Testing two component (2K) conformal coating materials

Louise Smyth

The performance requirements of conformal coatings continue to become ever more challenging, as electronics are increasingly subjected to ever more hostile operating environments.  Simultaneously, environmental legislation continues to evolve, with an emphasis on reducing solvent usage and Volatile Organic Compound (VOC) emissions. The use of solvent-less silicone conformal coatings is now mature, but often these materials cannot be used due to the risk of silicone contamination, or simply their lack of protective efficiency in hostile end environments, in particular highly humid and corrosive gas environments.

The use of single component UV curable materials has grown significantly during the last decade, with rapid cure yielding productivity benefits for many. However, the current single part UV materials often suffer cure issues when applied to boards containing tall components, which shadow the exposure to UV light and necessitate out-of-focus cure heights, reducing light intensity and degree of cure.  Consequently, a secondary cure mechanism must be introduced into UV curing, typically a moisture activated or heat activated mechanism.

A new range of innovative VOC-free, fast-curing, high performance two-part conformal coatings designed for application by selective coating are introduced. The fundamental chemistry behind Electrolube’s new ‘2K’ coating materials is not new, but the 2K, solvent-free selective coating process is a new and enabling technological breakthrough, that allows all the benefits of 2K coating materials to be realised.

The 2K materials provide a solvent-free alternative to both UV and silicone materials, requiring less capital investment than UV materials and improving on the performance of most silicones in harsh environments. Electrolube subjected the new 2K range amongst UV and silicone coatings to scrutinising tests, which included thermal shock, powered salt-spray, condensation and mixed flowing gas (MFG) testing.

Using this rigorous testing data, the 2K polyurethane materials demonstrate very impressive performance when compared to other coating types.  The fact that they can be applied thickly, without cracking during thermal shock testing, enables a greater degree of component lead coverage to be achieved, resulting in improved performance during thermal shock, powered salt-spray testing, MFG testing and condensation testing, traditionally gruelling test regimes, commonly used during automotive qualification campaigns.

Read the full article with test information here