Failure Analysis of Contact Probe Pins for SnPb and Sn Applications Available to Purchase

A failure mechanism of pogo-type probe pin is investigated. A probing tester with actuation capable in three-axes is used to simulate the actual inspection process experimentally. Force required to break in surface oxides and develop electrical contact is measured. Contact resistance history reveals that pins mating to Sn surfaces fail earlier than SnPb surfaces. Through periodic inspection of pin using microprobe/EDS as a function of probing count, the general root cause of pin failure is turned out to be pin tip wear out associated with Sn oxide growth on its surface. The cause of earlier failure of the pin probing matte Sn surface is identified as severe wear out by a rough and abrasive characteristic of matte Sn.