Demistifying Derating
Abstract
Kirk and Fred discussing the reasons and practice of derating components for the purpose of improving the reliability of electronics products, as Kirk’s experience has shown most causes of unreliability are due to mistakes and overlooked errors in design, use, or manufacturing
Key Points
Join Kirk and Fred as they discuss the need and benefits or lack of benefit in the classic methods of derating components for the purpose of improving reliability.
Topics include:
- Most electronics made have more intrinsic fatigue life than will ever be needed as technological obsolescence typically comes long before electronic components wear out. Even most mechanical parts as in buttons, relays, have extensive use life.
- It is agreed that creating larger operational margins in electronics improves reliability, but using blanket derating guidelines may add cost versus finding the one component through HALT of the system and increasing the strength of component.
- Finding the root cause of a component failure is important, but sometimes you just increase the limiting component and applying HALT to verify increase in stress-strength margins.
- If you cannot trust the component manufacturers ratings, why would you use that component.
- Component manufacturers all have margins in the component specifications to allow for variation in manufacturing, but there is no standard and most never will disclose the actual margins that the component design has.
Enjoy an episode of Speaking of Reliability. Where you can join friends as they discuss reliability topics. Join us as we discuss topics ranging from design for reliability techniques to field data analysis approaches.
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Show Notes
Here is a link to Kirk’s article “There is a drain in the Bathtub Curve” , still relevant 8 years after it was first published
Click on this link to access the article “Reliability Prediction – A Continued Reliance on a Misleading Approach”
For more information on the newest discovery testing methodology here is a link to the book “Next Generation HALT and HASS: Robust design of Electronics and Systems” written by Kirk Gray and John Paschkewitz.
Like the discussion about derating. I have referred to derating as “poor mans DfR” but it is also sometimes very costly from a BOM perspective. With all new tools derating has been put aside as product optimization from cost and size perspectives are the highest priority. Based on feedback from std component suppliers it seems to me that derating now again gain some interest mainly because all possible ways to keep the failure rate low have to used to reach product return rate goals on complex products.
Derating is definetly no silver bullet and not HAST either but both are necessary tools to keep the failure rate low.
Thanks for the comment Bo.
I do not believe there is any silver bullet in the quest to insure reliable products, but some tools are certainly more useful than others in finding unreliability.