CATHODE ROCKER OSCILLATION
To obtain the requisite relative motion between work and solution, it is generally easier
mad more efficient to move the work than the solution. Thus, cathode rocker agitation is very
widely used in printed circuit board (PCB) manufacture, nickel and precious metal plating,
and wherever air agitation is undesirable.
The work movement can be vertical, horizontal, or a combination of the two. In many
cases, the direction of motion is inconsequential; in other cases, for example in PCBs with
plated-through holes, motion in one particular plane can be far more effective in propelling
fresh solution to the point of interest than movement in the perpendicular planes.
For small tanks, the simple single-rod system shown in Fig. 5 is an off-the-shelf
accessory that provides horizontal agitation. If vertical agitation is desired, it can often best
be implemented with a see-saw arrangement that will minimize energy consumption and wear
and tear, such as is shown in Fig. 6.
Whichever plane of oscillation is chosen, care should be taken in selecting and mounting
the components to ensure that grease from the rocker will not leak into the tank, and
conversely that racks lifted out of the tank will not drip corrosive chemicals onto the rocker
system. In trying to provide for long service life, simple rollers of Teflon or polyethylene
riding on stainless steel axles can be expected to endure the plating room environment more
successfully than even the finest metal bearings.
The speed and stroke will vary depending on the application, but 15 to 40 cycles per
minute with a stroke length of 2 to 6 in. covers the great majority of cases. Smooth motion
suffices to prevent localized ion depletion with minimal risk of contact breaks, but a
trip-hammer effect is especially well suited for dislodging troublesome gas bubbles in
electroless plating operations.
For large installations and where the work is to be oscillated in several tanks, it is
possible to fabricate a ladder-shaped framework, such as is shown in Fig. 7, to sit atop the
tanks and move all the workloads in tandem. This approach is widely implemented in
production plating of printed circuits. The ladder must have sufficient integrity that the
oscillatory energy is not lost to structural flexure. Again, plastic bearings and corrosion
resistant construction should be used.
CATHODE ROCKER OSCILLATION
To obtain the requisite relative motion between work and solution, it is generally easier
mad more efficient to move the work than the solution. Thus, cathode rocker agitation is very
widely used in printed circuit board (PCB) manufacture, nickel and precious metal plating,
and wherever air agitation is undesirable.
The work movement can be vertical, horizontal, or a combination of the two. In many
cases, the direction of motion is inconsequential; in other cases, for example in PCBs with
plated-through holes, motion in one particular plane can be far more effective in propelling
fresh solution to the point of interest than movement in the perpendicular planes.
For small tanks, the simple single-rod system shown in Fig. 5 is an off-the-shelf
accessory that provides horizontal agitation. If vertical agitation is desired, it can often best
be implemented with a see-saw arrangement that will minimize energy consumption and wear
and tear, such as is shown in Fig. 6.
Whichever plane of oscillation is chosen, care should be taken in selecting and mounting
the components to ensure that grease from the rocker will not leak into the tank, and
conversely that racks lifted out of the tank will not drip corrosive chemicals onto the rocker
system. In trying to provide for long service life, simple rollers of Teflon or polyethylene
riding on stainless steel axles can be expected to endure the plating room environment more
successfully than even the finest metal bearings.
The speed and stroke will vary depending on the application, but 15 to 40 cycles per
minute with a stroke length of 2 to 6 in. covers the great majority of cases. Smooth motion
suffices to prevent localized ion depletion with minimal risk of contact breaks, but a
trip-hammer effect is especially well suited for dislodging troublesome gas bubbles in
electroless plating operations.
For large installations and where the work is to be oscillated in several tanks, it is
possible to fabricate a ladder-shaped framework, such as is shown in Fig. 7, to sit atop the
tanks and move all the workloads in tandem. This approach is widely implemented in
production plating of printed circuits. The ladder must have sufficient integrity that the
oscillatory energy is not lost to structural flexure. Again, plastic bearings and corrosion
resistant construction should be used.
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