A practical investigation on the root causes of the mechanical damages of pogo pin type test sockets to IC packages in final test

The root causes of the mechanical limitations are analyzed and their damages to the device-under-test (DUT) lead are demonstrated in this study. The evolution of microelectronics toward more densely packed contacts in a much smaller foot print has set a higher standard for the test socket used in the final test. This trend of evolution has brought several mechanical challenges for the pogo pin test socket, such as, (a) inability to overcome the trade off of the witness marks and contact resistance, (b) difficulties to target a specific contact area on a solder ball/unit leads when the pitches become too fine (c) difficulties in tolerance control as the pitch drops below 1.016 mm and (d) smaller metal contacts have lower fatigue life. All such problems are discussed here based on some experimental observations.