| 摘要 |
As BGA's and CSP's become widespread, the number of steps in soldering module boards to rigid printed wiring boards increases. A printed circuit board warps due to heating during reflow, so even if mounting is carried out at a temperature sufficiently exceeding the melting point of a solder alloy, there was a problem of the phenomenon of fusion defects in which the solder bumps of a module board of a CSP, a BGA, or the like and the mounting paste do not fuse or parts having leads and solder paste do not fuse, resulting in conduction defects. Means for Solving the Problem When soldering a module board to a rigid printed wiring board, a post-flux is applied to a module board before mounting, a solder paste is then applied to the rigid printed wiring board, and the module board is soldered.
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