IEC 60749-20:2020

Overview - IEC 60749-20:2020 (Resistance of plastic encapsulated SMDs to moisture and soldering heat)

IEC 60749-20:2020 is the International Electrotechnical Commission standard that defines a destructive test method to assess the resistance to soldering heat of plastic‑encapsulated surface‑mount devices (SMDs) when they are exposed to the combined effects of moisture and soldering heat. The third edition (2020) updates the previous edition by incorporating a technical corrigendum, adding a new Clause 3 (terms and definitions), and including explanatory notes to improve clarity.

Key topics and technical requirements

• Scope and applicability: Applies to plastic‑encapsulated, non‑hermetic SMDs; used as a precondition or qualification test before reliability evaluation.
• Test flow: Initial inspections and electrical measurements → drying → controlled moisture soak → exposure to soldering heat → recovery → final inspections and measurements.
• Test apparatus and materials: Humidity chamber, reflow/infrared/convective soldering equipment, vapour‑phase and wave‑soldering apparatus, holders, solvents, fluxes and solder materials.
• Moisture soak conditions: Standardized moisture soak regimes (including common soak conditions such as 85 °C/85 % RH shown in annex) and methods for dry‑packed versus non‑dry‑packed SMDs to achieve representative internal moisture levels.
• Soldering heat methods: Classification reflow profiles for Sn–Pb and Pb‑free processes, vapour‑phase reflow and wave‑soldering immersion methods. The standard defines how to measure and report specimen temperature profiles.
• Measurements and inspection: Visual and electrical checks plus acoustic tomography (acoustic microscopy) for internal inspection both before and after testing.
• Destructive nature: The test is explicitly destructive; failure modes and acceptance criteria are defined in the relevant product specification.

Practical applications and who uses IEC 60749-20:2020

• Semiconductor manufacturers - to qualify packages against moisture‑induced soldering failures (popcorning, delamination, cracking).
• Reliability and qualification engineers - to design preconditioning and stress tests before reliability testing.
• Contract manufacturers and PCB assemblers - to validate soldering processes and reflow/wave profiles relative to moisture sensitivity.
• Test labs and compliance bodies - to perform standardized destructive assessments and generate repeatable data for product datasheets and supplier agreements.
• OEMs and procurement - to specify component requirements and ensure components meet assembly thermal‑moisture resilience.

Related standards

• IEC 60068-2-20 (solderability / resistance to soldering heat)
• IEC 60749-3 (visual inspection)
• IEC 60749-30 (preconditioning of non‑hermetic SMDs)
• IEC 60749-35 (acoustic microscopy for plastic encapsulated components)

Keywords: IEC 60749-20:2020, resistance to soldering heat, plastic encapsulated SMDs, moisture soak, reflow soldering, vapour‑phase, wave‑soldering, acoustic tomography, moisture sensitivity, preconditioning.