Provided are a core electric wire for multi-core cable that is superior in flex resistance at low temperature, and a multi-core cable employing the same. A core electric wire for multi-core cable according to an aspect of the present invention comprises a conductor obtained by twisting element wires, and an insulating layer that covers an outer periphery of the conductor, in which, in a transverse cross section of the conductor, a percentage of an area occupied by void regions among the element wires is from 5% to 20%. An average area of the conductor in the transverse cross section is preferably from 1.0 mm.sup.2 to 3.0 mm.sup.2. An average diameter of the element wires in the conductor is preferably from 40 m to 100 m, and the number of the element wires is preferably from 196 to 2,450. The conductor is preferably obtained by twisting stranded element wires obtained by twisting subsets of element wires. The insulating layer preferably comprises as a principal component a copolymer of ethylene and an -olefin having a carbonyl group.

An insulated electric wire includes a linear conductor and one or a plurality of insulating layers formed on an outer peripheral surface of the conductor. At least one of the one or plurality of insulating layers contains a plurality of pores, outer shells are disposed on peripheries of the pores, and the outer shells are derived from shells of hollow-forming particles having a core-shell structure. A varnish for forming an insulating layer contains a resin composition forming a matrix and hollow-forming particles having a core-shell structure and dispersed in the resin composition. In the varnish, cores of the hollow-forming particles contain a thermally decomposable resin as a main component, and shells of the hollow-forming particles contain a main component having a higher thermal decomposition temperature than the thermally decomposable resin.

An electrical cable manufacturing method includes: in a joining device including a first facing surface and a second facing surface facing each other in a first direction, and a pressing member and a vibrating member facing each other in a second direction, setting an interval between the first facing surface and the second facing surface to a first distance; placing core wires between the first facing surface and the second facing surface having the interval set at the first distance; and joining the core wires by ultrasonic vibration. The core wires include core wires having different outer diameters. The first distance is larger than a maximum value between values of outer diameters of the core wires and smaller than the sum of the maximum value and a minimum value.

A printed circuit board comprises a substrate and a routing structure arranged on the substrate, the substrate has a welding region and a routing region electrical connected with the welding region. The routing structure comprises a plurality of bonding pads connected with corresponding wires and a plurality of conductive traces electrically connected with the bonding pads, the bonding pads is arranged in the welding region, and the conductive traces are disposed in both the welding region and the routing region. The bonding pads are arranged abreast, and in the arrangement direction of the bonding pads, the bonding pads defines at least two grounding pads for connecting with grounding wires and at least a signal pad between the two grounding pads.

A flat data transmission cable includes a plurality of juxtaposed wires and a plastic layer enclosing on the wires integrally, each wire has a conductor. Central axes of the conductors are located on a same plane, and the plastic layer defines a top surface and a bottom surface parallel to the plane in which the central axes of the conductors located, the wires define at least two grounding wires and at least a signal wire between the two grounding wires.

A flat data transmission cable includes a plurality of juxtaposed wires, a plastic layer enclosing on the wires integrally and a metallic layer formed by a metal material belt arranged on an outer side of the plastic layer in a spiral winding way. In the length direction of the data transmission cable, the data transmission cable has at least one bending portion, the data transmission cable is formed with a first section and a second section on both sides of the bending portion, and a stable bending angle is formed between the first section and the second section.

A flat data transmission cable includes a plurality of juxtaposed wires, a plastic layer enclosing on the wires integrally and a metallic layer formed by a metal material belt arranged on an outer side of the plastic layer in a spiral winding way, each wire has a conductor. The metallic layer has at least an aluminum foil layer and a bonding layer arranged on the side of the aluminum foil layer facing to the plastic layer, the metallic layer is bonded to the outer side of the plastic layer by the bonding layer.

Provided are a core electric wire for multi-core cable that is superior in flex resistance at low temperature, and a multi-core cable employing the same. A core electric wire for multi-core cable according to an aspect of the present invention comprises a conductor obtained by twisting element wires, and an insulating layer that covers an outer periphery of the conductor, in which, in a transverse cross section of the conductor, a percentage of an area occupied by void regions among the element wires is from 5% to 20%. An average area of the conductor in the transverse cross section is preferably from 1.0 mm.sup.2 to 3.0 mm.sup.2. An average diameter of the element wires in the conductor is preferably from 40 m to 100 m, and the number of the element wires is preferably from 196 to 2,450. The conductor is preferably obtained by twisting stranded element wires obtained by twisting subsets of element wires. The insulating layer preferably comprises as a principal component a copolymer of ethylene and an -olefin having a carbonyl group.

A shrinkable cable joint includes a joint insulating layer that surrounds a connection region configured to house two connected cable ends. A joint semiconductive layer surrounds the joint insulating layer. A joint screen layer surrounds the joint semiconductive layer. A joint sheath surrounds the joint screen layer. A capacitive voltage sensor is arranged between the joint screen layer and the joint semiconductive layer. The capacitive voltage sensor includes a sensor insulating layer having a first side and an opposite second side; a sensor electrode and a guard electrode arranged on the second side and directly contacting the joint semiconductive layer; and a sensor conductive layer arranged on the first side. The sensor conductive layer includes a first conductive layer portion in direct contact with the joint screen layer and electrically coupled to the guard electrode and a second conductive layer portion electrically coupled to the sensor electrode.

An electrical cable includes a conductor assembly having a first conductor, a second conductor and an insulator surrounding the first conductor and the second conductor. The insulator has an outer surface. The conductor assembly extends along a longitudinal axis for a length of the electrical cable. The first conductor has a first core and a first conductive layer on the first core. The second conductor has a second core and a second conductive layer on the second core. The first and second cores are dielectric. The electrical cable includes a cable shield around the conductor assembly engaging the outer surface of the insulator and providing electrical shielding for the first and second conductors. The cable shield extends along the longitudinal axis.