JPH073658Y2 - Injection molded printed circuit board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an injection-molded printed circuit board, and in particular, reduces and absorbs a difference in linear expansion coefficient between a conductive circuit portion and a substrate portion of injection-molded resin or a difference between bending strains. The present invention relates to an injection-molded printed circuit board configured as described above.

In general, for example, in a composite material composed of a combination of various materials, such as a metal and a thermoplastic material,
The properties of the resulting composite material greatly vary depending on the method of joining these materials and the adhesive used to bond them together.

Furthermore, in the case of a printed circuit board obtained by injection molding according to the present invention, the molding strain in the molding die, that is, the residual strain remaining after molding is large, and the molding substrate shrinks over time. Wrinkles are formed between the injection-molded substrate and the injection-molded substrate.

That is, such a conventional technique has the following problems.

1) Circuit breakage occurs due to distortion due to bending of the injection molded printed circuit board. Further, even if the wire is not broken, the elongation strain increases the circuit resistance.

2) For example, when a polyimide film is used as a base film in a so-called flexible printed circuit, the adhesiveness of polyimide is poor in the first place, and it becomes difficult to select it when it is combined with a molding material resin in injection molding. The polyimide of the circuit film is wrinkled due to the shrinkage of the resin.

3) As with the problem of 2) above, wrinkles appear due to the difference in the coefficient of linear expansion between materials during thermal cycling.

The present invention solves the above problems in the related art, and the difference between the linear expansion coefficients of the conductive circuit portion and the substrate portion of the injection-molded resin,
Another object is to provide an injection molded printed circuit board configured to reduce and absorb the difference between bending strains.

The injection-molded printed circuit board 1 according to the present invention has a circuit film 2 in which a copper foil or a conductive paste is adhered to a plastic film and a desired conductive circuit is formed, and the circuit film 2 is integrally formed by insert formation as shown in the drawings. In the injection-molded printed circuit board 1 obtained by converting
Alternatively, the conductive circuit film material 2 in the portion 4 where only the wiring of the conductive circuit pattern is not mounted without mounting a component (not shown)
And the resin portion 5 serving as the base of the injection-molded substrate are floated from each other and separated from each other.

That is, as shown in FIGS. 1a to 4, the conductive circuit film material 2 in the bent portion 3 or in the portion 4 where only the wiring of the circuit pattern without mounting parts such as electric elements is mounted.
And the substrate resin portion 5 formed by injection molding are floated and separated to provide a concave portion, that is, a bending space 6. Alternatively, a portion 8 which is not integrated with the substrate molding resin is provided by not attaching the adhesive layer 7. This absorbs and alleviates wrinkles and strains due to the flexibility and shrinkage of the resin over time, or the difference in linear expansion coefficient with respect to temperature changes.

In particular, regarding bending, it is possible to allow bending strain to escape to the recess 6 by providing the recess 6 as shown in FIGS. 1a to 4 with the slide core 14 or the like.

In FIGS. 2a, 2b, and 2c, for example, assuming that the component mounting parts of the injection-molded printed circuit board 1 are A to E,
The conductive circuit film material 2 is not integrated with the board resin portion 5 over the front surface but is floated by removing the broken line frame substantially required for component mounting of A to E. It is possible to reduce the strain due to the difference in expansion coefficient.

Even if it is a component-mounted type, the design shown in Fig. 2a is possible during the artwork process.

In this case, a schematic sectional view taken along the line F-G of FIG. 2a is shown in FIG. 2b, and a bending space, that is, a recess 6 is provided to configure a portion 4 of only the wiring of the conductive circuit pattern in which no component is mounted. is doing.

FIG. 2c shows a cross section of still another embodiment, showing a portion 8 where the circuit film material 2 is not integrated with the substrate molding resin portion 5 without providing the adhesive layer 7. That is, this 8
The circuit film material 2 in the portion of is the resin portion 5 of the base.
It is floating from.

Next, a box of another embodiment as shown in FIGS. 3a and 3b is shown, and a circuit is formed on the inner surface of the box by in-mold molding by a transfer method.

Of course, not only in-molding but also post-transferring can be performed in the same manner.

The circuit is molded on the transfer foil 9, and the mold is made by injection molding.
Set inside.

As shown in FIG. 4, the transfer foil 9 is sent out by the sending roll 12 and the winding roll 13 above and below the injection mold, that is, between the cavity mold 10 and the core mold 11. Next, the circuit to be transferred is positioned within the molds 10 and 11.

The slide core 14 deals with and forms the portion 8 in which the circuit is floated by making it concave for bending.

In the figure, the molten resin of the resin portion 5 serving as the base is injected from the resin injection port 15 on the side of the cavity 10, and is molded integrally with the circuit film material 2 that is sent, that is, the transfer foil 9 of the circuit.

The effects of the present invention are as follows.

(A) An injection-molded printed circuit board with improved flexibility is obtained. It is possible to reduce the compression or bending strain applied to the circuit film material 2 regardless of whether the circuit portion is bent inward or outward.

(B) The shrinkage of the resin portion 5 after molding can be absorbed.

[Brief description of drawings]

FIG. 1a is a cross-sectional view showing an essential part of an embodiment product of the present invention, and FIGS. 1b and 1c are cross-sectional views showing bent portions of the embodiment product of the present invention, respectively. 2a is a schematic plan view showing another embodiment of the present invention, FIG. 2b is a schematic cross-sectional view taken along the line F-G of FIG. 2a, and FIG. 2c is a further embodiment. FIG. 3a is a schematic sectional view showing a box of yet another embodiment of the present invention, and FIG. 3b is a schematic sectional view showing the same assembled into a box. Furthermore, FIG. 4 is an explanatory schematic diagram showing a manufacturing apparatus according to still another embodiment of the present invention. 1 …… Injection molded printed circuit board 2 …… Circuit film, that is, conductive circuit film material 3 …… Bent portion 4 …… A part where only the wiring of the conductive circuit pattern without components is mounted 5 …… Resin that is the base of the injection molded substrate Part 6 ... Bending space (recess), 7 ... Adhesive layer 8 ... Part where circuit film material 2 is not integrated with substrate molding resin part 9 ... Circuit transfer foil 10 ... Injection molding upper mold (cavity) Tee type) 11 …… Injection molding lower die (core type) 12 …… Sending roll, 13 …… Winding roll 14 …… Slide core, 15 …… Molded resin injection port A, B, C, D, E …… Space for mounting A to E parts

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Creator Hisao Nakajima 5-1-9 Higashi-Hachiman, Hiratsuka-shi, Kanagawa Furukawa Electric Co., Ltd. Hiratsuka Cable Works (56) References Japanese Patent Publication No. 47-25942 (JP, B1)

Claims (1)

[Scope of utility model registration request] 1. An injection-molded printed circuit board obtained by integrating a plastic film with a copper foil or a conductive paste to form a desired conductive circuit by insert molding without bending parts or parts. An injection-molded printed circuit board, characterized in that a conductive circuit film material in a portion only of wiring of a conductive circuit pattern and a resin portion serving as a base of the injection-molded substrate are floated and separated from each other.