MIL-PRF-19500/421G
4.3 Screening (JANTX and JANTXV levels only). Screening shall be in accordance with table IV of
MIL-PRF-19500, and as specified herein. The following measurements shall be made in accordance with table I
herein. Devices that exceed the limits of table I herein shall not be acceptable.
Screen (see table IV
Measurement
of MIL-PRF-19500)
JANTX and JANTXV levels
3c
Thermal impedance (see 4.3.2)
9
Not applicable
10
48 hours minimum
11
ICBO2 and hFE5
12
Burn-in (see 4.3.1) 80 hours minimum
13
Subgroup 2 of table I herein;
ĆICBO2 = 100 percent of initial value or 25 nA dc; whichever is greater for the 2N3838.
ĆICBO2 = 100 percent of initial value or 5 nA dc; whichever is greater for the 2N4854,
2N4854U.
ĆhFE5 = 15 percent of initial value.
14
Required
4.3.1 Power burn-in conditions. Power burn-in conditions are as follows: VCB = 10 - 30 V dc TA = room ambient
as defined in the general requirements of MIL-STD-750, (see 4.5).
2N3838:
PT = 175 mW each transistor (350 mw total device).
2N4854:
PT = 300 mW each transistor (600 mW total device).
2N4854U:
PT = 300 mW each transistor (600 mW total device).
NOTE: No heat sink or forced air-cooling on the devices shall be permitted.
4.3.2 Thermal impedance (ZθJX measurements). The ZθJX measurements shall be performed in accordance with
method 3131 of MIL-STD-750.
a.
IH forward heating current................................... 200 mA.minimum.
b.
IM measurement current ..................................... 5 mA.
tH heating time.................................................... 25 -30 ms.
c.
tMD measurement delay time .............................. 60 µs maximum.
d.
e.
VCE collector to emitter ...................................... 10 V.
The maximum limit for ZθJX under these conditions are ZθJX (maximum) = 45°C/W.
7
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