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

Blog, conformal coating

 

SCH

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:

  1. The board and component compatibility with the cleaning method
  2. The ability of the cleaning method to remove the contamination effectively from the circuit
  3. Any residues the cleaning process may leave behind that may be harmful to the circuit in the long term.
  4. 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

Blog, Fluoropolymer

SCH UK1

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.

SCH UK2

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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Five key facts about using fluoropolymer Nano-coatings for protecting printed circuit boards

Blog, Fluoropolymer

June15-3

  1. A Nano-coating is hydrophobic. It repels water from the surface of the circuit board and water will not wet the circuit.
  2. The Nano-coatings are extremely thin (<2um). They are very different to traditional conformal coatings.
  3. Nano-coatings do not require masking. The circuit board can be completely submerged in the liquid with no masking applied without damaging components.
  4. They have excellent chemical resistance due its fluorine bonds. The Nano-coatings are perfect to protect against chemical attack.
  5. Using a Nano-coating is a fast simple process. The coating can be dipped quickly, without masking, and the coating dries extremely fast.

Want to find out more about Nano-coatings?

Contact us to discuss your needs and let us explain how we can help you. Or, read more on Nano-coating technology for protecting circuit boards now.

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

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Three key reasons to use a Molecular Vapor Deposition (MVD) process to protect a circuit board instead of conformal coatings

Blog, Molecular vapour deposition

Molecular Vapour Deposition (MVD) is a new process introduced to the electronics coating market.

MVD is a hybrid coating technique using ALD (Atomic Layer Deposition) and CVD (Chemical Vapor Deposition) coating processes in combination.

The method uses multiple layers of ultra-thin coatings with differing properties to build a completely protective coating with a final hydrophobic Nano coating as a top layer.

MVD

Here are three key points that strongly suggest you should find out more about this coating:

  1. The physical and electric performance of the MVD coating is superior to other materials like conformal coatings and Parylene. Parameters such as Water Vapor Transmission Rate (WVTR), hydrophobicity, coating adhesion, dielectric strength and temperature performance (>250°C) are vastly improved when protecting circuit boards.
  2. The MVD coating does not require masking to protect sensitive components and electric connectivity in connectors is easily made even when coated. This is because the coating thickness of the MVD material is x10 less than that of Parylene.
  3. The cost of process is much lower than all other protective materials due to the fact that raw ingredients are low cost and no masking is required.

There are many other performance criteria that make this material a really interesting process that could change perceptions.

For further reading try the Nexus Blog articles

See how this coating could improve the performance of your circuits now.

Want to find out more about Molecular Vapor Deposition?

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

Blog, conformal coating

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”.

These three key areas were:

  1. Quality
  2. Turnaround time
  3. Price

They stated that,

“if you get these three key areas correct then you have succeeded.

Everyone will be happy and there are no more problems with conformal coating.”

(Source: Nexus).

However, within each of these areas, they outlined a lot of questions that should be asked to ensure you get it right.

Those points were examined in detail with some real insight into subcontract services.

If you are considering outsourcing your conformal coating then I can recommend reading the article now.

Want to find out more about subcontract conformal coating services?

To find out more click outsourcing your conformal coating project – The key points and read the article now.

Or, 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 help you.

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What is a fluoropolymer nano coating and how can it protect my circuit board?

alternative, Blog, Fluoropolymer

SCHUK1

A fluoropolymer Nano-coating is an ultra-thin film comprised of fluorocarbons and characterised by carbon-fluorine bonds.

Chemically inert, fluorocarbons are not susceptible to Van der Waals force. This means that films formed using these materials are non-stick (hydrophobic and water repellent) and friction reducing.

Also, due to the fluorine bonds, these Nano-coatings demonstrate a high level of chemical resistance to acids, bases and most solvents.

This makes them interesting materials for protecting electronic circuits. 

What properties of the Nano-coatings areused to protect circuit boards?

Fluoropolymer coatings have very specialised properties.

However, for electronics the main properties that are useful include:

  • Being highly hydrophobic (water repellent)
  • Having a high moisture barrier
  • Having a high chemical resistance
  • Having high dielectric properties
  • Providing high corrosion resistance
  • Providing good abrasion / wear resistance

These properties are excellent for protecting circuit board assemblies in harsh environments.

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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Do you need UL qualification for your conformal coating?

Blog, conformal coating

UL are the Underwriters Laboratories and are a global safety certification body for consumer electronics.

They are a 3rd Party test service. There is no self-certification available.

A qualification to UL can be used as a sign of quality control and testing independently of the coatings protective ability.

When do you need UL?

Sometimes it may be required that the conformal coating needs UL approval to be applied to a circuit board. It will depend on the market the electronics goes into.

UL approved coatings can be used on electronics in many diverse sectors such as the domestic home, industrial controls, telecommunications and aerospace.

In fact, in nearly all areas conformal coatings tend to be used for protection.

SCHUK_1

UL approved coatings can be requested in nearly all areas conformal coatings tend to be used for protection for electronics including domestic home, industrial controls, telecommunications and aerospace.

What standards are used from UL for conformal coatings?

For conformal coating, two parts of the UL standards are important.

These are:

  • UL 94: Standard for Safety of Flammability of Plastic Materials for Parts in Devices and Appliances testing.
  • UL 746E: Standard Polymeric Materials: Industrial Laminates, Filament Wound Tubing, Vulcanized Fiber and Materials Used in Printed-Wiring Boards

The two standards together control the quality of the conformal coating. They are discussed more in detail below.

UL 94

It is a plastic material flammability standard.

The standard classifies plastics according to how they burn in various orientations and thicknesses.

UL 94 measures conformal coating material’s tendency either to extinguish or to spread the flame once the test specimen has been ignited.

Classifications

For conformal coatings the test coupons are normally tested horizontally.

Tests are normally conducted on coupons of the minimum approved thickness with different types of laminate. The conformal coating thickness range also is normally specified.

The ratings are as follows:

  • V-2 burning stops within 30 seconds on a vertical specimen; drips of flaming particles are allowed.
  • V-1: burning stops within 30 seconds on a vertical specimen; drips of particles allowed as long as they are not inflamed.
  • V-0: burning stops within 10 seconds on a vertical specimen; drips of particles allowed as long as they are not inflamed.

Most conformal coatings aim to achieve V-0 status (top result).

UL 746E

UL 746E is the Standard Polymeric Materials: Industrial Laminates, Filament Wound Tubing, Vulcanized Fiber and Materials Used in Printed-Wiring Boards

UL 746E measures the ignition resistance of the conformal coating to electrical ignition sources.

The conformal coating material’s resistance to ignition and surface tracking characteristics is described in UL 746E.

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 optimise your process for you.

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