Definition
Author
- Dr Lee Hitchens, Nexus
A fish eye is a localised de-wetting defect that looks like a fish eye crater on the surface of the conformal coating.
Download our PDF guide Solving conformal coating problems in the application process now.
Examples of conformal coating fish eyes
Examples are shown in the images.
Causes of fish eye defects in conformal coating
Fish eyes are normally caused by a contaminant on the surface prior to application of the conformal coating.
Typically, that contaminant is a substance like a silicon contaminant.
When coating is applied on top of the contaminant, the conformal coating is unable to adhere to the oily surface and a “fish eye” is caused.
How to prevent fish eye problems in conformal coating
- Cleanliness of Surface: Thoroughly clean the surface of the board before coating. Fish eye is a surface preparation defect. If the surface of the circuit bard has been properly cleaned and degreased, fish eye can usually be prevented completely.
Download our PDF guide Solving conformal coating problems in the application process now.
Links
| Blistering | Blushing | Bubble | Contamination |
| Capillary Flow | Corrosion | Cracking | Delamination |
| De-wetting | Discolouration | Fish Eyes | Layering |
| Mealing | Orange Peel | Shadowing | Uneven coating |