Electronics Forum | Fri Sep 12 08:01:55 EDT 2008 | davef
There is no standard. On the web, you can find shelf life estimates for various types of solderability protection on bare boards. These estimates won't translate directly to the storage of assembled boards, because assembled boards [and the solderabi
Electronics Forum | Mon Aug 30 14:32:52 EDT 2010 | davef
Steve: Yes, you shall bake prior to thermal cycling. You should be able to download J-033 from JEDEC [ http://www.jedec.org/standards-documents ]. You want "Paragraph 4 Drying." While it's aimed a component parts and not assemblies, J-033 is as goo
Electronics Forum | Fri Feb 01 14:49:52 EST 2013 | emeto
Thank you guys. You keep adding valuable information here. I think we will try to stick with the 3 times reflow(if we count the BGA repair as 2 reflows). However sometimes we will run the board second time through the oven(just flux the suspect part
Electronics Forum | Fri Oct 18 12:40:35 EDT 2013 | robertwillis
Back in the mists of time there were two papers on the use of Parylene Coating and the improved thermal cycling results in 1990. It was on LCCC then shortly after on BGA. Does anyone know of results of recent trials or have a copy of the BGA papers.
Electronics Forum | Sat Aug 03 03:28:16 EDT 2019 | alexeyzb
We use SNPb for such applications (PCBA for aircraft). We tried SAC305 but recieve no good quality, so now only SNPb. If you will find good solution - please write. Because now we have some problems with BGA - no SNPb balls. And need to reball (addit
Electronics Forum | Thu Sep 05 10:15:58 EDT 2019 | SMTA-Richard
There are multiple solder alloy options and we have tested many of them in a consortium project. There also are very specific challenges associated with testing using the -40/150 C profile. This is way too complicated to discuss in a chat room. Se
Electronics Forum | Fri Jul 06 08:10:50 EDT 2018 | davef
ACCELERATION FACTORS AND THERMAL CYCLING TEST EFFICIENCY FOR LEAD-FREE SN-AG-CU ASSEMBLIES [http://www.jpclech.com/CLECH_SMTAI2005_PAPER.pdf] Jean-Paul Clech EPSI Inc. Montclair, New-Jersey, USA jpclech@aol.com Paper (copyright EPSI Inc. © 2005) was
Electronics Forum | Mon Aug 10 12:58:04 EDT 2020 | SMTA-64386637
We have found Acrylic CC under QFNs is a failure mechanism in thermal cycling. The coating acts as a wedge and causes solder joint cracks. We do not coat QFNs. To enhance reliability we have the vias plugged with solder mask. This eliminates some
Electronics Forum | Tue May 27 10:34:30 EDT 2003 | davef
Much of the ability to survive rework or thermal excursions is dependent upon the fabrication materials. The board qualification criteria under the 55110 was designed around 5 thermal heat cycles. Consider reworking a BGA in this context. BGA i
Electronics Forum | Wed Jun 26 08:53:32 EDT 2002 | davef
We have not done a DOE on board warping. Consider: * How close the board gets to its Tg during the reflow cycle * Amount of copper on each side and the balance between the two * Thickness of the board * Overall length x width * Time at temperature
