Construction and validation tests of a micro-impression creep test machine
نویسندگان
چکیده
A micro-impression creep machine was designed and developed, adopting a small punch in diameter of 150 um, displacement gage with sub-μm-scale accuracy, and a load-cell with mN-scale accuracy of in an effort to investigate the creep behavior of a small solder ball with a diameter of less than 1 mm. The creep behavior of a lead-free solder ball (Sn-3.0Ag-0.5Cu) with a diameter of 760 μm was investigated in the stress range of 8 to 60MPa and in the temperature range of 303K to 393K. We verified the appropriate performance of the developed machine by comparing the creep data from the self-made testing device to previously reported data for a magnesium alloy (AZ31). The stress exponent n for the solder ball sample was 3.7 in an intermediate stress range at 348K, indicating that glide of dislocations dragging in a solute atmosphere is the dominant creep deformation mechanism. The developed testing machine can be expected to find use in evaluating the creep strength of microelectronic solder joints.
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