Conformal Coating Spray: The Ultimate FAQ Guide

This guide covers everything you need to know about a conformal coating spray system.

Therefore, before you opt for spraying technology for your conformal coating process, read this guide.

What is the Spray Application of Conformal Coating?

Spray application of the conformal coating is executed by depositing pressurized coating material through a nozzle.

You can use an aerosol container or a spray gun connected to a tank with the desired coating material.

Technological advancements have led to the development of faster automated spray processes with higher accuracy levels.

Applying conformal coatings by spraying is effectively used on short and medium board production cycles.

You can easily apply coatings via spraying when handling the repair or rework of circuit boards on your work-bench.

Similarly, you can set up special chambers from which you can handle spray applications for a reasonably sized number of boards.

The coverage achieved through spray application is remarkable primarily for edged components.

Consequently, you find reduced cases of slump when employing spraying as a coating procedure for your PCB.

Can you achieve a Quality Finish with a Spray Application of Conformal Coating?

A successful coating procedure is dependent on a variety of factors.

These factors include cleaning the board surface before application and selecting a coating material with good adhesion to the board.

The execution of the application process will determine the quality.

An individual’s skills will significantly determine the final coating quality.

You expect an experienced hand to achieve better quality than a novice.

The person applying a coating via spray will determine the coating’s depth and the uniformity of the surface.

Nonetheless, the application of a spray coating will be hindered by an uneasy hand that will result in inconsistencies.

Spray conformal coating PCB

What are the Limitations of Spray Conformal Coating?

While the spray method provides benefits such as requiring little investment and being easy to apply, several difficulties are observed. Some are described thus:

• Since the spray method is carried out by hand, it is slow and time-consuming.

The coating cycle time associated with spray application pales in comparison with automated processes.

• Applying a coating by spray method on an intricate board design can be challenging. Areas to be coated that are in between large board features, for example, can be a problem.
• Furthermore, board areas not to be coated require masking to shield them from the conformal coating spray.

Masking consumes time and is incredibly difficult when the areas are scattered all over the board.

• Achieving the right penetration with a spray application of the coating is difficult.

The problem is compounded when you have to apply the coating underneath components.

What Coating Materials can be Applied by Spray Application?

You can employ coatings of various material compositions through spraying.

Spraying is a method of deposition favorable with the liquid matter.

Most coating materials are solvent-based and therefore, using the spray method is advantageous.

Common conformal coating materials used with this method include:

· Acrylic Resin

These resins are easy to apply with good dielectric properties and resistance to abrasion.

You also achieve remarkable elasticity quality and face little difficulty in removing them.

· Epoxy Resin

Epoxy coatings have high resistance quality against humidity, scratching, and chemicals.

· Silicone Resin

With this coating type, you find it highly flexible and reliable in different temperature conditions.

Furthermore, the resistance quality against chemicals and salty water is impressive.

· Polyurethane Resin

You find polyurethane resins provide good resistance to chemicals, humidity, and scratching.

Why are Conformal Coating Sprays Essential?

Conformal coating sprays when applied form a thin and transparent layer of acrylic over the printed circuit board.

The nature of this coating is such that it doesn’t affect the properties of the shielded features.

These coating sprays play essential roles such as:

Conformal coating sprays shield metallic board features from moisture that could cause corrosion and result in loss of conductivity.

Board features such as electrical components are protected from particles such as dust that could clog their connectors, affecting their functionality.

Otherwise, these components would be faulty and offer services for a fraction of their intended lifespan.

Another significance of conformal coating spray is their reduction of the wear and tear process of board features.

Board features, when left exposed to the elements of the environment, will deteriorate over time.

Conformal coating sprays are also used for their aesthetic effect on the circuit board features.

They keep these features with their original shine making them seem new always.

What are the Considerations Before Employing a Spray Conformal Coating?

While spraying conformal coatings to circuit boards is considered cost-effective, you also need to consider the following factors:

• The number of printed circuit boards you are to work on. Using spray application will be effective when the numbers are low.

However, employing spray application for a large volume of boards will dilute the cost-effectiveness.

• The coating cycle time is the amount of time spent to complete a coating application process on a PCB.

The coating cycle time is particularly important when time limits have been attached to a batch.

As such, you will need to determine whether the cycle time in employing the spray method is convenient.

• The circuit board design is vital in determining the coating application procedure. Intricate board designs with high components density are unfavorable for spray coating. Additionally, you find spray application for areas underneath components is complicated, and its use in such cases is unjustified.
• Spray coating is mostly done manually by skilled operators to achieve higher efficiency levels.

Before carrying out a spray application for PCBs, you need to determine the labor requirements to execute an undertaking successfully.

If the cost of labor is high, other options can be considered.

• Any application process is accompanied by the use of equipment or devices to help execute the job.

Spray application encompasses the use of spray guns and aerosol cans whose availability you need to establish before commissioning.

How do you Conduct Conformal Coating Spraying?

Like any other coating application process, you have to clean the PCB surface before applying the coating.

Cleaning rids the surface of contaminants, which could be caught under the coating to instigate corrosion.

Furthermore, you have to dry the surface for proper adhesion of the coating.

The coating materials are combined with solvents to attain the right viscosity for effective spraying to conduct a spray application.

When a coating material is made too thick, you will find it very difficult to dispense it as a spray.

When the coating material is made too thin, its adherence to the PCB surface would be weak.

You can apply coatings by spraying through automated mechanisms such as selective coating or manually using spray guns or aerosol cans.

You find manual applications are relatively cheaper and affordable than automated methods.

However, they are limited to small board volumes and conditions such as rework while being prone to inefficiencies from human limitations.

For the efficient application of conformal coating via manual spray method, the application angle should be 45 degrees.

The angle of application is that at which the spray spout is relative to the board.

Additionally, the application should be applied on a ninety-degree board rotation and forward and backward.

 Conformal coating spray

What is the Difference Between Aerosol and Non-aerosol Spray Method?

The aerosol spray method involves the use of pressurized air to vaporize the coating material.

Consequently, employing this approach requires you to have equipment that can atomize the conformal coating, such as aerosol.

When the can top is squeezed, compressed air can push the coating out in a mist via a small outlet.

You find the aerosol spray method’s application outcome to be a thin, uniform, and consistent coating finish.

Achieving the desired thickness requires successive spray operations.

In the non-aerosol spray method, the coating material is not delivered as a mist by using compressed air.

Instead, you find this method employs a nozzle fan that initiates the material’s spread onto the board surface.

You achieve increased coating thickness with the non-aerosol method.

Manual non-aerosol coating application is done using a spray gun.

While automation is also possible, you require the use of specialized equipment to effectively apply the coating via a needle release.

Is Masking necessary when Applying Conformal Coating Spray?

Masking is the process of shielding areas that don’t require coating on a PCB from the inadvertent application.

Masking is especially useful when employing conformal coating spray.

Aerosol spray method, for instance, disseminates the coating as a mist over the board surface.

You find controlling the spread of the mist when an application is restricted is difficult.

Consequently, to prevent unintended coverage, masking is referred to as a solution.

The application of masking in conformal coating spray is minimized with automated spraying.

The spray coverage can be regulated by programming the valve opening and the distance of application.

Also important is the board design, which can be furnished to locate no-coat areas along a single edge.

When is an Automated Conformal Coating Spray application preferred?

Automatic conformal coating spray

Automated spray application is made possible by the use of programmable robots.

Using robots allows you to achieve much higher precision levels regarding thickness and surface uniformity.

Furthermore, you can carry out multiple repeated processes with impressive consistency and without the effects of fatigue typical with human operators.

You find an automated coating using spray application significant with large production volumes of PCBs.

Since setting up a computerized system is costly, the process’s effectiveness can only be observed with higher work volumes.

You find the coating cycle time associated with robots is much shorter, allowing higher throughput.

What are the limitations associated with automated conformal spray coating?

Automated spray as a coating application procedure is considered an efficient and productive approach to large volume circuit board productions.

However, the use of an automated spray method can be limited in a few ways:

• An automated spray process’s effective performance begins with the identification of the ‘coat’ and ‘no coat’ areas.

The information obtained is after that programmed to guide the robots as they conduct the application process.

However, some ‘no coat’ areas, such as connectors and component pads, are challenging to program.

• You will find the robot-controlled spray tips to be fragile and easily damaged when obstructed.

Consider a misaligned circuit board component in the path of travel of a robot-controlled tip.

Carrying out a repair or replacement on them is expensive and time-consuming, which affects productivity.

A remedy is to have sensors on the spray-tip that initiate a forced stop on obstruction, which adds to the cost.

• Programming board details to be executed by the robotic controlled equipment enhances process effectiveness.

However, you find programming to be a highly skilled activity that requires significant investment in equipment and labor.

• The automated spray method minimizes the need to mask the entire ‘no coat’ areas of the circuit board.

Nevertheless, some board areas are difficult to effectively program into the system requiring masking.

• The automated spray coating application has little room for errors.

Consequently, the occurrence of such would result in a massive failure rate.

The fast process and repeatability compound the failure rate.

For example, an erroneous input where a ‘no coat’ area is designated for coating application.

What Features of Conformal Coating Spray?

The successful application of coating by spray method requires the process to be conducted in a space with good aeration.

Also critical are personal protective equipment such as gas masks to prevent inhalation of the fumes that could be toxic.

Other notable features used are:

• Spray booths that have the added benefit of extracting the fumes and filtering them before emission.

Using a spray booth supports application with a spray gun without difficulty resulting in a consistent coating finish.

Furthermore, you can carry out a multiple coating process with the same results in a spray booth.

• Furthermore, you can use an ultraviolet source to illuminate the circuit board to guide the application process.

Also available is a turntable that can be controlled either manually or automatically to rotate the board through.

Both these features enhance the quality of the coating process by reducing the effects of shadowing.

• A curing chamber can be provided to hasten the drying process of the coating.

In this chamber, the circuit board is contained to prevent the flow of coating that could affect its evenness.

The air is sucked out, eliminating any particulate presence while the fumes are filtered of toxins.

• An inspection cubicle is used to determine the success and quality of the coating procedure.

Since coatings are generally clear, black light of the ultraviolet kind is employed.

Such an inspection reveals areas with an inadequate coating that require to be redone.

What are there Features of Silicon Conformal Coating Spray?

You find several features and benefits attached to the use of silicone conformal coating spray.

Some of these features are discussed below:

• Silicone coating spray can tolerate a high working temperature of up to 200 ^o Consequently, you can use such coatings in applications with elevated temperature values.
• Silicone coating can be administered by automated means such as selective coating. You also find this coating can fluoresce when subjected under ultraviolet light.
• The resistance levels achieved against salty water and humidity are impressive for silicone coating spray, with their electrical properties unaffected.
• Silicone coatings spray applied are not prone to molds’ growth, and ultraviolet radiation doesn’t alter its properties.
• After applying a silicone coating via spray method, removing them to carry out rework or repair is not difficult.
• You achieve high circuit penetration for your PCB with silicone coatings as very little oxygen can penetrate it.

What are the Applications of Conformal Coating Spray?

Conformal coating sprays of a different kind are employed over PCB surfaces to protect the board features from environmental elements.

The protected features include solder joints, bare traces, component leads, and other metallic parts likely to be corroded.

With conformal coating sprays, you achieve an extended lifespan for your board and guarantee decent performance levels.

Typical applications for conformal coating spray are:

• Automotive and aerospace applications such as control units.
• Military and marine technology such as in the electrical system of submarines.
• Lighting applications, for instance, LED lighting.
• Industrial application that encompasses a wide variety of usages like home appliances.
• In the telecommunication industry, such as mobile phones.

In short, spraying technology is an important technique in the PCB conformal coating.

Contact us today for all your PCB fabrication and conformal coating needs.