BISv2 Reliability Study Progress Meeting - 1

<h1>BISv2 Reliability Study Progress Meeting - 1</h1>
<p>Present: M. Blaszkiewicz, L. Felsberger, C. Martin, I. Romera Ramirez</p>
<h2>Minutes</h2>
<p>The presentation highlighted the main outcomes of the quantitative analysis of the FMECA table.</p>
<h3>Reliability targets</h3>
<p>The BISv2 study is moving into a quite mature form where the reliability targets based on assumptions will become less relevant and focus will move towards the global reliability model. The model needs to have failure rate estimations "plugged in" from all of the studies of individual boards - for that reason it could not have been used earlier.  </p>
<p>Nonetheless, the presentation features a quick recap of the targets calculated for the CIBU board - which can be considered equivalent in many ways. </p>
<h3>Preliminary results</h3>
<p>These are based on the first iteration. They clearly show that the most dangerous end effect, i.e., blind failures, do not have a high failure rate. Remaining categories are also within the range of values established for other boards.</p>
<h3>Blind failures</h3>
<p>The following section of the presetation deals with the blind failures in more detail. Discussion of their locations in both, CIBU and CIBF led to many interesting take-aways:</p>
<ul>
<li>FITS number for the inverter: https://assets.nexperia.com/documents/quality-document/74LVT14D_Nexperia_Product_Reliability.pdf</li>
<li>RL1C stuck to position 5 is used for testing if the board is stuck to one state only. Impossible to fail until a number of things go wrong.</li>
<li>Optocoupler stuck to low signal: because there is another inverter that is not shown in the picture. Whether it’s a common problem or not - that’s another question.</li>
<li>Inverters role:
<ul>
<li>Isolation (preventing fault propagation),</li>
<li>Replenishing the power of the physical signal and reduce the power that is pulled from the output of the upstream devices (so that they are less stressed).</li>
</ul>
</li>
</ul>
<h3>Statistics</h3>
<p>The remaining part of the slides was devoted to the statistics presenting where each type of end effects originates most often from and other similar measures. They can be useful to diagnose problems with the study or assumptions made.  </p>
<h2>Actions</h2>
<ol>
<li>Whenever presenting FITS, provide an additional, more "palpable" metric so that the number is more transparent to people without reliaiblity background.</li>
<li>The next step in the study is to analyse the SFP, then CIBDS and then CIBFX.</li>
<li>When ready, use the (pessimistic) outcomes of the FMECA in the global model to predict overall reliability of BISv2.</li>
</ol>