The invention provides a plating solution capable of forming a palladium plating film which can further improve solder characteristics in surface treatment of a composition made of a nickel plating film, a palladium plating film and a gold plating film on a surface of a conductor formed from a metal such as copper. In a palladium plating solution of the invention containing a soluble palladium salt and an electrically conductive salt having a liquid composition containing germanium, the amount of the soluble palladium salt is 0.1 g/l to 50 g/l in terms of a reduced value of palladium metal, the amount of the electrically conductive salt is 10 g/l to 400 g/l and the amount of the germanium is 0.1 mg/l to 1000 mg/l.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a flowchart of fabrication of a sample for evaluating solder wettability.
Claims
1. A palladium plating solution containing a soluble palladium salt and an electrically conductive salt, wherein the palladium plating solution contains germanium.
2. The palladium plating solution as defined in claim 1, wherein the soluble palladium salt contains an amino group-based palladium complex or an ammonia-based palladium complex.
3. The palladium plating solution as defined in claim 1, wherein the soluble palladium salt comprises one or more of dichloroethylenediamine palladium (II), palladium chloride, dichlorodiammine palladium (II), dinitrodiammine palladium (II), tetraammine palladium (II) nitrate, tetraammine palladium (II) sulfate, oxalatodiammine palladium (II), tetraammine palladium (II) oxalate and tetraammine palladium (II) chloride, and wherein the electrically conductive salt is at least one kind selected from the group consisting of an ammonium salt, a sodium salt and a potassium salt of hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid and citric acid.
4. The palladium plating solution as defined in claim 1, wherein the amount of the soluble palladium salt is 0.1 g/l to 50 g/l in terms of a reduced value of palladium metal, the amount of the electrically conductive salt is 10 g/l to 400 g/l and the amount of the germanium is 0.1 mg/l to 1000 mg/l.
5. A method of palladium plating comprising plating palladium with a plating solution comprising a soluble palladium salt, an electrically conductive salt, and germanium, at a plating solution temperature of 25 to 70° C., a pH of 6.0 to 10.0 and a current density of 0.10 A/dm2 to 5.00 A/dm2.
6. The palladium plating solution as defined in claim 2, wherein the amount of the soluble palladium salt is 0.1 g/l to 50 g/l in terms of a reduced value of palladium metal, the amount of the electrically conductive salt is 10 g/l to 400 g/l and the amount of the germanium is 0.1 mg/l to 1000 mg/l.
7. The palladium plating solution as defined in claim 3, wherein the amount of the soluble palladium salt is 0.1 g/l to 50 g/l in terms of a reduced value of palladium metal, the amount of the electrically conductive salt is 10 g/l to 400 g/l and the amount of the germanium is 0.1 mg/l to 1000 mg/l.
8. The method of claim 5 where in the soluble palladium salt contains an amino group-based palladium complex or an ammonia-based palladium complex.
9. The method of claim 5 where in the soluble palladium salt comprises one or more of dichloroethylenediamine palladium (II), palladium chloride, dichlorodiammine palladium (II), dinitrodiammine palladium (II), tetraammine palladium (II) nitrate, tetraammine palladium (II) sulfate, oxalatodiammine palladium (II), tetraammine palladium (II) oxalate and tetraammine palladium (II) chloride, and wherein the electrically conductive salt is at least one kind selected from the group consisting of an ammonium salt, a sodium salt and a potassium salt of hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid and citric acid.
10. The method of claim 5 wherein the amount of the soluble palladium salt is 0.1 g/l to 50 g/l in terms of a reduced value of palladium metal, the amount of the electrically conductive salt is 10 g/l to 400 g/l and the amount of the germanium is 0.1 mg/l to 1000 mg/l.
11. The method of claim 8, wherein the amount of the soluble palladium salt is 0.1 g/l to 50 g/l in terms of a reduced value of palladium metal, the amount of the electrically conductive salt is 10 g/l to 400 g/l and the amount of the germanium is 0.1 mg/l to 1000 mg/l.
12. The method of claim 9, wherein the amount of the soluble palladium salt is 0.1 g/l to 50 g/l in terms of a reduced value of palladium metal, the amount of the electrically conductive salt is 10 g/l to 400 g/l and the amount of the germanium is 0.1 mg/l to 1000 mg/l.
Patent Application
20070205109
