By Dan Friedlander
Retired following 44 years in component engineering
There are no step-by-step instructions for achieving zero defects, and there is no magic combination of elements that will result in them. There are, however, some guidelines and techniques to use when you decide you are ready to embrace the zero defects concept. The above-mentioned"AEC-Q004 Zero Defects Guideline" is indeed addressing the issue as guidelines.
The term "zero defects" may have different interpretations, as seen below:
AEC-Q004 in para. 6.4 "Environmental Stress Testing" defines the addressed defects before the component delivery to customer:
Para. 6.4.6 "Defect type addressed (ongoing or spike)"
"For design, defects include unusual temperature dependencies, performance irregularities and marginalities, and functional problems. For process, defects include time/temperature defects, unanticipated infant mortality issues, latent defects, and wearout mechanisms. For packaging, defects include structural integrity, unusual package related anomalies (delamination, popcorn) and sensitivities, and assembly related defects that affect quality and reliability. Gross issues are detectable."
Take another EEE component manufacturer: Altera (now part of Intel). Presenting Altera’s Automotive Quality Program, it is stated that "Quality in Everything We Do to Ensure the Customer’s Total Experience," meaning "Deliver defect-free products and services on time."
The "Zero-defect strategy" is presented: "The core of Altera’s ongoing continuous improvement process is its Zero-defect strategy. Altera and its manufacturing partners work closely together to drive down defects by continually implementing manufacturing process improvements and enhancements. Altera’s current customer return defect rate for automotive products is under 1 dpm (defect per million) and our corporate level zero defect roadmap will take us to even lower defect rates."
Hopefully, the relevant "zero defect" goal is referenced to the "Deliver defect-free products" and not to the "customer return defect rate." The latter belongs to a different issue. In the same "zero-defect strategy" it is stated: "The following factors play a key role in the success of our comprehensive Zero-defect program." As mentioned above, the "zero defect" is not a program.
To correctly assess the "superiority" of the automotive grade EEE components versus industrial EEE components, following are the main elements in the relevant methodology to be considered and not limited to:
- AEC-Q100 is dealing with qualification requirements only.
- A one-time qualification is required for a new device family. No periodic qualification verification is required.
- The use of generic data to "simplify" the qualification process is strongly encouraged.
Para. 3.1 of AEC-Q100 Qualification of a New Device:
"For each qualification, the supplier must have data available for all these tests, whether it is stress test results on the device to be qualified or acceptable generic data."
- Requalification of a device is required when the supplier makes a change to the product and/or process that impacts (or could potentially impact) the form, fit, function, quality and/or reliability of the device.
- There is no qualifying activity to certify whether the EEE component manufacturer meets the requirements of AEC-Q100.
- The EEE component manufacturer has the authority to self-approve his products as "AEC-Q100 qualified".
- Each User is responsible to review the qualification data to verify compliance to AEC-Q100.
- Screening is not required.
Nevertheless, it is interesting to find in para. 4.1,Figure 2: Qualification Test Flow, that the qualification is done on components that passed through an undefined step, named "Defect Screening (e.g., burn in)"! No further reference found.
Automotive grade vs. industrial grade
The above highlighted elements of the AEC-Q100, points to a professional document containing a baseline of minimum requirements for qualification. Successful test results after performing all the specified one-time qualification addresses robustness. However, the reliability is not addressed.
An AEC presentation states in context with disadvantages of the stress test qualification methodology (applicable to AEC-Q100): "cannot measure reliability, only can say the test passed (robustness)."
The AEC-Q100 contains a set of tests well known in the semiconductor domain. Consequently, most of these tests (if not all), at applicable test conditions, are applied also for any standard COTS.
The most outstanding automotive tailored parameter is the extended operating temperature range. One of the main issues addressed in the AEC-Q100 is the tests adaptation to the relevant automotive operating temperature grade.
The narrower industrial operating temperature range -40°C - +85°C is in general enough for a space application (always there are exceptions).
The intimate interaction between the EEE component manufacturer and the automotive user, as mentioned in the AEC-Q100 is wishful thinking for a space user.
There is no argument that the controlled qualification baseline documentation in writing has his own value. Nevertheless, it would be worth to know and better understand the difference between an industrial-grade EEE component and an automotive-grade EEE component in terms of quality and reliability and not in terms of operating temperature range. Not having the prerogative of an automotive user (at least as stated in AEC-Q100) to access component manufacturers' relevant not published information, it is rather difficult (in diplomatic wording) to find explicit production flows for both grades.
A lot of argumentation is available to claim better quality and reliability for automotive EEE Components. The term "AEC-Q100 qualified" is the strongest, most impressive argument. If a "simple" user tries to assess what is done beyond the above one time qualification requirements, he will have to resort to general routine wording/slogans. If one wants to find out what are those advertised “special measures,” “extended measures,” “best commercial practice,” etc., he will probably end up frustrated (like me).
Just to exemplify the situation, take Texas Instruments (TI), a reputable EEE component manufacturer offering automotive grade. TI also offer Enhanced Plastic (EP) grade, considered by them superior. For example, the scenario for trying to find the applicable flow in order to compare grades goes like this:
Question (from TI Enhanced Plastic Portfolio Q & A): "What is the process and test flow?"
TI answer: "Testing and screening of EP products is performed in accordance with the TI data sheet for that device. Configuration control is performed by Texas Instruments. TI processes EP products per "best commercial practices" to the TI internal baseline flow. Processing and screening is documented in the TI Quality System Manual and is in compliance with ISO9001."
You will not find any flows in the datasheet or in the QSM 000 Rev. H Texas Instruments Quality System Manual. You will find general standard statements.
Here is another TI answer taken from "TIEnhanced Plastic Portfolio Q & A".
Question: "Why can't I just buy TI automotive grade parts and get the same thing?"
TI: "Catalog automotive products are just one form of off-the-shelf devices. To ensure change notification and extended baseline support, automotive OEMs procure to specific customer specifications."
It is worth to pay attention to what the above means:
- "AEC-Q100 qualified" catalog EEE components COTS meet the qualification requirements, but it may be that the automotive users are not purchasing them as is.
- Many large volume automotive electronic system manufacturers DO NOT buy “catalog” automotive grade EEE components. Instead, they procure via internal SCDs based on “AEC-Q qualified” catalog items.
When comparing datasheet of an automotive component versions vs. the industrial version, the operating temperature range is the main difference. However, the electrical parameters (test conditions, limits) may differ as well.
For a space user, assuming that the operating temperature range is not critical, the automotive version may be better (e.g., specified for extreme temperatures vs. specified for room temperature only) or worse (e.g., relaxed limits, worse test conditions). Anyway, as always, the right specification shall be used.
It is worth mentioning that a car bus voltage is only 12V vs. a much higher bus voltage of a satellite.
In most of the cases both automotive and industrial versions of the same component are offered. It does not make sense for the EEE component manufacturer to design and manufacture two different die versions. In other words, the automotive version is an uprated version of the industrial version or the industrial version is a downrated version of the automotive version. In most cases (if not all), both versions have identical dies manufactured on the same production lines. The built-in reliability, in such a case, is the same for the both versions.
One can argue about the robustness obtained through meeting the onetime AEC-Q100 requirements. However, in case of uprating/downrating the compliance to AEC-Q100 should apply also to the industrial-grade counterpart. Of course, the electrical testing test conditions (some manufacturers are calling it "screening") of each version should be different due to different applicable temperature extremes.
Read more of Dan Friedlander's articles: Click here to visit his page.
Author biography
Read more of Dan Friedlander's articles: Click here to visit his page.
Read more of Dan Friedlander's articles: Click here to visit his page.
Author biographyRead more of Dan Friedlander's articles: Click here to visit his page.
Read more of Dan Friedlander's articles: Click here to visit his page.
Author biography
