The Invention pertains to a heat sink comprising a substantially planar solid slab, provided with a plurality of fluid flow channels, said plurality of fluid flow channels being formed so as to channel a coolant from an inlet to an outlet of said slab, wherein said plurality of channels includes at least two main channels interconnected by at least a plurality of bridging channels that do not branch out further between their respective points of attachment to said main channels, wherein said bridging channels have a cross section that locally increases in the direction of flow, and wherein said bridging channels have a cross section that locally decreases in the direction of flow, downstream of said local increase in cross section. The invention also pertains to a method for producing a heat sink.