In a previous blog “How to Save Time and Money by Measuring the Right Amount of Viscosity,” viscosity was described as critical to the conformal coating process. This post will cover some of the technical details related to coating flow rate and the significant potential for savings of both time and money for PCB manufacturers.
IPC CC-830 revision B is a conformal coating qualification standard mostly used by board fabricators, OEM design engineers, and coatings suppliers.
There are two fundamental uses of this IPC standard:
- Coatings’ performance capabilities
- Quality consistency
In this blog, we will go over some of the specifications along with tests requirements, passing criteria, and quality characteristics.
Have you ever seen your conformal coating separate or de-wet? Have you observed the conformal coating to flake off after cure? The key to your success is understanding the relationship between surface energy (of the substrate) and surface tension (of the conformal coating). There are some simple steps you can take to help ensure you possess a healthy balance of both.
The application of the conformal coating in a uniform and consistent coverage is a key challenge that defines the reliability of the finished product.
A thin coating will provide inadequate protection against corrosion or insulation between conductors. Conversely, if the conformal coating is too thick, it will increase the risk of forming other types of coating defects such as bubbles, insufficient curing, and potential cracking during thermal shock cycles.
Besides the verification of the process parameters such as coating viscosity and the application method is correctly setup, the amount of conformal coating material applied on the printed circuit boards can be measured before curing. For this, wet film conformal coating thickness gauges are used. This method ensures quality control while the coating material is still wet.