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An electrical heating device comprising a substrate having an upper insulating surface, a semi-conductor pattern carried on the insulating surface, and a pair of metallic conductors mounted in face-to-face engagement with said semi-conductor pattern. The semi-conductor pattern includes a pair of spa

An electrical heating device comprising a substrate having an upper insulating surface, a semi-conductor pattern carried on the insulating surface, and a pair of metallic conductors mounted in face-to-face engagement with said semi-conductor pattern. The semi-conductor pattern includes a pair of spaced connector portions and at least one heating portion extending between and electrically connected to each of said connector portions, the connector portions have a electrical conductivity greater than that of said heating portion, and each of the metallic conductors is in face-to-face engagement with a respective one of said connector portions and has an area that is less than that of said respective one of said connector portions and an area:perimeter ratio greater than D/20 wherein D is the major dimension of the respective conductor portion.

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In an electrical heating device comprising a generally flat substrate having an upper insulating surface, a semi-conductor pattern carried by said upper surface of said substrate, and a pair of generally flat metallic conductors mounted in a face-to-face engagement with said semi-conductor pattern,

In an electrical heating device comprising a generally flat substrate having an upper insulating surface, a semi-conductor pattern carried by said upper surface of said substrate, and a pair of generally flat metallic conductors mounted in a face-to-face engagement with said semi-conductor pattern, that improvement wherein: said semi-conductor pattern includes a pair of spaced connector portions and at least one heating portion extending between and electrically connected to each of said connector portions; said connector portions have an electrical conductivity greater than that of said said heating portion; and, each of said metallic conductors is in face-to-face engagement with a respective one of said connector portions, and the surface thereof in such engagement has an area that is less than the area of the upper surface of said respective one of said connector portions, the area:perimeter ratio of said surface of said conductor being about D/4 wherein D is the major dimension of said area of said conductor.