It can also contribute to "tombstoning" Denis Lefebvre, CID+ PCB Designer Finisar Corporation (408)542-3832 -----Original Message----- From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of Brand, Rodney Sent: Thursday, April 30, 2009 10:06 AM To: [log in to unmask] Subject: Re: [DC] Traces and vias under components With a capacitor the copper in the middle covered with solder mask can contact the body acting as a fulcrum and causing the part to change value or fail. -----Original Message----- From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of S. Roy Sent: Thursday, April 30, 2009 1:00 PM To: [log in to unmask] Subject: Re: [DC] Traces and vias under components Hello everyone, Stupid question but... An Engineer would like to know why it is such a bad idea to run traces between the pads of the same component, i.e., a 1206 resistor or cap. I know I shouldn't do it, but I can't put my finger on the spec that supports my distain for running these traces. Can someone steer me in the right direction, please? Thanks... Respectfully, Steven D. Roy PCB Designer Audio Authority Corp. 2048 Mercer Road Lexington, KY 40511-1071 (859) 233-4599 X-159 [log in to unmask] -----Original Message----- From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of Andy Kowalewski Sent: Wednesday, March 18, 2009 6:21 PM To: [log in to unmask] Subject: Re: Traces and vias under components You can almost guarantee that the board they had trouble with had open vias under the components, and wave soldering filled the vias and made a little dome on the top side, ready to make short circuits to any metal bodies. Properly tenting thye vias would fix that problem. Cheers... Andy Kowalewski 0424 432 235 -----Original Message----- From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of wheels Sent: 2009 03 19 01:44 To: [log in to unmask] Subject: [DC] Traces and vias under components Guys, We have a customer which we are designing a mostly SMT board for that requires all traces and vias not to be under components. This would also include any planes being under the components. I guess in the past they had a board designed by some else that had a shorting problem with traced and vias under the components. They are insistence that this is the way it has to be. Has anyone else had experience with this sort of demands? This is not for space, military, high voltage, high vibration or a medical application. Can anyone think of anything we could tell they to change their mind? Thank you, wheels ------------------------------------------------------------------------ ---- ----- 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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To temporarily stop/(restart) delivery of DesignerCouncil send: SET DesignerCouncil NOMAIL/(MAIL) Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ---------------------------------------------------------------------------------