Multilayer ceramic circuit boards with embedded resistors
AssigneesSarnoff Corporation, Sharp Kabushiki Kaisha
InventorsEllen Schwartz Tormey, Ashok Narayan Prabhu, Ponnusamy Palinasamy
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Abstract
Resistors can be screen printed onto a green tape stack from a resistor ink comprising ruthenium oxide and a sufficient amount of a low melting temperature glass so that the resultant mixture fires at a temperature of 850-900° C. A conductive layer, as of silver, terminates the screen printed resistor layer and one or two green tapes are applied over the resistor layer to embed the resistors during firing. A final conductive layer is applied after firing.
Claims9
A ceramic multilayer printed circuit board including embedded resistors comprising a screen printed resistor layer of ruthenium oxide and a low firing temperature glass selected from the group consisting of a glass comprising 3-7 percent by weight of alumina, about 30 to 40 percent by weight of boron oxide, from about 3-7 percent by weight of calcium oxide and about 45 to 55 percent by weight of zinc oxide and a glass comprising 10-35 percent by weight of boron oxide, about 10 to 30 percent by weight of magnesium oxide, about 10 to 40 percent by weight of silica and about 20-55 percent by weight of zinc oxide, said resistor layer having resistor value of from 300 ohm/sq to 100 Kohms/sq and a TCR less than or equal to 200 ppm/° C. over a temperature range of room temperature to 125° C. and printed onto a green tape stack laminated to a metal support board and covered with one or two green tape layers that are coated with a conductive metal layer.
Dependencies are inferred from the claim text.