular force and surface energy as well as excellent heat resistance, non-adherence and solvent resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure bonding head for connecting a semiconductor element to an electric circuit, and more particularly to a pressure bonding head for connecting a semiconductor element such as an LSI to an electric circuit of a flexible wiring board in a liquid crystal display device. A crimping head.

[0002]

2. Description of the Related Art First, an example of a general liquid crystal display element in the above-described liquid crystal display device will be described with reference to FIG.

FIG. 3 shows a color liquid crystal display device of a color filter system, in which a transparent substrate 1 made of a material such as glass, which is disposed in parallel with a space therebetween, is used.
A, 1B, and both transparent substrates 1A, 1B
The outer periphery therebetween is sealed by a sealing material 2. Of these, a transparent common electrode 3A is disposed on the lower surface of one of the transparent substrates 1A positioned above so as to be in close contact therewith, and below the transparent common electrode 3A, a non-display area is covered. The light-shielding film 4 is disposed at the center.

Below the light-shielding film 4, an alignment film 6A for controlling the alignment of liquid crystal molecules in accordance with the voltage applied between the electrodes is provided so as to be in close contact therewith. Further, a polarizing plate 7A is provided on the upper surface of the glass substrate 1A.

On the other hand, a transparent segment electrode 3B is disposed on the upper surface of the transparent substrate 1B located below,
A color filter film 5 is disposed above the transparent segment electrode 3B. As a method of forming the color filter film 5, various methods such as a printing method, an electrodeposition method, a dyeing method, and a pigment dispersion method are conventionally known. An alignment film 6B is provided above the color filter film 5 so as to be in close contact therewith. Further, a polarizing plate 7B is provided on the lower surface of the transparent substrate 1B.

A liquid crystal 8 is sealed in a sealed space surrounded by the transparent substrates 1A and 1B and the sealing member 2, and furthermore, the distance between the transparent substrates 1A and 1B is kept accurately and constant. For this purpose, the alignment films 6A, 6B
A plurality of spherical or columnar spacers 9 are interposed between them.

The transparent segment electrode 3B on the upper surface of the transparent substrate 1B is connected to the transparent substrate 1 via a conductive member (not shown) contained in the sealing material 2 or the like.
A lead terminal 3C of each of the electrodes 3A and 3B is formed at the right end in FIG. 3 of the lower surface of the transparent substrate 1A.

On the other hand, an electric circuit 13 is formed on a base film 12 of a flexible wiring board 11 shown in FIG.
The lead terminal 1 formed at the end of the electric circuit 13
The lead terminals 3C of the electrodes 3A and 3B are connected to 3A. Further, an LSI 14 as an example of a semiconductor element for controlling driving of the liquid crystal display element and a chip component 17 such as a capacitor are mounted on the electric circuit 13 of the flexible wiring board 11. And this flexible wiring board 1
1 is a curved portion 1 for reducing the plane area of the liquid crystal display device.
5 and is extended below the liquid crystal display element 10 as shown in FIG.
Is connected via a lead terminal 13B to a rigid printed wiring board 16 serving as a power supply side circuit located below.

Here, COF is used as the flexible wiring board 11.
(chip on film), TCP (tape carrier package) and the like.

In such a liquid crystal display device, the L
Conventionally, a crimping head has been used to connect the SI 14 to the electric circuit 13 of the flexible wiring board 11.

As shown in FIG. 6, the pressure bonding head 20, which has a substantially rectangular parallelepiped shape made of a ceramic material, can be raised and lowered by a lifting mechanism (not shown). Also,
The pressure bonding head 20 has a built-in heater (not shown) for heating the anisotropic conductive film to about 250 ° C. Further, a rectangular suction hole 22 is formed in the lower surface 21 of the pressure bonding head 20.
A vacuum pump (not shown) for sucking air is provided in the inside.

With such a crimping head 20, the LSI 1
In order to connect the bumps 4 (not shown) of FIG. 4 to the copper foil (not shown) of the electric circuit 13 of the flexible wiring board 11, as shown in FIG. Almost 50μ
m of an anisotropic conductive film (AC
F) 23 is formed, and air is sucked into the lower surface 21 of the crimping head 20 by suctioning air from the suction hole 22 of the lower surface 21 of the crimping head 20 in a high temperature state by a heater. Since the bumps of the LSI 14 and the copper foil of the electric circuit 13 are in direct contact with each other, an NCF (non-condu
ctive film) can also be used.

In such a state, the pressure bonding head 20 is moved down by the lifting / lowering mechanism to move the LSI 14 to the flexible wiring board 1.
It is mounted so as to be pressed against one electric circuit 13. Then
The anisotropic conductive film 23 rises at the outer peripheral portion of the LSI 14 to form a fillet 24 surrounding the LSI 14. The fillet 24 is indispensable from the viewpoints of mechanically holding the LSI 14 and preventing moisture from entering the LSI 14 and the electric circuit 13.

However, when the above-described fillet 24 comes into contact with the pressure bonding head 20 as shown in FIG. 8, when the pressure bonding head 20 is lifted, a part of the anisotropic conductive film 23 constituting the fillet 24 is removed. As shown in FIG. 9, there is a case where it is separated from the fillet 24 while being attached to the pressure bonding head 20.

Then, as shown in FIG.
An opening 25 will be formed in the fillet 24 at a position adjacent to the side surface of the opening. Then, the bumps of the LSI 14 and the copper foil of the electric circuit 13 are exposed through the openings 25, and the bumps and the copper foils may be corroded by moisture entering from the openings 25. There was a possibility that the intended purpose of the formation was deteriorated.

On the other hand, since the anisotropic conductive film 23 attached to the pressure bonding head 20 has reacted and solidified,
It took time and effort to remove the anisotropic conductive film.

For this reason, conventionally, as shown in FIG.
The LSI 14 is divided and mounted in two stages.

That is, in the first stage, the pressure bonding head 20
Is heated to a low temperature of 60 to 80 ° C., the LSI 14 is adsorbed to the pressure bonding head 20, and the pressure bonding head 20 is formed on the flexible wiring substrate 11 by the anisotropic conductive film 23.
The anisotropic conductive film 23 is softened by
4 is temporarily mounted. Thereafter, the pressure bonding head 20 is raised.

Next, in the second stage, the pressure bonding head 2
PTF for preventing the anisotropic conductive film 23 from adhering to the pressure bonding head 20 between the pressure bonding head 20 and the LSI 14 in a state in which the pressure-sensitive adhesive 0 is heated to a high temperature of 200 to 250 ° C.
An E (polytetrafluoroethylene) sheet 26 is interposed between the PTFE sheet 26 and the pressure bonding head 20.
Is lowered and mounted on the electric circuit of the flexible wiring board 11.

If the LSI 14 is mounted as described above,
The anisotropic conductive film 23 constituting the fillet 24 does not adhere to the pressure bonding head 20. Therefore, LSI14
The opening 25 is not formed in the fillet 24 on the adjacent portion of the side surface of the crimping head 2 and the intended purpose of forming the fillet 24 is not impaired.
From 0, there is no need to remove the anisotropic conductive film.

[0021]

However, if the LSI 14 is mounted using the PTFE sheet 26 as described above, the PTFE sheet 26 that has been used once must be used.
Has changed shape and cannot be reused.
The used PTFE sheet 26 has to be wound up onto the sheet roll 27B while sequentially feeding the TFE sheet 26 from the sheet roll 27A.

When mounting the LSI 14 using the PTFE sheet 26 as described above, the sheet roll 27
A, 27B and a means for running the PTFE sheet are required, which complicates the configuration and leads to an increase in cost. In addition, it has to be divided and mounted, resulting in poor workability.

The present invention overcomes the above-mentioned problems in the prior art, and enables a semiconductor device to be mounted with a simple structure with good workability, and furthermore, a crimping method which does not cause partial peeling of the fillet. It is intended to provide a head.

[0024]

According to the first aspect of the present invention, there is provided a pressure bonding head according to the present invention, wherein a fluorine-based resin film is formed on a suction surface. And
By adopting such a configuration, the adsorption surface of the pressure bonding head is covered with a fluorine resin film having a small intermolecular force and a low interfacial energy, so that the resin constituting the fillet adheres to the pressure bonding head and peels off. There is no danger.

A feature of the pressure bonding head according to the present invention according to claim 2 is that the film thickness of the coating is 20 to 50 μm. By adopting such a configuration, there is no fear that thermal conductivity from the pressure bonding head to the resin is impaired, and good durability can be obtained.

[0026]

FIG. 1 shows an embodiment of a crimping head 30 according to the present invention. The crimping head 30 of this embodiment has a substantially rectangular parallelepiped shape similarly to the above-described conventional one. The pressure bonding head 30 can be moved up and down by a lifting mechanism (not shown). Further, the pressure bonding head 20 has a built-in heater (not shown) for heating the anisotropic conductive film to about 250 ° C. Furthermore, on the lower surface 31 which is the suction surface of the pressure bonding head 30,
A rectangular suction hole 32 is formed.
2, a vacuum pump (not shown) for sucking air is provided.

Further, the lower surface 31 of the pressure bonding head 30 is detachably covered with a coating 33 made of a fluororesin such as PTFE, and a position of the coating 33 corresponding to the suction hole 32. Is formed with a suction hole 34.

The fluorine resin constituting the coating 33 is as follows:
Since the material has low intermolecular force and low interfacial energy, the thermal decomposition temperature varies depending on the type, but is 260 to 340.
It is excellent in heat resistance as high as ° C., and is also excellent in non-adhesiveness and solvent resistance.

Next, if the thickness of the film 33 is too small, the workability and the durability deteriorate, so the lower limit is 20 μm.
The upper limit is set to 50 μm because thermal conductivity deteriorates if the thickness is too large.

Next, the operation of the embodiment of the present invention having the above-described configuration will be described.

The above-described crimping head 30 allows the LSI 14
Of the electric circuit 1 of the flexible wiring board 11
2 is connected to a copper foil (not shown) as shown in FIG.
The anisotropic conductive film (ACF) 23 is formed so as to have a film thickness of 30 mm, and the pressure bonding head 30 which is in a high temperature state by a heater.
The LSI 14 is sucked into the lower surface of the coating 33 of the pressure bonding head 20 by sucking air from the suction holes 34 of the coating 33 made of a fluororesin. Note that NCF is used instead of the anisotropic conductive film 23.
Can also be used.

In such a state, the pressure bonding head 30 is lowered by the lifting mechanism to move the LSI 14 to the flexible wiring board 1.
It is mounted so as to be pressed against one electric circuit 13. Then
The anisotropic conductive film 23 rises at the outer peripheral portion of the LSI 14 to form a fillet 24 surrounding the LSI 14.

By the way, even if the above-described fillet 24 comes into contact with the pressure bonding head 30 as shown in FIG.
The fillet 24 adheres to the fluorine-based resin film 33 having excellent heat resistance and non-adhesiveness, so that when the pressure bonding head 30 is raised, one of the anisotropic conductive films 23 forming the fillet 24 is bonded. There is no possibility that the portion may be peeled off from the fillet 24 while being attached to the pressure bonding head 30.

As described above, the pressure bonding head 3 of the present embodiment
According to No. 0, the semiconductor element such as the LSI 14 can be mounted on the electric circuit 13 with good workability by single-stage mounting without performing temporary mounting, and the quality can be improved without causing the partial peeling of the fillet 24 as described above. Can be performed stably. In addition, according to the pressure bonding head 30 of the present embodiment,
Even when the semiconductor element is mounted on the electric circuit 13 by the temporary mounting and the split mounting including the main mounting, it is not necessary to use the PTFE sheet, so that the work can be performed with good workability.

[0035]

EXAMPLE The above-mentioned PTFE enamel was applied to the surface of the ceramic pressure bonding head which was in contact with the semiconductor element, and baked to form a fluororesin film having a thickness of 30 μm.

Using such a pressure bonding head, the thickness of the anisotropic conductive film, which is usually 30 μm, is set to 80 μm to ensure that the fillet reaches the pressure bonding head.
As a result, an experiment was conducted in which an LSI was mounted on an electric circuit. As a result, the anisotropic conductive film reached the pressure bonding head in a pressing time of 5 to 10 seconds. It was confirmed that the film did not adhere and that the fillet could not be opened. In this experiment, the number of samples was 20, the thickness of the flexible wiring board was 25 μm, the thickness of the copper foil of the electric circuit was 12 μm, the height of the LSI was 0.3 mm,
The SI bump having a height of 17 μm was used.

Under the same conditions as in this embodiment, an LSI mounting experiment was conducted using a conventional crimping head in which the surface of the crimping head which is in contact with the semiconductor element was not covered with a fluorine resin film. A part of the anisotropic conductive film constituting (1) was peeled off from the fillet, and an opening was formed in the fillet. As a result, the copper foil on the electric circuit to be protected is exposed.

Note that the present invention is not limited to the above-described embodiment, and various modifications can be made as necessary. For example, a flexible wiring board is illustrated as an example in which an electric circuit is formed, but a rigid wiring board may be used.

[0039]

As described above, according to the present invention, a semiconductor element can be mounted with a simple structure with good workability, and further, it is possible to prevent partial peeling of the fillet.

That is, since the fluorine resin coating is formed on the adsorption surface, the adhesion surface of the pressure bonding head is covered with the fluorine resin coating having a small intermolecular force and a small interfacial energy, and the resin constituting the fillet is formed by the compression head. There is no danger of sticking to and peeling off. Therefore, the workability can be improved, the quality can be stabilized, and the yield can be improved.
As a result, costs can be reduced.

Further, the thickness of the fluorine-based resin film is set to 20 to
When the thickness is 50 μm, the thermal conductivity from the pressure bonding head to the resin is not impaired, and good durability can be obtained.

[Brief description of the drawings]

FIG. 1 is a view showing an embodiment of a pressure bonding head according to the present invention, wherein (A) is a perspective view and (B) is a bottom view.

FIG. 2 is a perspective view showing a state where a semiconductor element is mounted on an electric circuit by the pressure bonding head of FIG. 1;

FIG. 3 is a longitudinal sectional view showing an example of a general liquid crystal display element.

FIG. 4 is a front view schematically showing a general liquid crystal display device.

FIG. 5 is a plan view showing the flexible wiring board of FIG. 4;

6A and 6B are views showing a conventional pressure bonding head, wherein FIG. 6A is a perspective view and FIG.

FIG. 7 is a perspective view showing a state where a semiconductor element is mounted on an electric circuit by the pressure bonding head of FIG. 6;

FIG. 8 is a perspective view showing a state where a semiconductor element is mounted, proceeding from the state shown in FIGS. 2 and 7;

FIG. 9 is a perspective view showing a state in which the position of the fillet is attached to the pressure bonding head, proceeding from the state of FIGS. 7 and 8;

FIG. 10 is a plan view showing an opening of a fillet in the state of FIG. 9;

FIG. 11 is a front view showing a divided mounting state of a conventional semiconductor element in two stages.

[Explanation of symbols]

 1A, 1B Transparent substrate 2 Sealing material 3A Transparent common electrode 3B Transparent segment electrode 3C Lead terminal 8 Liquid crystal 9 Spacer 10 Liquid crystal display element 11 Flexible wiring board 12 Base film 13 Electric circuit 15 Curved portion 15C Flat portion 16 Printed circuit board 17 Chip Component 20 Crimping head 21 Lower surface 22 Suction hole 23 Anisotropic conductive film 24 Fillet 25 Opening 26 PTFE sheet 30 Crimping head 31 Lower surface (suction surface) 32 Suction hole 33 Fluororesin coating 34 Suction hole

Claims (2)

[Claims] 1. A pressure bonding head having an adsorption surface for adsorbing a semiconductor element and connecting said semiconductor element and an electric circuit via a resin adhesive by pressure and heat, wherein said adsorption surface is made of a fluororesin coating. Is formed. 2. The pressure bonding head according to claim 1, wherein the thickness of the coating is 20 to 50 μm.