I am having some difficulty with the Printed Circuit Board calculation. I read the FAQ and learned that this is a know issue (address in the question Expression from page 92). The problem now is that it appears the FIDES excel sheet has not been updated with this change. This can be seen when calculating a PCB with a mission profile consisting of two phases A and B. If I enter all the exact information into two copies of the excel sheet, just with the order of A and B reversed in the mission profile, I get two different answers for the failure rate. I appears the excel sheet is only using the Lambda O from the first mission profile phase. I have done the calculation myself and wish to confirm my answer.
PHASE On / Off tannual-phase Tambient Dtcycling qcy Nannual-cy Tmax-cycling RHambient GRMS-phase Saline pollution Industrial pollution Area of application Protection level A On 4,380 145 25.00 10.00 365 45 50 0.10 Low Urban area Inhabited Non-hermetically sealed B Off 4,380 120 4.00 14.00 365 22 70 0.01 Low Urban area Inhabited Non-hermetically sealed
The only part in my file is a Printed circuits, Class 1, Micro-via Technology, quantity 1, N Layer 1, N Mount 2
Pi Application is imposed at 3.2
Pi Ruggedizing is imposed at 1.7
Pi Induced is calculated at 5.0535162
Pi Part Manufacturing is imposed at 0.501576069066055
Results:
A before B excel sheet = 3,072.591
B before A excel sheet = 20.703
My results = 1496.404284
If you need any more information or want to see the excel sheets let me know
Thanks
Alyn
Dear Alyn,
I′m afraid you are right.
As there is no scheduled maintenance on this excel tool, I′m not sure we can help.
If you have T° over 110°C you may calculate the FR of PCB phase by phase (using 1 line life profile) and do the mean value manualy...
I′m sorry for this inconvenience.
Lambda