IPC 7711A - 第277页
OUTLINE This method is used to replace a damaged edge contact with a new edge contact. The new edge contact is bonded to the printed wiring board surface using liquid epoxy. CAUTION It is essential that the board surface…
NOTES
IPC-7721A
Number: 4.5.2
Revision:
Date: 2/98
Subject: Land Repair, Film Adhesive Method
Page4of4
Copyright Association Connecting Electronics Industries
Provided by IHS under license with IPC
Not for Resale
No reproduction or networking permitted without license from IHS
--``,``,-`-`,,`,,`,`,,`---
OUTLINE
This method is used to replace a damaged edge contact with a new edge contact.
The new edge contact is bonded to the printed wiring board surface using liquid
epoxy.
CAUTION
It is essential that the board surface be smooth and flat. If the base material is dam-
aged see appropriate procedure.
NOTE
This method uses commercially available replacement edge contacts. The edge
contacts are fabricated from copper foil. They are available in hundreds of sizes and
shapes and are generally supplied either plain copper, solder plated or nickel and
gold plated. If a special size or shape is needed they can be custom fabricated.
REFERENCES
2.1 Handling Electronic Assemblies
2.2 Cleaning
2.5 Baking And Preheating
2.6 Epoxy Mixing and Handling
TOOLS & MATERIALS
Cleaner
Epoxy
File, Finish Grade
Heat Lamp
Polyimide Tape
Knife
Liquid Flux
Microscope
Oven
Replacement Edge Contacts
Scraper
Solder
Soldering Iron
Tweezers
Wipes
PROCEDURE
1. Clean the area.
2. Remove the defective edge contact and a short length of the connecting con-
ductor. Heat from a soldering iron will allow the old contact to be removed more
easily.
3. Use the knife and scrape off any epoxy residue, contamination or burned mate-
rial from the board surface.
CAUTION
Abrasion operations can generate electrostatic charges.
Figure 1 Remove the defective edge
contact and solder resist.
Figure 2 Select a replacement contact
that matches.
Figure 3 Cut out the new edge
contact.
Figure 4 Place the new edge contact
in place using tape.
7721A
Repair and
Modification of
Printed Boards and
Electronic Assemblies
Revision:
Date: 2/98
Edge Contact Repair,
Epoxy Method
Number: 4.6.1
Product Class: R, F, W, C
Skill Level: Advanced
Level of Conformance: Medium
Material in this manual was voluntarily established by Technical Committees of IPC. This material is advisory only and its use
or adaptation is entirely voluntary. IPC disclaims all liability of any kind as to the use, application, or adaptation of this material.
Users are also wholly responsible for protecting themselves against all claims or liabilities for patent infringement. Equipment
referenced is for the convenience of the user and does not imply endorsement by IPC.
Page1of4
Copyright Association Connecting Electronics Industries
Provided by IHS under license with IPC
Not for Resale
No reproduction or networking permitted without license from IHS
--``,``,-`-`,,`,,`,`,,`---
4. Scrape off any solder resist or coating from the connecting conductor. (See Fig-
ure 1.)
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 conductor 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.)
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 conductor width. Leave the new edge contact extra long. The excess mate-
rial will be trimmed after curing. (See Figure 3.)
NOTE
The new replacement edge contact 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.
11. Place a piece of tape over the top surface of the new edge contact. Position the
new edge contact on the printed wiring board surface using the tape to aid in
alignment. (See Figure 4.)
NOTE
Allow the edge contact to overhang the edge of the printed wiring board. Leave
the tape in place during the bonding cycle.
12. Cure the epoxy per the manufacturer’s instructions.
CAUTION
Some components may be sensitive to high temperature.
13. After the epoxy has cured, remove the 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 conductor apply a small amount of
liquid flux to the lap solder joint connection area and solder the conductor from
the new edge contact to the conductor on the printed wiring board surface. Use
minimal flux and solder to ensure a reliable connection. 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 from the related termination. This gap will minimize the
possibility of simultaneous reflow during soldering operations.
15. Remove the tape and clean the area.
Figure 5 File overhanging piece of
new edge contact.
Figure 6 Completed repair.
IPC-7721A
Number: 4.6.1
Revision:
Date: 2/98
Subject: Edge Contact Repair, Epoxy Method
Page2of4
Copyright Association Connecting Electronics Industries
Provided by IHS under license with IPC
Not for Resale
No reproduction or networking permitted without license from IHS
--``,``,-`-`,,`,,`,`,,`---