Effects of material and process on the reliability of very small hermetic microwave packages

Three very small microwave packages have been designed and fabricated. The hermeticity performance and reliability of these packages were evaluated. Package A has brazed leads and hence superior lead strength (lead tension and lead fatigue), but poor and inconsistent hermeticity yields. The leads of package B are sandwiched between the base and lid using the solder glass, so that the lead strength is not as good as that of the brazed leads. Furthermore, the sealed package is more susceptible to handling-related problems. The bending process caused microcracks along the sealing glass, which deteriorate the hermeticity of the package. The package C design incorporated the package A design and the side braze package design. The reliability of this package meets the JAN-S requirements as well as other military standard specifications. The performance of the package is also acceptable for high-frequency microwave applications. The results indicate that packages designed with closely matched coefficient of linear thermal expansion materials provide reliable hermetic packages