Copper brazed heat exchangers are constructed with a series of thin, corrugated stainless steel plates that are closely spaced to maximize heat transfer surface area. These plates are sandwiched between thicker frame and pressure plates, which provide structural support. The assembly is vacuum brazed using a copper or copper alloy filler material, which melts and flows into the grooves between the plates, creating a hermetically sealed joint that ensures no leakage and excellent heat conductivity.