Issued Date: 2019/4/24
Assistance Systems (ADAS) that were just a concept a few years ago are now a reality. Some mid-tier vehicles entering the market in 2018 came with ADAS and more are expected in 2019. According to the Automotive Research & Testing Center (ARTC), the cost of semiconductor components per car has exceeded US$330 and in electric vehicles, the amount comes close to US$1,000. The automotive electronics market is completely different from the consumer electronics market that Taiwan-based IC makers are familiar with.
Allan Tseng, iST’s assistant vice president notes that automotive systems have always imposed stringent requirements on reliability and are beginning to demand high performance as well in recent years. Vendors looking to expand into automotive electronics are advised to pay attention to both product reliability and performance.
Reliability has constantly been a top concern for automotive electronics. On top of this, with IoV and AI technologies being growingly incorporated in automotive IC, performance is also becoming an important consideration, which is bringing changes to IC design. According to Tseng, semiconductor chips have been housed in BGA, QFP and SOP packages, which are mature packaging technologies but have difficulty meeting the demand ofnew-generation IoV communication standards such as AI, HPC,C-V2X(Cellular V2X) and DSRC(Dedicated Short Range Communication) for transmission speed. This gives rise to advanced packaging technologies including Multi-Chip Module (MCM), System in Package (SiP) and Fan-in/Fan-out, which can expect to become the prevailing trend but will also have to stand the test of quality, safety and reliability.
The automotive industry has established comprehensive standards on quality and safety. IATF 16949 sets the requirements for an Automotive Quality Management System (QMS). Compliance to VDA 6.3 is mandated by some European automakers. For the mass production phase, new IECQ Automotive Qualification Program (AQP) gives the automotive industry a standardized way of testing components to ensure quality. ISO 26262 specifies functional safety of electrical and/or electronic systems in production automobiles. As to reliability, it has to be evaluated respectively on the device, board and module levels, each of which represents a step in the IC packaging process. If a semiconductor chip can pass reliability tests for all three levels, it can be used in an automobile.
Three major challenges for automotive components
Automotive Electronics Council (AEC) has defined common electrical component qualification requirements in automotive applications. AEC-Q100 specifies failure mechanism based stress test qualification for integrated circuits, AEC-Q101 for discrete semiconductors, AEC-Q102 for discrete optoelectronic semiconductors and AEC-Q200 for passive components. Automotive components to qualify for these standards must pass heat dissipation, material warpage and sequential stress tests.
In the harsh automotive environment, heat has always been the biggest challenge in component reliability. Today’s automotive systems demand high-performance components that inevitably have high current consumption, which brings even more challenges to component reliability. As such, developers strive to strike a perfect balance between performance and power consumption. Another common and serious problem with automotive components is IC package warpage. To keep up with the demand for high-speed data transmission, automotive semiconductor chips are growingly packaged in MCM/SiP assembly, instead of BGA. However, an MCM package combines a mix of multiple chips, active and passive components and PCB with different thermal expansion coefficients (CTE)integrated in a module so it is susceptible to warpage and deformation in an automotive environment with drastic temperature changes. Such a problem plagues not only IC devices but also print circuit boards (PCB). According to Chia-Hao Chuang, manager, board level reliability engineering, iST, high frequency is now a common design in automotive systems and will become a fundamental design in the 5G era. High frequency systems require PCB made with a special material of which the thermal expansion coefficient at a high temperature may be four times higher than at room temperature, resulting in severe package warpage.
Last but not least, more challenges arise from new AEC-Q104, highlighting sequential stress tests, which AEC has been applying to modules for years and has extended to components beginning 2018. AEC established AEC-Q104 in consideration of the fact that automotive systems in real-world use scenarios are subject to a series of conditions and therefore automotive systems and their components must be able to cope with a set of qualification stress test sequences.
In the past, chips were packaged individually with simple material composition and assembly structure so they could be tested one by one. Today, advanced packaging , such as MCM and SiP, integrates different types of chips with varying characteristics, which may fail in an automotive environment when a series of conditions happen. AEC-Q104 specifies that chips must pass each step in a sequence of stress tests. For example, high-temperature operating life (HTOL) and thermal shock tests used to be conducted separately. AEC-Q104 requires that chips undergo an HTOL test followed by a thermal shock test and they must pass both to be considered compliant. This not only makes testing more time-consuming but also incredibly challenging. Although AEC-Q104 compliance is not mandatory at present, most automakers do require their components to meet AEC-Q104 standards, notes Tseng. Accordingly, it is important for suppliers looking to expand into the automotive sector to obtain AEC-Q104 certifications for their products.
Challenges for automotive PCBs
Suppliers often need to address another problem with automotive PCBs. That is, the PCB they have designed according to the specifications may be quite different from what is actually needed in real application. The traditional approach is to come up with an initial PCB design based on the specifications and then make adjustments on the fly until a usable version is available, which consumes tremendous time and effort.
iST crafts a complete testing platform combining software and hardware
To solve problems with IC devices and PCBs in automotive systems, iST makes use of new tools, both software and hardware. It has built a platform that can measure the warpage of IC packages and PCBs before the surface mount process to help customers ensure soldering quality.
iST works with US-based DFR Solutions (DFR) to design PCB simulation software. DFR is a renowned consulting firm in the automotive sector. Its Sherlock Automated Design Analysis software has been adopted by leading American and European automakers. iST makes use of the massive data accumulated by Sherlock in the past and is able to find stress parameters in all kinds of applications such that PCB design can closely match real use conditions. Sherlock serves as a tool to analyze materials’ thermal expansion coefficients, malleability and response to external stress prior to reliability tests. It can also work with widely-used computer-aided engineering (CAE) tools to significantly reduce the time it takes to conduct analyses.
ADAS are enjoying a rapid rise in popularity beginning in 2018, spurring new opportunities for the semiconductor industry. Technology firms in Taiwan are gearing up toward automotive electronics development. As automotive systems are quite different from consumer electronics in terms of design thinking, industry ecosystem, requirement standards and particularly test procedures, Tseng advises that Taiwan firms leverage third-party help in their endeavors toward the automotive market. iST has many years of experience in automotive electronics testing and can guide Taiwan firms in the right R&D direction, shorten time-to-market and help them build up competitive edge.
Allan Tseng, assistant vice president, iST (right) and Chia-Hao Chuang, manager, board level reliability engineering, iST, both advise that Taiwan-based firms looking to expand into the automotive market should leave their old consumer electronics thinking behind.
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