Design and fabrication of a micromachined bilayer cantilever probe card

Abstract

We present a bilayer cantilever microelectromechanical systems probe card configuration aiming to achieve an optimization of the mechanical and electrical properties of the probes. This bilayer cantilever structure is analyzed by an analytical method, and then further validated by finite element analysis. A prototype probe card structure is designed for the parallel I/O pads layout with a pitch of 100 µm, and developed via combining Si micromachining and ultraviolet Lithographie, Galvanoformung, Abformung (lithography, electroplating, and molding) (UV-LIGA) technique. The measured spring constant of the cantilever is 0.6362 Nm-1, close to the theoretical prediction. The resistance from the probe tip to the end of the Cu conductive line is as low as 0.035 , indicating a very small electrical loss on the probe structure. In the radio frequency (rf) range of 0 to 40 MHz, the characteristic impedance is higher than 20 k, while the capacitance between two adjacent probes is around 0.13 pF. These measurement data indicate that the designed cantilever probe card structure has a good rf isolation property that makes it suitable for the testing of high-speed signal ICs.