Solid-state overvoltage firing switch

An assembly can include solid-state overvoltage firing switch operable to control an explosive device. The solid-state overvoltage firing switch can include a substrate layer. The solid-state overvoltage firing switch can also include a conductive anode and a conductive cathode positioned on the substrate layer. A gap can physically separate the conductive anode from the conductive cathode. The conductive anode can be operable to receive a voltage from a power source. The solid-state overvoltage firing switch can further include an insulator layer adjacent to the conductive anode and the conductive cathode. At least part of the insulator layer can fill the gap. The insulator layer can cover a first portion of the conductive anode and a second portion of the conductive cathode.