But when the role of cathode polarization over a certain range, the precipitation will lead to a lot of hydrogen, so that coating has become porous and rough, loose, burned, or even powder form, instead of declining quality. Additive free fluoride content and boric acid content is too high or too low when the main concentration, the coating will have serious shortcomings. 4.2.7 the impact of temperature with increasing temperature, bath in the composition of the dissolution of the increase in the concentration of the desirable limit. DK which is conducive to the increase, thereby speed up the deposition rate. However, the temperature too high too quickly dissolved anode, anode slime increased so that the solution turbidity, coating nodulation. At the same time free fluoride boric acid, volatile organic stability agent to speed up, smell increasing deterioration of the environment. The temperature is too low free-boric acid precipitation, bath muddy, rough plating; Meanwhile DK or not to effect deposition slow, low production efficiency. 5 testing process used L9 (34) orthogonal test identified in the bath [Pb2 +], free [HBF4], free [H3BO3] DK and technical parameters of the best value. 5.1 anode composition test conditions: PbSn10; Temperature: 20 ~ 25 ℃; power: three-phase full-wave silicon rectifying; specimen geometry: 100 × 50 × 4; specimens lining (was plated base) the composition: CuPb22Sn2 ; Specimens lining the surface roughness: Ra0.4.
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