SMTA International Conference Proceedings


MICROSTRUCTURAL EVOLUTION OF SN-AG SOLDER JOINTS RESULTING FROM SUBSTRATE COPPER DISSOLUTION

Author: Srinivas Chada
Company: Marquette University
Date Published: 9/12/1999   Conference: SMTA International


Abstract: Studies of the effect of Cu substrate dissolution on the microstructure of solder joints were carried out using samples reflow soldered isothermally at various temperatures and times. Light (LM) and scanning electron microscopy (SEM) as well as energy dispersive spectroscopy (EDS) were used to study the microstructural evolution. All samples were found to exhibit highly inhomogeneous, non-equilibrium microstructure. Analysis of some of these samples showed that the Cu concentration, the volume fraction of primary Sn-dendrites and n(Cu6Sn5) intermetallics in the solder increased with reflow temperature and time as a result of Cu dissolution. In addition, the relative amount of eutectic decreased with increasing time and temperature. Sn-Ag-Cu ternary phase diagram along with vertical sections at various constant Cu concentrations was constructed to explain the observed microstructure.

Key words: Cu substrate, Sn-Ag solder, non-equilibrium microstructure, Cu-Sn intermetallics, Sn-Ag-Cu ternary phase diagram.



Members download articles for free:

Not a member yet?

What else do you get when you join SMTA? Read about all of the benefits that go along with membership.

Notice: Sharing of articles is restricted to just your immediate work group. Downloaded papers should not be stored on an external network or shared on the internet.


Back


SMTA Headquarters
6600 City West Parkway, Suite 300
Eden Prairie, MN 55344 USA

Phone +1 952.920.7682
Fax +1 952.926.1819