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 microsphere of solder having a metallic core, in which the thickness of the solder coating of the microsphere is more than 20 microns, can be produced by a process comprising preparing a sheet having a plurality of hollows provided all over the sheet, placing a spherical grain of a metal together with at least one grain of solder in each of said hollows, the metallic grain having wettability for solder, then heating the grains in the hollow in the presence of a flux to coat the metallic grain with the solder, and recovering a spherical solder bead having a metallic core.