Nitrogen-Fireable Resistors: Emerging Technology for Thick-Film Hybrids

A nitrogen-fireable base-metal thick-film resistor system compatible with copper conductors has been developed. A lanthanum hexaboride conductive phase is used to make resistor compositions in the range 10 Ω/□−10 kΩ/□, and doped tin oxide is uses as the conductive in the 10 kΩ/□−1 MΩ/□ resistance range. An extensive technology transfer program to move this technology from the research laboratory to full commercial availability is under way. The environmental stability of 44 lots made in pilot, prototype, and manufacturing scale runs have been evaluated and confirm lot-to-lot reproducibility. Lanthanum boride members show good environmental stability under all conditions. Doped tin oxide members are humidity sensitive and require encapsulation. When encapsulated with an organic material, all grades show maximum changes of less than one percent after 1000 h of exposure to 85°C/85-percent relative humidity.