A heat exchanger assembly including at least one aluminum based tube having an internal surface and an external surface, an aluminum based lithium-magnesium composition cladding applied to either one of the internal surface and external surface of the tube, and at least one aluminum based component disposed adjacent the cladding, a modified aluminum brazing flux applied to a joint between the surface and one component. The modified aluminum brazing flux comprises cesium fluoride, lithium fluoride, or both. Preferably, the cladding further comprises cesium. To manufacture the heat exchanger assembly, the tube and component are joined together with flux applied in the area of the joint using a controlled atmosphere brazing (CAB) process.