Patent ID: 7632343

Claim:
An electroless palladium plating solution comprising: a first complexing agent, a second complexing agent, phosphoric acid or a phosphate, sulfuric acid or a sulfate, and formic acid or a formate; said first complexing agent being an organopalladium complex having ethylenediamine as a ligand, wherein said first complexing agent is selected from the group consisting of dichlorodiethylenediamine palladium, dinitritediethylenediamine palladium and diacetatediethylenediamine palladium which are respectively synthesized by preliminary reacting ethylenediamine as a ligand with an inorganic palladium salt in a molar ratio of 2:1; said second complexing agent being a chelating agent having carboxyl groups or a salt thereof and/or a water-soluble aliphatic organic acid or a salt thereof, said chelating agent having carboxyl groups or a salt thereof being ethylenediaminetetraacetic acid or a sodium salt, a potassium salt or an ammonium salt thereof, said water-soluble aliphatic organic acid or a salt thereof being at least one member selected from the group consisting of citric acid, diammonium citrate, sodium citrate, potassium citrate, malic acid, ammonium malate, sodium malate, potassium malate, maleic acid, and oxalic acid.