A positive temperature coefficient ceramic thermistor element includes a sintered thermosensitive ceramic piece that uses lead barium titanate as a base, as well as metal ohmic electrodes which are positioned on two side surfaces of the thermosensitive ceramic piece. The thermistor element has a microporous channel barrier layer, and includes a glass sealing layer which wraps the outer surface of the thermosensitive ceramic piece, or an organic matter sealant which fills and blocks micro-pores in the surfaces of the metal ohmic electrodes combined on the two side surfaces of the thermosensitive ceramic piece and, at the same time, blocks gaps in the surfaces of areas, that do not have the metal ohmic electrodes, of a peripheral edge of the thermosensitive ceramic piece.

A method of sintering solderable base metals in air atmosphere and manufacturing alloy components to manufacture solderable electrodes by heat treatment instead of electroplating processes. The method involves introducing into an electrode plenty of metallic tin powder directly, then metallic aluminum powder with high-oxidation enthalpy formation to protect tin against oxidation, and other metals, say metallic copper powder, to produce copper-tin alloy to increase the melting point of the electrode. With the method, tin, as a base, directly functions as an electrode, covering the tin electrode with aluminum film to protect the tin electrode against oxidation during heat treatment, introducing appropriate metals, say copper, into the tin film to produce alloy from tin and copper to increase the melting point of the electrode. With electroplating processes replaced by heat treatment, electronic components, i.e., electrodes, are manufactured without any tin electroplating process but exhibit high solderability and excellent functionality.

A chip ceramic semiconductor electronic component includes a ceramic body including a ceramic semiconductor, and a first surface and a second surface in contact with the first surface, the first outer electrode on the first surface of the ceramic body, and the second outer electrode covering the first outer electrode and extending onto the second surface of the ceramic body, in which an area of a first surface of the first outer electrode is less than about 0.17 mm.sup.2, and a hard particle made of a material harder than the first outer electrode is at the interface between the first and second outer electrodes.

An over-current protection device comprises first and second electrode layers and a PTC material layer laminated therebetween. The PTC material layer includes a polymer matrix, a conductive filler and a titanium-containing inner filler. The polymer matrix has a fluorine-free polyolefin-based polymer. The titanium-containing inner filler has a compound represented by a general formula of MTiO.sub.3, wherein the M represents transition metal or alkaline earth metal. The total volume of the PTC material layer is calculated as 100%, and the titanium-containing inner filler accounts for 1-9% by volume of the PTC material layer.

A circuit protection device includes a first temperature sensitive resistor, a second temperature sensitive resistor, an electrically insulating multilayer, a first and second electrode layer, and at least one external electrode. The first temperature sensitive resistor and the second temperature sensitive resistor are electrically connected in parallel, and have a first upper electrically conductive layer and a second lower electrically conductive layer, respectively. The electrically insulating multilayer includes an upper insulating layer, a middle insulating layer, and a lower insulating layer. The upper insulating layer is between the first upper electrically conductive layer and the first electrode layer. The middle layer is laminated between the first temperature sensitive resistor and the second temperature sensitive resistor. The lower insulating layer is between the second lower electrically conductive layer and the second electrode layer. The external electrode is disposed on the first electrode layer, and extends beyond a peripheral wall along a horizontal direction.

A positive temperature coefficient (PTC) heater is disclosed. In an embodiment the PTC heater includes a main body having a length L, a width B, and a height H made of a PTC material and a first electrode and a second electrode made of an electrically conductive material, wherein the following is true for L, B, and H: LBH, and wherein the electrodes are connected to the main body so that the following is true for a spacing d thereof from one another: d>H.

This disclosure refers to a method for confectioning resistors that each comprise a PTC ceramic plate and metallic electrode layers covering opposite faces of the ceramic plate, said method comprising the following steps: measuring an electrical resistance of a resistor to be confectioned by applying an electrical potential to one of electrode layers such that an electric current flows from one of the electrode layers through the ceramic plate to the electrode layer on the opposite face of the ceramic plate, comparing the measured resistance to a target resistance, and removing, if the measured resistance is lower than the target resistance, a section of at least one of the electrode layers. This disclosure also refers to such a resistor and a heating device comprising such resistors.

A three-dimensional electrode for a reflowable PTC device is provided. The three-dimensional electrode can include a planar portion for connecting with a PTC material on a top surface thereof or a bottom surface thereof, at least one expander portion electrically and physically connected with and perpendicular with the planar portion, and one or more terminals electrically and physically connected with the at least one expander portion, wherein the at least one expander portion can vertically or horizontally offset the one or more terminals from the planar portion.

A novel polymer positive temperature coefficient (PPTC) material, device, and method of fabrication. The PPTC device may include a PPTC body; a first electrode disposed on a first surface of the PPTC body and a second electrode disposed on a second surface of the PPTC body, opposite the first electrode. The PPTC body may include a polymer matrix; and a conductive filler, disposed in the polymer matrix. The conductive filler may include a tungsten carbide component comprising at least 30 volume percent of the PPTC body; and a carbon component, wherein a total volume fraction of the conductive filler comprises between forty volume percent and sixty five volume percent of the PPTC body.

A PTC device includes a protection component and an electrode connected to the protection component. The electrode includes first and second conductive materials. The first conductive material is adjacent the protection component and the second conductive material such that the first conductive material is sandwiched between the two. The first conductive material and the second conductive material prevent solder from touching the protective component.