Effective etchback is desmear, but if it is greater than 25 micron it's nonconforming.  Effective desmear is not conforming etchback, UNLESS you're aggressive enough to meet the requirements of the controlled removal :)
This is why I said that to have a meaningful debate now-a-days you have to separate the measurements from the pre conceived notion of the processes used to obtain that condition.

Chris    

-----Original Message-----
From: IPC-600-6012 [mailto:[log in to unmask]]On Behalf Of Werner
Engelmaier
Sent: Monday, April 02, 2007 9:10 AM
To: [log in to unmask]
Subject: Re: [IPC-600-6012] Etchback vs. Desmear


Hi Tom,
> I spent a good deal of time Friday trying to find out. So far, they're
> telling me that the study was funded by the government and can't be
> released. 
> Freedom-of-Information Act?

> I'll keep digging since I thought the industry in general had
> come to the same conclusion that in today's world of better processes and
> materials, along with process control, etchback is a liability more than an
> asset. Many high reliability customers have reduced the maximum etchback
> allowed on their product for that reason, 
> Agreed

> but have not yet allowed desmear
> because they don't want to invest time to qualify  a supplier's desmear
> process.
> I do not understand what that mens, how can you not have/allow desmear? 
> Isn't it the same process only by a different name?
> 
> 
Werner



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