Conformal Coating Enhances the Reliability of PCBs
Printed circuit boards (PCBs) are exposed to harsh environments that can damage them and cause failure. These conditions include humidity, moisture, corrosion, salt spray, tin whisker mitigation and other issues. PCBs can be coated to protect them from these harsh environments, allowing them to remain functional and reliable for a longer period of time. However, ensuring that the right conformal coating is applied requires careful coordination of board design and application with the correct cleaning protocol.
Conformal coatings are thin polymeric materials that seal and insulate circuit boards from environmental contaminants. They also provide extra dielectric insulation, allowing components to be placed closer together, and can prevent solder joints from melting or breaking. In addition, they can help protect circuit boards from thermal stress and mechanical abuse during handling.
In order to ensure that the coating is effective, it must be inspected and tested under a range of conditions. These tests can include electrical testing, humidity testing and flexibility testing. Humidity testing can be particularly important, as moisture in the air can react with metal components and connections to cause corrosion. Flexibility testing can ensure that the conformal coating is able to withstand various types of physical stresses and movements.
There are a number of different ways that conformal coating can be applied to rigid-flex pcb. Manual spraying, which can be done using aerosol cans or handheld spray guns, is the fastest approach. However, it can be labor intensive and may require the use of masked areas in order to prevent coating unintended surfaces. In contrast, automated spraying systems move the PCB on a conveyor under a reciprocating spray head and deposit the coating precisely where specified by the system. This can reduce the need for masking and offers a more consistent and repeatable process.
How Selective Conformal Coating Enhances the Reliability of PCBs
Another method is to brush the conformal coating on. This is slower, but can be a good option for low volume production. It can also be used for touch-up applications or rework on previously coated PCBs. However, it can result in variations of the coating application and may not be suitable for masked areas or high-reliability applications.
Selective conformal coating systems offer the best of both worlds by combining the speed and consistency of automated processes with the flexibility and precision of manual techniques. They can be easily adapted to existing application equipment and can optimize the amount of coating that is deposited while still offering excellent control over dispensing starts and stops.
They also allow you to avoid over-spray that could interfere with component encapsulation or tin whisker mitigation, while providing a more controlled and repeatable process. This means that you can avoid wasting expensive coating and still achieve the required levels of protection for your assemblies. If you are considering selective conformal coating to enhance the reliability of your PCBs, contact us today for more information about our range of products and services. We are here to help you choose the best option for your specific requirements.
In addition to solder paste application, stencils are also used in the application of other assembly materials, such as adhesives or conformal coatings. These materials may be required to bond components to the PCBs or provide protection against environmental factors. Like with solder paste, stencils ensure precise application of these materials, preventing excess or uneven coating that could affect the performance and longevity of the PCB assembly.
