The typical CuproBraze temperature cycle calls for a slow heatup to let binder in the brazing paste burn off (A). The heat-exchanger core and fixture are allowed to equalize at around 550°C before brazing begins (B). The brazing period begins when the brazing powder reaches 600°C. Here, the filler metal wets and alloys with the base metal (C). Cooldown should be 1°C/sec or slower to 550°C to prevent thermal distortion (D).