Electronics Forum | Tue Sep 14 17:06:25 EDT 2010 | asksmt
Hi All, I have designed 4 Layer PCB with one 28 pin QFN PKG. I have got complaint from Production that the pads which connected to thermal pads (gnd) thru trace is bridging with solder and because of this bridge, pins are not getting soldered prope
Electronics Forum | Wed Jan 15 11:53:40 EST 2020 | avillaro2020
As far as the large thermal gradient I have on my thick and thermal heavy board, I've done quite a bit to minimize the gradient but not successful. it's like one pad is connected to a signal while the other pad is connected to ground, you can't bring
Electronics Forum | Tue Mar 28 08:29:04 EST 2006 | davef
Pad design - Standard IPC 20 pitch QFP Thermal pad design - Layout the thermal pad 0mm to 0.15mm larger per side (0mm to 0.30mm larger overall) than the exposed die pad on the package. �Larger than�, as opposed to the same size, is preferred. Obvio
Electronics Forum | Wed Oct 05 15:03:40 EDT 2005 | Amol
depends on what you want evaluated! you can thermal cycle the BGAs and the examine the x-sections to determine failure modes at different stages of thermal cycles. you can do a stress test and corelate the # of thermal cycles with the microstructu
Electronics Forum | Thu Jun 01 09:31:26 EDT 2006 | marc
All data loggers will be warmer at the higher lead free temps. Only two ways around this... better thermal barriers or fans after the profile to cool it down. Some places do not allow fans on the production floor due to static electricity, in that
Electronics Forum | Fri Jan 12 19:49:07 EST 2007 | stepheniii
I think she might be more on track about the air flow. I would think they not only have thermal mass but also emit thermal energy well which would add to the dificutly of removing them. I think a Dpak would have more local thermal mass than the shie
Electronics Forum | Tue Jul 15 18:05:48 EDT 2008 | arminski
How many times do you measure your oven's profile? I have seen companies running a thermal profile prior to every run of their products into the oven. But if you are in a low to medium volume - high mix category what is the best frequency of measurem
Electronics Forum | Tue Dec 28 03:59:06 EST 2010 | riscy00
I'm investigating heat transfer by 1st order approximation between PCB and ambient air via encapsulate material (epoxy or gel or silicone), they have thermal conductivity of 0.2W/C but it hard to find specific heat capacity and density. Has anyone
Electronics Forum | Thu Mar 17 10:06:09 EDT 2011 | dyoungquist
Strange indeed. We use a Q18 and have never seen this. Is it sweating inside the thermal barrier case, i.e. you put it in the case dry and it is wet when you take it out of the case? Maybe its actually coming from the inside of your thermal barrie
Electronics Forum | Sun May 19 23:38:57 EDT 2013 | shrikant_borkar
We are EMS. Later revisions and Other models are get Modified. Now we have some remain Stock of Pcbs abd there end also. We have taken trial with Reduction in Apparatuses. But even small amount of solder paste at thermal Pad is causing QFN lift up.
