Comparison of Potting and Conformal Coating

Printed Circuit Board (PCB) is a layout design of the schematic that provides electrical connections for the components on the board. With the advancement of electronic technology, even a single electronic device nowadays has a PCB board. The PCB is a wire coating for conductors on insulation. The PCB design process involves several steps, including:

During the design process of a PCB, protecting the assembled PCBA board is just as important as ensuring signal integrity, power distribution, and thermal management. Electronic equipment that utilizes these printed circuits is prone to damage from various sources such as electrical surges, thermal stress, moisture, and physical influence. To safeguard against these threats, common protective measures include potting and conformal coating. To assist in making the appropriate choice for your project’s protective measures, FS Technology offers our own perspective:

Potting PCB Board

PCB Potting, also known as encapsulation, refers to the addition of a special layer of material around an electronic component to make it a single unit, designed to protect the printed circuit board from environmental factors and improve its mechanical strength. This process typically involves using a two-part epoxy or polyurethane resin that is poured or injected into a mold or enclosure around the PCB and then cured to form a solid or semi-solid protective layer.

Commonly used potting materials

The selection of a potting material for PCBA depends on specific application requirements. Factors such as temperature, chemical resistance, and mechanical properties are all important considerations. Here are some commonly used potting materials:

Epoxy Resins: They are the most commonly used potting materials for PCBA due to their excellent adhesion, chemical resistance, and thermal stability. They are suitable for electronic applications used in industrial settings, such as power inverters, motor drivers, and controllers.
Acrylic Resin: These are used in potting applications that require high clarity and good electrical insulation properties. They are also resistant to UV radiation and offer good adhesion to a variety of substrates.
Polyamide: This potting material is suitable for high-temperature applications and offers excellent chemical resistance. It can withstand exposure to harsh environments.
Silicone Rubber: It is a soft and flexible potting material that can provide good shock absorption and vibration dampening. It is also resistant to heat, chemicals, and moisture.

Characteristics of potting

Protection: Potting is an effective method for protecting PCB assemblies against mechanical, thermal, and chemical stress.
Environmental Resistance: Potting materials are highly resistant to environmental factors like moisture, dust, and UV radiation.
Insulation: Potting materials act as electrical insulators, protecting PCBs against short circuits and other electrical faults.
Shock Absorption: A buffer area is created between the PCB and vibration sources, which can absorb vibration and reduce the impact of mechanical stress and impacts on the board.
Compatibility: Potting materials are compatible with the materials used in PCB assembly, including components and substrates.
Application: Potting can be applied flexibly using a manual or automatic dispensing system depending on production volume.
Increased Weight and Size: Potting adds a large amount of material to the PCB assembly, which can be detrimental to applications where weight and size are critical.
High Cost: Potting requires additional materials and processing steps, increasing the overall manufacturing cost of PCBA.
Chemical Compatibility: Certain types of potting materials may not be compatible with sensitive electronic components such as sensors or MEMS devices.
Potential Impact on Thermal Performance: Potting materials act as thermal insulators and can negatively affect the thermal performance of the PCB. This is especially true in high-power applications that generate a lot of heat.
RF Devices: Potting materials can affect the performance of antennas for RF devices by attenuating or reflecting RF signals, which can degrade the antenna’s performance. If the potting is too thick or dense, it can absorb or reflect RF signals, reducing the efficiency and effective range of the antenna. On the other hand, if the potting is too thin or not dense enough, it may not provide adequate protection for the electronic components, leading to reliability issues.

Conformal coating

Conformal coating is another commonly used effective protective measure. Unlike potting, conformal coating is a thin layer of polymer material that conforms to the contours of PCBs and components. It is applied to the board to prevent moisture, dust, and chemicals from affecting the components. This is an essential process that helps ensure the longevity and reliability of electronic equipment, especially in harsh and challenging environments. FS Technology can provide free conformal coating services for PCBA prototyping.

Conformal Coating Material

There are several types of conformal coatings available in the market, including acrylics, urethanes, silicones, and epoxy, each with its unique properties, advantages, and disadvantages.

Acrylic coatings are the most popular and cost-effective option as they provide excellent protection against moisture and humidity.
Urethane coatings are known for their superior chemical resistance and adhesion, making them ideal for applications that require exposure to harsh chemicals.
Silicones are highly flexible and provide excellent thermal stability, making them ideal for use in high-temperature environments.
Epoxy coatings are the most durable and provide exceptional protection against impact and abrasion.

How to apply the conformal coating?

The application of conformal coatings involves several steps, including cleaning, masking, spraying, and curing. Firstly, the surface of the device is cleaned to remove any contaminants that may impact the adhesion of the coating. Then, masking is performed to cover the areas that do not require coating to prevent overspray. Subsequently, the coating is applied using a spray gun, brush, or dip process, depending on the coating type and application requirements. Finally, curing is performed by heating the coated device to a specific temperature to promote cross-linking and ensure proper adherence to the surface.

Conformal coating offers several advantages, including preventing failures due to moisture and contaminants that can cause corrosion, short circuits, and electrical leakage. The coating creates a barrier between the device and the environment, keeping the components dry and protected. Additionally, the coating reduces maintenance and repair costs by extending the device’s lifespan, decreasing the need for repairs or replacements, and ultimately reducing costs.

In conclusion, conformal coating is a crucial process that protects electronic devices from environmental damage, extends their lifespan, reduces maintenance and repair costs, and improves their reliability and performance. With the wide range of conformal coatings available, it is essential to select the appropriate coating type to suit the application requirements and provide the best possible protection.

Conformal Coating vs Potting

Aspect	Potting	Conformal Coating
Definition	Encapsulating an PCBA or component in a solid or semi-solid material.	Coating an PCBA or component with a thin layer of material.
Materials	Epoxy, Silicone, Polyurethane	Acrylic, Silicone, Urethane
Thickness	Thick, typically >1 mm	Thin, typically 25-250 µm
Application Method	Dispensed or poured onto PCBA or component	Sprayed, brushed, or dipped onto PCBA or component
Coverage	Covers entire component or PCBA	Covers only exposed surfaces of component or PCBA
Purpose	Provides mechanical strength and protection against impact, vibration, and moisture	Provides protection against moisture, dust, chemicals, and temperature changes
Accessibility	Difficult to repair or replace component or assembly once potted	Easier to repair or replace component or assembly
Cost	Higher cost due to material and labor involved	Lower cost due to thinner material and simpler application method
Applications	Harsh environments, high-vibration applications, or components that need to be hermetically sealed	Moderate environments or components that require protection against moisture and dust, but still require accessibility for repair or replacement

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