Circuit Board Repair and Rework Guide > 3.0 Base Board Procedures > 3.1 Delamination / Blister Repair, Injection Method

3.1 Delamination / Blister Repair, Injection Method

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

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-610	2.0	Externally Observable Characteristics
IPC-A-600	10.0	Laminate Conditions

Delamination

Procedure References
CTC	1.0	Foreword
CTC	2.1	Handling Electronic Assemblies
CTC	2.2.1	Cleaning, Local
CTC	2.2.2	Cleaning, Aqueous Batch Process
CTC	2.5	Baking and Preheating
CTC	2.7	Epoxy Mixing and Handling
IPC7721	3.1	Delamination/Blister Repair, Injection Method
Tools and Materials
Adhesive Dispenser Ball Mills Base Board Repair Kit Cleaner Epoxy Heat Lamp		Micro-Drill System Oven Scraper Vacuum Source, Optional Wipes

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

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.

Figure 2: Inject epoxy into the delamination blister.

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: Apply light local pressure on the board surface starting at the fill hole, slowly proceeding to the vent hole. 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.

Figure 3: Completed repair.

Evaluation

1.	Visual examination for texture and color match.

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

Figure 4: Micro-Drill System.

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