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3.1 Delamination/Blister Repair, Injection Method Print   Next
Outline
This method is used to repair mechanical or thermal blisters or delaminations in circuit board laminated base materials. The blister is sealed by injecting a low viscosity epoxy into the blister/delamination void.

Caution
This method can only be used when the laminate base material has separated sufficiently to allow the epoxy to flow throughout the void area.
Minimum Skill Level - Advanced
Recommended for technicians with soldering and component rework skills and exposure to most repair/rework procedures, but lacking extensive experience.
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 3.1 Delamination/Blister Repair, Injection 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.
CircuitMedic Part
Circuit Bond Packs
Clear, superior strength epoxy in two-compartment plastic packages
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.
CircuitMedic Part
Mixing Picks
Unique mixing sticks have a paddle shape on one and sharp pick on the opposite end.
Oven
Oven
General purpose oven for drying, baking and curing epoxies.
CircuitMedic Part
Syringes
Polypropylene syringe barrels with stainless steel dispensing tips.
Wipes
Wipes
Nonabrasive, low-linting wipes for cleanup.
Images and Figures
3.1 Delamination/Blister Repair, Injection Method
Figure 1: Drill into the delamination blister using a ball mill and a Micro-Drill.
3.1 Delamination/Blister Repair, Injection Method
Figure 1: Drill into the delamination blister using a ball mill and a Micro-Drill.
3.1 Delamination/Blister Repair, Injection Method
Figure 2: Inject epoxy into the delamination blister.
3.1 Delamination/Blister Repair, Injection Method
Figure 3: Completed repair.
3.1 Delamination/Blister Repair, Injection Method
Figure 4: Micro-Drill System.
Procedure
  1. Clean the area.

  2. Drill into delamination blister with the Micro-Drill and ball mill. Drill in an area clear of circuitry or components. Drill at least two holes opposite each other around the perimeter of the delamination. (See Figure 1) Brush away all loose material.

    Caution
    Be careful not to drill too deep exposing internal circuits or planes.

    Caution

    Abrasion operations can generate electrostatic charges. 

  3. Bake the circuit board to remove any entrapped moisture. Do not allow the circuit board to cool prior to injecting the epoxy.

    Caution
    Some components may be sensitive to high temperature.  

  4. Mix the epoxy. See manufacturers instructions on how to mix epoxy without bubbles.

    Caution
    Exercise care to prevent bubbles in the epoxy mixture.  

  5. Pour the epoxy into the epoxy cartridge.

  6. Inject the epoxy into one of the holes in the delamination. (See Figure 2) The heat retained in the circuit board will improve the flow characteristics of the epoxy and will draw the epoxy into the void area filling it completely.

  7. If the void does not fill completely, the following procedures may be used:
    1. Apply light local pressure on the board surface starting at the fill hole, slowly proceeding to the vent hole.
    2. Apply vacuum to the vent hole to draw the epoxy through the void.

  8. Cure the epoxy per Procedure 2.7 Epoxy Mixing and Handling. Scrape away any excess epoxy using a knife or scraper.

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

Evaluation 

  1. Visual examination for texture and color match.

  2. Electrical tests to conductors around the repaired area as applicable.

Procedure for reference only.
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