Thick film resistors for AlN ceramics

RuO₂ thick-film resistors for aluminum nitride (AlN) ceramics with controlled temperature coefficient of the resistor (TCR) and reliabilities have been developed. The resistors, in the range of approximately 10 Ω/□ to 10 kΩ/□ were obtained using a crystallized glass powder and a RuO₂ powder, binder materials, and a conducting material. The glass had a low PbO content of 6 wt %, a low thermal expansion coefficient of 3.6×10^-6/°C, and a softening point of 610°C. The resistors, to which MnO₂ was added to the above combination, had excellent TCRs of ±250 p.p.m./°C at 30 Ω/□ to 30 kΩ/□. These resistors showed small resistance changes, which were less than +1.0% after a thermal cycle test (-55-150°C, 1000 times) and high-temperature storage test, ( 150°C, 1000 h). They had excellent resistance stability. Further, the effect of particle size of glass and RuO₂ powders on electrical properties of the resistors containing the crystallized glass was similar to that in resistors containing noncrystallized glass for alumina ceramics