Thermal runaway evaluation using DSC1, VSP2, and kinetics models on Cu etchant and its waste in high-tech etching process

Abstract

Cu etchant solutions have been widely used in etching processes because of their high etching efficiency and low cost for manufacturing electric products. Hydrogen peroxide (H2O2), a major components of Cu etchants, is known for its instability and reactivity under thermal induction, metal-ion catalysis, or pyrolysis; thus, Cu etchants have a higher risk of thermal explosion than other etchant solutions do. In this study, the exothermic reaction of the Cu etchant was initiated at approximately 70 °C, and the exothermic enthalpy (ΔH) of the first peak was measured to be approximately 274.4 J g−1 using differential scanning calorimetry 1 (DSC1). The American Society for Testing and Materials (ASTM)—Ozawa/Kissinger method, and Advanced Kinetics and Technology Solutions (AKTS)—Friedman simulation, were used to calculate the reaction kinetics. Thermal runaway and gas evolution were evaluated through vent sizing package 2 (VSP2). The pressure of the Cu etchant surged from atmospheric pressure to a maximum pressure of 225.075 psig, with a pressure increase of 168.684 psig min−1 in the VSP 2 adiabatic test. Finally, to improve the safety operation during the etching process, thermokinetic analysis was used to identify appropriate kinetic parameters for the thermal decomposition of the Cu etchant.