Analytical Techniques to Identify Unexpected Contaminants on Electronics Assemblies

This article is based on an original publication by STI.

Particulates and other contaminants on an electronic assembly or its related components can have a devastating effect on system integrity. It is essential that these materials are rapidly isolated, identified and removed so that corrective steps can be taken.

With a variety of examination and testing equipment, STI's Analytical Lab is equipped to evaluate both particulate and amorphous contaminants through Ion Chromatography (IC), Scanning Electron Microscopy with Energy Dispersive Spectroscopy capability (SEM/EDS), and Fourier Transform-Infrared Spectroscopy (FTIR).

Ion Chromatography
Generally a safe, non-destructive process when performed in accordance with the appropriate regulations, IC testing accurately detects and quantifies even minute amounts of cations, anions and weak organic acids. Suggested ionic contamination levels are listed below. (Chart does not include fluoride, malate, calcium, and magnesium, all of which are also detected through IC testing.)

Anions Washed Samples No Clean Samples
Chloride <6 <3-5
Nitrate <3 <3
Sulfate <3 <3
Bromide <10 <10
Nitrate <3 <3
Phosphate <3 <3
Weak Organic Acids Washed Samples No Clean Samples
Acetate <3 <3
Formate <3 <3
MSA, Adipic, Succinic <25 Total <125
Cations Washed Samples No Clean Samples
Lithium <3 <3
Sodium <3 <3
Ammonium <3 <3
Potassium <3 <3

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