On 23/10/2010 17:33, David wrote: > Hi, > > I have had some moderate success designing PCBs in Eagle and having them > made by BatchPCB. I currently use a fairly crude method of soldering > SMD parts, but it seems to work (info at http://tinyurl.com/2brjyn6). > I'm pretty happy with this workflow. > > However, the skills I built up manually routing double sided > through-hole boards with "huge" components don't translate well to > surface mount. > > As an example, see the board at http://tinyurl.com/35gdrpx (none of the > finishing e.g. silkscreen/ground pours is done yet). It is a simple > breakout for the FT232RL so I can use it with a breadboard, but getting > all the wires routed without hundreds of vias is challenging me. > > So I would welcome any tips for SMD boards. Do people use the > auto-router? Would it be more sensible to layout on 2 sides somehow > (e.g. Vcc/GND on one, signal on the other). Do I just need lots more > practise at component layout and routing? > > And yes, I know you can buy these things. But I'd rather spend a few > weeks reading a datasheet and learning about how things work. > > David My advice is not to use the autorouter (hardly anyone ever uses them),=20 they never work for anything but the simplest, low speed boards where=20 routing is not critical. Some people use them for selected (non=20 critical) bits on boards which is okay as long as you know what you are=20 doing I suppose. Personally I never use them. With 2 layer boards often an orthogonal method is used (vertical traces=20 one side, horizontal the other) with a ground plane/fill on one side -=20 if you can route as much on one side as possible and leave the other for=20 a nice (mostly) unbroken ground plane that's good for simple boards. At=20 the very least route power and ground together to minimise loop inductance. For high speed or mixed signal stuff it's better to use a 4 layer (or=20 above) board and have layers dedicated to ground/power planes, this=20 makes signal integrity/EMI issues much easier to deal with. Vias are a=20 necessary evil with SMD, so get used to having loads of them on your=20 board, if you need a really solid connection you can "stich" a few together= .. I would grab a couple of books as it's a complex subject with many=20 differing views on the best way to do things (such as whether to split=20 ground planes between analog and digital or not), there are plenty=20 around - check out some of the documents on this page, they should get=20 you started: http://search.analog.com/search/default.aspx?query=3Dpractical+analog+desig= n+techniques&local=3Den=20 Also a couple of books are: High Speed Digital Design (Johnson & Graham)=20 and Real Analog Solutions for Digital Designers. I'm sure there are more=20 PCB specific books around though if you check Amazon.. As you say, practice will help - after making a few boards you should=20 start to get used to what's important. --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .