Cooling of substrate using interposer channels

A structure, comprising:

• a substrate comprising N continuous substrate channels on a first side of the substrate, said substrate having a heat source therein, said N being at least 2;
• and
• an interposer comprising N continuous interposer channels, said N interposer channels being coupled to the N substrate channels so as to form M continuous loops such that 1≦M≦N, each loop of the M loops independently consisting of K substrate channels of the N substrate channels and K interposer channels of the N interposer channels in an alternating sequence of substrate channels and interposer channels, for each loop of the M loops said K is at least 1 and is subject to an upper limit consistent with a constraint of having the M loops collectively consist of the N interposer channels and the N substrate channels, each loop of the M loops independently being open ended or closed, said first side of the substrate being connected to the interposer, said interposer adapted to be thermally coupled to a heat sink such that the interposer is interposed between the substrate and the heat sink.