Abstract: An electronic assembly is provided. An electronic substrate of the assembly has a plurality of conductive lines to transmit signals, and a cooling opening therethrough. The cooling opening has an inlet to allow fluid into the electronic substrate, a section in the electronic substrate through which the fluid flows from the inlet, and an outlet from which the fluid flows from the section out of the electronic substrate. A semiconductor die of the assembly is mounted to the electronic substrate. The die has an electronic circuit connected to the metal lines so that signals are transmitted between the electronic circuit and the metal lines, operation of the electronic circuit causing heating of the die, heat being transferred from the die to the electronic substrate from where heat is transferred to the fluid flowing through the section.