Determination of Friction Coefficient of a Press-Fit Pin in Thin Plating

To determine the friction coefficient of a press-fit pin in thin plating, both experiments and three-dimensional finite element analysis are carried out. The compliant press-fit pins are assembled into printed circuit boards with two types of plated through holes, one is Cu and Sn plated and the other only Cu plated, and the load-displacement relationships of the pin during assembly are recorded. Based on the load-displacement relationships of the pin obtained experimentally and the nodal reactions of the pin contacting with the plated hole, obtained from numerical analysis, performed assuming a fiction-less condition, the friction coefficients of the pin in plated holes during assembly are successfully determined. The friction coefficient of the pin in the Sn/Cu plated hole exhibits a higher value than that for the Cu plated hole during assembly, due to the adhesion in the contacting region. In an attempt to check the validity of the determined coefficients of friction, different press-fit assemblies are considered, and the load-displacement relationships of the pin are predicted. The simulations are found to be in good agreement with experimental measurements. The retention forces between the pin and the plated holes are also predicted.