B545-13 Standard Specification for Electrodeposited Coatings of Tin

Designation: B545-13 Standard Specification for Electrodeposited Coatings of Tin1 1. Scope 1.l This specification covers the requirements for electrode-posited (electroplated) coatings of tin applied to metallicarticles. Tin coatings are used to provide a ow contact-resistance surface.to protect against corrosion (see 1.2).tofacilitate soldering, to provide anti-galling properties,and to bea stopoff coating in thc nitriding of high-strength stecls. 1.2 Some corrosion can be expected from tin coatingsexposed outdoors. In normal indoor exposurc, tin is protectiveon iron, steel, nickel, copper. and their alloys. Corrosion can beexpected at discontinuities in the coating (such as pores) due togalvanic couples formed bctween the tin and the underlyingmetal through the discontinuities.especially in humid atmo-spheres.Porosity increases as the coating thickness decreases.so that minimum thicknesses must be specified for cachapplication. Parts coated with tin can be assembled safely incontacr with iron and steel， tin-coated aluminum. yellowchromated zinc. cadmium, and solder coatings. (See Xs.1 foroxidation and corrosion propertics.) 1.3 This specification applies to electroplated coatings ofnot less than 99 % tin (except where deliberately alloyed forspecial purposes.as stated in X6.3) obtained from any of theavailable tin electroplating processes (see 4.3). 1.4 This specification does not apply to hot-dipped tin orother non-electrodeposited coating; it also does not apply tomill products. For mill products.refer to Specifications A623or A623M. 1.5 The valucs stated in Sl units are to be regarded as thestandard. The values given in parentheses are for informationonly. l.6 This standard does nor purporr to address all of thesafety conceras，if any,associated wih irs use. I is rheresposibility of the user of this standard to establish appro-priate safery and heairha practices cand deteranine rhe applica-biliy of veguelatory liitotions prior to uase.