A plate heat exchanger includes a plurality of main plates stacked to define a first cavity to direct a first fluid therethrough and a second cavity to direct a second fluid therethrough, the second fluid different from and kept separated from the first fluid. Each main plate has one or more peaks and one or more valleys formed therein. A ratio of wavelength between adjacent peaks or between adjacent valleys of the main plate to an amplitude between a peak and an adjacent valley of the main plate is equal to or greater than 7.0.