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ASTM Designation: B 545

Electrodeposited Coatings of Tin

ClassMinimum ThicknessTypical Applications

2.5 µm (100 µin) Mild service conditions, particularly where the significant surface is shielded from the atmosphere (as in electronic connector housings.)
5 µm (200 µin) Mild service conditions with less sever requirements than Class C.
8 µm (320 µin)10 µm (400 µin) for steel substrates
Moderate exposure conditions, usually indoors, but more severe than Class B.
15 µm (600 µin)20 µm (800 µin) for steel substrates Severe service, including exposure to dampness and mild corrosion from moderate industrial environments.
30 µm (0.0012 in) Very severe service conditions, including elevated temperatures, where underlying metal diffusion and intermetallic formation processes are accelerated.
1.5 µm (60 µin.) Similar to Class A, but for shorter-term contact applications and short shelf-life requirements, subject to purchaser approval.

Surface Appearance Type (Electroplating Process)
Matte Tin Electrodeposits – Coating with a matte appearance are obtained from tin plating baths (stannate, sulfate, methylsulfonate, and fluoborate) used without the addition of brightening agents.
Bright Tin Electrodeposits – Bright coatings are obtained when proprietary brightening agents are used in specific bright tin plating baths.
Flow-Brightened Electrodeposits – Flow –brightened coatings are obtained by heating the matte coating above the melting point of tin for a few seconds, followed by quenching.

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