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16 SMT007 MAGAZINE I AUGUST 2019 Many boards have been cross-sectioned after selective coating to ensure coverage and thick- ness requirements are achieved (Figures 5–7). Following intensive powered condensation testing on automotive and aerospace assem- blies, Electrolube's 2K300 demonstrated out- standing protection compared to the next best coating. The 2K materials have also under- gone the BMW dewing test and the NPL's new condensation test on SIR test boards with par- ticularly positive results and with little differ- ence between damp and dry conditions in the cycling test (Figures 8 and 9). Higher insula- tion resistance values are desirable, as is recov- ery to similar levels between wet and dry con- ditions. Low insulation resistance values that remain low are indicative of corrosion or elec- trochemical migration (ECM). Which Applications Are Most Suitable for 2K? 2K materials are ideally suited for harsh and demanding applications. The coatings are par- ticularly suitable for automotive applications where the combination of high-temperature resistance, long-term flexibility to survive ther- mal shock cycling, and an unsurpassed abil- ity to withstand corrosive gases, aggressive media—such as transmission and brake flu- ids—and powered salt spray. Condensation/ dewing tests take their protective capabili- ties to the next level. The materials also pro- vide resistance to total immersion in saltwater whilst under load for at least 30 hours. However, 2K materials have also been ben- eficial to military and aerospace customers, as well as industrial controls and white goods manufacturers, with 2K improving resistance to Figures 5–7: Examples of cross-sections of PCB components/ component legs showing coating coverage. Figure 8: SIR test board used for BMW Dewing and NPL condensation tests.