| 摘要 |
PROBLEM TO BE SOLVED: To solve such a problem that although a solder layer is generally provided on a copper layer exposed to the substrate surface by means of a solder leveler, in order to prevent oxidization of the copper layer, the solder does not fit to the inside of a small diameter through hole due to surface tension, in a substrate including a small diameter through hole having a diameter of 0.2 mm or less, because the viscosity of the solder is high, and thereby the copper layer is exposed, as it is, to the inner surface of the small diameter through hole.SOLUTION: A printed wiring board includes a board 1b, component attachment parts 4, 5 provided on at least one side of the board 1b and to which a component is soldered and a copper layer 6 of a small diameter through hole conductor 58 provided on the inner surface of a small diameter through hole penetrating the board 1b, a gold plating layer 51 provided on the copper layer 6 and a solder layer 7 provided on a gold plating layer 51 at the component attachment parts 4, 5. |
