Circuit Board Rework and Repair Guide

3.1 Delamination/Blister Repair, Injection Method

Printed Board Type: R
Skill Level: Advanced
Conformance Level: High
Revision: D
Revision Date: Jul 7, 2000

Delamination

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.

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 3.1	Delamination/Blister Repair, Injection Method

Figure 1: Drill into the delamination blister using a ball mill and a Micro-Drill.

TOOLS & MATERIALS
Adhesive Dispenser
Ball Mills
Base Board Repair Kit
Cleaner
Epoxy
Heat Lamp
Micro-Drill System
Oven
Scraper
Vacuum Source, Optional
Wipes

PROCEDURE

1. Clean the area.
   
   

2. Figure 2: Inject epoxy into the delamination blister.

   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. Figure 3: Completed repair.

   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. Figure 4: Micro-Drill System.

   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.
   
   
9. 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.