After the actual production process of a printed circuit board to be assembled, reliable protection of the electronic assembly against mechanical and environmental influences by means of a protective coating is becoming increasingly important. The aim of such a coating is to reduce corrosion and its consequential damage and the resulting improvement in the service life, functional safety and reliability of the end products.
Protection against moisture, condensation and chemical contamination prevents short circuits and leakage currents, as well as voltage flashovers and discharges. Closer conductor routing and higher performance can be realized in the module design. Whisker and dendrite growth and electromigration are prevented and the fatigue of soldered connections is reduced.
In conformal coating, opaque or transparent lacquers are applied to the PCBs for individual contours or over the entire surface. A thin application of flexible layers with adhesive-free surfaces of mostly transparent polymer materials is applied, which is uniform in color and structure. The aim is to achieve a layer thickness that is as uniform as possible and not too thick or too thin. The recommended layer thicknesses vary depending on the material and range from approx. 20 to 150 µm. Despite thin layer thicknesses, good mechanical protection against vibration and shock loads is also provided. The PCBs are transported into the fully automated coating system using product carriers, coated and dried. The coated surface is then subjected to a quality check. In our application, we use systems from Nordson ASYMTEK and REHM.
