The present invention provides a solder material containing Sn or a Sn-containing alloy and 40 to 320 ppm by mass of A, the solder material including an As-enriched layer.

Some implementations of the disclosure relate to a lead-free solder paste with mixed solder powders that is particularly suitable for high temperature soldering applications involving multiple board-level reflow operations. In one implementation, the solder paste consists of 10 wt % to 90 wt % of a first solder alloy powder, the first solder alloy powder consisting of an SnSbCuAg solder alloy that has a wt % ratio of Sn:Sb of 0.75 to 1.1; 10 wt % to 90 wt % of a second solder alloy powder, the second solder alloy powder consisting of an Sn solder alloy including at least 80 wt % of Sn; and a remainder of flux.

A solder joint which is used in power devices and the like and which can withstand a high current density without developing electromigration is formed of a Sn—Ag—Bi—In based alloy. The solder joint is formed of a solder alloy consisting essentially of 2-4 mass % of Ag, 2-4 mass % of Bi, 2-5 mass % of In, and a remainder of Sn. The solder alloy may further contain at least one of Ni, Co, and Fe.

A solder joint which is used in power devices and the like and which can withstand a high current density without developing electromigration is formed of a Sn—Ag—Bi—In based alloy. The solder joint is formed of a solder alloy consisting essentially of 2-4 mass % of Ag, 2-4 mass % of Bi, 2-5 mass % of In, and a remainder of Sn. The solder alloy may further contain at least one of Ni, Co, and Fe.

A lead-free solder alloy may comprise tin, silver, copper, bismuth, cobalt, titanium, and antimony. The alloy may further comprise antimony, nickel, or both. The silver may be present in an amount from about 3.1% to 3.8% by weight of the solder. The copper may be present in an amount from about 0.5% to 0.8% by weight of the solder. The bismuth may be present in an amount from about 0.0% (or 1.5%) to about 3.2% by weight of the solder. The cobalt may be present in an amount from about 0.03% to about 1.0% (or 0.05%) by weight of the solder. The titanium may be present in an amount from about 0.005% to about 0.02% by weight of the solder. The antimony may be present in an amount between about 1.0% to about 3.0% by weight of the solder. The balance of the solder is tin.

A lead-free solder alloy may comprise tin, silver, copper, bismuth, cobalt, titanium, and antimony. The alloy may further comprise antimony, nickel, or both. The silver may be present in an amount from about 3.1% to 3.8% by weight of the solder. The copper may be present in an amount from about 0.5% to 0.8% by weight of the solder. The bismuth may be present in an amount from about 0.0% (or 1.5%) to about 3.2% by weight of the solder. The cobalt may be present in an amount from about 0.03% to about 1.0% (or 0.05%) by weight of the solder. The titanium may be present in an amount from about 0.005% to about 0.02% by weight of the solder. The antimony may be present in an amount between about 1.0% to about 3.0% by weight of the solder. The balance of the solder is tin.

A micro/nanoparticle-reinforced composite solder for low-temperature soldering and a preparation method thereof belong to the manufacturing field of lead-free low-temperature soldering solders. Micro/nanoparticle-reinforced tin-based alloy solder powder is formed by diffusely mixing micro/nano-sized Cu, Ag and Sb particles with a molten metal tin and atomizing the mixture, and then blended with low-melting-point SnBi-based alloy solder powder and a conventional flux to prepare a micro/nanoparticle-reinforced composite solder. In soldering at a temperature below 200° C., tin atoms in the molten micro/nanoparticle-reinforced tin-based alloy form an intermetallic compound on a soldering pan in preference to the low-melting-point SnBi-based alloy, and the micro/nanoparticles are dispersed in soldered joints to form a “separator effect”, which blocks atoms in the SnBi-based alloy from being precipitated and bonded with the soldering pan, thereby inhibiting the growth of a Bi-rich layer, and solving the problem of brittle and unreliable soldered joints in lead-free low-temperature soldering.

A micro/nanoparticle-reinforced composite solder for low-temperature soldering and a preparation method thereof belong to the manufacturing field of lead-free low-temperature soldering solders. Micro/nanoparticle-reinforced tin-based alloy solder powder is formed by diffusely mixing micro/nano-sized Cu, Ag and Sb particles with a molten metal tin and atomizing the mixture, and then blended with low-melting-point SnBi-based alloy solder powder and a conventional flux to prepare a micro/nanoparticle-reinforced composite solder. In soldering at a temperature below 200° C., tin atoms in the molten micro/nanoparticle-reinforced tin-based alloy form an intermetallic compound on a soldering pan in preference to the low-melting-point SnBi-based alloy, and the micro/nanoparticles are dispersed in soldered joints to form a “separator effect”, which blocks atoms in the SnBi-based alloy from being precipitated and bonded with the soldering pan, thereby inhibiting the growth of a Bi-rich layer, and solving the problem of brittle and unreliable soldered joints in lead-free low-temperature soldering.

A lead-free silver-free solder alloy may comprise tin, copper, bismuth, cobalt, and antimony. Alternatively, the alloy may comprise gallium in lieu of cobalt. The alloy may further comprise nickel, germanium, or both. The copper may be present in an amount from about 0.5% to 0.9% by weight of the solder. The bismuth may be present in an amount from about 1.0% to about 3.5% by weight of the solder. The cobalt may be present in an amount from about 0.02% to about 0.08% by weight of the solder. Where gallium is used in lieu of cobalt, the gallium may be present in an amount from about 0.2% to about 0.8% by weight of the solder. The antimony may be present in an amount between about 0.0% to about 0.09% by weight of the solder. The balance of the solder is tin.

A lead-free silver-free solder alloy may comprise tin, copper, bismuth, cobalt, and antimony. Alternatively, the alloy may comprise gallium in lieu of cobalt. The alloy may further comprise nickel, germanium, or both. The copper may be present in an amount from about 0.5% to 0.9% by weight of the solder. The bismuth may be present in an amount from about 1.0% to about 3.5% by weight of the solder. The cobalt may be present in an amount from about 0.02% to about 0.08% by weight of the solder. Where gallium is used in lieu of cobalt, the gallium may be present in an amount from about 0.2% to about 0.8% by weight of the solder. The antimony may be present in an amount between about 0.0% to about 0.09% by weight of the solder. The balance of the solder is tin.