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

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Diamond MT, a conformal coating and Parylene coating service provider in the USA, found they saved more than 60% of their current masking 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.

Diamond MT saved more than 60% of their current masking costs by switching to the SCH range of conformal coating masking boots.

Diamond MT saved more than 60% of their current masking costs by switching to the SCH range of conformal coating masking boots.

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.

This meant what started as a simple trial led to a huge saving to Diamond MT as a partner with SCH.

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?

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Dip coating is a traditional conformal coating application method that has been used to conformal coat circuit boards for a very long time.

The process in its simplest form is as follows:

  • The printed circuit board (PCB) is dipped into a tank of conformal coating liquid.
  • 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).

What equipment may you need for dipping circuit boards in conformal coating?

A simple process is a board dipped by hand into a container of conformal coating. This can give some reasonable results.

However, normally dip coating equipment is used. This is especially true if medium and high volume processing is required.

The reason for using dipping machines is because the process has variables that are critical to film integrity and they are controlled by the machine 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.

A simple process is a board dipped by hand into a container of conformal coating. This can give some reasonable results. However, normally dip coating equipment is used. This is especially true if medium and high volume processing is required.
A simple process is a board dipped by hand into a container of conformal coating. This can give some reasonable results. However, normally dip coating equipment is used. This is especially true if medium and high volume processing is required.

 

How cost effective is the dip process for conformal coating?

The conformal coating 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.

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?

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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.
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. Most conformal coatings lend themselves well to the technique.

Key factors that

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.

A highly viscous coating will be harder to apply correctly than a lower viscosity material.

What factors control the quality of conformal coating finish with brushing?

Key variables that influence the quality of the process include:

  • Operator skill
  • Quality of the brush
  • Viscosity of the coating
  • The coating environment
  • Complexity and size of the board
  • Conformal coating material type

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?

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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.

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.
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.
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?

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?

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.
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.

Fluoropolymer (FC) coatings

Surface Modifiers are ultra thin 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.

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.

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?

Blog, conformal coating

Nexus, the independent conformal coating information site, provide an information section on conformal coating defects in their free online Ebook.

According to Nexus, problems in conformal coating can be broken down into two areas.

  • Problems relating to conformal coating process
  • Problems relating to product reliability

In their troubleshooting section they focus on troubleshooting the problems associated with conformal coating processing and production.

You can download the PDF guide Solving conformal coating problems in the application process now.

Need to know more about conformal coating defects?

Contact us now and we can discuss how we can help you.

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Why does cleaning improve the adhesion of the conformal coating?

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In general it is important that conformal coatings have good adhesion in order to be effective. However, there is no single theory that describes the property of adhesion for conformal coatings.

There are three basic mechanisms for conformal coatings that are known to help with good adhesion.

They are:

  1. Adsorption
  2. Chemical Bonding
  3. Mechanical Interlocking
There are three basic mechanisms for conformal coatings that are known to help with good adhesion. They are adsorption, chemical bonding and mechanical Interlocking
There are three basic mechanisms for conformal coatings that are known to help with good adhesion. They are adsorption, chemical bonding and mechanical Interlocking

Adsorption

This is where the molecules in the conformal coating wet or flow freely over the substrate and make intimate contact with the substrate. This forms interfacial (electrostatic) bonds with van-der-Waal forces.

Any contamination between the two will weaken the adsorption. Any de-wetting (prevention of wetting) will also hinder the adsorption.

Cleaning the surface of contamination will help with adsorption.

Chemical bonds

The bonds are formed at the interface between the conformal coating and the substrate.

Good bonding gives strong adhesion of the conformal coating to the substrate. If bonding cannot be achieved due to contamination then poor adhesion may result.

Cleaning the surface of contamination will help the chemical bonding process.

Mechanical interlocking

The conformal coating film penetrates the roughness on the substrate surface and is achieved once the coating dries.

If the surface is smooth then the mechanical bonding is less effective. If the surface can be cleaned, leaving a rough surface, then more effective bonding can be achieved.

Cleaning the surface of contamination will help.

Achieving the best conformal coating adhesion

Surface contamination can be critical when considering conformal coating and the process. If you can clean the contamination from the surface then the adhesion of the conformal coating should improve.

All three mechanisms do not have to occur to form good adhesion. Depending on the specific conformal coating system, substrate, and application method, different mechanisms could work.

However, good wetting or adsorption is normally required for good bonding.

So, if in doubt clean the surface of the substrate to achieve good conformal coating bonding.

Need to know more about conformal coating adhesion?

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

Are there design rules for applying conformal coatings?

Blog, Uncategorized

Conformal coating is not simply a consumable material. Unfortunately, for too many designers, conformal coating is simply a part number, to be applied to circuit boards.

However, this can be a major problem especially in the conformal coating production stage of the process.

There are guidelines in the IPC standards that may help with Design for Manufacture (DFM) principles. These are worth considering.

Unfortunately, there are no official design guidelines that will help directly with the application process and conformal coating.

Unfortunately, for too many designers, conformal coating is simply a part number, to be applied to circuit boards. However, this can be a major problem especially in the conformal coating production stage of the process.
Unfortunately, for too many designers, conformal coating is simply a part number, to be applied to circuit boards. However, this can be a major problem especially in the conformal coating production stage of the process.

Nexus Design Rules

Nexus, the independent conformal coating knowledge base, has developed both guidelines for conformal coating reliability and conformal coating process.

Their philosophy is that for companies embracing lean philosophies and applying conformal coatings, a failure to appreciate the subtleties of the application process can result in an uncoatable (at least as specified) assembly process.

They also state that if the rules are not followed, the resultant circuit board design can challenge even the most sophisticated conformal coating system and its operator to achieve the finish desired.

Nexus have design rules for both general processing and for specific application processes such as dipping, selective coating and batch spraying.

For further information visit conformal coating design rules to learn more.

Need to know more about conformal coating design rules?

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Do you need MiL spec qualification for your conformal coating?

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march 28 image

 

Normally, customers know if they require MIL-I-46058C qualification for their conformal coating. It normally is required if it is a military product.

However, caution should be shown when examining conformal coating datasheets that state MEET the requirements of MIL-I-46058C since the conformal coating will likely not be on the Qualified Product List (QPL).

What is the Qualified Product List (QPL)?

The Mil Standard for conformal coating has been inactive for new designs since November 1998. However, the standard is still widely used for independent certification of conformal coatings.

All companies tested to the MIL-I-46058C standard are listed on the QPL. It is still possible to register the coating on the list.

Conformal coatings listed on the QPL will have been through rigorous 3rd party testing to confirm they meet the standard. They are not self-certified.

So, if you require a conformal coating material that is Mil-spec approved then it will have to be on the QPL and it will have been independently tested.

Need to know more about Mil Standard conformal coatings?

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What is plasma cleaning?

Blog, Plasma, Plasma cleaning

Plasma cleaning is a process of using plasma energy to clean and modify the surface of a substrate like a circuit board assembly.

It is a highly effective surface cleaning and treatment process before application of conformal coatings and is gaining more popularity due its highly effective performance.

Plasma cleaning is a process of using plasma energy to clean and modify the surface of a substrate like a circuit board assembly. It is a highly effective surface cleaning and treatment process before application of conformal coatings and Parylene.
Plasma cleaning is a process of using plasma energy to clean and modify the surface of a substrate like a circuit board assembly. It is a highly effective surface cleaning and treatment process before application of conformal coatings and Parylene.

What is Plasma?

Plasma is the energy-rich gas state (also known as the fourth state of matter) that can be used to modify the surface of a product to improve its performance.

Plasma technology is based on a simple physical principle.

Matter changes its state when energy is supplied to it. Solids become liquid. Liquids become gas.

If additional energy is then fed into a gas by means of electrical discharge it eventually ionises and goes into the energy-rich plasma state, plasma is created.

This modification can be improving the adhesion of a conformal coating or change the surface characteristics of the board.

How is Plasma used for improving the performance of coatings with printed circuit boards?

For electronic circuit surfaces, plasma treatment can be used in two highly effective ways.

That is it can:

  • Clean the surface of the circuit board. The surface will be free of residues and 100% contamination free including release agents and additives.
  • Activate the surface of the circuit board assembly. This will allow easier bonding and better adhesion of conformal coatings.

These properties make it an interesting technique for improving the surface performance of an electronic circuit board.

In fact, plasma treatment can clean, activate or coat nearly all surfaces. These surfaces include plastics, metals, (e.g., aluminum), glass, recycled materials and composite materials.

This means the plasma process can be highly effective on many different products.

For electronic circuits, plasma treatment can be used in two highly effective ways. First, it can clean the surface of the circuit board. Second, it can activate the surface of the circuit board assembly to allow easier bonding and better adhesion of conformal coatings and materials like Parylene.

For electronic circuits, plasma treatment can be used in two highly effective ways. First, it can clean the surface of the circuit board. Second, it can activate the surface of the circuit board assembly to allow easier bonding and better adhesion of conformal coatings and materials like Parylene.

What are the typical plasma processes available for surface treatment?

There are traditionally three types of plasma treatment:

  1. Low-pressure plasma
  2. Corona treatment
  3. Atmospheric pressure plasma

Low-pressure plasma

These plasmas are generated in closed chambers in a vacuum (10-3 to 10-9 bar).

They can be used in conjunction with Chemical Vapor Deposition (CVD) coatings like Parylene before application.

Corona treatment

Corona treatment (corona process) is a physical process involving high voltage and is mainly used for treatment of films.

This is normally not suitable for electronic circuit boards.

How is the plasma applied to a circuit board to clean and activate the surface?

For materials like liquid conformal coatings then atmospheric pressure plasma is an excellent process for cleaning surfaces and improving adhesion and surface energy performance of circuit boards for conformal coatings.

Atmospheric plasma is generated under normal pressure. This means that low-pressure chambers are not required.

The plasma is created with clean and dry compressed air and does not require forming gases. It is possible to integrate plasma directly into manufacturing processes under normal pressure conditions.

Typical plasma components used for cleaning surfaces on circuits are:

  • Plasma jets (nozzles) to apply the plasma to the surface of the circuit board. They could be controlled by a robotic system.
  • The plasma generators that create the plasma to clean or supply the coatings as required. They provide output power and, in conjunction with complete pretreatment stations, assume various control functions.
  • The process monitoring that controls the nozzles, the movement of the system and the quality of the output.

These three parts form the plasma cleaning process.

For Chemical Vapor Deposition (CVD) coatings like Parylene then low-pressure plasma can be used in the chamber before application.

These plasmas are generated in closed chambers in a vacuum (10-3 to 10-9 bar).

Want to know more about plasma cleaning and conformal coating performance?

Contact us now to discuss what we can offer you in terms of cleaning fluids from our Surclean range of materials.

Give us a call at (+44) 1226 249019 or email your inquiries at sales@schservices.com

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