Failure Analysis Case Study of MLCC Component Crack with Application of FEA and Bend TestAuthors: Henley Zhou, Kerwin Wang, Billy Liu, Jimmy Chen, Apitak Promson, Arnel Camacho, Alex Xie, Michael Sumalinog, Ranilo Aranda, GP Li, RSivam VRajoo, Mike Doiron
Date Published: 8/28/2017 Conference: SMTA China
Unlike the other MLCC assembly defects, cracks are normally not visible making it difficult to find. The soldering process, raw materials, environment, tools and fixturing are all possible sources of the problem. To narrow down the study, we will be looking into the effect of two major factors on MLCC cracking which is thermally induced stress and mechanical induced stress by board flexing.
This paper will tell a story of a real case failure analysis for 0603 MLCC component crack. The failure was confirmed crack by cross section analysis of the failed unit and suspected to be due to high mechanical stress during the PCBA assembly process. The strain gage testing (SGT) was performed but cannot identify which process contributes to the defect as all strain measured are within the allowable limits. From this, thermal stress was also become a suspect. To simulate the failure, Finite Element Analysis (FEA) was used and correlate the result to the actual defect based on crack pattern and locations. FEA simulation result that the actual crack pattern matched with the mechanically induced stress. Due to different electrode patterns design that each supplier may use, bend test using a simple test vehicle was also done to identify which vendor can supply the most reliable component.
MLCC, thermal stress, mechanical stress, SGT, FEA, bend test
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