Various electrode plates are used in infrared module packaging, and thermal damage to their metal electrodes must be avoided during laser processing. Based on the thermal conduction analysis of thin disk samples, a concise and clear analytical expression for the steady-state temperature distribution on the sample during laser processing is obtained under reasonable assumptions. Based on this, combined with the thermal parameters of the commonly used substrate materials and electrode materials of the electrode plate, the thermal damage distance of the sapphire electrode plate with the gold electrode in the steady state is obtained to be 3.3 mm, and the average laser processing power required for samples of different thicknesses is calculated. This method is suitable for the setting of relevant parameters and the estimation of the size of the thermal damage area in the laser processing of electrode plates or chips based on different substrates and electrode materials, avoiding complex finite element simulations, and can guide the design and matching of electrode plates and the setting of laser processing parameters.