> I've read all the threads about wanting to view a board from the
> bottom up and I cant figure out why anyone would do this.

Because it can eliminate having to manually transpose dimensions 
and therefore, a source of error.

> The IPC
> -D-325 Documentation standard  states in        sec 4.2.6 VIEWING :  
> The layout of the board design should always viewed from the primary
> side of the board. blah blah blah..

Sure. That makes perfect sense once it is complete. Does it define 
"primary side" ? Is that the side with the most bits, the one the 
through-hole parts are on, the one that matches all the mechanical 
drawings of the complete product or something else ?

I've never seen a drawing of a chair with the legs at the top, but I 
am sure it spends some time like that at the upholsterer. Why 
should it be any different when I am laying out a PCB ?

In fact, I have a job at the moment where it would be a really useful 
tool. There are two boards that plug together component side to 
component side. If such a tool existed, I could place components 
on both sides of a single outline so that I could check for 
interferences as I go. I could also put the connectors on top of 
each other so that I know they will match up. Once I am happy, I 
could select everything on the bottom layer and flip them with a 
copy of the outline. Now I have two boards as they will be 
manufactured on a panel, with the components on the top, no 
transposition errors and I still have the ability to keep in sync with 
the schematic.

Steve.


======================================================
Steve Baldwin                Electronic Product Design
TLA Microsystems Ltd         Microcontroller Specialists
PO Box 15-680, New Lynn      http://www.tla.co.nz
Auckland, New Zealand        ph  +64 9 820-2221
email: [EMAIL PROTECTED]      fax +64 9 820-1929
======================================================

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