Effect of Composition and Cooling Rate on the Microstructure of SnAgCu-Solder Joints

Author

Mueller, M. ; Wiese, S. ; Roellig, M. ; Wolter, K.-J.

Author_Institution

Tech. Univ. Dresden, Dresden

fYear

2007

fDate

May 29 2007-June 1 2007

Firstpage

1579

Lastpage

1588

Abstract

In this study the solder alloys SnAg3.5, SnAg3.0Cu0.5, SnAg3.8Cu0.7 and SnAg2.7Cu0.4Ni0.05 have been analysed in order to determine variations in microstructure caused by cooling rate, solder composition and ball diameter. Solder spheres with a diameter of approx. Oslash 1100 mum, Oslash 590 mum, Oslash 270 mum and Oslash 130 mum were solidified with cooling rates of 0.14 K/s, 1.1 K/s and 10.9 K/s. Cross sections of these specimens were analysed by optical light microscopy. Interpretations of the analysed microstructure allow a description of the solidification process, which takes place in a solder ball. It could be concluded that this process is divided in three stages: the formation of primary intermetallics, the formation of fine structured regions and the formation of coarse dendritic areas.

Keywords

cooling; copper alloys; crystal microstructure; nickel alloys; silver alloys; solders; solidification; tin alloys; SnAg; SnAgCu; SnAgCuNi; ball diameter; coarse dendritic areas; cooling rate; fine structured regions; solder alloys; solder composition; solder joints microstructure; solder spheres; solidification process; Cause effect analysis; Electronics cooling; Environmentally friendly manufacturing techniques; Flip chip; Intermetallic; Lead; Metallization; Microstructure; Optical microscopy; Thermomechanical processes;

fLanguage

English

Publisher

ieee

Conference_Titel

Electronic Components and Technology Conference, 2007. ECTC '07. Proceedings. 57th

Conference_Location

Reno, NV

ISSN

0569-5503

Print_ISBN

1-4244-0985-3

Electronic_ISBN

0569-5503

Type

conf

DOI

10.1109/ECTC.2007.374006

Filename

4250092