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(Color online) (a) A schematic diagram of the cross-section of the solder joint, showing the configuration and dimensions of the sample. (b)-(d) The cross-sectional slices reconstructed by SRCL of the sample I at the interface between the solder ball and UBM before, after 13 h, and 77 h of EM test, respectively, under a current density of 7.5 × 103 A/cm2 at 125 °C. (e)-(g) Cross-sectional slices of the sample II, before, after 13 h, and 77 h of EM test, respectively, under a current density of 1 × 104 A/cm2 at 125 °C.
(Color online) (a) The linear relationship between of sample I (stressed by 7.5 × 103 A/cm2 at 125 °C) and sample II (stressed by 1 × 104 A/cm2 at 125 °C), respectively, fitted by JMA-like model. The slope of the linear line is n (mode of void growth), while the intercept of the line is . The parameters of n and of both the samples by fitting the JMA-like model are given in Table I. (b) The distribution of the time to failures (TTFs) measured from two groups of solder joints tested at 125 °C by 7.5 × 103 A/cm2 and 7.5 × 103 A/cm2, respectively. The shape parameters and characteristic lifetime of them fitted by Weibull distribution are also given in Table I.
A summary of the parameters of n, τ, β, and η fitted by JMA-like model and Weibull distribution and semi-theoretical values of τ derived by the Black’s equation under two EM test conditions.
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