Do you know the purpose of conformal coating?

Long term use of electronic components are easy to wear, because positioning is a consumable. However, consumers expect that electronic products can be used for a long time to save some expenses. Therefore, the manufacturer has developed methods to protect its components from damage and maintain its long-term function. One of these methods is called conformal coating. This process can protect PCB from mechanical and chemical damage, and prolong service life and reliability by various methods.

1. What is Conformal coating ？

Conformal coating It is a special polymer film that can protect components and PCB boards from mechanical or chemical damage. It is essential to protect aerospace components from extreme conditions and was originally developed for mission critical applications. In the current modern digital age, conformal coating technology has become common in many applications, including coatings used by the general public such as mobile devices.

Conformal coating It is usually in the form of resin mixed with water or various solvents and can be applied by various methods. Pure resin based conformal coatings are translucent, but coatings combined with other substances (such as epoxy) are waterproof and opaque. Conformal coatings commonly used for electronic components are semi permeable. Electronic products with conformal coating can easily repair the coating without any trouble.

Resin based Conformal coating Most are made of acrylic, silicone or carbamate. Each resin has a specific strength in harsh environments. For example, acrylic resin has high dielectric strength and silicone grease is resistant to salt spray. Polyurethane has wear resistance, moisture resistance and chemical resistance. Depending on their strength, each conformal type must be removed by a specific technique. Acrylic coatings can be removed more easily by using solvents, but silicone and polyurethane coatings need special solvents, stirring in ultrasonic bath and long soaking time.

Another coating is called non conformal coating. The manufacturing method and method of these coatings Conformal coating Similar, but its adhesion is not as good as the surface characteristics of electronic components, so it is named. It is thicker than conformal coating and difficult to maintain.

2. The conformal coating is improved by mask.

When placing conformal coatings on components, it is best to keep some areas uncoated. These areas include connectors, holes, LEDs, and certain types of integrated circuits. Preventing these areas from being covered is related to a process called masking.

There are many kinds of covering technology, including covering, adhesive tape, liquid and gel. No specific technology is always applicable to a specific mask scene. Designers must consider many factors before masking. The shape, geometry and function of occlusion area and the protection level provided by occlusion are the main factors affecting the designer's decision to use occlusion. Designers must also consider the expected life of the mask and how difficult it is to remove the mask if necessary.

Some mask technologies permanently prevent Conformal coating Some are temporary. Permanent liquids and gels are common, but some new technologies have opened up more possibilities for temporary masking. UV curable temporary mask solution was recently added. It is easy to apply and remove, and does not need physical media such as shielding layer and tape. In addition, the geometry of the plate and the solid covering material are not subject to the same restrictions. Despite these advantages, these temporary liquids still need skilled application and removal technology, and some automation can be realized, but skilled technicians must guide the application tool, which is not easy.