The ABCs of ultra-thin fluoropolymer coatings for electronic circuit boards

May 9, 2017 alternative, Blog, conformal coating, Fluoropolymer

Nano coatings are no mask conformal coatings with great water repellent properties

What is a fluoropolymer coating?

A fluoropolymer coating is typically comprised of fluorocarbons and characterised by carbon-fluorine bonds.

They have many interesting properties and especially for printed circuit boards. However the three key properties for electronics are that the coatings are:

Hydrophobic
Chemically resistant
No masking required

These properties can be key to protecting the electronics and providing a highly cost effective production process.

Hydrophobic coating

Fluorocarbons are not susceptible to Van der Waals force.
This gives the coatings their signature characteristics. That is they are non-stick, hydrophobic and friction reducing.
Therefore, water does not like to wet the surface of the circuit board and this gives the circuit excellent protection.

Chemically Resistant

These fluorinated coatings are chemically inert.
Owing to the fluorine bonds, fluoropolymer coatings demonstrate a high level of durability as well as resistance to acids, bases and most solvents.
This gives the circuit board a high degree of protection from chemical attack.

No masking required

Finally, what is really interesting is that these properties are exhibited at ultra-thin film thicknesses. Typically a dry film can be 1-2um or even less.

This means that masking generally is not required for circuit boards before application. Therefore, you can dip the whole product into the liquid and there is no issue with electrical contact. This can lead to significant cost savings in production.

Find out more about our range of fluoropolymer nano coatings here.

What other properties do the fluoropolymer coatings have that may be relevant in electronics?

SCHUK 2

As already mentioned these hydrophobic coatings have very specialised properties.

They can include:

Being highly hydrophobic (water repellent)
Having a high moisture barrier
Requiring no masking before application
Being highly oleophobic (oil repellent)
Having a high chemical resistance
Having a high lubricity
Having high dielectric properties
Providing high corrosion resistance
Providing good abrasion / wear resistance

Note, not all fluoropolymer coatings have all of the above properties. But, some coatings can in fact have almost all of the properties.

The fluoropolymer coatings are extremely flexible coatings and becoming more prolifically used throughout engineering.

What sectors of industry are fluoropolymer coatings being used in protecting electronics?

SCHUK3

Fluorinated coatings are used to protect electronics in almost all industrial sectors.

They include:

Aviation
Aerospace
Defence
Automotive
Industrial
Oil & Gas
LEDs
Medical
Optics
Telecommunications
White goods / Commercial

This list is limited and there are a lot more areas that they are used.

What are the major differences between a fluoropolymer coating and a conformal coating for protecting an electronic printed circuit board or assembly?

There are several key differences between a conformal coating and a fluoropolymer coating.

They include:

Hydrophobic Properties – A fluoropolymer coating is generally hydrophobic in nature. It repels water when the water is on the surface of the coating.
Extremely thin coating – The fluoropolymer coating is normally applied a lot thinner than a typical liquid conformal coating. This is due to its superior performance when repels liquids
No masking – Due to the extremely thin fluoropolymer coating applied (<1-2um), the components that normally require protecting (connectors, switches etc) from the insulating liquid conformal coating may not need to be masked for the fluoropolymer. The circuit board can be completely submerged in the liquid with no masking applied without fear of damaging the connections.
Simple process – No masking means an extremely fast application process
Fast drying – due to the thin nature of the fluoropolymer coating and the solvents normally used the coating dries extremely quickly.

Find out how we can help you with your ultra-thin hydrophobic coatings now.

How to Remove Parylene From a Printed Circuit Board

May 4, 2017 Blog, Parylene

conformal coating rework collage 640_SCH UK

Removing conformal coatings from a printed circuit board (PCB) is a hard process to do well. Removing Parylene coating is even more difficult.

The problems are many but a key reason is that the Parylene coating itself is chemically inert. It has a very high chemical resistance so the solvents don’t work well. This means any chemical attack tried with solvents or other liquid chemicals on the Parylene is as much likely to damage the circuit board than remove the actual coating.

This leaves the basic option of mechanical abrasion.

Mechanical Abrasion

Mechanical abrasion is a well known method for Parylene Removal. It can be done crudely by scraping off the Parylene with a knife or tool. Or, removal can be done with a media blast system like a Vaniman Problast system that gradually erodes the Parylene coating away.

However, mechanical abrasion is a time consuming process and is highly skilled. Also, it tends to be a localised repair and removal technique.

The concept of completely removing all of the Parylene off a circuit by mechanical abrasion is considered almost impossible unless a ridiculous amount of time and effort is injected into the process.

Find out now how much money you can save by using our Parylene removal service

We are happy to provide a quotation for removing Parylene through our coating services so you can see for yourself how much you can save.

Contact us now to request your quotation for complete removal of Parylene from a circuit board. Or, give us a call at (+44) 1226 249019 or email your inquiries at sales@schservices.com

Improve your conformal coating masking process reliability with custom boots

May 2, 2017 masking boots

Customer case study showing over 60 percent reduction in conformal coating masking costs after switching to reusable masking boots

One of the most overlooked advantages of reusable conformal coating masking boots is the improvement they bring to process reliability and consistency. Unlike masking tape, well-designed boots provide a repeatable mechanical seal that is far less prone to leakage during coating.

When correctly specified and fitted, a masking boot physically prevents conformal coating from entering connectors and interfaces. This is inherently more reliable than tape-based masking, where small gaps, wrinkles, or edge lift can easily allow coating ingress.

Tape masking is also highly operator-dependent. Achieving a reliable seal requires sustained attention, experience, and manual precision. Even skilled operators must work slowly to avoid leaks, increasing cycle time and fatigue-related errors.

In contrast, masking boots significantly reduce skill dependency. They are quicker to apply, easier to inspect, and deliver consistent results across operators and shifts. The outcome is fewer masking failures, less rework, and improved first-pass yield.

By reducing variability at the masking stage, reusable boots help stabilise the entire conformal coating process — lowering repair rates, protecting critical components, and improving overall production robustness.

Therefore, not only do you save up to 60% of your conformal coating masking costs due to reduced process times with boots but you can also improve the reliability of the masking process.

Need to know more about conformal coating masking boots in your application process?

Contact us now and we can discuss how we can help you. Call us on +44 (0) 1226 249019, email your requirements on sales@schservices.com, contact our distributors direct or complete the details in the contact form.

How thick should I apply my conformal coating?

April 27, 2017 Uncategorized

So, a question I am regularly asked is,“What is a good conformal coating thickness for my printed circuit board?”

Well, the simple answer is thick enough so the conformal coating works and protects the circuit board. But not too thick as this can cause problems for the circuit board in the long term.

After all, the performance of the conformal coating is dependent on the material applied. But, it is possible to quantify this a little more.

Help for determining the right conformal coating thickness

First off it’s probably best to use guidelines from International Standards like IPC A 610. These standards specify the conformal coating thickness based upon the generic material types like acrylics, polyurethanes, and silicones. Further, you can also reference this data against the material manufacturers technical recommendations.

Combining these two pieces of information should give you a target range for a suitable thickness. However, ultimately, the coating thickness is down to the user.

How you decide if the conformal coating thickness is good enough is up to you. Too thin and you will not protect the circuit as effectively as you may need. Too thick and you could have reliability issues in the future. So, monitor your conformal coating thickness with care.

So what do the IPC Standards recommend when considering coating thickness?

The IPC A 610 standard defines ideal thickness values as:

Acrylic: 30-130μm
Polyurethane: 30-130μm
Silicone: 50-210μm

However, this is not the end of the story. Using the target coating thicknesses as an absolute value can be problematic.

The reality is that the thickness will vary massively across the circuit board due to many factors including the surface tension of the liquid, the surface energy of the board surface, the design of the board, the material properties and the application method used.

So, there may be areas on the board that could fall outside of the range where the coating thickness will be less or more than the ideal values. Therefore, it is highly recommended that the range should be considered as an average value across the board for the conformal coating thickness.

In fact, the IPC go further and suggest using flat test coupons coated in the same way as the process you use for the circuit boards. Then, these test coupons are measured against the standards. In the end how you decide if the coating thickness is good enough is up to you.

Too thin and you will not protect the circuit as effectively as you may need. Too thick and you could have reliability issues in the future. So, monitor your conformal coating with care.

Learn more about the different methods for measuring the thickness of conformal coating here. Find out more about conformal coating thickness targets and how they are defined by chemistry and function through our knowledge hub.

Need to know more about measuring conformal coating thickness in your application process?

Contact us now and we can discuss how we can help you. Or, give us a call at (+44) 1226 249019 or email your inquiries at sales@schservices.com

Find out how one company saved 60% of their process costs by changing to custom conformal coating masking boots

April 25, 2017 Blog, masking boots

Diamond MT, a conformal coating and Parylene coating service provider in the USA, found they saved more than 60% of their current costs by switching to the SCH range of conformal coating masking boots.

Sean Horn, Diamond MT, explains how they did it.

“We had initially wanted to try SCH’s conformal coating masking boots for price savings. However, once we began to work with Lee on our specific masking application, we realised that we could extend the life of our boots over 200%. We switched immediately!

We then realised the importance of working with someone who understands coatings. We will not being going back to our previous supplier.”

Sean Horn, Director, Diamond MT, Parylene and conformal coating subcontract service provider.

So why did Diamond MT switch to our range of masking boots?

When the analysis was completed, it was found pricing for our conformal coating masking boots was lower by 30% compared to their current supplier. This made a significant saving to Diamond MT and immediately a trial production run was started.

What was really interesting was after using them in the first month, Diamond MT found the masking boots lasted twice as long as their original boot from the alternate supplier. This meant that now Diamond MT has halved the volume of boots they order and this has reduced their costs by 60% for the year.

What started as a simple trial led to a huge saving to Diamond MT as a partner with SCH.

Diamond MT saved more than 60% of their masking costs by switching to reusable conformal coating masking boots from SCH Services

Diamond MT reduced their masking costs by more than 60% after switching to SCH’s reusable conformal coating masking boots.

Read our article in the Conformal Coating Masking Knowledge Hub on Reusable masking boots and find out how they give fast, repeatable seals around connectors and keep-outs, so you can lift first-pass yield and cut masking labour.

Need to know more about using conformal coating masking boots in your application process?

Contact us now and we can discuss how we can help you. Give us a call at (+44) 1226 249019 or email your inquiries at sales@schservices.com

How do I correctly dip coat my circuit board in conformal coating?

April 21, 2017 Blog, conformal coating

The dip process for conformal coating is a method used to coat printed circuit boards for a very long time. The process in its simplest form is as follows:

The printed circuit board (PCB) is lowered into a tank of coating.
This can be complete submersion or partial dip.
The board can be dipped vertically, horizontally or at another angle.
The board can be dipped manually or automatically.
The board is removed from the coating and the excess coating drains away.

This process is highly effective in applying a conformal coating to a printed circuit board (PCB).
Dip conformal coating process showing a PCB being immersed using dip coating equipment for consistent, high-volume application

A simple approach involves dipping a circuit board by hand into a container of conformal coating, which can deliver acceptable results for low-volume work. However, dedicated dip coating equipment is typically used—particularly for medium- and high-volume production—where consistency, control, and repeatability are critical.

What equipment may you need for dipping circuit boards?

The reason for using dipping machines in conformal coating is because the process has variables that are critical to film integrity and they are controlled by the system. The variables that are critical for film quality and thickness are:

The speed of immersion
Dwell time in the coating
The withdrawal speed of the board

These factors, plus the viscosity of the conformal coating, are important to create a high quality finish and reduce costs.

How cost effective is the dip process for conformal coating?

The conformal coating dip process itself can be extremely low cost. The cost of a dip system can be low compared to many other processes and when balanced against the speed of application.

However, if the circuit board demands a lot of components be masked before processing then the overall coating process can be expensive. Masking for dipping can be very demanding and very difficult to complete successfully.

Find out more about effective masking strategies for dip coating at our Conformal Coating Masking Hub.

Need to know more about using a conformal coating in your application process?

Contact us now and we can discuss how we can help you. Give us a call at (+44) 1226 249019 or email your inquiries at sales@schservices.com

How do I brush coat my conformal coating?

April 18, 2017 Blog

The correct technique for applying conformal coating by brush is to flow the coating on.

The material should not be brushed on like you are decorating with paint. The coating should be loaded on to the brush and flowed onto the printed circuit board.

*The correct technique for applying by brush is to flow the conformal coating on to the circuit board. The material should not be brushed on like you are decorating with paint.*

What conformal coatings can be applied by brush?

All conformal coatings can be applied by brush and most lend themselves well to the technique. The key points to be aware of are the material pot life and the conformal coating viscosity.

Material pot life. The pot life of the material may be finite so the conformal coating could cure during use. This may make the material useless to apply after a certain amount of time.
Conformal coating viscosity. The way the conformal coating flows is critical when applied by brush coating. Therefore, the viscosity of the coating material is highly influential on the flow so control of the viscosity is critical to allow good coverage.

What Factors Control the Quality of Conformal Coating Finish with Brushing?

Although brushing is often considered the simplest conformal coating application method, achieving a consistent, defect-free finish requires careful control of several interacting variables. Unlike automated processes, brushing relies heavily on human input, making process understanding and training especially important.

The key factors that influence coating quality when brushing include:

Operator skill and technique – Brush loading, stroke direction, pressure control, overlap, and rework handling all directly affect film thickness, edge definition, and defect formation. Inconsistent technique is a common cause of bubbles, streaking, and uneven coverage.
Brush quality and selection – Bristle material, stiffness, tip shape, and cleanliness determine how evenly the coating is deposited. Poor-quality or worn brushes can introduce fibres, air entrapment, and surface texture defects.
Viscosity of the conformal coating – Coatings that are too viscous may leave heavy brush marks or uneven films, while overly thinned coatings can lead to runs, pooling, or insufficient coverage. Viscosity must be matched to both the coating chemistry and the brushing technique.
Coating environment – Temperature, humidity, airflow, and cleanliness influence solvent evaporation, levelling, and cure behaviour. Uncontrolled environments can increase the risk of bubbles, contamination, and poor surface finish.
Board size, layout, and complexity – Dense assemblies, fine-pitch components, connectors, and vertical features increase the likelihood of shadowing, wicking, and thickness variation when brushing. Design choices can significantly impact how practical brushing is as an application method.
Conformal coating material type – Acrylics, silicones, polyurethanes, epoxies, and UV-curable coatings all behave differently under manual application. Dry time, reworkability, solvent content, and levelling characteristics must be understood to avoid defects.

The Role of Training in Brushed Conformal Coating

Because brushing is highly operator-dependent, training is one of the most effective ways to improve quality, repeatability, and yield. Structured training helps operators understand not just how to apply a coating, but why defects occur and how to prevent them.

SCH provides conformal coating training covering:

Correct brush selection and handling techniques
Coating preparation, thinning, and viscosity control
Defect recognition (bubbles, streaking, dewetting, pinholes)
Environmental control and best-practice setup
Inspection criteria aligned with IPC standards
Rework and repair considerations for brushed coatings

Training can be delivered as part of a wider process review or focused specifically on manual application methods, helping manufacturers reduce rework, improve consistency, and build operator confidence.

To learn more, explore our conformal coating training programmes or review our wider guidance in the Conformal Coating Processes Hub, which covers brushing, spraying, dipping, selective robotic coating, and Parylene deposition.

Need to know more about using a conformal coating in your application process?

Contact us now and we can discuss how we can help you. Give us a call at (+44) 1226 249019 or email your inquiries at sales@schservices.com

How Do I Measure Conformal Coating Thickness?

April 13, 2017 Blog

There are several ways to measure the conformal coating thickness on a printed circuit board (PCB). They can be either used on dry or wet film coating.

These techniques include:

Non-destructive eddy current system
Micrometer screw gauge
Wet film gauge

These techniques are explored further below. Alternatively, click through to our article Conformal Coating Thickness Measurement: Wet, Dry & Optical Methods to get a more detailed review.

Non-destructive eddy current system

A fast method for measure coating thickness is a system using eddy currents. The process can be extremely quick and accurate to ±1 um.

Using a gauge and flying probe for the measurement the system is extremely easy to use. The process works by placing the test probe head flat on the surface of the conformal coating and the measurement is almost instantaneous. The system provides an immediate repeatable result for thickness measurement of conformal coating.

Using a test probe system like the Positector 6000 can quickly give you conformal coating thickness measurements without damaging the circuit board.

Test coupons are the ideal method for measuring the coating thickness, whether is it spraying or dipping, and can be kept as a physical record of the performance.

Apply the coating to the test coupons at the same time as the circuit board then provides a permanent measurement and an accurate guide to the coating thickness.

There are a couple of issues using a system like this.

First, there needs to be metal in the circuit board directly below the tested point. Otherwise, the system cannot work.

Second, there needs to be a flat area large enough for the test probe. The smallest practical probe is approximately 6mm diameter so any area smaller than this is not practical.

Finally, the surface measured for the probe needs to be flat. If not then there will be errors in the measurement.

Micrometer screw gauge

The low cost method is using a calibrated micrometer screw gauge that can measure down to ± 10 um. First measure a point on the board or test coupon, apply the coating, cure and measure the test coupon again at the same point. The difference gives you the coating thickness.

A couple of pitfalls to avoid are ensuring the coating is cured hard enough since if it is soft it could compact and give a false reading. Also, do not measure one point. Take an average of at least 3 or 4 points since this will give a better result statistically.

Test coupons are the ideal method for measuring the coating thickness, whether is it spraying or dipping, and can be kept as a physical record of the performance.

Wet film gauge

A final method is a wet film measurement technique that is very cost effective.

The technique uses a comb with different size patterns that is placed in the wet coating and the imprint left indicates the wet film thickness. Knowing the solids content of the material means that the material thickness can be calculated.

A wet film gauge is a low cost method for measuring coating thickness while the conformal coating is wet. Using the solids content in the material and the wet film thickness allows the dry film thickness to be estimated.

Need to know more about conformal coating thickness measurement?

Find out more from our article Conformal Coating Thickness Measurement: Wet, Dry & Optical Methods to get a more detailed review.

Or, contact us now and we can discuss how we can help you. Give us a call at (+44) 1226 249019 or email your inquiries at sales@schservices.com

What are the alternative materials to liquid conformal coatings?

April 11, 2017 alternative, Atomic layer deposition (ALD), Blog, conformal coating, Molecular vapour deposition, Parylene

There are several alternative coatings available to the traditional conformal coating materials.

These alternative coatings include:

Parylene and other Chemical Vapour Deposition (CVD) films
Fluorinated ultra-thin and thin film coatings
Molecular Vapour Deposition (MVD) coatings
Atomic Layer Deposition (ALD) coatings

They can provide extremely high protection to circuit boards if used correctly for the right product.

There are several new and old alternative coatings available to the traditional conformal coating materials. They include Parylene, fluorinated Nano-coatings, Molecular Vapour Deposition (MVD) and Atomic Layer Deposition (ALD) thin films.

Parylene (XY) Coatings

Parylene is the trade name for a variety of chemical vapor deposited poly(p-xylylene) polymers used as moisture and dielectric barriers.

Parylene is a conformal coating that is deposited as a gas in a vacuum chamber. It is a dry process compared to the standard “wet” liquid conformal coatings.

Find out more about our Parylene Coating Solutions or compare Parylene vs liquid conformal coatings in our knowledge hub.

Fluoropolymer (FC) Nano Coatings

Surface Modifiers are ultra thin nano coatings that are applied at less than a few microns in thickness. Liquid conformal coatings are applied in the range of 25-75um so they are considerably thicker in nature.

There are several variations in ultra thin conformal coatings out in the market now but two of the most popular types are liquid materials and partial vacuum deposition.

Read more about our full range of Fluoropolymer Nano Coatings.

Atomic Layer Deposition (ALD)

ALD belongs to the family of chemical vapor deposition methods (CVD).

It is a deposition process at a Nano-scale level within a vacuum chamber.
The deposition process forms ultra-thin films (atomic layers) with extremely reliable film thickness control.
This provides for highly conformal and dense films at extremely thin layers (1-100nm).

Molecular vapour deposition (MVD)

MVD belongs to both the families of chemical vapor deposition (CVD) and atomic layer deposition (ALD) methods.

Unlike traditional CVD and ALD flow systems the MVD reaction takes place in a chamber under static pressure resulting in extremely low chemical use.
The MVD process produces highly conformal thin film coatings, typically less than 100nm in thickness.
The coating provides excellent barrier properties and surface energy control.

Need to know more about alternative materials to the traditional liquid conformal coatings?

Contact us now and we can discuss how we can help you. Or, give us a call at (+44) 1226 249019 or email your inquiries at sales@schservices.com

Is There a Free Guide on Conformal Coating Defects?

April 6, 2017 Blog, conformal coating

SCH services Ltd provide an information section on conformal coating defects in their Defects Knowledge Hub.

This hub explains the most common defects and failure mechanisms, their root causes, and practical actions to prevent or correct them in production.

Conformal coating defects can undermine PCB protection, reduce insulation resistance, and cause costly rework or field failures. This hub explains the most common defects like de-wetting, de-lamination, corrosion and cob-webbing and details their causes and how to prevent them.

All this is linked to detailed technical articles and inspection guidance.

Need to know more about coating defects?

Contact us now and we can discuss how we can help you. Or, give us a call at (+44) 1226 249019 or email your inquiries at sales@schservices.com