PRINTED WIRING BOARD, ITS BASE MATERIAL, AND ELECTRONIC CIRCUIT DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a printed wiring board which is capable of effectively preventing a lift-off such as the separation of a fillet or a land so as to improve a soldered joint in quality and reliability when a part is mounted by the use of lead-free solder, and to provide its base material and an electronic circuit device. SOLUTION: A printed wiring board 3 is equipped with a base material 4 on which a conductor layer 1 is provided, and an electronic part 5 is soldered to the conductor layer 1. The thermal expansion coefficient of the base material 4 of the printed wiring board 3 is 200×10<-6> / deg.C or below in the direction of its thickness, and the electronic part 5 is soldered on the conductor layer 1 of the printed wiring board 3 for the formation of an electronic circuit device.