I have tried via hot air, heated plate to hand soldering with the iron. The hot air will melt the connector so that won't work unless you heat from the bottom the the PCB. Hand soldering is also almost impossible because you can't really get to the pins and if you just slightly touch the plastic it will melt immediately. I also could not get it to work with solder paste and a hot plate. The pins are so small they don't want to adhere to the PCB. I may need to get gold plates pcbs and a stencil to place the exact amount of paste I need to get this to work. A QFN package is easy to solder in comparison.
Is there any particular reason you can't use the featherwing package that adafruit sells? I've seen a few other folks on tindie selling other board and screen combos but personally, for my money, the feather format is pretty good for almost anything I could want to do in this form factor.
https://www.aliexpress.com/wholesale?catId=0&initiative_id=S...
https://www.aliexpress.com/premium/blackberry-q10.html?d=y&o...
https://www.aliexpress.com/item/1005002813523676.html?spm=a2...
Arturo has done alot already:
https://twitter.com/arturo182
The keyboard is analysed:
https://github.com/arturo182/BBQ10KBD
A machine has been designed, but it does not have the goal of fitting inside the cases linked to above - it's on a bare board:
https://www.youtube.com/watch?v=wr3DtQQuUfI
It's available as a product including source code and design files - again, not designed to fit into the cases above.
https://www.tindie.com/products/arturo182/keyboard-featherwi...
Revision 2:
https://www.solder.party/docs/keyboard-featherwing/rev2/
And the Blackberry keyboard standalone:
https://www.solder.party/docs/bbq20kbd/
Design files:
https://github.com/solderparty/keyboard_featherwing_hw
Source code:
https://github.com/solderparty/bbq10kbd_i2c_sw
All that is left is for someone to do the same, with the aim of fitting into the cases listed above.