Patent ID: 6838377

Claim:
A method of producing a high frequency circuit chip having a substrate made of a ceramic with a high dielectric constant, a wiring pattern provided on one main surface of the substrate, an electric conductor layer provided on substantially all of another main surface of the substrate, and a through-hole including a connecting electrode for connecting the wiring pattern and the conductor layer to each other, the method comprising the steps of: filling electrically conductive paste into a perforation in the substrate, and firing the paste to form the connecting electrode of the through-hole; forming a resist pattern with an opening having a desired shape and size directly on the substrate; forming a thin film with a wiring material directly on the substrate through the opening over the resist pattern after forming the resist pattern; removing the unnecessary wiring material thin film deposited on the resist pattern together with the resist pattern to form the wiring pattern directly on the substrate by a lift-off method; mirror-polishing at least the surface of the fired substrate on which the wiring pattern is formed, and the fired substrate in which the through-hole having the connecting electrode is formed; and thereafter forming the wiring pattern on the mirror-polished surface by the lift-off method; wherein the thin film includes an adhesion layer formed on the substrate, a major conductor layer formed on the adhesion layer, a buffer layer formed on the major conductor layer, and a wire bonding layer formed on the buffer layer.