A METALLIZED PULSE CAPACITOR FOR THE COPPER LASER INVERTER

ADDRESSING THE NEED FOR HIGHER RELIABILITY PULSE CAPACITORS TO SERVE DEMANDING APPLICATONS SUCHAS THE COPPER LASER INVERTER, A METALLIZED CAPACITOR IS PLANNED WITH A RATING OF 1-2 MICROFARADS (UF)/2000V, THAT HAS SUPERIOR DV-DT AND HIGH FREQUENCY CURRENT CARRYING CHARACTERISTICS, AND PROLONGED LIFE AT HIGH VOLTAGES AND HIGH LEVELS OF CORONA DISCHARGE. SEVERAL INNOVATIVE IMPROVEMENTS HAVE BEEN INCORPORATED IN THE DESIGN THAT ARE NOT FOUND IN COMMERCIALLY AVAILABLE PARTS. A NEW IMPROVED POLYPROPYLENE FILM WILL BE USED THAT IS PRODUCED BY A PATENED PROCESS AND HAS UNIQUE ELECTRICAL, THERMAL, AND MECHANICAL PROPERTIES. THIS IS A HYBRID FILM, COMPOSED OF CAPACITOR GRADE POLYPROPYLENE FILM AND AN ACRYLATE POLYMER COATING THAT HAS EXCELLENT DIELECTRIC AND SELFHEALING PROPERTIES, AND IS THERMALLY STABLE AT TEMPERATURES IN EXCESS OF 300 DEGREES CENTIGRADE. THE QUALITY OF THE TERMINATION IS ENHANCED AND THE EQIVALENT SERIES RESISTANCE (ESR) IS LOWERED, WITH THE USE OF A HEAVY EDGE ELECTRODE THAT HAS A RESISTIVITY OF LESS THAN 1.0 OHM/SQ CMM AND AN IMPROVED SPRAY TERMINATION. THE EQUIVALENT SERIES INDUCTANCE (ESL) OF THE CAPCAITOR BANK WILL BE LOWERED AND THE VOLUMETRIC EFFICIENCY INCREASED BY ASSEMBLING SEVERAL WOUND ROLLS INTO ONE CASE AND THEN BY RPLACING THE WIRE LEADS WITH A LOW INDUCTANCE MULTI-PIN LEAD FRAME. THE PHASE I DEVELOPMENT WORK WILL INVOLVE PRODUCTION AND METALLIZATION OF THE HYBRID FILM, CONSTRUCTION OF WOUND METALLIZED CAPACITORS, AND PERFORMANCE EVALUATION OF SINGLE CAPACITOR SECTIONS UNDER HIGH CURRENT AND VOLTAGE TESTS. IN PHASE II THE MATERIALS AND PROCESSES WILL BE OPTIMIZED AND LOW ESR AND ESL MULTISECTION CAPACITORS WILL BE PRODUCED AND PACKAGED IN A SINGLE PLASTIC CASE. SEVERAL 50 UF CAPACITOR BANKS WILL BE BUILT ON PRINTED CIRCUIT BOARDS AND WILL BE TESTED, BASED ON THE COPPERLASER INVERTER SPECIFICATIONS AND ON ADDITIONAL ACCELERATED LIFE TESTS, TO ESTABLISH LONGER TERM PERFORMANCE CHARACTERISTICS.