Prime surface heat exchanger with contoured separator members

A method of manufacturing a heat exchanger for a first fluid and a second fluid, the method comprising:

• forming a plurality of separator members, the plurality of separator members respectively including a first surface and a second surface, the second surface opposite the first surface, the plurality of separator members respectively including an array of wave features, the wave features making the first surface and the second surface uneven and making the first surface inverse to the second surface;
• interconnecting the plurality of separator members in an alternating arrangement with the first surfaces of adjacent separator members facing each other and attached at the respective wave features, and with the second surfaces of adjacent separator members facing each other and attached at the respective wave features;
• defining a plurality of first flow passages between respective first surfaces of the separator members, the first flow passages configured to direct flow of the first fluid therethrough;
• and
• defining a plurality of second flow passages between respective second surfaces of the separator member, the second flow passages configured to direct flow of the second fluid therethrough, the second fluid and the first fluid being configured to exchange heat through the separator members.