JPS61168990A - 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 (Field of Industrial Application) The present invention relates to a printed circuit board for realizing high-density packaging in electronic equipment such as a VTR.

(Conventional technology) In recent years, as home electronic devices such as audio and video equipment have rapidly become smaller, small electronic components such as ICs, chip resistors, and chip capacitors have been developed. The challenge is how to compactly mount the circuit and realize miniaturization of the device. A conventional example of a circuit mounting wiring board and a mounting method for realizing miniaturization of these devices will be described.

4(a) and 4(b) are a plan view and a side view, respectively, of a conventional circuit mounting wiring board, and FIG. 5 is a sectional view showing a conventional mounting method. In FIG. 4, 1 is an insulating layer having flexibility such as polyimide, 2 is a conductive layer coated with an adhesive, 3 is a flexible wiring board in which the insulating layer 1 and the conductive layer 2 are pressed together, and 4 is the flexible wiring board 3. Reinforcing plate to fix, 5
is an adhesive layer that joins the flexible wiring board 3 and the reinforcing board 4;
6 is a printed circuit board composed of an insulating layer 1, a conductive layer 2, a wiring board 3, a reinforcing plate 4, and an adhesive layer 5.

As shown in Figure 5, as a method for increasing the packaging density of one circuit, as seen in silicon chip ICs (integrated circuits),
Efforts are being made to increase the density of small electronic components on a flat silicon chip, but in the case of electronic devices, overall miniaturization is achieved through three-dimensional mounting rather than flat mounting. We are trying to Therefore, when mounting circuit boards, higher density can be achieved by vertically mounting them, rather than flatly mounting them. As a mounting method in this vertical direction, folding the circuit board is commonly used. In order to make this bending possible, a flexible wiring board 3 having a structure as shown in FIG. form a circuit with two signal processing functions. A plurality of these circuits are arranged on a single flexible wiring board 3 and connected together.
one unit. Reinforcement board 4 is flexible wiring board 3
This is a reinforcing member for mounting components on the board, and as shown in FIG. 5, it was used as a reinforcing member for folding and mounting. This reinforcing member is separated into two parts for bending, and the distance between them must be at least twice the thickness of the circuit board 6 in order to reduce stress on the flexible wiring board during bending. Furthermore, in order to maintain bendability and strength, the connections between the circuits on the wiring board 3 need to have bent portions formed in a parallel pattern in a direction perpendicular to the bending. By performing the folding mounting shown in FIG. 5 in this manner, components are mounted on both sides of the fold, and the height direction is effectively utilized, so that the mounting density is improved.

(Problems to be Solved by the Invention) In the conventional configuration as described above, (1) the necessity of bending and mounting makes the circuit board expensive due to the use of expensive materials such as polyimide;

(2) In the manufacturing process of a circuit board, there are many bonding steps such as bonding polyimide and a conductive layer, and bonding a polyimide wiring board and a reinforcing plate, and the process becomes complicated accordingly.

(3) Since the etched flexible wiring board and the reinforcing plate cannot be attached at the same time as described above, this is a post-process. For this reason, the outer shape of the reinforcing plate and the outer shape of the flexible wiring board must be precisely aligned, making the work difficult.

Due to the above reasons, the circuit board is expensive as a whole.

(Means for Solving the Problems) In order to solve the above problems, the printed circuit board of the present invention has a flexible adhesive layer formed on an insulating material such as epoxy to a uniform thickness of 20μ or more. A portion of the insulating material of the circuit board, on which the conductive layer of the circuit pattern is formed, is removed in a tabular shape.

It has a configuration that enables folding and mounting around Taber bending.

(Example) A printed circuit board according to an example of the present invention will be described based on FIGS. 1 to 3. Figure 1(a), (
b) is a plan view and a side view, respectively, showing the structure of a printed circuit board that is an embodiment of the present invention. In the figure, 11 is a hard insulating substrate such as paper phenol or epoxy;
2 is a tapered groove provided in the hard insulating substrate 11; 13 is a conductive material that can be etched, such as a copper thin film; and 14 is B, which is flexible enough to withstand bending when joining the conductive material and the hard insulating substrate.
An adhesive layer 15 is made of a T resin-based soft adhesive, a hard insulating substrate 11, a tapered groove 12, a conductor 13. A printed circuit board composed of an adhesive layer 14, 16 terminals at both ends of the circuit,
17 is a parallel pattern connecting the circuits.

In the printed circuit board having the above configuration, the bonding process in the manufacturing process involves applying the adhesive 14 to the insulating substrate 1.
1. Alternatively, the materials applied to the conductor 13 are combined and bonded together by applying pressure. A circuit board can be completed in one step. The conductor 13 of the printed circuit board 15 is partially removed by photoetching to form a circuit pattern. Chip resistor and chip capacitor are included in this circuit pattern.

Electronic components such as ICs are mounted to form a circuit that processes one electrical signal. A plurality of such circuits are arranged on one printed circuit board 15 and organically combined to form a functional circuit having one function. In addition, main P plates 18 are provided at both ends of the printed circuit board 15 as shown in FIG.
A terminal portion 16 for transmitting and receiving signals is formed in order to fold and mount the circuit board and connect it to the main board by soldering to operate the circuit function.

Further, the connection between the circuits is achieved by etching the conductor 13 at the bent portion of the circuit board 15 and leaving a parallel pattern 17.
Let's do it. Since the adhesive layer 14 is not removed by etching the conductor 13, it forms a protective film that covers the hard insulator even after the conductor is removed and protects the etched conductor from external stresses such as twisting. Moreover, since the material is a flexible BT resin material, when the hard insulating substrate 11 is bent, the adhesive remains on the hard insulating substrate 11.

It is possible to prevent bending stress from being applied directly to the conductor and realize bending as a circuit board 15. The hard insulating substrate 11 serves as a reinforcing member for the conductor 13. Furthermore, the tapered groove 12 provided in the hard insulating substrate 11 allows the circuit board 15 to be bent and mounted around the tapered groove 12 with little force. The tapered groove 12 is provided in the center of the circuit board 15 so as to cross the parallel pattern 17, thereby reducing stress on the parallel pattern 17 during bending and matching the terminal heights of the circuit board 15. Furthermore, by increasing the number of tapered grooves 12 in the hard insulating substrate 11, as shown in FIG.
, as shown in (b), the bending curvature per taper becomes smaller.

Stress on the conductor due to bending can be reduced. Further, similar effects can be obtained even if post-processing is performed for tapered groove processing.

As described above, according to this embodiment, a conductor is provided on an insulating substrate with a tapered groove through a flexible adhesive layer, thereby making it possible to use a flexible wiring board made of expensive polyimide or the like. It is possible to perform folding mounting without any bending, and to enable high-density circuit mounting. - (Effects of the Invention) According to the present invention, compared to a circuit board using polyimide wiring for bending a rigid printed board.

There is no need to attach a reinforcing plate, which simplifies the manufacturing process, and the tapered grooves provided on the insulating board and flexible adhesive layer allow the rigid board to be bent and mounted, reducing the cost of the circuit board. It has excellent practical effects.

[Brief explanation of drawings]

1(a) and 1(b) are respectively a plan view and a side view of a printed circuit board according to an embodiment of the present invention, and FIG.
A cross-sectional view of the circuit board mounting method of the present invention, FIG.
) are respectively a plan view and a side view of a conventional printed circuit board, and FIG. S is a sectional view of a conventional printed circuit board mounting method. 1... Insulating layer, 2... Conductive layer, 3... Flexible wiring board, 4... Reinforcement plate, 5.14...
Adhesive layer, 6.15... Printed circuit board, 11...
Rigid insulating substrate, 12... Taber groove, 13... Conductor, 16... Terminal portion, 17... Parallel pattern, 18...
...Main P board. Patent applicant Matsushita Electric Industrial Co., Ltd. Fig. 1 14-11 (Shoulder Fig. 2 18- Main Pffi Fig. 4 (a) 0gu- (V')gu-

Claims (1)

[Claims] In a single-sided or double-sided printed circuit board in which a conductor is pressure-bonded to a hard insulating substrate via an adhesive layer and a circuit network pattern is formed by etching the conductive layer on the surface, the adhesive is made of a flexible material. A printed circuit board characterized in that at least one tapered groove is formed in a direction that crosses the parallel linear pattern on an insulating substrate that is on the back side of the parallel linear pattern portion formed and arranged for electrical connection of the circuit network. .