Automotive Technology


An overview of the Automotive Electronics Council AEC-Q standards


By Jesper Rasmussen, director of electronic components, Conrad Electronic


M Automotive safety and reliability


any of us will remember the days when a heavy toolbox full of wrenches was a standard car


accessory. Not so anymore; the complexity of mechanics and electronics ‘under the hood’ means a logic and communications protocol analyser might be more useful. The scale of processing power in a typical car today is amazing – upwards of 100 processors running 150 million lines of code, more than ten times the number in a Boeing 787 Dreamliner. All this interconnected by high speed communication buses using multiple protocols.


Reliability is a major issue, because of the sheer number of components utilised and also because of the environment; wide temperature excursions are routine from cold start in the arctic to engine compartment extremes in desert climates. Shock, vibration and humidity also add to the stress. Perhaps the worst condition for electronics is thermal shock, testing the effect of differential thermal expansion rates to the extreme. In the 1970s, electronics crept into vehicles for ignition timing and automatic gear shifting. In the 1980s, engine Electronic Management Systems (EMS) became common and safety became an issue. Ironically, in the 1990s the automotive manufacturing industry felt that they were not getting sufficient attention from component suppliers due to their relatively small demand and that to ensure quality, some standards needed to be imposed specific to the industry.


The Automotive Electronics Council This is where AEC, the Automotive Electronics Council came in. Founded by Chrysler, Ford Motors and Delco Electronics, they established a common series of standards, AEC-Q100, AEC-Q101 and AEC-Q200, for the stress testing and qualification of electronic components intended for specific application areas in automotive. Originally, AEC had an interest in quality systems through their Quality Systems Committee but this became inactive and the function was covered by manufacturer QA systems approval to ISO/TS 16949, generated by the International Automotive Task Force and the International Standards Organisation. This in turn was superseded by the


process-orientated IATF 16949:2016 standard which is based on enhancements to the general industry quality standard ISO 9001:2015. Amongst many changes, the IATF standard emphasises recent issues in automotive such as requirements for safety-related parts and processes, embedded software reliability and corporate responsibility. As a word of caution, there are components advertised as AEC ‘compliant’ rather than ‘certified’. These parts may meet the intent and requirements of the AEC specifications but are typically from suppliers who do not hold TS/IATF 16949 certification because they do not control the complete manufacturing process.


The AEC-Q standards It should be appreciated that the AEC-Q standards are not ones used by test agencies to qualify components, they are used by suppliers to ‘self-certify’ to show compliance. The standards are also a ‘base level’; individual automotive customers at any tier may impose further component qualification requirements for their particular application. While there are many tests specific to automotive, the AEC-Q standards also refer to documents from other sources such as MIL-STD-883, JEDEC, JESD, IPC and UL. Currently the standards are for components only, most modules or complete systems are not included and would need an agreed qualification specification between supplier and customer. Small encapsulated DC-DC converters are an example, although they can be extremely simple and regarded as a commodity component, they do not strictly fall into any AEC-Q qualification standard category.


The five main AEC-Q standard categories are AEC-Q100 – integrated circuits, AEC-Q101, - discrete semiconductors, AEC-Q102 for optoelectronics, AEC-Q104 for multi-chip modules and AEC-Q200 – passive devices. There are some common features to each standard: components are categorised into temperature grades for example. Table 1 shows the grades for integrated circuits. The standards are generally for methods


of stress testing and analysis rather than functional performance. Stress is not just environmental; electrical and mechanical tests are included along with the requirement to at least consider EMC


Table 2. Product Part Approval Process (PPAP) levels


effects. Failure modes considered are not simply short, open or parametric, evaluation of soft error rates (SER) in SRAM and DRAM due to radiation events for example, may also be part of qualification. AEC are pragmatic about the level of testing that is possible and in the case of soft error rates for example, would allow for built-in mitigation features such as error correction and Soft Error Detection (SED). Generally, there is positive encouragement to use generic data for component families that has been accumulated from internal testing and other customer qualification processes. The definition of a ‘family’ and lot and sample size, is carefully stated so that the maximum value can be obtained from data without undue risk. There is strong emphasis in the AEC-Q


standards on the ability of a supplier to maintain the stress tolerance of components in their real manufacturing process. Although the stress tests need only be done once, they must be performed on parts which have been fabricated using production tooling,


with specific tests including wire bond and solder ball shearing to ESD and short circuit performance of smart power devices. AEC-Q101 base standard and sub- documents 001 to 006 deal with testing of discrete semiconductors with a similar range of content, again including ESD and wire bond shear testing.


AEC-Q102 is exclusively for opto-


electronic devices. High temperature operation of these devices is a particular emphasis in tests due to the inherent limitation of opto-electronics in this respect. The common environmental, mechanical and ESD tests also apply. A new standard released in September 2017, AEC-Q104, covers ‘multi-chip’ modules with active and passive components combined into a single package for reflow solder attachment to a printed circuit board. Power modules are still deemed to be outside the scope of the standard, typically requiring specific, agreed, extra test procedures


AEC-Q200 and sub-documents 001 to 007 for passive components covers a wide


Table 3. AEC-Q temperature grades for passive components


processes and operatives, using non- consecutive lots. If anything in the component or manufacturing process changes, requalification is necessary using the Product Part Approval Process (PPAP). Created by the Automotive Industry Action Group, the PPAP has its own levels of applicability ranging from 1 to 5 with increasing requirements for sample submission and supporting data. Table 2.


Table 1. IC Component temperature grades according to AEC-Q standards 26 February 2019 Components in Electronics


AEC-Q100 base standard covers stress test qualification of integrated circuits and gives the general principles. Sub documents AEC-Q100-001 to 012 deal


range of parts and their tests. Again, the application is graded according to temperature (Table 3). Note that grade’0’ parts are specified to +150°C, 10 degrees higher than for integrated circuits. Documents AEC-Q001 to 006 are a collection of guidelines covering test analysis and some specific requirements for ‘lead free’ evaluation, copper wire bond interconnects and perhaps the subject that sums up the intent of AEC-Q standards – the goal of zero defects during a product’s lifetime and assured safety.


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