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Page Title:
COMPONENT REPLACEMENT IN PLATED-THROUGH HOLES. |
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11-5820-919-40-1
On the reverse side of the board,
4.
3.
Feed rosin-cored solder to the
trim the lead as flush as possible.
pad-eyelet junction. When the solder
flows, follow the flow around the eye-
The opposite side of the board
5.
let with the solder until the entire
need not be soldered if the entire inner
joint is covered. Remove the iron
surface of the hole has been soldered.
immediately.
Use as small an amount of
solder as is practical and still cover
Repeat steps 2 thru 5 for each
6.
the entire joint.
lead
on the component.
Allow the soldered joint to cool
4.
7.
Encapsulate the component by the
at least 5 seconds without disturbing
the joint, as any disturbance during
method described in paragraph 3-33.
solidification may cause a fracture or a
REPAIR OF POLYURETHANE CONFORMAL
cold-solder
joint.
The polyurethane conformal
COATING.
5.
coating seals (encapsulates) the circuit
On the reverse side of the cir-
card and components from moisture and
cuit card, trim the lead as flush as
dust.
The coating should not be relied
possible.
upon to impart mechanical strength for
Discontinuities in the poly-
handling.
6.
Repeat steps 2 thru 4 for each
urethane conformal coating, such as
lead
on the component.
holes caused by test probes, areas
7.
Encapsulate the component using
scraped for component replacement or
etch repair, burned areas caused by the
the method described in paragraph 3-33.
soldering iron, and discontinuities
caused by an uncoated replacement com-
COMPONENT REPLACEMENT IN PLATED-
THROUGH HOLES.
Components may be
ponent itself may be repaired by per-
replaced in plated-through holes by
forming the following steps.
performing the following steps.
NOTE
Solvents used in this procedure
See paragraph 3-30 for compo-
are flammable and must be kept
from open flame, heat, and
nent clearance requirements.
Keep containers tightly
sparks.
1.
Make certain that all the poly-
closed and store them in a cool
place when not being used. The
urethane coating has been removed from
solvent must be used only in an
the pads on both sides of the circuit
adequately ventilated environ-
card.
ment.
Avoid breathing vapors
9
and repeated contact with skin.
Apply the well-tinned tip of the
Clean hands thoroughly before
soldering iron as close as possible to
smoking, eating, or drinking.
the component lead-pad junction.
3.
Feed rosin-cored solder to the
Prepare a mixture of polyurethane
1.
component lead-pad junction opposite the
conformal coating by following the manu-
When the solder flows,
soldering tip.
Solvent may be
facturer's
instructions.
follow the flow around the component
added as required.
lead-pad junction with the solder until
Remove the
the entire joint is covered.
Apply a thin, smooth, uniform
2.
iron immediately. Use as small an
coating with a small brush (1/2 inch) to
amount as is practical and still cover
all areas requiring coverage.
the entire joint.
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