HB 20056.3-2011 "Sn-bismuth alloy platings and Eletroplating tin-bismuth alloy solution analysis method, Part 3: Determination of stannous sulfate content by oxidation reduction method" specifies the principle, reagents, analysis steps and result calculation method for the determination of stannous sulfate content in Eletroplating tin-bismuth alloy solution by oxidation reduction Titrimetric method. This part is suitable for the determination of stannous sulfate content in Eletroplating tin-bismuth alloy solution. Measurement range is 30g/L~ 65g/L. During the analysis process, divalent tin oxidation was changed to tetravalent tin using iodine standard solution in sodium carbonic acid medium, and soluble starch solution was used as an indicator. Calculate the content of stannous sulfate in the solution based on the volume of the standard solution of iodine consumed. This standard refers to "Reagents for Analysis of Metal Plating and Chemical Covering Solutions" (HB/Z5083-2001) and requires the use of reagents that meet its requirements for analysis.