20 ms·

Goodbye, Motherboard. Hello, Silicon-Interconnect Fabric

345 points by craigjb 7y ago

mooman219 7y ago
Another drawback the article doesn't mention is tight component coupling removes the ability to treat the components as separate pieces. This can make repair or upgrades extremely difficult. This might be desirable for companies against the right to repair; if it's illegal to use software to prevent repair, making it sufficiently difficult by hardware design is a possibility.
- deleted 7y ago
  [deleted]
- sneakernets 7y ago
  This sounds like making the entire motherboard an equivalent of an epoxy blob.
- repair_man 7y ago
  Is anybody actually repairing a faulty motherboard? Let's one of the chips or some resistor is broken.
  - deleted 7y ago
    [deleted]
  - zeta0134 7y ago
    Yes, quite often in fact. On older motherboards, often the only problem is something benign like a blown capacitor, which is a few cents at the hardware store and a few minutes labor to desolder the old and attach the new. It's a really common part to wear out due to heat stress, and it manifests as funky logic problems, since the caps are mostly there to clean up the line noise. I've saved a few flatscreen monitors this way, that were flickering and unusable; I'll take a $5 handful of parts over a new $179 monitor any day of the week.
    - littlestymaar 7y ago
      I have a friend who buy disfunctionning TVs for a few euros, and most of the time (8-9 over 10) there is only one broken capacitor that need replacement. He makes maybe one hundred euros every month by doing so, with really little work.
    - ryanwaggoner 7y ago
      I have only a rudimentary understanding of electronics and what the various components do, so this may be a dumb question, but how on earth do you diagnose an issue like this? If my monitor dies or my printer stops working and I open it up, I’m completely bewildered at what steps you’d take to figure out that some random resistor or capacitor out of (what seems like) thousands of components is the one causing the issue. Do you just go through and test each one with a multimeter until you find it?
      - jabl 7y ago
        Faulty capacitors often bulge, so you can find them by visual inspection.
        userbinator 7y ago
        Bulge, or even just burst open and start leaking: https://en.wikipedia.org/wiki/File:Al-Elko-bad-caps-Wiki-07-02-17.jpg https://en.wikipedia.org/wiki/File:Al-Elko-bad-caps-Wiki-07-...
      - zeta0134 7y ago
        That's the general idea, yeah. I always start with the power supply because that part is under the most electrical strain, and tends to get hot. That means its components are often both the first to fail, and the most likely to cause weird problems when they do fail. Other than that, it's just intuition about how I think the device probably works, and a lot of trial and error. Major bonus points if there's a datasheet available, or a kind forum poster has had a similar problem to give me a lead on where to look.
      - bradstewart 7y ago
  - ryukafalz 7y ago
    You should check out Louis Rossmann's videos on YouTube - he does exactly this. This one's not on his channel but is a good example: https://www.youtube.com/watch?v=g0S1ku9xvDI https://www.youtube.com/watch?v=g0S1ku9xvDI
  - jdnenej 7y ago
    I have seen videos of people buying in batches of broken game consoles and replacing USB connectors and charge controllers since they often break and are not too hard to replace with the right tools. I also spoke to someone from Russia who worked as a electronics repair person fixing things we would normally throw away because the price of new equipment is very high compared to the price of an expert's time to fix it.
- lettergram 7y ago
  That might be fine if they can produce them cheap enough... I’m sure the same arguments were said when the CPU switched to having non-repairable transistors
- richdougherty 7y ago
  There is this section, which acknowledges the problem of replacing components: "We also need to consider system reliability. If a dielet is found to be faulty after bonding or fails during operation, it will be very difficult to replace." Their proposed solution (which is not repair): "Therefore, SoIFs, especially large ones, need to have fault tolerance built in. Fault tolerance could be implemented at the network level or at the dielet level. At the network level, interdielet routing will need to be able to bypass faulty dielets. At the dielet level, we can consider physical redundancy tricks like using multiple copper pillars for each I/O port." Your point is still valid, just wanted to call out their their thoughts on the issue.
  - nine_k 7y ago
    Big CPUs / GPUs already have physical redundancy, and a way to cut / rewire a limited amount of faulty parts by laser etching in the die, prior to packaging.
    - monocasa 7y ago
      Cell processors are interesting because they do quite a bit of binning on a user facing SPI slave. You shift a thousand or so bit payload into it from a support/binrg up processor that tells it which pieces are disabled, how the PLLs are configured, etc. Hacked PS3s could reenable the binned off 8th SPE for instance.
  - jdnenej 7y ago
    That doesn't seem to solve the issue of when a chip fails all together. While difficult, it's not impossible or unheard of for people to replace chips on a PCB like a charge controller that has fried.
  - BAReF00t 7y ago
    It’s not just about faults. But about customizability and upgrades! I like to choose how much RAM and storage and which ports I want with how many generic, vector, FPGA and neural cores, thank you very much. And I like to change them later, to upgrade gradually. Even buses.
tartavull 7y ago
You can order custom pcb from China for a couple of dollars. How likely is that this technology will be affordable at small quantities?
- jabl 7y ago
  Seems one of the main advantages is higher density of conductors and connectors compared to a PCB. Aligning those dielets with micrometer precision would seem to require equipment out of reach for the hobbyist. And then bonding them, while they don't use solder but rather temperature and pressure, again with such small connectors I guess the line between bonding and destroying the thing is very very fine. Again requiring specialized and presumably expensive equipment.
- Insanity 7y ago
  First of all, I'm no expert (at all, I stay firmly on the software side of things) but here's my 2c: I'm going to guess that when PCBs were introduced, you couldn't get them for a couple of dollars from China either. These kind of things tend to become cheaper over time, as manufacturing, competition (newer or competing components) and availability grows. So I assume it's at least possible that at some point, a few decades from now, they're cheap :)
korethr 7y ago
I kinda like this idea, but I think it only makes sense where the end product sold to the intended consumer is wholly integrated. So, this might make sense for a smartphone. Or perhaps custom systems in Google- or Amazon- scale datacenters, with a number of different custom types tuned to exactly the work each is intended to do, and packed as densely as the intersection between thermodynamics and economics will allow. But, I don't think we can escape the need for packages and PCBs entirely. At some point, you're going to need to interface with something that either A) you don't or can't control, or B) something at appropriate scale for interfacing with the humans whom the fancy system is ultimately supposed to serve. In either case, here come standard connections that are much bigger than the chiplet dies or the interconnect fabric between them, and thus, the need for PCBs to connect the Systems-on-a-wafer to the outside world. As such, I think it will be a while before I can pick components out on Mouser's website, and have all those component chiplets fused to an interconnect wafer and delivered to my home or employer's shipping dock (though that would be damned awesome).
- gumby 7y ago
  > As such, I think it will be a while before I can pick components out on Mouser's website, and have all those component chiplets fused to an interconnect wafer and delivered to my home or employer's shipping dock (though that would be damned awesome). I agree. People have been talking about that future since at least the 1990s (back then SOC didn't mean a somewhat standard chip with a lot of peripherals, but literally a custom die with your own hardware on it). "Hardware/software co-design" was part of the jargon of the day. I'm not holding my breath. But I do imagine seeing a lot of consumer products go this way. Not a $3 IoT light switch/malware vector, but anything that gets rid of connectors is a win on both the BOM and reliability standpoint, but anything in the $50-$500 price range with volume over a million units is probably worth it.
jpm_sd 7y ago
"Power turned out to be a major constraint. At a chip’s standard 1-volt supply, the wafer’s narrow wiring would consume a full 2 kilowatts. Instead, we chose to up the supply voltage to 12 V, reducing the amount of current needed and therefore the power consumed. That solution required spreading voltage regulators and signal-conditioning capacitors all around the wafer, taking up space that might have gone to more GPU modules." Uh, this seems like a pretty serious downside.
- deleted 7y ago
  [deleted]
- jjoonathan 7y ago
  Also: shifting PCB prototype costs in the direction of silicon is going to be a tough sell for many applications. > Another drawback of SoCs is their high one-time design and manufacturing costs, such as the US $2 million or more for the photolithography masks > ... 6 paragraphs later ... > Patterning wafer-scale Si-IF may require innovations in “maskless” lithography.
- willis936 7y ago
  Resistive losses are that high? The signal integrity issues are going to cause unacceptably high error rates.
- baybal2 7y ago
  Silicon's limit is 0.7V and there is no trick against that. No matter how efficient is your power supply, you will be losing electricity very very rapidly within single centimetres. That's why there is no way to work around the need to move the voltage conversion on chip. In the future we may even increase IC voltage to reduce the copper losses for very low power, but huge devices.
holy_city 7y ago
I like the idea of faster and smaller devices but dislike the idea of expensive production methods that are only realizable with heavy capital investment and large volumes of products. Like I can realize a PCB prototype in my apartment (or rather, my parking lot without telling my landlord), or rent a CNC machine at a makerspace/public library to do it. If I need the thing fabbed with a nice solder mask and silk screen, I can have it made for < $20 domestically with under two weeks lead time. Component sourcing is even easier. But where do I go to have the chiplets I need for the circuit? Organize the logistics to ship them to the clean-room where they can be packaged on this fabric? How many widgets do I need to ship for this to be viable, or for the contract fab to not laugh at me? How do I prototype? How long is the lead time? It just seems like there's a lot in the way of this being viable for run of the mill projects.
- jabl 7y ago
  Increasing capital costs and consequent dependence on huge volumes have been a defining feature of the semiconductor industry since the invention of the integrated circuit. AFAICT this technology will have no impact on the low end hobbyist end of the market, but rather (if all works out) enables those $zillion behemoths to produce ever faster systems since they won't be as bottlenecked by off-chip bandwidth as they are with today's PCB's.
- BAReF00t 7y ago
  You’ll need $2 million, just for the mask. And if you want to fab yourself, the machines cost in the range from $10 to $50 million. For one machine. And you will need many. As the article states, you will not make those at home any time soon, unless ”maskless“ fabbing becomes a thing.
cphoover 7y ago
Will this increase the number of bit flips from cosmic rays?
- brootstrap 7y ago
  All the cool kids these days are _wearing_ nodeJS , not just writing it!
craigjb 7y ago
It's been fun to see Dr. Subu present this concept and prototypes at several conferences, and the level of integration possible is absolutely insane. I think the industry is definitely moving toward chiplets, such as the latest AMD release. I definitely think we will see more chiplets and more standardization on interfaces between chiplets. The focus will be on how to minimize energy per bit transferred (a big topic in Subu's talks) and how to minimize the die area used for inter-chiplet communication. In monolithic silicon, you don't have to think about die area, since your parallel wires between sections might just need a register or two along the way. With chiplets, you typically can't run wires at that density yet, so you still have some serialization/deserialization hardware. But, since it's not crossing multiple high inductance solder balls and PCB traces, you can get away with less. Hopefully also you can get away without area-intensive resynchronization, PLLS, etc. I think it will definitely be awhile before this kind of integration is used outside of niche cases though. The costs are just insane. You have to pre-test all manufactured chiplets before integration, and that test engineering is nothing to sneeze at. If you don't then you have all kinds of commercials issues about who is liable for the $500k prototype one bad chip broke. On the bright side, I see the chiplet approach benefitting other integration technologies. For example, wafer level and panel level embedded packaging technologies can be used for 1-2um interconnects now. You won't get a wafer sized system out of it with any kind of yield, but it's probably the direction mobile chips and wearables will go. Anyway, disorganized info-dump over.
- jabl 7y ago
  I agree this looks promising, though I'm not an expert in this field. But the title is a bit, well, overpromising or broad. I don't think we'll replace traditional motherboards anytime soon (except maybe in smartphones?). Rather, it will be an incremental progress. - first, SoC's will be replaced with chiplets - then we'll start seeing more and more stuff being integrated on this wafer. - say, instead of a server motherboard with multiple sockets, have all the CPU chiplets on the same wafer and enjoy much better bandwidth than you get with a PCB - integrate DRAM on the wafer. This will be painful as we're used to being able to simply add DIMM's, but the upside is massively higher bandwidth. The motherboard pcb per se will live for a long time still, if nothing else then as the place to mount all the external connectors (network, display, pcie, usb, power, whatnot).
cududa 7y ago
Color me skeptical, but I remember being 12 seeing this on The Screen Savers on TechTV in 2003
ChuckMcM 7y ago
This step is inevitable in my opinion. This is especially true for mixed signal (that is some digital and some analog components) systems. It's early fore-bearer (multi-chip modules or MCM) was instrumental in IBM getting its later mainframes to hit the density and thermal constraints. Like the authors, when I saw AMD's chiplet pictures for the Zen2 chips I felt that we would see this expanded. Intel has also done some interesting optical chip to chip interconnects that would facilitate assembling these newer multichip modules into chassis that route signals to and from the outside world. The next (and perhaps last) element to fall into place is a way to efficiently cool these systems. One of the problems that large data centers face is not that they want "smaller" boxes but that they need to pull enough heat out of a rack of servers in order for them to reliably function.
- jabl 7y ago
  For data centers, while air cooling might be running out of steam, there's plenty of leeway in water cooling. So I don't think that's an insurmountable problem.
  - ChuckMcM 7y ago
    Having been inside Google's data centers I agree with you :-). I did a top level, high efficiency data center design for a multi-tenant hosting with Google scale economics as an exercise once, talked with some potential partners who were very enthusiastic. It would cost roughly double what the existing warehouse type data centers cost to build, but it would repay its costs faster than they did (given colocation cost structures at the time). It also leveraged some of the open compute designs to achieve better density.
Causality1 7y ago
>pack dozens of servers’ worth of computing capability onto a dinner-plate-size wafer of silicon. Congratulations on the insurance money from your building burning to the ground.
seltzered_ 7y ago
“Silicon-interconnect fabric, or Si-IF, offers an added bonus. It’s an excellent path toward the dissolution of the f(relatively) big, complicated, and difficult-to-manufacture systems-on-chips that currently run everything from smartphones to supercomputers. In place of SoCs, system designers could use a conglomeration of smaller, simpler-to-design, and easier-to-manufacture chiplets tightly interconnected on an Si-IF.” Reading this reminded me of a remark from Bunnie Huang’s teardown of a dirt cheap ‘gongkai’ cellphone (https://www.bunniestudios.com/blog/?p=4297 https://www.bunniestudios.com/blog/?p=4297): “To our surprise, this $3 chip didn’t contain a single IC, but rather, it’s a set of at least 4 chips, possibly 5, integrated into a single multi-chip module (MCM) containing hundreds of wire bonds. I remember back when the Pentium Pro’s dual-die package came out. That sparked arguments over yielded costs of MCMs versus using a single bigger die [...] I also remember at the time, Krste Asanović, then a professor at the MIT AI Lab now at Berkeley, told me that the future wouldn’t be system on a chip, but rather “system mostly on a chip”. The root of his claim is that the economics of adding in mask layers to merge DRAM, FLASH, Analog, RF, and Digital into a single process wasn’t favorable, and instead it would be cheaper and easier to bond multiple die together into a single package. It’s a race between the yield and cost impact (both per-unit and NRE) of adding more process steps in the semiconductor fab, vs. the yield impact (and relative reworkability and lower NRE cost) of assembling modules. Single-chip SoCs was the zeitgeist at the time (and still kind of is), so it’s interesting to see a significant datapoint validating Krste’s insight.” I wonder if there’s any advantages to si-if from an ewaste (aka reverse logistics, cradle-to-cradle) perspective
localhost 7y ago
Does anyone know how this compares with AMD's Infinity Fabric? How is it similar or different from it?
- osamagirl69 7y ago
  Infinity fabric is a software thing (a way to distribute information over a buss similar to pci-e) where as this is a physical piece of hardware that electrically passes the signals between 2 chips. I see no reason why infinity fabric could not be routed through a silicon interconnect, but it would be wasteful. The whole point of silicon interconnects that the hardware protocols like pci-e are no longer necessary and can use much lower power/cheaper ways to transfer data.
mhb_eng 7y ago
For reference, there are companies that have developed this to a commercially viable level. First that comes to mind is ZGlue, a company that has the design tools, interconnect fabric, and chiplet ecosystem required to deliver these kinds of devices. https://www.zglue.com/ https://www.zglue.com/
- jpm_sd 7y ago
  This is really impressive work.
bArray 7y ago
Yeah... I'm not entirely convinced about this future. * PCBs are cheaper to manufacturer than silicon wafers. * PCBs can be arbitrarily created and adjusted with little overhead cost (time and money). * PCBs can be re-worked if a small hardware fault(s) is found. * PCBs can carry large amount of power. * PCBs can help absorb heat away from some components. * PCBs have a small amount of flexibility, allowing them to absorb shock much easier. * PCBs can be cut in such a way as to allow for mounting holes or be in relatively arbitrary shapes. * PCBs can be designed to protect some components from static damage. What I can see on the other hand is some packages end up being dropped into the PCB and soldered at the sides. Sometimes this is done with large through-hole capacitors, where the legs are bent and the capacitor sits in the middle of the PCB (inside a cut hole). Other than ball packages, you could could probably drop the majority into the PCB itself. The other obvious option for manufacturers will be to put more tech on a single die, but then other problems are also raised. For example, some parts are binned based on their tested results.
- userbinator 7y ago
  What I can see on the other hand is some packages end up being dropped into the PCB and soldered at the sides. That's been done for at least 30 years: https://www.keesvandersanden.nl/calculators/hp32sii_repair.php https://www.keesvandersanden.nl/calculators/hp32sii_repair.p...
  - bArray 7y ago
    That's amazing and I'm glad that it's possible, even by the standards of older technology. I certainly think dropping packages into the PCB is the lowest hanging fruit for reducing depth.
- willis936 7y ago
  I’d like to add onto your list: * PCBs can act as integrated antennas. * PCBs can easily mount connectors.
Yaa101 7y ago
The downside is that independent entities are not anymore able to design hardware projects, there are only a few companies that can design and make such integrated circuits. Cpu's are not only made for computers but for all sorts of appliances. Time will tell if these big companies will sell chiplets and the tech to assemble them onto silicon to 3rd paties. PCB tech is fairly democratic in that sense.
- jabl 7y ago
  I think it's more fruitful to (initially at least) see this as an alternative to single chip SoC's rather than an alternative to PCB's.
a0zU 7y ago
It seems like promising technology but the cost of making these chiplets must outweigh their benefits.
ColanR 7y ago
It sounds like hardware side of computer science is rediscovering the UNIX philosophy - each unit does one thing, well, with standardized interfaces.
NetOpWibby 7y ago
Cyberpunk 2077, here we come!
BAReF00t 7y ago
Gloodbye customizability and modularity, from a user standpoint. I guess Apple will hire them pretty soon.
wand3r 7y ago
I think it should be called Silicon Fabricated Interconnect so we can just call it Si-Fi...
josebogado 7y ago
oi

345 points by craigjb 7y ago

Another drawback the article doesn't mention is tight component coupling removes the ability to treat the components as separate pieces. This can make repair or upgrades extremely difficult. This might be desirable for companies against the right to repair; if it's illegal to use software to prevent repair, making it sufficiently difficult by hardware design is a possibility.

deleted 7y ago
[deleted]
sneakernets 7y ago
This sounds like making the entire motherboard an equivalent of an epoxy blob.
repair_man 7y ago
Is anybody actually repairing a faulty motherboard? Let's one of the chips or some resistor is broken.
- deleted 7y ago
  [deleted]
- zeta0134 7y ago
  Yes, quite often in fact. On older motherboards, often the only problem is something benign like a blown capacitor, which is a few cents at the hardware store and a few minutes labor to desolder the old and attach the new. It's a really common part to wear out due to heat stress, and it manifests as funky logic problems, since the caps are mostly there to clean up the line noise. I've saved a few flatscreen monitors this way, that were flickering and unusable; I'll take a $5 handful of parts over a new $179 monitor any day of the week.
  - littlestymaar 7y ago
    I have a friend who buy disfunctionning TVs for a few euros, and most of the time (8-9 over 10) there is only one broken capacitor that need replacement. He makes maybe one hundred euros every month by doing so, with really little work.
  - ryanwaggoner 7y ago
    I have only a rudimentary understanding of electronics and what the various components do, so this may be a dumb question, but how on earth do you diagnose an issue like this? If my monitor dies or my printer stops working and I open it up, I’m completely bewildered at what steps you’d take to figure out that some random resistor or capacitor out of (what seems like) thousands of components is the one causing the issue. Do you just go through and test each one with a multimeter until you find it?
    - jabl 7y ago
      Faulty capacitors often bulge, so you can find them by visual inspection.
      - userbinator 7y ago
        Bulge, or even just burst open and start leaking: https://en.wikipedia.org/wiki/File:Al-Elko-bad-caps-Wiki-07-02-17.jpg https://en.wikipedia.org/wiki/File:Al-Elko-bad-caps-Wiki-07-...
    - zeta0134 7y ago
      That's the general idea, yeah. I always start with the power supply because that part is under the most electrical strain, and tends to get hot. That means its components are often both the first to fail, and the most likely to cause weird problems when they do fail. Other than that, it's just intuition about how I think the device probably works, and a lot of trial and error. Major bonus points if there's a datasheet available, or a kind forum poster has had a similar problem to give me a lead on where to look.
    - bradstewart 7y ago
- ryukafalz 7y ago
  You should check out Louis Rossmann's videos on YouTube - he does exactly this. This one's not on his channel but is a good example: https://www.youtube.com/watch?v=g0S1ku9xvDI https://www.youtube.com/watch?v=g0S1ku9xvDI
- jdnenej 7y ago
  I have seen videos of people buying in batches of broken game consoles and replacing USB connectors and charge controllers since they often break and are not too hard to replace with the right tools. I also spoke to someone from Russia who worked as a electronics repair person fixing things we would normally throw away because the price of new equipment is very high compared to the price of an expert's time to fix it.
lettergram 7y ago
That might be fine if they can produce them cheap enough... I’m sure the same arguments were said when the CPU switched to having non-repairable transistors
richdougherty 7y ago
There is this section, which acknowledges the problem of replacing components: "We also need to consider system reliability. If a dielet is found to be faulty after bonding or fails during operation, it will be very difficult to replace." Their proposed solution (which is not repair): "Therefore, SoIFs, especially large ones, need to have fault tolerance built in. Fault tolerance could be implemented at the network level or at the dielet level. At the network level, interdielet routing will need to be able to bypass faulty dielets. At the dielet level, we can consider physical redundancy tricks like using multiple copper pillars for each I/O port." Your point is still valid, just wanted to call out their their thoughts on the issue.
- nine_k 7y ago
  Big CPUs / GPUs already have physical redundancy, and a way to cut / rewire a limited amount of faulty parts by laser etching in the die, prior to packaging.
  - monocasa 7y ago
    Cell processors are interesting because they do quite a bit of binning on a user facing SPI slave. You shift a thousand or so bit payload into it from a support/binrg up processor that tells it which pieces are disabled, how the PLLs are configured, etc. Hacked PS3s could reenable the binned off 8th SPE for instance.
- jdnenej 7y ago
  That doesn't seem to solve the issue of when a chip fails all together. While difficult, it's not impossible or unheard of for people to replace chips on a PCB like a charge controller that has fried.
- BAReF00t 7y ago
  It’s not just about faults. But about customizability and upgrades! I like to choose how much RAM and storage and which ports I want with how many generic, vector, FPGA and neural cores, thank you very much. And I like to change them later, to upgrade gradually. Even buses.

tartavull 7y ago

You can order custom pcb from China for a couple of dollars. How likely is that this technology will be affordable at small quantities?

jabl 7y ago
Seems one of the main advantages is higher density of conductors and connectors compared to a PCB. Aligning those dielets with micrometer precision would seem to require equipment out of reach for the hobbyist. And then bonding them, while they don't use solder but rather temperature and pressure, again with such small connectors I guess the line between bonding and destroying the thing is very very fine. Again requiring specialized and presumably expensive equipment.
Insanity 7y ago
First of all, I'm no expert (at all, I stay firmly on the software side of things) but here's my 2c: I'm going to guess that when PCBs were introduced, you couldn't get them for a couple of dollars from China either. These kind of things tend to become cheaper over time, as manufacturing, competition (newer or competing components) and availability grows. So I assume it's at least possible that at some point, a few decades from now, they're cheap :)

korethr 7y ago

I kinda like this idea, but I think it only makes sense where the end product sold to the intended consumer is wholly integrated. So, this might make sense for a smartphone. Or perhaps custom systems in Google- or Amazon- scale datacenters, with a number of different custom types tuned to exactly the work each is intended to do, and packed as densely as the intersection between thermodynamics and economics will allow. But, I don't think we can escape the need for packages and PCBs entirely. At some point, you're going to need to interface with something that either A) you don't or can't control, or B) something at appropriate scale for interfacing with the humans whom the fancy system is ultimately supposed to serve. In either case, here come standard connections that are much bigger than the chiplet dies or the interconnect fabric between them, and thus, the need for PCBs to connect the Systems-on-a-wafer to the outside world. As such, I think it will be a while before I can pick components out on Mouser's website, and have all those component chiplets fused to an interconnect wafer and delivered to my home or employer's shipping dock (though that would be damned awesome).

gumby 7y ago
> As such, I think it will be a while before I can pick components out on Mouser's website, and have all those component chiplets fused to an interconnect wafer and delivered to my home or employer's shipping dock (though that would be damned awesome). I agree. People have been talking about that future since at least the 1990s (back then SOC didn't mean a somewhat standard chip with a lot of peripherals, but literally a custom die with your own hardware on it). "Hardware/software co-design" was part of the jargon of the day. I'm not holding my breath. But I do imagine seeing a lot of consumer products go this way. Not a $3 IoT light switch/malware vector, but anything that gets rid of connectors is a win on both the BOM and reliability standpoint, but anything in the $50-$500 price range with volume over a million units is probably worth it.

jpm_sd 7y ago

"Power turned out to be a major constraint. At a chip’s standard 1-volt supply, the wafer’s narrow wiring would consume a full 2 kilowatts. Instead, we chose to up the supply voltage to 12 V, reducing the amount of current needed and therefore the power consumed. That solution required spreading voltage regulators and signal-conditioning capacitors all around the wafer, taking up space that might have gone to more GPU modules." Uh, this seems like a pretty serious downside.

deleted 7y ago
[deleted]
jjoonathan 7y ago
Also: shifting PCB prototype costs in the direction of silicon is going to be a tough sell for many applications. > Another drawback of SoCs is their high one-time design and manufacturing costs, such as the US $2 million or more for the photolithography masks > ... 6 paragraphs later ... > Patterning wafer-scale Si-IF may require innovations in “maskless” lithography.
willis936 7y ago
Resistive losses are that high? The signal integrity issues are going to cause unacceptably high error rates.
baybal2 7y ago
Silicon's limit is 0.7V and there is no trick against that. No matter how efficient is your power supply, you will be losing electricity very very rapidly within single centimetres. That's why there is no way to work around the need to move the voltage conversion on chip. In the future we may even increase IC voltage to reduce the copper losses for very low power, but huge devices.

holy_city 7y ago

I like the idea of faster and smaller devices but dislike the idea of expensive production methods that are only realizable with heavy capital investment and large volumes of products. Like I can realize a PCB prototype in my apartment (or rather, my parking lot without telling my landlord), or rent a CNC machine at a makerspace/public library to do it. If I need the thing fabbed with a nice solder mask and silk screen, I can have it made for < $20 domestically with under two weeks lead time. Component sourcing is even easier. But where do I go to have the chiplets I need for the circuit? Organize the logistics to ship them to the clean-room where they can be packaged on this fabric? How many widgets do I need to ship for this to be viable, or for the contract fab to not laugh at me? How do I prototype? How long is the lead time? It just seems like there's a lot in the way of this being viable for run of the mill projects.

jabl 7y ago
Increasing capital costs and consequent dependence on huge volumes have been a defining feature of the semiconductor industry since the invention of the integrated circuit. AFAICT this technology will have no impact on the low end hobbyist end of the market, but rather (if all works out) enables those $zillion behemoths to produce ever faster systems since they won't be as bottlenecked by off-chip bandwidth as they are with today's PCB's.
BAReF00t 7y ago
You’ll need $2 million, just for the mask. And if you want to fab yourself, the machines cost in the range from $10 to $50 million. For one machine. And you will need many. As the article states, you will not make those at home any time soon, unless ”maskless“ fabbing becomes a thing.

cphoover 7y ago

Will this increase the number of bit flips from cosmic rays?

brootstrap 7y ago
All the cool kids these days are _wearing_ nodeJS , not just writing it!

craigjb 7y ago

It's been fun to see Dr. Subu present this concept and prototypes at several conferences, and the level of integration possible is absolutely insane. I think the industry is definitely moving toward chiplets, such as the latest AMD release. I definitely think we will see more chiplets and more standardization on interfaces between chiplets. The focus will be on how to minimize energy per bit transferred (a big topic in Subu's talks) and how to minimize the die area used for inter-chiplet communication. In monolithic silicon, you don't have to think about die area, since your parallel wires between sections might just need a register or two along the way. With chiplets, you typically can't run wires at that density yet, so you still have some serialization/deserialization hardware. But, since it's not crossing multiple high inductance solder balls and PCB traces, you can get away with less. Hopefully also you can get away without area-intensive resynchronization, PLLS, etc. I think it will definitely be awhile before this kind of integration is used outside of niche cases though. The costs are just insane. You have to pre-test all manufactured chiplets before integration, and that test engineering is nothing to sneeze at. If you don't then you have all kinds of commercials issues about who is liable for the $500k prototype one bad chip broke. On the bright side, I see the chiplet approach benefitting other integration technologies. For example, wafer level and panel level embedded packaging technologies can be used for 1-2um interconnects now. You won't get a wafer sized system out of it with any kind of yield, but it's probably the direction mobile chips and wearables will go. Anyway, disorganized info-dump over.

jabl 7y ago
I agree this looks promising, though I'm not an expert in this field. But the title is a bit, well, overpromising or broad. I don't think we'll replace traditional motherboards anytime soon (except maybe in smartphones?). Rather, it will be an incremental progress. - first, SoC's will be replaced with chiplets - then we'll start seeing more and more stuff being integrated on this wafer. - say, instead of a server motherboard with multiple sockets, have all the CPU chiplets on the same wafer and enjoy much better bandwidth than you get with a PCB - integrate DRAM on the wafer. This will be painful as we're used to being able to simply add DIMM's, but the upside is massively higher bandwidth. The motherboard pcb per se will live for a long time still, if nothing else then as the place to mount all the external connectors (network, display, pcie, usb, power, whatnot).

cududa 7y ago

Color me skeptical, but I remember being 12 seeing this on The Screen Savers on TechTV in 2003

ChuckMcM 7y ago

This step is inevitable in my opinion. This is especially true for mixed signal (that is some digital and some analog components) systems. It's early fore-bearer (multi-chip modules or MCM) was instrumental in IBM getting its later mainframes to hit the density and thermal constraints. Like the authors, when I saw AMD's chiplet pictures for the Zen2 chips I felt that we would see this expanded. Intel has also done some interesting optical chip to chip interconnects that would facilitate assembling these newer multichip modules into chassis that route signals to and from the outside world. The next (and perhaps last) element to fall into place is a way to efficiently cool these systems. One of the problems that large data centers face is not that they want "smaller" boxes but that they need to pull enough heat out of a rack of servers in order for them to reliably function.

jabl 7y ago
For data centers, while air cooling might be running out of steam, there's plenty of leeway in water cooling. So I don't think that's an insurmountable problem.
- ChuckMcM 7y ago
  Having been inside Google's data centers I agree with you :-). I did a top level, high efficiency data center design for a multi-tenant hosting with Google scale economics as an exercise once, talked with some potential partners who were very enthusiastic. It would cost roughly double what the existing warehouse type data centers cost to build, but it would repay its costs faster than they did (given colocation cost structures at the time). It also leveraged some of the open compute designs to achieve better density.

Causality1 7y ago

>pack dozens of servers’ worth of computing capability onto a dinner-plate-size wafer of silicon. Congratulations on the insurance money from your building burning to the ground.

seltzered_ 7y ago

“Silicon-interconnect fabric, or Si-IF, offers an added bonus. It’s an excellent path toward the dissolution of the f(relatively) big, complicated, and difficult-to-manufacture systems-on-chips that currently run everything from smartphones to supercomputers. In place of SoCs, system designers could use a conglomeration of smaller, simpler-to-design, and easier-to-manufacture chiplets tightly interconnected on an Si-IF.” Reading this reminded me of a remark from Bunnie Huang’s teardown of a dirt cheap ‘gongkai’ cellphone (https://www.bunniestudios.com/blog/?p=4297 https://www.bunniestudios.com/blog/?p=4297): “To our surprise, this $3 chip didn’t contain a single IC, but rather, it’s a set of at least 4 chips, possibly 5, integrated into a single multi-chip module (MCM) containing hundreds of wire bonds. I remember back when the Pentium Pro’s dual-die package came out. That sparked arguments over yielded costs of MCMs versus using a single bigger die [...] I also remember at the time, Krste Asanović, then a professor at the MIT AI Lab now at Berkeley, told me that the future wouldn’t be system on a chip, but rather “system mostly on a chip”. The root of his claim is that the economics of adding in mask layers to merge DRAM, FLASH, Analog, RF, and Digital into a single process wasn’t favorable, and instead it would be cheaper and easier to bond multiple die together into a single package. It’s a race between the yield and cost impact (both per-unit and NRE) of adding more process steps in the semiconductor fab, vs. the yield impact (and relative reworkability and lower NRE cost) of assembling modules. Single-chip SoCs was the zeitgeist at the time (and still kind of is), so it’s interesting to see a significant datapoint validating Krste’s insight.” I wonder if there’s any advantages to si-if from an ewaste (aka reverse logistics, cradle-to-cradle) perspective

localhost 7y ago

Does anyone know how this compares with AMD's Infinity Fabric? How is it similar or different from it?

osamagirl69 7y ago
Infinity fabric is a software thing (a way to distribute information over a buss similar to pci-e) where as this is a physical piece of hardware that electrically passes the signals between 2 chips. I see no reason why infinity fabric could not be routed through a silicon interconnect, but it would be wasteful. The whole point of silicon interconnects that the hardware protocols like pci-e are no longer necessary and can use much lower power/cheaper ways to transfer data.

mhb_eng 7y ago

For reference, there are companies that have developed this to a commercially viable level. First that comes to mind is ZGlue, a company that has the design tools, interconnect fabric, and chiplet ecosystem required to deliver these kinds of devices. https://www.zglue.com/ https://www.zglue.com/

jpm_sd 7y ago
This is really impressive work.

bArray 7y ago

Yeah... I'm not entirely convinced about this future. * PCBs are cheaper to manufacturer than silicon wafers. * PCBs can be arbitrarily created and adjusted with little overhead cost (time and money). * PCBs can be re-worked if a small hardware fault(s) is found. * PCBs can carry large amount of power. * PCBs can help absorb heat away from some components. * PCBs have a small amount of flexibility, allowing them to absorb shock much easier. * PCBs can be cut in such a way as to allow for mounting holes or be in relatively arbitrary shapes. * PCBs can be designed to protect some components from static damage. What I can see on the other hand is some packages end up being dropped into the PCB and soldered at the sides. Sometimes this is done with large through-hole capacitors, where the legs are bent and the capacitor sits in the middle of the PCB (inside a cut hole). Other than ball packages, you could could probably drop the majority into the PCB itself. The other obvious option for manufacturers will be to put more tech on a single die, but then other problems are also raised. For example, some parts are binned based on their tested results.

userbinator 7y ago
What I can see on the other hand is some packages end up being dropped into the PCB and soldered at the sides. That's been done for at least 30 years: https://www.keesvandersanden.nl/calculators/hp32sii_repair.php https://www.keesvandersanden.nl/calculators/hp32sii_repair.p...
- bArray 7y ago
  That's amazing and I'm glad that it's possible, even by the standards of older technology. I certainly think dropping packages into the PCB is the lowest hanging fruit for reducing depth.
willis936 7y ago
I’d like to add onto your list: * PCBs can act as integrated antennas. * PCBs can easily mount connectors.

Yaa101 7y ago

The downside is that independent entities are not anymore able to design hardware projects, there are only a few companies that can design and make such integrated circuits. Cpu's are not only made for computers but for all sorts of appliances. Time will tell if these big companies will sell chiplets and the tech to assemble them onto silicon to 3rd paties. PCB tech is fairly democratic in that sense.

jabl 7y ago
I think it's more fruitful to (initially at least) see this as an alternative to single chip SoC's rather than an alternative to PCB's.

a0zU 7y ago

It seems like promising technology but the cost of making these chiplets must outweigh their benefits.

ColanR 7y ago

It sounds like hardware side of computer science is rediscovering the UNIX philosophy - each unit does one thing, well, with standardized interfaces.

NetOpWibby 7y ago

Cyberpunk 2077, here we come!

BAReF00t 7y ago

Gloodbye customizability and modularity, from a user standpoint. I guess Apple will hire them pretty soon.

wand3r 7y ago

I think it should be called Silicon Fabricated Interconnect so we can just call it Si-Fi...

josebogado 7y ago