The formation of electronic assemblies including a heat spreader coupled to a die through a thermal interface material formed from an indium preform, is described. One embodiment relates to a method including providing a preform comprising indium, the preform including an indium oxide layer thereon. The method also includes exposing the preform to fluorine so that part of the indium oxide layer is transformed into an indium oxy-fluoride. The method may also include, after the exposing the preform to fluorine so that part of the indium oxide layer is transformed into an indium oxy-fluoride, positioning the preform between a die and a heat sink, and applying pressure to and heating the preform positioned between the die and the heat sink so that reflow occurs and a bond is formed between the die and the heat sink.