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Page Title:
MODIFICATION OF SOLDER-PLATED PRINTED WIRING CIRCUIT CARDS. |
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|  TM
11-5820-919-40-1
NOTE
4.
With the coining tool, coin
(flatten) the gold-plated copper wire
This procedure may be per-
ends to approximately 0.13 millimeter
formed only by personnel
(0.005 inch) thickness by 2.54 milli-
qualified as parallel gap
meters (0.100 inch) long by 0.38 milli-
welding operators.
meter (0.015 inch) wide (fig 3-6).
Technical personnel familiar with
1.
the function of the circuit must deter-
Braze the coined (flattened) wire
5.
mine the two points to which the jumper
to the printed circuit conductor pad
wire must be attached.
using the parallel gap welding machine
according to the following schedule.
Bend a 30-gage insulated gold-
2.
Single wires (fig 3-7) or double wires
plated solid-copper jumper wire to the
(fig 3-8) can be brazed to one circuit
Cut to required length.
designated
tabs.
pad.
Remove the insulation for a dis-
3.
tance between 6 and 7 millimeters (1/4
Encapsulate the jumper wire
as
6.
and 5/16 inch) from each end of the wire.
described in steps 7 thru 10.
DOUBLE
WIRE
SINGLE
WIRE
8 - 10 ms
8 - 10 ms
Weld
duration
0.66 - 0.68v
0.63 - 0.66V
Weld
voltage
1.3 - 2.3 kg (0-5 lb)
1.3 - 2.3 kg (3-5 lb)
Weld
force
0.38 - 0.50 mm
0.38 - 0.50 mm
Electrode
gap
(0.015 - 0.020 in.)
(0.015 - 0.020 in.)
WARNING
Hand wash-
taminated skin area.
ing facilities and eye wash
Use Freon with good ventila-
fountain should be provided.
Avoid prolonged or
tion.
Do not take internally.
repeated breathing of vapor.
Avoid contact with skin and
8.
Use any one of Narmco Epoxy Adhe-
Do not take internally.
eyes.
sive Kits No. 3135 listed in table 3-2.
If the frozen premix kit is used, allow
it to thaw to room temperature prior to
7.
Clean the area to be
encapsulated,
If either of the two-part kits is
use.
using
Freon TMC solvent.
used , mix approximately equal quantities
of Part A and Part B, using a disposable
Mix
thoroughly.
WARNING
aluminum cup for mixing.
Adhesives are irritating to the
Bond the jumper wire to the
9.
skin and eyes upon contact, and
printed wiring board by applying a spot
Use
may emit harmful vapor.
of adhesive (prepared in step 8) to a
only with adequate ventilation.
minimum diameter of 6.35 millimeters
Avoid all skin and eye contact.
(1/4 inch) at intervals of 5 centimeters
Use protective clothing such as
(2 inches).
It is not necessary to
Avoid
rubber gloves, apron and eye
encapsulate the brazed joint.
protection. Wash off immedi-
applying adhesive to any area that may
ately any accidentally con-
be subsequently soldered.
3-15
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