Abstract: The present invention provides an ESD apparatus that includes an electrical overstress suppression device in series with a capacitor. The ESD apparatus is ideally suited for use with network communication devices, but any electronic device requiring overvoltage protection and isolation may employ the ESD apparatus of the present invention. In one embodiment, the ESD apparatus includes a capacitor and an electrical overstress protection device that electrically communicates in series with the capacitor. In another embodiment, the ESD apparatus includes an electrical overstress protection device having a voltage variable material and a capacitor that electrically communicates in series with the overstress protection device. The capacitor is sized so that the overstress device can withstand an application of a predetermined steady state voltage.

Abstract: The present invention provides a multifunction resistor having an improved voltage variable material (“VVM”). More specifically, the present invention provides a polymer VVM that has been formulated with a high percentage loading of conductive and/or semiconductive particles. A known length of the relatively conductive VVM is placed between adjacent electrodes to produce a desired Ohmic normal state resistance. When an electrostatic discharge event occurs, the VVM of the multifunctional resistor becomes highly conductive and dissipates the ESD threat. One application for this “resistor” is the termination of a transmission line, which prevents unwanted reflections and distortion of high frequency signals.

Abstract: A process for forming a thixotropic ink for use in manufacturing the ceramic of a zinc oxide varistor where the ceramic includes zinc, oxygen and a plurality of additive elements. The process includes the steps of calcining a mixture of powders of zinc oxide and the additive elements to form a calcined product having a particle size larger than the particle size of the zinc ozide powders, mixing said calcined product with an organic liquid, mechanically working the mixture to produce a calcined particulate material in the organic liquid having a particle size less than the particle size of said calcined product, adding an organic binder to the mixture and mixing the composition to produce said ink.

Abstract: A low profile mount for a disc varistor. A thermally sensitive switch is provided both for single and multiple electrode embodiments. The switch may be placed in a shorting circuit and include a spring biased conductor prevented from closure by a heat sensitive element which softens in responsive to excessive heat. The varistor may be fused to prevent excessive current from a short circuited but not open circuited varistor. Methods are also provided.

Abstract: A shield for an electrical fuse, including an inner enclosure for housing the electrical fuse and a pair of outwardly flaring end portions extending from the opposite ends of the enclosure. The shield includes walls separating the inner enclosure from each of the outwardly flaring end portions, and a slot in the walls for the extension through that slot of at least a terminal portion of the electrical fuse. The shield may be made of a pair of identical housing pieces with mating tongue and groove elements disposed substantially along the peripheries of those pieces. Preferably, the tongue element of the housing pieces is disposed on the opposite side as the groove element of the housing piece. Each of the outwardly flaring ends, or alternatively the walls, may cooperatively form a seal to aid in preventing entry of moisture or dirt into the shield. A sealing portion that aids in forming the seal may comprise a resilient, compressible grommet.

Abstract: A number of integrated circuit dies having on board protection against electrical overstress (EOS) transients are provided. Generally, the devices have an integrated circuit die with an outer periphery and a functional die area. A plurality of conductive input/output pads are formed on the integrated circuit die. Typically, a first conductive guard rail is disposed on the integrated circuit die and forms a gap between each one of the input/output pads. A voltage variable material is disposed in the gaps between the conductive guard rail and the input/output pads. Typically, a plurality of electrical leads are electrically connected to a respective one of the plurality of conductive input/output pads. At normal operating voltages, the voltage variable material is non-conductive. However, in response to an EOS transient, the voltage variable material switches to a low resistance state, providing a conductive path between the conductive guard rail and the input/output pads.

Abstract: A composition and devices utilizing these compositions for providing protection against electrical overstress including a matrix formed of a mixture of an insulating binder, conductive particles having an average particle size of less than 10 microns, and semiconductive particles having an average particle size of less than 10 microns. The compositions exhibit improved clamping voltages in a range of about 30 volts to greater than 2,000 volts.

Abstract: Apparatus for producing multilayer varistors using ceramic ink and electrode ink consists of a succession of stations, in which alternating layers of ceramic ink and electrode ink are laid down on a substrate. The stations may be printing stations in which either a ceramic ink screen or an electrode ink screen is used to apply the appropriate ink to the substrate. In a first printing step, a layer of ceramic ink is laid down, within a region determined by a mask area of a ceramic ink screen. In the following step, electrode ink is laid down in regions determined by mask areas of the electrode ink screen. The apparatus includes transfer mechanisms for advancing substrates from station to station for successive printing operations, and control mechanisms for regulating and coordinating the successive printing operations and substrate travel.

Abstract: The surface mountable electrical device provides utilizes polymer composite materials to protect electronic components against electrical overstress transients. The device includes a first substrate having an electrode formed thereon. A portion of the electrode forms an electrical connector which projects outwardly from the substrate. A second substrate has a electrode formed on a surface thereof. A portion of the electrode on the second substrate forms a well or cavity. A voltage variable material is disposed within the cavity formed in the electrode on the second substrate. The two substrates are laminated together such that the electrical connector extends into the voltage variable material disposed within the cavity. Outer terminations adapted to be connected to an electrical circuit are formed on the outer surfaces of the substrates and are electrically connected to each respective electrode.

Abstract: The present invention is a device for protecting an electrical circuit. The device includes a resistive element having a first and a second surface. A first electrode is in electrical contact with the first surface of the resistive element and a second electrode is in electrical contact with the second surface of the resistive element. A first end termination electrically connects the circuit and the first electrode. A second end termination electrically connects the second electrode and the circuit. An electrically insulating layer is interposed between the first and second end terminations and is in contact with the first and second electrodes. The end terminations allow for an electrical connection to be made to both electrodes from the same side of the electrical device.

Abstract: Electrical devices having a PTC element of a polymer having conductive particles dispersed therein. The PTC element is coated with a conductive layer and has electrodes with a plurality of voids affixed to opposing surfaces. The devices are made by dispersing conductive particles into a polymer to form a polymer PTC composition. The polymer PTC composition is melt-shaped to form a laminar shaped PTC element. First and second opposing surfaces of the PTC element are coated with a conductive layer. The electrodes, characterized by a plurality of voids and made of foam, are brought into contact with the coated surfaces of the PTC element, and heated while applying pressure to form a laminate. The laminate is then further shaped into a plurality of PTC electrical circuit protection devices.

Abstract: Electrical devices comprising a PTC element comprised of a polymer having conductive particles dispersed therein. The PTC element is coated with a conductive layer and has electrodes with a plurality of voids affixed to opposing surfaces. The devices are made by dispersing conductive particles into a polymer to form a polymer PTC composition. The polymer PTC composition is melt-shaped to form a laminar shaped PTC element. First and second opposing surfaces of the PTC element are coated with a conductive layer. The electrodes, characterized by a plurality of voids, are brought into contact with the coated surfaces of the PTC element, and heated while applying pressure to form a laminate. The laminate is then further shaped into a plurality of PTC electrical circuit protection devices.

Abstract: Circuit protection devices comprising PTC elements and circuits containing such devices. The PTC element includes a crystalline conductive polymer composition comprising a conductive particulate filler grafted to a modified polyolefin. The modified polyolefin comprises a polyolefin having a carboxylic acid or a carboxylic acid derivative grafted thereto. The conductive particulate filler is grafted via an esterification reaction to the modified polyolefin.

Abstract: A thin film surface-mount fuse having two material subassemblies. The first subassembly includes a fusible link, its supporting substrate with a groove on side surfaces and a plurality of conductive terminal pad layers. The second subassembly includes a protective layer which overlies the fusible link so as to provide protection from impacts and oxidation. The protective layer is preferably made of a polymeric material. The most preferred polymeric material is a polyurethane gel or paste. In addition, the most preferred supporting substrate is an FR-4 epoxy or a polyimide.

Abstract: A resettable circuit breaker for protecting an electrical circuit from prolonged overload current conditions. The resettable breaker opens upon prolonged overload current conditions. With an optional resistor, the resettable breaker remains open until the prolonged overload current is removed from the breaker. The breaker comprises a first stationary terminal having a first contact, and a movable terminal comprised of a single metal and having a second contact for engagement, under normal conditions, with the first contact. A shape memory alloy wire is positioned adjacent the movable terminal. The shape memory alloy wire is normally in a relaxed, non-contracted configuration. Upon prolonged overload current conditions, the shape memory alloy wire is heated and contracts to contact and shift the movable terminal and the second contact out of engagement with the first contact.

Abstract: A surge resistor fuse having an exposed pair of terminals for connection to an external circuit comprising an insulating housing having an exterior and an interior, a resistor element designed to interrupt the circuit when a surge of current passing through the resistor element exceeds a given energy level, and a fusing element designed to fuse under short circuit conditions and certain prolonged overload conditions, wherein the resisting element and the fusing element are connected in series and are mounted within a common enclosure.

Abstract: A fuse is provided which has a fuse housing with a transparent portion thereof, and a fuse element extending through the housing which is coated with a preferably non-hazardous temperature-responsive material. The temperature conditions generated at the interface between the coating and the fuse element cause the coating to leave the fuse element and deposit upon this transparent portion of the housing. The temperature-responsive coating on the fuse element will be transferred to the housing walls even where modest current overloads flow which do not immediately open the fuse. Different circuit overload conditions, including short circuit events, produce different visual indications or colorations on the transparent housings inside surfaces, which serves to identify the nature and degree of the overload problem existing in the circuit. Coatings, also capable of fluorescing under specific irradiation conditions, may be used.