i came late to this party, pls excuse anything i may have missed during
my scans of this thread which has digressed to bottom assy issues
WRT to bottom assy dwgs
what is wrong or missing with simply using the PPC w/ the mirrored
property to create PDFs or whatever files desired for bottom assy view dwgs?
works for me and assemblers
i have never done any of the things discussed here re bottom parts
WRT to pik files
just subtract BD_WIDTH - X in a formula in an excel file of the pik file
output and you are done in a few minutes for bottom side parts which are
clearly marked in the file
i don't really understand the need for all the machinations discussed
here about these issues
a larger issue for me is this:
what about all the parts in the pik file which are either thru hole or
'omits' or not machine placed for whatever reason
this is the most time consuming editing i see about that process
i suppose to be politically correct we should not use the terms 'top'
and 'bottom' but rather 'primary' and 'secondary' sides as recomended by
the IPC and common recent practice
ds
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Abd ul-Rahman Lomax wrote:
> At 11:42 AM 5/25/2006, Brad Velander wrote:
>
>>Abd ul-Rahman,
>> While I understand your comments, I offer the following.
>>Importing Gerber back to Protel is not the solution for this
>>documentation issue because of course the Gerber contains no
>>intelligent part information.
>
>
> The gerber solution is only for the purpose of producing flipped
> human-readable documentation; I've never needed to do this except for
> bottom-side assembly drawings. Yes, the gerber contains no
> intelligent part information, but this solution allows a single
> drawing to show both top and bottom assembly. If you want to make
> separate drawings, you might do something different, but.... you
> might still do what I suggested, only in a separate file.
>
>
>> Using Gerber would definitely not bring anything to the table when
>>creating P&P files because of the loss of the intelligence. Our P&P
>>files must have the bottom side flipped and re-oriented because our
>>manufacturing insists on have the documentation oriented as viewed
>>by the user and we manipulate these at the PCB file level prior to
>>generating P&P files and prints from a flipped and often rotated
>>version of the original PCB file.
>
>
> I'd think a better solution would be a transformation of the bottom
> side Pick and Place file, for the file part of it. This would then
> match the assembly drawing created as I suggested. I don't recall if
> Protel will mirror a P&P file, but it would be terribly easy to write
> a utility to do it. And I'd think any assembler would have software
> to do this....
>
> The original PCB file is all that machine intelligence needs; if the
> rotation and reference information are correct in the footprints, I'd
> think manipulation would not be necessary.
>
>
>> Similar issues arise when creating solder paste screens
>>because we must manipulate footprint apertures on certain specific
>>footprints, thus not having the footprint names would significantly
>>hinder our ability to identify the footprints needing manipulation
>>or doing it in an intelligent global editing type manner.
>
>
> All that data is in the intelligent part of the board. The
> bottom-side assembly drawing is just that, a drawing. Yes, you
> regenerate it whenever you make changes to a board. It would be nice
> to have a facility to do this; I think at least one service bureau
> created a utility for this purpose.... Again, solder paste screens
> are created from the Paste Mask layer, and the manipulation would be
> done in the intelligent part of the PCB board file. The "dumb" part,
> the bottom assembly drawing, is not used for generating pick and
> place files, nor should it be used for paste masks. It's just to
> present a bottom-side view to a human....
>
> Assembly drawings may or may not show SMT pads. If placement density
> is such that there is no room for pads and component legend
> ("silkscreen") then I may autoposition legend inside the part, and
> print it in the assembly drawing, but not in the silkscreen.
>
> Without going into all the details, the goal is to have a single
> board file that automatically will generate the needed fab files.
> I've always provided pick and place files that were not mirrored, and
> I never saw a fab house that wanted to be provided the flipped files.
> If they want to flip them, it ought to be practically one-button for
> them. Just like I don't flip bottom copper. It is less confusing if
> everything is generated as viewed from the top. Fabricators have been
> dealing with this for donkey's ages. (Yes, they mirror them in
> photoplot, or, perhaps more accurately, the *don't* mirror them,
> since with some processes they would mirror the *top* plot. Since I
> don't necessarily know which process they are going to use, I've
> always just given them the files one way; they know what to do with them.
>
>
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