ASTM B579-22

Standard Specification for Electrodeposited Coatings of Tin-Lead Alloy (Solder Plate)

ABSTRACT
This specification establishes the requirements for mat, bright, and flow-brightened electrodeposited tin-lead alloy coatings on fabricated articles of iron, steel, copper, and copper alloys to protect them against corrosion, to improve and preserve solderability over long periods of storage, and to improve anti-galling characteristics. Sheets, strips, or wires in the unfabricated form, or threaded articles having a specified diameter, are not covered here. The classification notation shall include the type of basis metal, thickness of tin-lead coating required, service condition number indicating the severity of service required, and coating composition. Coatings shall be sampled, tested, and shall conform accordingly to specified requirements as to composition, appearance, thickness, adhesion (to be examined either by burnishing test, quenching test, reflow test, or bend test), and solderability (to be assessed either by non-automated or automated dip test, spread test, globule test, or artificial aging test).
SCOPE
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 ± 10 °C (500 ± 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.

General Information

• Status: Published
• Publication Date: 30-Apr-2022
• ICS: 25.220.40 - Metallic coatings
• Technical Committee: B08 - Metallic and Inorganic Coatings
• Drafting Committee: B08.06 - Soft Metals

Standards Content (Sample)

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.
Designation: B579 −22
Standard Specification for
1
Electrodeposited Coatings of Tin-Lead Alloy (Solder Plate)
This standard is issued under the fixed designation B579; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
1.1 Thisspecificationcoverstherequirementsforelectrode-
1.5 This international standard was developed in accor-
posited tin-lead coatings on fabricated articles of iron, steel,
dance with internationally recognized principles on standard-
copper, and copper alloys, to protect them against corrosion
ization established in the Decision on Principles for the
(Note 1), to improve and preserve solderability over long
Development of International Standards, Guides and Recom-
periods of storage, and to improve anti-galling characteristics.
mendations issued by the World Trade Organization Technical
NOTE 1—Some corrosion of tin-lead coatings may be expected in
Barriers to Trade (TBT) Committee.
outdoor exposure. In normal indoor exposure, tin-lead is protective on
iron, copper, and copper alloys. Corrosion may be expected at disconti-
2. Referenced Documents
nuities(pitsorpores)inthecoating.Porositydecreasesasthethicknessis
2
increased.Aprimaryuseofthetin-leadcoating(solder)iswiththeprinted 2.1 ASTM Standards:
circuit industry as a solderable coating and as an etch mask material.
B183Practice for Preparation of Low-Carbon Steel for
Electroplating
1.2 This specification applies to electrodeposited coatings
B242Guide for Preparation of High-Carbon Steel for Elec-
containing a minimum of 50% and a maximum of 70% tin.
troplating
The specification applies to mat, bright, and flow-brightened
B281Practice for Preparation of Copper and Copper-Base
tin-lead coatings.
Alloys for Electroplating and Conversion Coatings
NOTE 2—Tin-lead plating baths are composed of tin and lead fluobo-
B322Guide for Cleaning Metals Prior to Electroplating
ratesandofadditionagentstopromotestability.Thefinalappearancemay
B487Test Method for Measurement of Metal and Oxide
be influenced by the addition of proprietary brighteners. Without
brighteners, the coatings are mat; with brighteners, they are semibright or Coating Thickness by Microscopical Examination of
bright. Flow-brightened coatings are obtained by heating mat coatings to
Cross Section
abovethemeltingpointoftin-leadforafewsecondsandthenquenching;
B499Test Method for Measurement of CoatingThicknesses
palm oil, hydrogenated oils, or fats are used as a heat-transfer medium at
by the Magnetic Method: Nonmagnetic Coatings on
atemperatureof260 610°C(500 620°F),butothermethodsofheating
Magnetic Basis Metals
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
B504Test Method for Measurement of Thickness of Metal-
part is also a factor; flat surfaces tend to reflow more unevenly than wires
lic Coatings by the Coulometric Method
or rounded shapes (Note 3).
B567Test Method for Measurement of Coating Thickness
NOTE 3—Volatile impurities in tin-lead coatings will cause bubbling
by the Beta Backscatter Method
and foaming during flow-brightening resulting in voids and roughness.
The impurities can arise from plating solution addition agents and from B568Test Method for Measurement of Coating Thickness
improper rinsing and processing.
by X-Ray Spectrometry
B849Specification for Pre-Treatments of Iron or Steel for
1.3 This specification does not apply to sheet, strip, or wire
Reducing Risk of Hydrogen Embrittlement
in the unfabricated form or to threaded articles having basic
B850GuideforPost-CoatingTreatmentsofSteelforReduc-
major diameters up to and including 19mm (0.75in.).
ing the Risk of Hydrogen Embrittlement
1.4 This standard does not purport to address all of the
E105Guide for Probability Sampling of Materials
safety concerns, if any, associated with its use. It is the
E122PracticeforCalculatingSampleSizetoEstimate,With
responsibility of the user of this standard to establish appro-
Specified Precision, the Average for a Characteristic of a
Lot or Process
1
This specification is under the jurisdiction of ASTM Committee B08 on
Metallic and Inorganic Coatings and is the direct responsibility of Subcommittee
2
B08.06 on Soft Metals. Fo
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: B579 − 73 (Reapproved 2015) B579 − 22
Standard Specification for
1
Electrodeposited Coatings of Tin-Lead Alloy (Solder Plate)
This standard is issued under the fixed designation B579; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope
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°C10 °C (500 6 20°F),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.).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.
1
This specification is under the jurisdiction of ASTM Committee B08 on Metallic and Inorganic Coatings and is the direct responsibility of Subcommittee B08.06 on Soft
Metals.
Current edition approved March 1, 2015May 1, 2022. Published April 2015May 2022. Originally approved in 1973. Last previous edition approved in 20092015 as
B579B579 – 73–73 (2009).(2015). DOI: 10.1520/B0579-73R15.10.1520/B0579-22.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

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B579 − 22
2. Referenced Documents
2
2.1 ASTM Standards:
B183 Practice for Preparation of Low-Carbon Steel for Electroplating
B242 Guide for Preparation of High-Carbon Steel for Electroplating
B281 Practice for Preparation of Copper and Copper-Base Alloys for Electroplating and Conversion Coatings
B322 Guide for Cleaning Metals Prior to Electroplating
B487 Test Method for Measurement of Metal and Oxide Coating Thickness by Microscopical Examination of Cross Section
B499 Test Method for Measurement of Coating Thicknesses by the Magnetic Method: Nonmag
...