The many Physical Properties that are important in a conformal coating when dry

Coated board Close UpIt is in the dry state when the conformal coating reaches its full potential for its physical properties.

The important physical properties of the coating include:

  • Abrasion resistance
  • Chemical compatibility
  • Chemical resistance
  • Coefficient of thermal expansion
  • Corrosion resistance
  • Edge loss
  • Film thickness
  • Flammability
  • Flexibility
  • Fungus resistance
  • Glass transition temperature
  • Hydrolysis stability
  • Out gassing
  • Permeability
  • Refractive index
  • Temperature gradient
  • Thermal shock
  • Thermal stability
  • UV stability

Read more at Conformal Coating Physical Properties: Dry State

Who is Nexus?

Nexus brings together the accumulated knowledge of a group of conformal coating and electronics material dispensing consultants who provide a unique service, focused on helping electronics manufacturing clients improve their conformal coating and electronics materials processes.

Nexus operate across North America, Europe and Asia and can provide a unique perspective to the rapidly growing conformal coating and electronics materials industry. Expertise is held in liquid and parylene coating, capital equipment sales and specifications and material, equipment and process specification, troubleshooting and training.

Production Key stages in Conformal Coating: Masking

Sealing a circuit ready for dip conformal coating using masking tape and latexIn conformal coating, some components and printed circuit board locations must remain uncoated due to the nature of the coating.

The purpose of masking is to prevent the application of conformal coating on components that need to be clear.

There are several masking techniques using various masking materials including:

  • Masking Dots and Tapes
  • Liquid Latex
  • Masking Boots

In general, making a circuit board for conformal coating can be a straightforward process. However, the skills required need to be learnt.

Read more at Conformal Coating Processing: Masking

Who is Nexus?

Nexus brings together the accumulated knowledge of a group of conformal coating and electronics material dispensing consultants who provide a unique service, focused on helping electronics manufacturing clients improve their conformal coating and electronics materials processes.

Nexus operate across North America, Europe and Asia and can provide a unique perspective to the rapidly growing conformal coating and electronics materials industry. Expertise is held in liquid and parylene coating, capital equipment sales and specifications and material, equipment and process specification, troubleshooting and training.

Troubleshooting your conformal coating process: Capillary flow

Capillary flow on a circuit board due to scavengingIn conformal coating, capillary flow is where the coating pulls or runs away from areas of a PCB thus leaving a patchy finish.

Factors that causes the capillary effect are

  • Low viscosity
  • Volume of coating
  • Substrate cleanliness
  • High surface tension

However, it is possible to reduce these effects by

  • Increasing the viscosity
  • Reducing the volume of coating
  • Cleaning the board properly
  • Using a solvent-based material
  • Heating the circuit board

Read more at Conformal Coating Defects: Capillary Flow

Who is Nexus?

Nexus brings together the accumulated knowledge of a group of conformal coating and electronics material dispensing consultants who provide a unique service, focused on helping electronics manufacturing clients improve their conformal coating and electronics materials processes.

Nexus operate across North America, Europe and Asia and can provide a unique perspective to the rapidly growing conformal coating and electronics materials industry. Expertise is held in liquid and parylene coating, capital equipment sales and specifications and material, equipment and process specification, troubleshooting and training.

Alternative materials to traditional liquid conformal coatings

Surface modified by a  fluoropolymer conformal coatingAside from traditional liquid coatings, Parylene and fluorochemical materials serve as potential coating alternatives.

Parylene is used in a dry process wherein the coating is deposited in a gas vacuum chamber.

On the other hand, fluoropolymer surface modifiers are ultra thin coatings that are applied at a few microns in thickness.

Two of the most popular types of this ultra thin conformal coatings are

  • liquid materials that dry onto the substrate
  • materials which are applied in a partial vacuum deposition

Read more on Alternative Coatings: Overview

Who is Nexus?

Nexus brings together the accumulated knowledge of a group of conformal coating and electronics material dispensing consultants who provide a unique service, focused on helping electronics manufacturing clients improve their conformal coating and electronics materials processes.

Nexus operate across North America, Europe and Asia and can provide a unique perspective to the rapidly growing conformal coating and electronics materials industry. Expertise is held in liquid and parylene coating, capital equipment sales and specifications and material, equipment and process specification, troubleshooting and training.

A Closer Look at Conformal Coating Selective Spraying

 

Robotic Selective conformal coated PCBSelective spraying is one of the most efficient conformal coating techniques. It involves the use of a robotic program that accurately targets circuit board areas that needs to be coated. It also avoids the components that don’t need coating.

A wide range of specialist spray guns are used to achieve this kind of efficiency and selectivity. It creates a precise spray pattern during the conformal coating process.

The Basics:

  • Selective spraying can be used for all conformal coatings.
  • A specialized robotic machine is required for the application of selective coating.
  • The initial investment is high but the ROI is good as it can handle high volume of coating.
  • Operating the robotic system requires extensive skill and training.
  • It eliminates the need for masking since the spraying is targeted.
  • It is a medium to high volume process.

Variables to consider in selective spraying conformal coating:

  • The operator’s skill and extensive training
  • Quality of selective spray robotic equipment
  • Compatibility of valve technologies
  • Perfect blending of conformal coating with the right viscosity
  • Compatibility of circuit board design
  • Temperature and humidity in the location of the robotic equipment

There are advantages and disadvantages to using selective spraying. Some of the benefits include the elimination of masking, high speed coating, and high volume processing. The downside of this technique is that it requires huge capital cost and high level of skill and expertise to operate.

Read more at Conformal Coating Application Methods: Selective Spraying

Who is Nexus?

Nexus brings together the accumulated knowledge of a group of conformal coating and electronics material dispensing consultants who provide a unique service, focused on helping electronics manufacturing clients improve their conformal coating and electronics materials processes.

Nexus operate across North America, Europe and Asia and can provide a unique perspective to the rapidly growing conformal coating and electronics materials industry. Expertise is held in liquid and parylene coating, capital equipment sales and specifications and material, equipment and process specification, troubleshooting and training.

 

What You Need to Know About The Parylene Vapour Deposition Method

 

Paratronix Parylene ProcessVapour Deposition is a unique conformal coating technique as it is a dry process unlike other methods that are liquid-based.

The coating is applied on circuit boards through a vacuum chamber where the components are coated in batches. Parylene is a material applied during the deposition process at room temperature.

All parts that shouldn’t be coated ought to be masked prior to the vapour deposition.

The Basics:

  • It requires a specialist system that is designed for vacuum application.
  • The set up may cost significant investment initially
  • The process can handle low and medium volumes
  • Vapour deposition application is relatively simple but the initial process development can be complex
  • Coating thickness is an important parameter and calculations should be exact.
  • It is one of the most expensive coating processes but produces the best finish.

Variables to consider in vapour deposition conformal coating:

  • The operator’s skill and extensive training
  • Knowledge in preparation particularly in handling Parylene material
  • Cleanliness of the surface
  • Masking requirements
  • Circuit board design

Just like other conformal coating application process, there are advantages and disadvantages to using vapour deposition.

Some of the benefits include excellent protection due to very low permeability, high solvent and salt protection, and 100% clarity as Parylene can coat optical components. On the flipside, the capital costs are high, preparation can be challenging, and it requires the highest masking level.

Read more at Conformal Coating Application Methods: Vapour Deposition

Who is Nexus?

Nexus brings together the accumulated knowledge of a group of conformal coating and electronics material dispensing consultants who provide a unique service, focused on helping electronics manufacturing clients improve their conformal coating and electronics materials processes.

Nexus operate across North America, Europe and Asia and can provide a unique perspective to the rapidly growing conformal coating and electronics materials industry. Expertise is held in liquid and parylene coating, capital equipment sales and specifications and material, equipment and process specification, troubleshooting and training.

 

Troubleshooting Conformal Coating Contamination

 

Contamination on the circuit board on top of the conformal coatingContamination happens when debris is trapped or found on the conformal coating of the printed circuit board. This can affect the reliability of the board over time.

Origin of Contamination:

Contamination can occur during the following situations:

  • Pre-production stage
  • Processing stage (during application)
  • Drying or curing stage
  • During the lifetime of the product

Preventing Contamination:

Contamination during the conformal coating process can be avoided by:

  • Improving cleanliness prior to production.
  • Having an efficient cleaning process prior to conformal coating.
  • Ensuring a safe and effective process after the coating.

Read more at Conformal Coating Defects: Contamination

Who is Nexus?

Nexus brings together the accumulated knowledge of a group of conformal coating and electronics material dispensing consultants who provide a unique service, focused on helping electronics manufacturing clients improve their conformal coating and electronics materials processes.

Nexus operate across North America, Europe and Asia and can provide a unique perspective to the rapidly growing conformal coating and electronics materials industry. Expertise is held in liquid and parylene coating, capital equipment sales and specifications and material, equipment and process specification, troubleshooting and training.