The present invention provides to a wearable smart device having electrical wiring comprising a stretchable conductive composition having excellent in durability such as repeated bending properties and repeated twisting properties, a material for realizing the wearable smart device, and a method for producing the wearable start device. An electrical wiring including a fine line having an electrical line interval of 1 mm or less, preferably the line width of less than 1 mm, is formed by printing a paste for forming a stretchable conductor containing metal-based conductive particles and a non-crosslinked elastomer, and further dried and cured at a low temperature condition of 120 C. for 30 minutes. As a result, the wearable smart device having electrical wiring constituted by fine lines without sagging of the edge is obtained.

A stretchable mounting board that includes a stretchable substrate having a main surface, a stretchable wiring disposed on the main surface of the stretchable substrate, a mounting electrode section electrically connected to the stretchable wiring, solder electrically connected to the mounting electrode section and including bismuth and tin, and an electronic component electrically connected to the mounting electrode section with the solder interposed therebetween. The mounting electrode section has a first electrode layer on a side thereof facing the stretchable wiring and which includes bismuth and tin, and a second electrode layer on a side thereof facing the solder and which includes bismuth and tin. A concentration of the bismuth in the first electrode layer is lower than a concentration of the bismuth in the second electrode layer, and the concentration of the bismuth in the second electrode layer is constant along a thickness direction thereof.

An item may include fabric or other materials formed from intertwined strands of material. The item may include circuitry that produces signals. The strands of material may include non-conductive strands and conductive strands. The conductive strands may carry the signals produced by the circuitry. Each conductive strand may have a strand core, a conductive coating on the strand core, and an insulating layer on the conductive coating. The strand cores may be strands formed from polymer. The conductive coating may be formed from metal. Electrical connections may be made between intertwined conductive strands by selectively removing portions of the outer insulating layer to expose the conductive cores of overlapping conductive strands. A conductive material such as solder or conductive epoxy may be applied to the exposed portions of the conductive cores to electrically and mechanically connect the overlapping conductive strands.

An apparatus is disclosed for transferring a pattern of a composition containing particles of an electrically conductive material and a thermally activated adhesive from a surface of a flexible web to a surface of a substrate. The apparatus comprises: respective drive mechanisms for advancing the web and the substrate to a nip through which the web and the substrate pass at the same time and where a pressure roller acts to press the surfaces of the web and the substrate against one another, a heating station for heating at least one of the web and the substrate prior to, or during, passage through the nip, to a temperature at which the adhesive in the composition is activated, a cooling station for cooling the web after passage through the nip, and a separating device for peeling the web away from the substrate after passage through the cooling station, to leave the pattern of composition adhered to the surface of the substrate.

An item may include fabric or other materials formed from intertwined strands of material. The item may include circuitry that produces signals. The strands of material may include non-conductive strands and conductive strands. The conductive strands may carry the signals produced by the circuitry. Each conductive strand may have a strand core, a conductive coating on the strand core, and an insulating layer on the conductive coating. The strand cores may be strands formed from polymer. The conductive coating may be formed from metal. Electrical connections may be made between intertwined conductive strands by selectively removing portions of the outer insulating layer to expose the conductive cores of overlapping conductive strands. A conductive material such as solder or conductive epoxy may be applied to the exposed portions of the conductive cores to electrically and mechanically connect the overlapping conductive strands.

An apparatus is disclosed for transferring a pattern of a composition containing particles of an electrically conductive material and a thermally activated adhesive from a surface of a flexible web to a surface of a substrate. The apparatus comprises: respective drive mechanisms for advancing the web and the substrate to a nip through which the web and the substrate pass at the same time and where a pressure roller acts to press the surfaces of the web and the substrate against one another, a heating station for heating at least one of the web and the substrate prior to, or during, passage through the nip, to a temperature at which the adhesive in the composition is activated, a cooling station for cooling the web after passage through the nip, and a separating device for peeling the web away from the substrate after passage through the cooling station, to leave the pattern of composition adhered to the surface of the substrate.

A method is disclosed for applying an electrical conductor to an electrically insulating substrate, which comprises providing a flexible membrane with a pattern of groove formed on a first surface thereof, and loading the grooves with a composition comprising conductive particles. The composition is, or may be made, electrically conductive. Once the membrane is loaded, the grooved first surface of the membrane is brought into contact with a front or/and back of the substrate. A pressure is then applied between the substrate and the membrane(s) so that the composition loaded to the grooves adheres to the substrate. The membrane(s) and the substrate are separated and the composition in the groove is left on the surface of the electrically insulating substrate. The electrically conductive particles in the composition are then sintered to form a pattern of electrical conductors on the substrate, the pattern corresponding to the pattern formed in the membrane(s).

A method for manufacturing a flexible circuit board is provided. The method for manufacturing a flexible circuit board includes the following steps: providing a carrier substrate, forming a flexible substrate on the carrier substrate, and forming a plurality of circuit strings on the flexible substrate. A flexible circuit board manufactured by the above method is also provided.

A method is disclosed for applying an electrical conductor to a solar cell, which comprises providing a flexible membrane with a pattern of groove formed on a first surface thereof, and loading the grooves with a composition comprising conductive particles. The composition is, or may be made, electrically conductive. Once the membrane is loaded, the grooved first surface of the membrane is brought into contact with a front or/and back of a solar cell. A pressure is then applied between the solar cell and the membrane(s) so that the composition loaded to the grooves adheres to the solar cell. The membrane(s) and the solar cell are separated and the composition in the groove is left on the solar cell surface. The electrically conductive particles in the composition are then sintered or otherwise fused to form a pattern of electrical conductor on the solar cell, the pattern corresponding to the pattern formed in the membrane(s).

A method is disclosed for applying an electrical conductor to an electrically insulating substrate, which comprises providing a flexible membrane with a pattern of groove formed on a first surface thereof, and loading the grooves with a composition comprising conductive particles. The composition is, or may be made, electrically conductive. Once the membrane is loaded, the grooved first surface of the membrane is brought into contact with a front or/and back of the substrate. A pressure is then applied between the substrate and the membrane(s) so that the composition loaded to the grooves adheres to the substrate. The membrane(s) and the substrate are separated and the composition in the groove is left on the surface of the electrically insulating substrate. The electrically conductive particles in the composition are then sintered to form a pattern of electrical conductors on the substrate, the pattern corresponding to the pattern formed in the membrane(s).