ISO 9453:2020

Overview

ISO 9453:2020 - Soft solder alloys - Chemical compositions and forms - defines chemical composition limits and typical product forms for soft solder alloys used to join metallic parts. The standard covers alloys that contain two or more of tin, lead, antimony, copper, silver, bismuth, zinc, indium and cadmium, and distinguishes between lead-containing and lead‑free alloy groups. It also provides guidance on sampling, analysis, marking, labelling and packaging.

Key topics and technical requirements

• Chemical compositions: Detailed mass‑fraction limits for alloy groups and individual alloys are given in Table 2 (lead‑containing) and Table 3 (lead‑free). Single‑figure impurity limits are maximum values; “Rem” denotes the remainder to 100 %.
• Alloy identification: Numeric alloy designations are listed; Annex A compares these with IEC short names (IEC 61190‑1‑3).
• Melting information: Solidus/liquidus temperatures are shown for information only and are not prescriptive requirements.
• Forms of delivery: Accepted product forms include ingots, slabs, sticks, bars, rods, wire, pellets, preforms, spheres, ribbons, powder, pastes and creams. Not all compositions are available in every form.
• Units of product: Marking and traceability requirements vary by form (e.g., single ingot vs. reel of wire vs. individually packaged paste).
• Sampling and analysis: Inductively coupled plasma (ICP) is the recommended analytical technique; Spark‑OES and AAS are acceptable with agreement between supplier and purchaser.
• Marking and packaging: Each batch must carry specified markings (see Table 4), including health/safety and lead‑free or lead‑containing indicators. Flux inclusion in rods/wire is by supplier–purchaser agreement.
• Regulatory notes: The document acknowledges possible patent assertions and collaboration with IEC/CEN technical committees.

Applications and who uses this standard

• Electronics OEMs and PCBA assemblers selecting solder alloys for wave, reflow or hand soldering.
• Solder manufacturers and formulators specifying product chemistry and product forms.
• Quality, procurement and compliance teams ensuring material traceability, labelling and conformity with chemical specifications.
• Test labs and inspectors using ICP, Spark‑OES or AAS methods for compositional verification.
• Engineers choosing between lead‑free and tin‑lead solders for reliability, process temperature and regulatory needs.

Related standards

• IEC 61190‑1‑3 (short alloy names and compositions) - compared in Annex A of ISO 9453:2020.
• ISO/TC 44 (Welding and allied processes) and CEN collaboration noted in the foreword.

ISO 9453 is a practical reference for anyone involved in specification, production, testing or procurement of soft solder alloys, helping ensure consistent chemistry, correct product forms and proper marking for manufacturing and regulatory compliance.