Patent ID: 6815831
Filing Date: 2004-11-09
Classification: H01L

Abstract:
A device, comprising:a die having one or more flip chip bumps on a surface thereof, each bump having a bump surface distal to the die surface; a plurality of filled underfill layers successively disposed upon the die surface, an initial filled underfill layer having a greater coefficient of thermal expansion than the die surface and each subsequent filled underfill layer having a greater coefficient of thermal expansion than a preceding filled underfill layer, the plurality of filled underfill layers and the bump surfaces planarized; and a layer of unfilled underfill disposed upon a topmost filled underfill layer of the plurality of filled underfill layers such that none of the filled underfill layers extends above the bump surfaces, and such that the layer of unfilled underfill has a coefficient of thermal expansion greater than the topmost filled underfill layer.