Abstract: Problem Precoating methods for previously adhering solder to areas to be soldered of a workpiece for an electronic part such as a printed circuit board, a chip part, or a wafer include the plating method, the hot leveling method, the solder paste method, the solder ball method, and the like. In these conventional precoating methods, solder did not uniformly adhere to areas to be soldered, solder did not completely adhere, and much equipment and time were required. The present invention provides a method which can perform precoating with uniform application and without the occurrence of defects using simple equipment and a workpiece to which solder is uniformly adhered. Means for Solving the Problem In the present invention, an excess amount of solder powder is dispersed atop an adhesive applied to a substrate, and then excess solder powder which is not adhered to the adhesive is removed.

Abstract: In the flux applying device, a control portion controls conveying rollers or the like so that thickness of flux applied to solder is controlled. The winding roller rotates so that the solder is conveyed at the conveying speed. The drawing-out roller applies any load (back tension) to the solder backward along the conveying direction of the solder when drawing out the solder. The solder is conveyed at the predetermined speed and dipped into the flux tank containing flux. The solder is pulled up from the flux tank at the conveying speed vertically. By pulling up the solder from the flux tank at the constant conveying speed vertically, the interfacial tension acts on the solder 9a and the flux, so that the flux having a uniform thickness according to the conveying speed remains on the surface and back surface of the solder.

Abstract: A solder-ball-supplying method, a solder-ball-supplying device and a solder-bump-forming method, which are flux-less and capable of being also applied to electrodes having a fine pitch. A substrate on which a resist with openings is positioned on electrode(s), which has a diameter of 10 through 30 ?m, of the substrate is prepared. Next, plural solder balls SBL each having a grain diameter of 1 through 10 ?m are shaken down to the opening(s) of the resist from a hopper and filled therein. Next, by sliding and moving a squeegee on an upper surface of the resist along X-Y direction, the solder balls SBL shaken down to the resist other than the openings are scrapped and removed and the solder balls SBL in the openings and around them are pushed into the openings by the squeegee.

Abstract: The present solder transfer sheet addresses the issue of providing a solder transfer sheet having both solder powder holding properties and sheet releasing properties and having excellent solder transfer properties. This solder transfer sheet is for soldering in a section to be soldered in a circuit substrate and has: a support base material; an adhesive layer provided on at least one surface of the support base material; and at least one solder layer including solder particles, provided upon the adhesive layer. The adhesive layer contains a side-chain crystalline polymer, exhibits viscosity by having fluidity at at least the melting point of the side-chain crystalline polymer, and decreases viscosity by crystalizing at temperatures less than the melting point of the side-chain crystalline polymer.

Abstract: An electrode for an energy storage device including a Zn layer or Zn alloy layer, a Ni layer, and a Sn layer or Sn alloy layer formed by plating on a connecting terminal part of a positive electrode composed of Al so that the resistance value at the contacting point is reduced and the voltage of the energy storage device can be effectively supplied without any drop. Accordingly, this electrode can be soldered to a Cu negative electrode, which is composed of metal that is different species from Al, through a Sn layer or a Sn alloy layer so that jointing strength of the Al positive electrode and the Cu negative electrode can be enhanced. The contacting area is increased in comparison with the conventional jointing by spot-welding or conventional fastening by a bolt so that the resistance value at the contacting point is reduced.

Abstract: A flux for a resin flux cored solder contains 30% or more by mass but 80% or less by mass rosin ester and 5% or more by mass but 15% or less by mass activator. The total content ratio of base materials including the rosin ester is preferably equal to or more than 85% by mass but equal to or less than 95% by mass.

Abstract: Zn layer 21 or Zn alloy layer, Ni layer 22, and Sn layer 23 or Sn alloy layer are formed on a connecting terminal part 10a of a positive electrode composed of Al by plating. Accordingly, this can solder Cu negative electrode, which is composed of metal that is different species from Al, through Sn layer 23 or Sn alloy layer so that jointing strength of the Al positive electrode and the Cu negative electrode can be enhanced. Further, since the contacting area is increased in comparison with the conventional jointing by the spot-welding or the conventional fastening by a bolt so that the resistance value at the contacting point is reduced, the voltage drop of the energy storage device by contact resistance can be reduced.

Abstract: A solder paste using a Sn—Ag base, Sn—Cu base, or similar alloy powder has a high melting point, so it causes thermal damage to electronic devices. Sn—Ag—In base lead-free solder alloys having a low melting temperature have been studied, but they are difficult to use because they cause much occurrence of chips standing up during reflow. The present invention forms a solder paste by separating a Sn—Ag—In base lead-free solder into first and second solder alloy powders for which the difference in their peak temperatures measured by differential thermal analysis is at least 10° C. and blends the mixed powders with a flux.

Abstract: To provide flux for flux cored solder that allows flux residue to have flexibility and can be used without depending on any soldering method. The flux for flux cored solder contains rosin, high molecular compound that prevents melt viscosity of the flux from being increased and allows a flux residue to have flexibility after heating by soldering, and halide that prevents the melt viscosity of the flux from being increased and by a combination of the high molecular compound that allows the flux residue to have flexibility after the heating by the soldering, allows the flux to cover a surface of solder melted during the heating by the soldering.

Abstract: A method of forming solder bumps on electrodes of a circuit board without producing bridging using a solder transfer sheet which does not require alignment includes superposing a circuit board and a solder transfer sheet having a solder layer adhered to at least one side of a supporting substrate, performing heating under pressure to a temperature lower than the solidus temperature of the solder to selectively perform solid phase diffusion bonding of the solder layer to electrodes, and peeling the transfer sheet from the circuit board. The solder layer is in the form of a continuous solder coating or in the form of a monoparticle layer of solder particles which are adhered to the supporting substrate by an adhesive layer.

Abstract: To increase a ground contact area in comparison with the conventional jointing by the spot-welding or the conventional fastening by a bolt so that the resistance value at the contacting point is reduced and the voltage of the energy storage device can be effectively supplied without any drop of the voltage. Zn layer 21 or Zn alloy layer, Ni layer 22, and Sn layer 23 or Sn alloy layer are formed on a connecting terminal part 10a of a positive electrode composed of Al by plating. Accordingly, this can solder Cu negative electrode, which is composed of metal that is different species from Al, through Sn layer 23 or Sn alloy layer so that jointing strength of the Al positive electrode and the Cu negative electrode can be enhanced.

Abstract: A method of forming solder bumps on electrodes of a circuit board without producing bridging using a solder transfer sheet which does not require alignment includes superposing a circuit board and a solder transfer sheet having a solder layer adhered to at least one side of a supporting substrate, performing heating under pressure to a temperature lower than the solidus temperature of the solder to selectively perform solid phase diffusion bonding of the solder layer to electrodes, and peeling the transfer sheet from the circuit board. The solder layer is in the form of a continuous solder coating or in the form of a monoparticle layer of solder particles which are adhered to the supporting substrate by an adhesive layer.

Abstract: A mixed mother alloy is prepared from a solder mixture comprising a pyrolyzable flux and high melting point metal particles, the mixed mother alloy is charged into a large amount of molten solder and stirred, and a billet is prepared. The billet can then be extruded, rolled, and punched to form a pellet or a washer, for example.

Abstract: A solder preform according to the present invention has a variation in the size of high melting point metal particles which is at most 20 micrometers when the metal particle diameter is 50 micrometers, and an alloy layer of the high melting point metal particles and the main component of solder is formed around the high melting point metal particles. In addition, no voids at all are present in the solder. An electronic component according to the present invention has a semiconductor element bonded to a substrate with the above-described solder preform and has excellent resistance to heat cycles.

Abstract: A mixed mother alloy is prepared from a solder mixture comprising a pyrolyzable flux and high melting point metal particles, the mixed mother alloy is charged into a large amount of molten solder and stirred, and a billet is prepared. The billet can then be extruded, rolled, and punched to form a pellet or a washer, for example.

Abstract: An electronic component having a semiconductor element bonded to a substrate with solder has a decreased bonding strength if there is not a suitable clearance between the semiconductor element and the substrate. Therefore, a solder preform having high melting point metal particles dispersed in solder has been used in the manufacture of electronic components. However, when an electronic component was manufactured using a conventional solder preform, there were cases in which the semiconductor element leaned or the bonding strength was not adequate. A solder preform according to the present invention has a variation in the size of high melting point metal particles which is at most 20 micrometers when the metal particle diameter is 50 micrometers, and an alloy layer of the high melting point metal particles and the main component of solder is formed around the high melting point metal particles. In addition, no voids at all are present in the solder.

Abstract: A mixed mother alloy is prepared from a solder mixture comprising a pyrolyzable flux and high melting point metal particles, the mixed mother alloy is charged into a large amount of molten solder and stirred, and a billet is prepared. The billet can then be extruded, rolled, and punched to form a pellet or a washer, for example.

Abstract: Problem Precoating methods for previously adhering solder to areas to be soldered of a workpiece for an electronic part such as a printed circuit board, a chip part, or a wafer include the plating method, the hot leveling method, the solder paste method, the solder ball method, and the like. In these conventional precoating methods, solder did not uniformly adhere to areas to be soldered, solder did not completely adhere, and much equipment and time were required. The present invention provides a method which can perform precoating with uniform application and without the occurrence of defects using simple equipment and a workpiece to which solder is uniformly adhered. Means for Solving the Problem In the present invention, an excess amount of solder powder is dispersed atop an adhesive applied to a substrate, and then excess solder powder which is not adhered to the adhesive is removed.

Abstract: A solder ball assembly for use in the formation of solder bumps on electrodes of a substrate for electronic components includes a heat-resisting sheet having a plurality of holes formed therein. Each hole has a solder ball disposed therein. The sheet includes an adherent layer exposed to the interior of each hole on the wall and/or bottom of the hole such that the adherent layer contacts and holds the solder balls in the holes. Solder bumps are formed by positioning the assembly on a substrate such that the solder balls held in the holes come into contact with the electrodes of the substrate. The assembly and the substrate are heated together to melt the solder balls in the holes. After solidification of the solder, the heat-resisting sheet of the assembly is removed from the substrate, leaving a solder bump on each electrode.

Abstract: A solder ball assembly includes a mask having first and second sides and a plurality of holes formed therein. Each hole has a first end opening onto the first side of the mask and a second end. A plurality of solder balls are disposed in the holes, and a fixing agent secures the solder balls in the holes. A protective sheet may be attached to one or both sides of the mask to cover the ends of the holes.