Overview
ISO 2093:1986 - Electroplated coatings of tin - Specification and test methods - defines requirements and test methods for electroplated, nominally pure tin coatings on fabricated metal articles. The standard covers both dull and bright electroplated tin and flow-melted (reflowed) finishes and is intended to ensure corrosion protection and solderability of components. It excludes threaded parts, tin‑coated copper wire, semi‑finished strip/sheet/wire, coil springs, chemically applied (electroless) tin, and electroplating on very high‑strength steels (>1 000 MPa).
Key Topics and Requirements
- Scope & exclusions: Clear boundaries for applicability (fabricated articles only; not for electroless coatings or very high‑strength steels).
- Purchaser-supplied information: The purchaser must specify the ISO number, basis material, service condition number (1–4), coating classification code, significant surfaces, sampling plan, acceptable defect locations, adhesion test method and any special treatments or undercoat requirements.
- Coating classification code: Four-part code (basis metal/undercoat thickness tin thickness/finish). Example: Fe/Ni 2,5 Sn 5 f (steel with 2.5 µm Ni undercoat, 5 µm Sn, flow-melted).
- Thickness requirements: Minimum tin thicknesses by service condition and substrate:
- Service 4: Sn 30 µm (copper and other materials)
- Service 3: Sn 15 µm (copper), Sn 20 µm (others)
- Service 2: Sn 8 µm (copper), Sn 12 µm (others)
- Service 1: Sn 5 µm (all)
- Undercoats: Required in some cases (e.g., topper alloys with zinc - recommended Ni/topper undercoat ≥ 2.5 µm).
- Heat treatment / hydrogen embrittlement: Stress relief before plating for cold‑worked steels (1 h at 190–220 °C); alternative lower‑temperature stress relief for carburized/hardened parts (e.g., 130–150 °C for ≥5 h). Post‑plating hydrogen embrittlement relief is generally impractical for tin.
- Appearance, adhesion, porosity, solderability: Visual appearance criteria; adhesion testing methods (Annex B); porosity testing (ISO 3768 for ferrous, ISO 6988 for non‑ferrous); solderability per IEC 68‑2‑20 test methods.
Applications and Users
ISO 2093 is used by:
- Plating shops and electroplaters specifying process controls and documentation
- OEMs and buyers of plated components who require defined corrosion protection and solderability
- PCB manufacturers for through‑hole tin plating specifications
- Quality engineers, inspectors and laboratories performing thickness, adhesion and porosity testing
Key applications include electronic components, connectors and general-purpose plated metal parts where tin plating is required for corrosion protection or solderability.
Related Standards
Referenced standards include ISO 1463, ISO 2064, ISO 2177, ISO 2859, ISO 3497, ISO 3543, ISO 3768, ISO 6988 and IEC Publication 68‑2‑20 (solderability tests). These provide the test methods (microscopy, coulometric, X‑ray, beta backscatter) and sampling procedures used with ISO 2093.
