Reworking, Removing and “Decapsulating” Cured Epoxies WhAt > Removing Cured Epoxy a Major Advantage of Using an Epoxy Is Easily

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www.epotek.com Tech Tip 8 Reworking, Removing and “Decapsulating” Cured Epoxies What > Removing Cured Epoxy A major advantage of using an epoxy is easily. The tip of a soldering iron can be Why > There are sev- that it provides a very strong, permanent used as the heating mechanism and can eral techniques which have bond in adhesive applications. This perma- be applied directly on the epoxy or at the shown to be effective tools nence can also act as a limitation when bond line. When the adhesive becomes in removing cured epoxy needing to rework, remove or “decapsu- soft and “gummy”, de-bonding can occur. from substrates. late” the cured epoxy. This document lists Heating of the substrate using a hot plate several techniques which have shown to is another common technique, as well as be effective tools in removing cured epoxy using a conventional box oven. from substrates. 5. Degradation temperature of the epoxy. 1. Chlorinated solvent is the most aggres- Most epoxies will decompose and turn to sive way to attack cured epoxy. Methylene carbon ash at temperatures of 400°C and chloride (dichloromethane) has shown the above. By heating the unit above the deg- most success but does require the material radation temperature (found on the data to be soaked for several hours. Stripping sheet), the epoxy adhesive simply burns Agent MS-111 (which contains approxi- away. mately 85% methylene chloride) from the Miller- Stephenson Chemical Co. in 6. Boiling water. Epoxies, when exposed Danbury, CT is a product that works very to boiling water for an hour or so, will well. Dynaloy LLC also has several epoxy lift away from any surfaces in most cases. solvents and removers based on which type Some prying action may be needed and of epoxy hardener is used in a product. this technique can vary widely depending on epoxy and bonding surfaces. 2. A warm solution of sulfuric acid will dissolve the cured epoxy. This, like the 7. Thermal shock. Large differences in chlorinated solvents, also requires a good thermal expansion rates between a sub- soaking. An effective technique that some strate, adhesive or component can stress customers have used is repeatedly dropping the epoxy and create joint separation as the acid on the top surface of the epoxy to well as bond line lift. Thus, by impos- facilitate the removal. ing severe thermal fatigue on the adhesive joint, de-bonding can be accomplished 3. Other chemicals which have shown to simply by the thermal-mechanical differ- be effective: toluene, NMP (n-methly- ences of adhesive and substrate. pyrollidone) and MEK (methyl-ethyl- ketone). Several of the techniques listed are destruc- tive in nature and can be suicidal in terms 4. Combination of heat and pressure. of re-usable parts for manufacturing. This Since epoxies are thermosetting resins, they document makes no attempt to suggest have a softening point called the glass tran- how manufactured parts can be saved sition temperature (Tg). Heating above or reclaimed. Its intention is to provide the Tg will soften the material slightly and means of solving erroneously placed epoxy or components, and failure analysis. Innovative Epoxy Adhesive Solutions for Over 40 Years™ allow the epoxy to be pried away more

DISCLAIMER: Data presented is provided only as a guide in selecting an adhesive. Properties listed are typical, average values, based on tests believed to be accurate. It is recommended the user perform a thorough evaluation for any application based on their specific requirements. Epoxy Technology makes no warranties (expressed or implied) and assumes no responsibility in connection with the use or inability to use these products. Epoxy Technology Inc. • 14 Fortune Drive • Billerica, MA 01821 phone 978-667-3805 fax 978-663-9782 Toll Free 800-227-2201 [email protected]