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PCB Conformal Coating Services

With the advancement of technology, there are many techniques and methods used to make PCBA boards protected from hazardous conditions. Conformal coating is a technology that applies a protective layer of the polymer film to the PCBA, which is usually carried out after the components are soldered and tested. This coating protects the board from different environmental conditions like moisture, chemical reactions, dust particles, corrosion, and high-temperature conditions. The application range of this protective measure is very wide, such as communications, aviation, military and so on. This coating is applied on the 25 to 250 micrometers of the board.

For PCB conformal coating different methods are used such as spray, dispensing, dip coating, and brushing. Different materials such as acrylic, urethanes, parylene, and silicone are used for conformal coating. In some advanced levels, transparent conformal coating is applied since it is less weight and easily inspected.

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PCB Conformal Coating Offered by FS Technology

According to the chemical composition, we provide five types of conformal coating PCB services. You need to choose which coating to use according to the electronic project and application requirements. Here are the descriptions of the five types of conformal coatings:

Acrylic Conformal Coating

Acrylic Resins are done through the use of acrylic polymers which are solved in solvent and applied on the PCBA surface. Hand brush, spray, or dipping techniques are used to apply the acrylic conformal coating. Premium acrylic conformal coating with high viscosity and low odor. When the conformal coating process is over, it can be quickly cured to form a transparent film to protect the assembled PCBA board.

Advantages:

  • Multiple application methods allow for a quick process and easy cleaning or removal.
  • High flexibility allows easy adjustment of solution viscosity.
  • It has excellent adhesion and salt spray performance.
  • The repairing process is easy.
  • It has less shrinkage.
 

Disadvantages:

  • It has less resistant to chemicals
  • High VOC content, conformal coating process needs to be carried out in a confined space.
  • It is less resistant to abrasion
  • It is not used for harsh condition operations of boards
  • Not good for high-temperature conditions
 

Applicable field:

  • Vehicle electronics
  • 5G communication base station
  • Power supply and frequency conversion
  • Household appliances
  • LED and Lighting System

Polyurethane Conformal Coating

Polyurethane (Polyurethane Resin – UR) is a high-strength polymer that is flexible, insulating, stiff and chemically resistant. Electronic conformal coatings that use polyurethane as a raw material are known as polyurethane conformal coatings and are the best choice for protecting circuit boards from chemical abrasion and humidity. Polyurethane conformal coatings are very easy to apply but not easy to remove. For this technique, reparability is not used because it releases noxious gases.

Advantages:

  • High-quality chemical and moisture resistance reduce the risk of circuit board short circuits in extreme environments.
  • Second only to epoxy in terms of mechanical strength, it offers superior mechanical wear resistance compared to other conformal coatings.
  • It is a high temperature resistant conformal coating, the maximum service temperature is about 130 °C.
  • The coating is approximately 0.001” to 0.005” thick.
 

Disadvantages:

  • This is a solution that is not easy to remove. Forcible removal may result in unsightly board or damage to PCB components, and conformal coating remover is recommended.
  • Make sure the PCBA surface is clean before application, otherwise it may cause peeling.
 

Applicable field:

  • oil and gas industry
  • Agriculture
  • Household appliances
  • Household appliances
  • Extreme environments

Epoxy Conformal Coating

This type of conformal coating is the best option for harsh environmental conditions. Its application process is easy but the removal process is difficult and can damage the board. It comes in two elements thermosetting mixture. There is thermal or UV exposure to cure the one-unit compounds.

Advantages:

  • Epoxy coatings have high-strength adhesion and virtually no paint chipping after application.
  • In the absence of ester bonds, the aliphatic hydroxyl group contained in epoxy resin does not react with alkali to form a three-dimensional network structure, so that the epoxy conformal coating has excellent chemical properties and can operate under any harsh conditions.
 

Disadvantages

  • It needs a soldering iron to repair
  • Anti-acid effect is not good.
  • The aromatic ether bonds in the cured epoxy resin are easily degraded and broken under the action of ultraviolet light, which affects the effect of this conformal coating for outdoor applications.

Silicone Conformal Coating

Silicones conformal coating is the best option to save the board from high-temperature conditions and operate easily. The application of the process of this coating is easy and it provides less toxic conditions. This coating is one element component and protects the board from humidity, moisture, and abrasion.

Advantages:

  • Humidity resistant
  • Corrosion resistant
  • Good chemical resistant
 

Disadvantages

  • Removing process is difficult
  • There is a need of strong chemicals to remove it from the board

Paraxylylene Conformal Coating

This type of coating is applied on the board through the use of the chemical vapor deposition technique. Paraxylylene will be transformed into a gaseous phase after heat application. After that it is cold and is confined in the cylinder there is polymerized and converted into the film. Then this film is applied to the PCB board.

Advantages:

  • Operate well in high temperatures conditions.
  • It has high dielectric strength.
  • It is transparent and has no color
 

Disadvantages

  • It is not easy to remove
  • It needs certain instruments for chemical vapor deposition

Why Conformal Coating Services

The main purpose of conformal coating application is to protect the components existing on the board from environmental conditions. If conformal coating is applied accurately in result it will protect your board from rusting for a long duration. Some modern conformal coatings are applied to minimize the whiskers creation and also stop the flow of current between the adjacent component connected in circuits.

The conformal coating has been poured that helps moisture existing in the board to come out but safe boards from contamination. Here are some reasons explained that make effective use of this coating technique on board.

  • The conformal coating reduces the environmental stress application of PCBA.
  • It minimizes the bad operation of the board caused by the hazard environmental conditions.
  • It increases the dielectric strength among the conductors.
  • It creates a hindrance for contaminants to reach the board surface.
  • It reduces the chances of degradation in the operation of the board due to environmental hazards.
  • It protects the complete assembly of the board from chemical and corrosion.
  • It is a less-weight process.
  • It reduces the use of complicated and sophisticated enclosing for boards.
  • It insulated the conductor to make connections to each other.

How to Apply Conformal Coating

Brushing

It is a very common technique for conformal coating application on the board. It looks simple process but needs an expert person to apply a coating to make sure accurate finishing and good quality of the coating. There is a need for a brush, a coating container, and a place where the coating has to apply. Dip the brush into the coating container and apply it on the board.

Spray coating

In this technique coating is applied through aerosols, batch spraying, selecting spraying

Aerosol: In aerosol, the spray gun is used. It is configured as a solvent-configured coating. Spraying aerosol in the spray is a less costly technique. Less cost, high speed, and quality of finish make this process better than brushing.

Batch Spraying: In this technique, a compressed air gun is used and provides a good finishing. In this method, there is the use of a spray gun, spray booth, and air compressor. Adjustment of accurate pressure level and material used must be considered. The coating viscosity must be in the proper configuration.

Selective Spray: This technique is used to spray a certain area. This coatings technique is not used for areas that have connections of connectors.

Dipping

It is an older technique in which boards are dipped in a container that has coating material. The factors that are monitored in this technique are immersion speed, coating dwell time, and the withdrawal speed of the board. During this method, solvent-based conformal coating such as acrylics and urethans are used.

Vapor Deposition

In this technique, the coating is deposited in a gas form on the board. It is a costly process that is used of medium and high-level production. It has 4 steps that are listed here

  • Parylene Vaporization
  • Pyrolysis
  • Coating Deposition
  • Cold Trap

Summarize

FS Technology is the most professional PCBA manufacturer in China, we provide all services from PCB manufacturing to PCB assembly. Circuit board conformal coating service is one of the protection measures we provide in PCBA manufacturing. In addition, we also provide a wide range of testing services and quality management policies. For prototype assembly projects, we will provide free conformal coating for your circuit boards, if you are interested in our service items, please contact our sales by mail.

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