Electronics Forum | Wed Mar 15 04:36:16 EDT 2017 | Rob
@ Sr.Tech, Any voiding means that the part of the package under the void is not forming a solid thermal interface with the PCB, therefore it's heatsinking capability is reduced. With the drive for smaller packages with higher power handling capabil
Electronics Forum | Sat May 18 10:21:09 EDT 2013 | davef
isd.jww: Comments are: * Current thinking has flux volatiles being the major contributor to voiding, not scavanging by via * I have no reason to think that 0.3mm via won't gladly accept solder. Plug them, if that's a concern. * If your concern is ina
Electronics Forum | Thu Oct 26 10:29:03 EDT 2006 | Mike
First, Voiding under thermal pad is unavoidable(pardon the pun), unless you can find a way to add sufficient amount of solder paste to cover the area, and match that solder volume on your terminal leads. I build HVM qty's of "QFN" components w/ therm
Electronics Forum | Mon Apr 16 16:24:20 EDT 2018 | slthomas
Amazingly enough, every one of these held fast where we placed them with a paste brick sized 1:1 with the thermal pad, no sectioning. Yes, there were voids, but we can live with that in this application.
Electronics Forum | Fri Jul 27 09:47:20 EDT 2018 | davef
Adding to Rob's suggestions ... One of the theories about voiding in thermal / ground pads of BTC is: Solder starts melting at the edge of the pad and moves inward towards the center of the solder mass. This traps flux volatilizes. So, there needs t
Electronics Forum | Thu Aug 10 11:24:18 EDT 2017 | dleeper
The exposed metallization on the sides of the QFN probably aren't tinned and therefore not expected to have solder wetted to them. If previous parts formed nice toe filets, it might just be that those parts were fresher and the exposed metal did not
Electronics Forum | Tue Aug 14 08:19:45 EDT 2018 | buckcho
Hello, other colleagues gave you valid ideas. I found it helpful if i reduce the size of the cooling openings. I would suggest making the four big square into very small many diamonds. This would maybe decrease your voiding with 2-4 percent. Btw how
Electronics Forum | Wed May 22 19:10:47 EDT 2013 | anvil1021
We do a lot of these devices and I guess I am not familiar the term "Dry Solder". The QFN device is not designed to have a drain hole, but needs to have thermal vias to control heat in most cases. We have used every possible gnd pad design and modifi
Electronics Forum | Thu Mar 16 03:45:51 EDT 2017 | rob
It's the same thermal issue whether it's a die or package. It's different if it is just a signal trace, but if it's a heatsink pad (LED, FET, Motor driver, PSU IC etc). I think the voiding issue boils down to what the part is actually doing. The or
Electronics Forum | Wed Mar 15 08:18:29 EDT 2017 | rob
It's well documented in higher power semiconductors where thermal interface materials are used, such as SIL pads, thermal grease etc. There are a couple of papers on the effects of voiding on MOSFET performance, but I haven't got around to reading
COT specializes in high quality SMT nozzles and consumables for pick and place machines. We provide special engineering design service of custom nozzles for those unique and odd components.
2481 Hilton Drive
Gainesville, GA USA
Phone: (770) 538-0411
.gif)
