Selecting Reference Materials for FTIR Analysis of PCB Residue

FTIR analysis can help identify an organic residue, but a useful investigation needs appropriate reference material and process context. A library match is a lead to evaluate. It should not automatically become a claim that a named supplier’s product caused the observed failure.

Explain the physical question to the laboratory

Identify where the residue appears and which process materials could have reached that location. Preserve the original board condition and provide photographs. Agree on whether analysis will occur directly at the site or on a collected sample before any cleaning or scraping changes it.

Bruker’s electronics analysis overview describes FTIR microscopy for soldering and washing residues and the use of reference libraries in particle investigations. The technique supplies chemical evidence that should be interpreted together with the assembly’s actual materials and processing history.

Build a relevant reference set

Select references with the analyst rather than sending an indiscriminate collection. Label each sample with its identity and treatment so the comparison does not lose the distinction between raw and processed material.

Keep mixtures and local variation visible

A residue may contain more than one material. Ask which spectral features support the proposed identification and what remains unexplained. Several locations may need comparison when appearance or manufacturing exposure differs across the board.

For example, a cured adhesive at a bond edge may differ from an uncured drop retained from the container. A poor match to the raw material does not resolve whether processing changed the relevant signature.

Record any collection solvent, tape or tool used in sampling. Its contribution should be distinguishable from the unknown residue, especially when only a small amount is available.

Test the proposed source against the route

After identifying a plausible material family, determine how it could have reached the affected region. Compare unaffected boards and relevant process stages. Chemical similarity supports a hypothesis but does not establish the transfer event by itself.

Keep the original spectra and analyst’s interpretation with the failure record. A short conclusion such as adhesive contamination can discard uncertainty needed for later review.

The SEM-EDS comparison guide addresses elemental evidence, while localized extraction planning addresses soluble ionic material from a defined board region.