JPS6127089Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Technical Field> The present invention relates to a device for connecting two wiring boards provided with electrical wiring.

<Prior art> Conventionally, when two printed wiring boards are electrically connected by soldering, a gold plating film D is applied to the surface of the connection terminal portion of the copper foil electrical wiring C of each board A and B as shown in FIG. , there was a drawback that an intermetallic compound was formed between the solder layer E and the gold plating film D, resulting in a decrease in soldering strength. Furthermore, since it is bonded with solder, it requires high-temperature treatment (approximately 200 degrees Celsius), which requires the substrate to be heat resistant, making the substrate material expensive.
Furthermore, direct connections using solder sometimes caused lead pollution.

<Purpose> In view of the above points, the present invention has been developed to prevent precipitation of intermetallic compounds due to soldering, to prevent lead pollution, and to reduce the cost of board materials and to facilitate connection when replacing wiring boards. The present invention aims to provide a possible wiring board connection device.

<Embodiment> An embodiment of the present invention will be described below based on FIGS. 1 to 5. In this embodiment, a display element board 1 such as an LCD or ECD and a hard printed wiring board 2 are combined into a flexible wiring board. It is connected with 3,
At the connecting portion between the two substrates 2 and 3, solder plating films 6 and 7 are formed on the surfaces of the connection terminal portions 4a and 5a on one end side of the plurality of copper foil electrical wiring lines 4 and 5 of each of the substrates 2 and 3. A conductive adhesive layer 8 is formed on the surfaces of the plating films 6 and 7, and both conductive adhesive layers 8 are adhered to each other. The conductive adhesive layer 8 is made of a thermoplastic synthetic resin such as synthetic rubber or polyester, or a thermosetting synthetic resin such as epoxy or phenol, in which conductive powder such as carbon or silver is dispersed.

Also, between the connection terminal portions 4a, 4a of the wirings 4, 5 of the substrates 2, 3 (or one substrate), and between the connection terminal portions 4a, 5a,
Insulating adhesive layers 9 and 10 made of thermoplastic resin such as polyamide and polyester are applied between the substrates 2 and 5a by screen printing, etc., and the adhesive layers 9 and 10 on both substrates 2 and 3 are mechanically bonded by thermocompression bonding. are adhesively connected to each other.

On the other hand, at the connection part between the flexible wiring board 3 and the display element board 1, a gold plating film 11 is formed on the surface of the connection terminal part 4b on the other end side of the copper foil electrical wiring 4 of the board 3. Alternatively, the conductive adhesive layer 8 may be formed on the surface of the plating film 11, and an insulating adhesive layer 9 similar to that described above may be formed between the terminal portions 4b, 4b to form the flexible wiring board. 3 is electrically and mechanically adhesively connected to the display element plate 1 made of glass by thermocompression bonding.

Note that 14 in the figure is a lead portion for connecting elements such as LSI.

In the above configuration, when connecting the flexible wiring board 3 and the hard wiring board 2, the conductive adhesive layer 8 on the solder plating films 6, 7 of both the boards 2, 3 is connected with a heater block (not shown). Low temperature (approx.
Connect by thermocompression at 100℃). At the same time, the connecting terminal portions 4a, 4a and/or 5
The insulating adhesive layers 9 and 10 between a and 5a are also bonded together by thermocompression, and both substrates 2 and 3 are more firmly connected.

In addition, a flexible wiring board 3 and a display element board 1
When connecting the terminal parts 4b with the conductive adhesive layer 8 and the terminal parts with the insulating adhesive layer 9, soldering is difficult because the display element board 1 is made of glass. Nevertheless, the connection can be made more firmly, and the electrical conductivity of the connection portion can also be improved.

And, in connection of the above-mentioned both boards 2 and 3,
Since the solder plating films 6 and 7 of both substrates 2 and 3 are connected by the conductive adhesive layer 8, intermetallic compounds can be prevented from being deposited between the plating films 6 and 7 of the same type of metal. In addition, since the electrical wiring of both wiring boards 2 and 3 is connected by the conductive adhesive layer 8, relatively low temperature treatment (approximately 100°C) is possible, preventing the precipitation of intermetallic compounds, and improving the heat resistance of the board material. There is no need to take this into account, there are fewer restrictions on materials, the cost is lower, and lead pollution, which occurs when connecting directly with solder, can be relatively prevented.

It should be noted that the present invention is not limited to the above embodiments, and it goes without saying that many modifications and changes can be made to the above embodiments within the scope of the present invention.

For example, the conductive adhesive layer 8 does not need to be formed on both substrates as in the above embodiment, but may be formed on only one of the substrates.

<Effects> As is clear from the above description, the present invention provides a device for connecting two boards with electrical wiring, in which a solder plating film is formed on the surface of the connection terminal portion of the electrical wiring of both boards. The present invention relates to a wiring board connection device, characterized in that a conductive adhesive layer is formed on the surface of the solder plating film of at least one of the two boards.

Therefore, according to the present invention, since the electrical wiring of both wiring boards is connected by a conductive adhesive layer, it is possible to perform relatively low-temperature processing, prevent precipitation of intermetallic compounds, and take into consideration the heat resistance of the board material. It has the excellent effect of being able to reduce the cost because it requires less restrictions on materials, and also being able to relatively prevent lead damage that would otherwise occur when connecting directly with solder.

[Brief explanation of the drawing]

Figures 1 to 5 show an embodiment of the present invention. Figure 1 is a perspective view of a case where a display element board and a hard wiring board are connected by a flexible wiring board, and Figure 2 is a perspective view of a flexible wiring board. 3 is a plan view of the hard wiring board, FIG. 4 is an enlarged sectional view showing the connection terminal on the other end of the wiring of the flexible board, and FIG. 5 is an enlarged sectional view of the wiring board.
FIG. 6 is an enlarged sectional view of a conventional wiring board. 1: Display element board, 2: Hard wiring board, 3: Flexible wiring board, 4, 5: Copper foil electrical wiring,
6, 7: solder plating film, 8: conductive adhesive layer,
9, 10: Insulating adhesive layer, 11: Gold plating layer.

Claims (1)

[Scope of utility model registration request] In a device for connecting two boards with electrical wiring, a solder plating film is formed on the surface of the connection terminal portion of the electrical wiring on both boards, and the solder plating film on at least one of the two boards. A wiring board connection device characterized in that a conductive adhesive layer is formed on the surface of the wiring board.