Is Hot Glue OK for Electronics?by John Papiewski
When used with care, the hot glue used by hobbyists and craftspeople is safe for electronic projects. The glue, a plastic resin which typically melts at temperatures ranging from 250 to 380 degrees Fahrenheit, is an electrical insulator, so it does not create stray conducting paths or short circuits. For best results, avoid using hot glue on thermally sensitive components or power devices that produce heat.
Hot glue is OK when used on rugged passive components such as resistors, coils and ceramic capacitors. Electrolytic capacitors, however, usually have a thin plastic wrapper that hot glue may melt and damage, so avoid applying the glue to these components. Metal mounting parts such as screws and brackets are usually safe for hot glue, although plastic parts may deform or melt from the glue's heat. Nonconducting parts of circuit boards consist of an epoxy resin; hot glue is safe with this material.
Power components, including large transistors, integrated circuits and diodes, have metal bodies designed to give off heat during operation. Although hot glue won't harm these components directly, it is inappropriate for these parts. When a transistor becomes hot, it will soften or melt any glue applied to it, causing the glue to weaken and break. Also, the glue is a thermal insulator; if a glue-covered transistor cannot radiate heat away from itself, it may overheat and fail.
Circuits which operate at frequencies exceeding 100 kHz are sensitive to changes in the capacitance of components and the circuit boards to which they are connected. Avoid applying hot glue to conducting parts of circuit boards, wires or component leads on high-frequency circuits, as it may increase the capacitance of sensitive circuit parts, leading to erratic performance. Hot glue used on other parts of high-frequency electronics is OK.