Circuit Technology Center

2.7 Epoxy Mixing and Handling

This procedure covers epoxy mixing and handling. The epoxy covered by this procedure has multiple uses, including solder mask repair, base board repair, circuitry over-coating, and delamination repair.

Note: For high strength or high-temperature applications two-part epoxies will generally have the best properties.

Minimum Skill Level - Intermediate
Recommended for technicians with skills in basic soldering and component rework, but may be inexperienced in general 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.

Kits and Systems
Base Board Repair Kit
Kit to repair base board and laminate damage on circuit boards.
Circuit Bond Kit
Includes packages of clear, low viscosity, superior strength epoxy for circuit board damage repair.
Repair Skills Practice Kit
Training kit to practice circuit board repair skills prior to testing for certification.
Tools and Materials
Cleaning Brushes
Disposable brushes for solvent cleaning and application of coatings.
Color Agents
Use to tint the color of epoxy used for solder mask repair or circuit base board repair.
Circuit Bond Epoxy
Clear, superior strength epoxy in two-compartment plastic packages.
Foam Swab, Small
Swabs for use with solvents and application of color agents and epoxies.
Additional Items and Supplies
General purpose cleaner for removing contamination.
General purpose oven for drying, baking and curing epoxies.
Nonabrasive, low-linting wipes for cleanup.
Circuit Bond Epoxy
Circuit Bond is a clear, low viscosity, superior strength epoxy precisely measured out into two-compartment plastic packages, so it's easy to use, and there's no measuring. For over a decade, this high-strength epoxy has been qualified and used by thousands of high-rel electronics manufacturers across the globe.
1. Circuit Bond has a working pot life of 30 minutes. It should not be mixed until ready to use.
2. To use Circuit Bond, remove the plastic clip separating the resin and hardener. Squeeze back and forth from one half of the package to the other to mix the contents.
3. Cut a corner off the package and squeeze all the contents into a Plastic Cup. Stir the contents to ensure it is thoroughly mixed.
4. Circuit Bond may contain bubbles from the mixing process. If needed, use a vacuum system to remove bubbles.
5. Color Agent can be mixed in with Circuit Bond to match surface colors if desired.
6. Apply using a Foam Swab, Micro Probe, or Mixing Stick as required.
7. Cure Circuit Bond for 24 hours at room temperature or 4 hours at 65°C (150°F).
Packaging2 gram pre-measured packages
Mix ratio4 parts resin to 1 part hardener
Mix Ratio by Weight (R/H)100/25
ColorClear, transparent
Pot life30 minutes
Cure cycle24 hours at room temp (25 °C) or 4 hours @ 65°C
Thixotropic Index1
Specific Gravity1.20
Percent Solids100%
Viscosity (after mixing)2000 cps
Operating temperature range-55°C to 135°C
Hardness88 Shore D
Lap Shear, Alum to Alum1100 psi
Glass Transition Temperature, Ultimate92°C
Coefficient of Expansion, cm/cm/°C6 E-05
Dielectric strength400 volts/mil
Dielectric Constant, 1KHz@25°C4
Shelf Life6 months minimum
Color Agents
Color Agent is a one-part, air-drying, semi-paste ink commonly used to print hard surfaces, including circuit board base materials. Color Agent can be used to tint the color of epoxy used for solder mask repair or circuit baseboard repair. To use, mix a small amount of color agent with 2 part epoxy as the epoxy is initially mixed. Add more color agents to increase the color intensity if needed.
Part No. Description
115-9102 115-9102 Color Agent, Yellow
115-9185 115-9185 Color Agent, Red
115-9293 115-9293 Color Agent, Blue
115-9348 115-9348 Color Agent, Green
115-9358 115-9358 Color Agent, Light Green
115-9376 115-9376 Color Agent, Medium Green
115-9424 115-9424 Color Agent, Dark Gray
115-9457 115-9457 Color Agent, Light Brown
115-9560 115-9560 Color Agent, Dark Green
115-9561 115-9561 Color Agent, Green
115-9995 115-9995 Color Agent, Black
115-9996 115-9996 Color Agent - White
Images and Figures
2.7 Epoxy Mixing and Handling
Figure 1: For prepackaged epoxy, remove divider clip and mix resin and hardener inside package.
2.7 Epoxy Mixing and Handling
Figure 2: Apply epoxy as needed. Foam swabs may be used to add texture for soldermask repair.
Epoxy Specifications
Epoxies used for circuit board repair and rework require specific properties. The Epoxy referenced in this procedure is a clear, low viscosity, superior strength two-part epoxy. It is available in two-compartment plastic packages, so no measuring is needed.

See the Related Products below for details about the Epoxy referenced in this procedure.

The area where the epoxy is to be applied should be prepared prior to mixing the epoxy. This preparation may include preheating the affected area to improve absorption of the applied epoxy. The entire circuit board may also be heated in an oven or with a heat lamp.

Caution: Some components may be sensitive to high temperatures.

Procedure - Prepackaged Two Part Epoxy
  1. Remove the clip separating the resin and hardener. Mix by squeezing both halves together with your fingers. Mix for at least one minute to ensure a complete mix of the resin and activator. (See Figure 1)
  2. Cut open one end of the epoxy tube and squeeze the contents into a mixing cup. Mix again with a mixing stick to ensure a thorough mixture of the resin and hardener.
    Note: For bubble-free epoxy, remove the clip separating the resin and hardener. Cut open one end of the Epoxy tube and squeeze the contents into a mixing cup. Slowly stir the mixture with the mixing stick. Be sure to stir the mixture for at least 2 minutes to ensure that all the resin and hardener have completely mixed.
  3. If needed, add a color agent to the mixed epoxy. Stir slowly to prevent bubbles.
  4. Apply or use as needed. (See Figure 2)
  5. Cure the epoxy for 24 hours at room temperature or 1 hour @ 165F (74C)
  1. Visual examination of epoxy for texture and color match.
  2. Testing of epoxy surface for complete cure.
  3. Electrical tests as applicable.
Procedure for reference only.