Forum: Reliability & Maintainability Questions and Answers
Posted by: Sathees kumar Ramamoorthy (satheeskr@ctd.hcltech.com ) Date posted: Thu Apr 3 9:26:44 US/Eastern 2003 Subject: Derating Message: I'll be grateful if anybody could help me in solving this issue and other issues that I have posted in this forum. Question :" Whether we have to use the Derated power as the Rated power if we are using the device above the ambient temperature". For eg., 0.0088 W/'C is the derating to be done for a diode whose rated power is 0.65 W (at 25'C). If I'm using the device at 70'C, the derated power comes to 0.254 W which is 71% derating. Now whether I have to use Derated or Rated power for my stress calculation.
Posted by: Sathees kumar Ramamoorthy (satheeskr@ctd.hcltech.com ) Organization:HCL Technologies Date posted: Thu Apr 3 9:28:42 US/Eastern 2003 Subject: Reg - MIL HDBK 217FN2 Message: Dear Sir, I would like to be get clarified about three issues that I have faced in MIL HDBK 217FN2.
2. For computing Electrical stress factor(Pi S) (page 6.3) for Diodes(Low Frequency) Voltage stress ratio is required. It is mentioned in MIL HDBK 217FN2 that "Voltage is diode reverse voltage". I would like to get it confirmed that Voltage Applied and Voltage Rated both refer to Reverse voltage.
3. Power Dissipation is required for computing Power factor(Pi P) (page 9.2) for Resistors. Does this Power dissipation refer to Rated or Actual Power dissipation.
Posted by: Heu Yon Chung (heu_yon_chung@yahoo.co.uk ) Date posted: Sat Mar 22 2:45:28 US/Eastern 2003 Subject: Chinese Standards B299 Message: I am looking for a copy of this standard to read. Can anybody help. thank you
Posted by: Sathees kumar Ramamoorthy (satheeskr@ctd.hcltech.com ) Date posted: Fri Mar 21 13:49:56 US/Eastern 2003 Subject: FMEA Message: Hello, Is it neccessary to do FMEA pin wise for a 100 pin PLD or could we limit upto the failure modes given in the FMD97 tool. I'm also not clear whether failure mode of chip will also include short/open circuit of its input/output pins or only modes like manufacturing defects, internal short/open. Please clarify.
Posted by: Richard Smith Date posted: Tue Mar 18 10:22:38 US/Eastern 2003 Subject: CHR Capacitor Shelf Life/Aging Message: Can anybody please refer me to a source of information on Capacitor Aging and Shelf Life (aging mechanisms and reliability of older components). I am particularly interested in CHR capacitors (fixed, metallized, plastic film dielectric). Thanks in advance.
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