Microwave/millimeter wave circuit structure with discrete flip-chip mounted elements, and method of fabricating the same

A method of fabricating a microwave/millimeter wave circuit structure, comprising:

• providing a non-ceramic and non-semiconductor dielectric substrate with an oxidizable electrical interconnection network and an array of conductive wettable contact pads at respective locations on said network, with pad dimensions and spacings between said pads that are compatible with signal wavelengths in at least part of the microwave/millimeter wave range, said pads being substantially non-oxidizable in a threshold environment for oxidizing said interconnection network,
• providing a plurality of discrete microwave/millimeter wave circuit elements with contact locations on said elements that correspond to respective contact pad locations on said substrate,
• oxidizing the surface of said interconnection network to a non-wettable surface in an environment that leaves said contact pads substantially wettable and non-oxidized, and
• flip chip mounting said circuit elements to said substrate with solder contact bumps that mechanically and electrically connect said circuit element contact locations with respective contact pads on said substrate, said mounting being accomplished by flowing said bumps onto said contact pads so that said contact pads self-align to their respective bumps during the mounting of said circuit elements, the oxidized surface of said interconnection network inhibiting a flow of said solder bumps onto said surface and thereby assisting said bumps and their associated circuit elements to self-align on said pads.