The measurement of the conformal coating thickness on a printed circuit board (PCB) to ensure internal and international standards are met is now a standard process in production.
There are several methods for measurement of conformal coating thickness including dry and wet film processing. However, the most important factor is how thick should the coating be?
First, you can reference both internal and international standards like IPC A 610 for conformal coating application. They can help a lot.
These standards will help guide you in the coating thickness required for a particular coating materials since the coating thickness suggested will be dependent on the resin of the conformal coating.
For example, an acrylic or polyurethane based conformal coating has a different coating thickness requirement to silicone-based materials.
Below are the suggested conformal coating thicknesses from the IPC A 610 standard:
- Acrylic 30-130 μm
- Urethane 30-130 μm
- Epoxy 30-130 μm
- Silicone 50-210 μm
- Parylene 10-50 μm
Note, that this is the average thickness across the circuit board. It is almost impossible to achieve a homogeneous coating thickness with the liquid conformal coatings due to surface tension issues during drying.
Using this information you can now move forward and look at the application of the conformal coating.
Need to find out more?
For further information on process control and conformal coating thickness then contact us directly.