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Copyright © Microsemi Corp.
Rev. 1.0 8/99
MicroNote 060
MIL-PRF-19500 Qual Chips
vs. MIL-PRF-38534 Qual Chips
Over the last few years, there has been
some confusion ov er the most viable wa y
that discrete chips can be purchased for use
in highly reliable hybrid and MCM
systems. The standard method used for
years has been to purchase discrete chips
that were qualified to the requirements
summarized in MIL-PRF-38534. There
are two qualif ication levels def ined in the
document. The f irst is Class H for the
standard military quality le vel and the
second is Class K that is the highest
reliability lev el and is intended f or space
applications. The discrete community,
while partnering with DSCC, decided that
if two similar qualification levels for chips
were established in MIL-PRF-19500, it
would allow the hybrid manufacturers to
buy chips off the shelf that were qualif ied
either to a MIL level or a space lev el. To
keep the identification similar to the
requirements of MIL-PRF-38534, the same
designators were used and thus the
beginning of JANHC and JANKC product
levels. When the pro gram was initially
started, man y hybrid manuf acturers were
reluctant to use the ne wly formed
classif ications because the requirements
were dif ferent than those of MIL-PRF-
38534. To resolve those concerns, and to
add more meaningful requirements to the
MIL-PRF-19500, the specification was
rew ritten in 1997. MIL-PRF-19500 details
the requirements for chip qualifications
and they are equal to or surpass all the
requirements of MIL-PRF-38534.
There are many adv antages for the MCM
and hybrid manufacturer to use chips
qualified to MIL-PRF-19500. Both Lot
Acceptance Testing (LAT) requirements
are compared below.
Other advantages to using the MIL-PRF-
19500 qualified dice are:
1) Dice are in stock with the LAT
completed.
2) Less paperwork for the hybrid
manufacturer - no source control
dra wing.
3) Topography of each qualified chip is in
the performance specification.
4) Metal type and thickness listed in the
performance specification.
5) Standardization
6) More reliable products.
7) The " no-rew or k" rules of MIL-PRF-
19500 apply.
Listed ar e some scenarios and anecdotes
that should be of concern.
1) - Prior to the re write of the c hip
requirements in MIL-PRF-19500 in 1997,
Microsemi PPC had qualified a dif fusion
lot of mid power transistor chips as
JANKC 2NXXXX. Over the course of
more than a year , four different customers
bought those same dice but they had to
hav e them qualified to MIL-PRF-38534.
Four new LAT's we re processed for the
diffe rent customers from the already
qualified diffusion lot. The cost to each
customer was 12 ex tra weeks plus a price
that ranged from 1.3 to 4.2 times the
JANKC standard price.
2) - A hybrid facility in the North East was
b uying dice from a c hip distrib utor. The
part number was a common signal bipolar
transistor. The chip distrib utor ran the Lot
Acceptance Testing and tested the de vices
to the static tests as required by MIL-PRF-
38534. The hybrid manufacturer was
appalled at the performance of the devices.
No dynamic tests were done and the
frequency response and the switching
times were not close to the performance
specification requirements.
3) - A hybrid manufacturer had been using
a po wer device manufactured by a specific
JANS manufacturer for years and had been
very satisfied with the product. She had
characterized the chips on radiation and
wanted the same product for the lifetime of
the program. She then ordered dice from a
distributor and specif ied the manuf acturer
and Class K. The manuf acturer also had a
contracted wafer f acility that manufacture d
only commercial product. The chip
distrib utor bought wafers from the
contracted wafer f ab, pulled three dice per
wafer and ran a K level LAT. The hybrid
manufacturer not only sa w distrib utions
that were erratic compared to the product
that she was used to, b ut the lot f ailed
radiation testing.
For a complete version of
MicroNote 060, please visit our
web site at:
www.microsemi.com
by Carlton B. Mowry
Microsemi PPC
cmowry@microsemi.com
Table A Table B
JANHC
MIL - P RF 38534
CLASS H
1) DSC C a pproved fac ility No r e qu ir ement
2) HTRB on LAT None
3) Burn -in per f or med None
4) LAT amor tized in
whole lot
LAT c harged
per or der
5) Meets all r equirement s
of MI L- P RF - 38534.
Does not meet
requirement s of
JANHC.
6) Dynamic tests
performed
No dyna mic t e st
requirements
7) Die shear test ed No di e shear test
JANKC
1) Die manufactur er is
JANS qual ified
No requir ements on
the wafer fab
2) JANS process
monitors r equir ed
No requir ements
3) Electrically meet
19500 Per f. S pec.
Could be to
dist r ibutors dat a
s heet
4) Must pa ss dynamic
tests
No dynamic t est
requirem ents
5) DSCC must appr ove
process c hang es
Process changes
can oc c ur
6) Die shear per formed No die shear
requirem ent
MIL-P RF 38534
C LASS K