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APRIL 2020 I PCB007 MAGAZINE 127 format files for Side 1 and Side 2 of the panel layout and defining the target plating thickness and upper and lower limits. The system gave a colour-coded indication of the expected thick- ness distribution, showing where it was and was not within specification limits. It was pos- sible to display both sides on the same screen, and many other analytical and statistical func- tions could be selected. The software could be configured to relate to a fabricator's particular electrolyte and plating cell geometry. Bellis commented that the only control fac- tors accessible to the CAM engineer were cur- rent and time. The process engineer at the plating line can control more parameters, like tooling, the amount and position of panels on flight bars, etc. But beyond those parameters, the uniformity of plating depended on how the panel was laid out in the CAM operation and could be predicted by simulation software. On the screen, the copper plating thickness at any point could be seen by simply pointing the mouse cursor at it. Was there a requirement to improve the cop- per thickness distribution? How could this be done? Maybe the distribution could be en- hanced by modifying the panel layout? Any changes could be quickly validated by the sim- ulation software, and the panelisation process repeated until an acceptable layout had been achieved. Alternatively, the automated copper balanc- ing facility could be used, with the CAM engi- neer defining the limits of the required thick- ness distribution and specifying the no-go zones and minimum clearances from the ac- tive PCBs. The software was also capable of "improving" the design of active PCBs, but this was a matter for discussion with the design au- thority, as mentioned previously (Figure 3). Using the simulation software, Belis dem- onstrated the improvement that had been achieved by the addition of balancing copper, emphasising that the system had been very se- lective in adding it only where it was needed. The data was still in an editable form should any further information require to be included and could subsequently be output as part of the normal manufacturing package. An impressive demonstration! In my days as a technical manager in a PCB fabrication shop, I would have been delighted to have had ac- cess to such a facility. Having been raised in the wet-processing area, I would be inclined to disagree with Belis's claim that his simula- tion software can "make every CAM engineer a plating expert" since he makes no mention of buckets or Wellington boots. PCB007 Figure 3: An example of a copper balanced panel following simulation and optimisation.

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