Gary, I would recommend sending the panel design out to your board vendor and having them make a blank .062 panel board with the V-scores in it for testing the panel concept. Web thickness vs. groove depth is divided up typically as 1/3, 1/3, 1/3 of the board thickness. But each design is different, and not all shops do V-scoring exactly the same... some use a diamond wheel cutter and some use routing tools... check with them before adopting a strategy and see what works best for your assemblers. V-scoring can be a real board weakening operation that can allow the board to sag when put through a wave soldering machine, or Pick and Place holders, or even hand stuffing operation with board supports... sometimes it can be hard to predict just how a scoring pattern can affect the panel stiffness and the ease of breaking out single boards from the panel... Our vendor made a blank panel for us for free to test out a routing design and make sure that the boards would not separate when they weren't supposed to and that the combination of the number of boards and V-scores didn't make the board too weak. This exercise can save you on board spins and headaches in prototyping... You may find that making a smaller panel is more to your liking when handling during assembly and test based upon the size of the panel you are proposing and the number of v-scores that will be required to have 120 boards in it... Also, take into account the board manufacturers panel size and the need for some waste area around the perimeter of the panel... How many of your assembly panels will fit into an 18X24 inch panel? We chose to make our assembly panels 8X11 so that they will not be throwing away board material at the manufacturer that we pay for but would not get boards out of... That size gets us 4 of our assembly panels in one of the board manufacturer's panels. Sometimes we make 1/2 panels ( 4when we do small boards like you are doing to make them stiffer and I design supports into the panel to help with rigidity as well. Panel design takes some careful thought, and planning... Get to know your assembly people well and ask questions... it will help your product be more cost effective and less trouble to build. Good Luck with it... :) Best regards, Bill Brooks, CID+ -----Original Message----- From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of Gary M. Koven Sent: Thursday, August 16, 2007 12:05 PM To: [log in to unmask] Subject: [DC] V-scoring and web thickness I'm preparing a panel layout drawing. For purposes of this post, all dimensions are in inches. Material is 0.062 FR-4 Panel size is 12.000 X 8.500 Board size is 1.000 x 0.625, 120 boards per panel I want to v-score these boards for "easy manual singulation" and would like to put a note on drawing to make sure the cuts are deep enough. Now then, READILY AVAILABLE REFERENCES 1) Apart from IPC-2222 Table 5 general parameters there appears to be no other official IPC publications describing preferred web thicknesses. 2a) The best Internet reference I've been able to find is here: http://www.tkb-4u.com/articles/other/vscore/vscore.php 2b) According to the matrix within this article, for a panel 10 to 15 inches long and individual PCB 1.0 long, I should recommend 0.010 web thickness. 3) According to the LISTSERV archives, in message 006509 back in 2001, my old colleague Ed Valentine (now retired) recommended 0.012 web thickness for easy manual breakaway. CONCLUSION So if I didn't know any better and if nobody answers this, I'd end up with a drawing note something like this: "V-SCORE TO FINAL WEB THICKNESS OF 0.012" +/- 0.002" USING 30 DEGREE CUTTERS" I'm going to call some fab folk to get their take, but meanwhile, your assistance here is kindly appreciated. Thanks and Best Regards, ---------------------------- Gary M. Koven, C.I.D. Dynazign, Inc. Charlotte, NC, USA 704.405.1234 Veteran of the Marsh School ------------------------------------------------------------------------ --------- DesignerCouncil Mail List provided as a free service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF DesignerCouncil. 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