JP2000307207A - Connecting part of printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a connecting part of a printed wiring board where electrical connecting performance of contact with a terminal is improved. SOLUTION: In this connecting part 4, a conducting layer 2 where a printed layer 2b of conductive paste whose main component is carbon is stacked on a printed layer 2a of conductive paste whose main component is silver is connected with a terminal of a printed wiring board formed on an insulating film 1. In this case, the printed layer 2a of the conductive paste whose main component is silver is exposed in an electrical connecting part with the terminal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connection portion for connecting a terminal of a printed wiring board having a conductive layer formed by printing a conductive paste on a plastic film.

[0002]

2. Description of the Related Art As shown in FIG. 2, for example, a printed wiring board is formed by forming a conductive layer 2 by printing a conductive paste on the surface of a flexible insulating plastic film 1 (eg, polyethylene terephthalate: PET). The coating layer 3 is laminated on the plastic film 1 so as to sandwich the conductive layer 2. The conductive layer 2 has a two-layer structure, and a carbon paste layer 2b made of a conductive paste mainly containing carbon is superimposed on a silver paste layer 2a made of a conductive paste mainly containing silver serving as a base. It is formed by printing. The reason why the conductive layer 2 has the two-layer structure is as follows. That is, the silver paste layer 2a
Both have low volume resistance and low surface resistance, and have good properties as a conductive layer, but have the disadvantage that migration is likely to occur when a voltage is applied in high humidity or in an environment where water droplets adhere. Therefore, the silver paste layer 2a is covered with the carbon paste layer 2b in which migration hardly occurs, thereby preventing silver migration. The covering layer 3 is made of a flexible insulating plastic film (for example, PET) or an electrically insulating adhesive layer printed at an appropriate thickness. Note that the coating layer 3 does not cover the entire surface of the plastic film 1 but partially exposes the conductive layer 2 as needed (for example, a portion connected to a terminal).

The connection of the terminal to the connection portion of the printed wiring board is performed, for example, as follows. That is, FIG.
As shown in (1), the connecting portion 4 is formed by exposing the carbon paste layer 2b and shaping the outer shape into a tongue shape so that the carbon paste layer 2b can be inserted into the terminal. As shown in FIG. 3B, the connecting portion 4 is inserted into the terminal 10, and the substantially semispherical projection 13 of the elastic tongue 11 of the terminal 10 and the circular hole 1 formed in the terminal bottom 12.
4 and is electrically connected between the protrusions 1.
3 and the carbon paste layer 2b. Reference numeral 15 denotes a stopper that locks a protruding portion (not shown) that protrudes on both sides of the tip of the elastic tongue 11 to maintain a state in which the elastic tongue 11 presses the connecting portion 4.

[0004]

As described above, the terminal 1
The electrical connection between 0 and the connection portion 4 of the printed wiring board is made by contact between the projection 13 of the elastic tongue 11 of the terminal 10 and the carbon paste layer 2b of the printed wiring board. However, the carbon paste layer 2b has a higher electric resistance than the silver paste layer 2a, and particularly has a significantly higher surface resistance. For this reason, the electrical connection performance such as the contact resistance and the change with time of the contact resistance is different from the silver paste layer 2a.
There is a problem that it is reduced as compared with the case where the contact is made.

An object of the present invention is to provide a connection portion of a printed wiring board with improved electrical connection performance at the connection portion of the printed wiring board.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above problems, and has a printing layer of a conductive paste mainly composed of silver on an insulating film and a conductive layer mainly composed of carbon on the printed layer. In the connection portion between the printed wiring board on which the conductive layer on which the paste printed layer is formed and the terminal is connected, the electrical connection portion with the terminal of the printed wiring board is a printed layer of conductive paste mainly composed of silver. Are exposed.

As described above, according to the present invention, the terminal is electrically connected to the terminal because the printed layer of the conductive paste mainly composed of silver is exposed. The printed layer of the paste makes electrical contact. Therefore, the electrical connection performance such as the contact resistance and the change over time of the contact resistance is improved as compared with the conventional case where the printed layer of the conductive paste mainly composed of carbon contacts the terminal. At this time, when the region where the printed layer of the conductive paste mainly composed of silver is exposed is localized in the region that contacts the terminal, the exposed region is exposed to the outside air in the state of contact with the terminal. And migration can be prevented.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1A and 1B are a perspective view of an embodiment of a connection portion of a printed wiring board according to the present invention and a partial cross-sectional view of a state where the embodiment is connected to a terminal. In FIG. 1, the same parts as those described with reference to FIG. 3 are indicated by the same reference numerals. As shown in FIG. 1A, in the printed wiring board of the present embodiment, a conductive paste is printed on the surface of a flexible insulating plastic film 1 (for example, polyethylene terephthalate: PET) to form a conductive layer 2. A coating layer 3 is laminated on a plastic film 1 so as to sandwich the conductive layer 2. The conductive layer 2 is formed by printing a conductive paste mainly composed of carbon on a silver paste layer 2a on which a conductive paste mainly composed of silver is printed, so as to overlap the carbon paste layer 2a.
b is formed. In addition, the connecting portion 4 for connecting the terminal is not covered with the coating layer 3, the carbon paste layer 2 b is exposed, and the outer shape has a tongue shape so that it can be inserted into the terminal. This embodiment is different from the conventional example in that
The silver paste layer 2a is exposed in a circular shape at a portion 4a of the connection portion 4 which contacts the terminal. Printing the carbon paste layer 2b on the silver paste layer 2a so that the silver paste layer 2a is partially exposed as described above can be easily performed by a screen printing technique.

FIG. 1B is a sectional view showing a state in which the elastic tongue 11 of the terminal is pressed against the connecting portion 4. The connection unit 4
A substantially hemispherical protrusion 13 of the elastic tongue 11 and a terminal bottom 12
Elastically sandwiched between the holes 14 formed in the silver paste layer 2a.
The contact is made. Therefore, in the electrical connection at the connection portion of the present embodiment, the electrical connection performance is improved, for example, the contact resistance is reduced, as compared with the conventional case where the protrusion 13 and the carbon paste layer 2b are in contact with each other. . The exposed silver paste layer 2a of the connection portion 4 is formed by the elastic tongue 11
Is not exposed to the outside air in contact with the protrusions 13 of the above, there is no risk of migration occurring.

In the above-described embodiment, the shape of the exposed portion of the silver paste layer 2a in the connection portion 4 is circular. However, the shape is not limited to a circle, and the elastic tongue piece 11 of the terminal may be used.
Can be changed depending on the shape of the contact portion.

[0011]

As described above, according to the present invention, there is an excellent effect that the electrical connection performance by contact with the terminal is greatly improved.

[Brief description of the drawings]

FIGS. 1 (a) and 1 (b) are a perspective view of an embodiment of a connection portion of a printed wiring board according to the present invention and a partial cross-sectional view of a state where the embodiment is connected to a terminal.

FIG. 2 is a sectional view of a printed wiring board.

FIGS. 3 (a) and 3 (b) are a perspective view of a connection portion of a conventional printed wiring board and a partial cross-sectional view of a state where the connection portion is connected to a terminal.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plastic film 2 Conductive layer 2a Silver paste layer 2b Carbon paste layer 3 Coating layer 4 Connection part 4a Contact part 10 Terminal 11 Elastic tongue piece 12 Terminal bottom part 13 Projection part 14 Round hole

Claims (1)

[Claims] 1. A printed wiring board and a terminal having a conductive layer formed by superposing a printed layer of a conductive paste mainly composed of silver on an insulating film and a printed layer of a conductive paste mainly composed of carbon on the insulating film. A printed circuit board made of a conductive paste mainly composed of silver is exposed at an electric connection part with a terminal of the printed wiring board.