Geometric parameter design of a cantilever probing needle used in epoxy ring probe card

In wafer probe card fabrication, contact force and forward displacement of needle tip are both important considerations affecting the probing results critically. This study establishes a finite element model of a cantilever probing needle used in epoxy ring probe card, to explore the effects of needle geometric parameters and probing overdrive upon the needle tip situation. Taguchiʹs methodology is used to derive the optimal parameter selection. Analytical results show that factors of taper length and needle diameter are the most influential in contact force, and the force can be controlled by the horizontal distance of cantilever measured from the needle tip to the epoxy fixed end. As for the forward displacement of the needle tip, both of taper length and cantilever horizontal distance are significant, and the probing displacement of the needle tips could be validly adjusted by the factors of bending angle and insert angle. A real experimental card has been made to verify the analytical results. Related materials can be provided as effective references in probe card design.