Textron Cessna 182S - Page 138

CESSNA
AIRCRAFT
COMPANY
MODEL
182/T182
WIRING DIAGRAM
MANUAL
CAUTION:
THERMAL
SHUNTS (HEAT
SINKS) SHOULD
BE USED
TO
PREVENT
EXCESS
HEAT
FLOW
TO ADJACENT
PRESOLDERED
JOINTS
OR HEAT SENSITIVE PARTS.
G.
Apply the soldering
iron tip to the connection
in such a manner
that soldering temperature
will be
reached
in the minimum
time.
Refer to Figure
203 and Figure
207 for
examples of acceptable
and
unacceptable
solder
joints.
(1)
Solder should
be applied to
the joint when
the temperature
of the joint
will readily melt
the solder.
(2) Solder should
not be
applied at the
junction of the
soldering iron
tip and the
parts to be joined,
nor shall
solder be melted
on the soldering
iron
tip and allowed
to flow over
the parts to be
joined.
(3)
Apply sufficient
solder
to cover
the conductor.
(a) A concave
fillet should be formed
between the center
of the conductor
and the terminal.
(b) The
contour of the terminal
and the conductor
should not be completely
obscured
by solder.
When
the conductor is
completely covered
by solder, or when
a solder spike
or other
excessive
amount piles upon
the terminal that could
touch some adjacent
component,
the
excessive solder must be removed.
(c) Wicking of solder
in stranded wires should not extend
to the insulation.
(4) Cold solder joints
require reheating and reflowing
of the solder.
(5) Rosin-base
flux residue
need not
be removed,
when required
to be removed
use appropriate
solvent.
(6) After the connection
has cooled, residue
of nonrosin base
flux should be completely
removed
to prevent
corrosion.
H. Thermal
shunting should be
used on all solder connections
where heat
flow to adjacent presoldered
joints or heat
sensitive components
could occur. If
in doubt, use a heat
sink. Refer to Figure
206.
(1) Thermal
shunts
(heat sinks) shall
preferably
be made of copper
for good
heat conductivity.
They
should be
large enough
to give adequate
thermal
protection, while
causing
as little interference
to soldering
as
possible.
(2)
Attach the thermal
shunt (heat
sink) as close as
possible to the
joint to be soldered.
(3) Several
smaller thermal shunts (heat sinks) may be
used in place of a large unit and often serve
a double
purpose of eliminating
movement
of wire leads preventing
cold solder
joints.
I.
Pretinning of wires
before soldering.
(1) All
portions of stranded
wires which come in
contact with the area
to be soldered can
be tinned
by dipping
the fluxed wire
in a solder
pot or by use
of a soldering
iron.
(2) The
tinning shall
extend only far
enough onto
the wire to take
full advantage
of the area
coming
in contact
with the connector
or solder joint.
(3)
A thin coating
of solder
shall be applied
to all portions
of the conductor
wire coming
in contact
with the solder
joint area. The solder
shall penetrate to
the inner strands of
stranded conductors.
To permit inspection
for nicks or cuts
at the point of insulation
termination,
solder and wicking
shall not
conceal the individual
outer wire strands.
A thermal shunt
may be used to prevent
this
occurrence.
(4) The distance
between
the end of the
wire insulation
and the beginning
of the tinned
portion shall
be
no less than 1/2 the outside
diameter of wire insulation.
(5)
Part leads
or terminals
that are pretinned
by the
part manufacturer
will not
require further
tinning unless
corrosion has occurred
during storage.
Corrosion products
shall be removed
by pretinning
of the
lead or terminal.
(6) Parts which
are dip-tinned
shall be
held in the solder
container
(Pot) until a bright,
continuous,
tightly adhering coat
of solder is formed.
The solder pot shall
operate at a temperature
20°F to
50°F
above the liquidus
of the solder alloy
used. The molten solder
shall be of such
volume that
the temperature
will not be
reduced more than
10°F when
parts are dipped.
J. When soldering
components on
printed circuit boards,
the old component must
be removed and the
solder cleaned from the holes
before installing the new
component.
(1) When
lead wires must be
bent to install a component,
the minimum
distance to the start
of the
bend
is two lead
wire diameters,
but
not less than
0.030 inch.
Refer to
Figure 202.
(2)
Components
with the value
stamped on one
side, the leads
should be bent
so the value will
be
visible when installed;
if practical.
20-10-03 Page 204
© Cessna Aircraft
Company
Mar 1/2004