B. Cheng, D. De Bruyker, C. Chua, K. Sahasrabuddhe, I. Shubin, J. E. Cunningham, Y. Luo, K. F. Böhringer, A. V. Krishnamoorthy, E, M. Chow; IEEE
Electronics packaging based on stress-engineered spring interconnects has the potential to enable integrated IC testing, fine pitch, and compliance not readily available with other technologies. We describe new spring contacts which simultaneously achieve low resistance (< 100 mΩ) and high compliance (> 30 �m) in dense 2-D arrays (180 ~ 180-µm pitch). Mechanical characterization shows that individual springs operate at approximately 150-µN force. Electrical measurements and simulations imply that the interface contact resistance contribution to a single contact resistance is < 40 mΩ. A daisy-chain test die consisting of 2844 contacts is assembled into flip-chip packages with 100% yield. Thermocycle and humidity testing suggest that packages with or without underfill can have stable resistance values and no glitches through over 1000 thermocycles or 6000 h of humidity.
This paper suggests that integrated testing and packaging can be performed with the springs, enabling new capabilities for markets such as multichip modules.
SMTA - Surface Mount Technology Association is a non-profit international association of companies and individuals (totalling 4,000) involved in all aspects of advanced electronics assembly, surface mount and related technologies.
IPC - Association Connecting Electronics Industries is a US-based trade association dedicated to the competitive excellence and financial success of its nearly 2,600 member companies which represent all facets of the electronic interconnection industry, including design, printed wiring board manufacturing and electronics assembly.