HI BOB,

AS ONE WHO HAS EDITED HUNDREDS OF DRILL FILES OVER THE YEARS FOR
BOARD FAB HOUSES, I WOULD REQUEST THE SAME THING THAT YOUR BOARD VENDOR
DID.  THE REASON BEING THAT A LOT OF TIMES NON-PLATED HOLES ARE DRILLED
INTO THE BOARDS AT THE SAME TIME THAT THE PLATED HOLES ARE DRILLED INTO
THE BOARDS.  THEREFORE, ONLY ONE DRILL FILE IS NEEDED.   YOUR HOUSE
WOULD PROBABLY PREFER NOT TO HAVE TO CHECK OTHER ANCILLARY FILES
EITHER WHEN THEY REALLY ONLY ARE GOING TO USE THE ONE THAT MOST MATCHES
THEIR DRILL MACHINE FORMAT.

AS A PROCESS NOTE, THE NON-PLATED HOLES THAT ARE DRILLED WITH THE PTH'S
WILL THEN BE TENTED IN IMAGING AND THEREFORE ENCAPSULATED TO KEEP THE
PLATING OUT.  FOR LARGER NPT HOLES AND IN CERTAIN OTHER SITUATIONS, A
SEPARATE SECONDARY DRILL FILE MAY BE NECESSARY TO BE DRILLED AFTER THE
PLATING PROCESS.  THIS DECISION IS MADE BY THE PCB ENGINEER AND IS BASED
ON THE TRADEOFF BETWEEN THE POSSIBLE DRILL MISREGISTRATION OF SECONDARY
DRILLING VERSUS THE POSSIBLE MFR DIFFICULTIES BY PRIMARY DRLLING NPT'S.

UNFORTUNATELY, THEIR IS NO WAY AROUND MANUALLY EDITING DRILL FILES.  FOR
INSTANCE, EACH PLATED TOOL GROUP IS ACTUALLY DRILLED ABOUT 4-5 MILS OVER
NOMINAL TO COMBAT THE PLATE DOWN IN THE BARRELS, SO THE HEADER NEEDS TO
BE ADJUSTED.  ALSO, THE DRILL COORDINATES ARE USUALLY RUN THROUGH AN
OPTIMIZATION PROGRAM TO REDUCE THE DRILL PATH ON THE MACHINES, A DUMMY
HOLE IN EACH TOOL IS ADDED TO CHECK FOR BROKEN BITS, STANDARD TOOLING
HOLES NEED TO BE ADDED, ETC........

AS LONG AS YOUR DRILL FILE IS IN EXCELLON FORMAT AND YOU SPECIFY WHICH
TOOL GROUPS ARE PLATED OR NOT ON THE DWG., YOU HAVE DONE ENOUGH.  IN
FACT, IN MY OPINION, IT IS MORE PREFERABLE TO LIST PLATING STATUS ON THE
DWG THAN PUTTING IT ELSEWHERE BECAUSE ENG WILL THEN USE THE SAME
DOCUMENT THAT QC LATER WILL USE TO CHECK THE BOARDS.

PLEASE FEEL FREE TO CONTACT ME IF YOU HAVE ANY FURTHER QUESTIONS.

JOHN DENTON
OMNI PWB
609-303-1220

Bob Walker wrote:
>
> HI Mike,
>
>  First, thanks for responding to my question because I have been trying
> to understand just what is in the files that I send to the board
> fabricators because my CAD tools now provide me with new options
> concerning them. It appears that my CAD vendor has done everything that
> you stated a board fabricator would probably want in a drill file, or
> files, and that is why I don't understand why he would still want just
> the one file. Just to repeat again, I can generate 3 types of drill files
> whereas each one contains an identical 'part program header' that lists
> all of the different tools needed for a design and they all use the same
> zero datum location. And if there is a plated and non-plated hole that
> reflects the same hole size from the design info, then the file will
> contain 2 tools, one for the plated and another for the non-plated holes,
> so that there doesn't have to be any manual editing of one tool sequence
> to separate the plated from the non-plated holes. So I could generate one
> file that contains coordinates for only plated holes, another file with
> coordinates for only non-plated holes or another file that contains both
> plated and non-plated holes, with separate tool selections for each one.
> The only problem that I can see with the combined file is that there is
> no way of distinguishing the plated tool selection from the non-plated
> tool selection. You would then have to refer to a fabrication drawing and
> the drill table symbols to figure that out.
>  I guess that in trying to reduce any possible errors in fabricating a
> board today, I would think that having 2 drill files (plated and
> non-plated) with the content that I have described above, would be better
> than having 1 file and having to refer to a fabrication drawing to figure
> out which are the plated and non-plated holes if they were both set to be
> the same finished hole size. Thanks again for your feedback.
>
> Bob Walker
> [log in to unmask]
>
>  ----------
> From:  TechNet
> Sent:  Friday, September 25, 1998 7:43 AM
> To:  [log in to unmask]
> Subject:        Re: [TN] drill files-plated/non-pl
>
>      The real problem is not having both plated and non plated holes of
> the
>      same diameter in the same file, but to have them in the same tool
>      sequence of the file.  The manual editing involved in separating
> them
>      has certainly seen its human factor.  Multiple files have also seen
>      their human factor.  Sometimes CAM systems won't give multiple files
>      the same zero datum and they could end up not registering correctly
> to
>      one another on the board.
>
>      Mike Mikucki
>      Product Engineering
>      Hadco
>
> ______________________________ Reply Separator
> _________________________________
> Subject: [TN] drill files-plated/non-plated holes
> Author:  Bob Walker <[log in to unmask]> at SMTPLink-Hadco
> Date:    9/24/98 4:45 PM
>
> Hi All,
>
>  I'm trying to better understand the process of drilling holes in a PCB
> and the files that are used by the board fabricators to do this. I am a
> PCB designer and presently send gerber files (fabrication gerber
> included) and a drill file (excellon format) to my board house for boards
> to be made. The fabrication drawing contains a drill table with symbols
> that represent each hole size and whether or not it is a plated or
> non-plated hole. I never allowed a plated and non-plated hole to be the
> same size in any of my designs because my CAD tools couldn't recognize
> that a plated and non-plated hole could be the same size and thus
> couldn't generate 2 different symbols for each. Well now my CAD vendor
> has provided me with the ability of tagging my padstacks as either a
> plated or non-plated hole so that I can generate a different drill symbol
> for my fab drawings. And I can also generate different drill files that
> can either include all hole styles, only plated holes or only non-plated
> holes which I thought would help my board fabricator out by not having to
> separate out the plated from the non-plated hole coordinates in the drill
> file. But when I called him to see if he could make better use of 2 drill
> files (plated and non-plated), he said he only wants the 1 file that
> contains both the plated and non-plated hole locations. Wouldn't it be
> better to have the 2 files? What don't I know? I would greatly appreciate
> all feedback from any designers or board fabricators.
>
> Regards,
>
> Bob Walker
> [log in to unmask]
>
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