
324 The Circuit Designer’s Companion
pressure for each package. With suitably ingenious mechanical design, it may also
contribute to the total thermal performance of the whole assembly.
9.5.4 Placement and layout
If you are only concerned with designing circuits that run at slow speeds with CMOS
logic and draw no more than a few milliamps, then thermal layout considerations will
not interest you. As soon as dissipation raises the temperature of your components more
than a few tens of degrees above ambient, it pays to look at your equipment and pcb
layout in terms of heat transfer. As was shown in section 9.4.3, this will ultimately
reflect in the reliability ...