Solder for use on surfaces coated with nickel by electroless plating
A solder which can form a soldered joint of good bonding strength on a Ni layer containing a small amount of P formed from electroless Ni plating with a P-containing plating solution comprises 60–64 mass % of Sn, 0.002–0.01 mass % of P, 0.04–0.3 mass % of Cu, and a remainder of Pb. The solder is particularly suitable for forming a solder bump on a Cu electrode which has been coated with Ni by electroless plating.
1. A solder for use in soldering to a surface coated with nickel by electroless plating with a phosphorus-containing plating solution, consisting of 60–64 mass % of Sn, 0.002–0.01 mass % of P, 0.04–0.3 mass % of Cu, and a remainder of Pb.
2. A solder as claimed in claim 1 which is in the form of a solder ball, a solder paste, preformed solder, wire solder, or flux-cored wire solder.
3. A soldering method comprising soldering the solder claimed in claim 1 to a surface coated with nickel by electroless plating with a phosphorus-containing plating solution.
4. A soldered joint comprising the solder claimed in claim 1 formed on a surface coated with nickel by electroless plating with a phosphorus-containing plating solution.
5. A method of forming a solder bump comprising heating a solder ball comprising the solder claimed in claim 1 on a surface coated with nickel by electroless plating with a phosphorus-containing plating solution.
6. A solder bump comprising the solder claimed in claim 1 formed on a surface coated with nickel by electroless plating with a phosphorus-containing plating solution.
7. A substrate for a ball grid array package including a plurality of solder bumps comprising the solder claimed in claim 1 disposed on Cu electrode pads coated with nickel by electroless plating with a phosphorus-containing plating solution.
8. A solder as claimed in claim 1 containing 0.004–0.008 mass % of P.
9. A solder as claimed in claim 1 containing 0.06–0.2 mass % of Cu.