Selective Conformal Coating Enhance the Reliability of PCBs
Printed circuit boards (PCBs) are used in a wide range of applications, from industrial and green energy to aerospace and military. In order to function and remain reliable they must be able to withstand a variety of environmental conditions, from humidity to harsh or corrosive environments. Conformal coating enhances the reliability of PCBs by protecting them from the elements. However, not all conformal coating is equal and the way in which it is applied can make a big difference to its performance. This is why selective conformal coating is important for manufacturers.
The first step in the process of applying a conformal coating is to select the correct material. There are a variety of options, including acrylic, silicone, urethane and parylene. Each offers different properties, from humidity and chemical resistance to temperature endurance and cost. Choosing the right coating isn’t a simple task and requires technical knowledge and experience to ensure that it will meet all of the required criteria.
Once the appropriate coating has been selected, the next step is to apply it to the rigid-flex pcb. There are a number of ways this can be done, including spraying, brushing and dipping. The method selected will depend on the requirements of the production line, and factors such as equipment availability, cost and quality requirements. For example, for mission critical electronics it is essential that the coating can be accurately and repeatedly applied to a high standard, and this may require more advanced and automated systems.
How Does Selective Conformal Coating Enhance the Reliability of PCBs?
One of the most common problems associated with conformal coating is de-wetting, which can occur when the coating fails to adhere properly to the substrate. This is often caused by contaminants on the surface of the board, such as greases or oils, and can be prevented by ensuring that the board is thoroughly cleaned and free from debris before coating. Another problem encountered with conformal coating is orange peel, which occurs when the dried coating has a texture resembling that of the skin of an orange [1]. This can be caused by excess or insufficient application and can also be avoided by making sure that the coating is applied and cured evenly.
Using a selective conformal coating system can help to overcome both of these issues. By programming the precise areas of the board to be coated, the system ensures that the right amount of coating is used and that it is deposited where it is needed. This can also reduce costs by avoiding wasted coating on un-needed areas.
Using a selective conformal coating system also helps to eliminate other problems that can occur with manual spraying, such as capillary effects that transfer material to unwanted areas of the board. These can be caused by insufficient coating coverage, and by the fact that a mask may not have been used to protect components such as connectors. By eliminating these problems, a selective conformal coating system can provide a more accurate and consistent result than manual application methods.