IPC-7721(S).pdf - 第97页
EVALUATION 1. Visual examination for alignment and overlap of wire. 2. Electrical tests as applicable. IPC-7721 Number: 4.2.5 Revision: Date: 2/98 Subject: Conductor Repair , Through Board Wire Method P a g e3o f4
CAUTION
Review conductor diagrams to be sure no surface or internal conductors will be
damaged or shorted.
10. Drill through the board, either adjacent to both ends of the remaining conduc-
tors or through the conductors. Drill the hole slightly larger than the wire diam-
eter to be used. (See Figure 2.)
11. Position the wire on the opposite side from the repair and insert the stripped
ends into the drilled holes.
12. Bend the stripped wire over the prepared conductors in line with the conduc-
tors. The wire should overlap the existing conductor a minimum of 2 times the
conductor width. (See Figure 3.)
NOTE
If the configuration permits, the overlap solder joint connection should be a
minimum of 3.00 mm from the related termination. This gap will minimize the
possibility of simultaneous reflow during soldering operations.
13. Apply a small amount of liquid flux to the overlap joint.
14 Lap solder the wire to the conductors on the printed wiring board surface. Make
sure the wire is properly aligned. (See Figure 4.)
15. Form the wire on the opposite side to match the shape of the missing conduc-
tor.
16. Clean the area.
NOTE
It may be necessary to encapsulate the solder joint connection if electrical spac-
ing is reduced.
17. If desired bond the wire to the printed wiring board surface with adhesive, epoxy
or Tape Dots.
CAUTION
Some components may be sensitive to high temperature.
18. Cure the epoxy per Procedure 2.7 Epoxy Mixing and Handling.
19. After the epoxy has cured clean the area.
Table 1 Solid Wire Equivalents
Conductor Width 2 oz. Copper Equivalent Solid Wire Diameter
0.25 mm #34, 0.15 mm
0.38 mm #32, 0.20 mm
0.50 mm #31, 0.23 mm
0.78 mm #29, 0.28 mm
2.08 mm #26, 0.46 mm
3.18 mm #23, 0.58 mm
When using solid wire to repair a conductor, there should be no reduction in the
cross sectional area.
IPC-7721
Number: 4.2.5
Revision:
Date: 2/98
Subject: Conductor Repair, Through Board Wire Method
Page2of4
EVALUATION
1. Visual examination for alignment and overlap of wire.
2. Electrical tests as applicable.
IPC-7721
Number: 4.2.5
Revision:
Date: 2/98
Subject: Conductor Repair, Through Board Wire Method
Page3of4
NOTES
IPC-7721
Number: 4.2.5
Revision:
Date: 2/98
Subject: Conductor Repair, Through Board Wire Method
Page4of4