Failure analysis of the adhesive joint of microwave ferrite phase shifter

Failure investigation is carried out on the adhesive joint of microwave ferrite phase shifter. Though, practically, the failure mode of microwave ferrite phase shifter can be described as the fracture of adhesive joint between ferrite and microwave dielectric ceramic, the failures of adhesive layer could be found in various ways and at various stages of manufacture, assembly and service. They may be due to the strength degradation caused by moisture environment, or the voids defects originated from dehydration effect of the adhesive as well as the contamination during manufacturing. With the help of SEM, FTIR and TGA, both the normal and failed samples of microwave ferrite phase shifter were selected, compared and analyzed. Recommendations for the structural design and the adhesive process are presented, and the responsibility of the failures was charged to the negligence of the manufacturer of the microwave ferrite phase shifters.