A surge protective device (SPD) module includes a module housing, first and second module electrical terminals mounted on the module housing, an overvoltage clamping element electrically connected between the first and second module electrical terminals, and a thermal disconnector mechanism. The thermal disconnector mechanism is positioned in a ready configuration, wherein the overvoltage clamping element is electrically connected with the second module electrical terminal. The thermal disconnector mechanism is repositionable to electrically disconnect the overvoltage clamping element from the second module electrical terminal. The thermal disconnector mechanism includes: an electrode electrically connected to the overvoltage clamping element; a disconnect spring elastically deflected and electrically connected to the electrode in the ready configuration; a solder securing the disconnect spring in electrical connection with the electrode in the ready configuration; and a heat sink member thermally interposed between the electrode and the solder, the heat sink member having a thermal capacity. The solder is meltable in response to overheating of the overvoltage clamping element. The disconnect spring is configured to electrically disconnect the overvoltage clamping element from the second module electrical terminal when the solder is melted. The thermal capacity of the heat sink member buffers and dissipates heat from the overvoltage clamping element to prevent the solder from melting in response to at least some surge currents through the SPD module.