First, it is important to know whether the objective of the analysis is to measure the total amount of the two metals in the assembly as a whole, or to measure their proportions in each of the different areas; the tin solder, the intermetallic layers and so on. The purpose to which the results are to be put is also important. To some extent the answer depends on knowing this, as a biased but highly repeatable measure of something is often useful for internal purposes.

For Au/Sn intermetallic compounds which have quite specific compositions, the absorption/enhancement effects will be different than for a low-concentration solid solution of either of the metals in the other.