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AUGUST 2019 I SMT007 MAGAZINE 17 condensation, damage resistance from insects, liquid water ingress, and corrosive gases. For example, 2K materials are commonly used in high-performance industrial applica- tions, such as adhesives, paints, and even pot- ting materials. The systems consist of a resin portion and a cross-linker portion that are rea- sonably stable when kept separate. However, once mixed in the correct ratio, an unstoppa- ble chemical reaction begins, which continues until a solid polymer is formed. By adjusting the nature of the resins and the hardeners, a wide variety of polymers can be produced from soft rubber-like materials to high-strength glass-like materials. Many of these materials are diluted with solvents, which increases the usable life of the system and enables the use of existing application methodologies. However, with the restrictions on solvent usage, it was decided to focus on generating a solvent-free solution. Do I Need to Make Any Changes to My Existing Selective Coating Equipment? Electrolube has collaborated closely with popular selective coating equipment suppli- ers—such as ANDA, PVA, and ASYMTEK— to ensure that the thicker 2K formulations are fully optimised for application using commer- cially available dispensers. Together, they have developed and tested 2K applicators that pro- vide customers with a retrofit upgrade to their existing and new equipment. The minor mod- ification consists of metering pumps and con- trollers to ensure the correct volumetric mix ratio of the materials and a new spray appli- cator that mixes the materials immediately before spraying. For precision work, it is possible to apply via a needle dispenser also. For instance, PVA's new two-component spray valve—VPX-2KS— has proved to be a highly successful modifi- cation for users of selective coating systems (figure 10), adapting easily into their existing equipment to ensure excellent control of mate- rial flow, improved edge definition, and easier regulation of dispensing starts and stops. Conclusion In comparison to single coatings, two-part (2K) conformal coatings can achieve impres- sive full coverage of components at higher film thicknesses, which results in unparalleled Figure 9: Condensation resistance of conformal coatings on a BGA component.