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3.3.2 Hole Repair, Transplant
Outline
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.
Minimum Skill Level - Expert
Recommended for technicians with advanced soldering and component rework skills and extensive experience in most repair/rework procedures.
Conformance Level - High
This procedure most closely duplicates the physical characteristics of the original, and most probably complies with all the functional, environmental and serviceability factors.
Acceptability References
IPC-A-600 2.0 Externally Observable Characteristics
IPC-A-610 10.0 Laminate Conditions
Procedure References
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 and Materials
CircuitMedic Part
Base Board Repair Kit
Most types of damage to base board can be repaired with this versatile repair kit.
Cleaner
Cleaner
General purpose cleaner for removing contamination.
End Mills
End Mills
Designed for end cutting and hole boring.
CircuitMedic Part
Epoxy Kit
High temperature epoxy for masking and structural repairs to circuit boards.
CircuitMedic Part
High Temp Tape Discs, .50" Diameter
High temperature polyimide tape discs.
CircuitMedic Part
Knife with #16 Blades
A must-have tool for precise cutting, scraping and trimming.
Microscope
Microscope
It is a challenge to undertake precision repair without a good microscope.
CircuitMedic Part
Micro Drill System
Versatile power tool for milling, drilling, grinding, cutting and sanding circuit boards.
Oven
Oven
General purpose oven for drying, baking and curing epoxies.
Precision Drill
Precision Drill
Precision drill press for accuracy and controlled depth drilling.
Wipes
Wipes
Nonabrasive, low-linting wipes for cleanup.
Images and Figures
3.3.2  Hole Repair, Transplant Method
Damaged Hole, Non Plated
3.3.2  Hole Repair, Transplant Method
Figure 1: New hole is milled to encompass entire damaged area.
3.3.2  Hole Repair, Transplant Method
Figure 2: Place replacement dowel in position and bond with epoxy.
3.3.2  Hole Repair, Transplant Method
Figure 3: Cut off excess material and redrill holes as required.
3.3.2  Hole Repair, Transplant Method
Figure 4: Micro-Drill System.
Procedure 
  1. 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. 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. 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.

This procedure is for reference only. Refer to the Procedure References listed above, or contact Circuit Technology Center for appropriate industry approved references.
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CircuitMedic
22 Parkridge Road, Haverhill, MA 01835 USA
Phone: 978-373-1600 - Fax: 978-372-5700
Division of Circuit Technology Center, Inc.
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