Abstract: A system (100), which has an electrically insulating substrate (101) with a thickness, a first and a second surface. Electrically conductive paths (110) extend through the insulating body from the first to the second surface and have exit ports (120) at the end of the conductive paths on the first and the second surface. A cavity (130) extends downwardly from the first surface to a depth less than the thickness; the bottom of the cavity and the first substrate surface have contact pads (141). The substrate further has electrically conductive lines (150) between the first and the second surface and under the cavity, contacting the paths. The system includes a stack of semiconductor chips (160,170) with bond pads; one chip is attached to the bottom of the cavity and one chip is electrically connected to substrate contact pads.