A new method for preventing stress cracking in repairable ceramic packages by changing the sealing ring shape

Abstract

High-reliable ceramic packages are impressionable to the parallel seam welding (PSW) parameters leading to low yield and reliability. In this study, the structure of the ceramic package was modified by changing the sealing ring to improve weldability and high-temperature reliability. Three types of ceramic packages with different-shaped sealing rings, which are conventional rectangular rings, notch inward rings, and notch outward rings, were fabricated by Au-Sn soldering and a follow-up PSW process. The packages with the rectangular ring failed in the subsequent high-temperature aging test. The packages with the notch inward ring exhibited an early failure after PSW. Cracks were generated in the Au-Sn solder and propagated into the ceramic substrate. The packages with the notch outward ring exhibited remarkable weldability and reliability. Sequential thermo-structural coupling was used to simulate the temperature and stress distribution in the packages. The maximum principal stress in the aforementioned ceramic substrates rapidly increased to approximately 170.0 MPa, 168.5 MPa and 101.4 MPa in the PSW process. Stress concentration existed at the outside corner around the rectangular and notch inward-shaped sealing rings. The maximum temperature at the local position in the ceramic was raised to 250.3 °C, 238.6 °C and 157.2 °C depending on the shape of the sealing ring. The extra transmission path in the notch outward ring relieved thermal mismatch and deformation at the Au-Sn/ceramic interface during PSW. The packages with notch outward rings were recommended especially in the repairable ceramic packaging.