Intermetallic reactions in a Sn-20In-2.8Ag solder ball-grid-array package with Au/Ni/Cu pads
Resource
Journal of Electronic Materials 34 (1): 1385-1390
Journal
Journal of Electronic Materials
Journal Volume
34
Journal Issue
1
Pages
1385-1390
Date Issued
2005
Date
2005
Author(s)
Abstract
The intermetallic compounds formed during the reflow and aging of Sn-20In-2.8Ag ball-grid-array (BGA) packages are investigated. After reflow, a large number of cubic-shaped AuIn2 intermetallics accompanied by Ag2In precipitates appear in the solder matrix, while a Ni(Sn 0.72Ni0.28)2 intermetallic layer is formed at the solder/pad interface. With further aging at 100°C, many voids can be observed in the solder matrix and at the solder/pad interface. The continuous distribution of voids at the interface of specimens after prolonged aging at 100°C causes their bonding strength to decrease from 5.03 N (as reflowed) to about 3.50 N. Aging at 150°C induces many column-shaped (Cu 0.74Ni0.26)6(Sn0.92In 0.08)5 intermetallic compounds to grow rapidly and expand from the solder/pad interface into the solder matrix. The high microhardness of these intermetallic columns causes the bonding strength of the Sn-20In-2.8Ag BGA solder joints to increase to 5.68 N after aging at 150°C for 500 h.
Subjects
Ball shear strength; Ball-grid-array (BGA); Intermetallic compounds; Sn-20In-2.8Ag solder
Other Subjects
Copper; Gold; Microhardness; Nickel; Precipitation (chemical); Soldered joints; Soldering alloys; Temperature distribution; Tin; Ball shear strength; Ball-grid array (BGA); Sn-20In-2.8Ag solder; Intermetallics
Type
journal article
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