Overview
IEC 62047-21:2014 is an international standard published by the International Electrotechnical Commission (IEC) that specifies a precise test method for determining Poisson's ratio of thin film micro-electromechanical systems (MEMS) materials. Poisson's ratio is a critical mechanical property that reflects the ratio of transverse strain to longitudinal strain when a material is subjected to stress. This standard applies specifically to thin-film MEMS materials with dimensions less than 10 mm in length and width, and thicknesses under 10 μm.
The standard details two types of test pieces and testing procedures involving uniaxial and biaxial loading. This enables manufacturers, researchers, and quality control engineers to accurately assess the mechanical behavior of MEMS thin films-essential for device reliability and performance optimization.
Key Topics
- Test Scope: Focuses on thin film MEMS materials with dimensions under 10 mm length/width and thickness below 10 µm.
- Poisson’s Ratio Definition: Ratio of transverse strain to longitudinal strain under elastic deformation, expressed as negative transverse strain divided by longitudinal strain.
- Test Piece Types:
- Type 1: Tensile specimen shape with gauge markers for longitudinal and transverse strain measurement.
- Type 2: Test piece containing circular and rectangular membranes to avoid measurement errors due to wrinkling or out-of-plane deformation.
- Test Procedures:
- Application of uniaxial load on Type 1 test pieces.
- Application of biaxial load through membrane bulging on Type 2 test pieces.
- Test Environment: Conditions such as temperature and loading rate are controlled to maintain consistent results.
- Measurement Techniques: Use of optical strain measurement methods, including digital image correlation (DIC) for accurate strain calculation.
- Data Analysis: Involves evaluating stress and strain distributions and calculating Poisson's ratio from measured strains.
Applications
IEC 62047-21:2014 serves as a vital guideline for multiple sectors working with MEMS and thin film materials:
- MEMS Device Manufacturing: Ensures mechanical properties of thin films meet design specifications for sensors, actuators, and microstructures.
- Material Research and Development: Enables researchers to characterize new thin film materials under standard conditions.
- Quality Control and Reliability Testing: Provides repeatable test methods to verify consistency in Poisson's ratio, assisting in predicting device robustness.
- Microelectronics Industry: Supports development of semiconductor devices with thin film layers by providing reliable mechanical property data.
- Academic and Industrial Laboratories: Facilitates comparative studies and material selection using standardized testing approaches.
By helping industries obtain accurate mechanical parameters, this standard contributes to the advancement and reliability of micro-electromechanical systems.
Related Standards
IEC 62047-21:2014 references and relates to other significant standards in the MEMS and thin film materials testing domain:
- IEC 62047-8:2011 – Strip bending test method for tensile property measurement of thin films, complementary for obtaining Young's modulus and breaking strength.
- ASTM E132-04:2010 – Standard test method for Poisson's ratio at room temperature, offering additional methods applicable to general materials.
- General IEC 62047 series, which addresses various testing and measurement standards for micro-electromechanical devices.
These documents collectively provide a comprehensive framework for evaluating mechanical properties of thin film semiconductor and MEMS components, ensuring global harmonization and reliability.
Keywords: IEC 62047-21, Poisson’s ratio, thin film MEMS materials, micro-electromechanical systems, MEMS testing, semiconductor devices, uniaxial and biaxial loading, microfabrication, mechanical property measurement, membrane bulging, tensile test, digital image correlation, thin film mechanical properties.
Open preview (PDF)Semiconductor devices - Micro-electromechanical devices - Part 21: Test method for Poisson's ratio of thin film MEMS materials
