Recent post-reflow cleanliness testing demonstrated contamination on some assemblies. Is there a way to control cleanliness in the defluxing process in order to assure a predictable outcome?

It happens every day in high reliability electronic assembly. Boards are assembled, reflowed, cleaned and then a random sample assembly is subjected to cleanliness verification.

If, after testing, the board tested demonstrated at least a specific level of cleanliness, the cleanliness process is deemed a success. If however, the sampled board failed cleanliness testing, an entire lot of boards is now suspect and a line is potentially down.

While post-cleaning cleanliness testing is a valuable resource, the sole reliance on such a procedure is like waiting for your bumper to strike the car behind you before applying the breaks.

Just as modern automobiles with advanced sonar-based parking systems eliminate “fender-benders”, modern defluxing systems that are equipped with “predictive cleanliness technology” reduce or eliminate post-defluxing cleanliness failures.

A defluxing system equipped with predictive cleanliness testing capabilities will monitor the real-time cleanliness of a load of assemblies. The predictive cleanliness testing feature will constantly compare the real-time cleanliness with the operator’s programmed cleanliness. When the load of assemblies is determined to be at or above the operator’s preset cleanliness level, the defluxing system will terminate the cleaning cycle automatically, ensuring satisfactory cleanliness levels.

Although randomly sampled assemblies subjected to a post-clean resistivity of solvent extract (ROSE) or ion chromatography (IC) test should not be discontinued, the implementation of predictive cleanliness technology within a defluxing process will make cleanliness failures extremely rare indeed.