Rolling ball connector

US6177729A · kind A · utility

Assignee

• International Business Machines Corporation · US

Inventors

• Joseph A. Benenati · Hopewell Junction, US
• Claude L. Bertin · Venice, US
• William T. Chen · Endicott, US
• Thomas Edward Dinan · San Jose, US
• Wayne F. Ellis · Campbell, US
• Wayne J. Howell · Williston, US
• John U. Knickerbocker · Wappingers Falls, US
• Mark V. Pierson · Binghamton, US
• William R. Tonti · South Burlington, US
• Jerzy M. Zalesinski · South Burlington, US

Key dates

• Filing date: Apr 3, 1999
• Grant date: Jan 23, 2001
• Expiry date: Apr 3, 2019

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10T428/12472
• WIPO field: Semiconductors
• WIPO sector: Electrical engineering

Abstract

An integrated circuit assembly has pads of a chip electrically connected to pads of a substrate with rolling metal balls. A pliable material bonds the balls in movable contact with pads of the chip and substrate. Because the balls are relatively free to move, thermal expansion differences that would ordinarily cause enormous stresses in the attached joints of the prior art, simply cause rolling of the balls of the present invention, avoiding thermal stress altogether. Reliability of the connections is substantially improved as compared with C4 solder bumps, and chips can be safely directly mounted to such substrates as PC boards, despite substantial thermal mismatch.