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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

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Original Message:

Posted by: Gerd Jonas (jonas.gerd@litef.de )
Organization:LITEF
Date posted: Wed Oct 11 3:20:33 US/Eastern 2000
Subject: MIL-HDBK-217F notice 2 section 16
Message:
In the past our printed circuits boards are plated through holes tech. The new standard is now SMD technologie. If you calculate the failure rate for the interconnection, for the SMD tech. the failure rate is much lower. Were I have to implemented the number of circuit planes? Is it possible to calculate the failure rate for SMD tech in differend modes? please answer as soon as possible. regards Gerd Jonas


Reply:

Subject: MIL-HDBK-217F notice 2 section 16 for SMT
Reply Posted by: Nathan Holzhauer (nholzhauer@alionscience.com )
Organization: RAC
Date Posted: Thu Oct 12 16:57:44 US/Eastern 2000
Message:
No, the complexity factor (pi-sub-C) in the SMT assembly analysis section (16.2) of MIL-HDBK-217F not2 takes care of the number of planes (modes) involved. All SMT devices for a given circuit board are evaluated together. Which plane each device connects to doesn't affect the analysis. In the event that through hole and SMT methods are combined, use the individual computations as stated at the beginning of section 16.1.


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