Five Reasons Why Conformal Coating Dipping can be One of the Most Effective Production Processes

Dipping a circuit board in coating can be highly effective. Here are five reasons why:

1. You can dip many boards at once. It can be the fastest conformal coating process of all the methods.
2. It is an extremely simple process. Hang the circuits, press a button and the boards are coated.
3. The process is very repeatable. Once set up the conformal coating thickness will be constant with very few process controls.
4. The conformal coating penetrates underneath components. This gives complete coverage.
5. The boards are coated both sides simultaneously. This halves the process time.

For further information click conformal coating dipping

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How to Select a Conformal Coating Process – The Holistic Approach

Choosing a conformal coating process is a complicated and involved process usually balancing a number of trade-offs and compromises.

This is because of three major parts of the complete process that can offer different options and create difficult choices.

These parts are:

1. The Conformal Coating Material Requirements
2. The Application Method Selected
3. The Circuit Board Design

When you consider these three points you have to balance them to create the best compromise solution that suits your requirements.

This is the Holistic Approach to conformal coating.

What is capillary flow in conformal coating and why does it occur?

Capillary / Scavenging on a printed circuit board where the coating has run away from an area around a component.

Capillary flow (also known as scavenging) in conformal coating is where the conformal coating pulls or runs away from certain areas of a PCB to more favourable sectors due to a combination of effects. This can leave a patchy finish on the surface of the board.

Factors that influence the capillary effect during processing include:

1. low viscosity of the conformal coating
2. an abnormally high amount of coating applied
3. a low surface energy of substrate
4. the high surface tension of the conformal coating.

For further information Click capillary conformal coating failure mechanism technical bulletin

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How to verify the conformal coating thickness on a printed circuit board in production for a dip coating system

When using a conformal coating dipping system it is important to know that the dry film conformal coating thickness is correct on the circuit board. Ultimately, the conformal coating will only be protective if applied at the right thickness so control of the process is crucial.

First, when we are coating PCBs we must assume that the variables for the conformal coating dip coating process are set up correctly for the PCB. That is that

1. The viscosity of the conformal coating is correct
2. The withdrawal speed of the dip system is correct
3. The temperature of the conformal coating is stable

These three parameters ultimately control the final thickness of the conformal coating on the circuit. Change one of the these and you can change significantly the conformal coating thickness.

Once this is set up and everything is in order we now want to monitor the coating thickness.

There are two options:

Option one: Measure the circuit board directly.

This can be done with a micrometer or a conformal coating eddy current system such as a Positector. However, this assumes that there is enough room for the probe or micrometer on the circuit board and (ii) there is metal in the PCB at the point of measurement for the Positector. Using this system after the coating is cured hard enough to test gives excellent readings

If this is not the case there is an alternative solution.

Option 2: Measure a test coupon

If the conformal coating thickness is correct on a circuit board when qualifying the process then it is possible to dip a test coupon to measure the equivalent coating thickness. This then allows you to use a test coupon at the start of the day’s production process to confirm everything is in order and no parameters have changed.

The process is the same as with measuring the circuit board. Dip the coupon. Dry it sufficient to measure the coating thickness and verify that the process is stable and there is no significant variation.

This is an easy method that is reliable. It also backs up your viscosity control measurements for your conformal coating and ensures your conformal coating dip process is in control.

Click Conformal Coating Thickness Measurement for further information.

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Can you use a moisture cure silicone conformal coating in a dipping machine?

Conformal Coating Dip System with PCBs hung ready to be coated

The answer is yes. It is done regularly and we have dip coating systems filled with moisture sensitive silicone materials that function perfectly.

The key is the way the conformal coating and the process are set up. Follow these steps to ensure your silicone dip conformal coating process is successful.

1. The coating may skin on the surface. Remove this whenever it occurs.
2. Use a catch tray in the weir of the dip tank. When the congealed coating drops into the catch tray the lumps will be caught.
3. Apply a moisture-free gas across the surface of the tank. This inhibits the moisture in air prematurely curing the coating.
4. Minimise the pumping of the coating. Turn the speed down to a minimum and only pump the coating when in use. turn off the pump there are long periods of no coating.
5. Apply proprietary thinners over the top of the coating during long periods of shut down

Contact us now to discuss your conformal coating dipping process and how we can help you.

Or, contact us here at +44 1226 249019 or email sales@schservices.com

Want to reduce your outsourcing costs of your conformal coating process or check just what it will cost to subcontract?

Conformal Coating Services FREE TRIAL

We guarantee to offer the lowest price solutions on a like for like basis for our subcontract coating services through our North America, Europe and Asia facilities.

How can we say guarantee this?

• We are experts in what we do! that means you get the best prices
• We provide conformal coating services at the source to the customer where we can
• This means we benefit from lower costs in our facilities which we can pass on as savings
• We have the full range of conformal coating processes and materials to offer so the customer gets the right application method and not a process which is isn’t fit for purpose.

This helps SCH provide the lowest cost solution without compromise to the customer.

FREE TRIAL

Let us prove to you we can coat your printed circuit boards and save you money.

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Links of Interest

Conformal Coating Parylene Services

Why Use Parylene?

Parylene Equipment

Parylene Removal

Global Subcontract Conformal Coating Services

SCH Technologies provide Global subcontract liquid Conformal Coating and Parylene Coating Service Solutions across North America, Europe, and Asia.

We are the number one complete conformal coating solution supplier within these markets. Our aim is to provide the same level of conformal coating service for application of all types of coatings wherever the customer is in the world without compromise.

This allows our group to work with customers to offer the best level of service when qualifying or coating products without concern about where the printed circuit boards (PCBs) may eventually finish up being manufactured.

In short

• We are conformal coating solution providers in North America, Europe, and Asia.
• We apply Parylene, Conformal Coating and RFI Shielding Paints using all manner of the standard methods
• We aim to provide the same level of service wherever we process your circuit boards in the world

Check out our conformal coating and parylene service pages here.

Or, contact us here at +44 1226 249019 or email sales@schservices.com

Ten reasons to use a Dip Coating System to apply conformal coating

1. It is the fastest and most cost-effective conformal coating application technique compared to other methods such as robotic selective coating, batch spray coating and brush coating
2. Dip Coating is one of the simplest processes for operators to use. Once set up the operation is generally very basic with minimal interaction from the operator.
3. It is one of the most efficient methods for application of conformal coatings and there is no over spray or very little material wastage
4. The process is excellent for all volume production whether large, medium or small.
5. The process of dipping a circuit boards into a conformal coating material contained in a tank ensures complete coverage, including underneath components and around difficult large 3D boards
6. The machines are very low technology based, so require very little skill in maintaining and servicing. They also tend to be the most reliable systems, providing very little downtime.
7. It is extremely easy to control the thickness of the conformal coating using a dip coating method.
8. The systems can have in-built drying and curing so the PCBs can be completed processed in one solution
9. You can coat PCBs in a vertical, horizontal or off-angle orientation to provide the most efficient dip coating process
10. The dip coating system can use practically any conformal coating in it, as long as the set up is correct and process controls are put in place.

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Conformal Coating Dip System with PCBs hung ready to be coated

Dip coating is the simplest and highest volume conformal coating process to be used. If printed circuit boards are designed for dip coating the huge savings in money, time and effort can be made. For help on design rules for dipping contact us direct.

For further information on Conformal Coating Dip Coating CLICK

• Conformal Coating Dip Systems (Inline)
• Conformal Coating Dip Systems (Batch)
• Conformal Coating Dip Systems (Bench)
• Conformal Coating Dip Systems FAQs

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What is the maximum height of components on the PCBs for a standard Conformal Coating AOI system?

This can be critical so important to know due to the length of the machine required and the imaging technology used in the conformal coating AOI. Camera slightly to the side. Hidden areas behind the components are now shown clearly. The first question to ask is are the PCBs 3D in nature or are very flat? This helps determine whether we use camera or parallax free scanning technology? Parallax is defined as a displacement or difference in the apparent position of an object viewed along two different lines of sight, and is measured by the angle or semi-angle of inclination between those two lines. How this relates to conformal coating AOI is that with a fixed camera or a standard scanner the camera is at a fixed point and the circuit board with its 3D components may have “shadows” where the camera cannot see down the side of the components. This can be seen in the two photos below. Take a look at our Conformal coating AOI Parallax link here to understand the issues more. Click For further information on Conformal Coating AOI Systems from SCH Technologies. Or, contact us here at +44 1226 249019 or email sales@schservices.com

NEW Technical Bulletin: Setting Up a Conformal Coating Production Line

The set up of a turnkey conformal coating production line or facility, whether it is a batch or inline process, has many similar characteristics.

Whether the coating application is based around a high volume selective coating robot, a batch dip coating system or a spray booth, the process requirements tend to be the same.

This bulletin reviews the potential needs of the facility, including the process controls, environmental needs and health and safety issues and provides some starting points for a new facility.

Click Setting Up a Conformal Coating Production Line Technical Bulletin for further information of Contact Us directly.