Printed Board Type: R/W
Skill Level: Expert
Conformance Level: High
Revision: E
Revision Date: Jul 7, 2000

OUTLINE

Damaged Hole, Non Plated

This method is used to repair severe damage to a hole or to modify the size, shape or location of an unsupported tooling or mounting hole. The hole may have component leads, wires, fasteners, pins, terminals or other hardware run through it. This repair method uses a dowel of matching board material and high strength epoxy to secure the dowel in place. After the new material is bonded in place a new hole can be drilled. This method can be used on single sided, double sided or multilayer circuit boards and assemblies.

CAUTION
Damaged inner-layer connections may require surface wire adds.
  ACCEPTABILITY REFERENCES

IPC-A-600 2.0	Externally Observable Characteristics
IPC-A-610 10.0	Laminate Conditions
PROCEDURE REFERENCE
1.0	Foreword
2.1	Handling Electronic Assemblies
2.2	Cleaning
2.5	Baking and Preheating
2.7	Epoxy Mixing and Handling
IPC7721 3.3.2	Hole Repair, Transplant Method

TOOLS & MATERIALS

Figure 1: New hole is milled to encompass entire damaged area.

Base Board Repair Kit
Base Material Rod
Cleaner
End Mills
Epoxy
Knife
Micro-Drill System
Microscope
Mixing Sticks
Oven
Precision Drill System
Razor Saw
Tape, Kapton
Wipes

PROCEDURE

1. Figure 2: Place replacement dowel in position and bond with epoxy.

   Clean the area.
   
   
2. Drill out the damaged or improperly sized hole using a carbide end mill or drill. Mill the hole using a precision drill press or milling machine for accuracy. The diameter of the cutting tool should be as small as possible yet still encompass the entire damaged area. (See Figure 1).

   
   NOTE
   Abrasion operations can generate electrostatic charges.  

3. Cut a piece of replacement base material rod. Base material rod is made from FR-4 dowel stock. Cut the length approximately 12.0 mm (0.50") longer than needed.
   
   

4. Figure 3: Cut off excess material and redrill holes as required.

   Clean the reworked area.
   
   
5. Use Kapton tape to protect exposed parts of the circuit board bordering the rework area.
   
   
6. Mix the epoxy.
   
   
7. Coat both the dowel and the hole with epoxy and fit together. Apply additional epoxy around perimeter of new material. (See Figure 2). Remove excess epoxy.
   
   
8. Cure the epoxy per Procedure 2.7 Epoxy Mixing and Handling.
   
   CAUTION
   Some components may be sensitive to high temperatures.
    

9. Figure 4: Micro-Drill System.

   Remove Kapton tape and cut off the excess material using the razor saw. Mill or file the dowel flush with the board surface. (See Figure 3).
   
   
10. Complete the procedure by redrilling holes and adding circuitry as required. (See Figure 3).
    
    

    NOTE
    Apply surface coating to match prior coating as required. 

11. Clean the reworked area.
    

EVALUATION

1. Visual and dimensional examination of the reworked area for conformance to drawings and specifications.