Meaning
Microscopic wear at the contact interface of spring-loaded test pins caused by vibration and thermal expansion leads to the accumulation of resistive debris. This degradation, known as pogo pin contact fretting, occurs when the small movements between the pin tip and the test pad wear away the protective gold plating. It increases the contact resistance, resulting in false failures during automated board testing.
The phenomenon is bounded by the life expectancy of the pin spring and the plating thickness.
Wear Mechanism
Fretting wear is accelerated by the mechanical vibrations of the test fixture and the thermal expansion of the board during testing. The relative motion between the pin and the pad exposes the base metal, which oxidizes rapidly. This oxide layer acts as an insulator, disrupting the signal path.
Contact Degradation
Contact resistance rises from a few milliohms to several ohms as the oxide debris builds up. This change can trigger false errors in voltage, current, or signal integrity measurements. Technicians must frequently clean or replace the pins to maintain test fixture accuracy.
Proper cleaning schedule design minimizes the downtime of the test line and prevents the rejection of good boards.
Material Remedy
Plating the pins with harder metals like rhodium or using specialized tip geometries can reduce the rate of wear. These solutions extend the maintenance interval of the test fixture. This ensures continuous operation of the production line.
