Conformal coating on PCB

A Conformal coating is a protective chemical coating or polymer film. It is often used to protect the components of a printed circuit board. When applied the film conforms to the to the circuit board topology, hence the name conformal coating.

The coating additionally, protects from harsh operating environments where the components are subject to moisture or chemicals. Not only prevents conformal coating internal damage but but it also forms a barrier on the substrate protecting from air borne contaminants.

In other words, the coating is not only electrically insulating but also anti-corrosive.

Purpose of Conformal coating in Taiwan

fluorescent conformal coating pcb

You can see the Conformal coated parts light up under Ultra Violet light

In modern day Taiwan electronics are part of everyday life. A circuit board is expected to perform in humid weather, hot temperatures or  dry air conditioned spaces, so they are exposed to many different conditions every day. The purpose of conformal coatings is to protect electronic circuits from harsh environments that may contain moisture and or chemical contaminants. The coating prevents the electronic components from corroding and thermal shock.

Humid weather in Taiwan is one of the number one risk for damaging circuit boards. The circuits can become weakly conductive and sudden changes in performance can occur at high humidity. Though the coating is not designed to be a total sealant. Instead it forms a breathable protective layer that will protect against the particular environment requirement of Taiwan. But will also allow any moisture trapped in the circuit board to escape.

 

Advantages of conformal coating for PCB

Conformal coatings are very flexible, easy to apply coating systems which are usually applied in thin layers on PCB’s and other related equipment. The conformal PCB coatings are additionally, easy to remove, repair or replace when needed. They also have several advantages which guarantee improved performance and reduce the risk of system failures. The advantages include for example:

  • Insulation properties which can reduce PBC conductor spacing of over 80%
  • Easy to apply& automate
  • Light weight
  • Highly protective against humid weather conditions, salt and corrosion
  • Easy to inspect (due to fluorescence) The parts light up under Ultra Violet light.
  • Protection from thermal and mechanical shocks

Most conformal coating suppliers are able to create a special formulation, modifying the coating to optimize the properties for the specific application. It is also possible to enhance other characteristics.

dipping conformal coating circuit board

Dipping is a method of applying conformal coating

Conformal coating process

The coating can be applied by brushing or spraying the circuit board. Other methods are dipping or robotic application of specific parts.

Fun Fact: nearly all conformal coatings are fluorescent so it is easy to inspect the coverage with a Ultraviolet lamp.

The coverage has to meet certain standards and can essentially be applied in four ways:

  1. Dipping – Suitable for materials which do not cure under exposure to light, oxygen or moisture
  2. Selective robotic coating – Suitable for all conformal coating types. However, make sure to select the correct dispense head.
  3. Spraying – Hand spray using either a spray booth or aerosol can. Generally suitable for all coatings
  4. Brushing – Requires professional and skilled operators in order to be suitable for production

LED conformal coatings (and displays)

Due to the latest legislation and energy saving attempts in Taiwan more and more incandescent bulbs are replaced with LED’s (Light Emitting Diodes). Especially on the streets of Taipei normal light bulbs have become a thing of the past. A conformal coating is a protective barrier that shields sensitive electronic components against harsh environmental conditions such as moisture, chemicals and debris. The use of a good conformal coating on the drive circuitry and LED lead-frames can mitigate against the corrosive effects of the operating environment. The coating forms an effective barrier to extraneous contaminants, Preserving the circuit’s integrity, as well as mitigating against the potential effects of tin whiskers.

Next to the industrial & residential use, the coatings are also increasing their popularity in consumer and domestic applications which are vulnerable to field failure by environmental factors. Therefor, conformal coatings are used for example in portable devices (tablets, smartphones etc.)  and other consumer electronics from computers to dishwashers.

The cost of protective conformal coating

The price of conformal coatings is usually linked to the volume. Therefore, the larger the volume the lower the price per litre. So the price depends on how many circuit boards must be coated. For an indication contact us. We are happy to help.

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