So, you opened up an electronic device, and there are some fancy components like 6-segment digital LCD screens taht you’d like to salvage for use in hobby projects. But alas, you see that your desired component is glued onto the circuit board! How do you get it off?
Some background knowledge is very useful in devising a strategy for removing pesky bonding materials. There are three main methods of removing bonding materials:
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Mechanical: These are strictly methods that involve cutting at the bond with a knife, rubbing at it with sandpaper, or going all out with a rotary cutter to really grind down that pesky bonding material!
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Thermal: Heat up the bonding material so that it melts or softens.
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Chemical: Use some sort of acids to dissolve your bonding chemical.
Typically, if you have no idea what you are working with, the easiest and safest method is to go with a combination of mechanical and thermal removal. Heat up the joint in hopes that doing so will soften the bonding material, as is the case with some types of epoxy. A hairdryer is the go-to DIY hobbyist tool to get started on this, but if you are better equipped, you may go with a heat gun or a heated knife instead. Anyways, once you’ve got your joint heated, cut away at the joint with a utility knife.
My understanding is that the chemical removal method is generally not recommended because it has a greater propensity to damage your electronic components, and in the case of epoxy, it’s really not effective at all.
Finally, have you been wondering about those calculator circuit boards? You open them up and look inside, and you can see that the CPU is covered with something that either looks like a piece of “leather” or is a drop of epoxy. What is this? This is “chip on board” mounting: the unpackaged silicon dye is mounted directly onto the circuit board, ahd epoxy is used to cover it to protect it from moisture, fingerprint grease, corrosive gases, or other environmental contaminants. It is ostensibly the go-to choice for cheap, mass-market electronics. This is also called “blob top” or “glop top.”
20190215/DuckDuckGo how to dissolve unglue components from circuit board
20190215/DuckDuckGo how to dissolve unglue lcd from circuit board
20190215/DuckDuckGo how to dissolve unglue lcd from circuit board calculator
20190215/DuckDuckGo remove glued components from circuit board
20190215/https://electronics.stackexchange.com/questions/9377/how-to-remove-glue-block-from-pcb
20190215/https://itstillworks.com/circuit-board-epoxy-removal-5799527.html
20190215/https://en.wikipedia.org/wiki/Chip_on_board
20190215/https://en.wikipedia.org/wiki/Electronic_packaging#Glop-top