The National Institute of Standards and Technology (NIST) has released a formal perspective on measurement standards and material-qualification criteria for polymer-based semiconductor packaging, with direct implications for automotive sensor and electronic control unit (ECU) suppliers facing tightening reliability requirements.
Published in IEEE Transactions on Components, Packaging and Manufacturing Technology in 2025, the perspective-authored by the NIST CHIPS team in collaboration with researchers from Advanced Semiconductor Engineering, North Carolina State University, and the National Renewable Energy Laboratory-outlines critical challenges and opportunities related to polymer-based "soft" materials in advanced semiconductor packaging, with emphasis on polymer science, measurement science, and the strategic development of Research-Grade Test Materials (RGTMs).
Background
Polymers such as epoxies, silicones, and polyimides form the structural and protective backbone of automotive semiconductor packages, encapsulating chips, connecting them to circuit boards, and maintaining electrical integrity across a vehicle's operating lifetime. In ECU and sensor applications, these materials must survive demanding environmental profiles: automotive components are subjected to thermal cycling between -40°C and 125°C, vibration testing at frequencies up to 200 Hz, and humidity exposure to test for corrosion resistance, according to established qualification protocols including ISO 16750 and AEC-Q100.
The reliability stakes are high. A single failure in an ECU can lead to catastrophic consequences, including accidents or costly recalls, and automotive-grade components must endure operating temperatures from -40°C to 150°C and constant vibration, mechanical shock, and humidity for a lifespan that often exceeds 15 years.
Despite these demands, the polymer materials underpinning ECU and sensor packaging have remained largely unchanged. NIST noted that traditional materials, many of which have not changed much in decades, now face new performance demands driven by vehicle electrification, advanced driver-assistance system (ADAS) proliferation, and the shift toward 3D heterogeneous chip integration.
A core failure mechanism in sensor packaging is coefficient of thermal expansion (CTE) mismatch. When silicon die, substrate, and polymer molding compound are bonded together and subjected to thermal cycling, they pull against each other, creating significant mechanical stress at the interfaces. This stress can lead to die cracking, solder joint fatigue, or delamination-all of which affect field reliability and warranty exposure.
Details
The NIST perspective grew out of a workshop titled "Materials and Metrology Needs for Advanced Semiconductor Packaging Strategies," held at the 35th annual Electronics Packaging Symposium in Binghamton, New York, on September 5, 2024. It establishes a structured framework for addressing measurement gaps that have hampered supplier qualification and cross-industry data sharing.
Central to the framework is the introduction of Research-Grade Test Materials (RGTMs): open, nonproprietary polymer systems that serve as benchmarks, allowing researchers across industry, academia, and government to compare results, improve reproducibility, and feed reliable data into computer models. Unlike proprietary "black box" formulations, RGTMs are designed to be transparent and verifiable-a distinction of practical significance for automotive tier suppliers required to demonstrate material traceability under standards such as IATF 16949.
NIST is developing new measurement techniques including advanced rheology and spectroscopy to stress measurements, tools that track how polymers cure, shrink, and deform during manufacturing - factors that directly impact device reliability. The framework also calls for shared databases of material properties and advances in measurement standards, priorities identified by cross-sector workshop participants from industry, universities, and government laboratories.
William Chen, chair of the IEEE Heterogeneous Integration Roadmap for semiconductors and a co-author of the perspective, stated: "Modeling without metrology is imagination"-a formulation reflecting the framework's emphasis on measurement-validated simulation as a prerequisite for reliable material qualification.
Christopher Soles, NIST materials scientist and co-project leader, described the rationale for open test materials: "By providing shared, transparent materials, we can accelerate innovation across the entire ecosystem".
The framework's intended outputs include quantitative measurement methods, open-source materials data, model calibration frameworks, and predictive modeling tools to inform engineering design of advanced packaging systems. NIST stated these outputs will be shared with the semiconductor industry to drive polymer and package design improvements.
Outlook
With some new packaging materials taking 10 to 25 years to reach production, the authors stress that early, collaborative work is essential. This timeline underscores a long-horizon risk for automotive procurement teams that rely on packaging polymer suppliers with limited qualification transparency. As OEMs continue to expand ECU and sensor content per vehicle-particularly in battery electric and software-defined platforms-the NIST framework is likely to inform next-revision supplier approval processes and materials characterization requirements within existing standards bodies, including SAE International and ISO Technical Committee 22.
