Conformal Coating

Electronic Coating Technologies applies conformal coating to printed circuit boards with select coat robotic dispensing systems. These selective coating systems allow us to create a repeatable coating thickness, and precise coverage area which helps eliminate some of the high cost masking steps typically associated with conformal coating. This repeatability lets us maintain our quick lead times, as well as offer unprecedented quality control.

Conformal coatings are a dielectric material used to protect electronic circuitry against potential failure causing situations such as thermal extremes, chemicals, dust, salt fog, and moisture. Conformal coatings also help to protect the electronic assemblies from physical damage which can be caused during handling and installation.

One characteristic of conformal coatings which has helped proper electronic design to where it is today is the coating’s ability to increase dielectric strength between conductors. This feature has allowed electronic assemblies to become more compact by allowing closer spacing of the conductive pathways. The coatings also help to minimize dendrite growth which can cause electrical short circuits.

Conformal Coating Types:

The below conformal coating types are currently able to be sprayed at Electronic Coating Technologies:

Acrylic Resins (AR) Strengths & Weaknesses

Acrylic conformal coatings are easy to apply, and within minutes dry to the touch at room temperature. Acrylic resins do not shrink upon cure, and have a long working pot life. They have good fungus resistance as well as good resistance to humidity. Acrylic resins do dissolve easily in solvents, but this trait also leads to them being easy to rework. They do soften more quickly when compared to other chemistries when exposed to elevated temperatures, and also have a poor resistance to abrasion.

Epoxy Resins (ER) Strengths & Weaknesses

Epoxy conformal coatings are typically available as two-part materials which begin to polymerize upon mixing. They can also be available as single a component material which can be cured with either elevated thermal exposure or with exposure to Ultraviolet (UV) light. These materials have good chemical, and abrasion resistance, with reasonable resistance to humidity. They are normally difficult to remove making rework difficult.

Polyurethane Resins (UR) Strengths & Weaknesses

Polyurethane conformal coatings are one of the most resilient types of conformal coating. They are available as one or two-part materials. Polyurethanes offer very good solvent, corrosion and fungus resistance, and also offer a high dielectric strength.

Silicone Resins (SR) Strengths & Weaknesses

Silicone conformal coatings are available in different forms, including heat-curing, moisture curing, and UV curing. They have a high resistance to corrosion, and solvents. They are also well-suited for high temperature applications. Silicones tend to be very flexible, but offer little adhesion, and abrasion resistance.

Type AR

Acrylic Resin

0.03 – 0.13 mm (0.00118 – 0.00512 in)

Type ER

Epoxy Resin

0.03 – 0.13 mm (0.00118 – 0.00512 in)

Type UR

Urethane Resin

0.03 – 0.13 mm (0.00118 – 0.00512 in)

Type SR

Silicone Resin

0.05 – 0.21 mm (0.00197 – 0.00827 in)

Type XY

Parylene Resin

0.01 – 0.05 mm (0.000394 – 0.00197 in)

IPC J-STD-001D Conformal Coating thickness requirements

Technical Data Sheets