SanDisk’s Amazing 512GB SD Card

SanDisk's 512GB SD CardSanDisk has introduced an SD Card with a whopping 512 gigabytes of storage.  Noting that SD Card capacities have increased by 1,000 times over the past ten years, from 512MB to 512GB, the company says that this product is aimed at professional HD videographers (who can justify its $800 price) allowing them to shoot Raw-format footage without shutting their cameras off, which could potentially allow them to miss a magic moment.

To The Memory Guy this represents an amazing piece of packaging technology.  Let’s see why:

In 2003 SanDisk’s 512MB card contained four 1Gb (128MB) NAND chips, the densest chip at that time, plus a small controller.  Although I haven’t yet checked with SanDisk to see how many chips are used in the new 512GB card, today’s highest-density NAND chips are only 128Gb or 16GB.  To get 512GB you would need to use 32 of these chips.  AnandTech estimates that these chips have an area of about 140mm².

SanDisk and its competitors regularly stack NAND chips to achieve higher densities.  The most common configurations stack 2 or 4 chips,  and both SanDisk and Samsung have announced 8-chip and 16-chip stacks.

The SD Card format is 25x35mm  As many as six 140mm² chips could fit alongside each other in this card format if the chips had the exact right dimensions, so it is conceivable that SanDisk uses four of its eight-high chip stacks to squeeze those thirty two 16GB chips into an SD Card’s footprint.  If only two chip stacks are used then each stack would need to use 16 chips.  Either approach would leave plenty of room for the SD Card’s small controller.

When you step back and look at this, though, it is clear that the three orders of magnitude growth from a 512MB SD Card to a 512GB rendition was facilitated by two phenomena: First, the chip density grew by 100 times from 1Gb to 128Gb.  Second, the last order of magnitude was achieved by learning how to squeeze 32 flash chips into a package that, in 2003, was used for only four chips.

Of course, the number of gigabytes of NAND flash shipped during that same period has grown by about 2,000 times, but that’s another story!

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