Noise and Grounding 385be physically large, determining the PCB size, and in typical circuitry there are a large
number of discrete resistors, etc., that can be used for jumping tracks.
Bear in mind that single-sided boards need thicker tracks to ensure adhesion in case
desoldering is necessary. Adding one or more ears to pads with only one track leading to them
gives much better adhesion and is highly recommended for pads that may need resoldering
during maintenance; unfortunately, it is a very tedious task with most CAD systems.
The advantages of double-sided PTH for power amplifi ers are as follow:
● No links are required.● Double-sided PCBs may allow one side to be used primarily as a ground plane,
minimizing cross talk and EMC problems.
● Much better pad adhesion on resoldering as the pads are retained by the through-
hole plating.
● There is more total room for tracks so they can be wider, giving less volt drop and
PCB heating.
● The extra cost is small.13.1.5 Power Supply Printed Circuit Board Layout
Power supply subsystems have special requirements due to the very high capacitor-
charging currents involved.
● Tracks carrying the full supply-rail current must have generous widths. The board
material used should have not less than 2-oz copper. Four-ounce copper can be
obtained but it is expensive and has long lead times; it is not really recommended.
● Reservoir capacitors must have the incoming tracks going directly to the
capacitor terminals; likewise the outgoing tracks to the regulator must leave from
these terminals. In other words, do not run a tee off to the cap. Failure to observe
this puts sharp pulses on the DC and tends to worsen the hum level.
● The tracks to and from the rectifi ers carry charging pulses that have a
considerably higher peak value than the DC output current. Conductor heating
is therefore much greater due to the higher value of I^2 R. Heating is likely to be