Electronics Forum | Fri Mar 04 18:28:21 EST 2011 | hegemon
First, I would inspect for lack of solder bridges from the center slug to the outside leads. I would then look for evidence that the solder paste has reflowed beneath the component, without leaving too much void percentage. Typically we allow up
Electronics Forum | Fri Jul 20 13:50:22 EDT 2018 | vchauhan
This question is regarding stencil design: I am having voids under QFN TI P/N LMZ20502SILT. I have attached component pic. Signal pin is 18X16 mils. Center pads are 31 mil sq. Initially I had stencil done with one mil per side reduction on signal pad
Electronics Forum | Fri Jul 13 18:25:09 EDT 2007 | seankim10
It sounds like more has to do with plating. you may also check out the voiding issue especially if you have new FAB or the supplier. I had problems with a RF chip in QFN package due to insufficient grounding that voiding caused. This ground is often
Electronics Forum | Tue Aug 31 04:05:23 EDT 2010 | arjan
Hi Mark, Thanks for your responce! The stencil thickness and especially the reduction of 45% are not recommend by LT, did you came to this combination experimentally? We never have the illusion to produce voiding free, but now its around the accepta
Electronics Forum | Thu Jun 10 16:42:11 EDT 2010 | daxman
Hi Muarty, We've had a lot of experience with QFN's now. Several years ago we started testing various design methods of the via arrays as well as paste apertures to cover the arrays. There has been some time that has passed now since these packages
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
Electronics Forum | Thu Sep 02 16:55:31 EDT 2010 | markgray
I ment LF318. We have a power supply board that has 3 different types of these LGA's and i have had great success with the reductions and stencil thickness mentioned. We had to go with 4 mil stencil due to the consideration of the other large compone
Electronics Forum | Mon Aug 30 06:47:18 EDT 2010 | arjan
We having issues installing the Linear Tech LTM8023. We have different soldering results in our PBfree testruns. The voiding and solderball rate is not stable (random positions and sizes). The pcb's (gold finish)are prebaked, the LGA's are stored in
Electronics Forum | Mon Jul 05 03:53:36 EDT 2004 | johnwnz
Hey, this is something that I've looked at and published a paper on back in 2003 at Apex, actually pert of one, the other part was lookign at how effective X-ray systems (lamanography systems) were at detecting & measuring BGA void size accuratly (co
Electronics Forum | Tue Nov 09 13:12:26 EST 1999 | Dave F
Steve: Sure, but let's figure it out for you!!! ;-) Here�s some sample calculations. Your results may vary, void where prohibited, etc 20 PITCH: Pinched aperture volume: 0.010"X0.050"X0.005" = 2.5 uin^3 Zippered aperture volume: (0.015"X~0.5)
