JPS5932077B2 - How to ground the metal core - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention particularly relates to a method of grounding a metal core (hereinafter referred to as a core) in the manufacturing process of a metal core printed wiring board used in an electronic circuit package on which heavy components are mounted, for example.

The intention is to improve the workability of the manufacturing processes involved and improve production capacity.

Conventional metal core printed wiring boards have superior mechanical properties as mentioned above compared to general copper-clad laminates for printed circuits, and can also form auxiliary magnetic circuits for parts equipped with magnetic circuits such as relays with cores such as iron plates. It has advantages such as water resistance, and is widely used in places where it is integrated and implemented, such as relays. The wiring board processing involves pressing a core member such as iron into an appropriate shape and size, and forming through-holes at the same time.Then, the surface of the member is coated with an epoxy or acrylic resin layer (insulating coat). ), it has obtained the necessary printed board insulation and voltage resistance functions.

Then, a copper layer is deposited on the surface of the insulating layer by electroless plating or the like, and circuit patterning is performed. However, in order to ground a specific point in the circuit pattern, conventional methods include machining a through hole to make the hole wall conductive to the metal core, or, depending on the location, inserting a tap screw of an appropriate diameter into the pre-formed through hole. It was screwed in to establish electrical continuity with the core.

An example of grounding a metal core is shown in cross-section in FIG. In the figure, 1 is a metal core, 2 is an insulating coat, and 3 is a so-called through-hole processing section, which is a land section provided for continuity between the front and back sides of the board (the holes may also be used to attach components).
, 4 is a tap screw embedded in the part for grounding, and after the screw 4 is installed, a solder bridge layer 5 is formed between the screw tip and the land conductor 3 to form a grounding circuit.

Of course, there are also grounding methods that do not use tapped screws, and in this case, grounding the metal core requires detailed work, such as tapping the hole before connecting to the ground to completely remove the insulating coat that has adhered to the inner wall of the hole. It was a situation that I cannot take lightly.
The object of the present invention is to solve the above-mentioned problems and to provide the following proposal that improves the workability of core grounding. Its feature lies in the method of grounding the metal core by providing a land around the burring part and connecting the land to the exposed metal at the end of the burring by soldering means. This will be explained below according to the process diagram of the present invention shown in FIG. In the figure, the same numbers as above indicate the same functional parts as before.

Figure A shows a hole 6 to be burred, and as shown in the figure, for example, an edge deformation part 7 of a protrusion is forcibly formed on the back side of the core plate by pressing or the like during the initial production of the core.

The diagram shows the state in which an insulating coat 2 is then applied to both surfaces of the member, and then a land portion 3 made of copper or the like as a conductive layer is additionally formed. The figure shows a state in which the insulating coat on the burring end face 8 has been removed and the core metal surface has been exposed.
The insulating coat is simply removed by sanding or by localized sandplast. Figure 2 shows the state in which the circuit forming body shown in figure C is coated with a solder resist, soldered 5 by flow soldering, etc., and the grounding connection of the metal core is completed.

According to the grounding method of the present invention, the grounding work is simpler than the conventional connection to the metal core on the hole wall surface or the connection using a tap screw, which greatly contributes to a reduction in the number of work steps.

It also has great practical effects, such as the ability to easily check the connection performance visually.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a conventional metal core grounding method, and FIG. 2 is a sectional view showing a metal core soldering grounding method according to the present invention. 1...Metal core, 2...Insulating coat,
3...Land made of copper foil, etc., 5...
・Soldering, 6...Hole to be burred.

Claims (1)

[Claims] 1. In the manufacturing process of a metal core printed wiring board, in which a metal core is burred in advance, and then an insulating coat layer and a circuit pattern formed by further adhering copper foil, etc. are sequentially formed, the area around the burring part is A method for grounding a metal core, comprising providing a land and connecting the land and exposed metal at the end of the burring by soldering means.