Data Sheet

PCB Layout
155
Suppress Islands
An island is defined in the PCB Layout as a block of copper or zone area in which no valid
connections can be made. When checked, the layout will remove all such blocks from the
board, leaving only areas of copper with connections.
Allow Nesting
It is quite common, particularly with larger boards, that the flow of a zone will encounter an
obstacle through which it cannot pass. When checked, the zone will jump over the obstacle and
continue flowing across the board.
This is a very useful option for example on busy boards or where you want to connect a pad
where the topology of the board makes it impossible for a single zone flow to get through.
Given our relatively simple board, the default options are ideal for our purposes. Selecting the
nesting option will have no effect for example as there are no inner boundaries on the board.
However, if you want to experiment you should find that if you uncheck ‘suppress islands’
option, the resulting zone populates far more of the board that in our initial configuration.
We have covered only the basics of power plane functionality here relevant to our current
design. For more information, including split planes, zone keepouts, and bridge tracking please
see the power planes section of the reference manual.
Slots
To complete the layout of the board we need to return to our temperature/humidity sensor (U3).
In order to make accurate measurements, we want a thermal cutout around this part, ensuring
that the temperature we are measuring is actually the environmental temperature and not
conducted heat from the PCB.
You may remember that we placed a keepout area around this part to prevent the autorouter
from placing tracks through the area we want to cut out. Start by zooming in around U3 and