Re: [sdiy] Surface mount

[Roman]

	SMD parts are just smaller. That's the only difference, but just because of that, other issueas become important: 

	- power dissipation of discrete components is much smaller than thru-hole, e.g. resistors lower than 1k should be rather in large 1206 package if expecting about 10V span (my rule of thumb, not necesarily true), transistors will self-heat easily causing drift problems, etc. 

	- caps larger than few nF are either low voltage (16V and less) or made from nonlinear crap that has huge tempereature dependence, dispersion etc. Unless you use 1206 and larger parts. 

	- ICs also have less power dissipation ability and that may cause drift problems 

	- distances between pads are smaller, so tracks also must be smaller and dense. That increases capacitance, crostalk etc. 

	- the layout is different just because there are no holes for components. Design philosophy is completely different. 

	- because of smaller size the whole circuit will heat up to higher temperature than identical board using thu-hole design 

	But there are also benefits: 

	- smaller inductance of traces and inner-leads of the IC, meaning power decoupling can be done right for a change 

	- thermal contact between 2 glued parts is better, say for expo converter. Less plastic to heat. 

	- all the neat stuff comes in SMD now, like fine opamps, precision resistors, etc. 

	- IMHO soldering SMD is faster and easier than thru hole. 

	- and the best of all - it looks so good ;) 
	So answering your question, I say no, it won't work exactly the same, but there's no human who could tell the difference. Some precision equipment might show it, but probably not in audio stuff, which is basically DC. :) 
	Roman 
---- Wiadomość Oryginalna ----
Od: Laurie Biddulph 
Do: Synth DIY 
Data: Fri, 2 Jan 2004 08:24:46 +1100
Temat: [sdiy] Surface mount

   Hi, Hope everyone had a good Xmas holiday and New Year.   I would like to get some feedback on how you feel about using surface-mount components in analogue synths as opposed to the good old thru-hole component. Would two identical circuits built using the two different technologies sound the same? 
Best Regards
Laurie Biddulph
http://www.elby-designs.com (http://www.elby-designs.com/)

 
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