S3 device package

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Jack
Posts: 17
Joined: Tue May 19, 2020 10:03 am

Hello,

I found the package of S3 device on QuickFeather is QFN, it's different from the WLCSP and BGA package on S3 datasheet available on Quicklogic website. Could you explain the difference between those? Is there a datasheet for QFN package?

Thanks
Jack
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tutatis7
Posts: 10
Joined: Mon May 18, 2020 1:20 am

Hi Jack,

So the QFN package is only available on the QuickFeather and it was built in limited quantities so is not available for purchase. The information for this package should be available in the latest S3 datasheet or in the QuickFeather Github page.

So, for new designs, users should use either the BGA or the WLCSP packages for actual production.

Thanks
tnt
Posts: 16
Joined: Fri Jun 05, 2020 5:21 am

Which is a bit of a shame because it's a very convenient package for prototyping / experimenting.

0.4mm pitch as the "largest" pitch package is not great for OSHW devices you'd want people to be able and reproduce. No way to do that in common batch prototype PCB providers. 0.8 mm pitch (possibly 0.65) would be doable.
Jack
Posts: 17
Joined: Tue May 19, 2020 10:03 am

Yes, 0.35mm and 0.4mm pitch is OK for smartphone devices, but difficult for IoT applications. It requires very high level of production capability.
mwang
Posts: 16
Joined: Thu Jun 11, 2020 2:07 am

Unfortunately, our assembly partner EOLd the package after we were very far down the path with QuickFeather so we cannot support volume on the current QFN package used by QuickFeather. That being said, we are fully committed to providing a complete platform for the open source community, one element being a package that works for OSHW devices. One package lost is another package’s gain, so let’s discuss what would make a killer package for the OSHW world... type (QFN, BGA, QFP, etc), size, pitch, number of I/Os, etc. In fact, in the spirit of being open, we might just put this question out to the community so that we can get more input on what would make the most sense. Stay tuned.
tnt
Posts: 16
Joined: Fri Jun 05, 2020 5:21 am

I'd definitely go for QFN or BGA. BGA really isn't that much of an obstacle especially when you go for larger pitch like 0.8 or 1mm.

For QFN I actually think 64 with .5 mm pitch is pretty perfect. Good compromise between the chip size and the number of IOs. It's easy to deal with/break out on cheap PCB processes. (No need for HDI / blind or buried vias / 6/6 rules are fine).

For BGA, 64 ball with 0.8mm pitch would provide basically the same thing in a slightly smaller package. Pitch is large enough to easily stick vias between pads for easy breakout .

I would definitely avoid QFP, it's really no easier to deal with than QFN and takes more space.
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