| 摘要 |
A method of providing selective silver plating to a lead frame structure 10 performs the silver plating operation prior to etching the lead frame, thereby avoiding mechanical damage to the lead frame during plating, and producing finished silver spots 24 on the top surface of the lead frame only, with no plating on the gauge. The disclosed method includes the steps of applying a layer of photoresist 42 to a surface of a sheet of lead frame material 40, exposing areas of the photoresist such as to define selected regions 44, developing the photoresist 42 to uncover the lead frame material 40 at the selected regions 44, and plating the surface of the sheet defined by the layer of photoresist 42 with an electrically conductive material 46. The method further includes subsequent steps of stripping the layer of photoresist 42 from the surface, applying a layer of a second photoresist 50 to the plated surface, exposing areas of the second layer of photoresist 50 such as to define an unexposed lead frame pattern, the selected regions 44 corresponding to electrical contact locations on the lead frame pattern, and developing the photoresist 50 to uncover exposed regions 52 of the sheet of lead frame material 40. The method includes a final step of etching the sheet 40 to remove material from regions 52 uncovered by the second photoresist layer 50.
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