Electronics Forum | Thu Feb 02 09:07:28 EST 2023 | charles_nguyen
Two types of land patterns used for surface mount pads are non-solder mask defined or NSMD pads and solder mask defined or SMD pads.Each type has its own advantages and disadvantages. There is a statement that SMD pad type may introduce stress concen
Electronics Forum | Fri Feb 17 19:23:05 EST 2023 | SMTA-64387083
Read the articles everyone else recommend. I haven't read of them but I will say this. A Solder Mask Defined pad is a copper flood that has much more thermal mass than a Non-Solder Mask Defined pad so it will heat and cool at a slower rate. I suspect
Electronics Forum | Mon Feb 06 17:58:16 EST 2023 | davef
The September 29, 2022 Express Newsletter [ https://smtnet.com/express/index.cfm?fuseaction=archives&issue=20220929 ] has papers on chip cracking
Electronics Forum | Wed Feb 08 09:43:08 EST 2023 | charles_nguyen
Thank you for the above information but what I want to talk about is the PCB design aspect. Should there be any warning about it in the DFM?
Electronics Forum | Thu Feb 02 10:10:20 EST 2023 | tommy_magyar
Perhaps google this, as you will find very interesting articles. For scientific explanation look up solder fatigue on Wikipedia with references added. A more in depth explanation you can find on the Digikey forum where you will find other people like
Electronics Forum | Wed Mar 17 14:59:53 EST 2004 | Claude_Couture
since there is a bit of humor in this thread, try drilling the pads from the opposite side of the pcb.
Electronics Forum | Mon Oct 13 19:04:47 EDT 2003 | davef
Aperture size should vary with the component [pitch]. That size should be the same a the pad size. So, generally pinching is not required. Indium discusses BGA apertures on their site [ http://www.indium.com ]
Electronics Forum | Fri Mar 19 10:06:22 EDT 2010 | karlo
Rework is typically done by heating the BGA to 170-180C to first scrape off the fillet. Then, heat to above reflow, and lift the BGA. Then, collapse the solder with heat and flux. Then, back down at 170-180C, scrape off the underfill from the boar
Electronics Forum | Sun Aug 10 21:57:25 EDT 2014 | cmchoue
Does IPC definition for "QFN Void Ration" ? Like IPC 7095 susgestion the BGA Void ratio.
Electronics Forum | Fri Aug 22 00:20:29 EDT 2008 | rameshr
Hai, In our process we are using the micro bga of size 13X13mm of pitch 0.45mm,after soldering process the bga found collapsed, we absorbed that the PCB land pattern of the BGA was not in array, uneven distribution of pads (area) & most of the pads
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