Beyer Weaver & Thomas LLP
Integrated assembly-underfill flip chip process
Provided are flip chip device assembly methods that integrate the solder joining and underfill operations of the assembly process. Solder joining of the die and substrate and curing of the underfill material between the die and substrate is accomplished in the same heating and cooling operation. As a result, the coefficient of thermal expansion (CTE) mismatch stresses incurred prior to application and curing of underfill by a device packaged according to the conventional technique having a separate heating and cooling operation following solder joining, are avoided. These stresses are of particular concern in smaller device size technologies (e.g., 0.13 microns and smaller) using low k dielectrics and large die sizes due the difference in CTP between the die and substrate.
Altera Corporation
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Wen-chou Vincent
Wang