Electronics Forum | Fri Dec 10 08:42:37 EST 2004 | mattkehoe
We had some bad experiences trying to work with soldermask defined BGA pads. If the opening in the soldermask is right to the edge of the copper/pad without a space it can leave reside on the pad and nothing will stick to it. See http://www.sipad.com
Electronics Forum | Fri Jan 22 16:03:17 EST 2021 | SMTA-64387124
Does anyone see any issues in mixing SMD and NSMD pads within one BGA footprint. We have high current pads which we want to make SMD and the other signal pads to be NSMD
Electronics Forum | Thu Dec 09 07:46:42 EST 2004 | davef
We did this for BGA pads, but have not thought about other types. So, this may or may not apply for those. Pad defined by:||Advantages||Disadvantages Non-solder mask||No point-of-stress concentration at edge mask and solder ball||Smaller pads have
Electronics Forum | Fri May 02 09:37:23 EDT 2003 | Jerry Magera
Via in pad is the most efficient use of space. Blind via seems to be blamed for this. Cross-sections (send me some) will probably show a void still existing in the via or spherical voids aligned near the component pad side. One can estimate the vo
Electronics Forum | Fri Oct 15 10:35:44 EDT 2004 | russ
sounds like you have a very thin layer of mask on some pads to me. Russ
Electronics Forum | Thu Oct 14 17:14:39 EDT 2004 | mattkehoe
We are experiencing a problem with soldermask defined BGA pads not accepting solder during the reflow process. The paste is there when the boards come off the printer but after reflow, no paste. Some other pads in the same pattern are fine. Here is t
Electronics Forum | Fri Oct 15 10:23:48 EDT 2004 | mrmaint
Matt, are there any discoloration of the pads on the raw boards. i have seen what we refer to as gray pads. Ran into this in the past and it turned out to be a problem at the board house with one of their dipping tanks. The proper levels for the proc
Electronics Forum | Fri Oct 15 10:38:42 EDT 2004 | mattkehoe
Thats what I was thinking especially because the pads are not round, they have jagged edges which to me indicates some kind of development issue. mk
Electronics Forum | Wed Oct 20 06:23:54 EDT 2004 | C Lampron
Hi Matt, Sounds like the HASL may be to thin on some pads and you're getting copper migration. If this is the case, and the solder paste is printing, I would asume you would see some solder balls under the BGA at X-Ray or incosistancies in ball size
Electronics Forum | Fri Oct 15 09:11:39 EDT 2004 | mattkehoe
Hi Justin, Thanks for the feedback. We are inspecting with the naked eye. Most of what we do are prototype quantities, in this case 6 pcs, so AOI or measurement equipment has never seemed justified. The release looked uniform during the printing a
