Patent ID: 7950149

Claim:
A method of making a microchannel heat exchanger core comprising the steps of: performing electrical discharge machining of a plurality of microchannels and fins on at least two panels using an electrode to provide machined panels, wherein the fins separate the microchannels by providing walls for the microchannels and wherein the microchannels have an aspect ratio of depth to width of at least about 10; etching the microchannels of the machined panels; arranging the machined panels one on top of the other; and joining the machined panels together by brazing, welding or gasketing; wherein the step of performing electrical discharge machining comprises: applying a first voltage to an electrode; moving the electrode downward into one side of the panel to a desired depth to form a microchannel; changing a voltage applied to the electrode to a second voltage after the desired depth is reached; moving the electrode sideways by a predetermined amount; and changing a voltage applied to the electrode to zero voltage as the electrode is moved upward out of the panel.