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August 2015 • The PCB Magazine 69 have even the smallest chemical unbalance or the tank design is wrong, you will know quickly. Along with chemical balance, an equally important area is correct tank design. A tank with limited panel motion, not enough airflow or wrong impingement design will never give you top-notch plating quality. The design of the copper tank should have the correct distance between the anodes and the panel; the panels should have at least 2.5" of travel on the cross slides. I prefer moving the panel along the same plane as the anodes which controls plating even - ness as you move the panel across the differ- ent plating speed of the anode surface area, but movement towards the anodes works almost as good. I have used vibrators and they do work well in very small-hole situations, but they can also create problems of micro-bubbles on the surface created by the vibration. I don't use vibrator units all the time, only when I need to. I find a kicker works better than vibration (i.e., a solenoid that kicks the rack every minute or so to remove any hydrogen bubbles lodged in the holes, as opposed to a full on ultra - sonic type vibrator). One note of caution: Do not use vibrators with carbon electroless solutions, such as Blackhole or Shadow; the shaking of the vibrator will loosen and remove carbon particles from the holes. This will then pollute your cop- per tank, producing an outcrop of copper bumps on the surface so bad your boards can be sold as sandpaper. The panel racking should be stout and able to carry your largest currents; I do not like small top racks that only grip in one or two clamps because this produces too high a current area at the singular clamping area. I like racks which have four or five protected clamps down each side to help distribute the high current. Remem - ber to make sure you have a small current avail- able when you place your panels into the copper plating solution, this starts the action of plating Figure 1: a 15 oz., 6-layer PcB. FeAture PLATING AND QUALITY ARE CLoSE PARTNERS continues