Micro-bumps to enhance LGA interconnections
AssigneeInternational Business Machines Corporation
InventorsJeffrey A. Brody, Hsichang Liu, Hai Pham Longworth, James C. Monaco, Gerard J. Nuzback, Wei Zou
Life of this patent
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Abstract
An improved Land Grid Array interconnect structure is provided with the use of small metal bumps on the substrate electrical contact pad. The bumps interlock with segments of the fuzz button connection and increase the physical contact surface area between the contact pad and fuss button. The improved contact reduces displacement of electrical contact points due to thermo-mechanical stress and lowers the required actuation force during assembly.
Claims10
A method for creating micro-bumps on metal contact pads comprising the steps of:
- providing a plurality of glass ceramic greensheets,
- stacking said plurality of glass ceramic greensheets, said stack of glass ceramic greensheets having a bottom surface glass ceramic greensheet layer containing bottom surface metal contact pads, wherein the metal contact pads have an exterior surface extending beyond the bottom surface glass ceramic greensheet layer,
- providing an alumina contact sheet having through holes, said through holes configured to the location and pitch of the desired micro-bumps,
- placing said alumina contact sheet first in contact with said metal contact pad exterior surface and subsequently forcing the alumina contact sheet into contact with said bottom surface glass ceramic greensheet layer thereby extruding at least a portion of the metal contact pad into the through holes to form micro-bumps on the metal contact pad exterior surface, and
- laminating said stack of glass ceramic greensheets and contact sheet to create a laminate.
A method for creating micro-bumps on metal contact pads comprising the steps of:
- providing a plurality of alumina ceramic greensheets,
- stacking said plurality of alumina ceramic greensheets, said stack of alumina ceramic greensheets having a bottom surface alumina ceramic greensheet layer containing bottom surface metal contact pads, wherein the metal contact pads have an exterior surface extending beyond the bottom surface alumina ceramic greensheet layer,
- providing a metal plate having through holes, said through holes configured to the location and pitch of the desired micro-bumps,
- placing said metal plate first in contact with said metal contact pad exterior surface and subsequently forcing the metal plate into contact with said bottom surface alumina ceramic greensheet layer thereby extruding at least a portion of the metal contact pad into the through holes to form micro-bumps on the metal contact pad exterior surface, and
- laminating said stack of alumina ceramic greensheets and metal plate to create a laminate.
Dependencies are inferred from the claim text.