| 摘要 |
PROBLEM TO BE SOLVED: To provide a printed circuit board and surface treatment technique therefor for maintaining and securing excellent solderability even after long-period storage by preventing temporal oxidation discoloration and corrosion of a copper land portion of the printed circuit board and for securing soldering connection reliability when an electronic element is mounted on a copper land portion of the printed circuit board on one surface and soldered for second and succeeding times by preventing deterioration in solderability by preventing oxidation discoloration of an unmounted copper land portion on the opposite surface when an electronic element is mounted on a copper land portion of the printed circuit board and soldered, surface by surface, like a both-surface printed circuit board and a multilayer printed circuit board. SOLUTION: The printed circuit board having excellent solderability even after long-period storage is obtained by forming a discoloration-resistive, rust-proofing protective coating film which hardly discolors even after high-temperature exposure at the copper land portion of the printed circuit board through a first process of subjecting the printed circuit board to impregnation treatment in a solution of 80 to 300°C in liquid temperature, consisting of 5 to 80% by weight of organic fatty acid with C13-20 and ester synthetic oil for the balance, and a second process of subjecting the printed circuit board to impregnation treatment in a solution consisting of 1 to 20% by weight of organic fatty acid thiol with C13-20, 0.1 to 5% by weight of an emulsifier, and water for the balance and uniformly emulsified to an emulsified particle size of≤3μ. COPYRIGHT: (C)2009,JPO&INPIT
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