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3.5.2 Base Material Repair, Area Transplant Method Print   Next
Outline
This procedure is used to repair mechanical or thermal damage to circuit board base material. This method is used when extended areas of base material must be completely replaced. This method may be used on single sided, double sided or multilayer circuit boards or assemblies.

Caution
Surface circuits may need to be replaced in the damaged area. Be sure that the appropriate circuit diagrams, or photographs reflecting the original circuits are available so that they may be replaced after repairing the base board material. Damage to internal circuits or planes may have to be restored using surface wires.
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
3.5.2 Base Material Repair, Area Transplant Method
Tools and Materials
CircuitMedic Part
Alcohol Swab
Self-saturating Isopropyl alcohol swab. Squeeze handle to release alcohol.
CircuitMedic Part
Ball Mills, Abrasives, Cutting Tools
Ball mills, abrasives and cutting tools for working on circuit boards.
Cleaner
Cleaner
General purpose cleaner for removing contamination.
CircuitMedic Part
Cleaning Brushes
Disposable brushes for use with solvents for cleaning and application of coatings.
Color Agent
Color Agents
Use to tint the color of epoxy used for solder mask repair or circuit base board repair.
End Mills
End Mills
Designed for end cutting and hole boring.
CircuitMedic Part
Circuit Bond Packs
Clear, superior strength epoxy in two-compartment plastic packages
CircuitMedic Part
File
High carbon steel needle file perfect for all kinds of detail work.
CircuitMedic Part
High Temp Tape Discs
High temperature polyimide tape discs, .50" diameter.
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.
CircuitMedic Part
Scraper
Hardened stainless steel tip for scraping solder mask and removing defects.
Wipes
Wipes
Nonabrasive, low-linting wipes for cleanup.
Images and Figures
3.5.2 Base Material Repair, Area Transplant Method
Damaged Base Material
3.5.2 Base Material Repair, Area Transplant Method
Figure 1: Mill away the damaged base material using the Micro-Drill System and ball mill.
3.5.2 Base Material Repair, Area Transplant Method
Figure 2: Bevel edge using the Micro-Drill System or file.
3.5.2 Base Material Repair, Area Transplant Method
Figure 3: Mill a step into the edge of the circuit board.
3.5.2 Base Material Repair, Area Transplant Method
Figure 4: Mill a step onto the edge of the replacement base material.
3.5.2 Base Material Repair, Area Transplant Method
Figure 5: Bond replacement piece in place.
3.5.2 Base Material Repair, Area Transplant Method
Figure 6: Completed repair.
3.5.2 Base Material Repair, Area Transplant Method
Figure 7: Micro-Drill System.
Procedure
  1. Clean the area

  2. Mill away the damaged board material using the Micro-Drill System and ball mill. Remove all evidence of the damaged material. No fibers of laminate material should be exposed. At the surface file the edges to ensure that the opening is rectangular or uniform in shape. (See Figure 1)

    Caution
    Abrasion operations can generate electrostatic charges. 

  3. Clean the area.

  4. Bevel the edge using the Micro-Drill System and ball mill or using a file. (See Figure 2)

    Or

    Install an end mill into the chuck of a Precision Drill System. Set the speed to maximum and machine a step or lap joint in the edge of the circuit board where the new base material will be installed. The depth and width of the step should be approximately 1/2 of the circuit board thickness. (See Figure 3)

    Caution
    Exercise care to avoid damage to any internal conductors. If any internal conductors are damaged, surface wires may be required. 

  5. Cut or machine a piece of replacement base board material that is the same thickness and type as the piece removed. The replacement piece must be precisely the same size and shape of the opening including the step joint.

  6. Install an end mill into the chuck of a Precision Drill Press. Machine a step onto the entire mating edge of the replacement base material. The dimensions of the step should match the size of the step in the circuit board milled groove. (See Figure 4)

  7. Where required apply High Temperature Tape to protect exposed parts of circuit board bordering the prepared area.

  8. Check the fit to be sure the new base material properly mates with the step in the circuit board.

  9. Mix the epoxy.

  10. Coat both the tongue and groove surfaces with epoxy and fit together. (See Figure 5) Remove excess epoxy.

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

  12. After the epoxy has cured remove the High Temperature Tape.

  13. If needed scrape off any excess epoxy using a knife or scraper.

    Note
    If needed, apply additional thin coating to seal any scraped areas. 

  14. Clean the area.

  15. Complete by drilling holes, slots, etc. or adding circuitry as required.

Procedure for reference only.
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