THE PROBLEM:

A routine QA/QC check during the building of circuit boards revealed contaminated capacitors. The production line was forced to come to a halt until the cause of the contamination could be determined. This was a critical issue for the electronic assembly plant, and the contamination needed to be identified quickly, as ceasing production is very costly. That is when MVA Scientific Consultants was called in to perform a RUSH analysis on the capacitors in question.

THE ANALYSIS:

An initial examination of the capacitors revealed areas appearing “wet” (Figure 1) and there was concern that a solder flux residue was present. Further examination by stereomicroscopy  showed that the “wet” areas were in fact a dry, glossy, hardened substance. Examination by Fourier transform infrared spectroscopy (FTIR) of these “wet” areas indicated they were consistent with reference spectra of polystyrene (Figure 2), and not with abietic acid flux residue.

THE OUTCOME:

The “wet” appearing contaminant on the surface of the capacitor was polystyrene.  Its infrared spectrum was not consistent with flux residue. Based on the analytical results reported by MVA Scientific Consultants, the manufacturer was able to identify the source of the polystyrene and production resumed.