JPH0731556Y2 - Flexible flexible printed wiring board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a flexible printed wiring board that is expandable and contractible.

(Prior Art) Since the outer dimensions of the completed flexible printed wiring board are fixed, it is particularly thin and highly flexible, and the circuit pattern integration density formed on the substrate is high. high,
Furthermore, in the case of a flexible printed wiring board that requires high accuracy in the cumulative pitch dimension between the assembled circuit terminals, in order to meet these requirements, conventionally, the following method was used to determine in advance as much as possible. Manufactured flexible printed wiring boards that were close to the external dimensions.

The circuit pattern is formed by a highly accurate printing method.

Design dimensions are corrected in anticipation of dimensional changes such as shrinkage that occur during the manufacturing process.

 Use materials with the smallest possible dimensional change.

FIG. 3 is an explanatory view of an example of a conventional flexible printed wiring board, FIG. 3 (A) is a top view, FIG. 3 (B) is a sectional view taken along line XX of FIG. FIG. 3B is an enlarged detailed view of one circuit conductor group in FIG.

In the drawings, (1) is a base film, (2) is a copper foil, (3) is a coverlay film, (4) is a circuit conductor,
(5) is a circuit conductor group.

This flexible printed wiring board is a product that is strictly required to have a dimensional accuracy of 260.5 ± 0.1 mm as shown by (P) in the figure, and the circuit pattern is formed by a photo printing method. The product has a total length (L) of 270 mm and a width (W) of 25 mm
Then, as shown in (c) of the figure, a circuit conductor group (5) in which 50 conductors (4) having a circuit width of 0.2 mm are arranged in parallel at a pitch of 0.5 mm is defined as one block, interval
A total of 9 blocks (No. 1 to No. 9) are arranged in 5 mm. The base film (1) and the coverlay film (3) are 25 μm thick polyimide film, the copper foil (2) is 35 μm thick, and the circuit conductor (4) is 4 to 6 μm thick.
It is solder plating. Adhesives are present between the base film (1) and the copper foil (2) and between the copper foil (2) and the coverlay film (3), but they are omitted in the figure.

(Problems to be solved) Generally, in the process of manufacturing a flexible printed wiring board, heating such as heating and drying when laminating the base film and the copper foil, and heating such as pressure heating when laminating the coverlay film are performed. And cooling,
It is completed through various processing steps such as etching, processing due to chemical changes such as plating of conductor terminals, and machining such as drilling and shearing, which are subject to large external forces. Due to the restrictions imposed by the device on which the flexible printed wiring board is mounted, the finishing accuracy of each design dimension of the flexible printed wiring board is at the same level as the dimensional change between lots or within the lot that occurs with the above processing. There are some demands.

In such a case, the technique described above was used,
In the case of insufficient quality, it was empirically considered that the yield was taken into consideration by manufacturing a quantity larger than the necessary quantity in consideration of the yield and making the product inspection severe.

(Means for Solving the Problems) The present invention provides an expandable and flexible printed wiring board which solves the above-mentioned problems, and is characterized in that wiring is provided at a position that does not affect the circuit pattern at all. The slits formed by the sides parallel to the width direction of the plate and the sides having an angle to the sides are arranged in parallel with each other, and the intermittent slits are arranged so as to face each other in the width direction of the substrate. The reason for this is that it was provided transversely to give elasticity.

(Operation) As described above, in the flexible printed wiring board of the present invention, a slight external force is applied at the time of mounting by providing an intermittent slit that passes through the inside of the substrate and crosses the width direction of the substrate. As a result, it is possible to slightly expand and contract in the direction orthogonal to the direction of the intermittent slit, that is, in the longitudinal direction of the wiring board.
It can be adapted to the mounted counterpart component.

(Embodiment) FIG. 1 is a top view of an embodiment of a flexible printed wiring board according to the present invention, and FIG. 2 is an explanatory view of an example of an intermittent slit. In the drawings, the same symbols as those in FIG. 3 represent the same parts.

As shown in the drawing, at a position that does not have any influence on the circuit pattern of the wiring board, for example, in the space between the block (5) and the block (5) formed by the circuit conductor group,
Intermittent slits (6) are provided through the inside of the substrate and across the width of the substrate.

As shown in FIG. 2, the intermittent slit (6) is a slit having a side (61) parallel to the width direction of the wiring board and a side (62) having an angle (θ). At intervals of (W ₁ ) and (W ₂ ) in parallel with each other. In the example of FIG. 2, W ₁ = 2 mm, W ₂ = 1 m
Intermittent slits (6) were formed using a mold machined to have m, l ₁ = 4 mm, l ₂ = 2.5 mm, l ₃ = 1 mm and θ = 130 °.

Further, in this embodiment, the intermittent slit (6) as described above is firstly provided.
As shown in the figure, three zones are provided in the space between the third block and the fourth block and the space between the sixth block and the seventh block of the circuit conductor group (5) and are separated by these two intermittent slits. The conductor block is divided into three conductor blocks.

In order to improve the workability of aligning with the mating parts, a U-shaped cut (7) is made on the outer edge of the intermittent slit (6) as shown in FIG. 1 or the wiring board is extended. It is convenient to add a circular hole (8) of an appropriate size to the processed end of the slit as shown in FIG. 2 in order to increase the resistance to tearing.

The present embodiment described above is merely an example, and it is needless to say that the shape and size of the intermittent slits, the position and the number of the intermittent slits can be appropriately changed without departing from the spirit of the present invention.

(Effect of the device) As described above, according to the flexible printed wiring board of the present invention, it is possible to easily make a slight expansion / contraction (it is possible to expand / contract up to about 0.5 mm in the product of the embodiment) with a slight force. Therefore, when this is joined to the mating part, it is possible to make delicate dimension adjustment, and it is possible to relieve what was conventionally required to strictly adhere to strict dimensional tolerances.

As a result, product yield can be improved and inspection
If possible, reduce MH. In addition, the time required for alignment at the time of mounting is shortened and workability is improved.

[Brief description of drawings]

FIG. 1 is a top view of a stretchable flexible printed wiring board according to the present invention, and FIG. 2 is an explanatory view of an example of an intermittent slit. FIG. 3 is an explanatory view of a conventional flexible printed wiring board. FIG. 3 (A) is a top view, FIG. 3 (B) is a cross-sectional view taken along the line XX in (A), and FIG. (A) It is an enlarged detailed view of one circuit conductor group in the figure. 1 ... Base film, 2 ... Copper foil, 3 ... Coverlay film, 4 ... Circuit conductor, 5 ... Conductor block, 6 ... Intermittent slit, 7 ... Notch, 8 ... Slit end round hole.

Claims (1)

[Scope of utility model registration request] 1. A slit formed by a side parallel to a width direction of a wiring board and a side having an angle with the side at a position having no influence on a circuit pattern and arranged in parallel with each other with a space therebetween. A stretchable flexible printed wiring board, characterized in that the intermittent slits are provided so as to pass through the inside of the substrate and cross the width direction of the substrate to impart elasticity.