Embodiments relate to electronic assemblies and methods for forming electronic assemblies. One method includes providing a die and a copper heat spreader that are to be coupled to one another through a thermal interface material. A layer of tin is formed on the copper heat spreader. The heat spreader and the die are clamped together with the tin positioned between the heat spreader and the die. The assembly is heated so that the tin melts and forms at least one intermetallic compound with copper from the heat spreader. The heat spreader is then coupled to the die through the intermetallic compound.