JPH0378793B2 - - Google Patents

Abstract

A metal core printed wiring board in which a large number of lead terminal such as of an IC or an LSI are formed by etching or the like method at an edge of at least one end of a conductive substrate that serves as a core, the core and the terminals are bonded together with an insulating bonding material maintaining electrical insulation, a conductive circuit pattern is formed directly on the surface of the insulating bonding material, or a printed board on which the wiring has been printed is adhered onto the surface of the insulating bonding material, in order to increase the density of mounting, to facilitate the connection to other circuit substrates such as mother boards, and to decrease the volume of circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a metal core wiring board, particularly to a metal core wiring board used for high-density mounting printed wiring or hybrid ICs.

(Prior art) Metal core wiring boards that have been commonly used in the past require an insulating layer to be attached to the surface of the metal plate that serves as the core, and the required conductive patterns, through holes, etc. are formed on the insulating layer, resulting in a complicated manufacturing process. However, the drawback was that the cost was also high.

In order to eliminate the above-mentioned problems in the manufacturing process of metal core wiring boards commonly used in the past, there are systems in which a flexible printed circuit board is bonded directly to the surface of the metal core and components are mounted on this printed circuit board. In this case, it is not only impossible to adopt the method of improving component mounting density by forming a circuit pattern on the back surface of the flexible printed board and connecting it to the mounted components on the surface through through holes, but also to There is a drawback in that when it is necessary to provide lead terminals, individual lead terminals must be added to the flexible printed circuit board.

(Object of the Invention) The present invention has been made in order to eliminate the defects of the conventional metal core wiring board as described above, and is suitable for high-density packaging, and has lead terminals and circuit patterns formed in advance on the periphery of the core metal. The purpose is to provide a metal core wiring board that can be easily connected.

(Summary of the Invention) In order to achieve the above-mentioned object, a metal core wiring board according to the present invention has the following configuration.

That is, a flexible printed circuit board in which lead terminals are formed on the periphery of a thin conductive plate serving as a core, the base of the lead terminals and the core body are insulatively bonded with adhesive, and printed wiring is completed on one or both sides of the core. a lead terminal base formed on the periphery of the core and the wiring pattern via the through hole of the printed circuit board, which is entirely adhered with an adhesive except for the through hole portion provided therein;
Alternatively, it may be further connected to the core body, for example, by soldering.

(Embodiments of the Invention) Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 1 is a sectional view showing a basic embodiment of a metal core wiring board according to the present invention.

That is, a lead terminal 2 is formed at a suitable location on the periphery of a thin metal plate 1 serving as the core of the board by a method such as etching, which will be described later, and an adhesive 3 is applied between the base of the lead terminal and the thin metal plate 1 serving as the core. Therefore, the flexible substrate 5, which is insulated and fixed and on which the printed pattern 4 has already been wired, is entirely adhered to the core 1 using the adhesive 3 described above. At this time, a through hole 6 is provided in the portion of the flexible printed circuit board that comes into contact with the base of the lead terminal 2 as necessary.
is provided to prevent the adhesive 3 from adhering only at this portion, and to connect the base of the lead terminal 2 and the wiring pattern 4 via the through hole 6 with solder 7.

The component 7 to be mounted is the wiring pattern 4.
The connection may be fixed using a method such as reflow.

A metal core wiring board having the structure as described above can be easily manufactured by using, for example, the following method.

The process explanatory diagram in Figure 2a is related to the A-A cross section in Figure 2b. First, a thin plate of iron, silicon steel, copper, phosphor bronze, etc. with a thickness of 0.1 to 1.0 mm is prepared as the core. A photosensitive resin or film 8 is applied or adhered to the surface, exposed to ultraviolet light using a required pattern mask, and developed to expose only desired portions of the surface of the thin metal plate. After that, a conventional method is applied. Etching is performed by etching. In this way, lead terminals 2, 2, . It is temporarily connected to the core 1 by a lead frame 9.

Next, after the photosensitive layer has been washed and removed, an adhesive 3 is printed and coated on the entire surface of the core 1 except for a required portion of the base surface of the lead terminal 2 to bond the base of the lead terminal 2 and the core 1. In addition to insulating fixation, the flexible printed circuit board 5 on which printed wiring and through-holes 6 have been previously formed as shown in a7 is bonded.

Further, the printed wiring 4 and the lead terminal 2 are electrically connected through the through hole 6 using solder or a conductive adhesive 7.

The necessary components are mounted on the metal core wiring board manufactured by the above procedure using the reflow method as described above, but the lead frame 9 may be cut and removed before or after this mounting. Needless to say.

Note that the metal core wiring board according to the present invention may be modified as follows.

That is, as shown in FIG. 3, flexible printed circuit boards 5 and 5' may be adhered to both sides of the core 1, or as shown in FIG. The lead frames 11, 11, . . . and the center portion thereof are provided with suitable perforations or groove lines in the lead frame 10 to facilitate bending, thereby making flexible prints possible on the surfaces of the left and right cores 1, 1', respectively. After bonding the substrates, the metal core double-sided substrate may be manufactured by folding back the folded portion 10 as a border. At this time, the lead frames 11, 11, . . . of the folded portion 10 connect the lead frames 9, 9' that integrally connect the lead terminals 2, 2, . The cores 1 and 1' may be made electrically independent by cutting and removing them at the same time as they are separated.

Although only the case where a general flexible wiring board is bonded onto a thin metal plate serving as a core has been described above, the present invention is not limited to this only, and rather, as shown in FIG. Concentrate the circuit pattern 4 on the through holes 6, 6,...
It is suitable for combining with the core 1 a printed circuit board on which components are mounted at high density on the surface through ..., and by doing so, high density mounting and use of the core as a large-area grounding plate can be simultaneously and easily performed. It is possible to realize this.

(Effects of the Invention) Since the metal core wiring board according to the present invention is constructed as described above, it is possible to form highly accurate lead terminals and connect these with circuit patterns extremely easily. It is extremely effective in manufacturing at low cost.

In addition, with such wiring boards, it is easy to concentrate circuit patterns on one side of the flexible printed wiring board that is adhered to the core, and to mount components on the other side via through holes, so the packaging density can be greatly increased. It is extremely convenient when constructing hybrid ICs, etc., which require improved heat dissipation and electrostatic or magnetic shielding properties.

Furthermore, since it is easy to mount components on both sides of the core, it goes without saying that it is suitable for use as a multilayer wiring board, and from this point of view as well, it is extremely effective in making electronic devices smaller and thinner.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a basic embodiment of a metal core wiring board according to the present invention, and a ₁ to a ₉ in FIG. The sectional views taken along the line AA in the plan view and FIGS. 3 to 5 are sectional views or plan views showing different embodiments of the metal core wiring board of the present invention, respectively. 1, 1'... Core (conductor thin plate), 2, 2'... Lead terminal, 3... Adhesive, 5, 5'... Flexible printed circuit board, 6... Through hole, 10...
...core folded part.

Claims (1)

[Scope of Claims] 1. Lead terminals are formed on the periphery of a thin conductive plate serving as a core, and the base of the lead terminal and the core body are insulatively bonded with adhesive, and printed wiring is completed on one or both sides of the core. The entire surface of the flexible printed circuit board except for the through hole portion provided therein is adhered with adhesive, and the wiring pattern and the terminal on the periphery of the core are connected through the through hole of the printed circuit board, or further to the core body. A metal core wiring board characterized by electrically connecting. 2. After forming a folded part suitable for bending and overlapping the metal core at a predetermined position of the metal core, and bonding printed circuit boards on both sides of the folded part on the same surface of the metal core, 2. The metal core wiring board according to claim 1, wherein the metal core wiring board is bent and overlapped at the border.