Plastic encapsulated semiconductor devices

Abstract

Abstract A PLURALITY OF SEMICONDUCTOR DEVICES ARE ENCAPSULATED SIMULTANEOUSLY IN A THERMOSETTING PLASTIC BY A PROCESS THAT INCLUDES THE USE OF TRANSFER MOLDING TECHNIQUES. DISCRETE SEMICONDUCTOR DEVICES, SUCH AS TRANSISTORS, ARE STRIP MOLDED AS A UNIT AND SEPARATED AFTER THE THERMOSETTING PLASTIC HAS CURED. PRIOR TO THE MOLDING PROCESS, AN ARRAY OF LEAD WIRES INTERCONNECTED BY PARTIALLY SHEARED TIE-BARS ARE STAKED TO INDIVIDUAL HEAT SINKS ALSO FORMED IN A STRIP. A SEMICONDUCTOR DEVICE IS MOUNTED TO EACH OF THE INDIVIDUAL HEAT SINKS AND WHISKER LEAD WIRES ARE BONDED TO THE ACTIVE REGIONS OF THE DEVICE AND THE LEAD WIRES. TO PREVENT CONTAMINATION OF THE SEMICONDUCTOR JUNCTIONS WITH ATMOSPHERIC IMPURITIES, THE WAFERS ARE COATED WITH A PROTECTIVE MATERIAL. GROOVES ARE COINED INTO THE HEAT SINK TO LIMIT THE WAFER COATING MATERIAL TO A RESTRICTED AREA. AFTER THE STRIP MOLDING STEP HAS BEEN COMPLETED, THE INDIVIDUAL SEMICONDUCTOR DEVICES ARE SEPARATED BY CUTTING THE TIE-BARS AND SAWING THE INDIVIDUAL HEAT SINKS.

Inventors

• 👤 James H Overman

Bibliographic Details