The evolution of conformal coatings for protection of PCBs and electronics has accelerated over the past few years. One development in particular has increased in popularity due to a promising array of advantages over its predecessors. These are LED Curable Coatings.

A partial list of existing technologies for conformal coatings would include:

• acrylics (both solvent and water-borne)
• solvent-borne polyurethanes
• silicone-based polymers
• synthetic rubber (solvent-borne)
• Parylene technology
• UV-curable acrylated urethanes (arc and microwave bulb source)

and most recently . . .

LED curable conformal coatings are showing promise in applications involving white goods and automobiles where high volume throughput combined with low energy and maintenance requirements can be paramount. In addition, new developments and chemistries have been able to minimize or eliminate some of the shortcomings of LED technology that limited its use in the past.

LED Curing Advantages/Limitations

The method of curing conformal coatings using LED light sources has a number of potential advantages but has also been accompanied by certain limitations in the past.

Advantages of LED curing include single, defined wavelength curing with: 

• consistent and repeatable cure
• lower energy requirements likely
• little or no hazardous wavelengths generated
• less heat generation
• longer bulb life and lower maintenance costs

Past limitations:

• limited choice of coatings and photoinitiators
• difficult to cure on thicker coatings such as conformal coatings for PCBs
• lower energy transmission (Lights must remain very close to surface for cure.)

A New Approach Yields Results

Chase Corporation polymer chemists have taken advantage of recent advances in photo-initiator technology and combined it with their nearly five decades of experience in conformal coating development. Their efforts and expertise have resulted in a number of new additions to the industry standard-bearing HumiSeal® line of conformal coatings and ancillary materials for protection of PCBs and electronics.

The latest addition to emerge from these efforts is HumiSeal UVA300LV. This LED curable conformal coating exhibits all the advantages related to LED curable materials as well as a number specifically designed for the demands of PCB protection.

• tack-free cure under LED UV light at 385 or 395nm
• low viscosity for film coater selective application
• secondary moisture cure for unexposed areas
• superior flexibility, chemical and moisture resistance
• fluoresce under UV light for inspection

LED curable coatings are suitable for nearly all conventional conformal coatings applications. Their lower energy requirements (estimated at 30% to 70%), minimal maintenance requirements, and short cycle times make them especially valuable in certain areas including:

• automotive PCBs due to their high volumes and energy requirements
• white goods such as refrigerators, washers, and dryers
• HVAC control boards
• electronic vehicle applications including power and safety controls and autonomous driving devices

UVA300LV is particularly well suited to the high throughput requirements seen in many automotive PCB applications where the properties of short cycle times, limited energy requirements, and lower frequency maintenance have been shown to be of great value. In addition, UVA300LV was designed with superior flexibility when compared to many traditional UV curable coatings. This leads to outstanding performance in many thermal and mechanical cycling and shock tests found within the automotive industry. 

As a supplier of all major forms and chemistries of conformal coatings, Chase Corporation and HumiSeal® can help you with an unbiased approach to evaluating your application and process. We’ll show you how to maximize efficiency, minimize cost, and improve product reliability. Our outstanding manufacturing and technical support groups can provide your organization with reliable global supply, unmatched quality, and superior technical

Please contact us today to discuss your application.