Comments in text:

> -----Original Message-----
> From: Robison Michael R CNIN [mailto:[EMAIL PROTECTED]]
> Sent: Thursday, 21 February 2002 9:37 AM
> To: 'Protel EDA Forum'
> Subject: [PEDA] how does smt work ??
> 
> 
> hello,
> 
> well, thats a pretty dumb question, isn't it?  hahaha.
> but i'm serious.  i'm trying to reproduce a board which
> has smt top and bottom, and it appears that some of the
> smt pads overlap from top to bottom.  

There are no dumb questions - just dumb people. :-)

> 
> so how do smt pads work?  on a thru-hole, they obviously
> go thru the entire board.  how far does a pad go thru as
> an smt?  obviously it has to at least burrow thru to any
> layer it runs on, but do top and bottom overlapping smt 
> pads necessarily net together?  i'm confused.

An SMT pad exists on one signal layer only. To connect between signal layers
(top and bottom for example) vias are needed.

> 
> let me state that i realize many complex things are 
> possible (blind and buried vias come to my mind), but
> somehow i don't think this is the case with this board.
> but i'm not sure.
> 

The reason you may not notice the vias is that they may be tented (covered
with solder mask) or under the component (bad design practice).

> thanks, miker
> 

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