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126 PCB007 MAGAZINE I APRIL 2020 sembly panel? Or is it cost-effective to manu- facture only if incorporated into a multi-image production panel—whether of the same design or a mixture of designs? From the point of view of the PCB fabricator, it is clearly bad practice to interfere with a cus- tomer's design by adding balancing copper as non-functional areas within the layout, unless this is done in consultation with the design- er and formally approved before the design is signed-off. But on a panel, balancing copper—alterna- tively termed "copper thieving"—may be legiti- mately added to the panel border and in the spaces in between individual boards in order to improve the uniformity of electroplated copper thickness distribution by effectively stealing some of the plating current that would other- wise tend to be concentrated on sparse features. From a production standpoint, if the individ- ual boards in a multi-image panel have an un- even copper distribution, or if two or more de- signs are incorporated in the panel, there could be some benefit in arranging their relative po- sitions and orientations to improve the unifor- mity of electroplating. Maybe counterintuitively, the yield might be improved by put- ting fewer images on the pan- el with more space between them to allow for thieving. Who carries the responsi- bility? As long as the designer has reasonable sympathy for the process engineer respon- sible for the pattern-plating line, it generally depends on the experience of the pre-pro- duction engineer sat at their CAM station to make a best- guess compromise with the objectives of satisfying the acceptance specification and minimising the anxieties of the quality engineer. What if the pre-production engineer could rely on the help of a software tool to eliminate the guesswork and offer a consis- tent and repeatable solution? One less thing to worry about. I had the opportunity to sit in on a webi- nar presented by Robrecht Belis, manager of the surface finishing business unit at Elsyca—a Belgian company specialising in the simulation of electrochemical processes. He demonstrated plating simulation software designed to assist the PCB pre-production engineer in identify- ing plating problem areas, optimising panel layout, and applying auto-intelligent copper balancing as part of the CAM process to pro- vide a right-first-time solution for production. Although the primary objective of panelisation was to have as many PCBs as possible on the panel, there was no benefit unless every PCB was within specification for copper thickness (Figure 2). Belis commented that a straightforward Win- dows laptop computer had adequate perfor- mance to run the simulation software (signifi- cant in the circumstances, as he was required to be working remotely from his office because of social-distancing regulations). In his live demonstration, he began by inputting Gerber- Figure 2: Elsyca's software is designed to assist the PCB pre-production engineer in identifying plating problem areas.

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