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Thin Film Coating Blog

Browse our blog to learn more about thin film and conformal coating processes, material, and application. Find out more about HZO and how our solutions can help your market.

Biocompatible Coatings - Coating Techniques, Applications, More

Biocompatible coatings seamlessly integrate with the human body, offering benefits through their ability to promote healing and prevent adverse reactions. They can improve patient..

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An Overview of Our Parylene Coating Equipment

The original development of our coating technology began in 2007. As a coating company that now licenses thin-film protective layering technology on the back of more than 200..

Read More

Parylene masking equipment

Parylene Masking - General Concepts Explained

Conformal coatings are an excellent way to increase the reliability of electronic components in harsh environments. However, this protection can be too much of a good thing..

Read More

How to Remove Conformal Coating - Which Method is Best?

Conformal coatings are polymeric films applied directly to PCBAs and electronic components to provide a barrier layer of protection from the environment in which they operate...

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Engineer removing Parylene coating

Parylene Coating Removal - Methods & Explanation

In the last blog post in our removing conformal coating series, we discussed removing conventional conformal coatings, such as polyurethane, acrylic, epoxy, and silicone, from..

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Definitive Guide to Conformal Coating Application Methods

Conformal coating materials, including acrylics, epoxies, urethanes, silicones, and Parylene, introduce different benefits, drawbacks, and challenges to any project. Because there..

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PECVD vs CVD – Chemical Vapor Deposition Overview

Thin-film deposition is the dynamic process used for depositing thin-film coatings onto a substrate, part, or assembly. Deposition methods, in general, can be grouped into three..

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Overview of the Plasma Nanocoating Process

Nanocoatings, thin films measured at the nanolevel, serve numerous purposes. But for many product design engineers, the ability to safeguard electronics with protection..

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IoT - Coating Consistency is Key

IoT sensors aggregate and send data to IoT dashboards, simplifying critical, complex decisions quickly. One key area where this is particularly true is the utilization of sensor..

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6 Common Conformal Coating Defects & Their Solutions

When we say that a chain is only as strong as its weakest link, we aren’t talking about polymer chains – we’re talking about conformal coating defects. Regardless of the type, a..

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Conformal Coating vs Potting/Encapsulation - The Pros & Cons

As the world of electronics continues to grow and evolve, printed circuit board assemblies (PCBAs) find their way into more and more products and industries. Whether you create..

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Biocompatible Coatings - Coating Techniques, Applications, More

September 13, 2023 / by Mallory McGuinness-Hickey posted in Protection Capabilities, Coating Process, Coating Properties, Thin Film Applications


Biocompatible coatings seamlessly integrate with the human body, offering benefits through their ability to promote healing and prevent adverse reactions. They can improve patient outcomes, reduce complications, and enhance device functionality. As such, biocompatible coatings have become an indispensable tool in various medical applications.


What is Biocompatibility, and What Affects the Biocompatibility of Coatings?


Biocompatibility refers to the ability of a material to function without causing any harmful effects to the living tissues or organs it comes into contact with.

Several factors influence the biocompatibility of coatings. One such factor is the material composition. The choice of materials used in a coating can significantly impact its compatibility with the human body. Additionally, the surface properties of the coating play a vital role in determining its biocompatibility. Roughness, porosity, and surface energy can affect how the coating interacts with biological tissues and fluids.

When it comes to achieving biocompatibility in coatings, there are key considerations. First and foremost, the material should be non-toxic and non-allergenic. It should not trigger any adverse immune responses or elicit any toxic effects. Furthermore, the coating should withstand the physiological environment it will be exposed to, such as changes in pH, temperature, and mechanical stress.

Coating application processes also play a significant role in achieving biocompatibility. The application technique must ensure uniform coverage and adherence. Proper surface preparation and application techniques are essential to avoid issues arising from poor coating adhesion or inconsistencies.


Why are Biocompatible Coatings Important?

Biocompatible coatings can significantly influence the body's response to medical devices and implants. A well-designed biocompatible coating can minimize inflammatory responses, prevent bacterial adhesion, and promote tissue integration. Furthermore, by providing a protective and biologically compatible barrier, these coatings enhance the safety and effectiveness of medical devices, improving patient outcomes.

There have been several successful applications of biocompatible coatings in medicine and biomedical engineering. Here are a few examples:

  • Orthopedic implants: Biocompatible coatings have been used on orthopedic implants to improve their longevity and reduce inflammation and tissue rejection.
  • Drug delivery systems: Coatings have been developed to encapsulate and protect drugs, allowing for targeted delivery and controlled release within the body.
  • Stents: Biocompatible coatings on stents help to prevent blood clot formation and promote healing in cardiovascular applications.
  • Dental implants: Coatings on dental implants enhance biocompatibility, improving the integration of the implant with the surrounding bone.


Coating Technologies

Various coating technologies are employed to achieve biocompatibility in different medical devices. These technologies involve using specific materials and techniques to create coatings that meet the required standards:

Chemical Composition

Different biocompatible coating materials, including polymers, such as Parylene, ceramics, and metals, are used. Each type has its unique characteristics and advantages for medical applications. Polymers, for example, are known for their flexibility and ability to mimic natural tissues. Ceramics offer excellent wear resistance and can provide a stable surface for cell growth, while metals are valued for their durability and strength.

Coating Techniques

Each coating technique has its advantages and limitations. The selection of a particular method depends on factors such as the desired coating properties, the substrate material, and the intended application. The deposition of biocompatible coatings requires specific techniques to ensure uniformity and adherence to the substrate. Several coating techniques are commonly employed in the medical industry, including:

  • Chemical vapor deposition (CVD): In this technique, a precursor gas is introduced into a chamber and reacts to form a coating on the surface of the substrate. CVD offers excellent coating conformity and is frequently used for coating stents and catheters.
  • Electrochemical deposition: Also known as electrodeposition, this technique involves using an electric current to deposit a material onto a substrate. It is typical for coating electrodes and medical implants.
  • Dip coating: This technique entails immersing the substrate into a bath of the coating material and then withdrawing it at a controlled rate. Dip coating provides a uniform and controlled coating and is often used in the fabrication of medical devices.
  • Spray coating: The coating material is atomized and applied to the substrate in a fine spray. This is a popular technique for coating dental implants and prosthetics.


Biocompatible Coatings Applications

Biocompatible coatings can be employed in manufacturing electronic devices, food processing equipment, and cosmetic products, among others. With their ability to provide a safe and reliable surface, biocompatible coatings offer advantages beyond the medical field.

However, within various areas of medicine, biocompatible coatings play a crucial role in enhancing the compatibility of medical devices, improving tissue engineering techniques, and revolutionizing drug delivery systems. These coatings have transformed the field of medicine by reducing rejection and adverse reactions and improving the overall efficiency of medical interventions. Three use cases are described below.

Medical Implants

One of the critical applications of biocompatible coatings is in the field of medical implants. For instance, in orthopedic implants, biocompatible coatings create an optimal environment for the implant to integrate seamlessly with the surrounding tissues and bones. Similarly, dental and cardiovascular implants benefit from biocompatible coatings, promoting long-term stability and functionality.

Drug Delivery Systems

Biocompatible coatings have revolutionized the field of drug delivery systems by improving stability, enhancing bioavailability, and enabling targeted drug delivery. The efficacy and safety of drug delivery are significantly improved by coating drug carriers such as nanoparticles, microparticles, and implants with biocompatible materials. These coatings protect the drugs from degradation, facilitate controlled release, and ensure targeted delivery to specific tissues or cells.

Biomedical Devices

Biocompatible coatings find extensive applications in various biomedical devices, including biosensors, microfluidic devices, and prosthetics. These coatings enable seamless integration and interaction with biological systems, enhancing the device's functionality and reducing the risk of adverse reactions. For example, biocompatible coatings on biosensors allow accurate and reliable detection of biomarkers, while coatings on prosthetic limbs improve their integration with the human body and enhance user comfort and mobility.


Factors Influencing Biocompatible Coating Selection

Selecting the most suitable material for a specific application is essential to ensure optimal biocompatibility and overall performance of the coating. There are various factors to consider when selecting materials for specific medical applications. These factors include:

  • Chemical composition: The specific chemicals used in the coating formulation can significantly influence its biocompatibility with the surrounding environment.
  • Surface interactions: Understanding how the coating interacts with the surrounding biological tissues and fluids is crucial to ensure proper biocompatibility.
  • Thickness and uniformity: The thickness and uniformity of the coating play a vital role in its ability to protect the underlying substrate and provide the desired properties.
  • Physical properties: The physical properties, such as hardness, flexibility, and adhesion strength, must be considered when selecting a coating for a specific application.

Please contact our engineers if you require a biocompatible coating material for your application or have questions about protective thin film coating properties. Meanwhile, please browse our resource section to learn about other relevant properties, such as tensile strength, yield elongation, and corrosion resistance.

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An Overview of Our Parylene Coating Equipment

June 6, 2023 / by Ryan Moore posted in Parylene, Coating Process


The original development of our coating technology began in 2007. As a coating company that now licenses thin-film protective layering technology on the back of more than 200 patent filings, it can be said that we’ve come a long way since our humble beginnings. HZO now successfully protects millions of complicated digital devices from the ill effects of liquids, sweat, humidity, dust, or other contaminants.

Today we wanted to give a little nod to our origin story and provide a high-level introduction to a material that serves as a building block of our technology.

Learn more about Parylene C and Parylene Type N

Parylene Protection

Parylene (or Poly(p-xylylene) as it’s also known) is a protective layering material deposited with a chemical vapor deposition process. The resulting material is a moisture-resistant, dielectric thin film barrier that has been used for over five decades on a wide range of corrosion-resistant products. Parylene is biocompatible, has good optical properties, and is chemical-resistant. Think big. Think powerful. Parylene has been protecting equipment, components, and products used throughout some of the most advanced industries in the world.

Read more about why Parylene is used 

HZO has developed its proprietary technology utilizing Parylene as a building block and, over the years, has developed its chemistry, specialized processes, automated Parylene masking equipment, Parylene removal processes, systems, and methods of commercialization that together form a powerful and unique conformal protective solution.


Parylene Overview

So why have most people never heard of it? A major obstacle to Parylene becoming more widely adopted in other markets and on many other products, including consumer devices, has been largely due to the cost of Parylene deposition systems and parylene coating material.

Learn more about Parylene coating cost considerations

Not only does the Parylene deposition system and raw material have a history of high price, but over the years, there have been challenges associated with things like scalability, manufacturing integration, device complexity, and what has historically been a manual process for masking and damasking sensitive areas that need to be protected from the protective layering (i.e., the process of protecting certain components from the protective layering material).

To the credit of Parylene companies that have been in that market for much of this journey, the technology has improved dramatically over time, and the material has a sterling reputation in certain markets where development has been focused. But what about other industries that need the same kind of powerful protection?

Learn More Parylene Temperature Range


HZO Parylene Coating Equipment Broadens the Scope


HZO Parylene coating equipment


HZO has broadened the usage scale for this powerful, organic material by making it available to companies and manufacturers that would not have considered it an option until now. The application’s utility is what separates HZO from other companies in the Parylene space.

We talk a lot about the power of the Total HZO Solution. This includes more than our thin-film protective layering technology that protects digital devices from corrosive liquids; it also includes the advances in equipment, integration, and highly specialized processes required to protect some of the world’s most complicated digital devices. Years of driving the technology forward have positioned HZO as the leader in developing custom solutions for digital devices, utilizing Parylene as part of that equation.

These ongoing innovations get passed on to every company we have the privilege of working with, and HZO has made the benefits of Parylene more accessible and affordable to more companies than ever before. As a result, more liquid, sweat and corrosion-resistant products are reaching the hands of consumers. The change in performance is starting to get noticed, and the cry for better protection on consumer devices has never been stronger.

Contact us today to learn more about how HZO is expanding, improving, and repurposing a powerful technology with a proven track record of keeping digital devices safe.


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Parylene Masking - General Concepts Explained

January 28, 2022 / by Mallory McGuinness-Hickey posted in Parylene, Coating Process


Conformal coatings are an excellent way to increase the reliability of electronic components in harsh environments. However, this protection can be too much of a good thing without processes to ensure certain areas remain coating-free.

These polymeric films can inhibit the critical functions of specific functions, but the masking process resolves this issue. With proper masking, you can benefit from conformal coating protection without losing functionality.


What is Masking?

Masking is applying a temporary film, boot, tape, or plug to designated assembly components to prevent them from being coated. While masking is important for conventional coatings such as acrylics, epoxies, urethanes, and silicones, Parylene has unique qualities that create a critical need to ensure it is done right.

Read about Parylene’s optical properties and Parylene biocompatibility.


Quick Introduction to Parylene Masking Techniques

For general guidance on conformal coating masking, the IPC-HDBK-830A handbook provides a good reference. However, because the coating process causes Parylene molecules to penetrate any surface area accessible to air, operators must ensure that all coating keep-out areas resist Parylene coating application, which requires domain expertise.

Read about Parylene C and Parylene N

HZO uses proprietary masking equipment, and our engineers build and customize techniques for every project. However, a short description of general methods follows below.

Parylene masking techniques typically involve precisely sizing materials such as tapes, form-in-place gaskets, and boots to designated masked regions. After applying materials to the appropriate areas, a masking operator will allow peelable masking materials to dry before starting the CVD process, coating the entire component. After coating, the masking material is carefully removed.


Why Proper Masking for Parylene Coating is So Critical

Parylene’s exceptionally high dielectric strength requires you to mask the right areas diligently. A PCBA coated with Parylene would benefit from electrical insulation protection. However, if the connectors on that same PCBA get covered, you won’t be able to plug it in or make connections.

Learn about Parylene Temperature Range

Another reason you must get your Parylene masking process correct is the film's incredible conformality. Where Parylene is allowed to penetrate, pins and moving parts will be completely encapsulated. Although this cohesive and thorough presence of coating is typically considered a benefit, additional cost and labor to remove the Parylene from the keep-out areas will be required with incorrect masking implementation. In other words, it’s best to prevent instead of rework, which can be challenging due to Parylene’s strong chemical resistance properties. 


Why It Can Also Be More Complicated

When you mask for Parylene application, the stakes are higher. Once it’s on, removing the coating will be a struggle without a knowledgeable partner with tools and techniques to make rework easier. The fact that masking for Parylene is also more complex, requiring more skill, raises further complications.

Without skill and experience, masking for Parylene is more challenging than general conformal coating masking due to the chemical vapor deposition process (CVD) used to apply the coating.

Learn about Parylene Thickness 

Unlike conventional conformal coatings applied as liquids, Parylene is applied as a vapor, which means you are masking against a gas. Therefore, a much better barrier is required with the Parylene masking process, as vapor can more easily bypass masking materials.

Other masking considerations include:

  • The need to validate if all components are hermetically sealed or not due to the vacuum nature of the CVD process
  • Chamber maintenance
  • Masking more than just keep-out locations may be required
  • The need for specific fixturing
  • Materials need to be thoroughly cured before coating, and outgassing should be avoided

The list below includes components that, in many cases, should not be coated:

  • MEMs
  • Actuators
  • Mating connectors and pins
  • Test points needed before assembly
  • Ground contacts

Parylene Coating With HZO

Parylene Masking with HZO


If you are masking for Parylene, you must implement the process correctly. Further, Parylene masking requires considerable expertise and experience to identify factors affecting masking success. These might include Parylene masking materials, the Parylene type, and the different areas that must be coated. Proper timing is also essential, as there is a relationship between the masking and coating processes. Any timing issues can impede coating quality. Managing electrostatic discharge is also a concern when masking.

Fortunately, our engineers have years of this experience, creating custom masking plans for customers with electronic products of all sizes, shapes, and functions. We have also developed industry-leading masking equipment that can automate and semi-automate the process for larger productions.

Reach out today if you would like a consultation to discuss why to use Parylene, our scalable Parylene coating equipment, or our automated masking processes that decrease Parylene coating costs

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How to Remove Conformal Coating - Which Method is Best?

June 17, 2021 / by Mallory McGuinness-Hickey posted in Conformal Coatings, Coating Process


Conformal coatings are polymeric films applied directly to PCBAs and electronic components to provide a barrier layer of protection from the environment in which they operate. There are five primary conformal coating materials: acrylics, epoxies, silicones, urethanes, and Parylene. Each material presents its advantages, limitations, challenges, and application methods.

Learn about conformal coating application methods

Acrylic (AR) Conformal Coating Properties

  • Low moisture absorption
  • Relatively short drying times
  • Clear protective coating
  • Good electrical and physical properties
  • Typically brushed, sprayed, or dipped

Epoxy (ER) Conformal Coating Properties

  • Very robust
  • Excellent chemical and abrasion resistance
  • Very rigid conformal coating
  • High dielectric strength
  • Typically brushed, sprayed, or dipped

Read more about epoxy conformal coating

Silicone (SR) Conformal Coating Properties

  • Good humidity and moisture resistance
  • Low toxicity
  • Easy to apply
  • Easy to repair
  • Typically brushed, sprayed, or dipped

Read more about conformal coating application

Properties of Urethane (UR) Conformal Coatings 

  • Moisture and oil-resistant
  • Fungicidal
  • Good flexibility
  • Can be thinned to achieve a chosen viscosity
  • Typically brushed, sprayed or dipped

Read more about polyurethane conformal coating

Properties of Parylene (XY) Conformal Coatings

  • Biostable, biocompatible
  • Excellent chemical resistance
  • Superior conformality
  • Exceptional corrosion resistance
  • Applied by chemical vapor deposition (CVD)

Understand conformal coating vs potting

engineer looking at PCB to determine how to best remove conformal coating

Read the definitive paper on electronic protection methods

Every so often, conformal coatings must be removed. This may be for several reasons, including electrical or functional failures that require rework, PCBA malfunctions, initial design process issues, poor adhesion, conformal coating defects, or improper choice of coating material. Whatever the reason, the first step in the removal process is to determine which coating material you are working with, as this will help determine how to remove the PCB coating.


How to Remove Conformal Coating

Confirm the coating material applied to the PCB you want to remove to determine the best conformal coating method. Confirmation can typically be achieved by either contacting your coating supplier or looking for a JEDEC or IPC label placed on the board. Coatings are designated as AR, SR, ER, UR, or XY, indicating with which coating you are working. If there are no labels, you can still ID the material via methods outlined by the IPC below.

Because each conformal coating has distinct properties, methods such as testing transparency, solubility, hardness, thermal removal, and thickness can show you which type of coating you are working on. For more information, see IPC’s “Coating Removal, Identification of Conformal Coating” guidelines.


Conformal Coating Removal Techniques

After identifying your coating, the next step is to choose the removal technique. Popular methods are briefly discussed below:

Peeling Method

Typically used for RTV silicone or thick rubber coatings, use a dull blade or knife to slit the coating material and peel it off.

Chemical Solvent Method

This process effectively removes urethane, acrylic, and silicone coatings. Prep the area with high-temperature tape and apply solvent using a foam swab.

Grinding and Scraping Method

This removal technique can grind away thin, hard coatings with a micro motor or rotary-style tool or soft coatings with a rotary brush.

Thermal Method

Using low-temperature heat, gently burn and melt the coating material.

Micro Sandblaster Method

This technique involves projecting a fine abrasive powder onto the coating to flake off the material.

engineer observing PCB with equipment


Which Technique is Best for My Conformal Coating Material?

Urethane Coatings

  • Grinding and scraping method
  • Solvent method
  • Micro-blasting method

Acrylic Coatings

  • Thermal removal method
  • Chemical solvent method
  • Scraping and grinding method
  • Micro-blasting method

Epoxy Coatings

  • Thermal removal method
  • Grinding and scraping method
  • Micro-blasting method

Silicone Coatings

  • Grinding and scraping method
  • Micro-blasting method
  • Chemical solvent method
  • Thermal method

Parylene Coatings

Parylene coatings are often harder to remove, but you can typically use the micro-blasting, grinding, scraping, and thermal methods. However, at HZO, we have simplified the reworking process using technology. In the next blog in this series, we will discuss reworking Parylene in general and detail how we simplify the process.

For more information on thin-film coatings for your project, contact us today.

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Parylene Coating Removal - Methods & Explanation

June 17, 2021 / by Mallory McGuinness-Hickey posted in Parylene, Coating Process


In the last blog post in our removing conformal coating series, we discussed removing conventional conformal coatings, such as polyurethane, acrylic, epoxy, and silicone, from components such as printed circuit boards. Parylene coatings, however, present unique challenges regarding rework and removal.

Parylene conformal coatings are unique in their ability to be polymerized and deposited by vapor deposition onto PCBs maintained at room temperature, unlike liquid conformal coating application methods that may lead to coating defects. The result is an extremely thin, pinhole-free, high-purity coating with proven performance for mission-critical applications and consumer electronics devices that must remain reliable.

Read about Parylene Type C and Parylene Type N

Parylene is often superior in barrier properties, uniform coverage, and performance in thinner layers compared to other conformal coatings, with less stress on mechanical structures and virtually no added bulk.

Learn more about what Parylene is used for.

Additionally, Parylene has been trusted for decades due to its remarkable chemical resistance properties to withstand corrosive gases and liquids and maintain performance in extreme temperatures and intense electrical activity.


Want to know if HZO Parylene meets your specifications?


However, the beneficial properties that make Parylene the “gold standard” of conformal coating can also make the material difficult to remove. Thankfully, there are methods you can use to remove and rework Parylene when necessary.

Learn more about Parylene’s benefits, such as Parylene’s optical properties, and biocompatibility  


Why is Parylene Removal Necessary?

From time to time, it is necessary to rework or remove the coating. Perhaps the job specifications changed, or a Parylene vendor incorrectly applied the coating.

One example of poor application is Parylene delamination, in which the conformal coating separates from the coated surface. This results in an unattached, torn, non-conformal coating and an unacceptable finish. Delamination defeats the purpose of Parylene conformal coatings and should be avoided at all costs. Even partial lifting can render the protective coating useless.

There are many sources of Parylene delamination, including standard processes such as demasking, which can create a need for exceptional quality control inspection procedures after production. Other causes include:

Coating porosity: A difference in vapor pressure between the component surface and the Parylene coating creates vulnerability to moisture permeation and intrusion into the substrate. As pressure fluctuations and temperature subsequently occur, osmotic pressures are generated, separating the coating from the component.

Incompatible materials: The component surface and the Parylene coating must bond together for successful coverage. When the Parylene and the surface are incompatible, incongruous surface energies are generated, causing minimal bonding.

Contaminated surfaces: Improperly cleaned component surfaces do not support adhesion.

Regardless of the reason, Parylene removal must be efficient and safe to protect the integrity of the coated substrate material or component.

The following methods are popular ways to approach Parylene removal.


Mechanical Parylene Removal

Parylene’s strong capacity to withstand manipulation, exceptional uniformity, and overall strength means that mechanical removal methods should be used with care, as there is potential damage to the final production. However, as Parylene is a soft polymer, mechanical techniques can be candidates for Parylene removal.

Methods such as picking, cutting, and scraping are effective but run the risk of damaging components, substrates, and delicate track lines. This type of removal requires considerable attention and care. It is possible to achieve good spot removal with appropriate masking, but mechanical techniques may prove undependable for larger-scale surfaces.

Removing Parylene with Micro Abrasion

Micro abrasion is a process performed with automated or handheld human systems that pinpoint a targeted removal area, propelling inert gas or dry air, and abrasive media at the Parylene coating. This removal method is suitable for both whole board and spot removal. It is generally easy to implement, quick, cost-effective, and environmentally friendly.

Thermal Removal

Although Parylene can withstand high temperatures, a high-temperature oven or soldering iron can effectively remove Parylene in specific, small areas. As heat is applied, the coated component rises from the board and lifts off.

Although Parylene can withstand high temperatures, a high-temperature oven or soldering iron can effectively remove Parylene in specific, small areas

This technique may be adequate for small repairs. It is less reliable for large surfaces, but for particular jobs, it can still be an effective means of removal. However, residues and discoloration may occur, and due to Parylene’s high melting point, heat-sensitive substrates may be at risk for damage. Thermal removal can be challenging to manage and is not recommended without the help of Parylene experts.

thermal removal parylene removal method


Parylene Removal with Tetrahydrofuran

Parylene is chemically inert, resisting chemical degradation. However, one chemical has been used to strip Parylene from substrates and components, a colorless organic compound called tetrahydrofuran (THF), with a chemical formula of (CH2)40. This solvent softens the Parylene coating, temporarily loosening the adhesion bond between the substrate and coating. At this point, the Parylene can be lifted off with tweezers. Although THF can be successfully used to remove Parylene, caution must be taken to avoid damaging the coated component, and the solvent should only be used for complete coating removal. For the security of components underneath the coating, it is worthwhile to consider other removal processes before using TFH.

Laser Ablation for Parylene Removal

Laser ablation is a process that removes material from a surface by irradiating it with a laser beam. The beam can cut, drill, or mark delicate materials, providing precise removal. At HZO, a laser ablation process converts Parylene to gas or plasma with pulsed laser sources. This method can be cost-effective for complex removal jobs, results in better quality removal results, and completely Parylene-free areas and 3D devices can be effectively serviced.


There are multiple effective methods to remove Parylene should the need arise. Each method has its strengths, so it’s necessary to know your options and what method will be best for your project.

If you are looking for Parylene removal services or to discuss your project with Parylene experts, please message us today. While removing Parylene can be challenging, if you partner with a company with the best skillsets and processes, the job can be simplified and more cost-efficient. We can also help with scalable Parylene equipment, cost-saving Parylene masking automation, and address other concerns about the cost of Parylene services.

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Definitive Guide to Conformal Coating Application Methods

June 2, 2021 / by Mallory McGuinness-Hickey posted in Conformal Coatings, Coating Process



Conformal coating materials, including acrylics, epoxies, urethanes, silicones, and Parylene, introduce different benefits, drawbacks, and challenges to any project. Because there is no one-size-fits-all solution to unique electronic protection requirements, you must carefully consider these variables and how they may apply to your needs.

Learn how to choose the best conformal coating for your application 

Consideration must also be taken for the conformal coating application method, which includes brushing, spraying, dipping, and chemical vapor deposition. Your choice of application will hinge upon the complexity of the substrate to be coated, required performance, and throughput requirements. Curing time, capital investment, and possible rework and removal due to conformal coating defects may also factor into the overall selection of your conformal coating application method.

This blog post will briefly discuss popular conformal coating techniques and discuss each method’s benefits, drawbacks, and potential challenges.

Understand conformal coating vs potting



brush for conformal coating application

Brush coating is a well-known application technique used to coat a limited quantity of substrates. In this process, the operator formulates coating material, dips a brush into the coating container, and manually applies it to the substrate. With proper application, this method can yield excellent results on even surfaces.

Brush coating is the cheapest and easiest conformal application method, requiring minimal maintenance, repairs, or upgrades. Equipment costs are low, and due to the controlled nature of the process, there is often a reduced need for masking. Although the process is simple, with little capital outlay, the quality and results vary as they are operator-dependent. The process is labor-intensive, and the operator needs proper protection from the coating environment. Obtaining a uniform build over an entire assembly is complicated, and contamination issues are a concern.

Manual brushing is a viable choice for low volumes, such as prototype runs. Brush coating can also be suitable for touchup after repairs or rework. This conformal coating application method also works well for high-topography PCBAs due to the operator’s measure of control.


Advantage Disadvantage
Straightforward and low startup costs Difficult to control the material thickness
Suitable for low-volume, high-mix production Easy to create voids and bubbles
Suitable for rework or touchup application The brush can be the cause of residual FOD (bristles)
Can protect against airborne FOD Operator experience dependent
Very good for small parts or where masking needs are challenging Part to part variability


Read the definitive guide to conformal coating types.



spray coating equipment

Spraying, either manual or automated, is another popular method of application. This technique is faster than brush coating, and when the solvent dilution, pattern, and nozzle pressure are appropriately combined, consistent, reliable results are possible. This method requires masking to shield sections or components of a PCBA before an operator uses a handheld spray gun or automated equipment to apply a thin conformal coating film to the boards.

It may be necessary for complex boards and components for an operator to spray coating on several planes to ensure complete coverage underneath. The feed system type, the material’s temperature, line speed, and atomization pressure affect coating thickness, and viscosity control is critical. If the coating is too thick, the PCBA gets cob webbing. If too thin, wicking and running can occur. Typically, thinning the coating with solvent is necessary for spray application. 

Although spraying costs are low to moderate, more masking time is required than brushing, possibly offsetting the savings. Although spraying may be less expensive than other methods, the temperature and humidity of the coating environment must be conditioned and factored into the startup costs. Additionally, operators should have adequate respiratory equipment.


Advantage Disadvantage
System not complicated Need to contain excess over-spray or any harmful vapors
Reasonable implementation cost Material wastage/loss in the process
Aerosol is suitable for rework Usually much higher in VOCs as dilution is needed for spray
Angled spray may provide a better coating on high-topography assemblies Thin material may require multiple coat/cure cycles to get desired thickness


Dip Coating

dip coating equipment

Dip coating, which can be manual or automated, is one of the oldest coating application methods, effective at applying conformal coatings to assemblies that are not too irregular or bulky in shape. With this technique, units are masked, immersed into a tank of coating material, and subsequently withdrawn. Excess material is allowed to drip off, followed by demasking and curing. Coating thickness is contingent upon immersion and withdrawal speeds. 

Dip coating completely encapsulates the PCBA or component and is a low-cost, efficient process for high-volume applications. Correctly done, dipping yields uniform coverage and repeatable, predictable film thickness. Additionally, both sides of the board coat simultaneously, improving efficiency. That said, the open atmosphere around the dip tank can cause contamination. Consequently, the coating material in the tank must be periodically purged and replaced, potentially increasing costs for high-volume production. Variability of viscosity variations and inconsistent coating thickness can make the dipping process a crude one with little control. 

Dip coating is a popular choice for high-volume production, as carriers may allow for the coating of as many as 40 PCBAs each cycle, equating to around 500 units per hour.

Advantage Disadvantage
System not complicated/easy design Open to environmental impacts – temperature/humidity
Relatively not expensive Material viscosity must be monitored
Reused material/process savings Coating reservoir can become contaminated


Chemical Vapor Deposition (CVD)

Chemical vapor deposition is used exclusively with Parylene coatings. The CVD process is performed under vacuum, with specialized equipment that includes a coating chamber.

Parylene dimer is placed in the vaporizer chamber, and the system is placed under vacuum. The vaporizer is heated to around 150 to 170 °C until the dimer sublimes from a solid to a gas.

The dimer gas travels through the pyrolyzer, heated at a much higher temperature, from 550 to 700 °C, where the dimer is “cracked” into two activated monomers. From there, the monomer travels into the room-temperature deposition chamber and coats everything in the chamber with monomers that connect to other monomers, forming a polymer film.

An overview of the chemical structure changes for this process for Parylene N is illustrated below.


Parylene deposition process for Parylene NFigure 1 Typical deposition process, as illustrated with Parylene N


Since it deposits as a vapor that lands on and begins building up a thin film that wraps around components and substrates with little to no change in thickness or coating defects, Parylene is a truly conformal coating that ensures protection from corrosive environments, even at tight corners.

All surfaces can be coated evenly regardless of chamber position, and the coating deposits the same thickness all around the objects being coated. This vapor phase coating process also leads to pinhole-free coatings, absent of defects. Masking and demasking are typically required, but no curing process is necessary.

However, CVD material and equipment can cost more than other methods, and particular expertise and tools are required for rework. CVD is a batch process, and most CVD equipment yields limited volume.

Advantage Disadvantage
Uniform coverage on all surfaces Batch-mode
Excellent material properties Material/equipment can be expensive
No harmful vapors during the process Requires specific processes for rework


CVD Process with HZO

After reviewing the options above and deciding that chemical vapor deposition with Parylene is an ideal application process for your project, consider HZO. Proprietary CVD equipment with the largest coating chambers in the industry and optimized square chambers addresses many of the limitations of the CVD process. Our dedicated engineers look forward to helping guide you through the coating process from beginning to end, so send a message today.

Watch a webinar on how to incorporate CVD into your manufacturing process.


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PECVD vs CVD – Chemical Vapor Deposition Overview

May 7, 2021 / by Ryan Moore posted in Coating Process, PECVD Coatings


Thin-film deposition is the dynamic process used for depositing thin-film coatings onto a substrate, part, or assembly. Deposition methods, in general, can be grouped into three categories – liquid coating deposition techniques, physical vapor deposition, and chemical vapor deposition. This article will focus on chemical vapor deposition and one of its variants, plasma-enhanced chemical vapor deposition (PECVD).


Download our white paper on choosing the correct coating methodology for your next project:


Chemical Vapor Deposition Methods

Chemical vapor deposition (CVD) methods (including but not limited to CVD, PECVD, and atomic layer deposition, ALD) are done under vacuum, well below atmospheric pressure, as the process deposits layers of material molecule-by-molecule or atom-by-atom. With these techniques, thin-film layers can be deposited in the range of nanometers to sub-20-micron, compared to traditional deposition, which yields coatings at 50-500 microns.

Read "How Small is a Nanometer?" 

No matter the method, vapor deposition produces coatings that alter the substrates’ electrical, mechanical, optical, thermal, and corrosion-resistance properties. The resulting dry coatings are durable and have reached optimal properties without curing at the end of the production cycle.

Below is an overview of the chemical vapor deposition process.


Overview of the Chemical Vapor Deposition Process

The CVD process deposits materials, including Parylene, in a vacuum chamber by vapor deposition polymerization. The item to be coated is exposed to one or more precursors, which decompose or react on the surface. In the instance of Parylene, a solid dimer is vaporized to gas. Before entering the deposition chamber, the gas travels through a pyrolysis chamber that cracks the dimer into two di-radical monomers. The monomers adsorb onto the substrate as a polymer.


an Overview of the Chemical Vapor Deposition Process


Chemical vapor deposition is used to augment substrate surfaces in ways that traditional modification techniques cannot. Polymerization by CVD allows for thin coatings with properties such as lubricity, weather resistance, and hydrophobicity.

Chemical vapor deposition is a repeatable process that produces consistent coverage and reliable results. Applications include:

Many hybrid application techniques arise from CVD, evolving to modify the properties of fabricated thin films. Among these variants, PECVD is a method that can extend the applicability of the technique for reactive and inorganic materials, inert materials, and various precursors. This technique is discussed below.

Overview of the Plasma Enhanced Chemical Vapor Deposition Process

Plasma-enhanced chemical vapor deposition is a variant of CVD; however, it uses plasma energy instead of only thermal energy to deposit thin films. The plasma is typically created by radio frequency, direct current, or microwave discharge that energizes reactant gases, such as silane or oxygen, to form a plasma. The deposition equipment uses a mixture of ions, free electrons, radicals, excited atoms, and molecules to deposit thin-film coatings to the substrate. Parts in the chamber are bombarded with energetic ions (plasma) that form a thin-film layer on the surface made from metals, oxides, nitrides, and/or polymers (fluorocarbons, hydrocarbons, silicones).


PECVD Process Diagram



PECVD-deposited films have excellent physical properties because they are uniform, highly cross-linked, and generally resistant to chemical and thermal changes. Plasma-applied polymers are extensively used in optical coating and dielectric films due to their lower cost and higher efficiency properties. Offering excellent control of material properties (stress, refractive index, hardness), PECVD also produces films used in the semiconductor industry for device encapsulation, surface passivation, and isolation of conductive layers.

Different film compositions can easily be adjusted to produce organic thin films on large substrates (glass and silicon) with varying chemical, thermal, optical, electrical, and mechanical properties. PECVD has also recently been used for many biological applications, including medical device protection, and is also used to avoid corrosion in optical and dielectric devices.

This nanocoating process can use various materials as coatings, including metals, oxides, or silicon, which may offer more flexibility than CVD. Applications include:

  • Fabrication of electronic devices to isolate multiple conductive layers, capacitors, and for surface passivation
  • Solar cells, semiconductor devices, and optically active device applications due to optical, mechanical, and electrical properties
  • Processing of printable electronic devices due to high process efficiency, large-scale patternability, lower cost, and environmentally friendly nature
  • SiN (silicon nitride) PECVD films are used for semiconductor applications due to higher capacitance density, breakdown voltage, and particle performance.
  • SiC (silicon carbide) PECVD films have demonstrated promise in developing high-temperature withstanding MEMs devices.

Read more about nanocoating material

CVD Benefits

When used with Parylene, CVD brings many benefits to the table, including:

  • Ultimate thin-film barrier material for liquid water, water vapor, and harsh chemical corrosion (acid, alkali, organic reagents)
  • Excellent dielectric strength to provide dielectric and insulative protection across an extensive range of frequencies
  • Highly conformal and adherent to many surfaces (metals, glasses, plastics, silicon, ceramics)
  • Entirely non-toxic (safe for all human contact, including implantable devices) and green (non-hazardous processing)

Download our introductory guide to protective coatings


CVD Drawbacks

In comparison with PECVD, CVD can have the following drawbacks:

  • Higher cost: long deposition time (10-20 hrs) need for masking/demasking (80%-line cost), and high precursor (dimer) cost
  • Relatively thick film (typically 10µm minimum thickness needed for high integrity pinhole-free conformal coating)
  • Limited operating range/life due to the aging effects of heat (>50°C), oxygen (air), and UV (sunlight) exposure
  • Low wear resistance and mechanical durability limits use on exterior surfaces (cases, enclosures)

PECVD Benefits

PECVD offers the following benefits:

  • Ability to create “nano”-thin barrier films (50nm+) with low stress (room temperature process)
  • Lower cost: due to fast deposition times (accelerated by RF field) and relatively low cost/low use precursor materials
  • No need for masking/demasking to prevent coating on non-target part areas: the coating may be shielded using the part-holders
  • High tailorability: recipe changes facilitate diverse coating properties, including hydrophobic surfaces, UV protection, oxygen resistance, reworkability, and more

PECVD Drawbacks

In comparison with CVD, PECVD can have the following drawbacks:

  • Barrier performance is weaker than Parylene and highly dependent on the film thickness, layer count, and plasma type.
  • Limited wear resistance: materials are typically soft (enables rework but exacerbates handling issues).
  • Some coatings may be halogenated, raising health and environmental concerns.

Although this article has provided an overview of CVD and PECVD, it is only a high-level discussion. Chemical vapor deposition processes are a good choice for thin-film deposition, but selecting the proper method takes significant experience and technical acumen from a domain expert. HZO offers highly customizable protection solutions with both CVD and PECVD processes. If you have difficulty deciding which thin-film deposition method to use, contact us today to consult with our engineers.

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Overview of the Plasma Nanocoating Process

March 26, 2021 / by Mallory McGuinness-Hickey posted in Coating Process, PECVD Coatings



Nanocoatings, thin films measured at the nanolevel, serve numerous purposes. But for many product design engineers, the ability to safeguard electronics with protection capabilities such as hydrophobicity, corrosion-resistance, and dielectric and thermal properties, is top of the list. Protective nanocoatings empower organizations to mitigate risk associated with downtime, reduce repairs and warranty claims, and cultivate market confidence with remarkably reliable electronic products.

Download our white paper on thin-film coating depositions, including PECVD and a summary of PECVD vs CVD



Plasma Surface Technology Benefits

Plasma application processes can produce nanocoatings with many beneficial substrate surface characteristics, including:

  • Hydrophobicity
  • Oleophobicity
  • Humidity/temperature protection
  • Excellent flammability protection
  • Low dielectric constant with good high-frequency properties
  • Good dielectric strength and high bulk and surface resistance
  • Splash protection
  • High barrier protection against corrosive chemicals and gases while providing low permeability to moisture

These valuable benefits have piqued interest in plasma-based nanocoatings and the processes used for their deposition.

Read "How Small is a Nanometer?"

Plasma Coating Processes

While several methodologies exist to apply nanocoatings to substrates, including plasma spray deposition, plasma-enhanced chemical vapor deposition (PECVD) is popular due to enhanced process control and beneficial physical film properties.


a chart explaining the nanocoating process

PECVD Process


The PECVD Plasma Application Process

PECVD harnesses plasma energy to deposit nanocoatings through several power sources, including microwave discharge, radiofrequency, and direct current. Using PECVD equipment, gases are energized to form a plasma and a mixture of ions, radicals, excited atoms, free electrons, and molecules to deposit the nanocoatings.

Possible materials to form the coatings include metals, polymers (silicones, hydrocarbons, fluorocarbons), oxides, and nitrides, representing many possibilities. The resulting films are highly cross-linked, dense, pinhole-free, and uniform; these attributes lend to good physical properties.
The process offers precision control over these film properties, yielding various chemical, thermal, mechanical, electrical, and optical benefits.


HZO PRO800-PL Proprietary Nanocoating Coating Equipment

HZO PRO800-PL Nanocoating Equipment


PECVD Parameters to Consider for Optimal Performance

Internal and external plasma parameters may be modified to affect the resulting film. Internal plasma parameters include the precursors used, the distribution of various species in the plasma and the species’ energy, and the homogeneity of discharge. External parameters include temperature, applied power, total pressure, gas flow rates, pumping speed, and reactor geometry.

PECVD Benefits

The deposition process allows for a wide range of material usage, including unconventional precursors that can deposit on surfaces with complex geometries, typically at lower temperatures than other vacuum deposition processes, such as thermal chemical vapor deposition. It is possible to tightly and efficiently control these precursors while generating few by-products, allowing for precise film composition and uniformity control. As a result, PECVD nanocoating chemistry is unique and often unobtainable with standard liquid coating deposition methods.


PECVD Applications

PECVD coatings are used in applications that require lower cost and high efficiency, including optical coatings, corrosion resistance, and dielectric films.

Applications include:

  • Mobile phones
  • Earbuds
  • Smart speakers
  • Wearables
  • Outdoor cameras
  • Hearing aids
  • Catheters
  • Smart patch
  • Connected health devices
  • Automotive in-cabin sensors and electronics
  • Automotive cabin filters
  • Automotive cameras
  • Doorbell cameras
  • POS scanners
  • Air quality sensors
  • Smart home applications
  • LEDs
  • Drones
  • HVAC sensors
  • Industrial equipment controller

PECVD Coatings with HZO

At HZO, our in-house designed deposition equipment is optimized for faster deposition rates with scalable reactors for High-Volume Manufacturing (HVM). The fixtures used during the deposition process (directional plasma only) provide an alternative to masking, a process used to ensure coating does not cover parts such as connectors. This alternative can save time and money, as masking and demasking can be labor-intensive.

  • Plasma-based technology leverages a variety of chemistries that can quickly be adapted to specific requirements.
  • Coatings can be single or multi-layer, with one or more chemistries applied. This hybrid approach allows the delivery of target properties.
  • Materials include halogen-free alternatives.
  • Typical thickness varies from 300 nm to 3 µm.
  • Masking requirements can generally be addressed in the chamber as part of the deposition process using a shadow mask to isolate areas to be kept free of coating.
  • Minimal footprint required to perform coating operation.
  • Features include liquid protection, anti-corrosion, etc.
  • Solutions are scalable for high-volume manufacturing at competitive pricing.

Download the HZO Sentinel Series™ Datasheet


For more information on our plasma-based nanocoatings, please contact the HZO team with any questions or concerns. Our engineers would love to give you a free consultation to determine if the plasma nanocoating process is ideal for your application.

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IoT - Coating Consistency is Key

September 25, 2020 / by Mallory McGuinness-Hickey posted in Parylene, Coating Process, Coating Properties, Value of Coatings



IoT sensors aggregate and send data to IoT dashboards, simplifying critical, complex decisions quickly. One key area where this is particularly true is the utilization of sensor data for predictive maintenance, a process that reduces downtime and lowers the total cost of ownership. Myriad other applications incorporate these “smart” sensors too.

Today, IoT sensors are ubiquitous, touching almost every aspect of life. Gas pressure sensors monitor pressure changes in oil, energy, and utility applications. Photoelectric devices (photo sensors) are now common in the consumer electronics vertical. Sensors are responsible for temperature monitoring, a typical use case for warehouse and inventory management, and HVAC systems monitoring.

Accelerometers detect subnormal industrial machine applications, while ultrasonic flow meters are coupled with IoT modules to send data about smart metering to a remote location. Moisture sensors have been critical in recent advances in smart farming, allowing for constant soil health monitoring. In the automotive sector, tunneling magnetoresistive sensors (TMR) are an increasingly popular way to measure mechanical displacement. And Particulate Matter sensors detect pollution in the industrial landscape and smart cities.


The chemical vapor deposition (CVD) process used to deposit Parylene conformal coatings can efficiently accommodate these complex surfaces. Parylene’s usefulness is primarily founded upon its ability to cover PCBA configurations with exposed internal surfaces, sharp edges, flat surfaces, points, and crevices with consistent coverage free of voids.


HZO PRO750 Parylene Coating Equipment

HZO PRO750 Parylene Coating Equipment


The Parylene Deposition Process – Consistent Coverage

Rather than dipping, spraying, or brushing pre-formulated layers onto PCBAs and other components, Parylene’s application method synthesizes the protective film in-process. This deposition system comprises a series of vacuum chambers that produce Parylene vapor, pyrolyze the vapor, then deposit the vapor as a polymer sequentially.

During the CVD process, gaseous Parylene penetrates the layers of a PCBA. Its vaporous consistency surrounds all areas as it builds coating protection along the exterior. The coating layers are substantially thinner than those provided by liquid conformal coating materials, enhancing reliability and functional versatility.

It has repeatedly been demonstrated that CVD is valuable for thin-film deposition on irregular PCBAs. CVD's Conformal layers are exceptionally uniform, even in the nanometer range. Because these coating layers are exceptionally thin, non-uniformity is minimal.


Reach out to an Expert 

Choosing Parylene conformal coating services isn’t a failsafe decision, like anything else. Problems can occur with the process and the material. This is particularly true if the wrong Parylene type is used for a coating project while another type could provide better coverage. If you need a consultation to determine if Parylene is the right choice for your project, contact the HZO engineering team today, fill out a quote form, or leave a brief message.

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6 Common Conformal Coating Defects & Their Solutions

June 16, 2020 / by Mallory McGuinness-Hickey posted in Conformal Coatings, Coating Process


When we say that a chain is only as strong as its weakest link, we aren’t talking about polymer chains – we’re talking about conformal coating defects. Regardless of the type, a single coating defect can affect the long-term reliability of a PCBA or component and must be repaired or removed. This can be costly and labor-intensive.

Therefore, it’s best to avoid defects from occurring in the first place. The following is a list of common defects and how to keep them from cropping up during your conformal coating application.


The 6 Most Common Conformal Coating Defects and Solutions


Capillary Flow

Capillary flow, also known as scavenging, occurs when a conformal coating migrates from one area of a PCBA to another, leaving behind an inconsistent, uneven finish on the surface.

Common causes for capillary flow include:

  • The application of too much coating
  • Conformal coating with low viscosity or high surface tension
  • Low surface energy of component being coated

To avoid capillary flow from occurring:

  1. Ensure that the PCBA is entirely clean before coating.
  2. Use solvent-based coatings instead of water-based, and decrease the use of thinners to increase viscosity.
  3. Before coating, heat the board to decrease dry time.

Learn more about epoxy conformal coating.


Cracking and Ripples

Cracking and ripples can compromise a conformal coating film, exposing a substrate or PCBA to potential contaminants.

Common causes for cracks and ripples include:

  • Coating that is too thick
  • Thermal shock
  • Coating that has been cured too quickly

To avoid cracks and ripples:

  1. Always apply the coating at an appropriate thickness.
  2. Allow for extra drying time at room temperature.
  3. Consider selecting a coating with a broader effective temperature range.


De-wetting is when a conformal coating will not evenly coat the surface to which it is being applied.

Many things cause dewetting, including:

  • An uneven coating application
  • An improper mixture of two-part materials
  • Residue on the coating surface
  • Variations in Surface Tension and Surface Energy

To avoid dewetting, thoroughly clean the material being coated before application.

Learn more about polyurethane conformal coating


a printed circuit board experiencing dewetting



Delamination occurs when a coating has lifted away from the substrate. This hinders protection because the area below the coating is left exposed.

Delamination has many causes, including:

  • Too thick of a coating
  • Coating not adhering to the previous coating layer
  • Contamination on the coating surface prevented a good bond to the surface

To prevent delamination:

  1. Reduce the thickness of the coating.
  2. Thoroughly clean the substrate before coating.
  3. Apply a “primer material” that can bond with the substrate and material used for conformal coating.

Orange Peel

Orange peel is when a coating appears dull, resembling the skin of an orange.

It is caused by conditions including:

  • A substrate that is too hot
  • Improper coating mixture or solvent ratio
  • A local environment that is too dry during application
  • A second coat has been applied before the first coat is dry

To avoid orange peel:

  1. Apply coating at the specified thickness.
  2. Reduce the viscosity of the coating.

Learn more about conformal coating vs potting


Air bubbles, Pinholes, and Foam

Bubbles occur when pockets of air get trapped under a conformal coating layer. Foam is an extreme form of bubbling, and sometimes bubbles burst through the conformal coating, forming a pinhole.

Bubbles, pinholes, and foam happen when:

  • A coating is too viscous
  • The coating is too thick
  • Application equipment has not been setup correctly

To avoid air bubbles, pinholes, and foam:

  1. Use a lower viscosity conformal coating
  2. Ensure the coating is applied at the recommended thickness.
  3. When applying the coating, do so with thin coats.

Why This Doesn’t Happen at HZO

At HZO, we use a conformal coating application method called chemical vapor deposition (CVD) that circumvents these conformal coating issues. Using CVD, we produce uniform, pinhole-free conformal coatings every time. Contact us today to speak to an expert if you want to hear more about our proven technology and processes.

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Conformal Coating vs Potting/Encapsulation - The Pros & Cons

June 11, 2020 / by Mallory McGuinness-Hickey posted in Conformal Coatings, Coating Process


As the world of electronics continues to grow and evolve, printed circuit board assemblies (PCBAs) find their way into more and more products and industries. Whether you create products for consumers, the automotive industry, the military, or some other field, PCBAs play a big part in your product design. You’ll need to protect them without impeding the rest of your design.

You have a few options for coating a PCBA: conformal coatings or potting and encapsulation resins. These organic polymers provide chemical and thermal resistance and electrical insulation to the delicate PCBA beneath them. But that’s where most of their similarities end. This guide will discuss the differences between encapsulation resin and conformal coating and their effects on a PCBA.


What’s the Difference Between Conformal Coatings and Potting?

While both potting/encapsulation and conformal coatings protect a PCBA, they do so differently.

Electronic encapsulation seals a PCBA within a thick resin layer to protect substantially against physical shock, chemical exposure, and excellent electrical properties. Usually, this resin is dark-colored, so you won’t be able to see the board underneath it. The resin is mixed with a hardener before application, which allows it to cure a cross-linked polymer.

So, what is potting? While “encapsulation” and “potting” are used interchangeably, potting sometimes refers to the process used for PCBA encapsulation.

Alternatively, a conformal coating is a protective dielectric layer that is non-conductive. It protects from dangers like salt spray, fungus, moisture, and corrosion. The film, composed of epoxy conformal coating, acrylic, or silicone, is very thin and lightweight, having almost no dimensional effect on the PCBA or added stress to the components. Processing and applying this single-component material is easy and versatile, providing flexible options for the finished product.

Learn More About Conformal Application Methods

While traditional coatings are single-component, some newer ones use a two-part process with polyurethane conformal coating to blend the protective aspects of PCBA potting with the flexibility of coatings. Plus, they don’t use solvents, which reduces concerns about volatile organic compounds (VOCs) present in many low-viscosity single-component coatings and adversely affects people and the environment. Fortunately, even those have come a long way, as most manufacturers have worked to reduce VOCs in their coatings.


Which Is Better to Protect My PCBA — Conformal Coating or Potting?

To best protect your PCBA, you’ll have to consider several factors of your product and how PCB resin coating and potting contribute to them.

Environmental factors play a significant role in choosing a protective material. Will your PCBA be exposed to any of the following?

  • Extremely high or low temperatures: You will have to consider the way resin can behave during use in extreme temperatures, how sudden or gradual the change is, and how heat could affect production. Resin generates a lot of heat when mixed with its hardener, which can cause damage to the PCBA or the housing if it gets too hot.
  • Water, humidity, or moisture: Some conformal coatings are less waterproof than others. While the resin is typically always waterproof, you’ll have to double-check that your coating is, too.
  • Physical shock: If your component might be exposed to heavy physical shock, the resin can help spread the impact across the material and reduce or eliminate the damage to the PCBA.
  • Mechanical stress: Abrasion and scratches can become problematic in environments like assembly lines and manufacturing equipment, where high speeds and volumes are typical. Resin provides a thick layer to protect against that physical threat.
  • Chemical exposure: If your PCBA could be exposed to harsh chemicals, both resin and coatings provide exceptional protection from exposure and submersion.

While PCBA potting offers more protective benefits, coatings hold the upper hand in design flexibility and can still protect products in everyday environments, like consumer electronics. Only those that are in particularly challenging environments typically need PCBA encapsulation.


a printed circuit board being encapsulated with a coating


Below are some design factors that factor into the debate:

  • Weight: Resin adds a thick block of material on top of the board, significantly increasing its weight. In many products, heavyweight components aren’t an option.
  • Thickness: Many products can’t function with the added thickness of the resin added to their design.
  • Workability: Since resin is dark and thick, you can’t see through it or easily remove it to rework the board. It could rip up the PCBA if you tried to take it off. Coating, on the other hand, is usually clear, which allows you to see through it and make adjustments if needed. This helps address any conformal coating defects
  • Housing: If the housing of the PCBA doesn’t offer much protection, the resin may be a way to protect it more thoroughly. Coatings are often used as secondary protection within well-built housing.
  • Application: Depending on the design requirements, one option may be better for production. Resin can add risky heat during application and takes longer to cure. Conformal coatings tend to be quick-drying and can be applied in several ways, such as painting it with a brush, spraying it on, dipping the PCBA, and using robotic systems.

Conformal coatings are an excellent way to protect a PCBA from common threats without paying for the added weight and cost of encapsulation.

Here at HZO, we use a coating called Parylene, which is biocompatible — meaning it’s great for the medical devices industry — and extremely thin. It is clear and excellent for waterproofing and liquid protection.


Pros and Cons of Potting/Encapsulation

Designers often choose PCBA encapsulation for products in heavy-duty environments, as it protects against many damaging agents.

Some of the benefits of PCBA potting include the following:

  • Provides added protection against chemical, thermal, and physical risks, including water and shock.
  • Offers better performance for high-speed and high-volume work in industrial environments.
  • Has VOC-free options.

Some disadvantages of PCBA potting are:

  • It makes it difficult to inspect or rework the PCBA.
  • Causes possible design issues due to the added weight and thickness.
  • A more complex application process, especially regarding heat and two-part mixing.

Pros and Cons of Conformal Coating

Conformal coating is more popular than potting. It protects many consumer products outside dangerous exposure environments and provides more design flexibility. However, if your product is used in rough applications, it may not offer all the necessary protections.

Here are some of the pros of conformal coatings.

  • Thin and lightweight, offering superior design flexibility and no stressed components.
  • Offers protection from low-level issues like salt spray, dust, moisture, and corrosion.
  • Offers a variety of application methods.
  • Newer options with low VOCs.
  • Long lifespan.

The negatives of conformal coatings include:

  • Offers less robust protection against heavy-duty threats.
  • Contains VOCs within the solvents, though these are becoming less abundant.

Contact Us Today to Protect Your PCBA

If you’re still unsure about which option is best for your PCBA, our expert team of HZO engineers can help. We realize that your needs are just as unique as our coatings, so we will work closely with you to provide custom coating solutions.

To learn more, contact us or call us today at 1-877-757-4496.

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