A solder alloy that contains 0.005 mass % or more and 0.1 mass % or less of Mn, 0.001 mass % or more and 0.1 mass % or less of Ge, and a balance of Sn. A plurality of Ge oxides is distributed on an outermost surface side of an oxide film including Sn oxide, Mn oxide and Ge oxide by adding 0.005 mass % or more and 0.1 mass % or less of Mn, 0.001 mass % or more and 0.1 mass % or less of Ge to the solder alloy having a principal ingredient of Sn, so that it is possible to obtain the discolor-inhibiting effect even under the high-temperature and high-humidity environment.

A solder alloy that contains 0.005 mass % or more and 0.1 mass % or less of Mn, 0.001 mass % or more and 0.1 mass % or less of Ge, and a balance of Sn. A plurality of Ge oxides is distributed on an outermost surface side of an oxide film including Sn oxide, Mn oxide and Ge oxide by adding 0.005 mass % or more and 0.1 mass % or less of Mn, 0.001 mass % or more and 0.1 mass % or less of Ge to the solder alloy having a principal ingredient of Sn, so that it is possible to obtain the discolor-inhibiting effect even under the high-temperature and high-humidity environment.

As electronic equipment has become smaller in size, printed circuit boards which cannot be subjected to cleaning have been developed, and a no-clean lead-free solder paste is becoming necessary. In order for a solder paste not to require cleaning, it is necessary that the color of the residue be transparent and that the residue be non-tacky. A maleated rosin, which is a rosin suited for no-clean paste, has a high acid value so it is not suitable for a flux for lead-free solder. As a means of suppressing a reaction between a flux containing a maleated rosin and a Sn—Ag—Cu based solder alloy powder, a Sn—Ag—Cu—Sb based solder alloy powder is used which adds 1-8 mass % of Sb to a Sn—Ag—Cu based solder alloy. As a result, it is possible to provide a solder paste which has the excellent effect that the solder paste does not easily undergo changes over time and has a long pot life.

As electronic equipment has become smaller in size, printed circuit boards which cannot be subjected to cleaning have been developed, and a no-clean lead-free solder paste is becoming necessary. In order for a solder paste not to require cleaning, it is necessary that the color of the residue be transparent and that the residue be non-tacky. A maleated rosin, which is a rosin suited for no-clean paste, has a high acid value so it is not suitable for a flux for lead-free solder. As a means of suppressing a reaction between a flux containing a maleated rosin and a Sn—Ag—Cu based solder alloy powder, a Sn—Ag—Cu—Sb based solder alloy powder is used which adds 1-8 mass % of Sb to a Sn—Ag—Cu based solder alloy. As a result, it is possible to provide a solder paste which has the excellent effect that the solder paste does not easily undergo changes over time and has a long pot life.

To provide a Ni ball having a low α dose and high sphericity even when it contains impurity elements other than Ni in certain amounts. The Ni ball contains an element U, a content thereof being 5 ppb or less, and an element Th, a content thereof being 5 ppb or less, wherein a purity of the Ni ball is 99.9% or more but 99.995% or less, an α dose thereof is 0.0200 cph/cm.sup.2 or less, a content of either Pb or Bi, or a total content of both Pb and Bi is 1 ppm or more, and a sphericity thereof is 0.90 or more, in order to prevent any software errors and reduce connection failure.

To provide a Ni ball having a low α dose and high sphericity even when it contains impurity elements other than Ni in certain amounts. The Ni ball contains an element U, a content thereof being 5 ppb or less, and an element Th, a content thereof being 5 ppb or less, wherein a purity of the Ni ball is 99.9% or more but 99.995% or less, an α dose thereof is 0.0200 cph/cm.sup.2 or less, a content of either Pb or Bi, or a total content of both Pb and Bi is 1 ppm or more, and a sphericity thereof is 0.90 or more, in order to prevent any software errors and reduce connection failure.

A method for synthesizing a reagent complex includes a step of ball-milling a mixture that includes: a powder of a zero-valent element; a hydride molecule; and a nitrile ligand. The method produces a reagent complex having a formula Q.sup.0.X.sub.y.L.sub.z, where Q.sup.0 is the zero-valent element, X is the hydride molecule, and L is the nitrile ligand. A process for synthesizing nanoparticles composed of the zero-valent element includes a step of adding solvent to the reagent complex. Crystal texture of the nanoparticles is modulated by appropriate selection of the molar ratio nitrile ligand in the reagent complex.

Provided are a lead-free solder alloy which consists of Sb in an amount of more than 3.0% but 10% or less by mass, and the balance including Sn, and others.

Provided are a lead-free solder alloy which consists of Sb in an amount of more than 3.0% but 10% or less by mass, and the balance including Sn, and others.

In a lead-free solder bump, diffusion of Cu from intermetallic compound layers, which are respectively formed at joining interfaces with Cu electrodes is suppressed, so that the in metallic compound layers are not likely to disappear. Correspondingly, with the use of the intermetallic compound layers, Cu is not likely to diffuse from the Cu electrodes into the lead-free solder bump. Even when an electric current flows continuously between a first electronic member and a second electronic member through the lead-free solder bump, the occurrences of the electromigration phemenon and the thermomigration phenomenon are suppressed. Thus, the present invention provides a lead-free solder bump joining structure capable of suppressing the disconnection failure caused by the synergistic effect of the electromigration phenomenon and the thermomigration phenomenon.