Effect of atmospheric plasma treatment on the solderability of a copper sheet with Sn-Ag-Cu alloy

An atmospheric microwave plasma pen was utilized to enhance the solderability of a copper sheet with Sn-Ag-Cu alloy (lead-free) solder. The work of adhesion of test liquids (de-ionized water, glycerol, and ethylene glycol) was increased at atreatment time of just 30 s. The contact angle of the Sn-Ag-Cu solder on the copper sheet was reduced from 53.86o to 38.46o with a treatment time of 60 s. The enhanced solderability of the copper sheet to the lead-free solder is attributed to the increased surface roughness from 313.60 to 382 nm as confirmed by atomic force microscopy.