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32 The PCB Magazine • May 2015 series of plating experiments performed in ver- tical continuous pilot plant plating equipment at Applied Equipment Limited (AEL) and NanYa (Taiwan). The effects of both these parameters on fill- ing performance were significant, with the re- sults showing that the impact of solution flow rate is the strongest. While lower levels of so- lution flow rates were found to improve hole filling performance; depending on application, this improvement sometimes came at the price of seam void formation. A flow ramp scheme, accompanied by good wetting during pre-clean- ing, reduced void formation while maintaining good hole filling performance. It is imperative that agitation parameters be carefully chosen to match plating cell design and application. It is also important to note the positive value of cur- rent density ramp accompanied by flow ramp on reducing void formation. A similar test was then conducted in which current density (CD) was varied. The intention of this test was to demon- strate the broad capability of the process that has been developed. Table 3 shows the effect of current density on through-hole filling perfor- mance. Consistent filling was achieved across a wide range of current density. ELECTrOPLATING THrOUGH-HOLES wITH DIFFErENT GEOMETry continues FEaturE Table 2: Plating performance as a function of flow conditions.