| 摘要 |
PURPOSE:To make it possible to solder more reliably than ever a solder layer to a conductor layer by a method wherein a flux layer is formed on a metal thin film layer, which is formed on the whole surfaces of an insulating layer and the conductor layer and has a good solder wettability and a property of being well bitten by solder, and they are dipped into a fused solder tank to form the solder layer. CONSTITUTION:A metal thin film layer 5 made of a material containing a metal having a good solder wettability and a good solder corrosion property, such as tin, silver, copper and the like, is formed on the whole surfaces of an insulating layer 3 and a conductor layer 4, which are formed on a circuit board, by electroless plating. After that, a flux layer is formed, the board is dipped into a fused solder tank to give a solder to the upper part of the layer 4 and a solder layer 6 is formed. Thus, with the progress of solder-wettability on the layer 5, an action of being wet with solder progresses on the layer 4 lower the layer 3 as well and the layer 6 can be reliably soldered to the layer 4. |
