J031051 低応力三次元フリップチップ実装構造の検討([J03105]電子情報機器,電子デバイスの強度・信頼性評価と熱制御(5))

概要

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Local large residual stress and local deformation appears clearly in area-array flip chip structures because of the difference in material properties such as Young's modulus and the coefficient of thermal expansion among a bump, underfill, and a silicon chip. Because such large residual stress and the local deformation deteriorate the reliability of electronic devices, they should be minimized for improving the reliability of products. In addition, the material properties of electroplated copper bumps were found to vary depending on their electroplating conditions and thermal history after the electroplating. Therefore, the authors measured the residual stress and the local deformation in a chip considering the influence of the material properties of electroplated copper bumps by using piezoresistive strain sensor chips. As a result, it was found that the amplitude of the local distribution of the residual stress reached about 100 MPa and the local deformation of about 650 nm remained on the back surface of mounted flip chip. It was also found that the local deformation decreased from 650 nm to 100 nm by annealing of copper bumps. Therefore, the mechanical properties of electroplated copper bumps influence the residual stress and the local deformation.
一般社団法人日本機械学会の論文
2011-09-11