Contact reaction brazing process of aluminum alloy to copper with LHG-S2 brazing paste

A new brazing paste and its application in brazing of aluminum alloy to copper of CPU radiator with LHG-S2 brazing paste were introduced. According to the configuration of the aluminum alloy-copper radiator, brazing process using brazing paste was analyzed. The results show that the brazing can be operated successfully in inert-gas furnace ace. During the brazing, obvious reactors is produced between aluminum alloy radiator and copper, and the reaction liquid diffuses preferentially along grain boundary to the base. As reaction liquid occurs at the contact point, the reaction relies on the diffusion and the diffluence of Si atom, Al atom and Cu atom from the solid-liquid interface to the reaction liquid. Al-Si-Cu and pure Al are formed at the reaction interface. Microstructure analysis of the joint shows that, aluminum alloy radiator to copper sheet is fully joined by LHG-S2 brazing paste, and the high thermal transition and the nice shape of the radiator are obtained using this method.