US Patent 7714233 Printed wiring board

A printed wiring board including a wiring substrate provided with at least one conductor circuit, a solder resist layer formed on the surface of the wiring substrate, covering the at least one conductor circuit, conductor pads formed on a part of the at least one conductor circuit exposed from respective openings provided in the solder resist layer for mounting electronic parts, and solder bumps formed on the respective conductor pads. The ratio (H/D) of a height H of the solder bumps from solder resist layer surface to an opening diameter of the openings are made to be about 0.55 to about 1.0 with the pitch of the openings provided in the solder resist layer of about 200 μm or less.