In the circuit substrate which includes multiple wiring which were pulled out from each of implemental structure of the circuit substrate and

摘要

PROBLEM TO BE SOLVED: To provide a circuit board in which mounting positional shift of a semiconductor element with bumps due to incomplete application of a solder material is suppressed, when the semiconductor element with bumps, e. g. a BGA, is mounted on a FPC board, or the like, by solder reflow, and to provide a mounting method of the semiconductor element with bumps.;SOLUTION: The circuit board includes a plurality of pads for mounting the semiconductor element with bumps and a plurality of wiring lines led out from the plurality of pads, the mounting structure of the semiconductor element with bumps, the electro-optical device, and the electronic apparatus. The circuit board has a region 435 where the longitudinal pitch of the plurality of pads 413a is different from the lateral pitch thereof, and the plurality of wiring lines are led out from the longitudinal or lateral side of wider pitch of the plurality of pads. The region where the longitudinal pitch of the plurality of pads is different from the lateral pitch thereof is prepared in a position opposed to near the center, or near the periphery of the bottom face 433 of the semiconductor element.;COPYRIGHT: (C)2006,JPO&NCIPI