Hi Darcy... One of the ways to reduce mechanical stress in a board is to make more mounting supports. In high vibration environments you may need to keep all the mounting supports at 3 to 4 inches apart from each other in any direction to keep the board as rigid as possible to it's mounting plate.
Second option is to use vibration dampening mounts. Third might be to add a board stiffener or two... fourth might be looking at thicker material and or metal core type boards... The costs go up with each successive solution... Here are some shock mount vendor sites http://www.parvus.com/ http://www.wmberg.com/prshockabsorbing.html https://sdp-si.com/ But if you can just mount the board to a sheet metal plate with standoffs that are 3 inches apart you will be able to withstand very broad frequency high vibration. (Except at the resonant frequency that is... ) The whole trick to vib control is making sure the resonance is out of the spectrum of the frequencies your board will experience. There is a very good book out there on Vibration by Dave Steinburg... Called "Vibration Analysis for Electronic Equipment". I'm sure it's available from Amazon or some other bookseller... Chapter six covers Printed Circuit Boards and Flat plates... Hope that helps some... Bill Brooks - KG6VVP PCB Design Engineer , C.I.D.+, C.I.I. Tel: (760)597-1500 Ext 3772 Fax: (760)597-1510 e-mail:[EMAIL PROTECTED] http://www.dtwc.com http://pcbwizards.com -----Original Message----- From: Darcy Davis [mailto:[EMAIL PROTECTED] Sent: Thursday, April 14, 2005 7:50 AM To: PEDA (E-mail) Subject: [PEDA] Mechanical Stresses on PCBs Hey Guys, One of the latest issues we've run across (while trying to balance weight, size, money) in a current design is that there is some potential for mechanical stresses to be induced into the PCBs in the end user product. This causes a couple issues. The first is the obvious solder joint integrity and the possibility of damaging components or traces on each PCB. The second is the alignment of a board to board connector (Hirose DF12 series) between two PCBs. My first gut reaction is "absolutely no stresses are acceptable in the PCB," but since we're balancing the above objectives, I thought I'd throw some questions out. 1) Has anybody got an opinion or has read some article on allowable stress or flexure of populated PCBs? 2) Have you seen any sort of flexible mount that could be used to "float" the PCBs. Currently we're using 3mm screws to secure the PCBs so we're looking for a solution that would be the same order of magnitude in size (ie. Chev 454 motor mounts are too big!) Thanks for any suggestions you may have. Darcy Davis Design Engineer, Dynastream Innovations, Inc. ____________________________________________________________ You are subscribed to the PEDA discussion forum To Post messages: mailto:[email protected] Unsubscribe and Other Options: http://techservinc.com/mailman/listinfo/peda_techservinc.com Browse or Search Old Archives (2001-2004): http://www.mail-archive.com/[email protected] Browse or Search Current Archives (2004-Current): http://www.mail-archive.com/[email protected] ____________________________________________________________ You are subscribed to the PEDA discussion forum To Post messages: mailto:[email protected] Unsubscribe and Other Options: http://techservinc.com/mailman/listinfo/peda_techservinc.com Browse or Search Old Archives (2001-2004): http://www.mail-archive.com/[email protected] Browse or Search Current Archives (2004-Current): http://www.mail-archive.com/[email protected]
