| 摘要 |
PURPOSE:To more simply perform a partially parts exchange and apply no heat on other electronic parts by providing a metal layer of good heat conductivity on a wiring layer nearest to the surface layer of a multilayer printed wiring board. CONSTITUTION:Many surface mounting parts 2 are mounted on a multilayer print wiring plate 1 and its lead is wired on other pads by a wiring pattern from the pads 4 on a multilayer print wiring plate or connected to an inner wiring layer through a through hole 5 or connected with a rear surface layer. A copper foil layer 7 is provided in a range which is shown by dotted lines on the wiring layer nearest to a surface layer on which the pads 4 are provided and terminals 9 of the surface layer and the copper foil layer 7 are connected by a heat transfer hole 8. When a defect of a part of parts is found by an electric test after mounting, heat is applied on the copper foil layer 7 beneath the pads, a necessary pad group alone can be heated and parts exchange can easily be performed without heating of the other parts. |
