Figure 1: Remove the defective
edge contact and remove solder
mask from the connecting circuit.
|
| 1. |
Clean the area.
|
| |
| 2. |
Remove the defective edge contact and a short
length of the connecting circuit. Heat from
a soldering iron will allow the old contact
to be removed more easily. (See Figure 1).
|
| |
|
| 3. |
Use the knife and scrape off any epoxy residue,
contamination or burned material from the board
surface.
|
| |
| |
Caution
Abrasion operations can generate
electrostatic charges. |
| |
| 4. |
Scrape off any solder mask or coating
from the connecting circuit. (See Figure 1). |
|
Figure 2: Select a replacement
contact that matches the missing contact.
|
| 5. |
Clean the area. |
| |
|
| 6. |
Apply a small amount of liquid flux to the connection
area on the board surface and tin with solder.
Clean the area. The length of the overlap solder
connection should be a minimum of 2 times the
circuit width.
|
| |
|
| 7. |
The area for the new edge contact on the board
surface must be smooth and flat. If internal
fibers of the board are exposed or deep scratches
exist in the surface they should be repaired.
Refer to appropriate procedure.
|
| |
|
| 8. |
Select a new edge contact that most closely
matches the edge contact to be replaced. (See
Figure 2).
|
|
Figure 3: Cut out the new edge contact.
|
| 9. |
Cut out and trim the new edge contact. Cut out
from the plated side. Cut the length to provide
the maximum allowable joint if lap soldering.
Minimum 2 times the circuit width. Leave the
new edge contact extra long. The excess material
will be trimmed after curing. (See Figure 3).
|
| |
|
| |
Note
The new replacement land may be trimmed
from copper sheet. |
| |
|
| 10. |
Mix the epoxy and apply a small amount to the
surface where the new contact will be placed.
|
|
Figure 4: Place the new edge
contact in place using Kapton
tape.
|
| 11. |
Place a piece of Kapton tape over the top surface
of the new edge contact. Position the new edge
contact on the circuit board surface using the
Kapton tape to aid in alignment. (See Figure
4).
|
| |
|
| |
Note
Allow the edge contact to overhang the
edge of the circuit board. Leave the Kapton
tape in place during the bonding cycle.
|
| |
|
| 12. |
Cure the epoxy per Procedure 2.7
Epoxy Mixing and Handling. |
| |
|
| |
Caution
Some components may be sensitive
to high temperature. |
| |
|
| 13. |
After the epoxy has cured, remove the Kapton
tape used for alignment. Carefully clean and
inspect the new pad for proper alignment.
|
| |
|
| |
Note
Additional epoxy can be applied around
the perimeter of the new edge contact to provide
additional bond strength
|
| |
|
| 14. |
If the new edge contact has a connecting circuit
apply a small amount of liquid flux to the lap
solder joint connection area and solder the
circuit from the new edge contact to the circuit
on the circuit board surface. Use minimal flux
and solder to ensure a reliable connection.
Kapton tape may be placed over the top of the
new edge contact to prevent excess solder overflow.
|
| |
|
| |
Note
If the configuration permits, the overlap
solder joint connection should be a minimum
of 3.00 mm (0.125") from the related termination.
This gap will minimize the possibility of simultaneous
reflow during soldering operations. Refer to
7.1 Soldering Basics.
|
| |
|
| 15. |
Remove the Kapton tape and clean
the area. |
| |
|
|
Figure 5: File overhanging piece
of new edge contact to blend with existing bevel.
|
| 16.
|
Trim the extending edge of the new edge contact
with a file. File parallel to the beveled edge
until the excess material has been removed.
(See Figure 5).
|
| |
|
| 17. |
If sealing the lap solder joint connection is
required, mix epoxy and coat the lap solder
joint connections. Cure the epoxy per Procedure
2.7 Epoxy Mixing and Handling.
|
| |
|
| 18. |
If plating is required refer to
appropriate procedure. |
| |
|
| 19. |
Apply surface coating to match
prior coating as required. |
|
Figure 6: Completed repair. |
|
Evaluation |
| |
|
| 1.
|
Visual examination, measurement
of new pad width and spacing. |
| |
|
| 2. |
Electrical continuity measurement. |
|
