Abstract: A core material has a core 12; a solder layer 16 made of a (Sn—Bi)-based solder alloy provided on an outer side of the core 12; and a Sn layer 20 provided on an outer side of the solder layer 16. The core contains metal or a resin. When a concentration ratio of Bi contained in the solder layer 16 is a concentration ratio (%)=a measured value of Bi (% by mass)/a target Bi content (% by mass), or a concentration ratio (%)=an average value of measured values of Bi (% by mass)/a target Bi content (% by mass), the concentration ratio is 91.4% to 106.7%. The thickness of the Sn layer 20 is 0.215% or more and 36% or less of the thickness of the solder layer 16.

Abstract: A core material has a core 12; a solder layer 16 made of a (Sn—Bi)-based solder alloy provided on an outer side of the core 12; and a Sn layer 20 provided on an outer side of the solder layer 16. The core contains metal or a resin. When a concentration ratio of Bi contained in the solder layer 16 is a concentration ratio (%)=a measured value of Bi (% by mass)/a target Bi content (% by mass), or a concentration ratio (%)=an average value of measured values of Bi (% by mass)/a target Bi content (% by mass), the concentration ratio is 91.4% to 106.7%. The thickness of the Sn layer 20 is 0.215% or more and 36% or less of the thickness of the solder layer 16.

Abstract: A core material has a core; a solder layer provided outside the core and being a solder alloy containing Sn and at least any one element of Ag, Cu, Sb, Ni, Co, Ge, Ga, Fe, Al, In, Cd, Zn, Pb, Au, P, S, Si, Ti, Mg, Pd, and Pt; and a Sn layer provided outside the solder layer. The solder layer has a thickness of 1 ?m or more on one side. The Sn layer has a thickness of 0.1 ?m or more on one side. A thickness of the Sn layer is 0.215% or more and 36% or less of the thickness of the solder layer.

Abstract: A method includes applying a first flux onto an electrode provided on a substrate and placing a solder material on the electrode, heating the substrate to form a solder bump on the electrode, deforming the solder bump to provide a flat surface or a depressed portion on the solder bump, applying a second flux to the solder bump; placing a core material on the solder bump, the core material including a core portion and a solder layer that covers a surface of the core portion, and heating the substrate to join the core material to the electrode by the solder bump and the solder layer.

Abstract: A core material has a core 12; a solder layer 16 made of a (Sn—Bi)-based solder alloy provided on an outer side of the core 12; and a Sn layer 20 provided on an outer side of the solder layer 16. The core contains metal or a resin. When a concentration ratio of Bi contained in the solder layer 16 is a concentration ratio (%)=a measured value of Bi (% by mass)/a target Bi content (% by mass), or a concentration ratio (%)=an average value of measured values of Bi (% by mass)/a target Bi content (% by mass), the concentration ratio is 91.4% to 106.7%. The thickness of the Sn layer 20 is 0.215% or more and 36% or less of the thickness of the solder layer 16.

Abstract: A core material has a core; a solder layer provided outside the core and being a solder alloy containing Sn and at least any one element of Ag, Cu, Sb, Ni, Co, Ge, Ga, Fe, Al, In, Cd, Zn, Pb, Au, P, S, Si, Ti, Mg, Pd, and Pt; and a Sn layer provided outside the solder layer. The solder layer has a thickness of 1 ?m or more on one side. The Sn layer has a thickness of 0.1 ?m or more on one side. A thickness of the Sn layer is 0.215% or more and 36% or less of the thickness of the solder layer.

Abstract: A method includes applying a first flux onto an electrode provided on a substrate and placing a solder material on the electrode, heating the substrate to form a solder bump on the electrode, deforming the solder bump to provide a flat surface or a depressed portion on the solder bump, applying a second flux to the solder bump; placing a core material on the solder bump, the core material including a core portion and a solder layer that covers a surface of the core portion, and heating the substrate to join the core material to the electrode by the solder bump and the solder layer.

Abstract: An object of the present invention is to prevent “deteriorations,” such as oxidization and deformation of micro solder spheres during storage. The micro solder spheres are packed in a container 2 comprising an air permeable material. A deoxidizing and drying agent 3 to be disposed externally to the container 2 is provided. The container 2 and the deoxidizing and drying agent 3 are placed in a bag member 4 impermeable to air, and the bag member 4 is sealed in an air-tight condition. Before sealing, the bag member 4 may be air evacuated. A plurality of containers 2 may be held by a holding member 5 such that they are fixed in positions relative to each other.

Abstract: An object of the present invention is to prevent “deteriorations,” such as oxidization and deformation of micro solder spheres during storage. The micro solder spheres are packed in a container 2 comprising an air permeable material. A deoxidizing and drying agent 3 to be disposed externally to the container 2 is provided. The container 2 and the deoxidizing and drying agent 3 are placed in a bag member 4 impermeable to air, and the bag member 4 is sealed in an air-tight condition. Before sealing, the bag member 4 may be air evacuated. A plurality of containers 2 may be held by a holding member 5 such that they are fixed in positions relative to each other.

Abstract: A Sn—Ag—Cu based lead-free solder ball which does not undergo yellowing of its surface when formed into a solder bump on an electrode of an electronic part such as a BGA package. The solder ball has excellent wettability and does not form voids at the time of soldering, even when it has a minute diameter such as 0.04-0.5 mm. It has a composition comprising 1.0-4.0 mass % of Ag, 0.05-2.0 mass % of Cu, 0.0005-0.005 mass % of P, and a remainder of Sn.

Abstract: A lead-free solder includes 0.05-5 mass % of Ag, 0.01-0.5 mass % of Cu, at least one of P, Ge, Ga, Al, and Si in a total amount of 0.001-0.05 mass %, and a remainder of Sn. One or more of a transition element for improving resistance to heat cycles, a melting point lowering element such as Bi, In, or Zn, and an element for improving impact resistance such as Sb may be added.

Abstract: A Sn—Ag—Cu based lead-free solder ball which does not undergo yellowing of its surface when formed into a solder bump on an electrode of an electronic part such as a BGA package. The solder ball has excellent wettability and does not form voids at the time of soldering, even when it has a minute diameter such as 0.04-0.5 mm. It has a composition comprising 1.0-4.0 mass % of Ag, 0.05-2.0 mass % of Cu, 0.0005-0.005 mass % of P, and a remainder of Sn.

Abstract: A lead-free solder includes 0.05-5 mass % of Ag, 0.01-0.5 mass % of Cu, at least one of P, Ge, Ga, Al, and Si in a total amount of 0.001-0.05 mass %, and a remainder of Sn. One or more of a transition element for improving resistance to heat cycles, a melting point lowering element such as Bi, In, or Zn, and an element for improving impact resistance such as Sb may be added.