概要（Overview）

Meco's Solution for Accurate Silverspot Plating Where Mechanical Masking Becomes Impossible! In general, spot tolerances of ± 125 micron in x and y direction can be reached by mechanical masking systems like Meco's patented spot tool technique. The disadvantage of mechanical masking is that you often get bleed-out of silver on the cutted edges of the leads as shown. Undesirable metal coating on these functional areas may result in poor adhesion of the mould compounds, while any silver extending beyond the package after molding may cause short circuiting among the leads as result of silver migration. Looking at the trends in leadframe design, ongoing attempts towards further miniaturization are observed. These developments result in a high lead density, thinner leadframes and packages. Such complicated and fragile leadframes are not stamped in reel to reel form, but more frequently in etched cut strips. It also requires a higher accuracy of silver spot position (±50 micron) like for QFN leadframes.