Electrically insulating substrate
First Claim
1. A precursor for an electrically insulating substrate having a glazed porcelain surface for receiving electrical circuitry thereon;
- comparatively low thermal coefficient of expansion;
comparatively high thermal conductivity for heat dissipation;
good electrical insulation properties; and
sufficient mechanical strength for subsequent use in a microelectronic circuit having surface mounted devices disposed thereon;
which comprises;
a first plurality of porcelain green sheets having a relatively low linear thermal coefficient of expansion matched to the linear thermal coefficient of expansion of the surface mounted devices to be subsequently mounted upon the substrate; and
a second plurality of fine mesh wire cloth sheets for mechanical strength and high thermal conductivity;
said second plurality of fine mesh wire cloth sheets interleaved between the first plurality of porcelain green sheets to separate the fine mesh wire sheets by at least one porcelain green sheet to provide electrical insulation between the wire cloth sheets, wherein the interleaved porcelain green sheets and the fine mesh wire cloth sheets have been compressed against one another at a somewhat elevated temperature with sufficient pressure to form a laminated substrate, for subsequent firing at a further elevated temperature sufficient to form at least one outermost glazed porcelain surface.
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Accused Products
Abstract
An apparatus for fabricating composite porcelain substrates employing alternating layers of wire cloth and porcelain green sheet material is disclosed, wherein those alternating layers are compressed toward one another at a somewhat elevated temperature and then kiln fired at a further elevated temperature to form a glazed porcelain surface for receiving further electrical circuitry, for example, of the microelectronic type. Such a composite porcelain substrate has good thermal properties of high conductivity and low coefficient of expansion as well as good electrical insulating properties and mechanical strength. In particular its thermal expansion properties are well matched to many surface mounted devices that may be placed on the substrate thereby reducing the likelihood of thermal damage of device connections. The substrate cost is very low in comparison to the currently available alternatives.
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Citations
20 Claims
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1. A precursor for an electrically insulating substrate having a glazed porcelain surface for receiving electrical circuitry thereon;
- comparatively low thermal coefficient of expansion;
comparatively high thermal conductivity for heat dissipation;
good electrical insulation properties; and
sufficient mechanical strength for subsequent use in a microelectronic circuit having surface mounted devices disposed thereon;
which comprises;a first plurality of porcelain green sheets having a relatively low linear thermal coefficient of expansion matched to the linear thermal coefficient of expansion of the surface mounted devices to be subsequently mounted upon the substrate; and
a second plurality of fine mesh wire cloth sheets for mechanical strength and high thermal conductivity;said second plurality of fine mesh wire cloth sheets interleaved between the first plurality of porcelain green sheets to separate the fine mesh wire sheets by at least one porcelain green sheet to provide electrical insulation between the wire cloth sheets, wherein the interleaved porcelain green sheets and the fine mesh wire cloth sheets have been compressed against one another at a somewhat elevated temperature with sufficient pressure to form a laminated substrate, for subsequent firing at a further elevated temperature sufficient to form at least one outermost glazed porcelain surface. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
- comparatively low thermal coefficient of expansion;
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12. A fired composite insulating substrate for mounting electrical components thereon, which comprises:
a plurality of porcelain sheets and fine wire mesh sheets, interleaved to insulate the fine wire mesh sheets between the porcelain sheets, said interleaved sheets having been pressure laminated prior to firing, wherein thermal energy generated by circuitry and electrical components mounted on the substrate is dissipated through at least one insulative porcelain sheet to the fine wire mesh sheets interleaved within the substrate, said fine wire mesh sheets providing the substrate with mechanical strength and thermal expansion characteristics comparable to alumina. - View Dependent Claims (13, 14, 15, 16)
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17. An electrically insulating substrate having a glazed porcelain surface;
- comparatively low thermal coefficient of expansion;
comparatively high thermal conductivity;
good electrical insulation properties; and
high mechanical strength formed by firing a composite comprising;a first plurality of porcelain green sheets having a relatively low linear thermal coefficient of expansion; and
a second plurality of fine mesh wire cloth sheets interleaved between the first plurality of porcelain green sheets to separate the fine mesh wire sheets by at least one porcelain green sheet to provide electrical insulation between the wire cloth sheets, wherein the interleaved porcelain green sheets and the fine mesh wire cloth sheets are compressed against one another at a somewhat elevated temperature with sufficient pressure to form a laminated substrate. - View Dependent Claims (18, 19, 20)
- comparatively low thermal coefficient of expansion;
Specification