Electroplating Specifications.
Electroplating specifications define the technical requirements, quality standards, thickness ranges, and performance criteria for plated coatings across industries. These specs guide manufacturers and electroplating suppliers in delivering consistent, reliable metal finishes that meet engineering, durability, and compliance needs.
- SAE AMS 2404
- SAE AMS 2413
- SAE AMS 2422
- SAE AMS 2425
- SAE AMS 2460
- SAE AMS 2465
- SAE AMS 2470
- SAE AMS 2481
- SAE AMS 2485
- SAE AMS 2490
- SAE AMS 2495
- SAE AMS 2500
- SAE AMS 2510
- SAE AMS 2520
- SAE AMS 2530
- SAE AMS 2540
- SAE AMS 2550
- SAE AMS 2560
- SAE AMS 2570
- SAE AMS 2580
- SAE AMS 2590
- SAE AMS 2600
- SAE AMS G 2418
- SAE AMS P 81728
- SAE AMS QQ N 290
- BMW GS90010
- Columbia Chemical GMW 4700 ZNNI Type B
- Cummins 74052
- Ford WSS M1P87 B5
- GM GMW4700
- Honda HES D2003 MFZN NI1 K
- Hyundai Kia MS611 15
- Jaguar Land Rover STJLR 50 5058
- Mazda MES CG310
- Mercedes DBL 8451
- Stellantis PS 50045
- Stellantis PS 50065
- Tesla TM 0009F M 10
- Toyota TSH6530G
- Toyota TSH6532G
- Volkswagen TL 244
- Volkswagen VW 4301
- Volkswagen VW 4320
- Volvo STD 121 0003
Solder Plating Standard: ASTM B579 covers tin-lead fluoborate coatings typically used for soldering applications in electronics manufacturing.
Summary
ASTM B579 deals with electrodeposited tin-lead alloy coatings from fluoborate bath chemistry. This is the "solder plate" specification for parts requiring soldering in electronics assembly. Fluoborate bath builds thick deposits quickly making it production favorite for circuit boards and electronic housings. Standard ensures alloy composition stays right for perfect melt typically focusing on eutectic or near-eutectic compositions flowing beautifully under soldering iron. Usage declining with RoHS restrictions but still referenced for military aerospace and legacy applications where lead solder remains technically superior and regulations permit.
Coatings
B579 covers tin-lead alloy electroplating from fluoborate baths for excellent solderability, moderate corrosion protection, and easy electronics assembly before lead-free regulations.
Requirements Overview
B579 defines service classes based on corrosion exposure and composition types for different tin-to-lead ratios. Class determines minimum thickness matching environment harshness. Type specifies alloy composition optimized for melting point and solderability. Most electronics used eutectic 60/40 composition at moderate thickness balancing solderability with corrosion protection and cost.
SC 2 (Moderate)
Minimum 8 microns. Standard for indoor electronics assemblies and circuit boards. Adequate corrosion protection for controlled environments.
SC 3 (Severe)
Minimum 15 microns. Outdoor electrical equipment exposed to weather. Telecommunications infrastructure, industrial controls requiring extended protection.
SC 4 (Very Severe)
Minimum 30 microns. Major corrosion protection in harsh environments. Offshore equipment, marine electronics, extreme exposure requiring thick solder coating.
60/40 Composition
60% tin, 40% lead. Eutectic alloy melting at 183C (361F). Standard electronics solder coating. Excellent flow characteristics, lowest melting point, optimal solderability for most applications.
63/37 Composition
63% tin, 37% lead. True eutectic solidifying at single temperature without pasty range. Wave soldering applications and automated assembly requiring instant solidification.
90/10 Composition
90% tin, 10% lead. High tin content for improved corrosion resistance. Components requiring enhanced protection with acceptable solderability for hand assembly operations.
Matte Finish
As-plated surface without reflow. Lower cost but solderability degrades during storage from oxidation. Immediate assembly applications where shelf life not concern.
Fused Finish
Reflowed coating briefly heated above melting point creating smooth bright surface. Extended solderability shelf life, better appearance, reduced porosity improving corrosion resistance. Standard for parts in storage.
Supplementary
Solderability testing, composition verification, whisker testing, or adhesion requirements added when application quality demands exceed base specification minimums.
Solder Coating Selection: Choosing composition and finish ensuring reliable solder joints in electronics assembly while managing lead regulations and shelf life requirements.
Requirements Selection
Verify lead solder acceptable before specifying B579 since RoHS and environmental regulations restrict commercial use. Military and aerospace applications justify eutectic 60/40 or 63/37 compositions for proven reliability. SC 2 thickness adequate for indoor electronics. SC 3 for outdoor equipment. Fused finish extends shelf life significantly versus matte for parts in storage before assembly. Now you'd consider lead-free alternatives unless exemptions allow traditional tin-lead proven over decades preventing tin whisker failures in critical applications.
Underplate Layer Stacks
Tin-lead from fluoborate baths plates directly onto copper or brass substrates for electronics without underplates. Excellent adhesion to copper base metals simplifies processing. Steel parts need copper underplate preventing iron contamination of solder coating affecting solderability. Nickel barrier sometimes used preventing copper diffusion through tin-lead over extended periods. Most commercial electronics used direct plating on copper for simplicity and cost. Aerospace applications added nickel barrier for long-term reliability insurance.
- Direct Plating: Tin-lead straight onto copper
Standard approach for copper or brass substrates in electronics manufacturing. Tin-lead from fluoborate bath adheres excellently to copper without intermediate layers. Cost effective for high-volume production where rapid assembly matters more than extended shelf life or extreme environments.
- Copper Underplate: Steel substrate barrier
Required on steel preventing iron contamination degrading tin-lead solder coating solderability. Typical 2.5 to 5 microns copper then tin-lead topcoat. Common on steel fasteners, brackets, and hardware requiring solder coating for assembly operations or corrosion protection.
- Nickel Barrier: Optional long-term protection
Used when copper diffusion through tin-lead causes long-term reliability concerns from intermetallic growth. Thin nickel layer between copper and solder coating slows diffusion. Aerospace and high-reliability military applications where extended service life justifies additional processing complexity and cost.
Solder Specification Errors: Common mistakes with tin-lead coatings causing regulatory violations, solderability failures, or discovering fluoborate residue eating parts from inside.
Common Mistakes
Ignoring fluoborate residue causing aggressive post-plate corrosion from trapped electrolyte in pores and crevices. Inadequate rinsing lets fluoborate eat parts from inside out over time. Specifying tin-lead without checking RoHS compliance creates European customs rejections and regulatory headaches. Using matte finish for parts in long-term storage causes solderability degradation from oxidation. Missing composition verification allows off-ratio deposits with wrong melting points ruining assembly operations.
Fluoborate Residue Corrosion
Fluoborate baths deposit aggressive electrolyte in coating porosity and part crevices. Inadequate rinsing leaves acidic residue causing internal corrosion from inside out. Always specify thorough multi-stage rinsing and neutralization. Fluoborate residue is specification oversight causing mysterious field failures months after plating.
Lead Regulatory Compliance Oversight
Specifying tin-lead without verifying RoHS and environmental compliance is career-limiting mistake. European markets ban lead in consumer electronics. Many U.S. states restrict lead too. Military and aerospace have exemptions but commercial products need lead-free coatings. Check applicable regulations before defaulting to traditional tin-lead.
Matte Finish for Long Storage
As-plated matte tin-lead oxidizes degrading solderability within months of storage. Parts sitting over six months before assembly absolutely need fused reflowed finish. Reflow melts coating creating bright smooth surface resisting oxidation dramatically. Extended shelf life justifies modest reflow cost preventing assembly failures.
Off-Ratio Composition Acceptance
B579 specifies tin-to-lead ratio tolerances but if you don't verify composition with XRF or chemical analysis, off-ratio deposits slip through. Wrong composition means wrong melting point ruining wave solder or reflow assembly. Composition verification supplementary requirement catches bath control problems before thousands of parts fail assembly.
Insufficient Thickness for Environment
SC2 minimum 8 microns barely adequate for indoor controlled environments. Outdoor exposure or humid conditions need SC3 or SC4 thickness. Thin coatings have inherent porosity allowing corrosion reaching substrate. The extra material cost is trivial compared to field failures from inadequate protection in actual service conditions.
Conclusion
ASTM B579 defined tin-lead fluoborate solder coatings during leaded solder dominance in electronics. Specification remains relevant for military aerospace and legacy applications where lead exemptions exist and proven reliability trumps environmental concerns. For commercial designs verify RoHS compliance before specifying. When tin-lead acceptable, eutectic compositions with fused finish provide optimal solderability and shelf life. Thorough rinsing mandatory preventing fluoborate residue corrosion. The spec's compositional flexibility addressed diverse needs from automated assembly to hand soldering.
Next Steps
Verify regulatory compliance before specifying tin-lead. Military and aerospace may justify traditional compositions. Commercial products need lead-free alternatives. If tin-lead acceptable, specify eutectic 60/40 or 63/37 for best solderability. Use fused finish for extended storage. Add solderability testing and composition verification for critical applications. Specify thorough rinsing preventing fluoborate residue corrosion. Work with electronics finishing specialists understanding both leaded and lead-free solder coating processes.