scope:

Abstract:

A crack in an RF circuit ceramic substrate was revealed by a potentially mission catastrophic loss of output power during thermal-vacuum test of a sensor module. This crack was due to substrate weakening caused by use of a dental drill used for circuit tuning (by removing conductor material) during the final amplifier assembly process. Microwave RF circuit design that involves the practice of flight unit tuning by removal of conductive material, such as by use of abrasive or cutting tools, should be compatible with the substrate and circuit material, the packaging design, and other relevant factors. The Lesson Learned and Recommendations section in this 1977 lesson learned were revised in 2006 to reflect current practice in the use of abrasive and cutting tools to tune RF circuits.