How to Control Viscosity with Dip Coating Equipment

Dip coating is an efficient ways to apply conformal coating. While it can be done manually, dip coating is usually done with automatic equipment to greatly increase the amount of consistency within the process as well as lower labor costs. Dwell time is a vital factor to control the thickness of the coating as well as controlling material usage. The optimum dwell time for a particular board design should be determined by varying the withdrawal rate with viscosity of the conformal coating material.

There are two methods for controlling viscosity with conformal coating materials and dip coating applications:

• Flow cup control is a manual process. A cup of known size with a hole in the center is filled with the conformal coating and the time for the material to run out is related to viscosity. This is reasonably accurate and normally is suitable for most applications.
• Inline automatic viscosity control is where the solvent evaporation and material is controlled by a viscometer-controlled system. This is extremely accurate and removes all of the manual processes involved in testing with a flow cup.

Whether using an automated, inline viscosity control system or manual flow control cups, controlling viscosity in dip coating equipment is vital to a successful coating project.