A circuit board includes a board including a first surface and a second surface opposing the first surface, where the board includes at least one conductive layer and at least insulating layer, a plurality of electronic elements disposed on the first surface of the board, and a plurality of resistive pads disposed on the second surface of the board and electrically connected to at least one selected from the electronic elements. The resistive pads have a resistance of zero ohm.

A flexible printed circuit and a manufacturing method thereof, an electronic device module and an electronic device are provided. The flexible printed circuit includes a main sub-circuit board and a bridge sub-circuit board; the main sub-circuit board includes a first substrate, and a first bridge end, a second bridge end, a first wiring portion, and a second wiring portion on the first substrate, the first wiring portion and the second wiring portion are spaced apart from each other and are electrically connected to the first bridge end and the second bridge end, respectively; the bridge sub-circuit board includes a second substrate, and a third bridge end, a fourth bridge end, and a third wiring portion for a first functional wiring line on the second substrate, the third bridge end and the fourth bridge end are electrically connected by the third wiring portion, the first substrate and the second substrate are not in direct contact, and the bridge sub-circuit board is configured to be mounted on the main sub-circuit board by electrically connecting the third bridge end and the fourth bridge end to the first bridge end and the second bridge end, respectively. The wiring layout of the flexible printed circuit is simple and is easy to be manufactured.

A resin flux solder paste includes a solder powder, and a flux, in which the flux contains at least an epoxy resin, a curing agent, a curing accelerator, and an activator, the epoxy resin contains 10% to 90% by weight of one or more of a biphenyl aralkyl type epoxy resin, a naphthalene type epoxy resin, and a dicyclopentadiene type epoxy resin, having an epoxy equivalent of 200 to 400, with respect to a total amount of the epoxy resin, and the curing agent contains 30% to 95% by weight of a biphenyl aralkyl phenol resin having a hydroxyl group equivalent of 150 to 350 with respect to a total amount of the curing agent, and 5% to 70% by weight of a phenol novolac resin having an allyl group having a hydroxyl group equivalent of 100 to 200 with respect to the total amount of the curing agent.

A solder alloy has an alloy composition consisting of, in mass %, Ag: from 3.2 to 3.8%, Cu: from 0.6 to 0.8%, Ni: from 0.01 to 0.2%, Sb: from 2 to 5.5%, Bi: from 1.5 to 5.5%, Co: from 0.001 to 0.1%, Ge: from 0.001 to 0.1%, and optionally at least one of Mg, Ti, Cr, Mn, Fe, Ga, Zr, Nb, Pd, Pt, Au, La and Ce: 0.1% or less in total, with the balance being Sn. The alloy composition satisfies the following relationship (1): 2.93≤{(Ge/Sn)+(Bi/Ge)}×(Bi/Sn) (1). In the relationship (1), each of Sn, Ge, and Bi represents the content (mass %) in the alloy composition.

A lead-free, antimony-free tin solder which is reliable at high temperatures and comprises from 3.5 to 4.5 wt.% of silver, 2.5 to 4 wt.% of bismuth, 0.3 to 0.8 wt.% of copper, 0.03 to 1 wt.% nickel, 0.005 to 1 wt.% germanium, and a balance of tin, together with any unavoidable impurities.

A wiring board includes: a first insulating layer; a first pad region provided above the first insulating layer and having a first connection pad; a second insulating layer provided above the first connection pad and having a first opening to expose the first connection pad; a second pad region provided above the second insulating layer and having a second connection pad electrically connected to the first connection pad; and a third insulating layer provided above the second connection pad, and having a second opening to exposes the first and second connection pads. The first connection pad region is smaller than the second connection pad region.

A metal composition that includes a first metal; and a second metal containing a first transition metal element added to a first alloy having a melting point higher than a melting point of the first metal, and the second metal is an alloy capable of producing an intermetallic compound with the first metal.

An electronic device having at least one circuit board. The circuit board has a predetermined pattern of solder bumps facilitating a ground connection with a first enclosure member and/or a second enclosure member. The at least one circuit board is sandwiched between the first and second enclosure members, each of the first and second enclosure members has a surface facing the circuit board and the surface facing the circuit board has a bead extending therefrom contacting the predetermined pattern of solder bumps to complete the ground connection.

The present disclosure is directed to a hybrid conductive ink including: silver nanoparticles and eutectic low melting point alloy particles, wherein a weight ratio of the eutectic low melting point alloy particles and the silver nanoparticles ranges from 1:20 to 1:5. Also provided herein are methods of forming an interconnect including a) depositing a hybrid conductive ink on a conductive element positioned on a substrate, wherein the hybrid conductive ink comprises silver nanoparticles and eutectic low melting point alloy particles, the eutectic low melting point alloy particles and the silver nanoparticles being in a weight ratio from about 1:20 to about 1:5; b) placing an electronic component onto the hybrid conductive ink; c) heating the substrate, conductive element, hybrid conductive ink and electronic component to a temperature sufficient i) to anneal the silver nanoparticles in the hybrid conductive ink and ii) to melt the low melting point eutectic alloy particles, wherein the melted low melting point eutectic alloy flows to occupy spaces between the annealed silver nanoparticles, d) allowing the melted low melting point eutectic alloy of the hybrid conductive ink to harden and fuse to the electronic component and the conductive element, thereby forming an interconnect. Electrical circuits including conductive traces and, optionally, interconnects formed with the hybrid conductive ink are also provided.

An object of the present invention is to provide an Sn—Bi—Cu—Ni solder alloy or the like which has a low melting point, excellent ductility, and high tensile strength, and in which if soldering is performed on a Cu electrode subjected to electroless Ni plating treatment, a solder joint formed through this soldering exhibits high shear strength. In addition, another object of the present invention is to provide an Sn—Bi—Cu—Ni solder alloy in which a solder joint formed through soldering exhibits high shear strength even for a Cu electrode which has not been subjected to plating treatment. Furthermore, still another object of the present invention is to provide, in addition to the above-described objects, a solder alloy or the like of which yellowish discoloration can be suppressed and in which change in viscosity of a solder paste over time can be suppressed. The solder alloy has an alloy composition consisting of, by mass %, 31% to 59% of Bi, 0.3% to 1.0% of Cu, 0.01% to 0.06% of Ni, 0.0040% to 0.025% of As, and a balance of Sn.