Forum: Reliability & Maintainability Questions and Answers
Posted by: IC Date posted: Fri Aug 4 10:26:58 US/Eastern 2000 Subject: Failure rate of Fibre Optic Cables Message: Can anybody provide me with a generic failure rate of fibre optic cables (single core and multi core)or a good source of information that will allow me to calculate a failure rate. Thanks in advance.
Posted by: Ian (ian.carmichael@kymata.com ) Organization:Kymata Ltd Date posted: Thu Aug 3 7:50:26 US/Eastern 2000 Subject: Burn-In Message: When performing burn-in on a new device I would like to know if there is a method of calculating at which point the burn-in should cease i.e. the point where "infant mortality" becomes "constant failure rate. Can it be calculated theoretically or does it require empirical data. Thanks in anticipation
Posted by: Sam Date posted: Mon Jul 31 18:37:43 US/Eastern 2000 Subject: Coffin-Manson Eq. Message: We're using Coffin-Manson equation to calculate the acceleration factor (AF) of solder joint (failure mechanism is thermal fatigue). The AF is only related to temperature range. The question is: if the temperature transition rate affects the AF? If so, what's the equation? In addition, are there any other equations to calculate the AF for the above condition? Thanks in advance! Sam.
Posted by: Ian Carmichael (ian.carmichael@kymata.com ) Organization:Kymata Ltd. Date posted: Mon Jul 31 6:56:17 US/Eastern 2000 Subject: Reliability Sources Message: I would be grateful if somebody could provide me with information relating to generic failure rates of Epoxy resins and semiconductor wafer chips. Thanks in anticipation.
Posted by: Roy Shepard (searand@ieee.org ) Organization:Inex Vision Systems, Inc. Date posted: Thu Jul 27 15:19:35 US/Eastern 2000 Subject: Defective 10K RCO7 resistors from Taiwan Message: Industrial and Electronic Manufacturers and other end users are alerted to the presence of defective type RCO7, 10K ohm, 1/4 watt, 5%, Carbon Composition resistors entering this country from Taiwan. These resistors are identified by a shiny "wax" seal on both ends of the body of the RCO7s. Further examination under a powerful magnifying glass or microscope will reveal the presence within the wax seal of an as yet unidentifed contaminant, currently believed to be organic, scattered randomnly thorugh out the wax. When these defective RCO7 resistors are installed on a CCA and processed through a standard wave solder process, the "wax" seal melts. By a process believed at present to thermally outgass the wax and/or to thermally generate a chemical reaction with the carbon composition, the result is the same. Nine (9) out of every ten (10) of the 10K resistors INCREASE their resistance by a measured 8 to 16 percent out of tolerance. Manual resoldering has disclosed that the heat from the manual soldering process will cause, on average, two (2) out of every ten (10) resistors to fail out of tolerance. Circuit Card Assemblies (CCAs) containing these defective 10K resistors in timing circuits have been observed to drift out of spec as the CCA heats up. Six (6) additional RCO7 resistance values, described above have been identified in stock to date and are awaiting testing.
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