Patent ID: 8003438

Claim:
A method of fabricating a circuit module, comprising the steps of: (a) mounting at least one electronic component in a cavity provided in a ceramic multilayer substrate; (b) filling a space between the electronic component and the cavity with a thermosetting resin to planarize a surface of the filled cavity; (c) providing at least one opening in an insulating adhesive layer of a sheet having the insulating adhesive layer and a metal layer stacked on each other or in both of the insulating adhesive layer and the metal layer, and filling the opening with a conductive resin connected to the metal layer; (d) bonding the sheet and the ceramic multilayer substrate by the insulating adhesive layer and at the same time electrically connecting a wiring layer formed on the ceramic multilayer substrate with the conductive resin; and (e) patterning the metal layer of the sheet to form a wiring layer, wherein the step (b) of filling the space to planarize the surface of the filled cavity is carried out by first filling the cavity with the thermosetting resin by using an amount exceeding the difference between a volume of the cavity and that of the electronic component, thermally curing the filled thermosetting resin, and then polishing a surface of the cured thermosetting resin and wherein the height difference between a surface of the polished resin and that of the ceramic multilayer substrate around the cavity is less than a thickness of the insulating adhesive layer directly abutting the ceramic multilayer substrate.