Conformal coatings rose to prominence in protection of printed circuit boards (PCBs) about five decades ago. Through their use, early PCB failures due to dust and dirt, liquids, and humidity contamination were greatly reduced or eliminated. This in turn allowed for the longer warranties and improved reliability we see today. Early conformal coatings, many of which are still in use today, were comprised of polymers dissolved in various solvents such as MEK, toluene, or xylene.
An approximate evolution of conformal coating chemistries could be viewed as
- solvent-borne acrylics and polyurethanes
- waterborne acrylics
- synthetic rubber coatings
- UV-curable acrylated urethanes
- LED UV-curable acrylated urethanes
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. These industries have also begun to place emphasis on utilizing GREEN, environmentally responsible materials wherever appropriate. LED conformal coatings can play a role in this green evolution.
What Makes LED Curables Green?
Image: PCB passing through a UV light cure conveyor belt
The method of curing conformal coatings using LED light sources has the potential to be a green alternative to solvent-borne as well as traditional UV-cured coatings.
Compared to solvent-borne coatings, LED curables
- are 100% solids
- are lower in volume for packaging and shipping
- are lower in energy requirements versus thermal drying ovens
- have little or no VOC content
Compared to traditional full-spectrum arc or microwave UV curing, LED curing results in
- lower energy requirements
- less frequent maintenance and replacement of light sources
- fewer hazardous wavelengths -- no UVC required
- no hazardous ozone
New UV40 LED
Chase Corporation and HumiSeal, a leader in the field of conformal coatings and electronics protection, have introduced a new LED-curable version of the industry favorite UV40 coating. This LED-curable conformal coating exhibits all the advantages related to LED-curable materials as well as a number of benefits 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
- fluoresces under UV light for inspection
Potential Applications
LED-curable coatings are suitable for nearly all conventional conformal coatings applications. Their lower energy requirements compared to arc or microwave systems 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
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 will show you how to maximize efficiency, minimize cost, while improving product reliability. Our team of manufacturing and technical support specialists can provide your organization with reliable global supply, unmatched quality, all combined with superior technical support.
