SOLDER FREE FROM LEAD FOR ADDITIONAL SUPPLY AND METHOD OF REGULATING Cu CONCENTRATION AND Ni CONCENTRATION IN SOLDER BATH
AssigneeNihon Superior Sha Co., Ltd.
InventorTetsuro Nishimura
Life of this patent
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Abstract
Lead-free solder is replenished to a solder bath to receive a work having copper, the work to be processed subsequent to a soldering process using an air knife or a die. The replenished lead-free solder includes Sn as a major composition and at least 0.01 to 0.5 mass percent Ni. By replenishing the lead-free solder having the above composition, the density of the solder bath, being sharply changed for using one of a HASL device and a die, is quickly restored back to within an appropriate range.
Claims12
A Lead-free solder to be replenished to a solder dipping bath that receives a work including one of a printed circuit board having copper film coated thereon, a copper lead wire, and a copper tape, the work to be processed subsequent to a soldering process using one of an air knife and a die, the lead-free solder comprising 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.
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.
Dependencies are inferred from the claim text.