To ensure that the myriad electronic systems in today’s vehicles do not fail prematurely, the AEC-Q100 standard for active components defines stringent tests across all aspects of performance.
This part continues the exploration of AEC-Q100 and its implications. Start with Part I, here.
Q: What’s the objective of AEC-Q100?
A: It’s simple: to establish standards for active devices to ensure that they have no failures in use.
Q: What’s the structure that makes this happen?
A: AEC-Q100 is a top-level standard that then “breaks out” in many specific, well-defined, committed sub-standards:
- Q100-001: Wire Bond Shear Test
- Q100-002: Human Body Model Electrostatic Discharge Test
- Q100-004: IC Latch-Up Test
- Q100-005: Non-Volatile Memory Program/Erase Endurance, Data Retention, and Operational Life Test
- Q100-007: Fault Simulation and Test Grading
- Q100-008: Early Life Failure Rate
- Q100-009: Electrical Distribution Assessment
- Q100-010: Solder Ball Shear Test
- Q100-011: Charged Device Model (CDM) Electrostatic Discharge Test (New)
- Q100-012: Short Circuit Reliability Characterization of Smart Power Devices for 12V Systems
(Note that Q100-003 and Q100-006 are omitted as newer standards have superseded them.)
Q: A complete electronic system consists of more than active components. How does AEC-Q100 address that?
A: It doesn’t. It’s only for active electronic components (discrete devices and ICs). Complementary standard AEC-Q200 is for passive components. There are also standards for multi-chip modules.
Q: Does the standard cover the design and manufacturing of the circuitry, circuit boards, and assemblies that use these certified components?
A: No. It is tightly focused on the reliability of components as individual items. Even “perfect” components can be part of marginal designs, have EMI/RFI issues (both due to sensitivity or as source), or have quality issues with manufacturing, but the AEC-Q100 does not cover those; the intention of the standard is to ensure that the active devices which are the basic building blocks of the circuits and systems are extremely reliable under the automotive conditions, then build up from that foundation.
Q: What other defining standards are there for automotive designs?
A: Automotive design has a large ecosystem that is covered by numerous standards from many perspectives, covering safety, reliability, performance, and more (Figure 1).
Figure 1. The automotive-standard environment is a complex one; AEC-Q100 is just one of many critical documents (Image: Monolithic Power Systems).
Q: It seems impractical to strive to zero failures; why not just accept failures, but at a low level?
A: First, there’s a tangible impact on the car driver, particularly if it occurs at a critical time (have to get to a doctor’s appointment) or a safety-related function fails (steering or turn signals). Safety-related failure could lead to personal/family misery, stress, and costly lawsuits. There’s also the psychological effect of failures or malfunctions in non-critical functions such as infotainment, which would be not only annoying but also detrimental to the brand’s reputation.
Q: Aren’t there sophisticated alternatives, such as redundant designs or advanced circuit and system topologies?
A: Redundant design is used but only sparingly in extremely critical aspects of the car. It is not a panacea. It’s costly and requires more space and more power. Also, a redundant design is a complicated design: do you have a primary circuit and a backup, or have both in parallel and some oversight scheme? How do you determine that the primary one is out-of-spec or failed? What does the switching scheme look like?
Adding more components, even if for redundancy, adds more points of potential failure and brings a new set of issues and problems. Also, it’s not practical to have redundancy for less-critical functions, yet you don’t want to frustrate the car owner when the radio fails. A better approach is to design parts with extensive built-in self-test in-depth error reporting, including under-range, over-range, and benign failure modes.
Q: Is there a single grade when a part is AEC-Q100 qualified?
A: No, there are grades within AEC-Q100, mostly related to temperature. A part going in the trunk is not stressed as highly as one near the engine with respect to temperature and other factors such as vibration). AEC-Q100 defines four temperature grades, and a part will be designated as AEC-Q100 Grade X to signify which one, where X is 0, 1, 2, or 3:
- Grade 0: -40° to 150°C
- Grade 1: -40° to 125°C
- Grade 2: -40° to 105°C
- Grade 3: -40° to 85°C
Q: Is there a top-level summary of the differences between a part for consumer use versus one for automotive use, which is AEC-Q100 qualified?
A: While there are many differences, Figure 2 shows a high-level perspective. Note the automotive entry for “Acceptable Failure Rates” — that’s a stringent, unambiguous requirement.
Figure 2. There are orders of magnate differences between basic expectations for a non-consumer product and a car.
Q: How do the tests for AEC-Q100 qualification relate to the standard reliability and failure “bathtub curve”?
A: The tests are intended to weed out “infant mortality failures” and “end-of-life” failures (Figure 3).
Figure 3. Reliability is usually characterized by early-life initial failures and an end-of-life wear-out phase via the well-known “bathtub” curve (Image: Texas Instruments).
Early Life Failure (ELF) testing is performed to screen out units that would fail prematurely if they were used in normal operation. At the other end of the timeline, High-Temperature Operating Life (HTOL) tests are the opposite of ELF, stressing the reliability of the samples in their wear-out phase.
The objective of AEC-Q100 is to drive early life and useful life failures to zero and ensure that wear-out failures don’t occur for 10 to 15 years.
Q: How are the tests implemented?
A: While the setup and arrangement differ for the specific phases of the overall process, Figure 4 shows one typical test scenario. In short, it’s quite stringent.
Figure 4. The tests used for AEC-Q100 qualification involve many samples, lots, test regimes, and an extremely difficult standard of perfection (Image: Monolithic Power Systems).
Q: Is that all?
A: Not at all. There are also tests and inspections at the wafer level and die level before the final discrete or IC packaging. Again, it’s a complex process covering the entire cycle from basic fab to the finished part.
Q: Is there a price premium for these parts?
A: Yes and no. On one hand, the qualification process is costly. On the other hand, the associated volumes are high, so that the cost can be amortized. It depends on the specific part.
Q: Does anyone else benefit from the AEC-Q100 designation?
A: Yes, since most discrete device and IC vendors offer these parts as standard catalog items, non-automotive users can buy them for their harsh environment applications.
Q: Are AEC-Q100 parts qualified for space use?
A: It might be a start, but many other standards exist for space-qualified parts. Those specific standards depend on the “where“ of the space application (low Earth orbit, geosynchronous orbit, deeper-space mission) and the “what” including planned mission longevity. Each of these has different requirements for operation in a vacuum: outgassing, radiation tolerance, thermal performance, and vibration resistance. An AEC-Q100 part might be suitable for automobiles but will not meet all the additional criteria for space-qualified use.
Conclusion
The development of AEC-Q100 and the associated family of reliability standards for active components has transformed how designers think about reliability and failure, moving it from acceptable at some pre-specified level to unacceptable. It has enabled engineers to add electronic features and functions to cars, ranging from those for comfort and convenience to those affecting critical safety roles.
The stringent demands of AEC-Q100 have shown what was impractical or impossible to show that extreme reliability is, in fact, doable.
EE World related content
- 4D imaging radar on-a-chip is automotive-grade, AEC-Q100 qualified
- AEC-Q-100-qualified flyback switcher boasts 30 V to 550V DC input efficiency
- Clock generators, buffers, and PCIe clocks/buffers AEC-Q100-qualified for auto apps
- Gate-driver IC family certified to AEC-Q100 Grade Level 1 offer high-power safety and functionality
External references
- Monolithic Power Systems, “Fundamentals of AEC-Q100: What ‘Automotive Qualified’ Really Means” (very useful and informative)
- Qorvo, Inc. “Automotive Quality Standards 101: What Qualification Really Gets You”AEC Council, “AEC Documents” (useful and informative)
- Japanese Motor Works, “The Average Car Has 30,000 Parts. Which Are Most Important?”
- Texas Instruments, “TI Application Report SNOA994: Calculating Useful Lifetimes of Temperature Sensors” (not about AEC-Q100, but a good overview of reliability and lifetime)
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