1.1 This specification covers the requirements for electrodeposited tin-lead coatings on fabricated articles of iron, steel, copper, and copper alloys, to protect them against corrosion (Note 1), to improve and preserve solderability over long periods of storage, and to improve anti-galling characteristics. NOTE 1—Some corrosion of tin-lead coatings may be expected in outdoor exposure. In normal indoor exposure, tin-lead is protective on iron, copper, and copper alloys. Corrosion may be expected at discontinuities (pits or pores) in the coating. Porosity decreases as the thickness is increased. A primary use of the tin-lead coating (solder) is with the printed circuit industry as a solderable coating and as an etch mask material.
1.2 This specification applies to electrodeposited coatings containing a minimum of 50 % and a maximum of 70 % tin. The specification applies to mat, bright, and flow-brightened tin-lead coatings. NOTE 2—Tin-lead plating baths are composed of tin and lead fluoborates and of addition agents to promote stability. The final appearance may be influenced by the addition of proprietary brighteners. Without brighteners, the coatings are mat; with brighteners, they are semibright or bright. Flow-brightened coatings are obtained by heating mat coatings to above the melting point of tin-lead for a few seconds and then quenching; palm oil, hydrogenated oils, or fats are used as a heat-transfer medium at a temperature of 260 6 10 °C (500 6 20 °F), but other methods of heating are also in use. The maximum thickness for flow-brightening is about
7.5 µm (0.3 mil); thicker coatings tend to reflow unevenly. The shape of the part is also a factor; flat surfaces tend to reflow more unevenly than wires or rounded shapes (Note 3). NOTE 3—Volatile impurities in tin-lead coatings will cause bubbling and foaming during flow-brightening resulting in voids and roughness. The impurities can arise from plating solution addition agents and from improper rinsing and processing.
1.3 This specification does not apply to sheet, strip, or wire in the unfabricated form or to threaded articles having basic major diameters up to and including 19 mm (0.75 in.).
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
ASTM B579-22 Referenced Document
ASTM B183 Standard Practice for Preparation of Low-Carbon Steel for Electroplating
ASTM B242 Standard Guide for Preparation of High-Carbon Steel for Electroplating
ASTM B281 Standard Practice for Preparation of Copper and Copper-Base Alloys for Electroplating and Conversion Coatings
ASTM B322 Standard Guide for Cleaning Metals Prior to Electroplating
ASTM B487 Standard Test Method for Measurement of Metal and Oxide Coating Thickness by Microscopical Examination of Cross Section
ASTM B499 Standard Test Method for Measurement of Coating Thicknesses by the Magnetic Method: Nonmagnetic Coatings on Magnetic Basis Metals
ASTM B504 Standard Test Method for Measurement of Thickness of Metallic Coatings by the Coulometric Method*, 2023-05-01 Update
ASTM B567 Standard Test Method for Measurement of Coating Thickness by the Beta Backscatter Method*, 2024-04-22 Update
ASTM B568 Standard Test Method for Measurement of Coating Thickness by X-Ray Spectrometry
ASTM B849 Standard Specification for Pre-Treatments of Iron or Steel for Reducing Risk of Hydrogen Embrittlement
ASTM B850 Standard Guide for Post-Coating Treatments of Steel for Reducing the Risk of Hydrogen Embrittlement
ASTM E105 Standard Practice for Probability Sampling Of Materials*, 2024-04-22 Update
ASTM E122 Standard Practice for Calculating Sample Size to Estimate, With a Specified Tolerable Error, the Average for Characteristic of a Lot or Process
ASTM B579-22 history
2022ASTM B579-22 Standard Specification for Electrodeposited Coatings of Tin-Lead Alloy (Solder Plate)
2015ASTM B579-73(2015) Standard Specification for Electrodeposited Coatings of Tin-Lead Alloy (Solder Plate)
1973ASTM B579-73(2009) Standard Specification for Electrodeposited Coatings of Tin-Lead Alloy (Solder Plate)
1973ASTM B579-73(2004) Standard Specification for Electrodeposited Coatings of Tin-Lead Alloy (Solder Plate)
1973ASTM B579-73(1999) Standard Specification for Electrodeposited Coatings of Tin-Lead Alloy (Solder Plate)