Abstract: The invention relates to a method for forming bump electrodes on an electronic part such as a chip or a substrate. Conventional methods for forming bump electrode had a factor causing high cost, but with the invention, instead of solder balls, low cost solder wires are used, that is, solder wires are cut in a predetermined length, the cut solder wires are vacuum-attracted to the lower face of a pick up head and transferred onto a chip, then the solder pieces transferred are heated to melt, then cooled to solidify and results in forming bump electrodes of hemisphere shape.

Abstract: An electronic part is tacked to a circuit board, leads of the electronic part being made into contact with cream solder built up on the circuit board, and thereafter, the circuit board is heated up so as to melt the cream solder in order to solder the electronic part to the circuit board. In this procedure, the melting temperature of a hardener in the tacking bond, that is, the hardening temperature of the tacking bond, is higher than that of the cream solder, thereby making it possible to prevent hindrance to sinking of the lead terminal of the electronic part into the melted cream solder.

Abstract: A printed circuit board comprising a plurality of lands onto which a plurality of leads of an electronic component are soldered. These lands are arrayed in parallel one another. Each of these lands includes a narrow portion basically extending in a longitudinal direction thereof and having a predetermined constant width, and a wide portion protruding laterally from both edges of the narrow portion.