The problem of conductive material remaining in the non pth holes on direct 
plate systems does not exist for carbon because all conductivity is eliminated 
in the dry film stripper after plating. As long as the holes can be tented both 
sides they can be drilled with the pth holes. Palladium systems would be the 
same as electroless copper and the palladium layer would be removed in the 
etching process.

Paul Gould
[log in to unmask]

> Just a word of warning, there have been several TechNet  e mails about this 
> first drill approach being dangerous if an alternative to electroless copper 
> system is in use and any circuitry does not have a clearance around the 
> nonplated hole as the alternatives do leave the hole with a unremoved 
> conductive layer that can result in leakage.  Reportedly it is not like the 
> electroless where you can remove all the plating.
>  ----------
> From: [log in to unmask]
> To: [log in to unmask]
> Subject: Re: MISC: drill files 1 or 2
> Date: Wednesday, September 25, 1996 1:59PM
> 
>      Since the effort is made to drill as many of the holes in the
>      primary drill operation as possible, we prefer that the drill
>      be sent as one file to reduce the number of steps in the
>      CAM operation. Non-plated holes are only drilled in a
>      secondary operation if they cannot be tented in the imaging
>      plating operation.
>         Don Bloye
>      PC World
> 
> 
> ______________________________ Reply Separator
> _________________________________
> Subject: MISC: drill files 1 or 2
> Author:  [log in to unmask] at INET
> Date:    9/25/96 2:04 PM
> 
> 
> Hi - :)
>    What is prefered from the fabricators point of view:
>    One drill files containing both plated and non-plated holes?
>                            or
> Two drill files one plated the other non-plated?
>    Reasons?
>        ---------------------------
> John Laur
> Rockwell Automation
> Allen-Bradley Co Inc.               1201 South Second Street
> Milwaukee, WI 53204
> +1 414 382 2162 (fax)
> +1 414 382 2393 (phone)
>    [log in to unmask]
>  ---------------------------
 

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