Caféflex is complete and open source on GitHub:
LINK
Caféflex usage will eventually be integrated into the trim guide; in the meantime, this post will have some notes for early adopters!
As planned, caféflex relocates the SLC (NAND), has a microSD slot for eMMC replacement, and a WiFi module connector. I searched long and hard for the Wifi B2B connector PN (with help from the Discord homies!) but it seems all the wireless modules on the Wii U use custom connectors. So the connector has to be harvested from a Wii U, which isn't a big deal since users will be trimming off that part of the board anyway. To avoid melting the connector, just blast the underside of the mobo with ~420C hot air until the B2B slides off.
While designing the flex, I did some tests to see which WiFi module GPIOs are actually required. Turns out
none of them are! Some need to be high, and others need to be low, but none actually need to be connected to the SMC/RTC/SOC. Again, this info will eventually be added to the trim guide. For now, here's a schematic snippet:
I ordered some flexes from PCBWay (0.12mm thickness, 0.5oz copper) and assembled them tonight. Always get an electropolished stencil, it makes pasting a breeze.
Removed C194 and wicked off the excess solder. I wicked off TP162 too. Then I scraped and tinned the 0.8mm pitch vias under the SOC. (I scraped more vias than necessary-- you only really need to expose the ones that align with the flex.)
After tinning it was just a matter of aligning everything and soldering away!
I added numerous mechanical solder pads to the design, to hold the flex down. This is critical when there are connectors on the flex! The ones near the SD card and NAND are GND points. But the ones under/around the Wifi connector are actually on the 1V pour, so beware.
The 3.3V wire needs to be very low profile so as not to interfere with the microSD slot. I was lazy and omitted the GND wire, since there are already many GND solder blobs between the flex and mobo. The Wifi module also gets a 3.3v wire to its dedicated solder pad (not pictured).
The Wifi module had to be slimmed down so it wouldn't collide with the NAND and microSD slot.
Plenty of clearance after desoldering the can! Final builds should still have some kapton between the module and flex.
The end result: an ISFSHax-modded Wii U with relocated SLC and WiFi module! Worked first try. I still need to rebuild the MLC and flash it to a high quality, high capacity SD card, so the SD part of the flex remains untested for now.
Very pic heavy post for testing a single flex. Oh well...
EDIT: Rebuilt the MLC onto a 256GB microSD. Everything is working perfectly! Goodbye, eMMC!