Overview
IEC TR 61189-3-914:2017 is an International Electrotechnical Commission (IEC) Technical Report that specifies detailed procedures and precautions for measuring the thermal conductivity of printed circuit boards (PCBs) used in high-brightness LEDs. As a supplement to IEC 61189-3-913, this guideline ensures reliable thermal performance testing, which is essential for the optimal function and longevity of electronic assemblies where heat dissipation is a critical factor. The standard is intended for manufacturers, testing laboratories, and quality assurance teams involved with electrical materials, printed boards, and interconnection assemblies.
Key Topics
- Thermal Conductivity Measurement: The guideline provides defined approaches for measuring both in-plane and through-thickness thermal resistance of PCB materials specific to high-brightness LED applications.
- Test Conditions: Standardized environmental conditions-such as temperature, humidity, and atmospheric pressure-are specified to ensure test consistency and repeatability.
- Specimen Preparation: Guidance is offered on specimen pre-conditioning, die attach using metal paste, wire bonding, and sensor calibration.
- Testing Equipment: Recommendations include the use of specific thermal test chambers (as described in EIA/JEDEC STD 51-2), TEG (Test Equipment Group) chips to simulate LED heat sources, and methods for arrangement within test apparatus.
- Calculation Methods: The standard details how to obtain values for thermal resistance (both plane-wise and through thickness) and the transformation of these results into relevant parameters such as heat transfer coefficients and thermal conductivity.
- Quality Assurance: Emphasis is placed on minimizing measurement variability, controlling environmental factors, and ensuring accurate, repeatable results.
- Classification and Application: Annexes provide a framework for classifying PCBs by thermal properties and demonstrate mapping of thermal conductivity and heat transfer coefficient relevant to PCB base materials.
Applications
IEC TR 61189-3-914:2017 is highly relevant in the following contexts:
- High-Brightness LED Lighting: Ensures reliable thermal management for PCBs in LED luminaires, enhancing performance and service life.
- PCB Manufacturing: Supports quality control processes by delivering standardized test methods for evaluating heat dissipation capabilities.
- R&D and New Product Introduction: Assists engineers in selecting or developing PCB materials with optimal thermal characteristics for high-power electronic assemblies.
- Testing Laboratories: Provides a reference framework for conducting comparative thermal conductivity measurements, reducing uncertainty and variability between different organizations or operators.
- Supplier and Customer Agreements: Offers a classification system based on thermal performance, facilitating clear communication and specification compliance among stakeholders.
Related Standards
- IEC 61189-3-913: Main test method for measuring thermal conductivity of electronic circuit boards for high-brightness LEDs; IEC TR 61189-3-914 provides supplementary guidelines and precautions.
- IEC 60194: Covers terminology related to printed board design, manufacture, and assembly.
- IEC 60068-1:2013: Outlines general requirements and guidance for conducting environmental testing, ensuring standardized test atmospheres.
- EIA/JEDEC STD 51-2: Describes environmental conditions for integrated circuit thermal testing in natural convection (still air) environments.
Implementing IEC TR 61189-3-914:2017 enables organizations to accurately assess and classify the thermal performance of printed circuit boards in high-brightness LED applications, supporting product safety, reliability, and long-term performance in demanding electronic systems. Adherence to these guidelines also promotes consistency across global supply chains and enhances the comparability of test results within the electronics industry.