Authored By:
Corey Peterson
Rockwell Automation
Mequon, WI, USA
Summary
Ultraviolet (UV) curable coatings can be used to meet cost pressures and for improved coating performance when compared to other coating material. However, there are some unique process controls that need to be put in place to guaranty a well controlled process that does not require cleaning. This paper provides a review of a conformal coating process development for a coating using UV light to provide the cure mechanism.
A UV conformal coating line will usually consist of an In-feed conveyor, Coating applicator, Inspection station, UV Oven and an Out-feed conveyor. The UV oven and the coating applicator are the actual components in the line that require an understanding of the process mechanism and the effect that machine settings have on the process
Conclusions
Several factors have been shown to affect coating thickness and a regression equation with good correlation index has been established to fit this model. UV cure parameters require a complete systems view; it is not just conveyor speed but position within the oven as well as fixturing Finally you must understand your incoming board cleanliness and the amount of "process dirt" that the assembly process reduces the surface energy
Initially Published in the SMTA Proceedings
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