Pockets of Contamination
This paper covers techniques for investigating pockets of contamination using a localized extraction method.
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Authored By:
Eric Camden
Foresite, Inc., Kokomo, IN USA
Summary
The areas of entrapment on cleaned and no-clean assemblies are showing higher levels of contamination around BGA's, in
microvias and particularly under components like the QFN. Flux residues trapped under and around low standoff components that are causing leakage paths are negatively impacting field performance, and are showing up as no trouble found return more often than ever. Microvias are corroding open during soldering due to the contamination from fabrication found in vias from the etch steps and poor cup rinsing of the plugged vias.
This paper will cover techniques for investigating pockets of contamination using a localized extraction method and ion chromatography analysis to establish root cause, and the development of corrective action plans for field failure projects. Defining, implementing and monitoring corrective action plans for the failed assemblies has allowed us to understand the processing variables, and optimize the critical parameters that meet the performance needs of today's technology.
Initially Published in the IPC Proceedings
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