How does Parylene material differ from liquid conformal coatings and where can you buy it?

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Parylene is very different to typical liquid conformal coatings like acrylic, epoxy, silicone and polyurethane resin based materials.

When you buy Parylene it is a white powdered dimer.

This powder cannot be applied to circuit boards in its current state. The dimer requires specialist Parylene equipment that uses a Chemical Vapour Deposition (CVD) process. That is the dimer is placed inside the machine, a vacuum created and the dimer is then transformed to a gas vapour by being heated up.

This vapour created during the pyrolysis process can then be deposited on the printed circuit board as the Parylene coating.

This is very different to liquid conformal coatings. They start off as a “varnish” in a can or container and are applied to circuit boards by brushing, dipping or spraying. They then dry either naturally or artificially in some manner and the circuit board is now protected.


Where to buy Parylene

When purchasing Parylene it is important to find a source that provides a quality product. The purity of the coating is one of the key points in creating a successful Parylene process. Neglecting this fact can cause endless problems.

Remember that buying Parylene cheaply is easy. Buying cheap Parylene that is pure enough to protect the circuit board is another issue.

Thin film Partners can inform you of the right vendors who supply high-quality material and the pricing for each type. Then you can compare which vendor you would like to buy from.

This is a cost effective method to ensure you get the right Parylene coating at the right price.


Want to find out more about Parylene?

Contact us to discuss your needs and let us explain how we can help you.

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Why is it harder to mask and de-mask Parylene on a circuit board assembly compared to traditional liquid conformal coatings?

There are four key reasons why Parylene masking and de-masking is more difficult compared to liquid conformal coatings.

These are:

  1. Parylene is a vapour. When you are masking against a gas rather than a liquid then there is more of a challenge. So you need to provide a much better barrier with the masking process compared to the liquid coatings.
  2. Parylene is immersion. Most liquid conformal coatings are sprayed and so the capillary is less compared to immersion in a limitless supply of material.
  3. Stripping Parylene is hard. It is much harder to remove unwanted Parylene material on components that should not have been coated. Parylene is chemically inert (therefore harder to strip off or remove) and more difficult to see (no UV trace in most Parylene coatings). Mistakes can be more costly.
  4. The Parylene can bond more to the masking materials. When the Parylene is deposited on the masking materials and circuit board it can bind the two together and it can take significant effort and care to remove the masking materials without damaging the board or the Parylene coating integrity.

Need to find out more?

Click Parylene coating to protect electronic circuit boards to find out further information or contact us directly and we can help you.

If you are new to Nexus and our work on conformal coatings then a good place to go is our Start Here page or our free conformal coating eBook.

The ABCs of Parylene coating for electronic circuit boards

NEXUSParylene is a conformal coating that can be applied to electronic circuit board assemblies that is deposited as a gas in a vacuum chamber.

It is a completely different process to the normal liquid conformal coatings that are applied by alternative methods such as dip, brush and spray.

This difference means Parylene offer advantages and disadvantages in comparison.

For Parylene coating and electronics here are six key areas to consider.

These are:

Click on each link to find out more Parylene, the process and its properties.


Need to find out more?

Click Parylene conformal coating for electronics for further information or contact us directly and we can help you.

If you are new to Nexus and our work on conformal coatings then a good place to go is our Start Here page or our free conformal coating eBook.

Why use Parylene to protect printed circuit boards?

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Parylene is a conformal coating film that is applied using a specialised vapour deposition application process.

This means it is very different to all of the other liquid conformal coatings available on the market.


Three reasons why Parylene is better than traditional liquid conformal coatings

The fact that the Parylene film is deposited onto circuit boards in a vacuum leads to many unique advantages.

Here are three key reasons to use Parylene:

  1. The Parylene coating is completely conformal to the surface of the Printed Circuit Board (PCB) or product. The coating has a uniform thickness and is pinhole free. Therefore, components with sharp edges, points, flat surfaces, crevices or exposed internal surfaces are coated uniformly without voids.
  2. Parylene coating provides an excellent barrier that exhibits a very low permeability to moisture and gases compared to traditional liquid conformal coatings. This means that circuit boards coated in Parylene generally are more “waterproof” than the same circuits coated in a liquid conformal coating.
  3. Parylene has excellent electrical properties compared to normal conformal coatings. These include low dielectric constant and loss with good high-frequency properties, good dielectric strength, and high bulk and surface resistance.

Need to find out more?

Go directly to our Parylene section in Nexus  or contact us directly and we can help you.

If you are new to Nexus and our work on conformal coatings then a good place to go is our Start Here page or our free conformal coating eBook.

What is Parylene?

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

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

nexusphoto1Although Parylene is a conformal coating it is different compared to the standard “wet” liquid conformal coatings in that it is deposited as a gas in a vacuum chamber and it is a dry process. Image courtesy of Plasma Rugged Solutions

This method of chemical vapour deposition (CVD) and the Parylene dimer material itself give Parylene unique properties compared to other traditional conformal coatings.

For Parylene there are five key areas that Nexus can help with.

These are:


Need to find out more?

For further information on Parylene then contact us directly or go to our Parylene section in Nexus. See how we can help you.

If you are new to Nexus and our work on conformal coatings then a good place to go is our Start Here page or our free conformal coating eBook.

 

How do you remove Parylene completely from a printed circuit board?  

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

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

This method and the material itself give Parylene unique material properties that give it a lot of advantages compared to other traditional conformal coatings.

However, these unique properties also make it an extremely difficult material to remove.

Why is Parylene difficult to remove?

Compared to typical liquid conformal coatings like acrylics and polyurethanes that more easily dissolve in mildly aggressive solvents then Parylene is much tougher to remove.

The reasons are many why but a key point is that the Parylene coating itself is chemically inert. It has a 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.

So, chemical removal is almost impossible.

This leaves another well know method for Parylene removal that is mechanical abrasion.

Mechanical abrasion of a coating can be done crudely by scraping off the Parylene with a knife or tool. Or, removal can be done with a media blast system that gradually erodes the Parylene coating away.

However, mechanical abrasion is a time consuming process and is highly skilled. Any wrong action could result in irreparable damage.

Further, mechanical abrasion tends to be a localised repair and removal technique. The concept of completely removing all of the Parylene of a circuit by mechanical abrasion is considered almost impossible unless a ridiculous amount of time and effort is injected into the process.

Therefore, a specialist method is required to remove Parylene completely from a whole circuit board.

A new method for completely stripping Parylene from a PCBA

Due to new research two processes have been developed for completely removing Parylene coating from the surface of a circuit.

They are:

  • A method for <15um thickness of Parylene coating on the board
  • A method for >15um thickness of Parylene coating on the board

Removal with <15um thickness of Parylene coating on the circuit

When the Parylene coating is under 15um then the removal from the whole circuit is a relatively simple process.

To successfully remove the Parylene a technique has been developed involving plasma etching.

The plasma-etch process uses a proprietary blend of gasses, and a custom system to mechanically etch off the Parylene. This specially designed alchemy of gasses specifically attacks Parylene rather than the solder mask.

The technique successfully removes the Parylene from all over the board.

Also, the etching process is quick relative to the other mechanical methods. Typically, the circuit can be completely etched of Parylene in under an hour.

Further, the process is safe. It does almost no harm to the circuit and is one of the safest methods for complete removal of Parylene.

Removal with >15um thickness of Parylene coating on the circuit

When the Parylene coating is greater than 15um then the removal from the whole circuit is a little more complex. In fact, it becomes a two-stage process.

First, you can use the plasma etch treatment to loosen the Parylene from the surface of the circuit. Normally the Parylene is bonded well to the surface and this loosening allows for a second stage process.

In the second stage a media blaster like the SWARM system can be used to remove the coating. Since the coating has been loosened it does tend to come off much easier and quicker.

That said it is still a little slow and costs are higher. But, it still can be removed more easily.


Need to find out more?

For further information on Parylene removal then contact us directly and we can help you.

If you are new to Nexus and our work on conformal coatings then a good place to go is our Start Here page or our free conformal coating eBook.

 

Things you should know about Parylene

What is Parylene?

Parylene is a conformal coating that is deposited as a gas in a vacuum chamber.

It is a completely different process to the liquid conformal coatings and its properties offer advantages and disadvantages in comparison.

Parylene is a dry process compared to the standard “wet” liquid conformal coatings.

Since Parylene is deposited as a gas its thickness is almost uniform across the whole circuit board.

 

The ABCs of Parylene

Parylene is an organic polymer conformal coating that is deposited as a gas in a vacuum chamber.

Therefore, the Parylene application process is a completely different process to the liquid conformal coatings.

This gives Parylene unique properties that are not possible with the typical liquid conformal coatings normally used in electronics protection.

 

Five key facts about Parylene

  1. Parylene is the trade name for a variety of poly(p-xylylene) polymers
  2. It is a conformal coating that is deposited as a gas in a vacuum chamber. This is different to liquid conformal coatings.
  3. The Parylene film is created via a controlled Chemical Vapor Deposition (CVD) process.
  4. It is a dry process compared to the standard “wet” liquid conformal coatings.
  5. This process makes Parylene a highly effective moisture and dielectric barrier that outperforms most liquid conformal coatings.

 

Three important points you should know about Parylene

  1. Parylene has unique properties that are not possible with the liquid conformal coatings.
  2. Parylene is a conformal coating that is deposited as a gas in a vacuum chamber.
  3. This is different to liquid conformal coatings that can be brushed, dipped or sprayed.