JPS6313400A - Injection-molded unit with transcripted circuit - 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 [Technical Field] The present invention relates to a shield structure for an injection molded body with a transfer circuit.

[Prior art and its problems]

Recently, electromagnetic waves generated from information processing devices have become a problem. A countermeasure against this is to make the device housing a shield structure to reduce leakage of electromagnetic waves. However, most of the housings of recent equipment are injection molded plastics, and do not have a shielding effect by themselves. For this reason, methods such as using conductive plastic as a material for injection molding or applying conductive paint to the surface of the injection molded product have been adopted as shielding measures. Among these, the former method has problems in terms of cost, moldability, appearance, etc., and the latter method using conductive paint is the simplest method.

By the way, this method of using conductive paint is simple because if you want to make a housing by injection molding and install a circuit board with components mounted inside the housing, you only need to apply conductive paint to the housing. can obtain a shield effect. However, recently, a method has been developed in which a circuit pattern transfer sheet is set in an injection mold and the circuit pattern is transferred onto the inner surface of the housing at the same time as the injection molding process (Japanese Patent Application Laid-Open No. 1983-1993).
In the case of an injection molded article with a transfer circuit made by this method, it is not possible to apply conductive paint to the transfer circuit part. It became clear that there was a problem in that the shield could not be created.

c. Means for Solving the Problems and Their Effects] In view of the problems of the prior art as described above, the present invention provides an injection molded article with a transfer circuit in which electromagnetic shielding can be performed using a conductive paint.

In order to achieve this object, the present invention provides an injection molded article with a transfer circuit in which a transfer circuit is integrally provided on a required surface of the injection molded article, in which a conductive shield layer is integrally provided on the back surface and around the transfer circuit. A conductive paint is applied to at least the surface of the injection molded body on the transfer circuit side so as to cover the peripheral edge of the shield layer without covering the transfer circuit.

In this way, the shield layer provided on the back side of the transfer circuit is electrically connected to the conductive paint applied to the injection molded body, so that the transfer circuit can be shielded.

〔Example〕

FIG. 1 shows an injection molded article with a transfer circuit according to an embodiment of the present invention, in which 1 is a transfer circuit, which is composed of a conductor layer 2, a solder resist layer 3, and an insulating layer 4. A conductive shield layer 5 and an adhesive layer 6 are successively integrally formed on the back surface and around the transfer circuit 1. Reference numeral 7 denotes a housing formed by injection molding, which is integrated with the shield layer 5 and the transfer circuit 1 through an adhesive layer 6. Further, 8 is a conductive paint for shielding applied to the inner surface of the casing 7.

This conductive paint 8 is applied to cover the peripheral edge of the shield layer 5, except for the transfer circuit 1. As a result, the shield layer 5 and the conductive paint 8 are electrically connected, and the transfer circuit 1
is shielded from the outside.

Conventional transfer circuits do not have a shield layer 5, and the insulating layer 4 is an adhesive layer that is used to adhere to the housing 7, making it impossible to shield with conductive paint. That's why.

The injection molded article with a transfer circuit as described above can be manufactured as follows.

First, a transfer sheet is manufactured as shown in FIGS. 2 to 6. First, as shown in FIG. 2, a solder resist layer 3 is printed on a releasable base film 9 by screen printing. Next, as shown in FIG. 3, six conductor layers 2 are printed using conductive paste. As a conductive paste, low temperature curing resin is used.
A filler mixed with silver powder or copper powder is used as a filler to impart conductivity, and then an insulating layer 4 is printed on it (Fig. 4), and a shield layer 5 made of a conductive paste or the like is placed on top of it. Print (Figure 5). What is important here is that the shield N5 is printed not only on the top surface of the insulating layer 4 (corresponding to the back surface of the transfer circuit 1) but also around the insulating layer 4, that is, the periphery of the shield layer 5 is The purpose is to make contact with the base film 9. Thereafter, as shown in FIG. 6, an adhesive layer 6 is printed to complete a transfer sheet.

The insulating layer 4 is for insulating the shield layer 5 and the conductor layer 2. Moreover, the adhesive layer 6 is for adhering the shield layer 5 to the plastic injection molded on the outside thereof. Therefore, the adhesive layer 6 may be omitted if the shield layer 5 has adhesive properties with the plastic to be injection molded.

The transfer sheet manufactured as described above is set in a mold for injection molding, and injection molding is performed to form the housing 7 as shown in FIG. 7. As a result, the transfer circuit 1 is integrated with the housing 7 via the shield layer 5 and the adhesive layer 6. Next, when the base film 9 is peeled off, the peripheral edges of the transfer circuit 1 and the shield layer 5 are exposed on the inner surface of the housing 7, so as shown in FIG. A conductive paint 8 is applied to the entire inner surface (or inner and outer surfaces) of the housing 7. After the paint has dried,
If the cover 10 is peeled off, a molded body with a transfer circuit as shown in FIG. 1 will be obtained.

In the above embodiments, the case where the injection molded object is a casing has been described, but the injection molded object may be something other than a casing, for example, a simple plate-like object.

〔Effect of the invention〕

As explained above, according to the present invention, since the injection molded article with a transfer circuit can be shielded with a conductive paint, there is an advantage that a molded article with a transfer circuit having a shield structure can be obtained at a low cost.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an injection molded article with a transfer circuit according to an embodiment of the present invention, and FIGS. 2 to 8 are sectional views showing the manufacturing method thereof in order of steps. 1-transfer circuit, 2-conductor layer, 3-solder resist layer, 4-
Insulating insulation, 5-shield layer, 6-adhesive layer, 7-casing (injection molded product), 8-conductive paint. Figure 6

Claims (1)

[Claims] In an injection molded article with a transfer circuit, in which a transfer circuit is integrally provided on a required surface of the injection molded article, a conductive shield layer is integrally provided on the back surface and around the transfer circuit, and at least on the side of the transfer circuit of the injection molded article. on the surface of the shield layer so as to cover the periphery of the shield layer without covering the transfer circuit.
An injection molded article with a transfer circuit coated with conductive paint.