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.

Indium-tin-silver alloys suitable for use as a lead free solder are described herein. The alloys may comprise primarily indium or comprise primarily tin. The alloys may further include copper, nickel, and iron or copper, antimony, and zinc. The composition can be used to solder an electrical connector to an electrical contact surface on a glass component. Methods of forming the alloys are also described herein.

The manufacturing method includes (a) preparing first printed circuit board and second printed circuit board, the first printed circuit board being provided with a plurality of first terminals, the second printed circuit board being provided with a plurality of second terminals, and the first terminals or the second terminals being coated with solders; and (b) connecting the first terminals and the second terminals, respectively, via respective solders by performing thermocompression on connecting portions of the first printed circuit board and the second printed circuit board. Each second terminal includes a first end portion and a second end portion in a long axis direction, and in the step (b), pressure is applied to each second terminal such that the height of each of the first end portion and second end portion is larger than the height in another portion of the second terminal.

A solder composition for use in solder joints of printed circuit boards (PCBs), including a compound layer comprising an alloy of bismuth and tin; and a graphene coating positioned on the compound layer.

An electrical device, comprising a softening polymer layer, an electrode layer on a surface of the softening polymer layer and a cover polymer layer on the surface of the softening polymer layer. An opening in the polymer cover layer is filled with a reflowed solder, one end of the reflowed solder, located inside the opening, contacts a contact pad site portion of the electrode layer, and another end of the reflowed solder contacts an electrical connector electrode of the device.

A sheet-shaped solder that is not susceptible to electromigration, and a solder joint part and semiconductor device using the same are provided. A pressed sheet-shaped solder containing a solder alloy containing Sn as a primary component, an additional element, and an incidental impurity is provided. A pressed surface of the sheet-shaped solder is a surface perpendicular to a main surface of the sheet-shaped solder, and c-axes of Sn crystals are aligned in a direction perpendicular to a thickness direction of the sheet-shaped solder. Moreover, a solder joint part including a semiconductor element, and an electrically conductive connection member, and a solder joining layer being the above sheet-shaped solder melted between the semiconductor element and the electrically conductive connection member is provided.

Provided is a high-temperature lead-free solder alloy having excellent tensile strength and elongation in a high-temperature environment of 250° C. In order to make the structure of an Sn—Sb—Ag—Cu solder alloy finer and cause stress applied to the solder alloy to disperse, at least one material selected from the group consisting of, in mass %, 0.003 to 1.0% of Al, 0.01 to 0.2% of Fe, and 0.005 to 0.4% of Ti is added to a solder alloy containing 35 to 40% of Sb, 8 to 25% of Ag, and 5 to 10% of Cu, with the remainder made up by Sn.

A mounting structure includes a bonding material (106) that bonds second electrodes (104) of a circuit board (105) and bumps (103) of a semiconductor package (101), the bonding material (106) being surrounded by a first reinforcing resin (107). Moreover, a portion between the outer periphery of the semiconductor package (101) and the circuit board (105) is covered with a second reinforcing resin (108). Even if the bonding material (106) is a solder material having a lower melting point than a conventional bonding material, high drop resistance is obtained.

Solder material used in soldering of an Au electrode including Ni plating containing P includes Ag satisfying 0.3≦[Ag]≦4.0, Bi satisfying 0≦[Bi]≦1.0, and Cu satisfying 0<[Cu]≦1.2, where contents (mass %) of Ag, Bi, Cu and In in the solder material are denoted by [Ag], [Bi], [Cu], and [In], respectively. The solder material includes In in a range of 6.0≦[In]≦6.8 when [Cu] falls within a range of 0<[Cu]<0.5, In in a range of 5.2+(6−(1.55×[Cu]+4.428))≦[In]≦6.8 when [Cu] falls within a range of 0.5≦[Cu]≦1.0, In in a range of 5.2≦[In]≦6.8 when [Cu] falls within a range of 1.0<[Cu]≦1.2. A balance includes only not less than 87 mass % of Sn.

A solder alloy contains 0.5 mass % or more and 1.25 mass % or less of Sb, In which satisfies 5.5≦[In]≦5.50+1.06[Sb] in a case of 0.5≦[Sb]≦1.0; and 5.5≦[In]≦6.35+0.212[Sb] in a case of 1.0<[Sb]≦1.25 (in the expression, [Sb] indicates the Sb content percentage (mass %) and [In] indicates the In content percentage (mass %)), 0.5 mass % or more and 1.2 mass % or less of Cu, 0.1 mass % or more and 3.0 mass % or less of Bi, and 1.0 mass % or more and 4.0 mass % or less of Ag. The remainder is formed from Sn.