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Deformable Lid Design for Organic Double and Quad Chip Modules Disclosure Number: IPCOM000196498D
Publication Date: 2010-Jun-03
Document File: 4 page(s) / 65K

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A deformable lid design for organic double and quad chip modules is described.

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In the fabrication of either a dual chip module (DCM) or a quad chip module (QCM) on an organic substrate, variation in the z height exists in the region where the modules are bonded to the substrate. Moreover, once the chipsets are bonded to the substrate, the tolerance stack-up in the chips results in a sizeable (up to approximately 50 um) z height variation. This variation cannot be overcome by the flat lid, resulting in an increased thermal resistance of the TIM1 depending on the thickness of the TIM1 at the individual chip/lid interface. IBM* has not been able to implement QCM on an organic substrate due to low yields (chip cracking due to height variation in the chipset). During the sizing of various computer systems, QCM options were dropped as the yield was < 13%. Consequently, chipsets are single chip modules. The only known solution at present is to sort the chips based on thickness in order to minimize the tolerance stack. This reduces chip yield as those chips found to be in excess of the allowable thickness are relegated to low performance or single chip products.

    The lid is mated to the chips of a QCM using the following tool design. A push plate is in contact with a quadrant defined by the picture frame such that the face of the push plate is centered over and occupies > 95% of the quadrant area. Although the diagram shown in Figure 1 illustrates a single push plate in contact with one quadrant of a QCM lid, the tool would consist of four identical push plates in contact with the lid, one in each quadrant. Each push plate is connected to a rigid cylinder which is driven by either an electromechanical or servo hydraulic controller. Compressive force is monitored via either a strain gauge or load cell. The force applied to each push plate is controlled by the ASIC in a feedback loop to the drive mechanism. The ASI...