MIL-PRF-23419/12E
Thermal vacuum: Fuses shall be mounted in suitable mount sockets. The fuses shall then be placed in
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a vacuum chamber and the chamber evacuated to a pressure of 5 x 10 torr maximum. The
temperature of the fuse mount shall be controlled such that the temperature of the fuses, as measured
with a thermocouple mounted on the fuse body, is maintained at +125°C ±3°C for a period of 48 +4, -0
hours, while 90 percent of the 25°C rated current is flowing through each fuse. At the end of the 48
hour exposure and while the fuses are at the test temperature and pressure, one-half of the samples
shall be given an overload interrupt test at 400 percent of their rated current. The fuses shall then be
removed from the chamber and the remaining fuses (not blown) measured for DC resistance as
specified in MIL-PRF-23419. The change in resistance shall not exceed ±10 percent of the initial value.
Quality conformance: With the exception of the overload characterization test and dielectric
withstanding voltage test, the following tests shall be conducted on 100 percent of the units, in the order
shown, and shall replace the group A tests referenced in MIL-PRF-23419. Nonconforming units shall
be removed from the lot. The lot shall be considered rejected if it exceeds the allowable PDA of 5
percent for the thermal shock and burn-in tests combined.
a.
Precap inspection performed at 10X magnification as specified herein.
b.
Visual and mechanical inspection; screen for the following defects:
(1)
Cracks in the plastic molded housing (critical at lead egress area).
(2)
Insufficient plastic fill (critical at lead egress area).
(3)
Excessive plastic flash (part out of dimensional tolerance).
c.
Thermal shock as specified herein.
Burn-in: 168 hours at rated current and ambient air at +25°C +3°C, -0°C.
d.
DC resistance in accordance with MIL-PRF-23419.
e.
f.
Overload characterization: Each fuse lot shall be sampled to assure that overload interrupt
times shall fall within the limits as specified in table I. Each lot shall be truncated to form an
inspection lot based upon the final voltage drop as measured after the completion of burn-in.
The manufacturer shall subject samples selected from the extremes of the truncated population
to overload interrupt testing to ensure that overload interrupt times are as specified in table I. A
minimum of 20 fuses shall be selected from the extremes of the population and subjected to 250
percent, 400 percent, and 600 percent overload interrupt testing.
Radiographic inspection in accordance with method 209, MIL-STD-202, two views (0° and 90°).
g.
Inspection criteria shall be as specified herein.
h.
Visual and mechanical inspection in accordance with MIL-PRF-23419 at 10X magnification.
i.
Dielectric withstanding voltage shall be performed as specified herein. A sample of fuses shall
be randomly selected in accordance with the zero defect sampling plan of MIL-PRF-23419
(group B column). If one or more defects are found, the lot shall be rejected.
Part or Identifying Number (PIN): The PIN shall be derived from table I. An example of a complete
PIN designation: FM12A72V1/2A.
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