Investigation of Cu wire neck crack under thermal cycling test

Copper wire is increasingly used in microelectronics because of its low cost, higher stiffness and better electrical and mechanical properties. However, there are some concerns on wire neck crack, wedge bond crack, and corrosion during reliability testing, especially wire neck crack under thermal cycling test (TCT). It is important to understand failure mechanism of Cu wire crack so that approach can be made for improvement to avoid Cu wire neck crack. In this study, simulation is conducted to investigate effect of CTE, modulus, Tg and adhesion on Cu wire neck crack, which explains different level of Cu wire neck crack with different molding compounds. With considering dominant factors of CTE mismatch and adhesion, appropriate molding compound with low CTE to match CTE of Cu wire as possible and also high adhesion with Cu wire can be used to solve Cu wire neck crack issue.