Overview
IEC 62435-2:2017 is an international standard developed by the International Electrotechnical Commission (IEC) focused on the long-term storage of electronic semiconductor devices. Specifically, Part 2 of this series addresses the deterioration mechanisms that occur in electronic components during extended storage periods, typically beyond 12 months. The standard provides essential guidance on identifying, understanding, and mitigating the factors that contribute to the degradation of semiconductor devices over time under various storage conditions.
This standard is highly relevant for industries that rely on the longevity and reliability of electronic components, such as aerospace, railways, energy sectors, and other fields where equipment operational life can span decades. It should be used in conjunction with IEC 62435-1:2017 for a comprehensive approach to long-term storage.
Key Topics
Deterioration Mechanisms
IEC 62435-2 outlines the primary mechanisms by which electronic semiconductor devices degrade over time, including:
- Solderability and oxidation of lead finishes: Oxidation can reduce the solderability of device leads, affecting assembly and functionality.
- Popcorning: Moisture-induced internal damage caused by vapor expansion during soldering processes.
- Delamination: Separation between layers within packaged components that compromises mechanical integrity.
- Corrosion and tarnishing: Environmental factors causing chemical degradation of conductive materials.
- Electrical effects: Changes in electrical properties due to storage stress.
- High-energy ionizing radiation damage: Potential effects of radiation on semiconductor devices during storage.
- Storage temperature risks: The impact of temperature extremes on device reliability.
- Finish-related issues: Differences in degradation between noble metal finishes, matte tin, solder bumps, and solder balls.
- Programming memory retention: Considerations for devices with non-volatile or programmable memory that may lose data over time.
Test Methods and Technical Validation
The standard provides guidance on test methods to assess generic deterioration due to storage conditions, including:
- Reliability assessment of batches during storage.
- Selection criteria for relevant tests tailored to device type and storage environment.
- Periodic reevaluation procedures to ensure continued device viability.
A detailed list of test methods assists manufacturers and users in validating long-term storage effectiveness.
Storage Practices
IEC 62435-2 emphasizes the importance of mastering storage processes and environments, highlighting:
- The critical role of humidity, temperature stability, electrostatic discharge (ESD) control, and contamination prevention.
- The necessity to store devices in conditions minimizing moisture, UV exposure, and air-borne contaminants.
- The particular needs for moisture-sensitive devices and the relevance of referring to related standards like IEC TR 62258-3 for short-term moisture protection.
Applications
Industries and applications benefiting from IEC 62435-2:2017 include:
- Aerospace and defense: Ensuring that highly reliable semiconductor devices remain functional over multi-decade life spans.
- Rail transport and energy sectors: Supporting maintenance, repair, and overhaul operations where components must be stocked long-term.
- Manufacturing and production planning: Enabling lifetime buys and stockpiling of electronic parts to mitigate obsolescence risks.
- Repair and warranty services: Storing spare parts effectively to support legacy systems over extended periods.
- Quality assurance and compliance: Establishing standardized methods to evaluate stored components for future use.
By adhering to the guidelines in IEC 62435-2, manufacturers, distributors, and end-users can reduce the technical risks associated with long-term storage and increase the reliability of stored semiconductor devices.
Related Standards
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IEC 62435-1:2017 - Electronic components - Long-term storage of electronic semiconductor devices - Part 1: Storage planning and practices
Provides overarching storage planning, handling, and storage environment requirements to be used in conjunction with Part 2.
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IEC TR 62258-3 - Handling and storage of moisture-sensitive devices - Part 3: Guidelines for storage of moisture sensitive devices for shorter durations
Addresses moisture-sensitive components stored for less than 12 months, complementing IEC 62435-2's focus on longer duration storage.
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IEC 60749 series - Semiconductor device reliability test methods
Standardizes reliability tests relevant for the assessment of components pre- and post-storage.
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ISO/IEC Directives, Part 2 - Rules for the structure and drafting of International Standards
Framework followed during the drafting and revision of IEC 62435-2 to maintain consistency.
By following the IEC 62435-2:2017 standard, organizations can effectively control and predict the deterioration mechanisms affecting semiconductor devices during long-term storage, helping ensure device performance and operational readiness when deployed after extended storage periods. Proper implementation supports improved lifecycle management, cost savings, and operational reliability across critical sectors.