Patent ID: 7740725

Claim:
A method of forming a multilayer circuit comprising: a) forming a patterned array of vias in a plurality of layers of green tape; b) filling the vias in the green tape layer(s) of step a) with a thick film composition; c) printing patterned thick film functional layers over a surface of any or all of the via-filled green tape layers of step b); d) printing patterned layers of a thick film conductive composition over the outermost surface of the green tape layers of step c), the thick film conductive composition comprising: i) gold powder; ii) an inorganic binder of glass frit consisting of 5-20 wt % B 2 O 3 , 1-44 wt % SiO 2 , 3-20 wt % Al 2 O 3 , 0-10 wt % Na 2 O, 0-4 wt % Li 2 O, 2-41 wt % P 2 O 5 , 5-16 wt % NaF, 0-9 wt % CaO, 0-3 wt % ZrO 3 , 0-19 wt % ZnO, 0-2 wt % BaO, and 0-11 wt % ZnF 2 , wherein the weight percent are based on the total glass composition; and iii) organic medium; e) laminating the printed green tape layers of step d) to form an assemblage comprising a plurality of unfired interconnected functional layers separated by unfired green tape; and f) cofiring the assemblage of step e).