JPH0223992B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a connection method for connecting an extraction electrode provided on a rigid flat display panel and a flexible printed circuit board using an anisotropic conductive film.

<Prior art> In recent years, rigid flat display panels with a matrix electrode configuration have been actively developed, and thin-film EL (electroluminescent) panels, plasma display panels, liquid crystal dot matrix panels, etc. have been commercialized. It is being done. These panels have a large number of fine extraction electrodes, and require one-to-one interconnection with driving elements. It is required that this interconnection be performed reliably and inexpensively.

Conventionally, solder has been mainly used for such terminal connections, but as panels become larger and pitches become finer, problems such as solder bridging and thermal deformation of connection materials due to high-temperature processing have arisen.

In order to solve these problems, anisotropic conductive films have been developed in recent years.This is a polymer film that has adhesive, conductive, and insulating properties, and can be permanently fixed without selecting a specific pattern pitch. It has the feature that conductivity between corresponding electrodes and insulation between patterns can be formed at the same time, and the processing temperature is lower than that of solder.
It also has the advantage of not having to select the terminal film. Therefore, it is judged to be the most suitable material to solve the above-mentioned problems with solder.

As a connection method using this anisotropic conductive film, the hot press method is generally known, in which the connecting part between the lead electrode part of the flat display panel and the flexible printed circuit board is pressurized using a block with a built-in heater and bonded by thermocompression. It is being

FIG. 8 is a front view showing the configuration of a conventional example.

As shown in FIG. 8, a flat display panel 33 is set on a pedestal 38, and a flexible printed circuit board 34 is mounted with an anisotropic conductive film 39 sandwiched therebetween.
After alignment, it is temporarily fixed. A block 41 including a heater can be moved vertically by an air cylinder or the like, and is heated to a set temperature by the heater, and a silicone rubber 40 is attached to the tip of the block 41 to uniformly transmit pressure to the connection part. ing.

With the above configuration, block 4 including the heater
1 and the silicone rubber 40 downward, and the connection portion is bonded by thermocompression, thereby completing the connection.

However, although this method has the advantage of being able to process the process all at once and in a relatively short processing time, it also increases the temperature of the joint during thermocompression bonding, and the heater is not turned on while the temperature of the joint remains high. Since the containing block is removed, problems such as stretching of the flexible printed circuit board and deformation of the connecting material due to residual stress etc. occur.Furthermore, this causes connection failures such as poor conductivity and poor insulation, resulting in high fine pitches. However, problems remain in terms of application to larger screens.

<Object of the invention> Therefore, the object of the invention is to enable connection using an anisotropic conductive film instead of solder.
It is an object of the present invention to provide an effective method for preventing connection failures due to elongation, deformation, etc. of a connection material during connection, and enabling connection with high fine pitches.

<Structure of the Invention> In order to achieve the above object, the structure and operation of the present invention are such that panels to be connected are stacked and fixed on a flexible printed circuit board, hydrostatic pressure is applied to the lower surface of the flexible printed circuit board, and the upper surface of the panel is A heat source, such as infrared rays, provided in the The next terminal adjacent to the terminal is connected, and in the same way, the connection is made sequentially to expand the connected portion in the scanning direction of the heat source, thereby completing the connection between all the terminals.

<Example> Below, along with the apparatus used to implement the present invention,
Examples of the present invention will be described.

FIG. 1 is a plan view of an apparatus for carrying out the present invention, FIG.
This figure is a perspective view showing the heat source scanning means shown in FIG. 1, and FIG. 3 is a sectional view of the infrared spot lamp shown in FIG. 1 or 2. FIG. 6 is a half plan view showing the structure of a jig used in the above device, and FIG. 7 is a half sectional side view.

In FIGS. 6 and 7, the film 2 is attached to several places on the flange portion 22 of a container 21 made of deep-drawn metal material using gaskets 23a, 23b, a presser metal fitting 24, bolts 25a, 25b, and nuts 26.
Tighten and secure the periphery of 7. Therefore, container 21
and the film 27 form an airtight chamber 28. In short, the film 27 has airtightness, high temperature,
It is a material that can be elastically deformed under high pressure, has heat resistance and mechanical strength, and is, for example, a polyimide film. At the bottom of the container 21, an inflow pipe 29 for gas such as air, nitrogen gas, water, oil, etc. is provided. One end of the several clips 30 is fixed to the flange 22 by a tightening bolt 25, and the other end is pressed against a hard substrate 33 by a substrate holding jig 32 via a height adjustment screw 31. The clip 30 presses the flexible substrate 34 and, at the same time, its arm portion presses the film holding jig 36 via the spacer 35. The film holding jig 36 is made of a strong material such as metal that will not be deformed by the maximum pressure applied to the airtight chamber 28 and has an appropriate thickness. Since the substrates 33 and 34 are pressed so that they are substantially flat, the contact area at the connection portion between the substrates 33 and 34 becomes large despite the presence of the stepped portion, and a sufficiently strong connection is achieved.

As shown in the figure, in order to connect the flexible substrate 34 to each of the four sides of the substrate 33, the film holding jig 36 is formed over the entire outer periphery of the substrate 33. A heat sink 37 is provided to block the heat source received by the substrate holding jig 32 and to improve cooling at that part.

In the above connection device, infrared rays are emitted from the direction of arrow A shown in the figure.

Next, in FIG. 1, FIG. 2, and FIG. 3, the scanning means for moving the small infrared spot lamp 1 along the connection terminal strip includes a drive unit 2, a feed screw 3,
It consists of a guide shaft 4, a carriage 5, and a relay device 6. The small infrared spot lamp 1 is supported by an arm 7 on a carriage 5. The carriage 5 moves along the guide shaft 4 and parallel to the connection terminal strip. As shown in FIG. 3, the small infrared spot lamp 1 consists of an infrared lamp 8 and a reflector 9. Infrared rays generated by the infrared lamp 8 are reflected by a reflecting mirror 9, and the reflected light beams are condensed at a focal point.

Next, an embodiment of the present invention, ie, a method of using the above-described apparatus, will be described. The infrared rays are focused on one point on the connection terminal band and adjusted so as not to heat the presser jig 36 or the clip 30, the drive speed of the feed screw 3 is set, and the end point of the scan is set by the limit switch 6. The infrared lamp 8 moves as the feed screw 3 is driven, and the leads on the flexible film 27 and the terminals on the substrate 33 are successively heated and connected.

In addition, as a modified embodiment of the present invention, it is also possible to use four heat sources and connect each side in parallel.

FIG. 4 is a diagram illustrating adhesive force when connecting according to the present invention. Board 10 and lead wire 11
In order to determine the connection state, the tensile strength when the lead wire 11 was peeled off from the substrate 10 in the vertical direction was measured. Figure 5 shows an example of measurement when connected at a pitch of 1.33 lines/mm.

Since the anisotropic conductive film 12 is bonded not only under the lead wire 11 but also between adjacent leads by infrared irradiation, a larger bonding area can be expected compared to solder which connects only the lead wires.

Another embodiment of the present invention will be described below with reference to FIG.

FIG. 9 is a cross-sectional view showing the method. An anisotropic conductive film 43 and a liquid crystal cell 46 (45 is a polarizing plate)
It is the same as the conventional one up to the addition of FPC (flexible printed circuit board) 42. Next, the liquid crystal cell terminal section 44 is placed on the holding rubber plate 52 with the terminal section facing downward. The rubber plate is molded from silicone rubber. Next, place the presser glass 51 on top of the liquid crystal cell, and then place the upper presser metal fitting 51 on top of it.
put The presser metal fitting 50 is fixed to the lower presser metal fitting 53 with a tightening bolt 49. Further, in the holding fitting 50, a portion corresponding to the liquid crystal cell terminal portion is hollowed out (54: hollowed out portion). Next, pressure F is applied to the lower presser fitting 53 so that a predetermined pressure is applied substantially to the terminal portion of the liquid crystal cell. After making preparations in this manner, the liquid crystal cell terminal portion is heated by the infrared irradiation lamp 47. The infrared irradiation lamp 47 is guided by the guide rail 48 over the terminal of the liquid crystal cell in its length direction (from the front to the back of the drawing).
As it moves gradually, it is sequentially irradiated with light and heated.

With this method, the part of the anisotropic conductive film 43 that is irradiated with light by the infrared lamp 47 is melted and crimped while pressure is applied, and since the infrared lamp moves, the melted and crimped part is melted and crimped. This allows the product to cool naturally while still being added, which greatly improves quality. Also, the temperature is 200℃ in 2 to 3 seconds.
Since the temperature reaches close to 50 to 60°C in 2 to 3 seconds, there is no deterioration in workability.

Note that the upper presser metal fitting 50 also functions as a mask material for light shielding (heat source).

Although the above embodiment has been described using the connection between a liquid crystal cell and an FPC, its implementation is not limited to liquid crystal cells. For example, it may be applied to an EL panel, etc. It may also be used to connect a PWB (printed wiring board) and an FPC.

Furthermore, instead of moving the infrared irradiation lamp, a configuration may be adopted in which the display body, anisotropic conductive film, and FPC are moved.

As the pressure application method, a method other than the hydrostatic pressure method may be used. Moreover, it is also possible to use a heat seal connector instead of (anisotropic conductive film + FPC).

<Effects of the Invention> According to the present invention, only the connection points are heated locally, and the heating points move sequentially, so the amount of residual heat in the flexible film is significantly reduced, and the amount of residual heat caused by thermal expansion is significantly reduced. Strain and adhesive misalignment between leads and terminals have been eliminated.

In addition, in general, in the sequential connection method using local heating, a pressure difference occurs between the connected part and the unconnected part due to the melting and solidification of the anisotropic conductive film, and the "warpage" due to uneven stress distribution occurs over the entire surface. However, according to the present invention, the entire surface of the connection part is pressurized with a constant hydrostatic pressure, so even if warping or waviness occurs, the pressure acts evenly, ensuring a reliable connection between the leads and terminals. You get a connection.

In addition, even if the panel has warps or undulations, the pressure acts uniformly as described above, and a reliable connection can be obtained.

[Brief explanation of drawings]

FIG. 1 is a plan view illustrating an embodiment of the present invention. FIG. 2 is a perspective view illustrating a hot ray source feeding means according to an embodiment of the present invention. FIG. 3 is a sectional view of a small infrared spot lamp. FIG. 4 is a diagram illustrating adhesive force in connection according to an embodiment of the present invention.
FIG. 5 is a diagram showing an example of measurement of adhesive force according to an embodiment of the present invention. FIG. 6 is a half sectional view showing the structure of the present invention. FIG. 7 is a half-sectional side view showing the configuration of the present invention. FIG. 8 is a front view showing a conventional connection method. FIG. 9 is a sectional view illustrating another embodiment of the present invention. Explanation of symbols, 1...Infrared small spot lamp, 2...Drive unit, 3...Feed screw, 4...Guide shaft, 5...Reciprocating table, 6...Relay device, 21...
...Container, 27...Film, 28...Airtight chamber, 3
0... Clip, 33... Hard substrate (panel),
34...Flexible substrate.

Claims (1)

[Scope of Claims] 1. A connection device in which an anisotropic conductive film is used to bond a connecting portion between an extraction electrode portion provided on a rigid flat display panel and a flexible printed circuit board, comprising: The above panel is superimposed and fixed on top, hydrostatic pressure is applied to the lower surface of the flexible printed circuit board, and a heat source such as infrared rays provided above the panel is focused on the joint part to make the joint part anisotropic. Connected by a conductive film,
A multi-lead connection method characterized in that all connections are completed by sequentially moving the heat sources.