PRINTED WIRING BOARD, METHOD OF MEASURING PRINTED WIRING BOARD

PROBLEM TO BE SOLVED: To provide a printed wiring board of which deflection amount is small in heat cycle.SOLUTION: In a state of PKG in which many build-up layers are laminated on a first surface side of an insulating substrate 30, being vertically asymmetric about the insulating substrate 30, and a memory chip mounting substrate is mounted, a deflection state is maintained in which an end part side lowers to BGA side relative to a central part of the substrate at both normal temperature and high temperature, so that change amount of deflection becomes small, leading to less degradation of reliability in heat cycle. 【課題】 ヒートサイクルにおいて反り量が小さいプリント配線板を提供する。【解決手段】 絶縁基板３０の第１面側にビルドアップ層を多く積層し、絶縁基板３０の上下で非対称にして、メモリーチップ実装基板を実装したPKGの状態で、常温時、高温時、共に基板の中心部に対して端部側がBGA側に下がる反り状態を維持させることで、反り量の変化量が小さくなり、ヒートサイクルにおける信頼性の低下が少なくなる。【選択図】 図８