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Method for high-temperature reflow carrier studs used to create a fixed minimum BGA solder-joint stand-off height between the substrate and the interposer

IP.com Disclosure Number: IPCOM000010330D
Publication Date: 2002-Nov-20
Document File: 4 page(s) / 84K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for high-temperature reflow carrier studs used to create a fixed minimum ball-grid array (BGA) solder-joint stand-off height between the substrate and the interposer. Benefits include improved reliability and improved design flexibility.

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Method for high-temperature reflow carrier studs used to create a fixed minimum BGA solder-joint stand-off height between the substrate and the interposer

 

Disclosed is a method for high-temperature reflow carrier studs used to create a fixed minimum ball-grid array (BGA) solder-joint stand-off height between the substrate and the interposer. Benefits include improved reliability and improved design flexibility.

Background

              BGA solder joints with a fixed minimum stand-off height are used to place land-side capacitors directly underneath the die on the underside of the substrate package. Reliability problems are encountered when the package collapses directly on the capacitors during reflow (see Figure 1). Conventionally, these problems are addressed by combining 10Sn/90Pb solder-alloy balls or bumps with a 63Sn/37Pb solder alloy paste. The 10Sn/90Pb solder alloy does not liquefy during reflow while the 63Sn/37Pb solder alloy does liquefy.

General description

              The disclosed method is the use of studs on high-temperature reflow carriers to create a fixed minimum BGA solder-joint stand-off height between the substrate and the interposer (see Figure 2). 

              The key elements of the method include:

•             Process of record (POR) high-temperature reflow carrier that has recesses for substrate part placement to which four cylindrical or rectangular studs are welded and then precision ground to a predetermined height

•             Round notches in the interposer edge that enable studs to pass by the interposer and rise to a height greater than the top surface of interposer surface...