One step method for curing and joining BGA solder balls
AssigneeInternational Business Machines Corporation
InventorsPatrick A. Coico, James H. Covell, Lewis S. Goldmann, Kimberly A. Kelly
Life of this patent
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Abstract
A one step method for curing encapsulant and joining Ball Grid Array (BGA) solder balls comprises curing an encapsulant material simultaneously with the joining of the eutectic material of the apparatus whether that eutectic material is a solder paste or preform, the balls being of a higher melt material or the balls themselves being an eutectic material. The method performs both functions in one pass through a furnace avoiding the separate and time consuming encapsulant and/or underfill curing step.
Claims14
A method for building an electronic chip carrier comprising the steps of:
- electronically attaching at least one chip to a first side of a substrate with at least one first conductive material;
- filling an area between said chip and said first side of the substrate with at least one encapsulant underfill material;
- depositing at least one second conductor material on an underside of said substrate;
- and
- heating at a temperature to effect curing said underfill material between said chip and said first side of said substrate simultaneously with said at least one second conductor material on the underside of said substrate, but at a temperature below the reflowing temperature of said at least one first conductive material.
A method for building an electronic chip carrier comprising the steps of:
- electrically attaching at least one chip to a first side of a substrate with at least one first conductive material to provide a first subassembly;
- filling a space between said chip and said first side of the substrate with at least one encapsulant underfill material;
- electrically attaching a plurality of conductive balls to an underside of said substrate while simultaneously curing said at least one encapsulant underfill material to provide a second subassembly by heating at a temperature sufficient to effect curing said underfill material and reflowing of the conductive balls but at a temperature below the reflowing temperature of the at least one first conductive material;
- and
- attaching a cap to said second subassembly over said at least one chip.
Dependencies are inferred from the claim text.