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 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.

Aspects of the invention include receiving a printed circuit board (PCB) having one or more of mounting pads thereon, determining a stencil for applying a solder paste to the one or more mounting pads, the stencil having a smallest aperture for a component requiring a standoff, determining a maximum threshold size for standoff particles based on the smallest aperture, determining a first concentration of the standoff particles based on the smallest aperture, determining a minimum threshold size for standoff particles to create the standoff for the component, determining a second concentration of the standoff particles to create a three-standoff seating plane for the component, introducing the standoff particles to the solder paste, the standoff particles in the solder paste having a concentration between the first concentration and the second concentration, and a size between the maximum threshold size and the minimum threshold size.

A low melting-point bonding member includes a low melting-point alloy containing Bi: 46 mass % or more and 72 mass % or less, In: 26 mass % or more and 54 mass % or less, and Sn: 2 mass % or less when a total amount of Bi, In, and Sn is 100 mass % and having a melting point of 86 to 111° C. A method for producing a low melting-point bonding member, including a plating step of performing a plating process including at least Bi plating and In plating and forming, on an object to be plated, a plating layer containing Bi: 46 mass % or more and 72 mass % or less, In: 26 mass % or more and 54 mass % or less, and Sn: 2 mass % or less when a total amount of Bi, In, and Sn is 100 mass %.

A solder product 20 includes: a lead-free solder part 21 containing tin as a main component and a metal element other than lead as a secondary component; and a carboxylic acid having 10 to 20 carbons, the carboxylic acid being mainly distributed over the surface of the solder product 20 to form a surface layer 22. The carboxylic acid is preferably a fatty acid having 12 to 16 carbons, and more preferably a palmitic acid.

A surface mounted technology (SMT) process prediction tool for intelligent decision making on PCB quality is disclosed. A data fusion tool automatically reads size parameters and component information on design conditions of a printed board to be assembled from a database and creates a design condition list for different components for a software execution layer; a printing parameter decision-making toolkit and a soldering parameter decision-making toolkit in the software execution layer perform comparisons on printing and soldering data according to design conditions of components on the printed board to be assembled, perform automatic decision making on printing and soldering parameters with a multi-objective optimization algorithm and a deep learning algorithm, predict printing quality and soldering quality, and send decided printing and soldering process parameters and corresponding predicted quality results to a human-computer interaction toolkit, to visually display the printing and soldering process parameters and the predicted quality values.

Implementations of the disclosure are directed to a lead-free mixed solder powder paste suitable for low temperature to middle temperature soldering applications. The lead-free solder paste may consist of: an amount of a first solder alloy powder between 44 wt % and 83 wt %, the first solder alloy powder comprising Sn; an amount of a second solder alloy powder between 5 wt % to 44 wt %, the second alloy powder comprising Sn, where the first solder alloy powder has a liquidus temperature lower than a solidus temperature of the second solder alloy powder; and a remainder of flux. The solder paste may be used for reflow at a peak temperature below the solidus temperature of the higher solidus temperature solder powder but above the melting temperature of the lower solidus temperature one.

Invention compositions are a replacement for high melting temperature solder pastes and preforms in high operating temperature and step-soldering applications. In the use of the invention, a mixture of metallic powders reacts below 350 degrees C. to form a dense metallic joint that does not remelt at the original process temperature.

An electronic control device includes: a circuit board; an electronic component; and a bonding portion bonding the circuit board and the electronic component to each other. The bonding portion contains Sn as a main component, Bi and Sb in a total content ratio of 3 wt % or more, and Ag in a content of 3 to 3.9 wt %, with no In.

A solder alloy is provided which can withstand the severe characteristics of a temperature cycle between a low temperature of −40° C. and a high temperature of 125° C., withstand an external force applied due to, for example, riding on a curb or collision with a vehicle ahead for a long period of time, and can suppress change in viscosity of a solder paste over time. In addition, a solder paste, a solder ball, and a solder preform in which the solder alloy is used; a solder joint formed through the use thereof; and an on-board electronic circuit, an ECU electronic circuit, an on-board electronic circuit device, and an ECU electronic circuit device which include this solder joint are provided. The solder alloy contains, by mass %, 1% to 4% of Ag, 0.5% to 1.0% of Cu, 1.5% to 5.5% of Bi, 1.0% to 5.3% of Sb (or greater than 5.5% and less than or equal to 7.0% of Bi and 2.0% to 5.3% of Sb), 0.01% to 0.2% of Ni, 0.0040% to 0.0250% of As, and a balance of Sn.