Abstract: A thick-film conductor, a method for forming the conductor, and a method for attaching a surface-mount circuit device to the conductor with a solder connection. The conductor is formed of a thick-film conductive ink that would normally produce a solderable conductor, but is rendered unsolderable by additions of a fine inorganic particulate material. A solderable region, preferably a pillar, is then selectively formed on the unsolderable conductor to determine the distribution and height of the solder connection on the conductor. In order to suitably affect the solderability of the conductor, the particulate material is present as a fine dispersion and in a sufficient quantity, but not in quantities that significantly affect the electrical, mechanical and processing characteristics of the conductor.

Abstract: A hybrid circuit structure that includes a metal substrate, an inorganic electrical insulator layer and at least one inorganic thick-film passive circuit element, such as a thick-film resistor, capacitor or conductor. An interface layer is provided between the insulator layer and the circuit element to prevent the detrimental effects of interlayer diffusion. The composition of the interface layer is selected to prevent the diffusion of constituents from the inorganic insulator layer, and to have a CTE near that of the circuit element to reduce thermal fatigue. As a result, the passive circuit element can be formed of essentially any one of a number of conventional inorganic thick-film materials that are widely used on alumina substrates.

Abstract: A high temperature thick-film hybrid circuit is characterized by a surface-mount circuit component that is electrically interconnected with a conductor. The surface-mount circuit component of the thick-film hybrid circuit is bonded to the conductor with a soldering technique employing dual-solder layers. The dual-solder layers enable component attachment to the conductor at a temperature below the maximum processing temperature of the component, while forming a solder joint that exhibits suitable adhesion properties at temperatures in excess of 165.degree. C. The dual-solder layers can be chosen to inhibit tin diffusion from the solder, silver leaching from the conductor, and the formation of a brittle intermetallic at the solder-conductor interface.