> they were meatball 10/10 mostly 12/12 bds
> there was a giant pour on the entire top
> the clearance on the pour was 20 mils all the way around the pads (to
> make it easy and not get shorts!)
> 
> they said with a big plane it is harder to etch
> 
> there must be at least a bit of truth to that because i have had this 
> trouble with this type of board from 3 different shops - albeit not the
> highest tech shops kicking around

I did this type of pour and had the board house slap my wrists and tell me 
because of it they would have to electrically test the boards even though 
they were very simple. 

The explainattion was that if you have a big pour with lots of copper on 
one side you need about the same copper on the other side to balance it. 
Otherwise the acid on one side gets weak while the other side remains 
strong, resulting in overetching on one side or underetching on the other. 
Better circulation in the acid bath helps, but yield still goes down and 
thus cost goes up.

If you do a big pour on only one side you should do it with a crosshatch 
pattern so that the copper is balanced and etching is even.

After that wrist slapping I've have learned my lesson and I try hard to 
keep the copper even.


Robert D. LaMoreaux
MTS Systems Corp. 
Powertrain Technology Division
4622 Runway Blvd.
Ann Arbor, MI 48108
734-822-9696
Fax 734-973-1103
Main Desk 734-973-1111

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