For many years PCB coating has been considered an excellent solution for protecting printed circuit boards (PCBs) from various environmental impacts. Radiation, temperature changes, humidity, and other natural causes often cause those impacts.

PCB protective coating enables the circuit board to withstand harsh environments and operate for many years. We use PCBs in industrial, medical, and military applications. Those applications will expose the PCBs and their board components to high temperature and humidity environments.

In such cases, circuit board protective coating could be the perfect solution. In this article, we will cover circuit board coating, different coatings, and how it protects PCBs.

I. PCB coating brief introduction

PCB protective coating refers to the finishing material applied on top of the circuit board at the end of the PCB production. Circuit board coating consists of multiple combinations of chemicals. However, all layers serve the same purpose – to protect the PCB from damage.

PCB manufacturers often apply PCB paint by spraying the circuit board using a designated PCB coating spray. Customers often choose to apply the coating by the end of the pcba process, which will protect components and electronic parts. 

The PCBA protective coating sometimes has other purposes. Waterproofing the board or ensuring the PCB design integrity is often a good reason to coat your PCB.

The widespread use of PCB coating prevents corrosion due to environmental impact. By applying the PCB coat spray, the circuit board can operate for many years uninterruptedly.

PCB paint can strongly isolate the PCB and PCBA from environmental effects. Insulating from external forces such as temperature, radiation, and vibration will improve the product’s lifespan and quality.

II. Resin PCB coating advantages vs. disadvantages

The resin coating, often called solvent acrylic acid, is commonly used on PCBs. There are multiple considerations to do when it comes to choosing whether you should use resin coating. Typically, the advantages overcome the disadvantages of this particular PCB spray paint and its applications. However, some disadvantages require attention, especially for industrial applications exposed to high temperatures and humidity.

Resin coating advantages

Some of the Resin coating advantages include the following:

• 1. Easy to apply – a simple and available option offered by many PCB and PCBA manufacturers.
• 2. Unreactive material – PCB paint doesn’t react to oxygen. The color doesn’t require a particular laboratory condition.
• 3. Extraordinary protection abilities – can withstand high humidity and temperatures.
• 4. Enables easy rework during the SMT process
• 5. It doesn’t cost much and provides increased reliability over time.

Resin coating disadvantages

Although not many, we should mention the disadvantages of using such coating as well:

• 1. Need to apply in the right amount – Thin layer will result in poor PCB performance.
• 2. Resin requires a thick layer for high-humidity industrial applications, which might increase the production cost.

III. Epoxy resin PCB coating

Manufacturers apply Epoxy to enhance PCB durability. Although more expensive than Resin coating, Epoxy can provide higher durability for industrial uses. Such applications include air conditioning, fog machines, industrial fridges, and more.

Epoxy resin advantages

Epoxy raisin has insulating properties. The epoxy resin advantages include:

• 1. High resistance to humidity, foggy environments, and chemicals.
• 2. Ability to operate in extremely high temperatures, up to 150°C.
• 3. Resistant to scratches and vibration damages.

Epoxy resin disadvantages

• 1. Reworking will cause damage if done improperly, and manufacturers will prefer to rework the PCB manually. Reworking manually will prevent stress, temperature changes, and vibrations which might permanently damage the circuit board.
• 2. Epoxy resin should always be used in high-temperature environments. Low temperatures might give unexpected results and quiet performance.

IV. Organic silicon PCB coating

The organic PCB paint coating is suitable for components that can resist high temperatures and frequencies. High-frequency printed circuit boards are optimal for such layers. The organic coating makes a perfect choice for industrial, medical, and military applications. Manufacturers consider Organic PCB coating to be quite expensive for consumers to use.

Organic silicon coating Advantages

Some of the Organic silicon PCB coating advantages include:

• 1. It can be used in most environments, allowing high flexibility for many applications.
• 2. It can operate in extremely high and low temperatures, making it suitable for worldwide use in any condition.
• 3. Easy to be repaired and rework.
• 4. It contains insulation properties that enable higher durability and protection from unwanted environmental impacts.

Organic silicon coating Disadvantages

The Organic silicon coating disadvantages include vulnerability to mechanical changes such as vibrations. The coating surface is easily scratched and damaged by touching other surfaces. If the PCB is in the open air, it won’t be a good idea to use Organic silicon. However, it could work for closed enclosures in indoor applications.

V. PCB coating using polyurethane

Polyurethane is a synthetic material used to coat and protect different types of surfaces. Polyurethane applies to many applications, both for industrial and consumer goods. The coating is often used for applications without strict application requirements.

Polyurethane Advantages

The advantages of polyurethane coating might not seem like much, but they can do wonders once applied to the right project. The coating abilities include the following:

• 1. Outstanding resistance to both alkaline and acidic chemicals.
• 2. Ability to withstand high humidity environments.

Polyurethane Disadvantages

The curing process requires strict control and treatment. Too much curing will affect the PCB color and turn it yellow. High curing temperature could affect the PCB in unexpected ways, reading the quality and performance of the final product.

VI. How to choose PCB coating type

This article covered many types of PCB coatings, both for industrial and consumer goods. The PCB paint should be selected based on application-specific purposes. Some coating will require high-temperature resistance while others don’t.

Different applications will have additional requirements for circuit board coating. When choosing a suitable PCB coating, always consider the final application whether it’s industrial, consumer-based, or medical and military-grade.

If you wonder what coating is best for your PCB, we at PCBasic can help you to choose. PCBasic has dozen of engineers with years of expertise available one click away. As a trusted pcb and pcba assembly supplier manufacturer, we can recommend you the best PCB coating for your application.