Electronics Forum | Sat Jun 05 13:38:22 EDT 2021 | ppcbs
For Linear Tech LGA's we solder bump the LGA using a .30mm solder ball then reflow with a tacky flux. This will provide a void free solder joint and adds a little height to the solder joint in case you use a flux that you want to clean from under th
Electronics Forum | Thu Oct 25 13:35:47 EDT 2012 | davef
Here's a paper that may help http://www.ipcoutlook.org/pdf/assembly_challenges_bottom_terminated_ipc.pdf Temperature Impact * Profile didn’t have a significant impact on voiding. * Voids slightly increased with higher temperature. Reflow Atmosp
Electronics Forum | Sat Mar 29 08:38:28 EST 2003 | davef
Iman When you talk about your profile, can we assume you're measuring it on the pads of LGA? Profile the solder paste reflow by placing a thermal couple under the component pad, similar to a BGA. On a slight tangent, as with soldering BGA, paste
Electronics Forum | Thu May 08 19:52:40 EDT 2014 | hegemon
There are many different style LGA packages, but don't sweat it. Stick with the manufacturers recommendations for PWB pad geometry for a start. Voiding can be reduced by careful profiling, and also by pre-tinning the devices. QFN style packages can b
Electronics Forum | Fri Nov 23 06:34:43 EST 2012 | bandjwet
With all of the various techniques available for LGA rework including but not limited to: Bumping the part using a polyimide stencil http://www.solder.net/products/stencilmate Bumping the part using a metal fixture or http://www.finetech.de/advance
Electronics Forum | Fri Nov 13 06:56:37 EST 2009 | CL
Good Morning, The customer is looking for void free connections. They had never specified an acceptable percentage. We are reacting to the test yield. Our yield has averaged 50%. We do not test the product so we rely on feeback from the customer. Us
Electronics Forum | Wed May 20 17:18:09 EDT 2009 | daxman
Just out of curiosity, how are you or anyone else determining a defect? Last I checked, IPC had no criteria yet for solder defects for QFN components. Has this changed? Biggest problems we see are voids which our x-ray shows a lot of. Our problems
Electronics Forum | Mon Jan 19 05:02:07 EST 2015 | gertjannus
I've some troubles with LGAs components. i try to create void free results. so far i have no problems with dpacks, i think i do something wrong with the vacuum time. The padcoverage of my lga is very bad the vacuum creates solderballs under the compo
Electronics Forum | Wed May 20 17:56:51 EDT 2009 | dyoungquist
I have attached a pdf showing the dimensions for the QFN we placed. First, The pins on the part are not only on the bottom side but also wrap around to come up each of the 4 sides of the part as shown in the side view in the attached pdf. This i
Electronics Forum | Fri Jan 18 12:34:14 EST 2013 | duchoang
Yes, I have. think I have pretty good reflow profile. We use Lead-Free,No-Clean,SAC305 Solder Paste. The problem is at LGA design.The pad size is alot bigger than BGA. They are totally flat and do not have balls/spheres which melted and collapsed thr
