John , Your saying is applicable on the actual board, because it's not hanging in edge rails, but is rather screwed down by means of plastic towers in the middle! The board designer is one of the biggest, so it's a surprise to me. They sell the board type to many customers, one of which gets electrical disrupts on many solder joints along the one side faced towards the card edge, and none along the other three package sides. Your words give me the idea that something happens when the board is shaking in this very vibrating and tough environment. Many thanks. Inge -----Ursprungligt meddelande----- Från: TechNet [mailto:[log in to unmask]] För John Maxwell Skickat: den 16 april 2007 19:36 Till: [log in to unmask] Ämne: Re: [TN] Placement of large flatpacks and BGAs close to board edge Inge, This is because board flexure or deformation is typically greatest at corners and along board edges. The same rule should be applied to chip capacitors as well. Regards, John Maxwell >Dear collegues, > >I have heard of a thumb rule, never place them along and close to the >edge. Hence, we place them (when suitable) in the center. I have >forgotten why this rule. Was it because of vibration nodes, warpage >during soldering, tempcycle issues or what? Is there a IPC standard or >other reference? > >Inge > > > --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/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 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/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 -----------------------------------------------------