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Why does the solids content of my conformal coating matter for costing a printed circuit board for application?

The amount of solids content in a conformal coating is the amount of actual material available to be applied to the circuit board and that will protect the circuit board assembly.

The more solids you have the more circuit boards you can coat.

So, you want to have as much solids as possible per liter when you buy the material.


Caution –Check the conformal coating solids is at the right viscosity for application!

You also need to take care when comparing individual materials from different companies.

The differences in both solids content and viscosity can be striking and you can be wasting a lot of money on solvents that literally evaporate away.

The first stage in checking this is to determine the final solids content of the material that you will use in production. That is the correctly blended coating ready for application at the right viscosity.

Take the following example that is typical of conformal coatings sold commercially around the world.

Material X is 35% solids as sold.

Its viscosity is 190 cps approx. at this solids content.

However, to spray the coating it must be at 24 cps approx. So, the coating must be diluted by 50% with thinners to reach this viscosity.

This means material X is now 17.5% solids and a viscosity of 24 cps approx. This also means there is >80% of the material that evaporates away!


Check the market!

You cannot assume that all conformal coating materials are similar.

For example, SCH have a UL approved acrylic conformal coating that is 44% solids at 24 cps and ready to spray.

Comparing Material X (17.5%) and this particular material means that the higher solids coating has more than twice as much coverage power for the same liter of material.

If the coatings are similar in price at this viscosity then you need to buy at least 2x more of material X than the higher solids product to get the same coverage.

Quite a saving can be made if care is taken!


Want to find out more about coating coverage?

If you would like a spreadsheet that you can just punch the values in to calculate coating coverage and costs per PCB then contact us directly and we can send it through to you to help you.

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

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Requirements for setting up a conformal coating facility

The set up of a conformal coating production line regardless of the application method has many similar characteristics.

Any coating facility will need the basic requirements put in place that would be standard for any piece of electronic manufacturing process.

These include ESD systems, facilities for the machines, the environmental requirements and the normal Health & Safety (HSE) considerations.

Also, the conformal coating production line, whether it is an operator manually brush coating printed circuit boards (PCBs) or an inline robotic spray coating process is typically made up of several stages.

These stages are shown below:

Not all the stages are mandatory or may be required.  However, each should be considered on an individual basis.


Want to find out more about setting up a conformal coating facility?

Download our technical bulletin on setting up a conformal coating application process.

Or, contact us to discuss your needs and let us explain how we can help you.

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Five key facts about Parylene when protecting printed circuit board assemblies

  1. The Parylene conformal coating process is a very specialised vapour deposition application method using specialist vacuum chamber systems. This differs significantly to all of the other liquid conformal coatings available on the market that are applied by spraying, brushing and dipping.
  2. Parylene coating is completely conformal and uniform to the surface of the Printed Circuit Board (PCB) or product. It is also pinhole free. Therefore, components with sharp edges, points, flat surfaces, crevices or exposed internal surfaces are coated uniformly without voids.
  3. Parylene coating provides an excellent moisture and gas barrier due its very low permeability. This means that electronics circuit boards coated in Parylene generally are more “waterproof” than the same electronics coated in a liquid conformal coating.
  4. Parylene is unaffected by solvents (it has very high chemical resistance) and is very effective against salt attack.
  5. Parylene has excellent electrical properties. This includes having low dielectric constant and loss with good high-frequency properties, good dielectric strength, and high bulk and surface resistance.

Want to find out more about Parylene?

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

Or, read more on Parylene equipment and our Parylene subcontract services now.

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Nexus article on, “Outsourcing your conformal coating project – The key points”

Nexus

Nexus, the independent conformal coating resource, recently published an article on subcontracting your conformal coating services out to a third party.

I thought it would be useful to signpost people to this article and republish the points they raised since getting it right can be so critical in outsourcing.

Nexus identified that there are, “three key points to consider when choosing a subcontractor”.

Click here to read more about Nexus’ article on, “Outsourcing your conformal coating project – The key points”

Find out how we can help you with your conformal coating process now.

Contact us to discuss your needs and let us explain how we can optimize your process for you.

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How do I selective apply my conformal coating?

Selective application of conformal coating is this case is applying the conformal coating without using masking to shield components from ingress.

Technically using masking tapes, latex and boots is a selective process. But, we want to look at coating application without masking.

This leaves a couple of different options.

The first is brushing. This is a simple selective process that can be highly effective.

The second, and the more obvious option, is selective robot.

This process uses a small spray valve (there are many conformal coating spray valve types) that is attached to a robot that follows a set pattern applying the conformal coating selectively to the circuit board.

To read more about how to selective apply conformal coating, click here…

Find out how we can help you with your conformal coating process now.

Contact us to discuss your needs and let us explain how we can optimize your process for you.

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Are there design rules for the conformal coating dip application?

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There are design guidelines that can be used to help make conformal coating of circuit boards using the dip process a lot easier.

Having these specific design rules for dipping conformal coating can help save a lot of time, money and trouble on the production line.

Click to read more on about design rules for the conformal coating dip application

Find out how we can help you with your conformal coatings now.

Contact us to discuss your needs and let us explain how conformal coatings could work for you.

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What application methods are available for applying conformal coating?

What application methods are available for applying conformal coating?

Conformal coatings can be applied to printed circuit boards (PCB) in the production process environment in many alternative ways.

Listed below are the common methods of applying the conformal coating materials.

  • Brushing
  • Aerosol spray
  • Batch spray
  • Selective spray
  • Dipping
  • Vapour deposition

Click to read more on about application methods available for applying conformal coating

Find out how we can help you with your conformal coatings now.

Contact us to discuss your needs and let us explain how conformal coatings could work for you.

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What is a hydrophobic acrylic conformal coating?

There are several reasons for using a conformal coating or Parylene to protect a printed circuit board (PCB).

They include:

  • High insulation protection
  • High moisture and humidity protection
  • Chemical and temperature resistance
  • Ruggedisation
  • Improve dielectric properties
  • Barrier protection against particulates

However, one property that most liquid conformal coatings do not possess that is extremely useful to have is being water repellent or hydrophobic.

Click to read more about hydrophobic acrylic conformal coatings.

Find out how we can help you with your hydrophobic acrylic conformal coatings now.

Contact us to discuss your needs and let us explain how our hydrophobic coatings could work for you.

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How do I spray coat my conformal coating?

Batch spraying is one of the widest used techniques used in low and medium volume conformal coating processing.

Whether you are using a compressed air spray gun or an aerosol can, the conformal coating is sprayed across the whole of the circuit board.

It can produce a high quality coating finish that gives the best protection due to good edge coverage.

However, it is not a selective process. All parts are coated on the circuit board.

Therefore, masking may be required to protect components that must not be coated.

Click to read on How do I spray coat my conformal coating

Find out how we can help you with your conformal coatings now.

Contact us to discuss your needs and let us explain how hydrophobic coatings could work for you.

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Why use a conformal coating to protect your electronic circuit board assembly?

conformal-coating-markets-and-uses

A conformal coating protects the circuit board during its lifetime of use

A conformal coating is a protective non conductive dielectric layer that is applied onto the printed circuit board assembly surface to protect the electronic assembly during its working life.

The coating protects from damage due to contamination, salt spray, moisture, fungus, dust and corrosion caused by harsh or extreme environments.

The coating is usually used on electronic products that are exposed to adverse environments where heat, chemicals and / or moisture are prevalent.

Conformal coating also can prevent damage from rough handling, installation, reduction of mechanical and thermal stress.

It can prolong the life of the product during its operation and at the same time, it can help to increase the dielectric strength between conductors enabling the design of the PCB to be more compact and small.

Finally, it also acts to protect circuitry and components from abrasion and solvents.


Want to know more?

For help on conformal coatings then talk to SCH directly.

We can help with all coating requirements and offer free advice to help you.

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Check out our website at www.conformalcoating.co.uk or 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.