JPS6242548Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a circuit board on which electrical circuit elements can be mounted at high density.

Conventionally, circuit boards, such as alumina boards, are made by mounting conductors in a predetermined pattern on an insulating board.
Printed circuit boards made of phenol, epoxy resin, etc., made by applying Ag paste in a predetermined pattern and baking them, or etching copper foil into a predetermined pattern, are used for electrical circuit elements (chip parts such as resistors, capacitors, transistors, etc.). )
is generally mounted only on one side of the board.

In order to improve packaging density, a method is used in which chip components are mounted and soldered on both sides of a double-sided wiring board, but in this case, soldering must be performed on each side, and both sides must be soldered at the same time. When attaching chips, it is necessary to fix the chip parts mounted on one of the main planes of the board with adhesive, etc., which makes the work complicated, reduces production efficiency, and reduces material costs. It had problems such as being expensive.

The present invention provides a circuit board that solves the above problems, and will be described below with reference to drawings shown as embodiments.

A substrate 100 shown in FIG. 1 is an example of a member constituting the circuit board of the present invention, and this is a film-like or thin-plate-like substrate 1 made of a flexible insulator.
A conductor 2 is arranged in a predetermined pattern on one main plane (surface) of the circuit element 4 (for example, a resistor, a capacitor, a transistor, (such as chip parts) are mounted on a tower by soldering or adhesively fixing them with a conductive adhesive such as Ag paste.

Base plates 3R and 3L are bonded to the other main plane (back surface) of the substrate 1 at a predetermined interval G in the center to facilitate mounting of a clip-type lead frame 5, which will be described later. Above base plate 3R, 3L
It is possible to use a phenolic resin substrate having some degree of rigidity, other plastic plates, or thin metal plates such as Al or the like laminated in a predetermined manner and bonded together.

FIG. 2 is a cross-sectional view of the board 100 shown in FIG. 1 taken along the line S-S. Clip-shaped lead frames 5 each having a U-shaped tip are attached to both ends of the board 100 shown in FIG. are mounted so as to sandwich the base plates 3R, 3L and the substrate 1.

In the embodiment of the present invention, the same number of lead frames as the number of conductors 2 are arranged at the arrangement pitch P, and the number of conductors 2 is
A total of eight lead frames 5 are mounted at four locations corresponding to the positions of.

Thereafter, the conductor 2 and the lead frame 5 are electrically connected to each other using solder or a conductive adhesive such as Ag paste.

Note that the board 100 on which the lead frame 6 is mounted
A plurality of notches 7 having a width W are provided at predetermined pitches (P) at predetermined positions on both end portions of the cutout 7 at predetermined cutting depths.

In the embodiment shown in FIG. 1, the same number of notches 7 as the number of lead frames 5 to be mounted are arranged in four locations at each end of the substrate 100 in a staggered manner close to the conductor 2. Specifically, it is provided at the end of the board on the opposite side to the lead frame mounting side, corresponding to the position of the bent portion 5A of the lead frame 5 mounted on both ends of the board 100. The reason for providing the notch 7 is as follows. That is, the bent portion 5A of the lead frame 5 is connected to the substrate 1 as shown in FIG.
Located on the back side of 00. Therefore, as will be described later, if the substrate 100 is bent at the center or approximately at the center so that the back surfaces thereof face each other, and the back surfaces of the substrates are bonded together to integrate them, the leads attached to the ends of the substrate Since the bent portion 5A of the frame is located on the back surface of the substrate, the back surfaces of the bent substrates cannot be closely stacked on top of each other, which causes inconvenience in the substrate bonding process and the like. Furthermore, the overlapping thickness dimension t (see FIG. 3) cannot be configured to be small. This does not satisfy the requirements for making the circuit board smaller and thinner, and requires a lot of man-hours to bend and attach the board 100, making the manufacturing equipment complicated.

Next, the substrate 100 configured as described above is placed in a third
The procedure for constructing the shape shown in the figure will be explained.
As shown in FIG. 2, the board 100 with the lead frame 5 attached is bent in the directions of arrows A and A' at the center of the flexible board 1, and as shown in FIG. Base plate 3
Fold R and 3L so that they are in close contact with each other.

Although not shown, the base plates 3R, 3L
An adhesive member is applied in advance to one of the main surfaces of the substrate 100 in a predetermined manner, and after the substrate 100 is folded as shown in FIG. It is glued and fixed.

In this way, one board 100 is placed in the center or
By bending and adhering at approximately the center, it is possible to obtain the same effect as when circuit elements are mounted on both sides of the board.

Note that as the adhesive member for bonding the base plates 3R and 3L together, any member such as an epoxy resin-based liquid member, instant adhesive, double-sided adhesive tape, or prepreg resin may be used. Furthermore, the adhesive member may be applied after the substrates 100 are bent and laminated.

When the substrate 100 is bent and bonded as shown in FIG. 3, the lead frames 5 attached to the ends of the substrate 100 are placed facing each other (so-called dual in-line type).

Thereafter, if necessary, the substrate 100 and the circuit element 4 are coated with an epoxy resin or the like to a predetermined thickness, thereby completing the intended electric circuit board.

As mentioned above, the present invention allows circuit elements to be mounted on both sides of a double-sided wiring board by bending a flexible board with conductors and circuit elements mounted on one side so that the back faces face each other. It is possible to obtain the same effects as in the case of the present invention, and it is also possible to obtain effects such as improvement in packaging density and productivity.

It goes without saying that the clip shape and lead shape of the clip-type lead frame used in the embodiments of the present invention may be of any arbitrary shape, and there are no limitations on the mounting procedure of the clip-type lead frame. isn't it.

Furthermore, the shape and position of the notch formed at the end of the board may be arbitrary, and instead of the notch, a recess may be provided in the base plate so that it does not come into contact with the bent portion 5A of the lead frame. . Also,
It is also optional whether or not to adhere a base plate to the back surface of the flexible substrate in advance.

[Brief explanation of the drawing]

Figure 1 is a perspective view of an example of a flexible circuit board used in the present invention, and Figure 2 is a cross-sectional view of Figure 1.
FIG. 3 is a cross-sectional view taken along a line, and a side view showing an embodiment of the circuit board of the present invention. 1...Flexible substrate, 2...Conductor, 3
R, 3L... Base plate, 4... Circuit element, 5... Lead frame, 5A... Bent portion, 7... Notch, 100... Circuit board.

Claims (1)

[Claims for Utility Model Registration] (1) Conductors and circuit elements in a predetermined pattern are attached to the front surface, a base plate is glued to the back surface with a predetermined distance in the center, and the opposing ends are A flexible board consisting of a required number of clip-shaped lead frames arranged so as to hold the ends thereof is folded at the center or approximately at the center so that the back sides thereof face each other and the lead frames form a dual in-line. bending, and integrally joining the back surfaces of the bent substrates, and providing a recess or a notch at a predetermined position of the substrate so that the clip portion of the lead frame does not come into contact with the back surface of the opposing substrate. A circuit board characterized by: (2) In the statement of claim 1 of the utility model registration claim, base plates of a predetermined thickness are adhered to the back surfaces of the substrates, and the back surfaces of the substrates are integrally bonded to each other via these base plates. A circuit board characterized by being bonded to.