Overview
IEC 60749-5:2017 specifies a steady‑state temperature and humidity bias life test for evaluating the reliability of non‑hermetic packaged solid‑state (semiconductor) devices in humid environments. This second edition (2017) updates the first edition (2003) and is a technical revision that corrects an equation, adds guidance notes, and clarifies applicable test conditions. The method is considered destructive and is intended to accelerate moisture‑related failure mechanisms that occur through encapsulants or along interfaces.
Key topics and requirements
- Test objective: Accelerate and detect moisture‑induced failure modes in plastic or other non‑hermetic packages under temperature, humidity and electrical bias.
- Environmental conditions: Steady‑state temperature and relative humidity conditions (the standard gives specific temperature/RH test points, e.g., the commonly used 85 °C / 85 % RH case is discussed).
- Biasing guidelines:
- Minimize power dissipation; alternate pin bias; distribute potential differences across metallization; maximize voltage within the device operating range.
- Two bias regimes: continuous bias and cycled bias (cycled bias often cited as 1 h on / 1 h off for many plastic‑encapsulated microcircuits). Choice depends on junction temperature and power dissipation; the standard requires reporting virtual junction temperature when it exceeds ambient by specified limits.
- Equipment and setup: Temperature‑humidity chamber with electrical feedthroughs; devices placed to minimize temperature gradients; care to avoid ionic contamination and materials that release contaminants; use of deionized water as specified by the standard.
- Procedures and reporting: Mounting, ramp‑up/ramp‑down, readouts, failure criteria and handling are defined; virtual junction temperature calculations and their reporting are required when applicable.
- Relation to HAST: Results from this steady‑state humidity bias test take priority over HAST (IEC 60749‑4) when both are performed, as HAST is an accelerated alternative for similar mechanisms.
Applications and users
- Reliability engineers and qualification teams in semiconductor manufacturing and component suppliers
- Test laboratories and OEMs performing environmental qualification of non‑hermetic devices (automotive, industrial, consumer electronics, medical)
- Purchase/quality assurance groups requiring moisture resistance evidence for design validation and supplier qualification
Practical uses include lifetime and margin assessments, failure analysis, and verification of packaging/process improvements against moisture ingress.
Related standards
- IEC 60749-4 - Damp heat, steady‑state, highly accelerated stress test (HAST): complementary/alternate accelerated moisture test referenced by IEC 60749‑5.
Keywords: IEC 60749-5:2017, steady‑state temperature humidity bias life test, semiconductor reliability test, non‑hermetic package, 85°C/85% RH, biasing guidelines, HAST, virtual junction temperature, ionic contamination.