A thermistor includes a thermistor element, a protective film formed on the surface of the thermistor element, and electrode portions formed on both end portions of the thermistor element, in which the protective film is formed of silicon oxide, and, as a result of observing a bonding interface between the thermistor element and the protective film, a ratio L/L.sub.0 of a length L of an observed peeled portion to a length L.sub.0 of the bonding interface in an observation field is 0.16 or less.

The resistor includes a chip resistive element which includes a resistive element and metal electrodes and which is formed on first surface of a ceramic substrate, metal terminals electrically joined to the metal electrodes, and an Al member formed on the second surface side of the ceramic substrate, wherein the ceramic substrate and the Al member are joined using an Al—Si-based brazing filler metal, the metal electrodes and the metal terminals are joined to each other using a solder, and a degree of bending of an opposite surface of the Al member opposite to a surface on the ceramic substrate side is in a range of −30 μm/50 mm to 700 μm/50 mm.

The temperature sensor can have a core having a length extending between two ends, the core having a cavity extending along the length, a wire extending in the cavity, along the length, the wire fixed at both ends, the core having a transversal aperture at an intermediary location between the ends, the transversal aperture leading into the cavity, and a potting filling a portion of the cavity and supporting the wire at the intermediary location of the transversal aperture.

The temperature sensor can have a core having a length extending between two ends, the core having a cavity extending along the length, a wire extending in the cavity, along the length, the wire fixed at both ends, the core having a transversal aperture at an intermediary location between the ends, the transversal aperture leading into the cavity, and a potting filling a portion of the cavity and supporting the wire at the intermediary location of the transversal aperture.

A radial-leaded over-current protection device comprises a PTC element, a first electrode lead, a second electrode lead and an electrically insulating encapsulation layer. The PTC element comprises a first conductive layer, a second conductive layer and a PTC material layer laminated therebetween. The PTC material layer comprises crystalline polymer and conductive filler dispersed therein. The first electrode lead has an end connecting to the first conductive layer, whereas the second electrode lead has an end connecting to the second conductive layer. The electrically insulating encapsulation layer includes a fluorine-containing polymer, and wraps around an entire outer surface of the PTC element and the ends of the first and second electrodes connecting to the PTC element. The electrically insulating encapsulation layer has a thickness of 10.sup.2˜10.sup.5 nm, and the radial-leaded over-current protection device has an initial resistance R.sub.bf of 0.0017˜0.0027Ω.

One aspect is a resistor component for surface mounting on a printed circuit board, including a ceramic substrate with a first side and an opposite second side. A sinterable metallization is at least in some regions arranged on the second side. A resistance element comprising a metal layer is arranged at least in some regions on the first side of the ceramic substrate with a first connection and a second connection. An insulation layer is arranged at least in some regions on the resistance element and the ceramic substrate. A first region on the first connection and a second region on the second connection remain uncovered by the insulation layer. A first contact pad electrically contacts the first connection via the first region, and a second contact pad electrically contacts the second connection via the second region. The first contact pad at least in some regions covers a first surface region of the insulation layer and the second contact pad at least in some regions covers a second surface region of the insulation layer, and the first and the second contact pads are arranged spatially separated from one another on the insulation layer.

One aspect is a resistor component for surface mounting on a printed circuit board, including a ceramic substrate with a first side and an opposite second side. A sinterable metallization is at least in some regions arranged on the second side. A resistance element comprising a metal layer is arranged at least in some regions on the first side of the ceramic substrate with a first connection and a second connection. An insulation layer is arranged at least in some regions on the resistance element and the ceramic substrate. A first region on the first connection and a second region on the second connection remain uncovered by the insulation layer. A first contact pad electrically contacts the first connection via the first region, and a second contact pad electrically contacts the second connection via the second region. The first contact pad at least in some regions covers a first surface region of the insulation layer and the second contact pad at least in some regions covers a second surface region of the insulation layer, and the first and the second contact pads are arranged spatially separated from one another on the insulation layer.

A radial-leaded over-current protection device comprises a PTC element, a first electrode lead, a second electrode lead and an electrically insulating encapsulation layer. The PTC element comprises a first conductive layer, a second conductive layer and a PTC material layer laminated therebetween. The PTC material layer comprises crystalline polymer and conductive filler dispersed therein. The first electrode lead has an end connecting to the first conductive layer, whereas the second electrode lead has an end connecting to the second conductive layer. The electrically insulating encapsulation layer includes a fluorine-containing polymer, and wraps around an entire outer surface of the PTC element and the ends of the first and second electrodes connecting to the PTC element. The electrically insulating encapsulation layer has a thickness of 10.sup.2˜10.sup.5 nm, and the radial-leaded over-current protection device has an initial resistance R.sub.bf of 0.0017˜0.0027Ω.

A surface-mountable over-current protection device comprises at least one PTC material layer, a first conductive layer, a second conductive layer, a first electrode, a second electrode, an insulating layer, and a cover layer. The PTC material layer comprises crystalline polymer and conductive fillers dispersed therein. The first conductive layer and the second conductive layer are disposed on a first surface and a second surface of the PTC material layer, respectively. The first electrode and the second electrode are electrically connected to the first conductive layer and the second conductive layer, respectively. The insulating layer is disposed between the first electrode and the second electrode for insulation. The cover layer includes a fluorine-containing polymer, and wraps around an entire outer surface of the surface-mountable over-current protection device.

A chip resistor including: a rectangular parallelepiped insulating substrate; a strip-shaped resistor; a pair of front electrodes formed on a front surface of the resistor at both ends in the longitudinal direction; an insulating protective layer; and a pair of end face electrodes formed at both ends of the insulating substrate in the longitudinal direction, each of which is connected to each end face of the resistor, corresponding one of the front electrodes, and protective film; and a pair of external electrodes, wherein a cross-sectional shape of each of the front electrodes is almost a triangle in which a side of the end face has a maximum height, and a shape of an end face of each of the end face electrodes is almost a square.