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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B — 97 Reapproved e1 Standard Speci?
A number in parentheses indicates the year of last reapproval. A superscript epsilon e indicates an editorial change since the last revision or reapproval. This standard has been approved for use by agencies of the Department of Defense. Tin coatings are used to provide a low contactresistance surface, to protect against corrosion see 1. In normal indoor exposure, tin is protective on iron, steel, nickel, copper, and their alloys. Corrosion can be expected at discontinuities in the coating such as pores due to galvanic couples formed between the tin and the underlying metal through the discontinuities, especially in humid atmospheres.
Porosity increases as the coating thickness decreases, so that minimum thicknesses must be speci? Parts coated with tin can be assembled safely in contact with iron and steel, tin-coated aluminum, yellow chromated zinc, cadmium, and solder coatings. For mill products, refer to Speci? The values given in parentheses are for information only.
It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Current edition approved April 1, Originally approved in Last previous edition approved in as B — 97e1. The thickness of such an undercoating is usually greater than 0. This is in contrast to strikes or? Other coatings variations, such as surface appearance type 4.
Class A Minimum Thickness 2. Typical Applications Mild service conditions, particularly where the signi? To provide corrosion and tarnish resistance where greater thicknesses may be detrimental to the mechanical operation of the product for example, small electrical spring contacts and relays.
ASTM B – 13 Standard Specification for Electrodeposited Coatings of Tin
Class A is often used for tin coatings that are not to be soldered, but must function as low-resistance electrical contact surfaces. Mild service conditions with less severe requirements than Class C below.
Applications are as follows: Also found on baking pans after re? Moderate exposure conditions, usually indoors, but more severe than Class B. Asstm are electrical hardware such as cases for relays and coils, transformer cans, screened cages, chassis, frames, and?
Severe service, including exposure to dampness and mild corrosion from moderate industrial environments. Very severe service conditions, including elevated temperatures, where underlying metal diffusion and intermetallic formation processes are accelerated. Thicknesses of 30 to ? Thicker coatings are used for water containers, threaded steel couplings of oil drilling strings, and seacoast atmospheres. Coatings subject to mild etchants are included. Similar to Class A, but for shorter-term contact applications and short shelf-life requirements, subject to purchaser approval.
However, all matte baths except for stannate baths do require the addition of grainre? The maximum thickness for?
The shape of the part is also a factor;? Some examples are given in Appendix X6. NOTE 4—Thickness of electrodeposited coatings varies from point to point on the surfaces of a product see Practice B The thickness is axtm in interior corners and holes.
Such surfaces are normally exempt from the thickness requirement. If the full thickness is required on these surfaces, the electroplater will have to use special techniques that probably will increase the cost of the process.
NOTE 2—Careful preparation of metal surfaces is necessary in order to assure good adhesion and quality. The appearance shall be uniform throughout, insofar as the basis metal will permit. They shall be adherent and visually free of blisters, pits, peeled areas, cracks, nodules, and unplated areas. B455 shall not be stained or discolored. Flow-brightened coatings shall be free of dewetted areas and beads.
All surfaces shall be substantially free of grease or oil used in the? When necessary, preliminary samples showing the?
Where a contact mark is inevitable, its location shall be subject to agreement between the supplier and the purchaser. The coating should adhere to satm basis metal when subjected to the agreed test;?
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?
The amount of porosity in the coating that may be tolerable depends on the severity of the environment that the article is likely to encounter during service or storage. If the pores are few in number, or away from signi? Such acceptance or pass-fail criteria, if required, should be part of the product speci? A thicker coating of nickel may astmm required in some situations for additional retardation. See Supplementary Requirements S1 and S2 for details. These articles the inspection lots are inspected and classi?
The size of the sample and the criteria of compliance are determined by the application of statistics. The procedure is known as sampling inspection. Three standards, Test Method BGuide Band Test Method Bcontain sampling plans that are designed for the sampling inspection of coatings. Test Method B contains four sampling plans, three for use with tests that are non-destructive and one for use when they are destructive.
The buyer and seller may agree on the plan or plans to be used.
MIL-T-10727 vs. ASTM B545
If they do not, Test Method B identi? Guide B provides a large number of plans and also provides guidance in the selection of a plan.
When Guide B is speci? Test Method B can be used only for coating requirements that have a numerical limit, such as coating thickness. The test must yield a numerical value, and certain statistical requirements must be met. Test Method B contains several plans and also provides instructions for calculating plans to asmt special needs.
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. Initial scanning should be conducted for all elements in order to detect any unknown or unexpected impurities. If special test specimens are used 7.
Practice B may be consulted to determine the most appropriate test method. When Test Method B is used astk measure these types of coatings, the measuring instrument shall be calibrated with thickness standards that have the same substrate and same composition of coating as the product. Also see Note 5. Three test methods are described in Appendix X3, while a simple dip test is given in Test Method B The purchaser shall specify whether the tested articles are to receive an arti?
Black spots or lines are evidence of mechanical damage or gross defects. Blackening at pores will be evidence of porosity.
Rejection and Rehearing 9. Rejection shall be reported to the seller promptly and in writing. In cases of rejection, the seller may make a claim for a rehearing. Product that shows coating imperfections in subsequent manufacturing operations may be rejected.
Government Packaging Requirements S4. Warning—Some contemporary packaging materials asm emit fumes that are deleterious to the surface of the coating. The number of articles shall be sufficient to have a total weight of coating of at least 0.
Calculate the coated area in mm2 to an accuracy of at least 1 part in Dry and weigh with an accuracy of at least 1 part in Remove h545 articles, rinse them in clean water, wipe and brush as necessary to remove smut antimony residuesand dry. A suitable burnishing implement is a copper or steel disk used edgewise and broadside. Maintain pressure sufficient to burnish the? Poor adhesion will b455 shown by the appearance of aastm loose blister that grows as rubbing is continued.
If the quality of the deposit is also poor, the blister may g545, and the plating will peel away from the basis metal. Poor adhesion will be shown if the coating blisters, cracks, or peels.
A bright coating completely covering the zstm The mandrel shall have a diameter equal to the thickness of the sample. Examination of 43 magni? Adtm tin coatings, especially of bright tin, may show? Visual examination, time of wetting, measurement of area astk spread, and calculation of spread values are used to assess solderability 1, 2.
The test piece is held in a clamp that extends from an arm directly over the solder bath.