Sony PS-FL1 - MOS IC Handling Precautions; Replacing MOS ICs Safely; CMOS IC Checking Precautions

Handling Precautions for MOS IC (1C105)
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
unrethane-polyester
cushion
1c
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.
VOM
(2.x 10,000 range}
3.
Equalize
any
potential
difference
between
the
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.
4. The following are effective methods for handl-
ing ICs that remove the potential difference
across the oxide layer.
@ Use a paper clip modified by soldering in a
wire braid insert.
wire braid
ii
soldered soldered
=
|
. Make sure. that there is
Fig. D no solder on the inside.
clip
partially conductive
. urethane-polyester .
Fig. E ceen or aluminum
oil
wire braid
clip
aly
its
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.).
PS-FL1/FL1C
PS-FL1/FL1C
_ Fig. G
@
Take
a
short
length
of
fine
bare
wire
and
wind
it
around
the
IC
so
that
it
shorts
all
the
pins
of
the
IC,
while
it
is
still
in
the
urethane-
polyester
cushion
or
aluminum
foil.
This
ensures
that
all
the
pins
are
at
the
same
potential.
fine bare wire
(stripped solid hookup
wire, etc.
partially conductive
urethane-polyester
cushion or aluminum
foil
@ When it is necessary to handle the IC with
the fingers, do not touch any pin, and hold
the IC at the ends of its plastic-package case
as shown in Fig. H.
Fig. H
Method of Mounting
Insert the IC while holding it with the modified
clip, and solder all the pins with the clip still
shorting the pins. (Similarly, solder all the pins
while the bare shorting wire is still wound
around them.). Remove the clip or the bare
shorting wire only after all the pins have been
soldered. :
Precaution while Checking C-MOS ICs
The C-MOS ICs (Complementary MOS) are MOS
ICs
that
have
their
output
sections
made
up
of
N-cluannel and P-channel push-pull stages to increase
their speed of operation. If the output terminal of
these
ICs
comes
into
contact
with
B+
or
B-
voltage,
then
the
FET
which
is
ON
at
that
time
will
either
become shorted or open.
This is valid for all the output sections that are
connected together by the interconnections. Even
the circuits that are physically separated (and not on
the same board) can be destroyed simultaneously.
-Example:
If this line is grounded, or touches
B+ or B- bus..., the output stage
of this IC will be destroyed.
Fig. |