Five things to know about conformal coating for electronics

As of today, conformal coating applications have not yet achieved a wide diffusion and many of the features that belong to this process are disregarded, misunderstood or even completely ignored by a multitude of companies that could otherwise benefit from them.

In fact, anyone who use industrial electronics inside their products, or inside their processes, could be enjoying a wide array of benefits from conformal coating. Some examples? Here they are:

• A better stability in relation to environmental variables;
• A better preservation in time;
• Enhanced general performances;

Of course, these benefits will only arise if conformal coating is done effectively, with proper know-how and proper equipment.

Alongside any technical detail, which is domain of experts only, there are a few simpler and very useful information that any interested party should have when it comes to conformal coating.

In this article, we'll cover the five most essential pieces of knowledge.

PRODUCT OR PROCESS?

Conformal coating is nearly always associated with the product it gives the name to. But are we sure this is the correct way to intend it? We think it's not. Conformal coating is first and foremost a production process that is conducted when the cooperation of the following elements occure:

• Specific equipment and specific machinery
• Properly trained personnel
• Polymers with precise features These polymers are commonly called Conformal Coating because, as a matter of fact, they represent the substances used to coat the printed circuits in order to make them conformal. What do they need to conform to?Well, they conform to needs of various kinds, sometimes purely technical, sometimes functional and sometimes even regulatory.

PRIMARY SCOPE

The primary scope of conformal coating is the protection of the printed circuits and of the components that are mounted on them. The coating protects from a wide range of elements, among which the most common are:

• Environmental inflitration
• Dust
• Impurities
• Chemical agents
• Humidity
• Extreme Temperatures The protection assured by the coating provides prevention of damages caused by corrosion, moulding, infiltrations and electric deficiency.

APPLICATION METHODS

The most conventional methods of application are the following:

• Dip Coating, which consists of immersing the parts that need to be coated into the substance that will act as protective coat.
• Selective Roboting Coating, which consists of a series of processes completely automated and executed by proper industrial equipment.
• Spray Coating, in which the coating is transformed into a mist that gets sprayed on top of selected areas.
• Brush Coating, which makes use of proper brushes designed to distribute the polymers on surfaces of different size.

Each and every method has its own strengths and the choice of which one is best suited for a specific product is very case sensitive. In CTA Electronics, we can count on a proper production department entirely equipped for conformal coating, which allows us to execute the selective roboting coating as well as any other kind of application.

SUBSTANCES AND MATERIALS

The primary reason why there are many different kinds of conformal coating resides in the fact that every polymer has its own defining feature. Simplifying, we can say there are mainly four product families:

• Acrylic polymers, particularly resistant to environmental agents but not so performing in terms od chemical resistance;
• Polyurethans, that combine an excellent chemical resistance to a remarkable protection from external agressions and variuos agents like humidity and extreme temperatures;
• Silicon polymers, extremely hard to remove and re-work, they guarantee optimal endurance;
• UV cure polymers, they activate after a photochemical reaction arising from UV light and they assure infallible resistance to abrasion and to chemical agents.

IMPROPER USES

Improper tools or unexperienced resources may cause productive damages that are very likely to discard the benefits of the coating application. Elements like:

• Viscosity
• Density/Surface Ratio
• Dosage
• Selection of Application Areas

Must be carefully measured upon the very specifical needs of each and every production batch, and the entire process must be managed skillfully and proactively.

CONCLUSIONS

Conformal Coating is, by all means, a very interesting application for the industrial electronic industry and is a complementary process that is able to add value to the production of electronic boards, circuits and complete products. However, in order to be successful and valuable, this process must be handled upon a firm know-how and should be executed only by companies with a solid base in terms of knowledge, experience and possession of professional equipment.