| 摘要 |
PROBLEM TO BE SOLVED: To dissolve only solder, lead, tin and/or their alloys on a substrate without dissolving copper, copper alloy, etc., used as a substrate material by using as the dissolving solution, a hydrochloric acid solution contg. at least one metal selected from nickel, palladium and platinum as an active metal in an amount adequate to use the metal as a catalyst for the dissolution. SOLUTION: Since hydrochloric acid does not dissolve copper used as a substrate material at ordinary temp., the acid is appropriately used as an essential component of this dissolving solution for dissolving solder on a substrate, preferably in an amount sufficient to provide a 10 to 12mol/l concn. in the solution. When the hydrochloric acid concn. is <10mol/l, a long period of time is required to dissolve solder and on the other hand, when the hydrochloric acid concn. is >12mol/l, preparation of the solution becomes difficult. When the concn. of an active metal(s) selected from nickel, palladium and platinum is equivalent to an adequate catalyst amount, solder can be dissolved with the dissolving solution. In order to dissolve solder at a practical dissolution rate, a >2mg/l active metal concn. is preferred. At this time, the higher the active metal concn. is, the higher the dissolution rate becomes, however, when the concn. is >200mg/l, no incremental effect is recognized and only the cost is increased. |
