Electrical connectors – Electromagnetic or electrostatic shield – Shielding individually surrounding or interposed between...
Reexamination Certificate
2000-03-28
2001-10-23
Donovan, Lincoln (Department: 2832)
Electrical connectors
Electromagnetic or electrostatic shield
Shielding individually surrounding or interposed between...
C428S411100
Reexamination Certificate
active
06305985
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not Applicable
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
Not Applicable
REFERENCE TO A MICROFICHE APPENDIX
Not Applicable
BACKGROUND OF THE INVENTION
Description of Related Art
Recently, according to the trend toward electric automobiles or hybridization of automobiles and multiplexing of electric signals for controlling electric and electronic devices mounted in automobiles, an electromagnetic shield technique is strongly desired for various kinds of electric wires and connectors comprising a wire harness to serve as a cable way.
In the case of the connectors, the shield effect with respect to electromagnetic waves is required for both preventing radiation of the electromagnetic waves from a terminal accommodated in a connector housing to the outside and preventing influence on an electric signal in a terminal in a connector housing from the outside electromagnetic waves.
In order to meet such demands, various proposals have been provided.
For example, Japanese Patent Publication No. 10-144406A discloses a method for providing a shield effect with conductive material powders by introducing powders of a conductive material having the excellent absorbing property with respect to electromagnetic waves, such as ferrite into the outer wall of a resin connector housing or a resin cover for covering the periphery of the connector housing.
Moreover, Japanese Patent Publication No. 8-298168A discloses a method for providing a desired shield effect with an electromagnetic blocking plate by providing an electromagnetic blocking plate comprising a metal plate in a resin connector housing or on the outer surface thereof.
Furthermore, a method for providing a desired shield effect with a conductive thin film by providing a conductive thin film on the outer surface of a resin connector housing by applying electroless plating or a conductive coating is proposed.
However, the method of introducing conductive material powders into a resin connector housing or cover arises a problem in that there is a risk of partially producing a portion having a low shield effect unless the conductive material powders are dispersed homogeneously and with an appropriate concentration in the resin material and thus it is difficult to obtain a stable shield performance. Moreover, since a step of mixing and agitating the conductive material powders in the resin material is required, problems of the material cost rise and the connector cost rise due to complication of the connector forming process are involved.
Further, the method of providing a shield effect with the electromagnetic blocking plate comprising a metal plate arises a problem in that the weight of the connector is increased due to the weight of the metal plate. Moreover, a problem of drastic cost rise of the connector due to increase of the number of components of the connector is involved.
Further, the method of providing the shield effect with the conductive thin film formed by application of electroless plating or a conductive coating arises a problem in that the film thickness of the formed conductive thin film tends to be irregular in the case the connector housing has a complicated structure with many projections and recesses so that there is a risk of partially producing a portion having a low shield effect due to the film thickness irregularity, and thus it is difficult to obtain a stable shield performance. Moreover, since the forming process of the conductive thin film is required as a formation step of the connector and the material cost of the conductive thin film is needed, a problem of cost rise is involved.
SUMMARY OF THE INVENTION
In order to solve the problems, an object of the invention is to provide a connector provided with an electromagnetic shield capable of easily providing an electromagnetic shield layer on the surface of a connector housing with a homogeneous thickness even in the case the connector housing has a complicated structure with many projections and recesses so as to obtain the excellent electromagnetic shield effect as well as capable of reducing the connector cost without increase of the number of the connector components or increase of the weight, and a method of manufacturing the connector and an apparatus used for the method.
In order to achieve the above object, according to the present invention, there is provided a connector comprising:
a housing body made of graphitizable material having insulation property; and
a graphitized electromagnetic shield layer formed by irradiating a laser beam onto the surface of the housing body in inert gas atmosphere.
In the connector provided with an electromagnetic shield of the above-mentioned configuration, since the electromagnetic shield layer is produced by graphitization of the surface of the connector housing itself comprising a thermoplastic resin material by the laser beam irradiation, unlike the case of mounting a metal electromagnetic blocking plate as a separate member, there is no risk of increasing the number of components of the connector or increasing the weight.
Moreover, since the above-mentioned electromagnetic shield layer of the connector provided with an electromagnetic shield can be easily provided with a homogeneous thickness on the surface of the connector housing even in the case the connector housing has a complicated structure with many projections and recesses compared with the connector wherein the conductive thin film is formed by application of the electroless plating or the conductive coating on the outer surface of the connector housing or the connector wherein the conductive material powders are introduced into the resin material of the connector housing.
Accordingly, an electromagnetic shield layer with a homogeneous thickness can be provided easily on the surface of a connector housing even in the case the connector housing has a complicated structure with many projections and recesses so as to obtain the excellent electromagnetic shield effect. Furthermore, since the number of the connector components or the weight is not increased, the cost of the connector can be reduced.
Examples of the graphitizable material to be used in the invention include easily graphitizable polymer resin materials such as polypropylene, polyamide, polyvinyl compounds, and polyimide.
Recently, for example, as disclosed in I.E.E.J. Vol. 117-A, No. 6, pp. 638-644 (1997), experiments have been executed for forming a graphitized conductive path along the irradiation locus by irradiating the surface of a film comprising an easily graphitizable polymer resin material such as polyimide and vinyl chloride directly with a laser beam.
According to the article, by irradiating a polyimide captone film (such as a captone film produced by DuPont-Toray Co., Ltd.) with a 10 Hz pulse YAG laser (Spectra-Physics GCR-150: 7 mm beam diameter, 243 mJ energy per 1 pulse, 1,064 nm wavelength, 8 nsec pulse width) in a nitrogen atmosphere for 5 to 90 minutes, a graphitized layer of about 20 &mgr;m thickness was formed in 30 minutes irradiation time, and a graphitized layer of about 30 &mgr;m thickness was formed in 60 minutes irradiation time. The formed conductive path has a 0.6 to 1.3 &OHgr;cm resistivity and the graphitized material is effective for locking the electromagnetic waves.
Preferably, the connector further comprises an insulating material layer formed on the electromagnetic shield layer.
According to the configuration, damage of the electromagnetic shield layer by contact with other substances can be prevented so that the reliability of the shield performance by the electromagnetic shield layer can be improved as well as the durability can be improved.
According to the present invention, there is also provided a method of manufacturing a connector provided with an electromagnetic shield, comprising the steps of:
placing a connector housing made of graphitizable material having insulation property in a room filled with an inert gas; and
irradiating a laser beam onto the surface of the housing body to form a graphitized elect
Donovan Lincoln
Sughrue Mion Zinn Macpeak & Seas, PLLC
Yazaki -Corporation
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