JPS5917295A - Printed circuit board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a printed wiring in which a resistor is constructed by printing and coating a member such as carbon paste between both terminals on a substrate, and a reinforcing overcoat material is coated on top of the resistor. This relates to improvements to substrates.

As mentioned above, a method of forming a resistor on a substrate by printing and applying a material such as carbon paste has recently been attracting attention.

Fig. 1 shows a conventional printed wiring board of this kind provided with the printed resistor, in which carbon paste or the like is applied by printing method between a pair of terminals 2 and 2' patterned on the board 1. a resistor 3 and a terminal 2.2';
An overcoat resist 4 is printed on the surface of the resistor 3 to protect and reinforce the resistor 3.

However, once the overcoat resist is printed, it is difficult to peel it off, so if the overcoat resist 4 is printed to the entire surface of the terminal 2, 2' as in the above conventional method, the resistor 3 will be damaged. The disadvantage is that even if a problem occurs, it cannot be easily repaired.

In view of such conventional drawbacks, the present invention provides that even if a defect occurs in a resistor, it can be easily repaired by using the terminals of the resistor to reinstall a printed resistor with carbon paste, or by installing a chip resistor. The purpose of the present invention is to provide a printed wiring board that enables the following.

The present invention will be explained in detail below based on the drawings.

FIG. 2 is a diagram showing a printed wiring board according to the present invention, in which carbon paste (carbon powder mixed with epoxy or phenolic resin) is printed and coated between terminals 2 and 2' to form a resistor 3. The procedure for printing and applying overcoat resist 4 (epoxy resin) on this board is the same, but especially for this board, terminals 2 and 2' are formed in a large rectangular pattern as shown in the figure, and this pattern is A part of the formed terminal 2.2', that is, a part of the terminal 2.2' at the connection part between the resistor 3 and the resistor 3, is coated with an overcoat resist 4, leaving a part of the terminal 2.2' apart from the resistor 3. It is characterized by the covered area.

In this way, if the overcoat resist 4 is printed and coated on the entire overcoat resist 4 while leaving a part of the terminal 2.2', even if a defect occurs in the resistor 3, both terminals 2.2' (7) of the resistor
Since some parts of the terminals 2 and 2' are not covered with the overcoat resist 4, carbon paste is applied again on the overcoat resist 4 as shown in FIG. This can be easily repaired by forming a new resistor 3' and then applying an overcoat resist 41 thereon.

In the above embodiment, a new resistor was formed by applying carbon paste again for repair, but a chip resistor may be connected instead.

As described above, the printed wiring board of the present invention has both terminals 2.2'
Since a part of each is exposed, the resistor can be easily repaired using that part.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a conventional board, FIG. 2 is a diagram showing a printed wiring board according to the present invention, and FIG. 3 is a diagram showing an example of repair on the same board.

Claims (1)

[Claims] 1. In a resistor formed by printing and applying a material such as carbon paste between both terminals on a board, and applying an overcoat material thereon, the overcoat material is applied between both terminals. 1. A printed wiring board characterized in that the printed wiring board is coated by leaving each part intact.