Parts are rack or barrel plated to ASTM B standard thicknesses from ” to “, depending on the base metal and application. Pure % tin is. Designation: B – 97 (Reapproved )e1 Standard Speci?cation for Electrodeposited Coatings of Tin1 This standard is issued under the. ASTM B Standard Specification for Electrodeposited Coatings of Tin.
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The use of special test specimens, their number, the material from which they are made, their size and shape, and the conditions of their coating shall be as agreed upon by the purchaser and the seller.
It is informational only and not an official part of the standard; the full text of the standard itself must wstm referred to for its use and application. Parts coated with tin can be assembled safely in contact with iron and steel, tin-coated aluminum, yellow chromated zinc, cadmium, and solder coatings.
Evidence of diffusion is the formation of a layer of copper-tin intermetallic at the interface and diffusion of zinc to the surface if the substrate is brass. Porosity increases as the coating thickness decreases, so that minimum thicknesses must be specified for each application. The clamp is attached to a load cell and to a transducer, which transmits a signal to a converter that adjusts the signal to a useful mode analog or digital for the aatm instrument, computer, asmt strip-chart recorder.
Thicknesses of 30 to ? Suspend the test specimens above this solution on nonmetallic supports, with the surfaces of the specimens not less than 25 mm 1 in. These should be taken into account b54 designing for special applications. For some applications, this requirement may be relaxed to allow for a small number of such defects per unit areaespecially if they are outside of or on the periphery of signi? Moderate exposure conditions, usually indoors, but more severe than Class B.
The method provided, which depends on the production of sulfur dioxide from the reaction between sodium ast and sulfuric acid within the adtm chamber, ensures suitable conditions for the development of immobile corrosion products at discontinuities. For mill products, refer to Specifications A or AM. In normal indoor exposure, tin is protective on iron, steel, nickel, copper, and their alloys. An underplating of nickel or copper must be used as a diffusion barrier on brass.
Link to Active This link will always route to the current Active version of the standard. Where a contact mark is inevitable, its location shall be subject to agreement between the supplier and the purchaser. The buyer and seller may agree on the plan or plans to be used. Product that shows coating imperfections in subsequent manufacturing operations may be rejected.
Government Ast, Requirements S4. Some examples are given in Appendix X6. Thicker coatings are used for water containers, threaded steel couplings of oil drilling strings, and seacoast atmospheres.
The surface appearance types are matte tin electrodeposits, bright tin electrodeposits, and flow-brightened electrodeposits.
ASTM B – 13 Standard Specification for Electrodeposited Coatings of Tin
Three test methods are described in Appendix X3, while a simple dip test is given in Test Method B After removing the specimens from the corrosive atmosphere, allow them to dry without wiping or cleaning in any way, and then examine them using the options outlined in Guide BSections 6 and 7.
They shall not be stained or discolored. Practically all of g545 following methods take into account the chief cause of tin whiskering, which is the asstm of stresses in the tin coating 8: The test piece is held in a clamp that extends from an arm directly over the solder bath. Other coatings variations, such as surface appearance type 4. The maximum thickness for? Calculate the coated area in mm2 to an accuracy of at least 1 part in Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM International Headquarters.
The values given in parentheses are for information only.
The test must yield a numerical value, and certain statistical requirements must be met. Drying can reverse the reaction. The size of the sample and the criteria of compliance are determined by the application of statistics.
The thickness is less in interior corners aastm holes. Diffusion may lead to darkening of a thin coating and impairment of its solderability characteristics, particularly after long storage.
MIL-T-10727 vs. ASTM B545
ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. There needs to be sufficient free tin below the oxide layer in order for this to occur, because the intermetallic compounds formed from tin and the basis metal will not react in this way 7.
With such thin coatings, a diffusion barrier of nickel may be advantageous, although users should also consider the use of thicker coatings when solderability must be maintained over a period of years 6. Where electroplated tin coatings are subject to long-term storage or use at very low temperatures, it may be advisable, when speci?
Coatings shall be grouped into six service classes, which is based on the minimum thickness and severity of service required for the coating, and three surface appearance types, which asstm based on the type electroplating process employed. Class A is often used for tin coatings that are not to be soldered, but must function as low-resistance electrical contact surfaces.