PURPOSE: To prevent Manhattan phenomenon generated during mounting of a surface mount part by providing a buffer pattern between a land and a wiring pattern to make heat capacity of right and left lands equal.

CONSTITUTION: A wiring pattern 31 is connected to a left electrode land 21 of a part 1. A wiring pattern 32 is connected to a right electrode part land 22 of the part. In the state, heat capacity of the left electrode part is smaller than heat capacity of the right electrode part and Manhattan phenomenon is generated. Since Manhattan phenomenon is generated by a time lag in melting of solder in right and left electrode parts of the part 1 during mounting, buffer patterns 11, 12 are provided between a land and a wiring pattern to make heat capacity in the right and left electrodes equal. Thereby, it is possible to eliminate the time lag in melting of solder and to prevent generation of Manhattan phenomenon.