Contact Resistance and Current De-rating in Power Interconnects

Thermal Challenges in Power Distribution

Modern electronic systems compress high power density into small form factors. Delivering 10 A to 30 A from power supply modules across board-to-board or wire-to-board connectors generates localized heat due to electrical contact resistance at mating pin interfaces.

Excessive junction heating causes connector housing degradation, contact oxidation, and thermal runaway.

Factors Influencing Connector Current Ratings

1. Contact Resistance: Every mated pin pair exhibits micro-ohms of resistance driven by surface roughness, contact pressure, and material plating. Higher current flow through this resistance generates heat proportional to the square of the current.
2. Temperature Rise and De-rating Curves: Manufacturer current ratings are typically calculated at room temperature in open air. When connectors operate inside closed enclosures or elevated ambient temperatures, their allowable current capacity must be de-rated according to thermal curves.
3. Pin Multiplicity and Airflow: Grouping multiple power pins together reduces airflow and increases thermal concentration. Apply a de-rating factor of 20 to 30 percent when running maximum continuous current through multiple adjacent pins simultaneously.