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Electrical Wafer Sort process is known to induce stress in the pad structure and can lead to yield loss. In the present paper, probing simulation with Finite Element Method is performed and faced to experimental measurements. Firstly, the contact surface for planar and non-planar impacts and the needle structural lateral reaction force studies are carried out with static simulation. Then, using explicit solver, a calibration of the vertical and lateral reaction forces is performed for different over travel distances and needle geometries. Dynamical results of simulation are in good agreement with experimental measurements. The analysis shows that inertial effects during probing process remain limited. In addition to that, the measured force features are well reproduced by modeling, particularly the fine effects observed during the unloading stage. Finally, the effect of aluminium mechanical behavior is discussed by introducing permanent deformation ability of the pad.
Date of Conference: 10-12 Dec. 2007