[sdiy] components, smd and pcb

[Sowa Roman]

yes, you can put traces between SMD IC, look:
http://membres.lycos.fr/romcio/krospcb.gif (16-lead SOICs)

It's true that SMD layout requires much more vias than thru-hole,
but anyway it take's less space, even if not designed too carefully.

I'd also add other advantages:
- decoupling capacitor can be closer to silicon
- discrete transistors can be better thermo-coupled (less plastic)
- you can solder passive components stacked one on top of the others
and it still looks good (e.g. making non-standard values by paralell
connections)
- cut wires from thru-hole components have bad habit of flying all over the
place
- you don't have to see other side of board. It can be glued to the wall and
still
you can do all service (assuming traces aren't broken)

My worst disadvantages are:
- I can't find decent, cheap SMD connectors. I mean any kind!
- same sa above for 50ppmTK 0603 resistors 
- and forget about polystyrene SMD caps :)

Roman

""-----Original Message-----
""From: jorgen.bergfors at idg.se [mailto:jorgen.bergfors at idg.se]
""Sent: Monday, March 25, 2002 3:03 PM
""To: jhaible; synth-diy at dropmix.xs4all.nl
""Subject: Re: [sdiy] components, smd and pcb
""
""
""
"">Cons:
"">* As the SMD parts are on "the other side" now, I have
""   >tothink in mirror image when I route the traces.
""
""   I'd like to add the following:
""
""   * You can't put traces between the pins of the ICs
""
""   * You can't fit as many traces under the IC packages. 
""Under a normal DIL
""   package, I usually fit up to four traces.
""
""   /Jorgen - cramming the entire sound generation circuits of 
""the TR-808 on
""   one 160x233 mm single sided board.
""
""
""
""
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