Importance

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Abstract

A ring-shaped, substantially planar structure is described for interposing between a chip and a substrate. The ring-shaped structure, being more flexible than a similar solid structure, conforms more readily to any irregularities in the surface of the substrate. Through holes in the planar structure facilitate controlled formation of reflow solder connections between the chip and the substrate. In one embodiment, the ring shape of the planar structure has a gap to facilitate better conformance to irregularities in the surface of the substrate and to minimize 'levering' of the chip. Other embodiments provide for 'kerfing' of the ring-shaped planar structure to permit even greater flexibility of the structure and less levering of the chip. Angled through holes permit adaptation of mismatched solder bump patterns on the chip and substrate. Other embodiments are directed to conductive elements embedded within the planar structure for making electrical contact with selected solder joints and/or to prevent electrogalvanic corrosion of solder bumps with different compositions.

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First Claim