Provided is a lead-free solder alloy that has excellent tensile strength and ductility, does not deform after heat cycles, and does not crack. The In and Bi content are optimized and the Sb and Ni content are adjusted. As a result, this solder alloy has an alloy composition including, by mass, 1.0 to 7.0% of In, 1.5 to 5.5% of Bi, 1.0 to 4.0% of Ag, 0.01 to 0.2% of Ni, and 0.01 to 0.15% of Sb, with the remainder made up by Sn.

An amplifier device includes a substrate, a composite packaged amplifier having a bottom plate and an output plate, a first amplifier and a second amplifier provided on the bottom plate, a combining node that combines an output of the first amplifier with an output of the second amplifier, an output matching circuits provided on the bottom plate, that has a first transmission line provided between the first amplifier and the combining node, and a second transmission line provided between the combining node and the second amplifier, a third transmission line having one transmission line on which the output plate is mounted and other transmission line that connects the one transmission line to the external port, and wirings connecting to one terminal of the output plate and the combining node. A length of the output plate and the other transmission line is equal or less than π/4 radian for a signal.

A method for step-soldering includes applying a first solder alloy having a melting point in a temperature range from 160 to 210° C. to a jointed portion of a first electronic component and a substrate, and heating them in the temperature range from 160 to 210° C., and applying a second solder alloy having the melting point in a temperature range lower than 160° C. to a joint portion of a second electronic component and the substrate, and heating them in the temperature range lower than 160° C. The first solder alloy consists of 13-22 mass % of In, 0.5-2.8 mass % of Ag, 0.5-5.0 mass % of Bi, 0.002-0.05 mass % of Ni and a balance Sn.

A composite wiring substrate includes a first wiring substrate including a first connection terminal, a second wiring substrate including a second connection terminal facing the first connection terminal, and a joint material joining the first connection terminal and the second connection terminal. The first outline of the first connection terminal is inside the second outline of the second connection terminal in a plan view. The joint material includes a first portion formed of an intermetallic alloy of copper and tin, and contacting each of the first connection terminal and the second connection terminal, and a second portion formed of an alloy of tin and bismuth, and including a portion between the first outline and the second outline in the plan view. The second portion contains the bismuth at a higher concentration than in the eutectic composition of a tin-bismuth alloy, and is separated from the second connection terminal.

A bonding structure includes a first layer of first alloy component disposed on a substrate and a first layer of a second alloy component disposed on the first alloy component. The second alloy component has a lower melting temperature than the first alloy component. A second layer of the first alloy component is disposed on the first layer of the second alloy component and a second layer of the second alloy component is disposed on the second layer of the first alloy component.

A component mounting method includes an application step of applying a specific solder paste including Sn and a metal other than Sn to a board; a disposition step of positioning and disposing an upper surface reference type component having a positioning reference on an upper surface with respect to one or more reference points on the board; and a reflow step of reflow-soldering the component by heating the board, in which in the specific solder paste, at least a part of the Sn is melted, and molten Sn and the metal other than Sn form an intermetallic compound in the reflow step, thereby fixing the upper surface reference type component to the board.

A heat transfer member-equipped substrate includes a heat transfer member installed in a through hole of a substrate; a heat generating component; and a solder portion soldering the heat generating component to the heat transfer member, a nickel base plating formed on the heat transfer member, and the solder portion bonded to the nickel base plating where a gold plating that suppresses oxidization of the nickel base plating is blended into the solder portion. The heat transfer member includes a first and a second heat transfer portion bonded to each other, the first heat transfer portion made of a first metal, the second heat transfer portion made of a second metal formed on at least a portion of a surface of the second heat transfer portion, and the second heat transfer portion being a plate shape that protrudes from a circumference of the first heat transfer portion.

A magnetic-field melting solder that melts by the action of an AC magnetic field is provided. The magnetic-field melting solder includes solder material; and magnetic material composing of ferrite or Ni, a proportion of the magnetic material to the entire magnetic-field melting solder being 0.005% to 5% by weight. A joining method using the magnetic-field melting solder includes providing the magnetic-field melting solder between an electrode on a substrate and an electrode of an electronic component, and joining together the electrode on the substrate and the electrode of the electronic component by generating an AC magnetic field around the substrate and thereby melting the magnetic-field melting solder.

Flexible electrical devices comprising electrode layers on softening polymers and methods of manufacturing such devices, including lift-off processes for forming electrodes on softening polymers, processes for forming devices with a patterned double softening polymer layer, and solder reflow processes for forming electrical contacts on softening polymers.

A composite wiring substrate includes a first wiring substrate including a first connection terminal, a second wiring substrate including a second connection terminal facing the first connection terminal, and a joint material joining the first connection terminal and the second connection terminal. The first outline of the first connection terminal is inside the second outline of the second connection terminal in a plan view. The joint material includes a first portion formed of an intermetallic alloy of copper and tin, and contacting each of the first connection terminal and the second connection terminal, and a second portion formed of an alloy of tin and bismuth, and including a portion between the first outline and the second outline in the plan view. The second portion contains the bismuth at a higher concentration than in the eutectic composition of a tin-bismuth alloy, and is separated from the second connection terminal.