Microspring Characterization and Flip-Chip Assembly Reliability

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 μm) 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.

[1]  David K. Fork,et al.  Out-of-plane high-Q inductors on low-resistance silicon , 2003 .

[2]  Guilian Gao,et al.  Compliant Wafer Level Package for Enhanced Reliability , 2007, 2007 International Symposium on High Density packaging and Microsystem Integration.

[3]  Donald W. Brenner,et al.  The role of creep in the time-dependent resistance of Ohmic gold contacts in radio frequency microelectromechanical system devices , 2008 .

[4]  Muhannad S. Bakir,et al.  Sea of leads ultra high-density compliant wafer-level packaging technology , 2002, 52nd Electronic Components and Technology Conference 2002. (Cat. No.02CH37345).

[5]  Ashok V. Krishnamoorthy,et al.  Computer Systems Based on Silicon Photonic Interconnects A proposed supercomputer-on-a-chip with optical interconnections between processing elements will require development of new lower-energy optical components and new circuit architectures that match electrical datapaths to complementary optical , 2009 .

[6]  K. Van Schuylenbergh,et al.  Micro-spring force characterization and applications in integrated circuit packaging and scanning probe MEMS metrology , 2003, TRANSDUCERS '03. 12th International Conference on Solid-State Sensors, Actuators and Microsystems. Digest of Technical Papers (Cat. No.03TH8664).

[7]  Thomas Hantschel,et al.  Fabrication of highly conductive stressed-metal springs and their use as sliding-contact interconnects , 2003 .

[8]  D. L. Smith,et al.  A new flip-chip technology for high-density packaging , 1996, 1996 Proceedings 46th Electronic Components and Technology Conference.

[9]  K. Van Schuylenbergh,et al.  Wafer-Level Packaging With Soldered Stress-Engineered Micro-Springs , 2009, IEEE Transactions on Advanced Packaging.

[10]  Chuck Miller,et al.  Microspring contacts on silicon : Delivering Moore's law-type scaling to semiconductor package, test and assembly , 2000 .

[11]  John Maciel,et al.  Lifetime characteristics of ohmic MEMS switches , 2003, SPIE MOEMS-MEMS.

[12]  K. Van Schuylenbergh,et al.  Pressure Contact Micro-Springs in Small Pitch Flip-Chip Packages , 2006, IEEE Transactions on Components and Packaging Technologies.

[13]  Ashok V. Krishnamoorthy,et al.  Optical proximity communication , 2009, OPTO.

[14]  R. Ho,et al.  Novel packaging with rematable spring interconnect chips for MCM , 2009, 2009 59th Electronic Components and Technology Conference.

[15]  Bradley J. Nelson,et al.  Performance of microcontacts tested with a novel MEMS device , 2001, Proceedings of the Forth-Seventh IEEE Holm Conference on Electrical Contacts (IEEE Cat. No.01CH37192).

[16]  Thorsten Meyer,et al.  Bump wafer level packaging: A new packaging platform (not only) for memory products , 2003 .

[17]  E.M. Chow,et al.  Solder-Free Pressure Contact Micro-Springs in High-Density Flip-Chip Packages , 2005, Proceedings Electronic Components and Technology, 2005. ECTC '05..

[18]  T. Hantschel,et al.  Densely packed optoelectronic interconnect using micromachined springs , 2002, IEEE Photonics Technology Letters.