Coating processes – Solid particles or fibers applied – Applying superposed diverse coatings or coating a coated base
Patent
1996-10-17
1999-05-18
Morris, Terrel
Coating processes
Solid particles or fibers applied
Applying superposed diverse coatings or coating a coated base
427200, 4273899, 427394, 428 90, 428 96, B05D1/14
Patent
active
059049545
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a composite article and to a process for its manufacture.
It relates more particularly to a composite article including an electrically and/or thermally insulating substrate and protective layers for this substrate which are placed on each face thereof.
In the field of electrical technology electrical motors are generally insulated using flexible materials such as films made of plastic, like polyester films. However, these films can be sensitive to the environment, especially to moisture, or can have insufficient mechanical and heat-resistance properties. To overcome these disadvantages it has been proposed to form a composite material including an electrically insulating film sandwiched between two protective layers made of heat-resistant paper. This composite material requires, on the one hand, the manufacture of papers consisting, for example, of chopped aramid fibres and of fibrids, also of aramid, and, on the other hand, an application of the paper onto the electrically insulating support in a continuous manner in order to have good adhesiveness between the layers. This process for the manufacture of the composite material is relatively complex. In addition, the leaktightness of the protective paper layers, especially in relation to moisture, is not perfect.
Furthermore, electrically insulating substrates, especially electrically insulating flexible films, are also employed for the manufacture of flexible electrical printed circuits. These articles are obtained by metallizing one face, preferably both faces, of the film and then by producing electrical circuits by, for example, processes of chemical etching of the metallized layer. Electronic components such as transistors, diodes or capacitors are soldered onto these circuits, for example by tinning.
The support films must have good dimensional stability, especially at the soldering temperature. For this reason polyester films are increasingly replaced by films made of plastic which have improved heat resistance and dimensional stability, such as polyimide or polyaramid resins. However, the cost of manufacture of these plastics is much higher.
One of the objectives of the present invention is to overcome these disadvantages by proposing a thermally and electrically insulating composite material including protective layers which are leakproof, especially to moisture, and which can be obtained by a simple application process. This material can be employed as an electrically insulating substrate for the production of flexible electrical printed circuits after deposition of a metal layer on at least one of the faces of the composite material by the processes for application of a film of copper or for metallizing.
To this end the invention proposes a composite article including a continuous support layer and protective layers placed on at least one face of the support or substrate layer.
According to the invention at least one of the protective layers is formed by a heat-resistant resin including reinforcing fibres made of heat-resistant material which are flocked onto the surface of the support or substrate.
According to a preferred embodiment of the invention the support or substrate layer is an electrically and/or thermally insulating continuous layer.
Films made of electrically and/or thermally insulating synthetic material such as polyester, polyolefins, polycarbonates, polyphenylene sulphide, polyimides, thermotropic polyesters and the like, may be mentioned, by way of example, as support or substrate layer which is suitable for the invention.
Fibres made of heat-resistant material which are suitable for the invention are, for example, fibres made of polyimide, polyaramid and polyamide-imide.
Polyimide, polyamide-imide, polyaramid, bismaleimide, epoxy and triazine resins or a mixture thereof may be mentioned by way of example of heat-resistant resin which is suitable for the invention.
More advantageously, resins which are suitable for the invention are resins which can be deposited onto the layer of flocked fibres i
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Cassat Robert
Faure Jean-Paul
Kermel SNC.,
Morris Terrel
Solomon Andrew M.
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