Abstract: A copper conductive paint for use on a porcelanized metal substrate, which comprises a powder mixture of 82 to 98.5% copper, 0.5 to 12% copper hydroxide, and 1 to 6% non-reducable borosilicate glass frit. 75 to 90 percent of the powder mixture is blended with 10 to 25 percent screening agent to form the copper conductive paint herein disclosed. The copper conductive paint is then screened and fired upon a porcelainized metal substrate in an inert atmosphere at approximately 900.degree. C. to form a copper conductor exhibiting improved adhesion characteristics.

Abstract: Method and apparatus for fabricating composite porcelain substrates employing alternating layers of wire cloth and porcelain green sheet material are disclosed, wherein those alternating layers are compressed toward one another at a somewhat elevated temperature and then kiln fired at a further elevated temperature to form a glazed porcelain surface for receiving further electrical circuitry, for example, of the microelectronic type. Such a composite porcelain substrate has good thermal properties of high conductivity and low coefficient of expansion as well as good electrical insulating properties and mechanical strength. In particular its thermal expansion properties are well matched to many surface mounted devices that may be placed on the substrate thereby reducing the likelihood of thermal damage of device connections. The substrate cost is very low in comparison to the currently available alternatives.

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.

Abstract: An apparatus and process for producing fired resistors having uniform resistance characteristics, wherein a continuous closed-loop feedback network detects deviations from standard resistivity values and continuously corrects the composition by varying the proportions of high and low resistance material ratios or blends of such materials being screened onto the substrates (212), and detects deviations in screened-on film thickness for continuously correcting either the speed of operation of a screener assembly (No. 1, No. 2) or the squeegee head pressure in order to obtain a predetermined film thickness. The process continuously adjusts the resistance values through on-the-production-line control of mixture ratios of high and low resistive paints, to produce final fired resistors (170) having the required resistance values, temperature coefficients of resistivity, improved stability, and improved TCR tracking values.

Abstract: A vertical tunnel kiln (10) comprising a firing kiln (30) having a interior core (42) supporting a spiral chute (46) attached to the periphery of the core (42). A vibratory bowl feeder (20) automatically feeds parts (100) individually to the upper end (24) of the spiral chute (46), and the parts (100) progress down the chute by means of vibrations imparted to the interior core (42) and chute (46) by a vibratory mechanism (40) attached to the annular base (47). Heating elements (38) and (70) are disposed exteriorly and interiorly, respectively, about the interior core (42) to produce a temperature gradient. As the parts (100) advance along chute 46, resistive materials on the parts (100) are heated in the preheat section (54) to remove volatile organic materials, fired in the intermediate portion (55) of the firing kiln (30), and then cooled in the cooling portion (56). The parts (100) are removed individually by an escapement mechanism (80) attached to the lower end of the spiral chute (46).

Abstract: An apparatus and process for producing fired resistors having uniform resistance characteristics, wherein a continuous closed-loop feedback network detects deviations from standard resistivity values and continuously corrects the composition by varying the proportions of high and low resistance material ratios or blends of such materials being screened onto the substrates (212), and detects deviations in screened-on film thickness for continuously correcting either the speed of operation of a screener assembly (No. 1, No. 2) or the squeegee head pressure in order to obtain a predetermined film thickness. The process continuously adjusts the fired resistance values through on-the-production-line control of mixture ratios of high and low resistive paints, to produce final fired resistors (170) having the required resistance values, temperature coefficients of resistivity, improved stability, and improved TCR tracking values.

Abstract: A lateral exhaust manifold system for the preheat section of a tunnel kiln comprises a longitudinal duct and input tube. The duct is triangular in shape and has a plurality of spaced apart apertures and a corresponding plurality of cones, the large diameter end of each cone circumposing a respective one of said apertures. The input tube is disposed adjacent the opposite side of the tunnel kiln and has a plurality of spaced apart jets each disposed opposite a respective aperture in the longitudinal duct, and a plurality of spaced apart apertures each located intermediate the jets, the spaced apart apertures and for venting air laterally across the kiln and upwardly along the adjacent wall. A blower vents an exhaust stack connected to an end of the duct. Air curtains control the entrance and exit of the preheat section of the kiln.