IEC 60068-2-21:2006

Overview

IEC 60068-2-21:2006 is an international environmental testing standard that specifies Test U: Robustness of terminations and integral mounting devices. It applies to electrical and electronic components whose terminations or mounting features may be exposed to mechanical stresses during normal assembly or handling. This sixth edition (with the January 2012 corrigendum included) is part of the IEC 60068 series on environmental testing.

Key topics and requirements

• Scope and applicability: Covers both leaded and surface-mounted devices (SMD) for stresses encountered in assembly/handling. Table 1 in the standard maps tests to component types and mounted/unmounted states.
• Defined mechanical tests:
  • Ua (Tensile and Thrust) – axial forces on leaded terminations.
  • Ub (Bending) – bending of leaded terminations.
  • Uc (Torsion) – torsional stresses on wire terminations.
  • Ud (Torque) – torque on threaded studs or screw terminations.
  • Ue (Robustness of SMD terminations in the mounted state) – includes bending (Ue1), pull/push (Ue2), and shear/adhesion (Ue3) subtests.
• Notable technical changes in this edition:
  • Addition of torque severity for nominal thread diameter 8 mm (Ud) referencing IEC 60252‑2.
  • Substrate specification and mounting updated to describe lead‑free solder for Ue.
  • Modified test jig and substrate bending conditions for Ue1 (see Figure 7).
  • Shear test (Ue3) pushing force changed from 10 N to 5 N.
• Preconditioning, measurement and pass/fail criteria: Each test defines preconditioning, initial/final measurements and information required in component specifications (see clauses 3–8).

Applications and users

• Who uses it:
  • Component manufacturers (leaded and SMD parts)
  • PCB assemblers and contract manufacturers
  • Design engineers specifying mechanical robustness requirements
  • Test labs performing component qualification
• Practical uses:
  • Specifying and validating termination strength and mounting reliability during product design and supplier qualification
  • Assessing durability of SMD joints (including lead‑free soldering processes)
  • Ensuring assemblies withstand handling, insertion, and fastening operations in manufacturing and field service

Related standards

• IEC 60068-1 (general guidance on environmental testing)
• IEC 60068-2-58 (solderability and resistance to dissolution for SMD)
• IEC 61190-1-2, IEC 61191-2 (soldering and assembly requirements)
• IEC 61249-2-7 (printed board materials)
• ISO 272, ISO 9453 (fastener and solder alloy references)

Keywords: IEC 60068-2-21, environmental testing standard, robustness of terminations, integral mounting devices, SMD robustness, lead-free solder, substrate bending, shear test, torque severity, assembly stresses.