Circuit Technology Center
 
No. 3.3.2
Hole Repair, Transplant Method

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.
 
ACCEPTABILITY REFERENCES
IPC-A-600  2.0 Externally Observable Characteristics
IPC-A-610 10.0 Laminate Conditions
   
PROCEDURE REFERENCE
CTC 7721 1.0 Foreword
CTC 7721 2.1 Handling Electronic Assemblies
CTC 7721 2.2 Cleaning
CTC 7721 2.5 Baking and Preheating
CTC 7721 2.7 Epoxy Mixing and Handling
IPC 7721 3.3.2 Hole Repair, Transplant Method

TOOLS & MATERIALS
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. 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 Figures 1 and 2).

    3. 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 3). Remove excess epoxy.


  8. Cure the epoxy per Procedure 2.7 Epoxy Mixing and Handling.

    9. 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 4).


  10. Complete the procedure by redrilling holes and adding circuitry as required. (See Figure 4).


    11. 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.

 

  
Solutions Across the Board TM

Product Class:  R/W
Skill Level:  Expert
Conformance Level:  High
Revision:  E
Revision Date:  Jul 7, 2000 
Repair Service Charge

  
Damaged Hole, Non Plated


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


Figure 2: Precision Drill System for accurate hole drilling and milling.


Figure 3: Place replacement dowel in position and bond with epoxy


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


Figure 5: Micro-Drill System.
Tricks of the Trade
 This is a challenging, but highly reliable rework/repair procedure. Should not to be attempted by rookies. Call for assistance with the dowel material. We recommend Pre-packaged Epoxy to bond the replacement dowel in place. Mix a Color Agent in with the Epoxy if needed. You'll need to drill out the hole accurately. We recommend a Precision Drill fitted with a carbide End Mill for the initial drilling.
 
 
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