Oblong BGA Pads Instead of Round For 1st Row

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   In reference design special shape (narrow oblong instead of round) of a 1st row pads is applied. 
How often this trick is used? What is about soldering result for a volume production?
BGA has 0.46 pitch, without this trick 3 mils width/separation is required, with it 3.7 mils width/separation is acceptable.
These traces and pads are most complicated place in particular PCB design and defines fabrication requirements for a whole project.
Default pad size is a 10mils, oblong pad has 7 mils x 13 mils dimensions.
How it can be calculated for proper soldering? 
Is it possible to change size even more (6 mils x 14 mils) to get low-cost 4 mils width/separation requirement for fabrication?
Many thanks!

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toshas Members Profile Send Private Message Find Members Posts Add to Buddy List Advanced User Joined: 03 Jul 2017 Status: Offline Points: 71	Post Options Post Reply Quote toshas Report Post Thanks(0) Quote Reply Topic: Oblong BGA Pads Instead of Round For 1st Row Posted: 30 Sep 2021 at 10:41am
	In reference design special shape (narrow oblong instead of round) of a 1st row pads is applied. How often this trick is used? What is about soldering result for a volume production? BGA has 0.46 pitch, without this trick 3 mils width/separation is required, with it 3.7 mils width/separation is acceptable. These traces and pads are most complicated place in particular PCB design and defines fabrication requirements for a whole project. Default pad size is a 10mils, oblong pad has 7 mils x 13 mils dimensions. How it can be calculated for proper soldering? Is it possible to change size even more (6 mils x 14 mils) to get low-cost 4 mils width/separation requirement for fabrication? Many thanks!