ACCELERATED CURING OF CONFORMAL COATING MATERIALS BY CO2 SPRAY ATOMIZING (01-Jun-1999)

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MOlOROLA Technical Developments

ACCELERATED CURING OF CONFORMAL COATING MATERIALS BY CO2 SPRAY ATOMIZING

  To improve the rate of cure over a typical humidity/CO, cure chamber, CO, atomizing has been introduced upstream at the material spray booth. Atomizing with air is a standard practice in spray applications; the applied material stream is diffused into droplets or "atoms" by the pressurized air. By substituting CO, for air during atomizing, the CO, reacts with the entire conformal coating material layer from the time of application (not just the top layer), accelerating the curing process. The result is a significant reduction in cure time, as well as a robust manufacturing process that allows for varying material thickness without adhesion concerns.

by John Klemmer

  Environmental Compliance Regulations are dri- ving the elimination of materials that emit Volatile Organic Compounds (VOC's) from manufacturing processes. As such Motorola is converting Conformal Coating Materials to a primerless, 100% solids, VOC free silicone material. The need of our organization was to implement a material that would "drop" into the existing manufacturing space without sacrificing quality or throughput.

  The selected conformal coat material cures in a well-circulated chamber, through a reaction with CO2 and relative humidity in the atmosphere. The curing starts at the top layer of material and then permeates down to lower layers. If the material is cured too rapidly, the top...