Datasheet

Page 4
Spraying - Aerosol
When applying AFA care must be taken to ensure the can is not shaken before use. Shaking the can will
introduce excessive air bubbles and will give a poor coating finish. The can should be held at 45°, and 200mm
from the substrate to be coated. The valve should then be depressed when the can is pointing slightly off target
and moved at about 100 mm/s across the target. To ensure the best coating results are achieved try to use a
smooth sweeping motion with small overlap for successive rows.
To ensure penetration of the coating beneath the components and in confined spaces, spray the assembly from
all directions to give an even coating. After spraying, the boards should be placed in an air-circulating drying
cabinet and left to dry.
Dip Coating
AFA has been formulated to a suitable viscosity for dip coating (175 ± 25 mPa s @ 25°C). The coating material
should be checked periodically using a viscometer or "flow cup" and FTH added as required to replace the
solvent lost by evaporation and maintain the viscosity.
The board assemblies should be immersed in the dipping tank in the vertical position, or at an angle as close to
the vertical as possible. Connectors should not be immersed in the liquid unless they are very carefully masked.
Electrolube Peelable Coating Masks (PCM/PCS) are ideal for this application. Leave submerged for
approximately 10 seconds until the air bubbles have dispersed. The board or boards should then be withdrawn
slowly (1 to 2mm/s) so that an even film covers the surface. After withdrawing, the boards should be left to
drain over the tank or drip tray until the majority of residual coating has left the surface. After the draining
operation is complete, the boards should be placed in an air-circulating drying cabinet and left to dry.
Brushing
Ensure that the coating material has been agitated thoroughly and has been allowed to settle for at least 2
hours at ambient temperature. When the brushing operation is complete the boards should be placed in an air-
circulating drying cabinet and left to dry.
Inspection
AFA contains a UV trace, which allows inspection of the PCB after coating to ensure complete and even
coverage; the stronger the reflected UV light, the thicker the coating layer is. UV light in the region of 375nm
should be used for inspection.
Revision 9: April 2017