When working with circuit boards, you’re likely to often encounter areas that are covered in heavy-duty epoxy. This is installed by the manufacturer to safely encase certain sensitive components, such as chips or resistors, that aren’t meant to be modified or handled easily. However, if you’re looking to make some modifications or fixes to a circuit board, you might just need to remove this epoxy to get to what’s under it. There are several methods you can attempt to accomplish this.
Heat
Depending on the type of epoxy used, you may find that heat can easily help remove it. Many forms of pure epoxy are designed to soften under extremely high direct heat. This means that you won’t be able to simply take a blow-dryer to the circuit board in order to get the epoxy off. Additionally, you need to be careful to not overheat the rest of the surrounding area on the circuit board, as you could run the risk of damaging exposed components. Instead, you need to find a heat gun. Heat guns are essentially extremely high-powered blow-dryers in a smaller package. They blast heat in a concentrated area, and the best heat guns have temperature settings that reach far above what you would need on epoxy. They can be found at most common hardware stores, and entry-level models are relatively affordable. Most epoxy can be softened with about 200 degrees Fahrenheit of heat, so there’s no need to get a gun that reaches far above that. Concentrate the heat directly onto the epoxy, taking care not to stray too far off it onto the rest of the circuit board. Use a small utility knife to periodically scrape at the epoxy as you heat it. Eventually it will start to soften, and you’ll be able to gently scrape it free little by little. This can be very slow going, as the epoxy used is often extremely durable and strong. Wipe excess epoxy off the knife onto a shop rag so it doesn’t re-dry or fall onto other areas of the circuit board. As you start to make progress, take care not to scrape too hard or too deep into the components hidden underneath.
Rotary Tool
If you’re confident in your ability to handle a cutting tool so close to sensitive components, or if the epoxy area in question is quite large, you may consider using a small router or Dremel-style rotary tool. In its dried form, the epoxy has the consistency and behavior of hard plastic. This makes it ideal for cutting and grinding away with a router. Unfortunately, on circuit boards, a standard large router is out of the question. Instead, you need a small hand-held rotary cutter with a small cutting bit attached. These are usually made for finishing small detailed areas on woodwork and the like, but because of their size and controllability they’re also ideal for removing epoxy in the small areas of a circuit board. Slowly grind away at the epoxy from the top down. Stop every once in a while to clear away any debris or remaining dust, and always keep a close eye out to make sure you don’t inadvertently grind into components underneath the epoxy. Because the router makes it so easy to accidentally cut through these components, it might be a good idea to only grind away the bulk of the epoxy from the top and then use heat to remove the rest with a small utility knife.
