A circuit board may include a pump and a channel. The channel may include a liquid metal and a coating. The liquid metal may be pumped through the channel by the pump and the coating reduces diffusion and chemical reaction between the liquid metal and at least portions of the channel. The liquid metal may carry thermal energy to act as a heat transfer mechanism between two or more locations on the substrate. The substrate may include electrical interconnects to allow electrical components to be populated onto the substrate to form an electronics assembly. The pump may be driven by electric current that is utilized by one or more electronic components on the circuit board.