JPH07212036A - Circuit connection method by ultrasonic fusion - Google Patents

Abstract

PURPOSE:To enable two circuits each printed on a thermoplastic film with conductive ink to be easily and surely connected together in a short time by a method wherein the connection parts of the circuits printed on the films are made to confront each other, a horn provided with irregularities arranged at a specific pitch is made to bear against either of the circuit films, a plane pad jig is pressed against the other circuit film, and the circuits are connected together by ultrasonic fusion bonding. CONSTITUTION:By the use of a latticed pattern of pitch 0.4mm or above, a conductive ink circuit printed on a film is made to come into contact with another conductive ink circuit printed on another film in a latticed pattern, so that the molten conductive ink of the other circuit is relieved to flow out through the latticed pattern, and the bonding spots of the two circuits are firmly fusion-bonded together. By the above circuit bonding method, the circuit of a circuit sheet 3 can be connected to a bonding spot 10 of the other circuit of another circuit sheet to constitute a circuit through a simple manner, and furthermore the peripheries of circuit sheets are fusion-bonded together by an ultrasonic bonding method at the same time when circuits are connected together, whereby the circuit sheets can be fixed together.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for connecting electrical circuits formed of conductive ink on a thermoplastic film.

[0002]

2. Description of the Related Art A conventional circuit printed with a conductive ink on a thermoplastic film is inferior in heat resistance and therefore not suitable for soldering. Are sandwiched for heat-welding connection, or the connection portions are polymerized and fixed with screws, an adhesive or the like.

[0003]

In the conventional method using an anisotropic conductive film, it takes a long time for pressure bonding and fixation, and the latter screw,
Fixing with an adhesive requires a labor for aligning the connecting portions with each other, often results in an unstable connection, and also increases the cost of the fixing member.

[0004]

SUMMARY OF THE INVENTION Therefore, the present invention provides a horn or a planar horn having circuits formed of conductive ink on a thermoplastic film, which are opposed to each other, and which has convex and concave projections such as a lattice on one side, and On the other side, a flat receiving jig or a jig having an uneven projection surface such as a lattice is arranged, and the two circuits are connected by ultrasonic welding.

It is desirable that the uneven horn used here or the receiving jig has an uneven pitch of 0.4 mm or more. If the uneven pattern pitch is less than this, the conductive ink at the welded portion may flow and the conduction may become unstable.

[0006]

The present invention will be described below with reference to the embodiments shown in the drawings.

An upper circuit 2 printed with conductive ink on the thermoplastic film 1 and a lower circuit 4 similarly printed with conductive ink on the thermoplastic film 3 face each other with a spacer 5 therebetween. . The pitch of 0.
A horn 6 having a grid pattern of 4 mm or more at its tip is arranged, a flat receiving jig is arranged under the lower circuit, and ultrasonic waves are applied to the two circuits for welding and connection. FIG. 2 shows the state after the welding connection.

By using a horn having a grid pattern of 0.4 mm or more, one conductive ink circuit portion comes into grid contact with the other conductive ink circuit portion during ultrasonic welding, and the other conductive ink circuit portion contacts the other conductive ink circuit portion. A space for escape of the melted conductive ink in the circuit portion is secured, and both circuit portions at the welding point can be sufficiently welded and fixed. If there is no escape space,
In some cases, the melted ink may flow and the welding may become insufficient, resulting in unstable conduction. FIG. 3 shows one circuit sheet as a whole, and a conventional circuit sheet is shown in FIG. 3A. In the case of this conventional circuit, the folding side 9 of the thermoplastic film 8 is shown.
Although the circuit is drawn up to this point, the circuit sheet 3 according to the circuit connecting method of the present invention shown in FIG. 7B enables welding connection with other circuits at the center of the circuit sheet (welding portion 10), and The circuit configuration can be simplified, and by connecting the circuit sheet and ultrasonic welding at the same time as the circuit connection, both circuit sheets can be connected and fixed at the same time.

[0009]

According to the connection method of the present invention, both circuits can be connected easily and reliably in a short time.

Further, there is no need for a member such as an anisotropic conductive film, a screw, an adhesive agent, etc., and the material cost can be reduced.

Furthermore, since the periphery of the circuit sheet is also welded at the same time as the circuit connecting portion is welded, it is possible to omit the time and effort required to adhere both circuit sheets using a double-sided adhesive tape or the like.

[Brief description of drawings]

FIG. 1 Sectional view

FIG. 2 is a sectional view during welding.

FIG. 3 is a plan view showing the entire circuit sheet, FIG. 3A showing a conventional sheet and FIG. 3B showing a sheet according to the present invention.

[Explanation of symbols]

 1,3 Thermoplastic film 2,4 Circuit part 5 Spacer 6 Lattice horn 7 Plane receiving jig 8 Thermoplastic film 9 Bending part

Claims (2)

[Claims] 1. In a circuit printed with a conductive ink on a thermoplastic film, the connecting portions of both circuits are made to face each other,
A horn or a receiving jig having a concavo-convex pattern with a pitch of 0.4 mm or more on the tip surface is arranged on one side, and a flat receiving jig or horn is arranged on the other side to connect a circuit by ultrasonic welding. Method. 2. The circuit connecting method by ultrasonic welding according to claim 1, wherein the uneven pattern is a grid pattern.