A polymeric positive temperature coefficient (PPTC) device including a PPTC body, a first electrode disposed on a first side of the PPTC body, and a second electrode disposed on a second side of the PPTC body, wherein the PPTC body is formed of a PPTC material that includes a polymer matrix and a conductive filler, wherein the conductive filler defines 20%-39% by volume of the PPTC material.

A composite electronic component includes: a first electronic component including a ceramic body having a main surface caused to face a circuit board at a time of mounting and first and second end surfaces orthogonal to the main surface, and a first external electrode and a second external electrode respectively provided to the first end surface and the second end surface and respectively extending from the first end surface and the second end surface to the main surface; and a second electronic component including a functional film provided to the main surface, and a first electrode film and a second electrode film provided to both end portions of the functional film separately from the first external electrode and the second external electrode, the second electronic component being configured to fit within a thickness of each of the first external electrode and the second external electrode from the main surface.

A polymeric positive temperature coefficient (PPTC) device including a PPTC body, a first electrode disposed on a first side of the PPTC body, and a second electrode disposed on a second side of the PPTC body, wherein the PPTC body is formed of a PPTC material that includes a polymer matrix and a conductive filler, wherein the conductive filler defines 20%-39% by volume of the PPTC material.

A resistor includes materials including copper, nickel, and lanthanum boride. A content of the materials is 40% by mass or more with respect to a total material content of the resistor. The copper includes copper particles having a particle diameter of 2.5 m or more. In addition, a circuit board includes a substrate, the resistor on the substrate, a metal layer on the resistor and a glass layer on the resistor. Further, an electronic device includes the circuit board and an electronic component on the metal layer.

A polymeric positive temperature coefficient (PPTC) device including a PPTC body, a first electrode disposed on a first side of the PPTC body, and a second electrode disposed on a second side of the PPTC body, wherein the PPTC body is formed of a PPTC material that includes a polymer matrix and a conductive filler, wherein the conductive filler defines 20%-39% by volume of the PPTC material.

A resistor includes materials including copper, nickel, and lanthanum boride. A content of the materials is 40% by mass or more with respect to a total material content of the resistor. The copper includes copper particles having a particle diameter of 2.5 m or more. In addition, a circuit board includes a substrate, the resistor on the substrate, a metal layer on the resistor and a glass layer on the resistor. Further, an electronic device includes the circuit board and an electronic component on the metal layer.

A polymeric positive temperature coefficient (PPTC) device including a PPTC body, a first electrode disposed on a first side of the PPTC body, and a second electrode disposed on a second side of the PPTC body, wherein the PPTC body is formed of a PPTC material that includes a polymer matrix and a conductive filler, wherein the conductive filler defines 20%-39% by volume of the PPTC material.

A composite electronic component includes: a first electronic component including a ceramic body having a main surface caused to face a circuit board at a time of mounting and first and second end surfaces orthogonal to the main surface, and a first external electrode and a second external electrode respectively provided to the first end surface and the second end surface and respectively extending from the first end surface and the second end surface to the main surface; and a second electronic component including a functional film provided to the main surface, and a first electrode film and a second electrode film provided to both end portions of the functional film separately from the first external electrode and the second external electrode, the second electronic component being configured to fit within a thickness of each of the first external electrode and the second external electrode from the main surface.

An over-current protection device comprises first and second electrode layers and a PTC material layer laminated therebetween. The PTC material layer has a resistivity less than 0.05 .Math.cm and comprises a polymer matrix, a conductive ceramic filler and a carbon-containing conductive filler. The polymer matrix comprises a fluoropolymer having a melting point higher than 150 C. and comprises 50-60% by volume of the PTC material layer. The conductive ceramic filler having a resistivity less than 500.Math.cm is dispersed in the polymer matrix and comprises 40-45% by volume of the PTC material layer. The carbon-containing conductive filler is dispersed in the polymer matrix and comprises 0.5-5% by volume of the PTC material layer. At 25 C., a ratio of a hold current to an area of the over-current protection device is 0.21-0.3 A/mm.sup.2, and a ratio of an endurable power to the area of the over-current protection device is 4.8-7.2 W/mm.sup.2.

An apparatus includes a first layer of a rare earth element. The apparatus further includes a thin-film coating layer deposited on the first layer, where the thin-film coating layer includes boron.