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Tin/Lead Electroplating Module
-Titration Analysis Techniques/Tin Analysis
Tin (as stannous tin) Analysis
If you have not done so, please read the DO's and DON'Ts section now.
- Titration flask (125 ml)
- 10 ml Automatic pipette
- Digital titrator
- 0.5 gram measuring spoon
- Iodide-iodate standard titration cartridge
- Hydrochloric acid, conc., ACS
- Sodium bicarbonate, ACS
- Starch indicator solution
- Measure 30 ml of deionized water into the 125 ml titration flask. (Quantity is not critical)
- Add 1.0 ml of the plating bath using the automatic pipettor.
- Add 10 ml of CONCENTRATED Hydrochloric acid or 20 ml of 1:1 hydrochloric acid. Swirl to mix.
GLOVES, APRON AND FACE SHIELD SHOULD BE WORN
WHEN HANDLING THE FLASK AND THE CONCENTRATED ACIDS.
- Heat the flask until it is hot to the touch. This can be accomplished by putting the flask in the curing oven for 5 minutes with the oven set at 100°C.
- Add one dropper-full of Starch indicator solution and slowly add one 0.50 g measuring scoop of Sodium bicarbonate. Swirl to mix.
- Titrate immediately with the Iodate-iodide standard to the appearance of a blue end point. Swirl the flask continuously to assure proper mixing during titration. Record the number of digits (denoted NUMTIN) required to reach the end point.
- To determine the concentration of Stannous tin ion (SnII) present in the sample, calculate using:
Sn(II) = NUMTIN x 0.0742 g/l
Sn(II) = NUMTIN x 0.0099 oz/gal
- Assuming that you are using LeaRonal SolderOn Tin Concentrate (STC) with 120 g/l of tin metal, the amount needed to replenish the 38 liter (10 gallon) bath to the optimum point of 16 g/l, is calculated by:
STC needed = (216-NUMTIN) x 0.0062 liters
STC needed = (216-NUMTIN) x 0.0016 gal
The acceptable range of digital titrator readings is
|Acceptable Range Sn(II):
||13.0 to 20.0 g/l
||175 to 270
HANDLE WITH CARE
Always wear protective clothing, acid resistant gloves, and a full coverage face shield
when handling this or any other corrosive material.
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