Figure 1: Remove solder mask
from the connecting circuit.
|
| 1. |
Clean the area.
|
| |
| 2. |
Remove the damaged section of circuit using
the knife. The damaged circuit should be trimmed
back to a point where the circuit still has
a good bond to the PC board surface.
|
| |
| 3. |
Use the knife and scrape off any epoxy residue,
contamination or burned material from the board
surface.
|
| |
| 4. |
Scrape off any solder mask or coating from the
connecting circuit. (See Figure 1).
|
| |
| 5. |
Clean the area.
|
|
Figure 2: Sample frame or
replacement conductors with
dry film adhesive backing.
|
| 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.
|
Select a replacement circuit with
film adhesive backing that most closely matches
the size of the conductor to be replaced. If a special
size or shape is needed it can be custom fabricated.
(See Figure 2). |
| |
| |
Note
New conductors are fabricated from
copper foil. The foil is plated on the top side
with solder and an epoxy bonding film is applied
to the bottom side.
|
|
Figure 3: Scrape off epoxy bonding film from solder joint
connection
area on back of new conductor.
|
| 8.
|
Before trimming out the new conductor
carefully scrape off the adhesive epoxy film from
the solder joint connection area on the back of
the new conductor. (See Figure 3). |
| |
| |
Caution
Scrape off the epoxy backing only
from the joint connection area. When handling
the new conductor avoid touching the epoxy backing
with your fingers or other materials that may
contaminate the surface and reduce the bond
strength.
|
| |
|
Figure 4: Cut out the new circuit.
Cut from the plated side.
|
| 9.
|
Cut out and trim the new conductor.
Cut out from the plated side. Cut the length to
provide the maximum allowable circuit overlap for
soldering. Minimum 2 times the circuit width. (See
Figure 4). |
| |
| |
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.
|
| |
|
Figure 5: Place the new conductor
in place using Kapton tape.
|
| 10.
|
Place a piece of Kapton tape over the top surface
of the new conductor. Place the new conductor
into position on the circuit board surface using
Kapton tape to help in alignment. Leave the
Kapton tape in place during the bonding cycle.
(See Figure 5).
|
|
|
| 11.
|
Select a bonding tip with a shape to match the
shape of the new conductor.
|
|
|
| |
Note
The bonding tip should be as small as possible
but should completely cover the entire width
of the new conductor.
|
|
|
|
Figure 6: Bonding System used to thermally bond dry film
adhesive
backed replacement conductors.
|
| 12. |
Position the circuit board so that
it is flat and stable. Gently place the hot bonding
tip onto the Kapton tape covering the new circuit.
Apply pressure as recommended in the manual of the
repair system or repair kit for 5 seconds to tack
the circuit in place. Carefully peel off the tape.
(See Figure 6).
|
| |
|
| 13. |
Gently place the bonding tip directly
onto the new circuit. Apply pressure as recommended
in the manual of the repair system or repair kit
for an additional 30 seconds to fully bond the new
circuit. The new circuit is fully cured. Carefully
clean the area and inspect the new circuit for proper
alignment.
|
| |
|
| 14. |
Apply a small amount of liquid
flux to the lap solder joint connection area and
solder the circuit foil jumper from the new conductor
to the circuit on the PC board surface. Use minimal
flux and solder to ensure a reliable connection.
Kapton tape may be placed over the top of the new
conductor to prevent excess solder overflow.
|
| |
|
| 15. |
Mix epoxy and coat the lap solder
joint connections. Cure the epoxy per Procedure
2.7 Epoxy Mixing and Handling.
|
|
|
| |
Caution
Some components may be sensitive to high temperature.
|
| |
|
| 16. |
Apply surface coating to match
prior coating as required.
|
| |
|
|
Figure 7: Completed repair.
|
|
Evaluation |
| |
|
| 1. |
Visual examination. |
| |
|
| 2. |
Measurement of new pad width and
spacing. |
| |
|
| 3. |
Electrical continuity measurement. | |
