The Dirty Dozen
Twelve Common Mistakes Made When Cleaning Circuit Boards

Mike Konrad
Founder / CEO
Aqueous Technologies

 Presentation Abstract

As electronic assemblies become smaller, denser, and more frequently deployed in harsh operating environments, the margin for contamination-related failures continues to shrink. 

While post-reflow cleaning has long been part of electronics manufacturing, many cleaning processes are still built on assumptions rather than validated controls. These assumptions can lead to residues remaining under low-standoff components, inadequate removal of flux activators, poor rinsing, trapped moisture, and unreliable cleanliness data.

This paper examines “The Dirty Dozen,” twelve common mistakes made when cleaning circuit boards. These mistakes include assuming no-clean fluxes never require cleaning, failing to define “clean enough,” relying too heavily on visual inspection or ROSE testing alone, selecting incompatible cleaning chemistries, overlooking component geometry, and neglecting process monitoring. Each mistake is discussed in the context of modern assembly challenges, including miniaturization, bottom-terminated components, high-reliability applications, and exposure to temperature, humidity, and electrical bias.

The objective of this paper is to help manufacturers move from assumption-based cleaning to evidence-based process control. By understanding these common errors and their consequences, manufacturers can improve cleaning effectiveness, reduce contamination-related reliability risks, and better align their cleaning process with the performance requirements of the finished assembly.