Pastes for high temperature resistors in power hybrids and microwave circuits

AlN substrates with high stable thick film resistors are a suitable material combination for attenuators and terminations in microwave circuits for high frequency applications. The degradation of the FK 9200 resistors was investigated. Two competing interactions in the unencapsulated resistors were observed what correlates with a special influence of the atmosphere. By using of a new glass and reducing of the amount of modifiers a resistor system (FK 9600)was developed with high stability up to 200 deg C working temperature.