JPH046219Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention provides an electrolytic body foil and a rolled body foil on a flexible insulating film made of polyimide, polyester, etc., leaves this in a pattern of a desired shape, and uses this pattern to form one piece. The present invention relates to a flexible printed circuit board that connects an electric circuit to another electric circuit.

Traditionally, in this type of printed circuit board, it has been possible to use a wide pattern, such as providing a wide pattern on one side to shield the pattern on the other side, or widening the pattern width to increase current capacity. be.

For example, as shown in FIG. 1, one side of the base film 1 has several patterns 2 for connecting one electric circuit to another, and the other side has several patterns 2 for shielding the core pattern 2. A wide pattern 3 is provided.

When this flexible printed circuit board is bent in its longitudinal direction as shown in FIG. 2, as the bending R becomes smaller, the difference between the length of the pattern 3 on the inner surface and the pattern 2 on the outer surface becomes smaller. It's getting to the point where I can't ignore it.

Therefore, patterns 2 and 3 will be subject to expansion and contraction due to the difference between them, but if the width of the pattern in the longitudinal direction is small, the copper foil forming the pattern will expand and contract somewhat to compensate for the difference. However, when the pattern 3 is wide like the one mentioned above, the stress for expansion and contraction increases, making it difficult to expand and contract, and the pattern may peel off from the base film 1, or the pattern will crack and eventually break. Sometimes.

Moreover, this expansion/contraction stress reduces the flexibility of the base film 1, making it impossible to reduce the bending radius, resulting in disadvantages such as hindering the free movement of equipment and reducing reliability as described above. Ta.

The present invention provides such a wide pattern with a blank space that divides the pattern in the longitudinal direction, such as a mesh pattern, and makes the patterns that are connected in the longitudinal direction thinner, giving it elasticity. The purpose is to eliminate the above-mentioned drawbacks of the prior art.

An embodiment of the present invention will be described below with reference to FIGS. 3 and 4.

This embodiment is based on the base film 1 of the conventional example.
It is used when shielding the pattern 2 on one side of a diamond-shaped blank part 4 in the longitudinal direction and at a different position from that of the next row to form a mesh pattern 5. The width of the copper foil in the mesh portion is smaller than the radius of curvature R of the curved portion of the base film 1.

In this way, since the mesh pattern 5 is divided by the blank parts 4, the length of the close contact part in the bending direction is shortened as shown in FIG.
Therefore, arrow a where the copper foil inside the curved surface is contracted
The force in this direction will be weaker than that of conventional flexible substrates that are bonded long in the longitudinal direction.

Further, contrary to FIG. 4, even if the mesh pattern 5 is the outer surface of the bend R, the stretching force will be weaker than in the conventional case for the same reason.

In FIG. 5, the pattern for the shield is replaced with the mesh pattern shown in FIG. 3, and a circular blank part 9 is provided within the wide pattern 8, and in each case, the length in the longitudinal direction of the copper foil is The same effect as in the previous embodiment is obtained.

Each of the above embodiments is for a double-sided flexible printed circuit board in which a pattern is provided on both sides of the base film 1, but each of the above embodiments may also be applied to a single-sided flexible printed circuit board or a multilayer flexible printed circuit board with three or more layers. The same effect as
It is something that produces an effect.

As described above, the present invention has a pattern of metal foil, such as a wide copper foil, provided on an insulating film, with blank areas longitudinally and at different positions from those of the next row. Since the width of the mesh-like metal foil portion is smaller than the radius of curvature of the curved portion of the insulating film, the pattern is divided by the blank portion and the contact portion in the bending direction is made into a mesh shape. As the length becomes shorter, the copper foil on the inside of the curved surface is compressed, and the force in the direction is weaker than that of the copper foil that is bonded longer in the longitudinal direction.Conversely, even if the pattern is on the outside of the bending direction, the force that is stretched is This prevents the copper foil from peeling off or being cut from the insulating film, resulting in disconnection, increasing the bending resistance, improving the reliability of equipment, and also reducing the flexibility of the insulating film. It has the effect of ensuring that

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway plan view of a conventional flexible printed circuit board, Fig. 2 shows its bent state, Fig. 3 is a plan view of an embodiment of the present invention, and Fig. 4 is a cross section of the bent state. FIG. 5 is a plan view of another embodiment. 1...Base film, 2...Pattern, 4,
7, 9...blank area, 5...mesh pattern,
8...Wide pattern.

Claims (1)

[Scope of utility model registration request] In a wide metal foil pattern provided on a flexible insulating film, a pattern of metal foil is formed in a mesh shape with blank areas in the longitudinal direction and at different positions from those in the next row. A flexible printed circuit board, characterized in that the width of the mesh-like metal foil portion is smaller than the radius of curvature of the curved portion of the insulating film.