Abstracts by Session

Session F: Automotive Electronics
Wed 10:40 – 11:20 Andreas Aal From embedded safety dominated ECUs towards cyber secure high performance computing systems – an automotive industry’s review

The advantages of electronic dominated functions realized within road vehicles clearly did lead to more safety, comfort and improved environmental footprint.

However, with changing business models like mobility and transport as a service (MaaS, TaaS) as well as various associated autonomous driving concepts and capabilities (machine learning, swarm intelligence and remote guidance), vehicles themselves receive the new role of a mobile device amongst many within a digital telecommunication ecosystem.

Historically, the increase of functions was realized through scaling the number of ECUs as well as through an increase of their complexity both from a hardware as well as a software perspective. While ever increasing the number of distributed ECUs has a simple space availability limit associated with it, in addition and unfortunately, the increase of complexity of advances embedded system was less innovation, but rather closed automotive ecosystem driven.

This has two major consequences for the automotive transformation process. First, it limits the adaptability of state-of-the-art and proven innovations from non-automotive sectors. Second, established cyber security measures associated with those innovations are not or not 1:1 applicable. Third, distributed ECU architecture of paired with countless HW and SW variants of the same function, which are mostly proprietary implemented, result in a principle cyber security vulnerability that is very hard to countermeasure.

The assumption that cyber security is a software topic is a typical misconception. We will discuss the concept of cyber resilient systems and the importance of the combined view on hardware/software co-designed architectures.

Wed 11:20 – 11:40 Oliver Senftleben Reliability as a key Challenge for future Vehicle Architectures

Digitalisation, Electrification and Autonomous Driving demand for new E/E architectures in modern passenger vehicles.

New functional demands with respect to online connectivity, over the air updates and additional use cases like bidirectional charging, C2X communication or online health monitoring impose additional demand with respect to operating time, switching cycles and centralized multi-function integration platforms which are not only active during driving or charging mode but also have significant operation times during on- and off-grid parking.

Assessing and qualifying modern ECUs with respect to these requirements results in ultra-long qualification times which are violating the demand of shorter development cycles and tighter development plans.

New qualification strategies will therefore not only have to follow a robustness validation (RV) approach instead of conventional test-to-pass methodology but also have to utilize modern physics-of-failure approaches for proper life time assessment based on dedicated mission profiles.

Wed 11:40 – 12:00 Davina Nienhues Corrosion on Semiconductor Surfaces – Determination of Ionic Contamination Limits

For safety-relevant devices like airbag systems the prevention of failures is crucial. Therefore, the investigation of the detrimental factors like ionic contamination and environment is key to understand and prevent these kinds of failures. For microelectronics the requirements are much higher compared to large scaled systems like printed circuit board assemblies (PCBAs), since distances of 20 µm and smaller are common. The signals of sensible devices can be disturbed by a leakage current of 100 pA. Such an increase in leakage current, for example caused by chloride in combination with humidity, can be the initial step to electrical changes and corrosion besides shifted signals.

For small distances ionic contamination limits are missing. Therefore, this work discusses the increase in leakage current using exact DC current measurements up to a few picoampere. As well as the change in impedance and the formation of corrosion products, all three related to sodium chloride contamination. The test dies have aluminum copper (AlCu(0.5%)) interdigital structures on the surface with small distances (<20 um), are mounted on PTFE-based PCBs and were tested at high humidity and temperature.

Wed 12:00 – 12:20 Robert Klengel Comprehensive Study of Long-Term Reliability of Copper Bonding Wires at Harsh Automotive Conditions

Copper (Cu) has been by far the most widely used bonding wire material in the consumer electronics sector for several years now. However, gold (Au) bonding wires still dominate in many automotive applications. But even in this field, there have been efforts for years to benefit from the significant cost advantage of Cu compared to Au. There are various Cu wires in the market, which are now increasingly advancing into applications with challenging conditions and high reliability requirements. The present study investigates the suitability of Cu materials to meet the reliability aspects following the AEC-Q006 requirements. In a bonding wire evaluation, two palladium-coated Cu (APC) wires were considered – a conventional APC wire and the EX1R wire optimized for harsh application conditions. In the presentation, each test results will be summarized, but a more in-depth analysis will be given to the high-temperature storage life tests at 150°C and 175°C, where the most significant differences occurred. Overall, the results show the importance of material reliability knowledge upfront a device qualification process (robustness validation) and give further guidance for material selection.

Wed 12:20 – 12:40 Horst Theuss Packaging of MEMS and Sensors

“Advanced Packaging”, as typically defined by market researchers is mainly driven by edge computing. It requires high density low pitch interconnects for thin dice. Requirements for MEMS are different – the interconnect density is low, semiconductors reveal high thicknesses and specific materials are in use. Looking down the roadmap, further miniaturization and integration trends may lead to sensor systems requiring novel assembly concepts, which merge these two worlds. This presentation will review package requirements for MEMS. It will also highlight some specific challenges, which the MEMS-particularities impose on failure analytics.

Wed 12:40 – 13:00 Heiko Stegmann Characterization of power semiconductor junctions by combining three-dimensional FIB-SEM imaging and EBIC

IGBTs and SiC based MOSFETs have become the most frequently used power semiconductors for automotive applications. For failure analysis, it is essential to fully understand their construction and operation, in particular junction profiles. To this end, we combined EBIC measurements and 3D visualization of structure and dopant distributions by FIB-SEM tomography. EBIC at an oblique focused Ga-FIB cut made in the device top surface can easily and quickly image the p/n junctions. Secondary electron imaging in the SEM can highlight areas with different implant distributions in FIB prepared cross-sections. Extending SEM imaging into the third dimension can be achieved by FIB-SEM tomography, where thin layers are repeatedly removed from the sample using the FIB, and SEM images are recorded after each removal step. For process monitoring, such an image stack reveals deviations in the device structure and allows to determine the precise volumetric shape of implant regions. For an isolated electrical failure, such data complement EBIC junction health measurements by providing the exact shape of a dopant problem, as well as immediate 3D characterization of its neighborhood.