Solder-free pressure contact micro-springs in high-density flip-chip packages
This work investigates electrical pressure contacts based on a micro-spring with orders of magnitude smaller pitch and force than conventional pressure contacts. Flip-chip packages were assembled with hundreds of micro-springs at 20 um pad-pitch, 40 um spring-pitch, and an operating force of 0.01 gram on gold pads. These packages are shown to have stable resistance values during both thermocycle (0° C -125° C) and humidity testing (60° C at 95% RH). High-speed glitch measurements are performed to confirm the pressure contact does not have intermittent opens during thermocycling. These results suggest that a low-force solder-free pressure spring contact is a viable technology for next generation flip-chip packaging.
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Chow, E. M. ; Chua, C. L. ; Hantschel, T. ; Van Schuylenbergh, K. ; Fork, D. K. Solder-free pressure contact micro-springs in high-density flip-chip packages. Proceedings of the 55th Electronic Components and Technology Conference; 2005 May 31- June 3; Lake Buena Vista; FL. Piscataway, NJ: IEEE; 2005; 1119-1126.
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