| 摘要 |
A solder-precoated wiring board on which devices and component can be mounted at fine pitches and which can be manufactured with a high productivity. A solder layer on a conductor for connection of electronic components on the wiring board comprises an Sn thin film layer formed by, for example, Cu-Sn substitution reaction on the basis of forming a Cu-complex of thiourea, and a Pb-coated Sn layer made by forming an Sn film, forming Sn crystalline particles film by Sn disproportionating reaction based on selective deposition on the Sn film, and substituting Pb for at least part of the Sn crystalline particles by Sn-Pb substituting reaction on the basis of the ionization tendency. It is desirable to melt this solder layer, and then, cool it to form an alloyed layer. <IMAGE> |
