Influence of Etchants on Etched Surfaces of High-Strength and High-Conductivity Cu Alloy of Different Processing States

• Published in: Materials Vol. 17; no. 9; p. 1966
• Main Authors: Fang, Jinyang, Zhang, Qingke, Zhang, Xinli, Liu, Feng, Li, Chaofeng, Yang, Lijing, Xu, Cheng, Song, Zhenlun
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 01.05.2024
• Subjects: Accuracy; Acids; Alloys; Annealing; Atoms & subatomic particles; Cold; Copper base alloys; Copper chloride; Cu alloy; Electric properties; Etchants; Etching; Ferric chloride; Grain boundaries; Grain orientation; Grooves; High strength alloys; Ion concentration; Microstructure; Morphology; Raw materials; Rolling texture; roughness; Semiconductor devices; Specialty metals industry; surface morphology; Surface properties; Surface roughness; Temperature; Cu alloy; copper chloride; surface morphology; ferric chloride; etching; roughness
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma17091966

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 FeCl and two CuCl 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 FeCl and CuCl 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 FeCl and CuCl etchants. For the same kind of etchant, the ion concentration can affect the etching mechanism, rate and the etched surface morphology.