| 摘要 |
PROBLEM TO BE SOLVED: To reduce the deterioration of a plating soln. due to the generation of sludge by specifying the bubble volume ratio in the soln. and controlling the soln. through an oxygen-enriched tank, tin dissolving tank and electroplating tank. SOLUTION: Electro tin plating is conducted by using an insoluble anode. An oxygen-contg. gas having 0.01-10,000μm average bubble diameter is blown into an oxygen-enriched tank formed separately from an electroplating tank, and the bubble volume ratio is adjusted to <=0.1% in the oxygen-enriched tank. The obtained plating soln. contg. dissolved oxygen is supplied to a tin dissolving tank holding metallic tin to dissolve tin, and the plating soln. is circulated through the oxygen-enriched tank, tin dissolving tank and electroplating tank. The vapor-phase pressure in the upper space in the oxygen-enriched tank is controlled to 0.2-10 MPa (absolute pressure). Consequently, the resources and manpower are saved, and the production efficiency and product quality are remarkably improved.
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