Former APPLICATION NOTES FOR MIL-PRF-55681 that are no longer applicable

The NPSL application notes for multilayer ceramic capacitors are being amended (May 2013) to reflect the following recommendations from a NASA Engineering & Safety Center (NESC) report ^[1] on the subject of low voltage failure phenomenon of ceramic capacitors:

R-1. NASA guidelines should be amended to remove any requirements to perform Humidity Steady-State Low Voltage (HSSLV) test as an add-on lot acceptance test for MIL QPL MLCCs.

R-3. NASA guidelines should be amended to remove restrictions on MLCCs rated at less than 100 V when used in low voltage applications.

Reference:

[1] “Multilayer Ceramic Capacitors (MLCC) –Low Voltage Failure (LVF) Phenomenon” NASA/TM-2010-216852, NESC-RP-07-056, October 2010, NASA Engineering and Safety Center (NESC)

Per the Recommendations of the Above Referenced NESC Report, the Following Application Notes Are No Longer Applicable to Parts Purchased in Accordance With MIL-PRF-55681

2) As an alternative to MIL-PRF-123, for Level 1 applications at >= 10 Vdc, MIL-PRF-20, MIL-PRF-39014, or MIL-PRF-55681 capacitors can be used in accordance with the type, value and failure rate guidelines shown in the tables.

3) As an alternative to MIL-PRF-123, for Level 1 low voltage applications (< 10 Vdc), MIL-PRF-20, MIL-PRF-39014, or MIL-PRF-55681 capacitors can be used, if capacitor rated voltage is at least 100 Vdc and flight lots are subjected to lot sample testing per Group B Subgroup 2 of MIL-PRF-123 (Humidity, Steady-State, Low Voltage).  These recommendations stem from concerns about the low voltage failure mechanism which has been observed to occur in multilayer ceramic capacitors.  In low voltage applications, multilayer ceramic capacitors with thin dielectrics and/or large voids, delaminations, inclusions, microcracks and other defects, may develop low and unstable insulation resistances.

4)  For Level 2 applications at >=10 Vdc, capacitors can be used in accordance with the type, value and failure rate guidelines shown in the tables.

5)  For Level 2 low voltage applications (< 10 Vdc), capacitor rated voltage should be at least 100 Vdc.  Alternatively, parts rated at less than 100 Vdc can be used if flight lots are subjected to lot sample testing per Group B Subgroup 2 of MIL-PRF-123 (Humidity, Steady-State, Low Voltage).  These recommendations are prompted by low voltage failure concerns (see note 3).