Plastic-molded LTS DC-SQUIDs for multichannel biomagnetic measurement systems

A plastic molding technique for SQUIDs has been developed to protect the chip from moisture damage. A 1.5-mm-thick layer of molding compound (epoxy resin, elastic resin, and silica powder) was poured over Ketchen-type DC-SQUID that has Nb/AlO/sub x//Nb Josephson junctions. The moisture resistance of these plastic-molded SQUIDs was examined by subjecting them to temperature and humidity storage tests (60/spl deg/C, 90% relative humidity, 1,000 hours), and then measuring their performance characteristics. The results showed that the plastic packaging protected the chip from moisture damage, while not affecting the noise performance of the SQUIDs. The plastic molding therefore improved reliability and ease in handling of such SQUIDs.