PURPOSE: To reduce the discontinuity of the earth surface by forming recessed parts on a part of metal carriers to which integrated circuits are connected so as to leave a part of the metal carriers from the end surfaces of the metal carriers to the lower part of an I/O transmission line as a pent-roof-like contact part with a base plate and by fitting a conductive member to the recessed parts so as to allow the member to contact with the upper surface of the recessed parts.

CONSTITUTION: The recessed parts 13, 13' are formed on the metal carriers 1, 1' to which the microwave integrated circuits 2, 2' are connected so that the pent-roof-like contacts parts with earth conductors 6, 6' are left on the upper part of the metal carriers 1, 1'. The conductive block member 12 consisting of conductive rubber for instance is mounted so as to fit to the recessed parts 13, 13' of the integrated circuits 2, 2' and a conductive ribbon 4 is connected to the integrated circuits 2, 2'. Said constitute causes the earth conductors 6, 6' to connect with each other at the same plane of the pent- roof-like contact parts 14, 14', so that the same plane of the pent-roof-like contact parts 14, 14', so that the discontinuity of the thickness direction of the metal carriers 1, 1' is removed, the mismatching of the connection part is reduced and the transmission characteristics are improved.