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A publication of the National Electronics Manufacturing Center of Excellence - page 11 / 12





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Reliability Concepts

(continued from page 6)

any phase of the bathtub curve. A β<1 models a failure rate that decreases with time, as in the infant mortality period. A β=1 models a constant failure rate, as in the normal life period. And a β>1 models an increasing failure rate, as during wear-out. There are several ways to view this distribution, including probability plots, survival plots and failure rate versus time plots. The bathtub curve is a failure rate vs. time plot. The Weibull distribution is given by Equation 6-1:

Equation 6-1: Weibull distribution equation.

Figure 6-2: Results of various βs on the Weibull analysis.

The results of various βs on the Weibull analysis can be seen in Figure 6-2. Notice how, if all curves are combined, the resultant graph is similar to a bathtub curve.

The EMPF not only uses Wiebull analysis routinely but also teaches the process as a part of our electronics manufacturing training. This distribution, for example, allows modeling to be done with a minimal amount of error. At the EMPF we engage our students with practical applications on how to utilize the various forms of reliability modeling.

For more information on engineering and other training classes, please contact Ken Friedman at 610.362.1200, extension 279 or via email at kfriedman@aciusa.org.

Michael Barger | Senior Materials Engineer

Upcoming Courses

Chip Scale Manufacturing

Lead Free Manufacturing

February 16 -18

February 22-23

Receive hands-on training utilizing advanced packaging equipment in the on-site demo lab. Identify and perform critical process steps when manufacturing ball grid arrays (BGAs), micro-BGAs, flip chips and chip scale packages. Identify and implement process control methods and practices when manufacturing assemblies with advanced packages.

Electronic manufacturers must consider new processes, materials and techniques to remove lead from electronic assemblies. This course introduces participants to the technical challenges of developing and implementing lead free soldering into an electronics manufacturing production environment and provides application specific solutions to address issues.

CONTACT THE REGISTRAR VIA: phone at 610.362.1295, email at registrar@empf.org or online at www.aciusa.org/courses



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