While we don't usually cover SD cards, SanDisk's announcement of 512GB Extreme PRO SD card caught my eye today. There are currently only a couple of 256GB SD cards available and most OEMs have not been able to go above 128GB, so the Extreme PRO is the highest capacity SD card in the world, which really speaks for SanDisk's NAND and packaging expertise. 

SanDisk Extreme PRO SDXC UHS-I Memory Card Specifications
Capacities 128GB, 256GB & 512GB
Read Speed Up to 95MB/s
Write Speed Up to 90MB/s
Warranty Lifetime Limited

The Extreme PRO comes in SDXC format and utilizes UHS-I interface, which is good for up to 104MB/s. As you can see in the table above, the Extreme PRO comes very close to saturating the interface and it carries UHS Speed Class 3 rating, meaning that it is suitable for capturing 4K video. The largest market for the new Extreme PRO SD cards is obviously video professionals because as we transition to 4K video, the need for storage increases substantially, which in turn opens market for larger SD cards.

While SanDisk didn't release any details of the internals, it's pretty safe to assume that the 512GB Extreme PRO consists of 32 x 128Gbit (16GB) dies. The photo above is from SanDisk's 2014 Investor Day presentation where the company claimed that it has the technology for a 32-die SDXC card and with the Extreme PRO the technology has made it into the retail. Since SanDisk/Toshiba doesn't have a 256Gbit NAND die (nobody has one in mass production yet), the only way to achieve 512GB is through a 32-die stack. SanDisk hasn't specified whether the NAND is MLC or TLC, but given that it is a high-end product I'm guessing it is MLC based. 

EDIT: As some of you mentioned in the comments, it seems to be two 16-die stacks instead of a single 32-die stack. SD cards definitely have the room for two die stacks and the photo also shows two 16-die stacks instead of a single 32-die stack. Either way it is impressive since nothing else comes close to the capacity SanDisk offers.

All capacities are available now and the MSRP for the 512GB model is $800, which is certainly high since 512GB SSDs retail for close to $200. However, the Extreme PRO is the only SD card that is available in such a high capacity, so I would say the premium is justified. Stacking more dies on top of each other will always have a negative impact on yield as the wires have to be longer and there are more wires to connect, so the room for errors increases and thus the manufacturing cost goes up as well. 

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  • Guspaz - Thursday, September 11, 2014 - link

    The people who care about really high bitrate 4K video (when you're recording to ProRes or DNG something RAW-like) aren't recording to SD cards anyhow, they're recording to SSDs directly.
  • Barilla - Thursday, September 11, 2014 - link

    About 75% of people I know sill use hard drives this size or smaller.
    Talk about insane...
  • jjj - Thursday, September 11, 2014 - link

    You don't say it straight up but the article suggests they stacked 32 dies and i don't think that's it since it's not needed.. Even the pic has 2 sets of dies. W/e you intended to say,maybe better to make it clearer.
    In their 128GB microSD they do stack 16 dies and the controller inside a 1mm thick package so in pure theory they should be able to do 32 dies in 2mm.
    But a SD card is 32 x 24 x 2.1 mm so there should be room for 2-3 stacks (32x24 is 768mm2) even if they use the second gen 19nm not the 15nm MLC. Your guess was 139mm2 for 15nm MLC and i assume second gen 19nm is well bellow 200mm2 while first gen 19nm at or slightly above 200mm2.
    Guess they could even use 64GB dies ,there is plenty of room if they would go with 4 stacks of 16 dies and might make more sense than to go with 2x16 bigger dies, yield wise.
  • jjj - Thursday, September 11, 2014 - link

    64Gb dies not GB obviously*
  • extide - Thursday, September 11, 2014 - link

    There is only enough room for one stack in an SD card, MAYBE 2. Definitely not four though. The z height isn't going to be a concern though, because I doubt the 32 die stack ends up being much taller than a 16 die stack by the time it's packaged up and whatnot.
  • jjj - Thursday, September 11, 2014 - link

    lol i hope and assume you are just trolling on purpose but for the sake of others i'll reply.
    You have the SD card dimensions in my first post and die sizes so yes you can fit a bunch of stacks next to each other(assuming everybody around here passed second grade math). In fact even old school cards had a couple of NAND packages and a controller on a PCB..There is lots of space in a SD.
    Fitting 16 dies in 1mm or 32 in 2 mm is something everybody else is yet to do, it's a remarkable thing that Sandisk managed to achieve and 16 or 32 not at all the same thing.
  • hojnikb - Sunday, September 14, 2014 - link

    Actually, samsung has been doing 16 die stack for quite some time now. So its not a sandisk thing.
  • DanNeely - Saturday, September 13, 2014 - link

    You most definitely can fit 4 stacks into an SD card; uSD cards have one and full size SD cards are more than 4x larger (32x24mm vs 15x11mm). You might even be able to squeeze 6 stacks in; depending on how much of the uSDs area is taken by external packing and the USB-Flash controller chip.
  • hojnikb - Sunday, September 14, 2014 - link

    Yeah, but you can only fit one half sized die (eg 64Gbit at 19nm). So one package and 16 dies is all you can get away with on mSD cards.
  • MadMan007 - Thursday, September 11, 2014 - link

    So UHS has been out for a while. What devices actually use it? Just cameras? Also, are there commodity-priced UHS card readers?

    UHS sounded so cool when I read about it, but then I realized it means nothing without device support. Chicken and egg, I know, but this is one damn slow cooking chicken.

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