A heat exchanger comprising: a plurality of first fluid passages, the plurality of first fluid passages defined by: a pair of opposing first fluid passage walls each having a first wall thickness; and a plurality of first fluid diverters disposed between the first fluid passage walls; wherein each of the plurality of first fluid passages extends in a first direction and receives the first fluid in the first direction; and a plurality of second fluid passages, the plurality of second fluid passages defined by: a pair of opposing second fluid passage walls; and a plurality of second fluid diverters disposed between the second fluid passage walls; wherein each of the plurality of second fluid diverters comprises a body portion and a leading edge portion; and wherein each of the plurality of second fluid passages extends in a second direction perpendicular to the first direction and receives the second fluid in the second direction; wherein the first fluid passage walls of at least one of the plurality of first fluid passages form a first fluid passage leading edge that extends upstream of the leading edge portions of the second fluid diverters; and wherein the first fluid leading edge has a leading edge thickness greater than the first wall thickness; characterized in that the body portion of the second fluid diverter has a first thickness, and the leading edge portion of the second fluid diverter has a second thickness; wherein the second thickness is greater than the first thickness. a plurality of first fluid passages, the plurality of first fluid passages defined by: a pair of opposing first fluid passage walls each having a first wall thickness; and a plurality of first fluid diverters disposed between the first fluid passage walls; wherein each of the plurality of first fluid passages extends in a first direction and receives the first fluid in the first direction; and a plurality of second fluid passages, the plurality of second fluid passages defined by: a pair of opposing second fluid passage walls; and a plurality of second fluid diverters disposed between the second fluid passage walls; wherein each of the plurality of second fluid diverters comprises a body portion and a leading edge portion; and wherein each of the plurality of second fluid passages extends in a second direction perpendicular to the first direction and receives the second fluid in the second direction; wherein the first fluid passage walls of at least one of the plurality of first fluid passages form a first fluid passage leading edge that extends upstream of the leading edge portions of the second fluid diverters; and a pair of opposing first fluid passage walls each having a first wall thickness; and a plurality of first fluid diverters disposed between the first fluid passage walls; wherein each of the plurality of first fluid passages extends in a first direction and receives the first fluid in the first direction; and a plurality of second fluid passages, the plurality of second fluid passages defined by: a pair of opposing second fluid passage walls; and a plurality of second fluid diverters disposed between the second fluid passage walls; wherein each of the plurality of second fluid diverters comprises a body portion and a leading edge portion; and wherein each of the plurality of second fluid passages extends in a second direction perpendicular to the first direction and receives the second fluid in the second direction; wherein the first fluid passage walls of at least one of the plurality of first fluid passages form a first fluid passage leading edge that extends upstream of the leading edge portions of the second fluid diverters; and a pair of opposing second fluid passage walls; and a plurality of second fluid diverters disposed between the second fluid passage walls; wherein each of the plurality of second fluid diverters comprises a body portion and a leading edge portion; and wherein each of the plurality of second fluid passages extends in a second direction perpendicular to the first direction and receives the second fluid in the second direction; wherein the first fluid passage walls of at least one of the plurality of first fluid passages form a first fluid passage leading edge that extends upstream of the leading edge portions of the second fluid diverters; and wherein the first fluid leading edge has a leading edge thickness greater than the first wall thickness; characterized in that the body portion of the second fluid diverter has a first thickness, and the leading edge portion of the second fluid diverter has a second thickness; wherein the second thickness is greater than the first thickness.