Case 2193 ยท Public preview
Thermal Fatigue Can Combine CTE Mismatch, Grain Growth, and Gold-Rich Solder
Microsectioned J-lead solder joints showed fatigue cracking and fracture after service exposure, raising concern that gold embrittlement had reduced their fatigue resistance.
Metallographic microsectioningBSE SEMEDSMicrostructural comparisonImage analysis
What the evidence preview establishes
The thermal-fatigue damage was most consistent with three contributing factors: CTE mismatch between the J-lead package and alumina substrate, time-temperature exposure that coarsened the solder microstructure, and Au-Sn intermetallic content near the accepted threshold for gold embrittlement.
Why this case matters
Treat solder fatigue as a system interaction. Fracture morphology establishes cyclic damage, a new-to-aged microstructural comparison reveals time-temperature exposure, and gold content indicates whether metallurgical embrittlement reduced the margin available to absorb CTE-driven strain.
Full evidence reserved for MEMBER and STOREThe complete case includes the evidence sequence, 4 interpreted figures, alternative explanations, limitations, and practical application guidance.