Generally, bubbles, pinholes, and foam are all one and the same defects of a conformal coating process.
Bubbles are trapped pockets of air within the coating while pinholes are burst bubbles that reach the surface of the PCB. Foam refers to extreme bubbling.
There are several factors that contribute to these defects including
- Premature drying
- Application of too-thick coating
- Air entrapment
- Wrong viscosity
- Too much pressure
However, some ways to prevent these from occurring include
- Applying the correct film thickness
- Proper drying
- Changing the application technique
- Turning off the pressure
- Blending the coating
- Adjusting the pressure
To find out more click Conformal Coating Defects: Pinholes, Bubbles and Foam
Who is Nexus?
Nexus brings together the accumulated knowledge of a group of conformal coating and electronics material dispensing consultants who provide a unique service, focused on helping electronics manufacturing clients improve their conformal coating and electronics materials processes.
Nexus operate across North America, Europe and Asia and can provide a unique perspective to the rapidly growing conformal coating and electronics materials industry. Expertise is held in liquid and parylene coating, capital equipment sales and specifications and material, equipment and process specification, troubleshooting and training.