Abstract: The adjustment of the temperature coefficient of resistance (TCR) of a thick film resistor by laser annealing is disclosed. The thick film resistor is fired for a controlled time and temperature sufficient to burn off the organic material in the resistive paint, and to provide an initial adjustment of the (TCR), but prior to obtaining the desired (TCR) range. The resistor is then laser annealed to controllably adjust the (TCR) of the resistor within the desired (TCR) range. The fixture used to hold the substrate during laser annealing is preferably controllably heated to avoid thermal shock to the resistor during laser annealing. A microprocessor is preferably used to monitor the (TCR) during the laser annealing process. At least one of the laser scan speed, laser beam diameter, laser beam power, and number of annealing passes are used to controllably adjust the resistor (TCR) to within the desired (TCR) range.

Abstract: A flexible porcelain tape (10) is manufactured for application to a metal substrate (50) to produce a porcelainized metal substrate (60, 90, 92). The porcelain tape (10) provides an insulative layer (102) upon which can be applied electrical circuits (110) comprising conductive paths (112) and resistors (116), either before or after the porcelain tape (10) is fired. The porcelain tape comprises glass frit (12) blended with a vehicle (11), with volatile gases removed to effect a predetermined viscosity. The mixture (14) is applied evenly to a flexible plastic carrier (16) and dried. The tape (10) may be rolled up and stored until needed, whereupon the flexible carrier (16) is peeled away either before or after the porcelain mixture layer (18) is cut to desired size and configuration. Single or multiple layers of the mixture layer (18) can be disposed upon a metal substrate (50), the combination laminated, and then fired.