Dual SIM + micro-SD Hack

Dual SIM smartphones are now common.

But most of them due to the card tray design, can either accept:

  • two SIM but no micro-SD
  • one SIM and a micro-SD card

This is definitely a bugger since mid-range Android smartphones are pretty stingy with storage memory (from 16Gb to 32Gb), while micro SD are pretty cheap an wayyyyy larger (128Gb to 512Gb)

Here is the quick hack to insert both dual sim, and a micro SD.

Tools needed

Peel the back of the nano-SIM plastic, with a hot air gun, as it’s soften the back glue, heat gently and evenly the back, to not fry the sim. (you may want to try first with a discarded SIM card, sitting in your junk-box)

Peeling the plastic card of the PCB/Chip

Clip about 1mm the sides of the FR4 epoxy SIM card

Clipping the SIM PCB with scissors

File the edge on the micro SD card, so it’s thinner, and don’t have this edge protruding anymore and shaves few microns of the card.

It’s interesting the flipchip design, reflown or wire bonded on a thin PCB with the finger contacts, then overmolded with the final plastic case. 400Gb are store in this die, that’s awesome, I guess, the controller must be integrated too, not separated as in Bunnie’s entry: https://www.bunniestudios.com/blog/?page_id=1022

I don’t know if one can reflow this design as experimented here: http://www.dotmana.com/weblog/2015/08/microsd-card-reflow-quick-and-dirty-pcb-with-kicad/

Tape one side of the smartphone card tray, with the first sim card and the micro-SD

Front of the card tray (yes, the first nano SIM was already homemade, from regular SIM, to micro, then nano, went under the knife quite few times)

Tape the other side with the shrinked second SIM

(take extra care where the chip should align, here I made scratches with the scalpel with the unmodified nano sim where it should go)

Here I used Kapton tape, but I guess any office tape would do

Back of the smartphone card tray, with tape holding the secondary SIM

That’s it! Dual sim and lot of storage! 400Gb, gosh!

SYMA is my secondary wireless provider, and F SFR my first

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