SRC Forum - Message Replies

Forum: Reliability & Maintainability Questions and Answers

Topic: Reliability & Maintainability Questions and Answers

Topic Posted by: Reliability & Maintainability Forum (src_forum@alionscience.com )
Organization: System Reliability Center
Date Posted: Mon Aug 31 12:47:36 US/Eastern 1998

Original Message:

Posted by: Murali (murali_913@yahoo.com )
Date posted: Sun May 16 7:26:21 US/Eastern 2004
Subject: Quality factor for Resistors
Message:
Can some body help me out please? I am working for resistor Reliability prediction methods. I am following MIL-HDBK 217F. In the Reliabiltiy Prediction Calculation it is mentioned that Quality Factors for resistor as S,R,P,M. Can you please give some idea about these abbreviations. Thanks in advance.

Reply:

Subject: Resistor Quality Factors
Reply Posted by: bwd (bdudley@alkionscience,con )
Organization: RAC
Date Posted: Mon May 24 15:14:13 US/Eastern 2004
Message:
You should review MIL-PRF 199 the resistor military specification for specific definitions. In general the letters apply to the screening or life tests that are performed on the military designated parts. S is the best and M is the least. These quality factors only apply to military devices with three letter designations. For commercial parts, MIL-HDBK-217 says that you must apply a factor of 10 to the analysis. Since MIL-HDBK-217 is obsolete, you should consider the use of a more up to date analysis technique such as PRISM, as you will find that the resistor and capacitor analysis is going to dominate the end result and give you a false or pessimistic picture of the hardware.