A test strategy in hardware development defines the overarching principles, responsibilities, methods, and evidence used to ensure that electronic and mechatronic systems meet requirements for functionality, safety, reliability, and compliance across the product lifecycle. It provides the long-term quality framework for design, validation, and production, integrating test levels and methods, industry standards, and measurable quality
Standards and Process Frameworks
- Functional safety: IEC 61508 (generic) and ISO 26262 (automotive), structured around ASIL levels (A–D), with higher rigor and test depth at higher safety levels (e.g., fault injection, coverage analysis).
- Industry-specific standards: DO-160 (aviation environmental tests), IEC 60601 (medical devices), EN 5012x (rail).
- Process frameworks: Automotive SPICE, especially HWE.4 (Hardware Test), requiring systematic planning, execution, and traceability of hardware tests.
Test Levels and Types
- Board-level: In-Circuit Testing (ICT), Flying Probe, Boundary Scan (IEEE 1149.1/JTAG).
- Subsystem/component level: Functional testing, EMC/ESD, thermal/vibration/humidity stress.
- System-level: Hardware-in-the-Loop (HIL), integration testbeds (e.g., “Iron Bird” in aerospace), end-of-line (EOL) testing in production.
- Reliability/robustness: HALT (development, design stress testing), HASS (production, process defect screening).
Methods – Clear Differentiation
- HALT/HASS:
- HALT during development: apply combined stress (thermal cycles, multi-axis vibration, voltage variation) well beyond spec limits to expose design weaknesses early.
- HASS in production: apply stress below damage thresholds (established by HALT) to identify process-related faults.
- In-Circuit Test (ICT): structural/component-level testing of populated PCBs (shorts, opens, component values). It does not verify full functional behavior.
- Boundary Scan (JTAG): interconnect test without physical access; essential for dense layouts (BGA). Often combined with ICT.
- Simulation & Digital Twin: virtual models for early verification (thermal, electrical, mechanical). The Digital Twin provides a real-time model of the physical system and can feed HIL setups. HIL uses models but is not equivalent to a Digital Twin.
Production and End-of-Line Testing
- Design for Testability (DfT): include test points, programming paths, diagnostic access.
- Throughput vs. coverage: balance test depth and takt time; may use sample-based extended testing.
- Pre-compliance: run in-house EMC or safety pre-tests to avoid costly failures in accredited labs.
Challenges
- Time-to-market: long validation cycles vs. market pressure → mitigated with simulation, rapid prototyping, early HIL.
- Safety/regulation: extensive evidence and re-verification on changes.
- Scaling: automated test execution, data analytics, yield tracking in high-volume production.
- Change management: regression logic for hardware tests (which tests to repeat after design updates).
Examples
Automotive: ADAS ECU validated via model-based testing, HIL with sensor simulation, integrated vehicle bus testing, field trials; ISO 26262 compliance with V&V traceability.
Medical devices: infusion pump tested for lifetime, IEC 60601 electrical safety, IEC 62304 software validation, usability tests; fault injection for safe-state behavior.
Aerospace: “Iron Bird” integration rigs for hydraulics, avionics, electrics; DO-160 environmental tests; flight readiness proven before actual flight tests.
Education & Certification
- Academic: Electrical engineering, mechatronics, computer engineering, with specialization in embedded systems or reliability engineering.
- Certifications: Functional Safety Engineer (ISO 26262/IEC 61508), Certified Reliability Engineer (CRE), Automotive SPICE assessor.
- Practical trainings: HIL development, ICT/Boundary Scan design, EMC pre-compliance.
Best Practices
- Early DfT, robust test architecture across levels, reproducible stress tests, closed-loop feedback of test data into design.
- Risk-based prioritization (criticality × probability × detectability).
- Shared V&V roadmap with software/mechanics to align mechatronic systems.
CALADE Perspective
CALADE combines regulatory expertise with pragmatic practices (DfT, HALT/HASS, HIL). We coach teams to balance shorter validation cycles with robust compliance, ensuring test architectures are both efficient and resilient.
Related Terms
- DfT
- HIL
- EMC
- Boundary Scan
- HALT/HASS
- End-of-Line Test
- Functional Safety
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