TWI

Defects and their mitigation associated with the fabrication of fluid-cooled aluminium alloy heatsinks for electronic applications are discussed. The heatsink consisted of an aluminium alloy 6063 substrate (310 x 300 mm) with a series of rectangular slots machined in one face. The tops of the slots were closed using strips of aluminium alloy of 4-12 mm thickness, recessed into face, such that the sealing strips were flush with the surface of the heatsink. The edges of the strips formed butt joints with the side faces of the slots, and the joints were sealed by friction stir welding, so forming a series of sub-surface channels through which the cooling fluid could pass. The influences of the substrate surface cleanliness, joint preparation, the number of runs, sealing strip thickness, and welding sequence on heatsink distortion, crack formation, and cavity formation are discussed, with measures to mitigate the occurrences.

11th International Symposium, 17-19 May 2016, Poster Session, Paper 04