Mechanical analysis of Ni alloys and W-Cu rolling pins for QFN test performance: a finite element approach

The test probe is a critical component in semiconductor packaging for wafer testing. Quad Flat No-Lead packaging is especially favored in modern electronic devices due to its compact size and improved thermal efficiency. Test probes are designed to accommodate chips of varying sizes and configurations. However, the continuous increase in chip operating frequencies has led to a rise in testing temperatures, which contributes to probe deformation. This deformation adversely impacts testing stability and ultimately reduces yield. This study introduces a composite material, W-Cu alloy, and designs a rolling pin structure to enhance stability, yield and test probe lifespan in Quad Flat No-Lead package testing. ANSYS is used to accurately model and simulate the behavior of the rolling pin, incorporating material properties, geometric dimensions and loading conditions. The analysis evaluates strain, stress distribution and deformation characteristics in both the rolling pin and the load board, aiming to understand the overall performance of the W-Cu rolling pin under real operating conditions. It is observed that, compared to Ni alloys, the mechanical properties generated by the W-Cu design in the load board show a decrease in equivalent stress, maximum shear stress and deformation by 8.60, 14.50 and 9.64%, respectively. Additionally, compared to Ni alloys, the strain of the W-Cu alloy increases by 10.60%, while total deformation decreases by 57.70%. Finally, the sliding contact distance is reduced by 58.00%. Based on these findings, a mechanism for managing stress, strain and deformation in the W-Cu structure is proposed.