Thick film conductor paste compositions for LTCC tape in microwave applications
View Patent ↗This invention is related to thick film conductor compositions comprising electrically conductive gold powder, one or more glass frit or ceramic oxide compositions and an organic vehicle. It is further directed to the composition's uses for LTCC (low temperature co-fired ceramic) tape, for fabrication of multilayer electronic circuits and in high frequency microelectronic applications.
1. A thick film conductive composition for use in microwave applications comprising:
a) gold powder;
b) one or more inorganic binders selected from (1) glass frit, selected from the group consisting of 5-20 B 2 O 3 , 1-44 SiO 2 , 3-20 Al 2 O 3 , 0-10 Na 2 O, 0-4 Li 2 O, 2-41 P 2 O 5 , 5-16 NaF, 0-9 CaO, 0-3 ZrO 3 , 0-19 ZnO, 0-2 BaO, and 0-11 ZnF 2 (2) transition metal oxides and (3) precursors of transition metal oxides; and (4) mixtures thereof; and
c) organic medium
wherein said inorganic binders are lead free and cadmium free.
2. The composition of claim 1 wherein said inorganic binder is present in an amount of up to 3 weight percent, based on total thick film composition.
3. The composition of claim 1 comprising said glass frit in the range of 0 to 2.0 weight percent based on total thick film composition.
4. The composition of claim 1 wherein said transition metal oxide is present in the range of 0.2-0.6 weight percent total thick film composition.
5. The composition of claim 1 wherein said gold powder is present in the range of 60-90 weight percent based on total thick film composition.
6. The composition of claim 1 further comprising silver powder in the range of 0-3 weight percent based on total thick film composition.
7. The composition of claim 1 wherein said composition is compatible with low temperature co-fired ceramic tape.
8. The composition of claim 1 wherein said glass frit has a softening point in the range of 350 to 800° C.
9. A method of using the composition of claim 1 to form high frequency transmit/receive modules or radar, comprising a multilayer circuit comprising the following steps:
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 pattered thick film functional layers over a surface of some or all of the via-filled green tape layers of step (b);
d) laminating the printed green tape layers of step (c) to form an assemblage comprising a plurality of unfired interconnected functional layers separated by unfired green tape;
e) printing at least one patterned layer of the thick film composition of claim 1 over the assemblage of step (d); and
f) cofiring the assemblage and patterned layer(s) of step (e).
10. The method of using of claim 9 to form microwave circuit components selected from the group consisting of: antenna, filters, baluns, beam former, I/O's, couplers, via feedthroughs, EM coupled feedthroughs, wirebond connection, and transmission lines.