Non-Operating MIL-HDBK-217E

Nonoperating Prediction Using MIL-HDBK-217E

RAM Commander supports a modified version of the computation methodology defined in MIL-HDBK-217E, Notice 1 (draft). The modification is that for Item types not listed in 217E, RAM Commander uses data from RADC-TR-85-91. Calculations using this method produce a storage (nonoperating) failure rate and a cycling failure rate.

Cycling reliability for a component is computed as a function of storage (nonoperating) reliability using the following formula:

λcycling = K λstorage

where K is a multiplier. The table below presents default values for K for the following Item types:

Item type	K
IC-Digital	20
IC-Analog	20
IC-Memory	20
LF and HF Transistor	50
LF and HF Diode	83
Resistor	63
Capacitor	160
Inductive transformer	750
Inductive coil	380

Item types not appearing in this table have a default K value of 0.

You may change default values on the reliability prediction method data screen for each particular component:

Using RAM Commander’s Default Manager, you can change the default values for the K multiplier for each component type (and not for each particular component, as above).

To modify default K values:

1.	Activate the Product tree view.

2.	From the Project menu, select Default Manager; the Default Manager list opens.

3.	Make selections in the Item type list box.

4.	Click on a specific component type in the list, and from the Item menu, select Edit; the processor dialog box opens.

5.	Enter a default multiplier value in the K Cycling field.

6.	Choose OK.

RAM Commander normally applies the default value when computing cycling reliability for components of the selected technology. If you enter a specific value in a component’s processor dialog box, RAM Commander uses it instead of the default.

Cycling Reliability Reports

RAM Commander uses the value in the K Cycling field to compute cycling reliability. This reliability value appears on a special report which you can produce using the following procedure.

To report cycling reliability values:

1.	Recalculate the project.

2.	From the Reports menu, select Tree; the Report Selection dialog box opens.

3.	In the Type list box, select Storage and Cycling.

4.	Enter values for other fields as necessary, and choose OK.

RAM Commander displays the report in a report window (see sample on the next page).