X-Ray inspection (at an angle, not top down) is tricky as the joints have no appreciable height. Absolutely no visual inspection is possible (unlike most BGAs, where you can see at least the outermost row). We also observed voiding under the prototype LGAs we assembled. I made sure that the board design was per the manufacturer spec and printed solder 1:1 with the pad and using our standard 2 mil reduction (1 mil on each dimension). Both soldered about the same, no difference in voiding. Regards, Amol -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Inge Sent: Friday, June 19, 2009 9:22 AM To: [log in to unmask] Subject: Re: [TN] LGA assembly question Hi Bev, LGAs have higher standoff (solder pad contra board pad) and have a little better signal integrity. If QFNs have any parameters better than LGA, I don't know. Normally, we do not make any other difference between them than solder amount. /Inge ----- Original Message ----- From: "Bev Christian" <[log in to unmask]> To: <[log in to unmask]> Sent: Friday, June 19, 2009 3:08 PM Subject: Re: [TN] LGA assembly question Sylvain, Please enlighten us as to your understanding of the differences between a QFN and an LGA. Bev RIM -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Sylvain Kaufmann Sent: Friday, June 19, 2009 9:06 AM To: [log in to unmask] Subject: [TN] LGA assembly question Dear Technetters, Our assembly workshop has to assemble 4 prototype boards where LGA packages with 133 connections are used. I allready worked with BGAs or QFNs but never with LGA packages and I am concerned about shorts/open that could occur. Provided that I cannot run tests and conditions are as followed: - ENIG surface finish boards - Vapor phase reflow soldering - Pick and Place machine - Leadfree or lead containing solder can be used Would some of you be kind enough to share experiences/advices so that we would have little chances to successfuly assemble these boards? Thank you in advance for your help. S. Kaufmann ************************************************************ Sylvain Kaufmann CERN / European laboratory for particle physics Site de Meyrin 1211 Geneva 23 Switzerland Dpt: EN-ICE-DEM (int mail J06600) Phone: +41 22 767 37 02 Fax: +41 22 766 87 77 E-mail: [log in to unmask] Web: www.cern.ch http://cern.ch/dem ************************************************************ --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------------------------------------------- This transmission (including any attachments) may contain confidential information, privileged material (including material protected by the solicitor-client or other applicable privileges), or constitute non-public information. 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