Provided are a Sn—Bi—In-based low melting-point joining member used in a Pb-free electroconductive joining method in mounting a semiconductor component, and is usable for low-temperature joining, and a manufacturing method therefor.

A Sn—Bi—In-based low melting-point joining member, including a Sn—Bi—In alloy that has a composition within a range represented by a quadrangle in a Sn—Bi—In ternary phase diagram, a first quadrangle having four vertices including: Point 1 (1, 69, 30), Point 2 (26, 52, 22), Point 3 (40, 10, 50), and Point 4 (1, 25, 74), where Point (x, y, z) is defined as a point of x mass % Sn, y mass % Bi and z mass % In, and that also has a melting point of 60 to 110° C. As well as a method for producing a Sn—Bi—In-based low melting-point joining member, including a plating step of forming a plated laminate on an object to be plated, the plated laminate including a laminated plating layer obtained by performing Sn plating, Bi plating, and In plating respectively such that the laminated plating layer has a composition within the range represented by the first quadrangle.

Some implementations of the disclosure describe a solder paste consisting essentially of: 10 wt % to 90 wt % of a first solder alloy powder, the first solder alloy powder consisting of a Sn—Sb alloy, a Sn—Ag—Cu—Sb alloy, a Sn—Ag—Cu—Sb—In alloy, a Sn—Ag—Cu—Sb—Bi alloy, or Sn—Ag—Cu—Sb—Bi—In alloy; 10 wt % to 90 wt % of a second solder alloy powder, the second solder alloy powder consisting of an Sn—Ag—Cu alloy or Sn—Ag—Cu—Bi alloy, and the second solder alloy powder having a lower solidus temperature than the first solder alloy powder; and flux.

Some implementations of the disclosure describe a solder paste consisting essentially of: 10 wt % to 90 wt % of a first solder alloy powder, the first solder alloy powder consisting of a Sn—Sb alloy, a Sn—Ag—Cu—Sb alloy, a Sn—Ag—Cu—Sb—In alloy, a Sn—Ag—Cu—Sb—Bi alloy, or Sn—Ag—Cu—Sb—Bi—In alloy; 10 wt % to 90 wt % of a second solder alloy powder, the second solder alloy powder consisting of an Sn—Ag—Cu alloy or Sn—Ag—Cu—Bi alloy, and the second solder alloy powder having a lower solidus temperature than the first solder alloy powder; and flux.

Some implementations of the disclosure are directed to low melting temperature (e.g., liquidus temperature below 210° C.) SnIn solder alloys. A SnIn solder alloy may consist of: 8 to 20 wt % In; greater than 0 wt % to 4 wt % Ag; optionally, one or more of greater than 0 wt % to 5 wt % Sb, greater than 0 wt % to 3 wt % Cu, greater than 0 wt % to 2.5 wt % Zn, greater than 0 wt % to 1.5 wt % Ni, greater than 0 wt % to 1.5 wt % Co, greater than 0 wt % to 1.5 wt % Ge, greater than 0 wt % to 1.5 wt % P, and greater than 0 wt % to 1.5 wt % Mn; and a remainder of Sn.

Some implementations of the disclosure are directed to low melting temperature (e.g., liquidus temperature below 210° C.) SnIn solder alloys. A SnIn solder alloy may consist of: 8 to 20 wt % In; greater than 0 wt % to 4 wt % Ag; optionally, one or more of greater than 0 wt % to 5 wt % Sb, greater than 0 wt % to 3 wt % Cu, greater than 0 wt % to 2.5 wt % Zn, greater than 0 wt % to 1.5 wt % Ni, greater than 0 wt % to 1.5 wt % Co, greater than 0 wt % to 1.5 wt % Ge, greater than 0 wt % to 1.5 wt % P, and greater than 0 wt % to 1.5 wt % Mn; and a remainder of Sn.

A solder alloy is provided which suppresses the change in a solder paste over time, decreases the temperature difference between the liquidus-line temperature and the solidus temperature, and exhibits a high reliability. The solder alloy has an alloy constitution composed of: 10 ppm by mass or more and less than 25 ppm by mass of As; at least one selected from the group consisting of 0 ppm by mass to 10000 ppm by mass of Bi and 0 ppm by mass to 5100 ppm by mass of Pb; more than 0 ppm by mass and no more than 3000 ppm by mass of Sb; and a remaining amount of Sn; and satisfies both the formula (1) and the formula (2).
300≤3As+Sb+Bi+Pb  (1)
0.1≤{(3As+Sb)/(Bi+Pb)}×100≤200  (2) In the formula (1) and the formula (2), As, Sb, Bi, and Pb each represents an amount thereof (ppm by mass) in the alloy constitution.

A solder alloy comprises Ag: 3.1 to 4.0% by mass, Cu: 0.6 to 0.8% by mass, Bi: 1.5 to 5.5% by mass, Sb: 1.0 to 6.0% by mass, Co: 0.001 to 0.030% by mass, Fe: 0.02 to 0.05% by mass, and a balance Sn.

A solder alloy comprises Ag: 3.1 to 4.0% by mass, Cu: 0.6 to 0.8% by mass, Bi: 1.5 to 5.5% by mass, Sb: 1.0 to 6.0% by mass, Co: 0.001 to 0.030% by mass, Fe: 0.02 to 0.05% by mass, and a balance Sn.

Provided are a solder alloy which has excellent temperature cycle characteristics and in which yellowish discoloration is suppressed, excellent wettability is maintained, and an increase in viscosity of a solder paste over time can be suppressed, and a solder paste, a solder ball, and a solder joint in which the solder alloy is used. The solder alloy consists of, by mass %, 1.0% to 5.0% of Ag, 0.5% to 3.0% of Cu, 0.5% to 7.0% of Sb, 0.0040% to 0.025% of As, and a balance of Sn.

A flux containing an organic acid, an acrylic resin, a rosin, a thixotropic agent, and a solvent, but not containing water is adopted. In this flux, the organic acid includes 1,2,3-propanetricarboxylic acid, and the content of the 1,2,3-propanetricarboxylic acid is 0.1% by mass or more and 15% by mass or less with respect to the total amount of the entire flux. According to this flux, the wettability of solder can be enhanced, temperature cycle reliability is excellent, and scattering due to heating during reflow can be suppressed.