The BQ27220YZFR is a BGA package with a fine-pitch of 0.5 mm between solder balls. According to the 4 Layer 35µm ENIG design rules, the minimum spacing between copper is 125 µm, with a minimum track width of also 125 µm. With that, it doesn’t seem possible to route the IC in accordance with the design rules.
Can you suggest a suitable way so that I can use the part, and don’t have to have my PCBs manufactured and assembled in China?
Hi @Arvid1,
I’m afraid that’s going to be difficult. What minimum spacing and/or track would you need to route to the GND pad? Generally, for assembly projects, you have the option to send us a custom request via our contact form. Often, a solution can be found by manufacturing the PCBs in a special/custom production run. Alternatively, you could consider capped vias here. However, these are also non-standard and would need to be requested individually.
I assume there is no option to use a larger part with lower requirements? 
Kind regards,
Manuel
Hey,
thanks for the reply. Comparing a few manufacturers, I think the most feasible way of routing out the 0.5 mm BGA is with via-in-pad. A via with a 0.2 mm hole, and 0.35 mm diameter. Placing that in the middle of the pad gives 0.2 mm spacing between the copper of the pad and the via. This seems to be, at a slightly higher price, possible by some manufacturers.
My testing revealed that routing out would require 0.09 mm / 3 mil tracks with 0.051 mm / 2 mil spacing of the track to the SMD pad (when not making the pad size any smaller; however, the pad size is already at the minimum specified by Ti).
When changing the pad size to 0.2 mm (down from 0.25 mm), I can route out with a 0.1 mm track, and 0.1 mm spacing between track & pad.
I agree, it would be better to use a different part. I’ll get back to the drawing board, I could probably get away without a BMS IC in the first place.
Alright, thank you for sharing the information you found @Arvid1 (:
I’ll mark this question as answered, if another one comes up during the process, feel free to create a new one.
