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42 SMT Magazine • July 2016 There are a number of standards that are based around the above approaches and some of these are given here: • IEC 60068-2-30, Environmental testing - Part 2-30: Tests - Test Db: Damp heat, cyclic (12 h + 12 h cycle) • IEC 60068-2-38, Environmental testing - Part 2-38: Tests - Test Z/AD: Composite temperature/humidity cyclic test • ISO 6270-2, Paints and varnishes—Deter- mination of resistance to humidity—Part 2: Procedure for exposing test specimens in condensation-water atmospheres • ISO 16750-4, Road vehicles—Environ- mental conditions and testing for electri- cal and electronic equipment—Part 4: Climatic load. • ASTM D1735, Standard Practice for Testing Water Resistance of Coatings Using Water Fog Apparatus • ASTM D2247, Standard Practice for Testing Water Resistance of Coatings in 100 % Relative Humidity • ASTM D4585 – Standard Practice for Testing Water Resistance of Coatings Using Controlled Condensation • JIS 5600-7-2—moisture resistance (continuous condensation method) utilizing aerosol water injection • JASO D 001-94 (Japanese Automobile Standard): General rules of environmental testing methods for automotive electronic equipment While these methods can demonstrate con- trolled condensation the control and ease by which they generate condensation remains challenging. Almost all of these approaches generate condensation in humidity chambers, and this leads to a challenge, since the chamber systems are developed to minimize condensa- tion. In these cases, chambers are run very close to 100%RH, inducing condensation. However, the uniformity of this condensation within the chamber is unknown. Hence, reproducibility of the given approaches will be variable between different chambers from different manufactur- ers, and furthermore with time developments in chambers will make them less prone to suf- fering from condensation events. The approach developed overcomes many of these difficulties. None of these approaches control the sample temperature condition, and hence the uniformity of the condensed water layer is un- known and the stability of the condensed wa- ter film with time may not be constant, as the chamber control system attempt to compensate for the variance in the nominal conditions set for the chamber. The approach adopted for achieving con- densation in this study is one that can be real- ized in any humidity chamber and shows good correlation with the calculated dew point. Experimental Setup In this approach the temperature of the circuit board under test is lowered, and hence within a high humidity environment conden- sation will occur. To achieve this condition, the test boards are mounted on a platen whose temperature can be independently controlled. Hence by lowering the platen temperature be- low the chamber ambient, condensation will occur on the platen, and by the thermal cou- pling of the test board to the platen, condensa- tion will occur on that as well. There is an as- sumption that the circuit board under test has a flat unimpeded under side so that it can make good contact with the platen. In Figure 1, we show four PCBs mounted on the platen. The mounting technique is very simple: the boards are held in position on the platen surface which is at 45° by magnets. The PCBs CONDENSATION TESTING—A NEW APPROACH Figure 1: Test boards on platen.