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Application of deuterium oxide (D2O) isotope tracing technique for encapsulated QFN failure analysis

2022; Elsevier BV; Volume: 135; Linguagem: Inglês

10.1016/j.microrel.2022.114607

1872-941X

Liao Jinzhi Lois, Meng Tian, Yong Du, Qiang Ji, Lei Zhu, Xi Zhang, Hua Younan, Xiaomin Li,

High voltage insulation and dielectric phenomena

Polymer encapsulated components are universally used in consumable applications. However, polymer encapsulants for packages commonly are non-hermetic. The polymer encapsulants can absorb moisture from atmosphere which will post a risk to the package reliability. In this study, a type of polymer encapsulated Quad Flat No-Lead (QFN) package encountered electricity leakage after Highly Accelerated Stress Tests (HAST) 96 h. Although it is suspected that penetration of moisture into the encapsulated package caused electrical leakage failure, there is no direct evidence to prove this assumption. Traditional X-ray and Scanning Acoustic Microscopy (C-SAM) techniques cannot detect any defect of the package due to their detection limit. To solve above issues, this study employed a new deuterium oxide (D2O) isotope tracing method. The encapsulated package underwent highly Accelerated Stress Tests (HAST) with D2O, and D signal of the sample was analysed by Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS). The results showed that D localized at the failure area where leakage occurred. It is direct evidence to show it is a moisture-induced leakage.