Heavy-base semiconductor rectifier

Claim 1

A SEMICONDUCTOR DEVICE INCLUDING IN COMBINATION, A MEAL BASE MEMBER HAVING A BOTTOM WALL AND AN ANNULAR SIDE WALL FORMING A RECESS IN THE BASE OPENING AT THE TOP OF SAID ANNULAR SIDE WALL, A SEMICONDUCTOR UNIT CENTERED AT THE BOTTOM OF SAID RECESS AND SECURED TO SAID BOTTOM WALL, MEANS FOR CLOSING THE BASE OPENING AND SEALING THE DEVICE AT THE BASE OPENING, SAID MEANS INCLUDING A WELDING RING SECURED TO THE TOP OF SAID ANNULAR SIDE WALL AROUND SAID OPENING, AND A COVER OVER SAID BASE OPENING INCLUDING AN ANNULAR METAL RING HAVING CENTRAL OPENING THEREIN AND INSULATING MATERIAL IN SAID CENTRAL OPENING, SAID ANNULAR METAL RING HAVING AN INNER ANNULAR RIM PORTION EXTENDING DOWNWARDLY INTO THE BASE RECESS, AND SAID ANNULAR METAL RING FURTHER HAVING A WEB PORTION EXTENDING RADIALLY OUTWARD FROM SAID INNER ANNULAR RIM OVER AT LEAST A PART OF THE RADIAL WIDTH OF SAID WELDING RING, WITH ONE OF SAID TWO RINGS HAVING A CIRCULAR PROJECTING PORTION OUTSIDE SAID BASE OPENING EXTENDING TO THE OTHER SAID RING AND WELDED THERETO, SAID PROJECTING PORTION BEING NARROWER IN ITS DIMENSION BETWEEN SAID RINGS THAN THE CORRESPONDING DIMENSION OF SAID INNER ANNULAR RIM MEASURED FROM THE BOTTOM OF SAID WEB INTO SAID BASE RECESS, AND STIFF LEAD MEANS EXTENDING UPWARDLY FROM SAID SEMICONDUCTOR UNIT THROUGH SAID INSULATING MATERIAL OF SAID COVER AND SUPPORTED IN A CENTERED POSITION WITHIN SAID BASE OPENING BY SAID INSULATING MATERIAL.