of epoxy resin once the gel 9 has cooled the backing layer 10 is peeled off so as to leave the gel layer 9 exposed since the gel layer is spread over the entire work area the mold 6 and the devices 11 it is selectively removed from the parts that cover the mold 6 to remove layer 9 from the parts that cover mold 6 a mask 12 fig7 is applied that is provided with openings that allow the passage of ultraviolet rays only on the regions of the resin 9 that cover the power devices 11 these regions are accordingly exposed to uv rays 13 fig7 so as to cure or polymerize them as a result these regions cannot be removed with chemical treatments to remove the resin 9 placed on the mold 6 a chemical treatment with a saline solution of sodium carbonate na 2 co 3 is performed etching the regions that have not been exposed and cured by the uv rays 13 in this manner the structure shown in fig8 is obtained wherein the insulating layer 9 is left only on the devices 11 the insulating layer 9 epoxy resin is still not mechanically strong i e it can still be scratched and damaged mechanically to improve the mechanical strength of the insulating layer 9 a further curing or polymerization with uv rays 13 is performed finally heat curing in an oven is performed for about 8 hours at approximately 170 u00b0 c further polymerizing both the insulating layer 9 and the package 2 of the power device 11 to achieve better results the upper part 8 of the package 2 should protrude only by an amount that.