US Patent 7225536 Precasting multi-layer PCB process

A pre-casting multi-layer PCB process has steel plate mold engraved with circuitry and the epoxy coated on the mold for the epoxy to cover up a fiber glass substrate; conductive material coated on the epoxy to insert molding the former into the latter to form recessed circuitry; then baked and solidified, sandblasted to remove film for the conductive material to become conducted circuitry; the lamination made by layer for achieving even thinner PBC circuitry while maintaining sufficient structural strength.