Abstract: This method controls a copper density in a dip solder bath holding a molten solder alloy containing at least copper as an essential composition thereof during a dip soldering step of one of a printed circuit board with a surfaced copper foil and a component part having a copper lead attached thereto. The method includes a step of introducing a replenished solder containing no copper at all or a copper content having a density lower than that of the molten solder in the bath prior to the supply of the replenished solder to the bath so that the copper density in the bath is controlled to a predetermined constant density or lower. The molten solder alloy in the bath contains tin, copper and nickel as the major compositions thereof, and the replenished solder contains nickel and balanced tin, for example. Alternatively, the molten solder alloy in the bath contains tin, copper, and silver as the major components thereof, and the replenished solder contains silver and balanced tin.

Abstract: To provide a solder jet machine with which a molten solder wave with stable height can be obtained. A satisfactory and stable molten solder wave is obtained by forming wall portions surrounding solder ejecting ports, which are arranged in a first, a second and a third ejecting-port rows on a solder wave forming plate, in such a manner that they are allowed to project upwardly, in addition, by forming groove portions, which are for introducing the ejected solder in such a direction as to be allowed to flow down, around the above-described solder ejecting ports, so that the molten solder ejected from the solder ejecting ports in the third row and the second row can flow down rapidly between adjacent solder ejecting ports in the first row without disturbing any wave of the molten solder ejected from the first row.

Abstract: This method controls a copper density in a dip solder bath holding a molten solder alloy containing at least copper as an essential composition thereof during a dip soldering step of one of a printed circuit board with a surfaced copper foil and a component part having a copper lead attached thereto. The method includes a step of introducing a replenished solder containing no copper at all or a copper content having a density lower than that of the molten solder in the bath prior to the supply of the replenished solder to the bath so that the copper density in the bath is controlled to a predetermined constant density or lower The molten solder alloy in the bath contains tin, copper and nickel as the major compositions thereof, and the replenished solder contains nickel and balanced tin, for example. Alternatively, the molten solder alloy in the bath contains tin, copper, and silver as the major components thereof and the replenished solder contains silver and balanced tin.

Abstract: To provide a jet solder feeding device enabling the prevention of poor wetting of a substrate and molten solder which may occur due to gas or air accumulated under the bottom surface of a substrate when the substrate is conveyed to the point where it is fed with molten solder. The jet solder feeding device is designed in such a manner that multiple ejecting ports are provided in more than one rows relative to the substrate-conveying direction and arranged at a second prescribed pitch in lines substantially along multiple inclined lines which are inclined to the substrate-conveying direction and arranged at a first prescribed pitch relative to the direction perpendicular to the substrate-conveying direction, the first prescribed pitch being set to be larger than the second prescribed pitch, so that a flow of molten solder passing through midway between groups of the ejecting ports is positively created.

Abstract: A soldering method aimed to obtain higher bonding strength than conventionally obtained ones. With the soldering method according to the present invention, a Cu mounting surface is soldered with a preliminary solder comprising Sn-Cu, and a component is finally soldered to this preliminarily soldered surface with a solder comprising Sn-Ag-Cu-Bi. Thus, higher bonding strength can be obtained not only in the interface between the preliminary solder surface and the solder for final soldering, but also in the interface between the mounting surface and the preliminary solder.

Abstract: A jet solder feeding device allowing the molten solder ejected from ejecting ports to be kept at a desired height in a stable manner. The molten solder is ejected and fed from multiple ejecting ports formed on a corrugated plate, each wall portion surrounding the multiple ejecting ports formed on the corrugated plate is projected upward by coining or extrusion. This configuration allows the molten solder introduced under the corrugated plate to be satisfactorily guided by the conically shaped wall portion which surrounds each ejecting port and projected upward. Thus the molten solder ejected from the ejecting ports can be kept at a desired height, and in addition, its state is satisfactorily maintained in a stable manner.