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Handling Precautions for MOS
ICs
Generally, the insulation resistance of the oxide
layer in MOS IC structures is very high, and the oxide
layer is very thin.
Because of this, it is possible that
the static voltages usually present on clothes and the
human
body
will be enough
to generate a potential
difference
across the insulator, high enough to cause
a breakdown of the insulating layer.
The following precautions should be taken while
handling these ICs.
(Particular care should be taken under conditions
of low humidity.)
Precautions in Replacing MOS
ICs
1.
Store new ICs by inserting them into a urethane-
polyester cushion (which is somewhat
conduc-
tive), or wrapping
it in aluminum
foil, so that
all the pins are at the same potential.
(The ICs should be stored in that manner until
mounted
on the circuit board.)
Fig. A
partially conductive
Ee
A EROIESTEE
shion
cu.
IC
"gs
Fig. B
aluminum
foil
2.
Check the soldering iron for possible power-line
leakage
current.
Make
sure
that
there
is no
leakage path by connecting an ohmmeter to the
tip of the soldering iron and the plug as shown
in Fig.C.
If there is a leakage path, use some
other soldering iron.
vou
(2.x 10,000 range)
3.
Equalize any potential difference
between th.
clothes, the tools in use, the work
bench, the.
set being worked
on, and the packaged IC by
touching them all in succession with the hands
or a conductive
wire or tool.
wire braid insert.
wire braid
soldered
soldered
Make sure that there is
no solder on the inside.
clip
partially conductive
urethane-polyester
Fig. E
cushion or aluminum
foil
wire braid
clip
Make sure that all the pins are in
contact with the wire braid (all
:
the pins will then be at the same
Fig. F
potential. ).
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i
i.
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