PURPOSE: To simplify a method for soldering, improve its accuracy and permit tight soldering by a method wherein a self-recoverable member is mounted on a circuit board, press-welding of a chip part is stopped during solving a solder bump, the chip member is elevated by the self-recoverable force of the member and soldering is done between electrodes of the chip part and with a wiring pattern.

CONSTITUTION: Self-recoverable spherical powder 23 carrying self-recoverable force is mounted on four positions which do not overlap wiring patterns 22 on a circuit board Pc. A die collet 26 drops and presses the wiring patterns 22 and electrodes of a chip part 24 via solder bumps 28. If the bumps 28 are solved by not blast or the like at a temperature a eutectic point or higher, the spherical powder 23 is deformed into an ellipse between the electrodes of the part 24 and the wiring patterns 22. If force applying pressure to lowering the die collet 26 is stopped to permit it to rise, the part 24 rises by several plus μm when the spherical powder is formed into a sphere with the seft- recoverable force so that envelop soldered parts 30 can be formed.