Electricity: conductors and insulators – Conduits – cables or conductors – Preformed panel circuit arrangement
Reexamination Certificate
1997-06-13
2001-07-24
Paladini, Albert W. (Department: 2841)
Electricity: conductors and insulators
Conduits, cables or conductors
Preformed panel circuit arrangement
C361S803000, C439S066000, C439S074000, C439S078000
Reexamination Certificate
active
06265674
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a terminal connecting structure of a flexible board and a printed circuit board, and more particularly relates to a terminal connecting structure of the type for pressing a connecting portion of a flexible board into contact with a land portion of a printed circuit board to make connection thereof.
2. Description of the Related Art
In a connecting structure employed for example in a keyboard input device, a membrane sheet (flexible board) is used as a switching device to be operated by a depression of each keytop, thereby electrically connecting an output part of the membrane sheet and a printed circuit board that mounts circuit component parts.
In the known connecting structure of this type, an exclusive connector having a plurality of clip-like contacting elements is soldered onto the printed circuit board so that terminals of the two boards are conductive through the contacting elements by inserting an end portion of the membrane sheet into the connector. Since, however, such connector requires the plurality of clip-like contacting elements and an insulating case for containing these elements, a complicated structure is unavoidable and a higher cost results.
On the other hand, the terminal connecting structure of flexible board and printed circuit board proposed by the present applicant in Japanese Utility Model Laid-Open Publication No.62-76477 includes a holding member fixed to the printed circuit board and flexible board through an elastic sheet. The respective terminals of the printed circuit board and flexible board are pressed into contact with each other by the elastic sheet so as to conduct electricity. In this construction, since the terminal on the printed circuit board and the terminal on the flexible board are pressed into contact with each other by the resilient force from the elastic sheet, a high-priced exclusive connector can be omitted to achieve a reduction in cost.
If, however, the corresponding terminals on the flexible board are brought into direct contact with the respective terminals on the printed circuit board in the terminal connecting structure of the conventional pressure-connected type as described, a sufficient contacting pressure cannot be secured because the respective terminals come into contact at their flat surface. Although a method may thus be considered of increasing the contacting pressure by previously applying solder to land portion of each terminal of the printed circuit board and bringing the terminal on the flexible board into contact with a curved surface of the solder, the height dimension of each solder tends to vary when such soldering is performed by a dip method and a new problem occurs that the state of contact becomes unstable at the portion where the solder height is low.
SUMMARY OF THE INVENTION
In view of the conventional art as described, it is an object of the present invention to provide a terminal connecting structure of a flexible board and a printed circuit board which is inexpensive and securely makes connection.
The present invention achieves the above object by setting the width dimension of each land portion of a copper foil pattern provided on the printed circuit board to 0.6 mm or less, previously adhering solder to these land portions and pressure-bonding each connecting portion provided on the flexible board to the solder of said land portion.
Further, in the above construction, the land portions of said printed circuit board are arranged in a zigzag pattern.
As a result of a study on the cause of dispersion in the height dimension of the solder which has been dip-soldered to each land portion, the present inventors have found that the height dimension of the solder is greatly varied by the width dimension of the land portion and have decided to set the width dimension of each land to 0.6 mm or less and preferably to about 0.4 mm. When, as described, solder is applied by means of a dip method to a thin land portion having a width dimension of 0.6 mm or less, dispersion in the height dimension among the solders becomes less, though the solder height becomes smaller due to the fact that the adhered amount of the solder is reduced. As a result, the solder height to be applied to each land portion of the printed circuit board is uniform and each terminal on the flexible board may be securely pressed into contact with respective solder at a high contacting pressure.
REFERENCES:
patent: 4466184 (1984-08-01), Cuneo et al.
patent: 5192214 (1993-03-01), Samarov et al.
patent: 62-76477 (1987-05-01), None
patent: 1-204374 (1989-08-01), None
patent: 5-166576 (1993-07-01), None
patent: 5-206627 (1993-08-01), None
“High Density Field Replaceable Flexible Circuit Connector” IBM Technical Disclosure Bulletin, Aug. 1991 vol. 34, No. 3 pp. 153-155.
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Paladini Albert W.
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