Abstract: An article and method for making and repairing connections between first and second circuits, such as flex circuits. The article 10 includes: a flexible dielectric substrate 12 having first and second edges 14/16, and a plurality of conductive circuit traces 18 arranged on or within the substrate, wherein each of the traces extends from proximate the first edge 14 to proximate the second edge 16. Each of the circuit traces 18 includes: a first connection feature 20 disposed proximate the first edge 14; a second connection feature 22 disposed proximate the second edge 16; and at least one third connection feature 24 disposed between the first and second edges 14/16. Each of the first, second, and third connection features 20/22/24 is a plated through hole, a plated blind via, or a mounting pad. This article 10 may be used to connect together the first and second circuits 50/60 using the first and second connection features 20/22, such as by soldering.

Abstract: A method for making a multi-layer circuit board 116 having apertures 96, 98 which may be selectively and electrically isolated from electrically grounded member 46 and further having selectively formed air bridges and/or crossover members 104 which are structurally supported by material 112. Each of the apertures 96, 98 selectively receives electrically conductive material 114.

Abstract: A chemical etching manufacturing system is provided for removing material from a workpiece comprising a fluid control device, wherein the fluid control device controls at least one of fluid flow and fluid pressure, a fluid injection device, and a pulsed flow of chemical etchant adapted to pulsedly contact and remove material from a workpiece, wherein the pulse of the pulsed flow of chemical etchant is controlled by the fluid control device, and the pulsed flow of chemical etchant is emitted from the fluid injection device. A method of chemical etching in a manufacturing system is also provided comprising providing a workpiece, introducing the workpiece to a pulsed flow of chemical etchant, wherein the flow of chemical etchant pulsedly contacts and removes material from the workpiece, and removing the workpiece from the pulsed flow of chemical etchant.

Abstract: An article and method for making and repairing connections between first and second circuits, such as flex circuits. The article 10 includes: a flexible dielectric substrate 12 having first and second edges 14/16, and a plurality of conductive circuit traces 18 arranged on or within the substrate, wherein each of the traces extends from proximate the first edge 14 to proximate the second edge 16. Each of the circuit traces 18 includes: a first connection feature 20 disposed proximate the first edge 14; a second connection feature 22 disposed proximate the second edge 16; and at least one third connection feature 24 disposed between the first and second edges 14/16. Each of the first, second, and third connection features 20/22/24 is a plated through hole, a plated blind via, or a mounting pad. This article 10 may be used to connect together the first and second circuits 50/60 using the first and second connection features 20/22, such as by soldering.

Abstract: A multi-connectable printed circuit assembly, comprising: (a) a printed circuit substrate 11 having a first edge 22 and first and second edge regions 44/55, wherein at least the first edge region 44 is defined along the first edge 22; (b) a first array 77 of electrical connection features 66 disposed on or within the substrate proximate the first edge region 44; (c) a second array 88 of electrical connection features 66 disposed on or within the substrate proximate the second edge region 55, wherein the second array 88 is substantially a duplication or a mirror image of the first array 77; and (d) a plurality of circuit traces 99 disposed on or within the substrate such that each electrical connection feature 66 of the first array 77 is connected by one of the circuit traces 99 to a corresponding electrical connection feature 66 of the second array 88.

Abstract: A method which utilizes flip chip technology to provide interconnection between printed circuit boards and integrated circuits is disclosed. The method involves metallization of the bond pad and multiple, novel bump compositions and coating compositions to provide an interconnection which is reliable and which withstands differences in the coefficient of thermal expansion between the silicon device and the bump material.

Abstract: A multi-connectable printed circuit assembly, comprising: (a) a printed circuit substrate 11 having a first edge 22 and first and second edge regions 44/55, wherein at least the first edge region 44 is defined along the first edge 22; (b) a first array 77 of electrical connection features 66 disposed on or within the substrate proximate the first edge region 44; (c) a second array 88 of electrical connection features 66 disposed on or within the substrate proximate the second edge region 55, wherein the second array 88 is substantially a duplication or a mirror image of the first array 77; and (d) a plurality of circuit traces 99 disposed on or within the substrate such that each electrical connection feature 66 of the first array 77 is connected by one of the circuit traces 99 to a corresponding electrical connection feature 66 of the second array 88.

Abstract: The invention is an aluminum etchant and method for chemically milling aluminum from, according to a preferred embodiment, a copper-aluminum-copper tri-metal layer to form three-dimensional circuits. The tri-metal comprises copper circuit patterns present on opposing surfaces of an aluminum foil, one of the copper patterns being laminated on a substrate. The etchant comprises an aqueous solution of 60 to 500 g/l base selected from (a) sodium hydroxide, (b) potassium hydroxide, and (c) their mixture; and 30 to 500 g/l of an additive selected from nitrite salt, a borate salt, a bromate salt, or mixture of any of them. The method comprises contacting the tri-metal with the etchant at a temperature between 25 and 95° C. for a time sufficient to remove a desired amount of the aluminum layer and provide (rigid, flexible, or 3-dimensional) electronic circuitry which may contain multiple conductive circuit layers.

Abstract: A method which utilizes flip chip technology to provide interconnection between printed circuit boards and integrated circuits is disclosed. The method involves metallization of the bond pad and multiple, novel bump compositions and coating compositions to provide an interconnection which is reliable and which withstands differences in the coefficient of thermal expansion between the silicon device and the bump material.

Abstract: The invention is an aluminum etchant and method for chemically milling aluminum, according to one embodiment, from a copper-aluminum-copper tri-metal layer to form electronic circuits. The tri-metal comprises copper circuit patterns present on opposing surfaces of an aluminum foil, one of the copper patterns being laminated on a substrate. The etchant comprises an aqueous solution of 50 to 500 g/l base selected from (a) sodium hydroxide, (b) potassium hydroxide, and (c) their mixture; and 60 to 500 g/l nitrate salt. The method comprises contacting the tri-metal with the etchant at a temperature between 25 and 95.degree. C. for a time sufficient to remove a desired amount of the aluminum layer and provide electronic circuitry (rigid/flexible/3-dimensional circuitry) which contains multiple conductive circuit layers.

Abstract: A device which utilizes flip chip technology to provide interconnection between printed circuit boards and integrated circuits is disclosed. The method involves metallization of the bond pad and multiple, novel bump compositions and coating compositions to provide an interconnection which is reliable and which withstands differences in the coefficient of thermal expansion between the silicon device and the bump material.

Abstract: A soldering process is suitable for use with low cost, low heat distortion temperature thermoplastic substrates without distortion or damage to the substrate yet having the mass production capability exhibited by wave and reflow soldering techniques. The process allows integration of consumer products and, in particular, vehicle components such as integrated instrument panel or other such assemblies, without the redundancy of separate printed circuit boards.

Abstract: Low temperature electrical solder compositions (by weight percent) having between 45-60% Sn; 25-40% Pb; 5-15% Bi; and 0.5-2.5% In. Preferably, the solder compositions have a melting temperature of about 154.degree.-162.degree. C. The solder compositions have microstructure similarly to Sn/Pb eutectic microstructure which makes them have excellent properties like higher yield strength and better creep resistance providing long term reliability to solder joints.

Abstract: Electrical solder compositions (by weight percent) having between 91.5-96.5% Sn; 2-5% Ag; 0.1-3% Ni; and 0-2.9% Cu; and having a melting temperature 220.degree. C. or less. The solder compositions have microstructure with uniformly dispersed fine grains of Sn--Ni, Sn--Cu and Sn--Cu--Ni intermetallic phases that provide resistance to grain growth during thermal cycling.

Abstract: A non-toxic alloy for soldering electronic components comprising 80% Sn, 5-14.5% In, 4.5-14.5% Bi and 0.5% Ag. The disclosed alloy has a fine microstructure. Particles of intermetallic compounds are finely dispersed throughout the matrix, thereby inhibiting grain growth. Accordingly, the alloy does not significantly coarsen after thermal aging.

Abstract: An improved exhaust gas sensor for use in sensing the partial pressure of oxygen in the exhaust gases from an internal combustion engine. The sensor has a titania ceramic element in which two electrodes are embedded. The electrodes in the past have been made from pure platinum, this precious metal being required to enable the sensor electrodes to survive at temperatures up to about 900.degree. C. in the hostile gaseous environment. Even with the use of this platinum electrode material, electrode failures have occurred. These now have been found to be caused by the formation of platinum carbide from the chemical reaction of the platinum electrode material with exhaust gas constituents. Also, Pt loss has occurred from oxidation thereof and vaporization of the oxide. It has been found that deterioriation of sensor electrodes may be prevented by forming these electrodes from an alloy consisting essentially of platinum and another material having a lower vapor pressure and lower surface tension than platinum.

Abstract: An improved sensor having a ceramic element that undergoes a change in an electrical characteristic in response to a change in the partial pressure of oxygen in a mixture of gases to which the ceramic element is exposed. Sensors of this type are used to detect the air-fuel ratio of mixtures supplied to internal combustion engines. Prior art titania and zirconia sensors are characterized by little change in their respective electrical characteristics at operating temperatures below about 350.degree. C. A charge transfer material, platinum, has been applied to the ceramic element to facilitate or make possible the electron transfers required for sensor operation. Loss of the platinum charge transfer material by vaporization, as the result of operation at normal elevated temperatures, has been discovered to be the cause of a loss of sensor response at low sensor operating temperatures. The improved sensor has a charge transfer material comprised of an alloy of platinum and rhodium.