PURPOSE: To prevent a solder plated layer from running into a gold plated layer during the fusing step by a method wherein, after finishing the partial gold plating step, the whole surface of a substrate is underneath copper plated. ;CONSTITUTION: After the formation of a gold plated layer 16, a thin underneath copper plated layer 30 is formed on the whole surface of a substrate 10. Next, the part excluding the circuit pattern to be the plated layer on the surface of this underneath layer 30 is coated with a resist as a masking tape so as to form a solder plated layer 34. Next, when the resist 32 is released to perform the etching step, the solder plated layer 34 fills the role of the mask making the appearance as shown in the figure. At this time, the underneath copper plated layer 30 is etched away further inside the edge of the solder plated layer 34. That is, the solder plated layer 34 is to overhang the underneath copper plated layer 30. In such a constitution, this overhung part C melted down by fusing step will not spread over the surface of the gold plated layer 16 due to the high surface tention of the solder itself to be stopped at the edge of the underneath copper 30.;COPYRIGHT: (C)1993,JPO&Japio
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