BGA socket allows RAM upgrades on SBCs | Hacker News Reader

BGA socket allows RAM upgrades on SBCs

cnx-software.com

31 pointszdw30 comments

This is... not really news? Yes, BGA sockets exist. Device programmers and development/evaluation boards often have them. Unfortunately they are not cheap, even direct-from-China:

https://siredatech.en.made-in-china.com/product/oSUJIjpOfwYD...

I guess maybe they could be made at more reasonable pricing in volume?

But you're right. I've needed to have small 100 BGA sockets before and typical pricing of non-standard parts was $2k for 4 with a $1k setup fee.

That's not an interposer; an interposer is a device that sits between a device and a board and breaks out the interface so that it can be probed with a logic analyzer or timing measurement equipment or something.

This looks more like a test fixture socket - those things cost more than the entire SBC does - so this seems more like a proof-of-concept rather than anything practical right now.

An interposer doesn't have to have any breakout pads or pins. It just needs to sit between a board and component. It can serve as a breakout for components that may or may not be compatible with the footprint on the board or may not break anything out at all. I've used one to substitute a much cheaper FPGA in for our very expensive one on the development prototype. We didn't need all the features while sitting on a test bench so we saved ourselves some money until a production unit could be our dev platform. We had a few breakouts on the board of some signals that were difficult to access elsewhere but most just routed right through the interposer. We also developed another interposer that replaced a bunch of deadbug components to prevent rework from occuring due to poorly placed deadbugs. There was enough money to get a little card made but not enough to respin the whole board with the wishlist of other changes we wanted to make.

To me, an interposer implies something that modifies the form factor, which this doesn’t. For desktop processors, the interposer takes the ultra fine pitch die and turns it into something that an LGA/PGA socket can take.

> While it looks neat, I’m not convinced we’ll see barebone single board computers where users can insert their own eMMC flash and RAM any time soon, since it would likely add to the overall costs. A more likely use would be for board vendors wanting to test RAM chips from various vendors and of different capacities.

Most SBCs use socketed eMMC chips available in various capacities. Pine64 and Odroid's eMMCs are compatible, at least, and live on a tiny little board you can swap out.

I don't see the cost and complexity as being worth it, though. Just stuff the things full of RAM, have lower capacity options, and solder it - same as we see today. Yes, it's nice on paper to swap the RAM out, but I guarantee these sockets aren't cheap, and for something that's used once or twice, eh. Not worth the hassle...

I like things that are easily repaired, but I also don't see a huge wave of ARM SBC RAM failures. They're already repairable, it just requires hot air rework and a bit more skill than swapping a DIMM.

"They're already repairable, it just requires hot air rework and a bit more skill than swapping a DIMM."

Where do I find people who can do that?

I google 'electronics repair London' and all I get are little shops where a dude with a screwdriver might replace a RAM stick, which I can do myself too! If I search for 'hot air rework' I get people trying to sell me kit. If an engineer can't find a place for such repair in the largest megacity on the continent, what hope is there for an average Joe?

Also for chromebooks and crapbook worth $200-$300, how is that rare person going to charge for his time?

Your last point explains your former difficulty. There’s no retail willingness to pay, but a lot of willingness to inquire and waste someone’s time. Start with an in-country PCBA firm; they’re likely to have someone or know someone.

Alternatively, inquire on an enthusiast forum (eevblog) or talk to your local Ham radio club.

The same reason no one is advertising this skill to retail buyers of $200 electronics is the reason to not include a spurious $2-4 socket.

$2-4? If only. This socket is more like $50-60 -- probably more expensive than the rest of the board.

https://www.aliexpress.com/item/1005001841972537.html

What would a (much more complicated) LGA 1200 socket cost if it wasn’t already a high-volume part? I can buy one for $85 and they’ll throw it in a retail box with a whole motherboard, multiple PCIe, DRAM, DisplayPort/HDMI/VGA connectors, Ethernet and USB controllers, as well.

"There’s no retail willingness to pay, but a lot of willingness to inquire and waste someone’s time."

I was willing to pay good money for GPU repair, sent out a few emails and heard back only crickets - maybe I wasn't looking in the right place, dunno. But yeah, repairing minor stuff might not be cost effective

> Where do I find people who can do that?

Your local hackerspace/makerspace is likely to have people who can do it, though I don't know how you'd find people who do it professionally. It's a bit of a weird niche, though as the supply chains continue to crumble I expect it to become a more popular one in the years to come. But if you can't find anyone who does it, perhaps there's an opportunity for you to jump into!

I expect this sort of thing to take the form of people who buy "broken, parts only" equipment on eBay/Craigslist/etc and fix it at their own location, on their own time, and then resell it, though. It's less likely to be a customer facing activity.

Look for mobile phone repair shops.

> Also for chromebooks and crapbook worth $200-$300, how is that rare person going to charge for his time?

I think you stumbled across the problem: troubleshooting and repairing the device will probably cost $200. If the device is under warranty, it's easier to send it back. If it's not, it's more cost effective to replace it.

It's not like you have to pay yourself $200 for repairing / upgrading your device. But this is quite rewarding and worth spending time on just for the feeling that you fixed something. Certainly I would prefer this than spending an hour watching Netflix.

It's probably not viable as business. You can buy a rework station for under £100 these days and it does not take up a lot space, so you could store it away in the storage among other tools needed but rarely used. I mean, for instance, my dad was never into electronics, but we had a soldering iron at home, just in case a wire needs to be redone etc. Times have changed and I see no reason why there shouldn't be a rework station in every home. Maybe the name "rework station" sounds misleading, like you would need a dedicated bedroom to use it... But to redo a couple of chips is no different than taking your blender from under the stairs to do a smoothie.

I'm sorry but searching 'hot air rework bga' leads to better results...

https://youtu.be/i9qC7x5QHIo?t=221

Don't forget that you must replace the solder balls on desoldered chips with a stencil. Your new bga chip should come with solder balls though.

Sorin[1] is based in some London repair shop. It is probably viable because he repairs cheap laptops among other things. He also takes mail orders, but I haven't seen him mention any contact info in his videos.

[1]: https://www.youtube.com/watch?v=yBYpyI6OW64

Part of my job involves working with engineering sample SoCs on development and characterization boards.

I've seen just about every kind of socket and connector you can imagine but I've never seen a BGA socket that is reliable enough to use in a normal machine.

They would never pass qualification use in a typical laptop.

I don't think the socket is even the issues these days. The new Mac Studio has M.2 style slots but they are useless as apple locks it all down in Software.

Wow, that's awesome. This kind of thing could possibly make Chromebooks and the like repairable.

What prevents you from repairing them now, exactly? Hot air rework stations have come down dramatically in cost, and there's no shortage of videos talking about how to do it. Try a few scrap bits before working on something expensive...

It's nice to be able to swap things out with sockets, and you'll generally find me coming down on the side of repairability, but it exists with a variety of other considerations, and something that is less repairable, but also far less likely to fail in the first place, may be a better option. Also, I rather like the fact that soldered on RAM makes things like coldboot attacks a lot harder to pull off if you're using trusted boot.

Heavy use of adhesives is certainly a problem, but I just can't get that worked up over soldered on RAM.

I don't have a garage to keep equipment that I will use once in 3 years, I don't have scraps to resolder and that's probably true for most people. For whatever reason a real repairshop is a lot harder to find than a laundrette - I was looking for one to fix a GPU, and I could not find one.

These sockets cost $60 a piece.[0] Four of them alone is already ~$250. Add manufacturer markup, and you’re looking at an extra $300 to the consumer.

If manufacturers want to make RAM replaceable, they should be putting SO-DIMM slots (which cost single digits),[1] not BGA sockets. After all, the average consumer is more likely to know how to procure RAM sticks than raw BGA RAM from DigiKey, Mouser, etc.

[0]: https://www.aliexpress.com/item/1005001841972537.html

[1]: https://www.digikey.com/en/products/detail/10033854-052FSLF/...

When I think about it it could certainly make layman repairing them cheaper. But I'm not sure if it really would chance too much with professional work, the parts and labour time would still be about the same or in same magnitude.

And how often does RAM fail anyway? Or if it needs to be upgraded what about other parts?

Even replacing an 0805 is a pretty significant challenge. I have no idea how people do BGAs with anything but a pick and place.

Plus, without x-rays, how do you know you got it right? There's a lot of ways something can have a weak joint that isn't immediately noticeable. And, unless you have CNC equipment the result is more art than science, the quality depends largely on your hands.

I wouldn't trust a device that had been repaired by anyone but an experienced pro, seeing as how these devices(along with phones) are the cornerstones of modern life.

What I've seen is: use a microscope is used to align the new part with the silkscreen outline. Get it good enough and turn on the heat. The part will self align as the solder melts.

Which is fine for single item repairs or upgrades where the person doing the work is tech savvy and all parties are will to accept the loss of a functional device in case something goes awry. (Which, admittedly, is rare, but you have to take the liability on yourself every time).

Something like that is entirely non-feasible for mass manufacturing of parts with any guarantee of quality though.

The GDPR popup on this site is pure dark pattern, try saying "no do not sell my data" and the next prompt auto-selects "yes sell my data" with a default button of "Allow".

What Fucking Trash.

For anyone who desires reading TFA without the crap salad sando:

https://web.archive.org/web/20220421034027/https://www.cnx-s...

https://archive.ph/180ug

As others have said it would be more productive to just support standard PC mainboard standards like DDR3 over SO-DIMM.

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