Conformal coatings process considerations

Aerobic acrylic conformal coatings have provided major advantages to PCB manufacturers. Currently, solvent-based products dominate conformal coating processes, but safety, EPA, and processing considerations indicate their eventual decline. Although most solvents evaporate in ovens within a few hours, smaller volume manufacturers use systems requiring several days to complete solvent evaporation and/or cure of the resin systems. 

As mentioned earlier, there is a considerable need for a conformal metallic coating with resistivity close to that of aluminum, but with a higher melting point. Of the ones we have been considering, the two lowest resistivity candidates are molybdenum and tungsten. Tungsten has received the most attention since the H2 reduction of WF6 process has been under development for a variety of applications since 1967.15 The extent of current interest can be seen in a recent publication.16... 

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