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Low Temperature Immersion Tin

IP.com Disclosure Number: IPCOM000043578D
Original Publication Date: 1984-Sep-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Casullo, FJ: AUTHOR

Abstract

Preventing immersion tin baths from solidifying at temperatures below 140ŒF provides the conditions which allow required amounts of tin deposits at low temperatures. To produce a low temperature immersion tin bath, the following combinations of chemicals were formulated and studied (listed in order of addition to water at temperatures between 130ŒF and 150ŒF with the solutions stirred when adding chemicals): 1. Citric Acid 10-30 g/l 2. Stannous Fluoborate 40-80 ml/l (of which 13-26 g/1 is stannous tin) 3. Sulfuric Acid (36N) 10-30 ml/l 4. Thiourea 40-50 g/l 5. Compatible Surfactant 0-15 ml/l Filter the final solution and continue to filter while it is being used. Stable tin deposition rates can be achieved at bath temperatures as low as 100ŒF.

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Low Temperature Immersion Tin

Preventing immersion tin baths from solidifying at temperatures below 140OEF provides the conditions which allow required amounts of tin deposits at low temperatures. To produce a low temperature immersion tin bath, the following combinations of chemicals were formulated and studied (listed in order of addition to water at temperatures between 130OEF and 150OEF with the solutions stirred when adding chemicals): 1. Citric Acid 10-30 g/l 2. Stannous Fluoborate 40-80 ml/l (of which 13-26 g/1

is stannous tin)

3. Sulfuric Acid (36N) 10-30 ml/l

4. Thiourea 40-50 g/l

5. Compatible Surfactant 0-15 ml/l Filter the final solution and continue to filter while it is being used. Stable tin deposition rates can be achieved at bath temperatures as low as 100OEF.

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