Extrusion limits of magnesium alloys

Magnesium alloys are generally found to be slower to extrude than aluminum alloys; however, limited quantitative comparisons of the actual operating windows have been published. In this work, the extrusion limits are determined for a series of commercial magnesium alloys (M1, ZM21, AZ31, AZ61, and ZK60). These are compared with the limits established for aluminum alloy AA6063. The maximum extrusion speed of alloy M1 is shown to be similar to AA6063. Alloys ZM21, AZ31, ZK60, and AZ61 exhibit maximum extrusion speeds 44, 18, 4, and 3 pct, respectively, of the maximum measured for AA6063. For AZ31, the maximum extrusion speed is increased by 22 pct after homogenization and by 64 pct for repeat extrusions. The variation in the extrusion limits with changing alloy content is rationalized in terms of differences in the hot working flow stress and solidus temperature.<br /

Reliability of electronics assembled using SAC + Zn solder pastes

A method of preparing SAC solder with addition of 1.0-1.5wt.% Zn to Sn-3.8Ag-0.7Cu solder alloy such that a standard solder paste reflow process results in good soldering is described. Solder-substrate couples were aged at 150°C for 1000h, and results on temperature cycling (−20 to 175°C) and shear testing of solder joints is also described. The added Zn segregated to the interfacial IMCs so that Cu6Sn5 became (Cu,Zn)6Sn5 and (Cu,Ni)6Sn5 became (Cu,Ni,Zn)6Sn5. The reliability of assemblies utilizing Electroless Nickel Immersion Gold (ENIG) using the Zn enhanced solder is compared to that of standard SAC solder alloy for potentially reliable operation at temperature up to 185°C.</jats:p