Abstract: A circuit board assembly that makes use of a low-temperature co-fired ceramic (LTCC) substrate, and a process for producing the assembly. The substrate contains at least first and second regions formed by a plurality of first ceramic layers and at least one second ceramic layer, respectively, that are superimposed and bonded to each other. Conductor lines are present on at least some of the first ceramic layers so as to be between adjacent pairs of the layers. Electrically-conductive vias electrically interconnect the conductor lines on different first ceramic layers, and a surface-mount IC device is mounted to the substrate. The first ceramic layers are formed of electrically-nonconductive materials, while the one or more second ceramic layers contain thermally-conductive particles dispersed in a matrix of electrically-nonconductive materials, such that the one or more second ceramic layers are more thermally conductive than the first ceramic layers.

Abstract: A circuit board assembly that makes use of a low-temperature co-fired ceramic (LTCC) substrate, and a process for producing the assembly. The substrate contains at least first and second regions formed by a plurality of first ceramic layers and at least one second ceramic layer, respectively, that are superimposed and bonded to each other. Conductor lines are present on at least some of the first ceramic layers so as to be between adjacent pairs of the layers. Electrically-conductive vias electrically interconnect the conductor lines on different first ceramic layers, and a surface-mount IC device is mounted to the substrate. The first ceramic layers are formed of electrically-nonconductive materials, while the one or more second ceramic layers contain thermally-conductive particles dispersed in a matrix of electrically-non-conductive materials, such that the one or more second ceramic layers are more thermally conductive than the first ceramic layers.

Abstract: A thick-film paste for printing thick-film circuit elements, including solder stops, conductors, resistors and capacitors, and a method for using the paste. The paste has a composition that includes an organic vehicle, a filler material that contributes the desired electrical and/or material properties to the thick film fired from the paste, and an additive that is insoluble in the organic vehicle and contributes pseudoplastic Theological properties to the paste during printing. The additive also preferably evaporates, burns off, sublimates or is otherwise removed below the firing temperature of the paste.

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 method by which a conventional circuit trace (14) is modified with a layer (16) of high-conductivity solder alloy to yield a high-current circuit trace (12) for high-current routing on a substrate (10). The method generally entails the use of a solder composition that contains a dispersion of metal particles (18) in a solder alloy (20). The metal particles (18) are selected on the basis of having a higher electrical conductivity than the solder alloy (20), and are present in sufficient amounts so that the electrical conductivity of the solder composition is significantly higher than that of the solder alloy (20). The solder composition is deposited on a conductor (14), and then reflowed to form a conductive layer (16) on the conductor (14). The metal particles (18) remain as a discrete dispersion within the conductive layer (16) in order to suitably promote the conductivity of the layer (16).

Abstract: A thick-film conductor paste and thick-film conductors formed therefrom. The conductor paste is composed of metallic particles coated with a barrier layer that reduces leaching and solder diffusion into the conductor, thereby improving the reliability of the conductor-solder bond. The barrier layer may be continuous or discontinuous, and may be applied to some or all of the metallic particles of the conductor paste.

Abstract: A thick film hybrid multilayer circuit characterized by circuit components that are electrically interconnected with a multilayer structure composed of multiple layers of conductors interlaid with layers of a dielectric material in order to achieve high component density. The circuit components of the hybrid circuit are bonded to the multilayer structure with a novel soldering technique employing multiple solder compositions, which reduces the occurrence of dielectric fatigue cracking from thermal cycling. As a result, the multilayer structure exhibits significantly enhanced thermal fatigue resistance.

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.

Abstract: A thick-film conductor paste and thick-film conductors formed therefrom. The conductor paste is composed of metallic particles coated with a ceramic layer that reduces leaching and solder diffusion into the conductor, thereby improving the reliability of the conductor-solder bond. The ceramic layer may be continuous or discontinuous, and may be applied to some or all of the particles of the conductor paste.