Case 2220 ยท Public preview
Surface Residue and Section-Preparation Artifacts Can Complicate Solder Chemistry
Selected solder joints on two assemblies had a gray or grainy appearance and were examined at the surface and in microsection.
BSE SEMSurface EDSMicrosectioningSection EDSSurface-to-section comparison
What the evidence preview establishes
The appearance was attributed to a surface film containing tin-lead oxides and silicon, likely associated with silicone contamination. Copper detected after sectioning required separate consideration as possible preparation drag-in rather than original residue chemistry.
Why this case matters
Compare the original surface with the prepared section before assigning unexpected elements to the assembly process. Retain location images with spectra, check for polishing transfer, and confirm suspected organic contamination by an appropriate chemical method when identification is important.
Full evidence reserved for MEMBER and STOREThe complete case includes the evidence sequence, 4 interpreted figures, alternative explanations, limitations, and practical application guidance.