The invention relates to a lead-free and
halogen-free
soldering paste and a preparation process thereof, and belongs to the technical field of
soldering paste production, through the combination of nano-silver-loaded carbon nanotubes, organically coated
solder alloy powder and
soldering flux, the
surface tension of the lead-free and
halogen-free soldering paste can be reduced by
carbon nanotube surface carboxyl in the nano-silver-loaded carbon nanotubes, so that the lead-free and
halogen-free soldering paste is obtained. Nano-silver and
tin form an Ag3Sn strengthening phase which synergistically promotes
wetting and spreading of the solder on a substrate, meanwhile, the carbon nanotubes loaded with the nano-silver are uniformly dispersed in the soldering paste to play a dispersion strengthening role, and the
brittleness caused by
bismuth segregation is effectively inhibited in cooperation with the grain refinement effect of
copper and
indium in the
solder alloy powder; and the organic
coating layer hydrogenated
rosin-
terpene resin and the soldering flux
alcohol ether solvent form a slight
dissolution-fusion effect, so that the
welding flux
alloy powder is prevented from being oxidized, an
organic acid active agent can be released to remove a substrate oxidation film, the metallurgical bonding quality of a
welding interface is further guaranteed, and the defects of pseudo soldering, cavities and the like are reduced.