Corrosion of Copper in Fluorochemical Liquid Coolants^★

In using fluorochemical liquid coolants for electronic devices, corrosion had been observed on component parts. Preliminary tests were performed at 100 C (212 F) by immersing the copper strips in a series of commercial fluorocarbons: C₅F₁₁NO, C₈F₁₆O, C₈F₁₈, C₇F₁₄, and C₆F₁₄. Oxygen dissolved in these coolants was found to be causing oxidation of copper to cuprous oxide. Extensive investigation on the corrosion kinetics of copper in one selected coolant, C₅F₁₁NO, was conducted by using the electrometric method. The effects of dissolved air and/or water on the corrosion behavior of copper were determined using aerated and de-aerated C₅F₁₁NO with and without the presence of water. Suspected contaminants including mold epoxy, glass laminated epoxy board, and neoprene rubber were introduced into the coolant. Their effect on the corrosion of copper was also examined.