Corpus Christi, Tex. TT Electronics IRC Advanced Film Division has developed a series of pulse withstanding thickfilm chip resistors with improved power ratings in smaller case sizes. Designated the PWC series, the surface-mount chip resistors deliver up to 50 percent higher power ratings than conventional thickfilm resistors in a standard 2512 package.
The new circuit protection resistors can be used as replacements for larger molded wirewound components or multi-chip circuit protection solutions that take up more board space and may require additional placement costs. "As electronic design engineers have increased the power density of their equipment, the demand for smaller surface mount single-chip circuit protection resistors has also increased," said Gary Bleasdell, new business development manager for TT electronics IRC Advanced Film Division.
The PWC series resistors are available in four standard sizes (0805, 1206, 2010 and 2512) with power ratings from 0.125 W to 1.5 W, and limiting element voltage ratings of 100 V to 500 V. Resistance values range from 1 ohm to 10 Megohm, with a tolerance down to 0.5 percent. Temperature coefficient of resistance (TCR) values are 100 ppm/°C for values over 10 ohm. The operating temperature range is -55°C to 155°C.
The PWC resistors provide up to 5 W in a 2512 chip size compared with conventional thickfilm resistors that typically provide up to 1 W in the same size package, Bleasdell said. IRC was able to boost the power rating up to 50% through a combination of proprietary thickfilm materials and advanced manufacturing processes, he said.
The pulse withstanding capability of the PWC resistors ranges up to 5 kV for a 2512 size with 1.2/50 microsecond and 10/700 microsecond pulse shapes as defined by IEC 60-115-1. The resistors have a thickfilm resistor element with an overglaze and organic protection screen-printed on alumina substrate. Wrap-around terminations feature an electroplated nickel barrier and tin-lead solder coating, which ensure leach resistance properties and high temperature (260°C) solderability. Applications include telecommunications, switch gears, power supplies and circuit protection devices.
The chip resistors are priced at $0.29 in quantities of 10,000. Delivery is eight to ten weeks.
TT Electronics IRC Advanced Film Division, 1-361-992-7900, www.irctt.com