At 09:52 PM 2/28/2002 -0500, Mike Reagan wrote: >Y' all havent heard my response yet because e Im trying to visualize if >using one paste screen for alternating top and bottom panels will work. ( >it was the best expanation I heard yet why anyone would want to mirror a >design)
Actually, it's not a particularly good reason, since it would be easiest and best to do the flipping with the photoplots. I'd think a fabricator who wants to do what printers call "work and turn" would be set up to do this with very little effort, less effort than it would be for us to make a combined PCB file. It's like step and repeat, even if we do it ourselves: it is better to do the repeating in the gerber. (If you edit the PCB later, do you want to edit all 32 copies of the board? Do you want to deal with inner layer net assignment problems -- you would need to use *only* split planes, not the default plane assignment, Protel is not set up, in the photoplot routines, for multiple copies of a board, with some flipped. And I'd not want to see the added complexity; rather, giving us a tool to easily step and repeat and flip-combine photoplots is quite sufficient, I haven't investigated trying to do this with CAMtastic.) I produce a price list for my wife's business on our copy machine. The list is printed on 8.5 x 14 inch paper (a standard size in the U.S.). The final list size is 7 x 8.5, being half of the paper stock. The front and back are placed on the same side of a sheet of 8.5 x 14 paper, side by side (I tell the printer driver that the page size is 7 x 8.5, and I make a simple pasteup with the two pages -- I could set up printing to print the whole sheet at once, both sides together, but it has not been sufficient trouble to make the pasteup to bother). I then place this original on the copier as if I were copying an 8.5 x 14 sheet, which I am.... Then I take the copies and place them back in the paper feed. This is a copier which turns the paper over when it copies, so the flip is automatically done. I then copy again, exactly the same, and then cut apart the price lists. This is a very common technique in printing, where it saves plates and press set-up, one gets to print both sides of the sheet with only a single press set-up and plate. Printed circuits should work exactly the same way; as long as the stackup is symmetrical and the two images are placed so that turning the panel over backs up the original in exactly the correct register, the two boards, once cut apart, will be identical in every way. Any process that works on one side at a time will save one tooling and setup cost by using work and turn. Since normally boards are panelized anyway, this process simply needs a different panelization, with half the boards flipped. If the geometry of this is difficult for anyone, take a piece of paper. Fold the paper in half. Draw a shape (any closed curve or polygon) on one-half that paper. Most of us don't have light tables any more, so lay the paper on a window with light shining through and trace the outline that appears on the other half (at this point the other side of the folded paper) of the paper. You can then unfold the paper and write "TOP" within one shape and "BOTTOM" on the other. Put this drawing, unfolded, in a copier set to copy on the same size paper at 100%. Run a few copies. Leaving the original under the platen, put those copies into the paper feed tray, and copy them again. With some copiers you will have to turn the paper over for the second run. Normally, you would turn it around the axis of the fold line you made. If the two copies don't back each other up accurately, there is one of two problems: (1) the paper needs to be turned differently when it is put back into the copier, or (2) the copier is not accurate, which is normal. But in this case the two images should be close enough that you can see the idea. You should end up with a single sheet of paper from each copy which has two polygons on it which could be cut out to make two identical copies of the shape, printed both sides. Any part of the process which involves imaging or placing something on one side at a time will save a setup using this process, as long as both sides of the board can be treated identically. That's not necessarily true for all kinds of assembly, so at the point where the handling is not symmetrical, one would cut apart the panel along the axis of image symmetry, assuming that the "top" side has been placed all on one side of the panel and the "bottom" on the other. [EMAIL PROTECTED] Abdulrahman Lomax Easthampton, Massachusetts USA * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/[email protected] * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
