In the recent years SSDs in M.2 form-factor have greatly reduced the amount of space required for storage sub-systems inside modern PCs. However, as computers get even smaller, there is pressure for SSDs to further shrink as well. Solid-state drives in BGA packaging are considerably smaller than SSDs in M.2 form-factor and for a couple of years platform developers like Intel have been promoting such drives among PC makers. Intel said in 2014 that an M.2-2260 SSD could take 15% of space inside a 2-in-1 hybrid PC, whereas usage of a BGA SSD could save a great amount of space and could allow to increase battery size by around 10%. Moreover, in many cases usage of BGA storage can shrink Z-height of devices as well as improve thermal performance compared to M.2 modules, according to Intel.

As a result, the market for BGA form factor SSDs has been growing in size and importance at a quick pace. To that end, at the 2016 Samsung SSD Forum Japan, Samsung demonstrated its first SSD in a BGA (ball-grid array) packaging. Despite of tiny form-factor, Samsung’s PM971 SSD offers rather high performance thanks to PCIe interface and a special controller. Meanwhile the little drive will be targetted for use inside PCs, tablets, 2-in-1s and other types of small computers or embedded applications.

First BGA SSD From Samsung

Samsung’s PM971 SSD is based on Samsung’s new Photon controller as well as MLC V-NAND flash memory. It is impossible to say at this time whether the Photon controller of the PM971 SSD has anything to do with the controller used inside the 750 EVO drives (the controller is smaller than usual as it has only two processing cores), but it looks very likely.

Samsung plans to offer three versions of the SSD, featuring 128 GB, 256 GB, and 512 GB capacities. The PM971 SSD supports sequential read speed of up to 1500 MB/s as well as sequential write speed of up to 600 MB/s, suggesting that it relies on PCIe 3.0 interface. The PM971 SSD can perform 190K random read IOPS as well as up to 150K random write IOPS, according to information disclosed by Samsung.

Samsung PM971 SSD. Image by PC Watch.

At the event, Samsung did not reveal anything about internal architecture of its BGA SSD, which is rather interesting because the NAND controller has to extract maximum performance out of a limited number of NAND devices over a limited number of channels (provided, of course, that internal architecture relies on industry standards). Moreover, it is unknown whether the drive is compatible with the proposed M.2 specification for BGA SSDs. The only thing that is known about the SSD right now is that it is smaller than an SD card, according to PC Watch web-site.

Samsung is aiming for tablets and 2-in-1 hybrid PCs with its BGA SSDs, The company expects device manufacturers to adopt the product in the second half of 2016 or in the first half of 2017.

Standards for BGA SSDs Proposed

While we're on the subject of BGA SSDs, this is a good time to touch upon the recent developments in the standardization of SSDs in this format. Even with the recent growth of the market, SSDs in BGA packaging are not something completely new. Intel, Toshiba, SanDisk, Microsemi, Silicon Motion and some others have all offered SSDs in BGA form-factors for years to various makers of embedded applications, whom in turn needed to save space or run their storage sub-systems in harsh environments. Early last year Toshiba rolled-out its first BGA SSDs with PCIe interface, and in September several members of PCI SIG (the organization, which develops PCIe interface, its derivatives and standards for PCIe-based devices) proposed a set of mechanical standards for BGA SSDs, which could open the doors for many manufacturers to enter the emerging market.

BGA SSDs with PCIe 3.0 or SATA interfaces will be a part of the PCI SIG’s M.2 specifications. At present select members of the organization (HP, Intel, Lenovo, Micron, SanDisk, Seagate and Toshiba) propose four types of soldered-down solid-state storage solutions: Type 1620, Type 2024, Type 2228 and Type 2828. M.2 types traditionally define width and length of the package in millimeters, so, the smallest BGA SSD will have measurements of 16 × 20 mm, whereas the largest BGA SSD will feature 28 × 28 mm packaging. SSDs in a BGA package may have Z-height up to 2 mm (measured with solder balls collapsed), but may be slimmer.

BGA SSDs that comply with the proposed M.2 types use the same signals as the M.2 socket 3 (so, they are compliant with both PCIe 3.0 and SATA 3.2 protocols and can utilize up to four PCIe lanes), but use 1.2V, 1.8V and 3.3V power rails. All the BGA SSDs contain the common core ball map of Type 1620 (which look pretty much the same as the core ball map of Toshiba’s BG-series SSDs) for data and power, but the larger drives also feature additional mechanical retention balls. Some BGA SSDs can be placed on M.2 modules in a bid to enable design flexibility for device makers (and upgradeability option for end-users), but only on the condition that the modules have voltage conversion circuitry to provide 1.8V or 1.2V as required.

A BGA SSD not only integrates NAND flash memory, but also a NAND controller, DRAM and all the things that could be needed for a fully-functional solid-state storage solution. From the software perspective, M.2 spec BGA SSDs are just solid-state drives with PCIe or SATA interfaces. And unlike MCPs (multi-chip packages) consisting of DRAM and NAND that companies like Micron and Samsung offer to makers of mobile devices, BGA SSDs are complete storage systems that can be attached directly to appropriate host interfaces.

The proposed BGA M.2 form-factors intend to unify packaging of single-chip SSDs and make such SSDs industry-standard devices available from various makers. It is unknown at this time whether Samsung’s PM971 will be compliant with the proposed specs, but it's worth noting that the company is a member of PCI SIG and typically makes products in standard packages and form factors.

Source: PC Watch

Comments Locked


View All Comments

  • Ryan Smith - Tuesday, March 22, 2016 - link

  • Vorl - Tuesday, March 22, 2016 - link

    just a heads up, you have a typo. 4th paragraph: can perform 190K random write IOPS as well as up to 150K random write IOPS

    The first one should be read.
  • plopke - Tuesday, March 22, 2016 - link

    I can barely understand anything of all this M.2 stuff . Trying , but I need to look at AHCI/NVMe , PCIe2/4/sata and all that is just branded M.2. So how would BGA effect me as a regular consumer?

    Urgh I wish they would take more of a USB/sata approach , which isn't perfect but something like M.2(AHCI/sata) M.3(NVMe/PCIe2), M.4(NVMe,PCIe4). Just something so the devices says compatible with M.2,M.3 and M.4 , because so many times if I wanne buy something on a website the specification is wrong/missing or it contains a Asteriks on their site stating depends on your region.
  • bcronce - Tuesday, March 22, 2016 - link

    AHCI supports one queue with a depth of 32 requests. This is hardly enough to keep a modern SSD busy. NVMe, which M.2 implements, supports 65,535 queues each with a depth of 65,535 requests.

    There is no point in making these devices backwards compatible with AHCI/SATA. The whole issues is AHCI/SATA was too slow. It's like saying we need to make jet engines compatible with prop airplane design. In order to go faster, we need to break the mold.
  • DanNeely - Tuesday, March 22, 2016 - link

    M.2 has a dozen possible keyings (A-M) and 11 possible slotted form factors (see diagram in article), and 8 possible thicknesses (urgh); it's intended primarily as an OEM interface not a consumer one and has way too many moving parts to get everything marked out like that even if was just an SSD spec. As a simplifying factor a lot of that seems to be spelling out every possible option now instead of trying to squeeze them in after the fact.

    Only 5 of the keyings are defined and 3 actually used for current mainstreamish products (A - wifi, B - Sata/2x PCIe/sata SSDs, and M - 4x PCIe/sata SSDs). The SSD situation is settled a bit more by most systems using B/M slots. Long term x4 PCIe means that M's going to replace B for SSDs. PCIe is forward/backward compatible; you potentially leave performance on the table but if they fit they should work.

    Sizes are defined by dimensions in mm and again only use a fraction of the available options. The 30mm wide ones are no-shows (I assume this was a sop to previous larger mobile card spec vendors so they could pretend not to need to change up as much all at once), and I've not seen anything using the ultra narrow 16mm form factor yet. Everything uses the 22mm wide versions: Wifi the smallest 22x30 size, SSDs can use the 22x42/60/80/110 sizes but AFAIK most are either 2242 or 2280 with 2/4 flash chips on them. 22110 would allow for 8 flash chip modules like in 2.5" form factor drives; but even desktop mobos tend not to free up enough space to fit one. At this point I suspect it's dead in the water; and hope U.2 (a 4xPCIe cable) will actually ship allowing for high performance 2.5" SSDs. PCIe m.2 ones currently have most of the speed titles due to larger bandwidth; but the smaller number of flash chips limits their capacity and in some cases bottlenecks them.
  • stephenbrooks - Tuesday, March 22, 2016 - link

    Great info! I'd happily read an article about this sort of thing, since these sort-of-internal interfaces in smaller devices aren't always obvious (nor is what is compatible with what).

    I also wish they'd find a ZIF type socket that gives the smallness of BGA without being actually soldered down but I guess that's impossible or someone would have figured it out by now...
  • DanNeely - Tuesday, March 22, 2016 - link

    Probably not going to happen. You can space balls more tightly than holes in a socket. Intel's LGA socket probably comes closest in connection density; but the locking lever needed to hold the chip down tightly enough for good contact is hardly zero force.
  • plopke - Tuesday, March 22, 2016 - link

    @DanNeely , thx for the short summary ! Hope i can remmember it all if i ever upgrade a laptop or something and hope U.2 gets standard on my desktops :)
  • frenchy_2001 - Tuesday, March 22, 2016 - link

    To be precise, M.2 and U.2 are physical connector and board space specifications.
    M.2 is the specification for mostly mobile, U.2 is a superset of a SAS port.

    Another very similar spec is USB type C. Similarly, it defines the physical connector, but *many* different signals and/or power can transit on it, depending on the specifications supported. Signals for USB 3.1, Thunderbolt, DisplayPort can be carried and the port can use USB power specs, allowing up to 100W (20V x 5A).

    Similarly, M.2 can carry PCIe signals (2x lanes or 4x lanes), SATA and more.
    For the desktop, the latest spec is U.2, which is a superset of SAS and can carry SATA, SAS and PCIe gen3 x4 lanes.

    Basically, we are moving more and more towards universal plugs and cables, with the controller defining what transits on top.
  • bill.rookard - Tuesday, March 22, 2016 - link

    Hmmmm... I see this, with 512GB and a SSD controller in a single 28mm x 28mm chip, and I'm wondering to myself... where are the AFFORDABLE 4TB SSDs? It would take 8 of these chips minus the SSD controllers of course plus one other controller. Or an 8TB which would be 8 chips on each side of the PCB.

    Competition will help pricing once the other fabs get their VNand equivalents out...

Log in

Don't have an account? Sign up now