Hi, Dr. Gil It depends on the service environment the assembly is expected to see. Usually the LGA soldered directly to the pads on the PWB is not able to withstand as many cycles to failure as the same package mounted with Pb90/Sn10 balls or interposer pins, which will help provide stress relief to accomodate the differences in thermal expansion between the PWB and the LGA package. So, it depends on the application and the material properties of the PWB and the component. A device that will see relatively little temperature cycling and little other shock or stresses may do very well with the LGA soldered directly to the PWB. On the other hand, if the assembly is going to see severe thermal cycling, you may wish to attach it with Pb90 balls or some other compliant pin technology to extend the time to failure of the solder joints. You would need to qualify this by building prototypes and cycling over time under the same conditions (or worst-case conditions) in order to determine mean time to failure. (My apologies to Doug Pauls for using the trademark phrase "it depends" twice without permission.) -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Zilber Gil Sent: Tuesday, January 10, 2006 11:56 AM To: [log in to unmask] Subject: [TN] LGA Package reliability Hello all, As more and more devices are coming in a LGA packaging format I am wondering regarding the reliability of the interconnect. I did not found a clear opinion and definite results in papers dealing with this issue. More of that, some companies sending the package as "BGA ready" (meant that you put later on a BGA solder balls) while other recommends to direct assemble the device. Even more confusing is the fact that some of the pads are rectangle while others are round. Does someone have more data regarding the reliability and process for this packaging type (assuming a device size of 15x15 mm)? Thanks and happy New Year, Dr. Gil Zilber Elta system Ltd. The information contained in this communication is proprietary to Israel Aircraft Industries Ltd. and/or third parties, may contain confidential or privileged information, and is intended only for the use of the intended addressee thereof. If you are not the intended addressee, please be aware that any use, disclosure, distribution and/or copying of this communication is strictly prohibited. If you receive this communication in error, please notify the sender immediately and delete it from your computer. Thank you. This message is processed by the PrivaWall Email Security Server. --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 1.8e 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 -----------------------------------------------------