Microstructures and Electrical Properties of Tin Oxide Formed Under Fretting Conditions

Large quantities of Sn and O (contaminated with C) were found to accumulate on the contact surface of pogo pins after about 50,000 test cycles. Sn appears to be transferred and then oxidized, resulting in the increase of contact resistance(Rc) of pogo pins. The electrical resistivity of sintered SnO₂ thick films was found to increase, as the temperature decreased below 20degC . This fact may explain higher contact resistance(Rc) measured at the low-temperature tests. However, after Sn was transferred, how it was oxidized and whether the Sn oxide was SnO or SnO₂ (or mixed) are yet unclear. Detailed fretting corrosion processes are now under investigation.