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.

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What are the main uses of Molecular vapor deposition (MVD) in protecting components?

Molecular vapor deposition (MVD) is a combined Atomic Layer Deposition (ALD) and Chemical Vapour Deposition (CVD) process that was developed to improve the protective performance properties of the individual ALD and CVD processes.

The MVD process provides protective thin films to many industries including:

  • MEMS (Microelectromechanical systems)
  • Semiconductors
  • Industrial Inkjet Heads
  • Display Technology
  • Advanced Packaging
  • Data Storage Industry
  • Biomedical
  • Genome Sequencing
  • µfluidics

How is the MVD coating process used in different industries?

The MVD process provides low temperature vapor deposition of coatings with many different properties in many sectors.

Consider the examples below where an MVD coating has been used to provide the appropriate film properties:

Surface Energy Control

  • Anti-stiction
  • Hydrophobic
  • Hydrophilic
  • Oleophobic
  • Oleophilic
  • Lubrication
  • Bio-functional layer

Device Protection / Package Sealing

  • Moisture barrier
  • Corrosion barrier
  • Chemical barrier
  • Gas/Oxygen barrier

Optical Films

  • Anti-reflection coatings

 Dielectric Films

  • Electrical insulation
  • Conformal films on high A/R

Adhesion

  • Adhesion promotion
  • Improved thermal stability
  • Improved mechanical durability

The MVD process offers great flexibility of processing thin films and it has now been considered for electronics protection.


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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?

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Three key points you should know about polyurethane conformal coatings when using them for protecting electronic circuit boards

A polyurethane (urethane for short and designated UR by IPC) conformal coating is part of the organic family of coating materials that also includes the acrylic and epoxy coatings.

Here are three key facts to consider when examining polyurethane conformal coatings:

  1. Most conformal coatings provide good humidity and moisture protection although some are slightly better in performance than others. UR type coatings are just as good on average as acrylic materials.
  2. A polyurethane coating has traditionally been used to protect electronic circuit boards against chemical attack due to their excellent chemical resistance. This protection allows electronic circuit boards to survive in highly aggressive environments and atmospheres such as the aerospace, military and industrial sectors. However, it does make repair a little more difficult as chemical resistance to a coating means more difficult to remove.
  3. Times are changing and whereas acrylic conformal coatings used to dominate 70-80% of the market, there is a shift in emphasis towards alternative materials due to higher specifications for protecting electronics. Many new conformal coatings (UV cure, two part thin film coatings) now comprise of urethane resin bases and are becoming more popular in high volume sectors such as automotive electronics. This is because the urethane resin lends itself to this type of technology more easily than the acrylic based resins.

Want to find out more about polyurethane conformal coating?

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What are conformal coating masking boots and why do they save you money?

Reusable conformal coating masking boots are a highly cost effective alternative masking material to masking tape.

Many components on printed circuit boards must remain uncoated when applying conformal coating. The purpose of masking is to prevent migration of the conformal coatings into components and keep out areas.

The use of masking tapes, dots and liquid latex can be an effective process in protecting components from ingress of conformal coating.

However, the application of the masking can be labour intensive, especially in higher volume applications.


The use of masking tapes, dots and liquid latex can be an effective process in protecting components from ingress of conformal coating.  However, the application of the masking materials can be labour intensive, especially in higher volume applications.

Custom made masking boots can offer a labour saving alternative in both the masking and de-masking stages of the coating process.

These completely reusable masking boots are applied over the components such as connectors, plugs and sockets that require protection from the conformal coating applied. They can be simple boots that fit over the top of a connector or a more sophisticated design such as the examples below.

They provide reliable protection for many different types of components for all the conformal coating application techniques that include batch and selective robotic spraying (as an alternative to difficult technical programming), vertical and horizontal dipping and vapour deposition of coatings such as Parylene.


Three reasons to switch from tape to reusable masking boots for conformal coating masking

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These simple reasons can save you up to 80% of your costs compared to masking tape:

  1. The masking application time is reduced. Masking boots can be 4-5 times quicker than masking tape.
  2. The de-masking (removal) time is reduced. Again it is much quicker to remove boots compared to masking tape.
  3. It is much less likely that the masking boot will leak and the component requires rework. Masking boots don’t leak and tapes can.

This means you can save a lot of money very quickly when switching to conformal coating masking boots compared to masking tapes.


Want to find out more about masking printed circuit boards before applying conformal coating?

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What are the different methods available for cleaning electronic circuit boards?

The topic of cleaning printed circuit board assemblies (PCBAs) effectively before application of conformal coating can be daunting. This is because the process of cleaning circuit boards can be difficult especially with so many variables to consider.

When considering cleaning the circuit you need to assess many factors including:

The board and component compatibility with the cleaning method
The ability of the cleaning method to remove the contamination effectively from the circuit
Any residues the cleaning process may leave behind that may be harmful to the circuit in the long term.
The reasons for cleaning the circuit (e.g. contamination removal, adhesion promotion etc.)?
After considering these factors you can compare with the processes available.


The main methods of cleaning printed circuit boards

The main methods of cleaning used in everyday electronics processing before conformal coating application can include:

  • Aqueous washing
  • Semi-aqueous washing
  • Solvent & chemical washing
  • Plasma surface cleaning

These processes can be mixed, the method can be varied but the fundamental concepts still apply.

However, whatever method you choose you still have to consider that the key to success in cleaning circuit boards is similar to the success made with conformal coating.

You need to match the cleaning process, the cleaning materials and the circuit board together.

If you do this then this will give you the best results for cleaning the circuit board assembly.


Want to find out more about cleaning?

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The science behind fluoropolymer coatings for protecting electronic circuit boards

Nano-coatings are being used regularly to protect printed circuit board assemblies.
This is because the material they are made of fluorinated polymers and these materials have very specialized properties that produce very different results to traditional conformal coatings.

So, what are the unique properties of a Nano-coating?

To understand the properties of a Nano-coating you have to understand what a fluoropolymer coating is made of.

Typically, the coating itself is comprised of fluorocarbons and characterised by carbon-fluorine bonds.
Since the coating is made of fluorocarbons then the film surface is not susceptible to Van der Waals forces (interfacial electrostatic bonds).

Therefore, the surface energy of the fluoropolymer coating is extremely low and hydrophobic (water repellent). It acts like Teflon on a frying pan.

This non-wetting of water on the circuit board is one of the many key properties making them so popular.

What other properties do Nano-coatings have that may help protect circuit boards?

For electronic circuit board assemblies there are several key properties that are being used.
These include being:
Hydrophobic: Being highly water repellent
Ultra-thin: Protection whilst being extremely thin
High moisture barrier: Low water vapor transmission rate provides excellent corrosion resistance
Chemically resistant: Having a high chemical resistance helps protect the circuits from chemical attack.
Good dielectrics: fluoropolymer coatings have high dielectric properties

However, to really understand the benefits you have to look at the key difference compared to a conventional conformal coating.

That is that no masking is required when applying the Nano-coating.


The key reason for using a Nano-coating in protecting electronics is that no masking is required whilst applying the coating to the printed circuit board.

In the image above the connector is coated completely in the Nano-coating. It was just dipped in the coating. The image shows the water is being repelled from the connector. However, electrically the connector works perfectly fine.

So, why is there no need to mask when using a Nano-coating?

First, consider a normal conformal coating is applied at typical thicknesses of 25um or more.

Also, the conformal coating is a high insulation material.

Therefore, at this thickness the conformal coating would electrically insulate components like connectors and it must not be applied to any part that needs electrical conductivity.

However, this is not a problem for a Nano-coating.

Since the Nano-coating can be applied at ultra-thin thicknesses (1-2um in thickness or less) without any protection performance reduction, then the extremely soft coating is easily removed or scratched away when the connectors are joined and the electrical circuit is easily made.

This key parameter of not requiring masking during Nano-coating application combined with the hydrophobic nature of the coating material makes the Nano-coatings highly effective in protecting electronic circuit boards at a very low cost per unit.


Want to find out more about Nano-coatings?

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