Okay a lot of you out there have a lot more experience with BGAs and micro
sized devices than I have, I wanted to see if any of you have heard of this
issue. I know that I have only heard the opposite until today.
What I was told today is that Linear Technology and some other Semi
technical articles are stating that for small vias (13mils or smaller), one
does not have to tent vias on BGAs or worry about vias in pads because the hole
is so small that it will not thieve solder from the pad/joint. Now this goes
against all I have ever heard because all the talk of BGAs has always concerned
themselves with solder thieving from the pads and tenting vias/dogbones to stop
this. Now my thinking is that maybe that is old school and only an issue on the
larger/older BGAs where one may be using larger vias. But with some of these
new microBGAs you would be very hard pressed to use anything larger than a 13
mil finished via hole. And with a hole this small it is smaller than most
solder paste balls and the surface tension of the solder may restrict solder
flowing into the hole when it is reflowed.
Comments? Anyone confirm or refute this claim?
Sincerely,
Brad Velander
Senior PCB Designer
Northern Airborne Technology
#14 - 1925 Kirschner Road,
Kelowna, BC, V1Y 4N7.
tel (250) 763-2329 ext. 225
fax (250) 762-3374
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