The projects im currently working on, if im to make them fit into the equipment they are designed for (ie, not just remain 'bench experiments') require converting to compact PCBs using SMT parts.
Designing PCBs properly requires following a few special rules. Sadly, the auto-routers provided with most PCB CAD packages fail to follow these rules properly. One of these rules is that the use of blind vias (that is through board connections without a through hole component legs) should be kept to an absolute minimum.
This leads to a big problem with the sort of ultra compact, digital electronics im working with. Up until now, the top copper of a PCB has, in most of my work, been strictly RF groundplane. Now, I find im having to work with both top and bottom copper as signal lines, as well as power and ground connections. Add into this the additional rule that top copper tracks cannot pass across IC pin pads except where the package is large enough, such as a SOIC, then any auto-router naturally creates multiple blind vias.
So I find myself manually routing PCB layouts, not on the CAD packages, but on paper, with the help of several coloured pens. By playing with the orientation of the IC packages, eventually it is possible to come up with an effective layout that obeys the rules.
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