Epoxy is a permanent adhesive. When properly chosen for your application and substrates, and properly cured, it will form a strong, permanent bond. At times though, you may find that you need to recover bonded parts or clean parts to remove excess cured epoxy. So what do you do if you need to break that bond? Essentially you need to create a bond failure by getting the adhesive to fail. If you need to get the substrates apart, it will probably take some work using softening and separation methods. Which removal method you choose will depend on your substrate and what it can withstand as well as the epoxy. For parts that can either withstand heat, temperature cycling or water/chemical baths, we normally recommend the following to try.
NOTE: Before moving forward with the removal process, please remember your PPE (protective personal equipment) – wear goggles, gloves and a mask.
Heating the epoxy and the part can help break the bond. Heating the epoxy beyond its Tg (softening point) and/or cure temperature, can soften the epoxy. You can try this by using a heat gun or a soldering iron on the epoxy bond line, heating only small sections of the bond line at a time so it stays warm enough to soften. Heating the part can also help heat the epoxy keeping everything warm. You can try using a hot plate here. Once heated, you can start scraping the epoxy away with a plastic scraper (not metal to avoid damage to parts). You may need to re-heat the same area multiple times to penetrate the layers of epoxy.
If you can heat the parts to 300°C, the bond will fail, or if you can heat the parts to 400°C, the epoxy will turn to ash, leaving some residue on the substrates you will need to clean up using water/chemical baths.
Temperature Cycling can be done to work the bond line and force a delamination. For example, epoxy has a much bigger CTE than metal or ceramic and the bond line will be worked by the temperature cycling. This method can force the bond to fail at one of the substrate interfaces. At temperatures above the Tg, the epoxy will be a little softer for prying purposes and at colder or freezing temperatures, this shock will also work the bond line. You will still have to do some clean-up of the residue with a chemical.
Hot Water Soak
Placing the part in hot (boiling if possible) water and keeping hot for a period of hours is a successful and non-aggressive method of removal. Prying may be needed, but the substrates may just fall apart.
In situations, submerging the part in specific solvents/chemicals has done the job. Soaking will expand the epoxy making it softer and easier to remove. Starting with acetone first is a good choice, however acetone may not penetrate down into the layers, so you may need to soak more than once or try a more aggressive chemical. If you choose to use a more aggressive chemical, please test on the substrates you are working with to understand if potential damage to the part will occur. In order of chemical aggressiveness, you can try soaking the part for hours or overnight in:
- Acetone (most common solvent)
- Warm sulfuric acid
- Chlorinated solvents like methylene chloride
Prying may be needed on the softened epoxy. Using dental tools or little hand drill bits can help with clean up.
You may find that you need to try multiple methods to achieve success. Please keep in mind that each method will take time and patience. Patience is the capacity to accept or tolerate delay, trouble, or suffering without getting angry or upset. Good luck!
FOC EPOXY RESOURCES:
FOC Epoxy Tips: Click Here
- The Conundrum of Epoxy Temperature Storage
- Adding color, pigment to UV curable coatings
- Does epoxy cause core cracking? Tips to identify and prevent this phenomenon
- The Glass Transition in Epoxies
- Epoxy Bi-Pack News – and Usage Tips for Best Results
- Helpful Epoxy Tips (and a Few Tricks)
- Bond Line Thickness & More: Answers to Common Epoxy Questions
- Ideas to Adjust Your Epoxy Process: Recommendations to Reduce Waste (and Save Money) in Your Fiber Optic Cable Assembly Process
- Polymer Expert Blog: Defeating Bubbles . . . Part II
- Bonding Optical Fiber to the Ceramic Ferrule SERIES:
- Crystallization Content:
Additional resources from the FOC team include:
- Glossary, Acronyms, Military Specifications for Connectors: http://bit.ly/2a2EFn8
- Q&A Resource: email technical questions to AskFOC@focenter.com
- Bookmark the ÅngströmBond Solutions Center: https://focenter.com/angstrombond/
ÅngströmBond Solutions Center for additional epoxy expertise through:
- technical content, best practices, weekly tips
- our dedicated adhesives expert to help meet Individual customer needs
- specialty stock materials or high-tech custom epoxies in custom package sizes
- FOC developed ÅngströmBond, the only specialty adhesive line developed exclusively for Fiber Optics
Do you have a specific issue regarding epoxies and adhesives?
We’re here to help! Send us your question, and we’ll do our best to provide guidance. FOC is committed to helping you manufacture the best fiber optic cable assemblies in the world. FOC is a resource for questions on this and all technical subjects. AskFOC can be found at: https://focenter.com/askfoc/ where our technical experts answer your questions.
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