Assembly Failure Mode Analysis

Problem:

Determine the preliminary failure mode for a manufacturer based on the attachment process being used.

Analysis:

X-ray is used to identify the quality of the solder joints and other possible areas of interest for the cross section analysis.

Cross sections of three key areas were made for further analysis. After careful review of the optical micrographs, one of the three samples warranted further imaging. SEM was used along with energy dispersive spectroscopy (EDS) to further analyze the solder joints determining that the quality base intermetallics formed during processing.

During the EDS of the solder joints some large areas of Copper-Tin intermetallics were noticed.

Problem Solved:

In the figure above, you can see that there are some large copper-tin intermetallic layers just above the nickel layer. Thus, the conclusion is that there are pinholes in the nickel layer that lead to copper-tin intermetallic areas. These large intermetallic regions will cause the joints to be significantly more brittle and lead to component failures.