04/03/2010, Irvine, California

 

Circuit Board Protection Without Compromise: Why Proper Materials Selection and Compatibility are Essential for Conformal Coating Success

With numerous potential applications and a plethora of formulations from which to choose, it is often difficult to know how to select the best conformal coating for the job. Understanding the application and end use are critical in the decision but even that isn’t all you need to know. You may select a silicone-based conformal coating because you have very high and very low temperature performance requirements.

Or, if your requirements dictate more speed in your manufacturing process a UV formulation may be the answer. Those are great starting points, but how will the conformal coating interact with other materials or residues on the board? Can your materials supplier even provide this data?

Like all electronics processes, the material’s characteristics are not the only measure of success. An evaluation of equipment compatibility, processability, potential materials interactions and the overall manufacturing objective all play key roles in choosing the right conformal coating. It is essential that your materials supplier understands your process, the material’s performance and business objectives that you hope to achieve. It’s also important to have a vast array of materials from which to choose, so that the process is optimized through selection of the most suitable material for the job. Define what the end use requirement will be. If the product will operate in a high temperature environment -- i.e. greater than 150°C -- silicone-based materials are the clear choice for maximum reliability. Henkel’s Loctite 5293 and Loctite 5296 both deliver the robust performance of a silicone with two different cure options depending on preference. Loctite 5293 is a UV moisture cure system and allows for faster production speeds, whereas Loctite 5296 is UV activated with a thermal secondary cure. Both are dispensable and compatible with most major automated dispensing systems. If the end use environment ranges from -40°C up to 150°C, the choices broaden and selections can include an epoxy, urethane or acrylic-based solution. To narrow the field, analysis of solvent requirements and/or chemical resistance needs are the next issue to be addressed. The manufacturing and materials supplier should continue drilling down until all details of conformal coating selection have been addressed.

It bears mentioning that, because of legislative and environmental requirements, there has been a big push to eliminate solvents when possible. Conscious of this industry driver, Henkel set out to develop robust, solvent-free conformal coating materials. The result? Two products, Hysol PC40-UM and Hysol PC40-UT, conceived and formulated by Henkel deliver outstanding, solvent-free conformal coating performance. These organic, non-silicone coatings offer the protection necessary for some of today’s most well-known electronics products. As the names imply, one formulation is a UV moisture cure and one formulation cures with a UV gel followed by thermal exposure so that customers can select the method that best suits their manufacturing requirement. If, however, your process dictates that solvents are still in the mix, Henkel has engineered a solvent-based system that is toluene-free. A one-component solvent-based acrylic, Hysol PC62 offers all of the quick drying benefits of traditional toluene-based systems in a more operator-friendly toluene-free alternative.

Finally and perhaps most importantly, is having a level of confidence that the conformal coating will perform in your production environment exactly as it has been advertised. As the pioneer in materials cross-compatibility analysis and the development of tested and proven material sets, Henkel can provide data on conformal coating compatibility with a variety of other materials. It would be quite a set back to have gone through a detailed evaluation of conformal coating materials, select one and then discover that the board has failed because your conformal coating and solder paste flux affect each other adversely. With Henkel, you have the peace of mind of knowing that our conformal coatings have already been evaluated against many other materials and that you will have tested and verified compatible materials – day 1.

Today’s electronics environments are tough. Make sure your conformal coating and your materials supplier are up to the task. Select Henkel and you’ll be sure to have the best of both worlds. For more information on our full line of conformal coatings, log onto www.henkel.com/electronics or call the company’s headquarters at 949-789-2500.