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Design For Reliability: What Does DfR Really Mean?
March 20, 2008 |Estimated reading time: 2 minutes
Design for reliability. DfR. There is certainly no shortage of catchy abbreviations these days. After all, DfR follows on the heels of DfM (design for manufacturability), DfT (design for testability), DfE (design for the environment), and DfS (design for sourcing), and the over-arching theme of DfX (design for excellence).
But DfR has increasingly captured the imagination of the electronics industry, from ODMs to CMs, from OEMs to end-users.
The interest in DfR is understandable. Reliability assessment and assurance early in the design phase can reduce development time (by as much as 66%) and introduce amazing leverage into eventual product cost and performance. In addition, with technology improvements in electronics beginning to slow down (is your MS Word more powerful now than five years ago?) and cost reductions becoming less likely (who isn't in China?), reliability/availability is becoming a critical market differentiator and an indicator of gross margins.
As a major OEM in enterprise architecture explained: "Margins are so tight in this business that reliability plays a major role in our financial performance. If a unit requires more than one service call during its lifetime, our profit margin has been effectively eliminated."
As with most popular trends, the overwhelming interest in DfR has sprouted a number of activities, including books, courses, software, and consultants. Unfortunately, many of these training tools and experts are either provide too broad a focus (DfR is everywhere!), spend too much time on techniques (FMEA and FTA) instead of answers, or incorporate elements that are not truly DfR (MTBF, HALT, ALT, screening and failure analysis).
True DfR activity should be initiated before production, before prototype, before bread-boarding - am I dating myself with that last one? A virtual design, so to speak. At this stage, the critical DfR issues within electronics are part selection, component stresses, part placement and orientation, PCB layout, design for manufacturability (yes, Virginia, DfM is a part of DfR), and physics of failure (PoF).
Within each stage, a valuable instruction on DfR provides answers and insight. These can include the following:
* What are some of the new component selection criteria regarding Pb-free?
* Why are high-resistance resistors not always appropriate?
* How can we prevent flex cracking in the design stage?
* When is it time to move from plated through-hole to microvia?
* Which next-generation technologies are causing failures now, and how can we capture this in design?
Applying appropriate resources in the design process in combination with the right tools and knowledge can result in impressive reductions in design cycles and very effective mitigation in any risks that might affect your customer.
Because without reliability, what do you really have?
Dr. Craig Hillman is CEO and managing partner of DfR Solutions. Craig will be teaching a class on "True Design For Reliability" on March 30 during APEX/IPC Printed Circuits Expo in Las Vegas. He can be reached at chillman@dfrsolutions.com.