Hi Justin, Here's what we do: 1) Fiber optic assembly: Bellcore TR-332 2) Military Assembly: Mil-Std-217F 3) An Other Assembly: Parts count method using supplier data for active components and any passives that are available. Use Bellcore as first choice for any not available, use 217 last. Here's some other info to keep in mind when doing reliability estimates. First, many people are skeptical of these methods, but I still find there's value in them. In the least, it opens up lines of communication between you and the supplier so that you can be aware of limitations and potential/past problem areas. Second, if you use supplier data, be sure to adjust for temperature and confidence levels. Many suppliers will publish 25 C failure rate numbers and Bellcore asks for 40C. As you probably know, the higher the temperature, the higher the failure rate and lower MTBF. We also like to use 90% confidence, but you will often find 60% confidence commonly used. The higher the confidence, the higher the failure rate. Thirdly, Bellcore (Telcordia) TR-332 now costs $1,000. Good luck trying to sell management on that. Some links: http://telecom-info.telcordia.com/site-cgi/ido/index.html http://www.enre.umd.edu/mainnojs.html http://www.quality.org/html/reliable.html Glenn Justin Braime <[log in to unmask]> Wrote: | | What is the best method for calculating an MTBF figure for your average, run of the mill, electronic | assembly? | Are Bellcore TR-332 and MIL-HDBK-217 still the most current standards in this area, or has IPC come | out with something? | | my humble thanks... | | Justin Braime | ------------------------ | Process Engineer | Compuspec Industries Ltd | Auckland, New Zealand | [log in to unmask] | | ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ##############################################################