Agree. Want to know how much distortion could one expect. 20, 30, 50 um? Anil On 31 Dec 2014 01:13, <[log in to unmask]> wrote: > Anil, > > FR-4 is composed of several layers of epoxy coated fiberglass fabric. > > The fabric has a warp and weft not unlike cloth. > > When the material is coated with the "B" stage epoxy it is subjected to > strains from the conveyor. > When the layers are added between copper there may be as many as three > different fiberglass fabrics, all will have different strains. > Heat up and cooling rates from the pressing or lamination cause additional > strains to be applied. > > Movement during your processing are a product of the fabric, for instance > the thicker glass (ie 7628) moves less, the thinner and higher resin > content fabrics move more. > > There is no one standard for movement. Work with your suppler technical > support to find the best dimensional product but this may be a tradeoff for > other factors. > > hope this helps, > > Chuck > ------------------------------ > > *Charles W. Brummer* | 3M Manufacturing Engineer > 3M Electronic Solutions Division > 3M Canoga Park, 8357 Canoga Ave. | Canoga Park, CA 91304 > Office: 818 734 4930 > *[log in to unmask]* <[log in to unmask]> | *www.3M.com* > <http://www.3m.com/> > > > This message (including any attachments) may contain material, non-public > information or proprietary information and is for the intended recipients > only. If you are not the intended recipient, you should notify the sender > and delete this message. Any disclosure, copying, or use of this > information is strictly prohibited and may subject you to legal liability. > > > > From: "Anil Kher" <[log in to unmask]> > To: <[log in to unmask]> > Date: 12/30/2014 12:33 AM > Subject: [TN] Fr4 panel distortion > Sent by: TechNet <[log in to unmask]> > ------------------------------ > > > > We have yield issues in production of 500 mm size panels in pattern to hole > alignment within 50 microns. > Never thought fr4 panel will distort. > Can anyone guide me on distortion of panel - 0.2 and 0.4 mm thick h/h > Thanks a lot > Anil Kher > > > ______________________________________________________________________ > This email has been scanned by the Symantec Email Security.cloud service. > For more information please contact helpdesk at x2960 or [log in to unmask] > ______________________________________________________________________ > This message has been scanned and no issues discovered. > > To report this email as SPAM, please forward it to [log in to unmask] > > ______________________________________________________________________ This email has been scanned by the Symantec Email Security.cloud service. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________