Patent ID: 7861909
Filing Date: 2011-01-04
Classification: B23K,C22C,H05K

Abstract:
1. A control method for Cu density and Ni density in a solder dipping bath comprising a step of immersing a work including one of a printed circuit board having copper film coated thereon, a copper lead wire, and a copper tape into the solder dipping bath for soldering, and circulating solder, removed from the work by one of an air knife or a die, back into the solder dipping bath, wherein lead-free solder is replenished to the solder dipping bath before the Cu density in the solder dipping bath is increased by a maximum of 0.5 mass percent from a predetermined value and the Ni density in the solder dipping bath is decreased by a maximum of 0.03 mass percent from a predetermined value, the lead-free solder to be replenished including Sn as a major composition and at least Ni having a density falling within a range from equal to or higher than 0.01 mass percent to equal to or lower than 0.5 mass percent.