Don’t blush when you talk about conformal coating!

Conformal coating blushing low resBy definition, blushing (also known as blooming) is when the conformal coating appears to be blotchy, milky, or cloudy.

Some problems of blushing include
:

  • Surface tackiness or greasiness
  • Incomplete cure
  • Poor adhesion
  • Poor adhesion on over-coating
  • Coating discoloration over time
  • Poor gloss retention (matte finish)

Environmental conditions could be a factor that influences blushing in conformal coating.

This can be caused by the absorption of carbon dioxide and water into the conformal coating film.

To find out more, click Conformal Coating Defects: Blushing

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.

Do you know the difference between the conformal material and process standards?

There are international, national, national trade bodies, and internal company standards for conformal coating processing and inspection thus providing a guideline for users.

Conformal coating processing and inspection standards cover two areas, namely:

  • Material manufacture
  • Production process

These can be further broken down by type.

Material manufacture

  • MIL-I-460558C
  • Underwriter laboratories
  • IPC-CC830B
  • IEC 61086-1ed 2.0

Production process

  • IPC A610
  • IPC HDBK 830

Read more about these standards on Conformal Coating Standards and Specifications 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.

What’s the difference between a surface modifier and a conformal coating?

Surface Modifiers is an ultra-thin coating that is applied at a few microns in thickness.

In contrast, liquid conformal coatings are typically applied in the range of 25-75 um thus being thicker in nature.

Two of the most popular types of these ultra-thin coatings are:

  • Liquid materials which dry onto the substrate
  • Materials which are applied in a partial vacuum

The change in energy that a surface modifier creates when applied to a circuit board makes it harder for liquids like water and oiled to wet the surface and cause damage.

Read more at What is a Surface Modifier Coating?

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.

Can you name all of the physical properties of a conformal coating?

Conformal coatings come with multiple physical characteristics that are dependent on the chemistry of the coating.

These properties can be subdivided into three sections, namely liquid properties, process properties, and dry state properties, which can be further subdivided into various individual properties that a conformal coating is composed of.

Liquid Properties

  • Flash point
  • Storage lifetime
  • Appearance and color
  • Density
  • Solids content
  • Viscosity

Process Properties

  • Wetting
  • Capillary
  • Viscosity
  • Wet film thickness
  • Surface tension
  • Pot life
  • Drying and curing

Dry State Properties

  • Edge loss
  • Refractive index
  • Glass transition temperature
  • Coefficient of thermal expansion
  • Flammability
  • Flexibility
  • Abrasion resistance
  • Hydrolysis stability
  • Permeability
  • Chemical compatibility and resistance
  • Corrosion resistance
  • Fungus resistance
  • UV stability
  • Outgassing
  • Thermal stability
  • Thermal shock

Read more at Conformal COating Physical Properties: 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.

Whats the best brush technique for applying conformal coating?

Brush coating cropped really smallBy definition, brush coating is the application of a conformal coating with the use of a brush to “paint” on the coating to the circuit board. However, this is misleading.

The correct technique is to flow the coating. The material should not be brushed on like a paint. The coating should be loaded on to the brush and flowed onto the circuit. The areas covered by the operator are only those that require the coating.

The requirements for brushing conformal coating are basic and low-cost. These items are:

  • A quality brush
  • Containers to store the conformal coating
  • A suitable workstation

Remember that lighting conditions make a huge difference when applying coatings. UV light can also help an operator in completing the task.

At low-volume, the brush coating process can be highly cost-effective.

However, there are key variables that influence the quality of the process which include:

  • Operator skill
  • Viscosity of the coating
  • Complexity and size of the board
  • Conformal coating material type

The speed of the coating process depends on how much area of the board needs to be coating as well as the complexity of the board’s design.

Read more at Conformal Coating Application Methods: Brushing

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 are the five main advantages of the conformal coating dip process?

PCBs dipped in DS101 close upFor years, dip coating has been known as the traditional method in applying comformal coating onto circuit boards. It is in this process wherein the circuit is dipped into a conformal coating liquid.

In its simplest form, a board can be dipped manually into a container of conformal coating. However, dip coating is normally done with equipment especially if medium and high volume processing is required.

There are several key variables that control the quality of the coating including

  • Viscosity of the conformal coating
  • Speed of immersion of the circuit board into the conformal coating
  • Dwell time of the circuit board in the conformal coating
  • Withdrawal speed of the board from the conformal coating
  • Critical process controls

There are also five main advantages to the dip coating process. These are:

  • Dipping is a high-speed conformal coating process
  • It is highly repeatable
  • Multiple circuit boards can be coated with dipping
  • Both sides can be coated simultaneously
  • The process requires less operator skill

Read more at Conformal Coating Application Methods: Dipping

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.

Why blisters in your conformal coating can be painful!

Blistered PCB 2Blistering is the formation of circular-shaped bubbles of the coating film held away from the substrate which can be the beginning of the conformal coating deliminating.

Some factors that cause blistering in conformal coating include:

  • Cleanliness of the surface
  • Compatibility of the conformal coating and the surface
  • Permeability to moisture
  • Degree of coating cure

Using techniques such as the following can help minimize blistering:

  • Cleaning the surface of the board
  • Matching the conformal coating to the solder resist
  • Choosing a less permeable conformal coating
  • Reducing the thickness of the coating
  • Lowering the cure temperature
  • Applying a primer to the surface of the board

Read more at Conformal Coating Defects: Blistering

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.