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12 Guides To Help You Choose The Right PCB Conformal Coating

With the globe continuing to witness the miniaturization of circuitry and electronics, the conformal coating PCB seems to have skyrocketed than never before. To shield a PCB from elements such as moisture, extreme temperatures, and dust, manufacturers apply conformal coatings. Choosing the best type of surface to use is vital.


However, weeding through plenty of information found online is a daunting exercise. But that is not the case anymore in this time and age. In this post, we are going to provide 12 guides on how to go about choosing the ideal conformal coating for your PCB.

What is Conformal Coating?

Conformal coating is a protective layer of polymeric film that manufacturers apply to printed circuit boards (PCBs). Although the conformal coating is typically breathable and thin, it provides ample protection against moisture and other contaminants. It gets its name from the fact that it conforms to both the geometrical irregularities of the PCB’s structure (including its components) as well as the environmental irregularities it may be placed in. 

With the globe continuing to witness the miniaturization of circuitry and electronics, the conformal coating PCB seems to have skyrocketed than ever before. To shield a PCB from elements such as moisture, extreme temperatures, and dust, manufacturers apply conformal coatings. Choosing the best type of surface to use is vital.

However, weeding through plenty of information found online is a daunting exercise. But that is not the case anymore in this time and age. In this post, we are going to provide 12 guides on how to go about choosing the ideal conformal coating for your PCB.

Functions of Conformal Coating of a PCB

shielding electronic components from corrosion and environmental elements, the surface also plays other essential roles. 

Other roles include acting as an insulative material for a printed circuit board and minimizing environmental stress when assembling a printed circuit board. Conformal coatings are also crucial since they assist in eliminating the need for sophisticated and complex enclosures. 

Conformal coatings also ensure a printed circuit board’s longevity by protecting it from fungus, heat, humidity, and airborne contaminants such as dust and dirt. 

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Classification and Properties

There are several options for conformal coating technologies, with the best option depending on the required protection. Ease of rework and the method of application are also essential factors to be considered. The following are some of the typical classifications of conformal coating:

• Acrylic acid resin – they are excellent at providing general protection and moderate elasticity. It is also recognized based on its moderate moisture resistance and dielectric strength. 

• Epoxy resin –  apart from creating hard coatings, they come in two parts. They offer excellent humidity resistance and consist of high chemical and abrasion resistance. 

• Organic silicone – this one provides average fungal and moisture resistance. It highly excels at high-temperature ranges and is good at high-vibration tools.

• Polyurethane – this coating is excellent when it comes to chemical and moisture resistance. Additionally, PolyurethanePolyurethane is abrasion and solvent-resistant.

• Parylene – this unique type of surface applied through a cured offers high vapor-phase deposition. Apart from its excellent dielectric strength, this type of cover is suitable for working in applications where temperatures are high.  

• UV curing coating – UV cured coatings are known for being difficult to repair or rework while coatings that get cured offer fast production throughputs.

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Conformal coating choosing principles

To ensure that your PCBs have the right coat of the conformal coating material, you may have to go through a series of selection principles. It will ensure that you find the best of the best material. Here are the selection principles that you need to watch out for:

Single Piece Is Easier To Operate

When selecting conformal coatings, you need to go for unique part components first. Single-component conformal coatings mean that the surface does not require mixing conformal ingredients before application. Single-component layers are highly preferable because they provide excellent chemical and humidity resistance.

Single-coating components are also among the best coatings to use because they are easy to apply and enjoy a long pot life. The only major drawback is that they need some long curing to achieve optimum care.  

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Material Cure Mechanism

The cure mechanism is not a primary criterion when choosing the type of surface to use. In the long run, though, it directly impacts the nature of the method of application that will be workable.

There are types of cure mechanisms that are known to be relatively dependable. Simultaneously, some are complicated and leave room for several application errors, mainly when used in uncontrolled environments. Some of the most basic cure mechanisms include:

• UV Cure—Here, coatings are cured using ultraviolet light and offer quick production throughputs. Layers cured through UV are a bit challenging to rework and repair.  

• Heat Cure –this type of curing is used as part of a secondary UV Cure mechanism, evaporate cure, or moisture cure. Heat Cure is ideal if one cure mechanism cannot meet the required cure properties.

• Moisture Cure – this is a curing used with an evaporative cure.  

• Evaporative Cure Mechanism—Here, the liquid carrier first evaporates, leaving behind a coating. While somewhat simple in theory, PCBs may have to be dipped at least two times to ensure a buildup of enough layer on the components’ edges.

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Long Shelf Time

Shelf life or product shelf life is the maximum recommended time for a product to last on the shelf. During this time, the defined quality remains, as stated under the stated conditions of display, storage, and distribution. You do not want to purchase products that only last a few days or weeks before going bad.

Among other nuisances that customers often complain about, little shelf life makes it the list of significant problems, especially for customers who prefer goods that will last long. The same is true when it comes to selecting conformal coatings. Some coatings do not come with the promise of long shelf life, hence the need to avoid them if possible. Silicone Conformal Coating 433B is an ideal product, not only for its faster cure time but also for longer shelf life.  

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Wide Range Of Operating Temperature Range

As you may be aware, plenty of PCB designers are lately squeezing more and more performance out of PCB. Power densities seem to be on the rise, and so are high temperatures with the ability to wreak havoc on dielectrics and conductors. Some PCBs tend to function in high-temperate environments, such as those meant for military-grade applications.

When choosing a conformal coating to use on your PCB, you’ll be in a better position going for materials that can withstand a wide range of operating temperature ranges. The surface should do so without impacting the functionality of the board. For instance, silicone resin is one of the best materials that can offer protection in a wide temperature range.

a PCB coating that could not maintain drastic thermal changes.jpg

Engineering or Performance Characteristics

When shopping for a conformal coating to use on your PCBs, its engineering or performance characteristics matter the most. What are its chemical properties? Have you checked whether the surface is resistant to instances of dust and humidity? You do not want to use a layer whose performance on your PCB would be below par.

Before selecting the type of coating to use, make sure that it cannot cause or bring about stress on components, especially during thermal extremes. The surface must have the ability to withstand thermal hot-spots that are produced by components.

a PCB with fine coating and outstanding performance on thermal stress.jpg

Ability to Protect The Board From Extremely High/Low Temperatures And Mechanical Impact

Individual PCBs find substantial use in high-temperate environments such as equipment used in the military. Still, individual PCBs regularly get exposed to situations where the mechanical effect is enormous. You have to ensure that components on the printed circuit board are shielded both from high/low temperatures in addition to high mechanical effects. To achieve this, you’ll have to shop for a conformal coating with such characteristics.

At high or low temperatures, some types of conformal coatings will fail, thereby affecting the functionality of your entire board. The cured coating needs to be abrasion-resistant to withstand constant handling, especially during manufacturing. 

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The Conformal Coating Should Get Cured at High Speeds Without By-Products Generation

Curing conformal coatings happen immediately after the process of dispense or coating spray is done. The surface is regarded as fully cured when the conformal coating applied on the PCB board is tack-free to get handled. 

At times, curing can be accomplished at average room temperature, even though it takes some significant time to dry. Most engineers desire to produce PCBs at high rates for them to realize substantial profit margins. The conformal coating selected must be able to get cured at high-speeds without generating by-products to achieve these profits.

a close-up shot of a PCB with remarkable conformal coatings.jpg

Low Toxicity And Low Cost

As a PCB manufacturer, there’s nothing more dangerous than dealing with toxic materials that may negatively impact your health. Unfortunately, this scenario is common when manufacturing PCBs. Many PCB firms use highly toxic compounds, some of which were banned many years ago. Much worse, some of them use high-cost materials and pass the manufacturing cost to the end customer.

A good conformal coating material, apart from ensuring that it is low-cost and affordable, should be made of non-toxic materials.

a low toxic and highly efficient curing on a PCB.jpg


The conformal coating that you choose to use must be easily repairable or re-workable. Repairability is an aspect that ensures that the solder touches up takes place as desired during component placement. For excellent results, the materials you choose to use for patching must be the same as those used in the initial assembly coating. 

a circuit board that has easy to repair coating.jpg

Verification Method and Technique

Lastly, when choosing the best conformal coating for your PCBs, you need to ensure that you subject them to verification methods and techniques. Fundamental verification and technique methods include inspection, demonstration, test, and analysis.

Verification will ensure that you get to avoid errors before you begin mass production of your PCBs. You need to ensure that you inspect the conformal coating you use and demonstrate if it can work, test, and analyze using calculations and test models.

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How Do You Apply Conformal Coating?

There are a variety of ways to apply conformal coating. The five most common are:

  • Hand-coating using a brush: Many consider this the least effective technique as it may lead to over-application of the conformal coating. 
  • Manual coating via an aerosol spray can: Ideal for small productions and board prototyping. You should perform it in a specialized spray booth for the best results.
  • Using an atomized spray gun is similar to using an aerosol spray can. However, it is potentially quicker and more effective.   
  • Automated dip coating: This method involves a machine slowly dipping the board into the conformal coating. It must be performed as slowly as possible as removing the board too quickly from the solvent increases the risk of streaks. This is because the solvent dries as soon as it meets the air. Dip coating also requires manufacturers to mask parts of the board, such as contacts. Thus, it can be tedious and time-consuming. 
  • Selective coating machine: Similar to automated dip coating, this is a machine-based technique. However, it’s far more efficient. In fact, it’s the most effective way of applying conformal coating. Although, it is also the most expensive method and it requires an experienced and skilled operator.  First, the operator programs the selective coating machine, configuring the amount/thickness of coating required as well as the areas to coat. The operator then runs the PCB through the machine, where a set of nozzles and valves applies the conformal coating. 
Flexible Robotic Conformal Coating Dispensing System

Flexible Robotic Conformal Coating Dispensing System

Regardless of which method you use, you must ensure that the PCB is clean and free from contaminants or debris. Additionally, the work area must also be clean, well-ventilated and contaminant-free. 

How Do You Remove Conformal Coating?

There are several reasons for wanting to remove conformal coating from a PCB. For instance, you might want to repair it, remove and replace components or trace reworking. Regardless of the reason, there are a few ways you can remove conformal coating. Depending on the type and thickness of the conformal coating, you can: 

  • Peel: This method works best for conformal coatings that consist of silicone or flexible material. The thickness of the coating is also important in determining how effectively you can utilize this technique. This method involves manually peeling the conformal coating from the PCB.
  • Using Solvents: This method involves using solvent to dissolve the conformal coating from the PCB. If you do decide to use a solvent, you must ensure that it is compatible with the conformal coating. Additionally, you should select a solvent that will not be corrosive or damaging to the components of the PCB. Regardless of how compatible the solvent is, some coatings require more time to remove than others. For instance, urethane and silicone-based coatings need to be soaked, while acrylic-based coatings can be removed with a wipe.
  • Grinding/Scraping: This technique involves abrasively rubbing the circuit. It’s most suited to harder conformal coatings like polyurethane and epoxy. You should only attempt grinding or scraping when all other methods have proved fruitless.
  • Thermal removal: This technique involves using an iron or an oven to essentially burn through the conformal coating. It’s best for PCBs that require re-working and can be applied to most conformal coating types.  
  • Microblasting: Involves the use of small, mildly abrasive, sharp bursts of air to remove coating. It’s ideal for the precise removal of conformal coating from small areas of the PCB. It works best for epoxy and Parylene-based coatings.     

 Women Technician Working On Computer Parts

IPC Conformal Coating Standards

The IPC (Association Connecting Electronics Industries) has a list of standards to help identify and classify conformal coatings. Conformal coatings fall under three standards:

  • IPC-CC-830C: The Qualification and Performance of Electrical Insulating Compound for Printed Wiring Assemblies. It is the main standard for conformal coatings. The IPC introduced it as a replacement for the MIL-I-46058C standard. It classifies conformal coatings by their chemical compositions, thickness, shelf-lives and appearance. Additionally, it also categorizes conformal coatings based on their resistance to flames, moisture, bacteria (fungi), etc.  
  • IPC-A-610G: The Acceptability of Electronics Assemblies. This standard covers all components involved in electronics assembly, including conformal coating. 
  • IPC J-STD-001F: Requirements for Soldered Electrical and Electronic Assemblies. Since manufacturers apply conformal coating to solder, this standard contains a section addressing materials and applications pertaining to conformal coating related to solder and traces.

 The UL Standards and Engagement also offers two standards pertaining to conformal coating:

  • UL94: This standard categorizes and certifies a conformal coating’s flame resistance.
  • UL746E: Covers how to test materials for properties such as flammability, viscosity, electric and thermal conductance, etc. The listed materials include conformal coating.   

Many of these standards and specifications are “active.” This means that they are updated regularly or as required.  


Do motherboards have conformal coatings?

Not all motherboards have conformal coatings. Certain brands, such as ASRock, use conformal coating as an added layer of protection against dust, extreme temperatures and conductive liquids. 

Does conformal coating prevent short circuits?

Conformal coating insulates traces and other conductors on the board, as well as prevents the growth of dendrites. This can potentially prevent short circuits or at least minimize the risk of them occurring.


When selecting a conformal coating for your PCB, you need to keep functionality and application requirements at the back of your mind. While it is crucial to protect your PCB, ensuring that you protect it with the right materials is vital.

Unlike other manufacturers, we at WellPCB have a team of experienced personnel that will make your conformal coating selection process stress-free. Out entire coatings are made while employing high-quality standards aimed at ensuring enhanced reliability and optimum performance.

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Emma Lu
Our professional engineering support saves our customers a lot of trouble and loss. >>>>>> After you place the order, our engineer will conduct technical reviews to make sure the parts can be mounted well/correctly on the boards. We will check if the component packages match well with the Gerber footprints, if the part numbers you provided match well with the descriptions, and if the polarity is clearly marked. >>>>> When your design is ready, please send your Gerber and BOM so we can quote and start!