JPS5914694A - Printed 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 relates to a printed circuit board using a metal plate as a base member, in which a component having leads can be reliably soldered to a copper foil pattern without the leads coming into contact with the metal base member. It has been made possible.

In recent years, printed circuit boards that use metal plates as base members have begun to be developed. FIG. 1 is a sectional view of a printed circuit board using this metal plate as a base member.

Here, 1 is a metal base member, 2 is an adhesive layer that also serves as insulation, and 3 is a copper foil pattern.

When drilling holes in such a printed circuit board using a normal method, the metal base member 1 is damaged because the insulating layer 2 is thin, as shown in FIG. and the copper foil pattern 3 come into contact and are electrically connected. In order to solve this problem, conventionally, the insulating layer 2 and the copper foil pattern 3 are formed from a portion set back from the edge of the hole 7 by a distance υ, as shown in the side B of FIG.

When a component with leads is inserted and soldered to this printed circuit board □ in the same way as in the case of a normal printed circuit board based on an insulating material, the lead 4 is attached to the metal base member as shown in Fig. 1 may come into contact with (
Also, due to the existence of the above-mentioned distance a, the solder 5 also comes into contact with the metal base part 1 (mouth part), and as a result, the copper foil pattern 3 and the metal base member 1 end up contacting each other as in the case of FIG. It is electrically connected. Therefore,
Normally, as shown in FIG. 4, components with leads are not used, but lead wire components 6 are used, and the electrodes at both ends are connected to the copper foil pattern 3 with solder 5. The present invention was developed in view of the above problems. , it is possible to solder components having leads to this type of printed circuit board while maintaining the necessary insulation state.

The present invention attempts to achieve insulation using insulating ink. In particular, normally, a solder resist is applied to the copper foil pattern surface, and a road map indicating the parts to be installed is applied to the component mounting surface. Since the resist and road map materials are insulative, at least one of them is used to apply the insulating paint between the copper foil pattern and the vertical end face of the insulating layer and to the inner wall of the hole to form the leads of the component. This eliminates electrical connections between the copper foil pattern and the metal base member, and further between the copper foil pattern and the metal base member.

One implementation will be described below with reference to FIGS. 6 and 7. FIG. 6 shows a printed circuit board with a hole diameter of C, when printing resist ink 8 on the side where the copper foil pattern 3 is formed and road map ink 9 on the component mounting side.
Resist ink 8 and road map ink 9 are positioned in the hole T so that the surface ink 8 and 9 enters the hole T, and the resist ink 8 is positioned between the vertical end faces of the copper foil pattern 3 and the insulating layer 2. Then, the resist ink 8 and the road map ink 9 are applied to the inner wall of the hole 7. As a result, although bubbles are formed between the resist ink 8 and the road map ink 9, the holes are blocked by the resist ink 8 and the road map ink 9. After this, the lead of the component is inserted directly into the hole by piercing through the center part where it is thinnest, or by using another jig, and then inserted into the hole, as shown in Figure 7. The tip of the lead 4 protruding from the foil pattern surface is fixed to the copper foil pattern 3 with solder 6. According to this configuration, since the resist ink 8 and the road map ink 9 are present between the inner wall of the hole 7 and the vertical end face of the copper active turn 3 and the insulating layer 2, the leads 4 are prevented from coming into contact with the metal base member 1. Moreover, the solder 5 does not come into contact with the metal base member 1, and a reliable insulation state can be obtained.

FIG. 6 shows an example in which the hole diameter e is larger than the hole diameter C in FIG. In comparison, lead insertion can be performed smoothly. of course,
The same effect as in the case of FIG. 5 can be obtained.

Furthermore, as another example, it is conceivable to use only one of the resist ink 8 and the road map ink 9 for insulation.

In this case, since insulation must also be provided between the vertical end faces of the insulating layer 2 and the copper foil pattern 3, it is desirable to use the resist ink 8, but of course the road map ink 9 may also be used. When applying these insulating inks, it is conceivable that the ink is not applied to the entire surface of the inner wall of the hole. Although it is conceivable that the metal surface may be exposed especially in the central portion of the hole, the insulation between the lead 4 and the inner wall of the hole is maintained because the lead 4 is positioned by the presence of each of the inks 8 and 9 in the opening. Also, in the above example, the ink is applied so as to close the hole, but of course it is necessary to apply the insulating ink to the inner wall of the hole and the vertical edges of the copper foil pattern and the insulating layer so as not to block the hole. Needless to say, it is okay to do so.

As explained above, according to the present invention, a copper foil pattern is formed on at least one surface of a conductive metal base member via an insulating layer, and the copper foil pattern is formed so as to penetrate through the metal base member of the bracket, the insulating layer, and the copper foil pattern. In the board in which the holes are formed, insulating ink is applied to each vertical end face of the insulating layer and the copper foil pattern, and to the inner wall of the hole, thereby forming a gap between the lead of the component and the metal base member and between the solder and the metal base member. The leads can be soldered to the copper foil pattern after being reliably insulated with insulating ink. Furthermore, by using resin ink and road map ink as the insulating ink, each ink can be applied at the same time as the printing process, and the number of processes does not increase.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a conventional printed circuit board, Figure 2 is a cross-sectional view of the main parts of the same printed circuit board to explain the problems, and Figures 3 and 4 are the configuration and parts of other conventional printed circuit boards. 5 and 6 are cross-sectional views showing a printed circuit board in an embodiment of the present invention, and FIG. 7 is a cross-sectional view showing parts soldered to the printed circuit board. 1... Metal base part, 2... Insulating layer, 3... Copper foil pattern, 7... Hole, 8
...Resist ink, 9... Road map ink.

Claims (1)

[Scope of Claims] (1) A copper foil pattern is formed on at least one surface of a conductive metal base member via an insulating layer, and a lead is inserted so as to penetrate through the metal base member, the insulating layer, and the copper foil pattern. 1. A printed circuit board characterized in that a hole is provided and an insulating ink is applied to the inner wall for inserting the lead and to each vertical end surface of the insulating layer and the copper foil pattern. 2)) The printed circuit board according to claim 1, wherein insulating ink is applied so as to close the lead insertion hole. (3) The invention according to claim 1 or 2, wherein at least one of resist ink printed on the copper foil pattern surface and road map ink printed on the component mounting surface is used as the insulating ink. Printed board.