IEC 60068-2-20:2008

Overview

IEC 60068-2-20:2008 (Test T) is an international environmental test standard that defines solderability and resistance to soldering heat test methods for electronic devices with leads (through‑hole and leaded components). It specifies laboratory procedures to determine whether component leads and terminations will wet properly with solder alloys (eutectic/near‑eutectic tin‑lead or lead‑free solder) and whether component bodies can withstand the thermal load during soldering. The standard covers two principal test methods: the solder bath method and the soldering iron method.

Key Topics and Requirements

• Scope and objective
  • Ensures component lead/termination solderability meets solder joint requirements referenced in IEC 61191‑3 and IEC 61191‑4.
  • Verifies component body resistance to soldering heat.
• Test types
  • Test Ta - Solderability: assesses wettability of wire and tag terminations using solder bath or soldering iron.
  • Test Tb - Resistance to soldering heat: evaluates the ability of the device body and leads to tolerate soldering temperatures without damage or unacceptable changes.
• Methods
  • Solder bath method (simulates flow/wave soldering): defined bath composition, temperature, exposure times, fluxing and measurement/acceptance criteria.
  • Soldering iron method (localized heating; used when bath method is impracticable): includes specified iron temperature (e.g., 350 °C for some procedures), solder/flux guidance and handling.
• Aging and conditioning
  • Optional accelerated ageing procedures prior to testing (steam ageing, damp heat, dry heat, pressurized vapour) to simulate storage or prior environmental exposure.
• Lead‑free support
  • Fifth edition adds test conditions and requirements for lead‑free solders and removes the solder globule test.
• Measurements and failure modes
  • Definitions and assessment of wetting, non‑wetting, and de‑wetting (retraction of molten solder), plus final inspection/acceptance criteria.

Applications and Who Uses It

• Intended for component manufacturers, test laboratories, quality/qualification engineers, and PCB assembly/process engineers who need to:
  • Validate solderability of leaded components for through‑hole and terminal soldered assemblies.
  • Qualify components for lead‑free assembly processes.
  • Define supplier test requirements in component specifications and procurement.
• Practical use cases include incoming inspection, design verification, reliability qualification, and process change assessment for soldering operations.

Related Standards

• IEC 61191‑3 / IEC 61191‑4 - Solder joint requirements for through‑hole and terminal assemblies
• IEC 60068‑2‑58 - Solderability tests for SMDs
• IEC 60068‑2‑54, IEC 60068‑2‑69 - Wetting/wetting‑balance and SMD methods (informative references)
• IEC 60068‑1 - General guidance on environmental testing

Keywords: IEC 60068-2-20:2008, Test T, solderability, resistance to soldering heat, solder bath method, soldering iron method, lead-free solder, devices with leads, component qualification, solder joint requirements.