Copper coil. For the small motor coil of electric drill screwdriver, it is common and applicable to use copper coil. Copper has excellent electrical and thermal conductivity, which can effectively transfer electric energy and dissipate heat, and keep the motor working stably. In addition, copper coils have good plasticity and corrosion resistance, are easy to process and use, and have long service life, so they are widely used in small motors of electric drills and screwdrivers.