Electroless tin@-lead@ solder plating bath - contains trivalent titanium based reductant and complexing agent

摘要

An electroless solder metallising bath contains Sn(II) and Pb(II) as metal ions, a complexing agent and a reductant which includes Ti(III) ions. A suitable bath has the compsn. 0.05-0.50 mol/l trisodium citrate, 0.02-0.16 mol/l EDTA disodium salt. 0.05-0.40 mole/l nitrilotriacetic acid. 0.02-0.16 mol/l tin(II) chloride + lead(II) chloride and 0.02-0.08 mol/l titanium trichloride. The bath is at 40-80 deg.C and has pH 5-11. ADVANTAGE - The Ti(III) reductant allows electroless metallisation of metal (e.g. Cu or Ni) or non-conductive substrates to any desired deposit thickness and compsn.