Metal Finishing Guide Book

2011-2012 Surface Finishing Guidebook

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Table VII. Troubleshooting 60 Tin/40 Lead Solder Baths Problem Cause Poor throw Low tin and lead Low acid Low additive High anode to cathode ratio Organic contamination Gassing Treeing Lack of adhesion Burning Graininess Roughness Too high current density Organic contamination Low additive Low acid Poor cleaning Low tin and lead Low acid Too high current density Organic contamination Organic contamination Solids in bath Stannic tin Chloride/sulfate contamination Incorrect alloy Metallic contamination Low acid Wrong current density Improper agitation Incorrect anodes Unsatisfactory reflow Incorrect tin to lead ratio Incorrect thickness Dewetting caused by: Poor cleaning Organic contamination High reflow temperature Incorrect alloy Remedy Increase tin and lead. Increase acid. Add additive. Remove several anodes. Carbon treat. Lower current density. Carbon treat. Add additive. Increase acid. Correct cleaning cycle. Increase tin and lead. Increase acid. Lower current density. Carbon treat. Carbon treat. Filter. Filter and exclude air from bath. Filter bath and check cleaning cycle. Dummy the bath. Increase acid. Use correct current density. Use proper agitation. Use anodes with correct composition. Analyze bath and correct ratio. Use correct plating time. Correct cleaning cycle. Use proper temperature. Carbon treat. See Problem: "Incorrect alloy" above. Tin Table VIII. Stannous Sulfate Bath Composition and Operating Conditions Range (g/L) 30-50 Sulfuric acid, 100% Additive Anodes Current density, A/ft2 Anode to cathode ratio Temperature, OF (OC) Agitation Filtration Pumps and tanks Heaters and coolers 252 100-140 As recommended by manufacturer Pure tin 1-25 1:1 70-85 (21-29) Cathode and solution 1 ┬Ám Dynel or polypropylene cartridges Polyethylene, polypropylene, rubber Karbate Optimum (g/L) 40 120

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