Product showcase

And here's the PCB (printed cicuit board) with all SMT soldered ICs. This 6 Gbps storage unit makes use of Toshiba 20nm MLC written NAND flash ICs. There are a number of peculiar things going on with that PCB, let me talk you through that.
 

Above you can see the PCB, the big chip to the left is the controller (Marvell 88SS9187). The IC can hardly be read due to sticky thermal cushions leaving some residue making photography rather hard.

Located to the right from the controller we spot 20nm NAND flash ICs from Toshiba dubbed under SKU/product code TH58TEG8DDKTA20. 

The Plextor M6S SSDs each get a DRAM cache. To the top right you can see two Micron 512 MB DDR3-1600 DRAM packages, giving this product a whopping 1 GB data cache.

• 128 GB  gets 256 MB
• 256 GB  gets 512 MB
• 512 GB  gets 768 MB

 These caches are DDR3 based and as you can see, made by Hynix.

Typically on the backside of the PCB you'll see SMT traces for more NAND chips, this is not the case for these Plextor M6S. So I would not expect larger volume sizes anytime soon for this model. 512GB is the largest model you can purchase.