bond pads 34 may also be bonded to the signal traces 36 using tape automated bonding tab techniques wherein the conductors are carried on a flexible dielectric film also the signal traces 36 may comprise a wide variety of conductors including without limitation copper gold and platinum further it should be understood that while the multi chip module 20 of fig2 is shown as having a single insulating layer 24 between the conductive layer 28 and the signal traces 36 the present invention is equally applicable to cob applications in which there are multiple superimposed layers such as insulating conductive or signal layers between a conductive layer to which the backside of a die is directly attached and the signal layer to which the front side of each die is bonded because the present invention directly attaches the backsides of dice to a conductive layer heat from the dice is advantageously conducted away from the dice through the conductive layer also as shown in fig2 a substrate bias voltage generator 38 can supply a substrate bias voltage v bb to the backsides not shown of the dice 22 through the conductive layer 28 as a result there is no need for on board substrate bias voltage generators not shown in the dice 22 and there is no need to supply the substrate.