@laptop2d I just saw your rant about companies not wanting to share their datasheets. I can empathize. We're using developing a product strictly for Motorola and they spec'd a particular processor that isn't usually spec'd for our product we're developing. We respun the board to meet the requirements they wanted which was no problem. The COM Express board that Motorola wanted was only sold by one vendor, again no problem. However, we asked this vendor for any schematics, datasheets, and specs.
(continued) The vendor refused to give that information to us. We explained to them that our company doesn't even make COM Express boards at all so competition was literally impossible. They still refused. We then told them that wouldn't mind signing an NDA to get these schematics, specs, etc. THEY STILL REFUSED. My VP blew up in their face and was literally yelling on the conference call about, and in his words, "bulls**t" it was that they refused to let us develop our products with...
(continued again) ... their COM Express module. We wouldn't be able to troubleshoot any SPI, I2C, PCIe, network, etc. signals coming from that COM Express for our product. Today, they've given us some "teasers" from their schematic but it doesn't even help since we don't even have a layout gerber to fully pinpoint where the signal is.
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@NickAlexeev I've only seen a package with solder ball joints on the bottom but not two rows of pads... That's really strange.
Very strange indeed... and to have them connected? Why have the other set at all then? Seems to me, no matter which set you chose to use, the other would be a "keepout" nightmare. I'll avoid such packages. If we all avoid it, maybe it will go away.
I suspect that since they're near the "minimum pitch" of a QFN at 0.5mm pin spacing, they can't just use the inner pins.
The die is only as big as the thermal pad, maybe a decent amount smaller
In the QFN packages I've seen, the leadframe doesn't extend very far into the package. Wirebonds from the outer ring of pads to the chip would be very long, and probably a lot of inductance, which the application may be sensitive to (HDMI)
So this is probably an economical way of extending the leadframe further into a QFN package, and still having support before the plastic is added