Electronics Forum | Fri Sep 24 09:49:53 EDT 1999 | C.K.
Hi Folks: We've been having bridging problems on our fine-pitch QFP's, despite thorough inspection of paste height, volume, and placement accuracies....profiles look good also. The bridging is happening after coming out of reflow...one last thing t
Electronics Forum | Fri Sep 17 03:03:29 EDT 2010 | grahamcooper22
Hi Gani, looking at the HASL icture and the poor wetting of the solder over the pads I would imagine that the HASL coating is very thin on the pads and in actual fact isn't 'solder' but is tin /copper intemetallic and this has poor solderability. It
Electronics Forum | Wed Oct 03 09:56:51 EDT 2001 | Claude Tremblay
Hello everyone We have a QFP-308 (0.20" pitch)on a board and we have a lot of opens after reflow. We checked our profil by installing thermocouples on the pads of the component and everythings seems OK. We checked the coplanarity of the leads and it
Electronics Forum | Fri Sep 24 10:57:18 EDT 1999 | Earl Moon
| Hi Folks: | | We've been having bridging problems on our fine-pitch QFP's, despite thorough inspection of paste height, volume, and placement accuracies....profiles look good also. | | The bridging is happening after coming out of reflow...one la
Electronics Forum | Tue May 31 10:44:16 EDT 2005 | Scott B
We have found that when the HASL thickness is less than 5 microns the tin in the HASL reacts with the copper leaving a SnCu surface with poor solderability and microscopic grainy Pb islands. The IPC does not specify minimum HASL thickness but we now
Electronics Forum | Mon Aug 23 14:09:56 EDT 2010 | davef
Similar to Coop's comments, above ... Bridging: * Mis-placement: misplaced components, high placement force mushrooms paste * Too much paste: HASL thickness, lead finish, poor underside support, poor underside wipe frequency, printing with too lar
Electronics Forum | Wed Aug 09 08:46:01 EDT 2017 | stivais
I agree. Just thinking.. could it be copper plating issue as well? anyway, would be interesting to see some photos. Sounds like solder (from HASL process, wave or even poorly washed SMT solder paste) to me.
Electronics Forum | Tue Sep 14 14:22:11 EDT 2010 | grahamcooper22
If the HASL was poor quality and very thin you would find this defect....but you would expect to see it on more pads also. Also, you'd expect to see your solder from your solder paste either dewetted on the pad or reflowed onto the BGA sphere making
Electronics Forum | Wed Oct 03 17:07:52 EDT 2001 | davef
We have had soldering problems with fine pitch QFP in the past [and probably will in the future]. Several questions leap to mind: * When you took your profile on the component pads, do you profile on the pads that did not solder well? * When you say
Electronics Forum | Sat Jul 28 08:37:52 EDT 2007 | davef
There is no good choice. Board Finishes: Industrial/Battelle Class 3 Environment [Reliability Knowledge Gaps: For use of Pb-free solders in High Reliability Applications, J Smetana, iNEMI Availability of SnPb-Compatible BGAs Workshop, March 1, 2007,
