With the continuous integration of semiconductor devices, the requirements of the size accuracy and surface quality of etched lead frames are stricter. The etchant is a key factor in the etching process and etched surface quality, while the effects of the difference in etchants on the etched surface morphology of Cu alloy have not been directly studied. In this study, aqua regia, acidic FeCl₃ and two CuCl₂ solutions were used as etchants, and different CuCrSn specimens were etched and characterized. The results show that the etching rate in aqua regia is high, and the grain orientation, grain boundary (GB) and dislocations have significant influences on the local etching rate. The preferential etching of some atomic planes forms steps between the grains with different orientations, and preferential etching around the GB and dislocation group forms grooves, resulting in high surface roughness. For the surfaces etched by the FeCl₃ and CuCl₂ etchants, the steps and grooves are blurred; thus, they are less rough. The CuCrSn alloy surface etched by the aqua regia is clean, with little Cr-rich particles, while high-density Cr-rich particles remain on the surfaces etched by the FeCl₃ and CuCl₂ etchants. For the same kind of etchant, the ion concentration can affect the etching mechanism, rate and the etched surface morphology.

To obtain ultrahigh strength Cu alloy strip for board-to-board connectors, a CuNiSiMgMn multi-element high-solute alloy was designed, and high-temperature short-time solid solution was utilized to optimize the properties of this alloy. The evolution in microstructure and properties of the cold-rolled CuNiSiMgMn alloy strip during high-temperature short-time solid solution, aging, and further cold-rolling are investigated. The results reveal that there are high-density Ni_xSi precipitates and deformation defects in the original cold-rolled CuNiSiMgMn alloy strip. During a solid solution at 1000 °C, recrystallization primarily occurs between 15 and 30 s, while precipitate decomposition starts at a solid solution time of ~30 s and is almost complete 10 s later. With further increase in the solid solution time, the grain size of the alloy grows rapidly, but the residual precipitate particles exhibit little change. Upon aging at 500 °C for 2 h and a further 80% cold-rolling, nano-sized precipitates are formed, yielding high-strength alloy strips. The 80% cold-rolling increases the microhardness by 12% and decreases the electrical conductivity by 3% IACS. The strip solid solution-treated for 35 s exhibits the maximum strength, with a tensile strength of >950 MPa and a conductivity of >30% IACS. Further extension of the solid solution time decreases both the tensile strength and elongation. This work clarifies the critical time of recovery, recrystallization, and precipitate decomposition of the CuNiSiMgMn alloy during high-temperature solid solution and provides guidance for industrial production.

With continuous increase in integration of the semiconductor devices, the requirements on size accuracy and surface quality of the etched lead frame are higher. The etchant is a key factor on etching process and etched surface quality, while effects of the difference in etchants on microscopic etched surface morphology of the Cu alloy have not been directly studied. In this study, the aqua regia, acidic FeCl3 and CuCl2 solutions were used as etchants, and the CuCrSn alloy specimens with different microstructure were etched and characterized. The results show that the etching rate in aqua regia is high, and the grain orientation, grain boundary (GB) and dislocation have significant influence on the local etching rate. The preferential etching of some atomic planes forms steps between grains with different orientations, and the preferential etching around the GB and dislocation group forms grooves, resulting in high surface roughness. For etching of the FeCl3 and CuCl2 etchants, the steps and grooves become blurred, and almost invisible on the surface etched by the CuCl2 etchant, thus the surface roughness is much lower. The CuCrSn alloy surface etched by the aqua regia is clean, with little Cr-rich particles, while high density Cr-rich particles are remained on the surfaces etched with the FeCl3 and CuCl2 etchants. For the same kind of etchant, the ion concentration can affect the etching mechanism and etching surface morphology.