JPH02148793A - Manufacture of printed wiring board - Google Patents

Abstract

PURPOSE:To improve electrical, mechanical strengths of conductive paste to a circuit terminal by covering with conductive ink through a coating layer of resin ink formed on part of the terminal face of a circuit terminal of a printed circuit board to form a circuit. CONSTITUTION:When other circuit 4 such as a jumper, etc. is formed on the terminal 1 of a printed circuit 10 formed on the upper side of an insulating board 20, the surface of the terminal 1 is covered with a coating layer 2 covered with a plurality of bumps 2a in multiple spot state by means such as printing, etc., with resin ink prior to the formation of the circuit 4. As the resin ink, resin ink in which a conductive material in the composition of conductive paste is removed is employed. Thereafter, the circuit 4 is printed with the conductive ink through the coating layer 2, and cured to connect a terminal 4a to the terminal 1. Thus, it can prevent the conductive paste from peeling at the jack to improve electrical, mechanical strengths.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to printed wiring boards, and in particular, connects other circuit parts such as jumper circuits to the connecting land parts of printed wiring circuits formed on an insulating substrate using copper. The present invention relates to a printed wiring board formed by applying conductive ink such as paste.

Conventional printed wiring boards are manufactured by forming the required printed wiring circuit by etching the copper foil of a so-called copper-clad laminate in which copper foil is stretched over an insulating substrate according to the required circuit. .

In addition, when forming a circuit such as a jumper circuit between the printed wiring circuits on such a printed wiring board, as shown in FIG. A manufacturing method has been developed and implemented in which the connected jumper circuit section 4 is formed by applying conductive ink made of copper paste or other conductive paste by means such as silk printing and curing it. Various conductive inks that are effective in forming this type of circuit have also been developed.

However, when forming a circuit by applying a conductive paste such as copper paste or by silk printing, a problem arises in the adhesion between the circuit terminal portion 1 of the copper foil on the printed wiring board and the conductive paste, that is, ink. .

In other words, the conductive paste contains carbon, carbon, etc. to improve conductivity.
Because a large amount of conductive substances such as copper particles are mixed into the resin ink, there is less resin that affects the adhesion to the copper foil terminal surface, and the adhesion to metal surfaces is lower than that of ordinary resin inks. This has serious drawbacks, such as not only the electrical connection force becoming unstable, but also the mechanical strength being weak and peeling due to thermal shock during soldering of parts.

Therefore, an object of the present invention is to provide a printed wiring board that can improve the electrical and mechanical strength between the conductive paste and the circuit terminal portion.

The printed wiring board of the present invention for i7° is absolutely perfect! ! In a printed wiring board consisting of a printed wiring circuit formed on a substrate and a connection circuit such as a jumper circuit formed by depositing conductive ink such as copper paste on the circuit terminal portion of the printed wiring circuit, the above-mentioned Consisting of a coating layer in which a part of the terminal surface of the circuit terminal portion of the printed wiring circuit is coated with resin ink, and a connection circuit for the circuit terminal portion of the printed wiring circuit formed by coating the coating layer with conductive ink. It is characterized by

According to the printed wiring board of the present invention, a coating layer made of resin ink is formed on a part of the terminal surface of the circuit terminal portion of the printed wiring circuit of the printed wiring board prior to forming the circuit with conductive ink. By forming a circuit using the conductive ink through the coated layer 119, the resin ink coating layer formed on a part of the terminal surface can provide an adhesion effect due to its compatibility with the conductive ink. Electrical contact between the terminal surface and the circuit section made of conductive ink.

Mechanical strength can be improved.

1 Difference ■ An embodiment of the printed wiring board of the present invention will be described with reference to the drawings.

(First Embodiment) FIGS. 1 and 2 show a first embodiment of the printed wiring board of the present invention. FIG. FIG. 2a is an enlarged plan view showing a state in which a jumper circuit is connected to the terminal portion, and FIG. 2a is a sectional view taken along line AA of FIG. 2a.

As shown in FIGS. 1 and 2, in the printed wiring board of the present invention, another circuit, for example, a jumper circuit 4 is formed on the terminal portion 1 of the printed wiring circuit 10 formed on the upper side of the insulating substrate 20. In this case, as shown in FIG. 1, prior to forming the jumper circuit 4, the surface of the terminal portion 1 is coated with resin ink, for example, the composition of the conductive paste used for forming the jumper circuit 4. Using a resin ink having the same composition as the resin ink except for the conductive material, a coating layer 2 having a plurality of protrusions 2a adhered at multiple points is formed by means such as printing.

After that, jumper circuit 4 is printed using conductive ink.
By printing and curing this, a jumper circuit 4 in which the terminal portion 4a is electrically connected to the terminal portion l can be formed.

Further, the jumper circuit 4 is protected by covering it with an insulating overcoat 5.

Furthermore, when forming the jumper circuit 4 on the printed wiring board 21, insulating film Fl! Needless to say, it is formed after the film (not shown) is deposited.

Therefore, the insulating resin ink is usually applied at the same time as the formation of the insulating film to be applied to the upper side of the printed wiring circuit 10, which is performed prior to the formation of circuits such as the jumper circuit 4, that is, at the time of forming the insulating film. At the same time as silk printing, an increase in the number of steps can be prevented by printing the coating layer 2 that covers the protrusions 2a in multiple points on the terminal surface of the terminal portion 1. However, regarding the resin ink at this time, the protrusions 2a are naturally formed using the same resin ink as the insulating coating.

The coating layer 2 of the terminal portion 1 has a structure in which a plurality of protrusions 2a are attached to the terminal surface so that the terminal surface is partially covered and the other surface is exposed.

As is clear from the above examples, according to the printed wiring board of this example, when forming circuits such as the necessary jumper circuit 4 after forming the printed wiring circuit 10, ordinary resin ink is conductive even to metal surfaces. Utilizing the property of having excellent adhesion even to conductive ink, a part of the terminal surface of the terminal part l is coated with resin ink, and then conductive ink is coated to form circuits such as the jumper circuit 4. It is something to do.

(Second Embodiment) Figs. 3 and 4 show a second embodiment of the printed wiring board of the present invention, in which Fig. 3 is an enlarged plan view of the terminal section, and Fig. 4a shows a jumper circuit in the terminal section. FIG. 4 is an enlarged plan view of the state in which the structure is formed, and FIG. 4 is a sectional view taken along the line BB in FIG. 4a.

The method for manufacturing a printed wiring board according to the second embodiment includes forming a mesh 3a-shaped coating layer 3 on the terminal surface of the terminal portion 1 of the printed wiring circuit 10, in place of the multi-point coating layer 2 of the first embodiment. It is formed by applying resin ink by means such as silk printing.

Thereafter, the jumper circuit 4 is formed by the same method as in the first embodiment.

Since the other manufacturing methods are completely the same as those in the first embodiment, the same components are given the same numbers and the explanation thereof will be omitted.

According to the printed wiring board of the present invention, resin ink is applied to the terminal surface of the printed wiring circuit in the form of strings or multi-dots, and then jumper circuits etc. are coated with conductive ink on the terminal surface of the printed wiring circuit. By depositing and forming the circuit, it is possible to prevent separation between the terminal surface and the conductive paste at the circuit connection portion such as a jumper circuit, and to reliably prevent the occurrence of defects in the printed wiring board.

[Brief explanation of the drawing]

1 and 2 show a first embodiment of the printed wiring board of the present invention, and FIG. 1 shows a state in which a multi-dot coating layer is provided with resin ink on the terminal surface of a terminal portion in a printed wiring circuit. An enlarged plan view, Fig. 2a is an enlarged plan view showing a state in which a jumper circuit is connected to the terminal part to form a temperature, Fig. 2 is a sectional view taken along line AA of Fig. 2a, Figs. 3 and 4 3 shows a second embodiment of the printed wiring board of the present invention, FIG. 3 is an enlarged plan view of the terminal portion, FIG. is a sectional view taken along the line B--B in FIG. 4a, and FIG. 5 is a partially enlarged view showing the connection between the conventional terminal surface and a jumper circuit using conductive ink. 1...Terminal portion 2.3...Coating layer made of resin ink 4...Jumper circuit 10 formed of conductive paste...Printed wiring circuit 20...Insulating substrate 21...Overcoat film

Claims (3)

[Claims] 1. In a printed wiring board consisting of a printed wiring circuit formed on an insulating substrate and a connection circuit such as a jumper circuit formed by coating the circuit terminal part of the printed wiring circuit with conductive ink such as copper paste, A coating layer in which a part of the terminal surface of the circuit terminal portion of the printed wiring circuit is coated with resin ink, and a connection circuit of the circuit terminal portion of the printed wiring circuit formed by coating the coating layer with conductive ink. A printed wiring board characterized by: 2. 2. The printed wiring board according to claim 1, wherein the coating layer on the terminal surface of the circuit terminal portion is formed by applying resin ink in a halftone dot pattern. 3. 2. The method of manufacturing a printed wiring board according to claim 1, wherein the coating layer on the terminal surface of the circuit terminal portion is formed by applying resin ink in multiple points.