The National Institute of Standards and Technology (NIST) has identified critical measurement and standardization gaps in polymer-based semiconductor packaging with direct consequences for automotive sensor and electronic control unit (ECU) reliability. The finding has prompted the agency to advance new test materials, metrology protocols, and open data frameworks as the automotive supply chain watches closely.
Background
The NIST initiative stems from a perspective paper published in IEEE Transactions on Components, Packaging and Manufacturing Technology in 2025, building on an agency-organized workshop held at the 35th annual Electronics Packaging Symposium in Binghamton, New York, on September 5, 2024. The paper, co-authored by researchers from NIST, North Carolina State University, the National Renewable Energy Laboratory, Intel, ASE, and Binghamton University, outlines what its authors describe as systemic shortfalls in how polymer encapsulants are characterized, qualified, and modeled for advanced packaging applications.
The relevance to automotive electronics is acute. Polymer compounds - epoxies, silicones, and polyimides - are the dominant encapsulation materials for ECUs, ADAS sensors, and related modules. Plastic packaging now holds more than 99% of the total electronics packaging market share, having displaced hermetic ceramic and metal housings from a position of 80% market dominance in the 1960s. Yet, according to a 2025 study published in Frontiers in Electronics, mechanical vibrations in automotive environments cause stress cycling that leads to fatigue failures including delamination and cracking at the encapsulant-die interface, as well as solder fatigue from accumulated plastic strains at the board level.
Existing automotive electronics qualification frameworks - including AEC-Q100 for integrated circuits, AEC-Q101 for discrete components, AEC-Q200 for passive components, and ISO 16750-3, which specifies vibration test profiles across frequency ranges up to 2,000 Hz for vehicle-mounted electronics - address system-level performance thresholds. They do not, however, provide standardized protocols for characterizing fundamental polymer material properties such as cure kinetics, residual stress, moisture absorption dynamics, and viscoelastic behavior that underpin long-term package integrity.
Details
The NIST-led effort, operating under the agency's CHIPS metrology program, centers on two parallel workstreams. The first involves developing advanced metrology methods - including rheology, spectroscopy, and in-situ stress measurement techniques - to track how polymer encapsulants cure, shrink, and deform during manufacture. According to the NIST CHIPS team, these efforts aim to advance the fundamental understanding of structure-property-processing relationships and promote standardized guidelines for material characterization.
The second workstream focuses on creating Research-Grade Test Materials (RGTMs): open, nonproprietary polymer systems that function as benchmarks, allowing researchers across industry, academia, and government to compare results, improve reproducibility, and generate reliable data for computational models. Unlike commercially sourced "black box" encapsulants - whose formulations are proprietary and often opaque to downstream users - RGTMs are designed to yield results transferable across organizations and simulation platforms.
"Modeling without metrology is imagination," stated William Chen, Chair of the IEEE Heterogeneous Integration Roadmap for semiconductors, and a co-author of the NIST perspective. The comment underscores a tension familiar to automotive polymer engineers: digital twin models of ECU packaging behavior are only as reliable as the measured polymer data fed into them. As the industry shifts toward 3D heterogeneous integration, where multiple chips are stacked or linked in three dimensions, the performance demands on encapsulant polymers are rapidly escalating.
Compounding the challenge is the automotive operating environment itself. Combined vibration and thermal cycling tests, as described under IEC 60068-2, subject printed circuit board assemblies to vibration while cycling through temperature extremes of -40°C to 125°C, replicating engine compartment conditions. Under such regimes, polymer packaging materials absorb moisture and change shape under stress, behaviors that can cause chips to warp, signals to degrade, or connections to fail over years of operation.
Outlook
The NIST framework does not yet carry regulatory weight within automotive qualification pathways such as IATF 16949 or the AEC-Q series, and the agency has not announced a dedicated automotive-sector test suite. However, the push to establish shared RGTMs and open polymer property databases is expected to inform future revisions of both AEC qualification standards and OEM-specific material approval processes.
Industry participants will monitor whether NIST's metrology outputs - particularly residual stress measurement protocols and cure kinetics databases - gain adoption by standards bodies such as JEDEC, IEC, or SAE International as reference inputs for next-generation automotive electronics reliability specifications.
