ELECTRONIC CIRCUIT DEVICE HAVING MULTILAYER SUBSTRATE

摘要

PROBLEM TO BE SOLVED: To provide an electronic circuit device that can restrain the degradation of electrical characteristics for improving heat radiation. SOLUTION: A concave 24 is provided in a multilayer substrate 21. A ground conductor layer 30 is provided so that the bottom surface 25 of the concave 24 is included. An FET 2 is positioned in the concave 24. The source electrode of the FET 2 is connected to the ground conductor layer 30 in the concave 24 using a wire 29. A through-hole 39 is formed in the dielectric layer 36 under the FET 2 and filled with a conductor 41 having satisfactory heat radiating property. First and second dielectric layer 34, 35 are disposed on the ground conductor layer 30. A low-power FET 1, strip line conductor layers 9a, 10a, etc., and disposed on the first dielectric layer 34. A bias power conductor or the like is provided limitedly on the surface of the second dielectric layer 35.