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CPU upgrade x10


zzattack
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Tomorrow I'll add some pictures. I've prepared a jig for reballing the 9 interposers I still have, since placing the balls by hand just once, however humbling the experience may be, just isn't for me. For that I used a regular stencil with the unused pads masked using kapton tape. Pics will clarify.

I'll also add some info for the paste dispenser that I used, although I prefer having a stencil made instead. 

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38 minutes ago, zzattack said:

Tomorrow I'll add some pictures. I've prepared a jig for reballing the 9 interposers I still have, since placing the balls by hand just once, however humbling the experience may be, just isn't for me. For that I used a regular stencil with the unused pads masked using kapton tape. Pics will clarify.

I'll also add some info for the paste dispenser that I used, although I prefer having a stencil made instead. 

Nice!, Yeah free hand reballing is ugh yeah.  Cpu with kapton tape to preball adapter I think I got down.  Can't wait to see your stencil ideas for top part of adapter, will order solder paste gun if have to.  How precise are the solder paste syringes?

Edited by Donnie-Burger
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I was actually looking at the ACHI IR6000 as my first unit. Iˋm just worried about aligning the interposer by eye. Not looking forward to that at all... that and programming the heating profiles into the unit. Any guidance on alignment?

I thought I would be putting CPUs in Xboxes by now, but life circumstances keep putting it on hold and it sucks.

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16 hours ago, Donnie-Burger said:

Nice!, Yeah free hand reballing is ugh yeah.  Cpu with kapton tape to preball adapter I think I got down.  Can't wait to see your stencil ideas for top part of adapter, will order solder paste gun if have to. 

Jig idea: generic stencil for 0.76mm balls at 1.27mm pitch, with unused pads masked off using kapton tape. Since the interposer boards are 1.6mm tick, I surrounded it with PCBs of identical thickness, secured onto an ABS sheet with (thin) double-sided tape.

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The interposer squeezes firmly in between the surrounding boards. A few overlaying strips of kapton briefly elevate the stencil. This gives the stencil some vertical clearance for the balls to fall through, and ensures the flux on the board doesn't touch the stencil. Regardless, I highly recommend cleaning off the stencil after every board for the best results. If balls don't fall through on the next one, you should've cleaned it.

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After pouring on the balls, I use a very soft ESD brush to spread the balls. They balls are not encaged so I used a very light touch, or else I'd be finding solder balls all over the place for months.

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With the balls placed, lift the stencil and manually repair any imperfections. You can see the bottom-left ball didn't make it. After having worked on some 0.2mm BGA stuff recently (not fun), manually placing 0.76mm balls is no longer any issue, even for pads that have 8 surrounding ones.

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On to the hotplate for attaching them. I highly prefer IR over hot air because the balls don't move. With hot air, if you have just the tiniest bit of excess flux, balls start drifting freely.

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Repeat... and after about 2 hours the work came to an end. Surely there's better ways to spend your Saturday but ultimately, it's good to have it done.

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16 hours ago, Donnie-Burger said:

How precise are the solder paste syringes?

Not perfect, but with a small (say airbrush) compressor and simple paste dispenser you can place drips very quickly, with reasonable accuracy, and reasonably similar amounts of paste. So I'd say it's fine.

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17 hours ago, Bowlsnapper said:

I was actually looking at the ACHI IR6000 as my first unit. Iˋm just worried about aligning the interposer by eye. Not looking forward to that at all... that and programming the heating profiles into the unit. Any guidance on alignment?

I thought I would be putting CPUs in Xboxes by now, but life circumstances keep putting it on hold and it sucks.

I'd recommend the ACHI for sure.

Aligning the interposer isn't too hard. The top end of the board nearly touches a capacitor on the top. For the horizontal alignment, just turn the interposer over, align the balls by eye and rotate the board around while keeping the same lateral position, then shove it up to that capacitor. The good thing about BGAs is that you're still fine even if you're just under half a pitch off. That's 0.6mm of margin!

 

While everything up until now has been smooth sailing, I've ran into the first snags today. An eBay package with Tualatins arrived, and even though I ordered only 2 from the seller, I actually received 3. Sadly, one doesn't work. Not a loss overall, but still, this kinda indicates there's bad CPUs out there. I'm now glad that I purchased a socket 370 motherboard solely for testing.

The other problem I ran into today manifested on two boards: the interposer tilted when soldering it down. I didn't initially realize this on the first board and have already soldered on the CPU there, but obviously the system FRAGs. Inspecting very closely under the microscope reveals that only the very corner ball is floating over the motherboard. The balls just 1 pad closer to the center have soldered but they are obviously not ideally squashed. Reason for this must be that the weight of the interposer board rests only on the BGA balls, but the board protrudes over the BGA area. I'll have to remove the CPU and reball this one unfortunately.

I set this board aside before making this realization, and soldered a 2nd interposer on another motherboard. Close inspection of that one showed the clearance between interposer and xbox wasn't perfectly even, and pressing in the corners flexes the board slightly. Will have to reball this one as well, but this gave me an idea for a fix. The 0.76mm balls when soldered down are roughly as thick as 0603 passives. The board is already resting on a set of 4x 10k 0603s on one side, so we can use such 0603's to support the board in the far corners. I soldered 2 resistors with one end to via's near the corners so they won't slip away, but they serve no electrical function of course. I then continued to attach another interposer to this 3rd board and it came out perfectly. There's zero flex, the balls are squashed very nicely, and the clearance is perfectly even around all edges. I'm confident that the issue's found and remedied, and I'll verify that tomorrow if my wife lets me on Mother's Day :)

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On 5/7/2022 at 12:45 AM, Bowlsnapper said:

I was actually looking at the ACHI IR6000 as my first unit. Iˋm just worried about aligning the interposer by eye. Not looking forward to that at all... that and programming the heating profiles into the unit. Any guidance on alignment?

I thought I would be putting CPUs in Xboxes by now, but life circumstances keep putting it on hold and it sucks.

I would say if you can, get an IR-PRO-SC over the 6000, it will give you the ability to work on more consoles if you'd like down the road. I have one myself and been doing tons of PS3's recently. I can help you with a rough profile setup from what i've been using for my reballs!

 

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7 minutes ago, shawnunderse7en said:

I would say if you can, get an IR-PRO-SC over the 6000, it will give you the ability to work on more consoles if you'd like down the road. I have one myself and been doing tons of PS3's recently. I can help you with a rough profile setup from what i've been using for my reballs!

 

Seems like the ir6500 replaced all of those models.  They are $600 on amazon.  Anyone one if they are any good?

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Time for a minor update. Not a very happy one just yet but new ideas for improvement did spring to mind, so I'll use this post to share some ideas I had.

First, I believe @Bowlsnapperhad some concerns about aligning the interposer to the board "blindly". There's no need to go in blind, in fact, we can make it foolproof. I measured the silk screen print accuracy on the adapter and on the motherboard with a digital caliper. There's only about 0.1mm difference in outline width/height between the interposer and console boards. They're also accurately spaced around the solder pads, meaning this outline actually makes for a pretty decent calibration opportunity. What you can do it apply some kapton tape along the silkscreen outline on both the board and the interposer. Then, just make sure the tape aligns, and you're guaranteed a very reasonable alignment.

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And then you just overlay the crosses:

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When soldered down, it's probably still quite possible to remove the tape by pulling it down and wiggling it out. Or you can just cut it near the sides, no big deal either way.

 

I'll use this method to verify my split vision system's accuracy on my next attempt. Since I'm not picking up the interposer in dead center, I'm no longer convinced the placement is as accurate as the visual indicates. This will either confirm my suspicions or rest my mind.

 

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As I laid down in bed I couldn't contain my curiosity since I was still so perplexed that the 3 attempts after my initial successful one failed. I needed to check. The first board I used was a 1.4, the others were 1.0. Could there be a big difference in alignment between them? The top of the board sits very close to an SMD cap. You judge!

 

On a 1.4, it's close but it fits:

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On a 1.0, oops, that'll elevate the interposer and certainly not benefit the soldering quality:

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I'm fairly assured this caused the poor BGA alignment. And so we learn. More later this week.

Edited by zzattack
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You could look at getting a stencil made by PCBway.  Annoying thing I had free access to a big box of FPG CPU stencils years back that were being trashed. Didn’t take it as back then didn’t have any abilities to rework etc.

so annoying. Was right around the time when the XBox cpu was current tech.

 

 

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On 5/4/2022 at 5:09 AM, zzattack said:

Last week I purchased a nice OG to revisit a console that I'd had so much fun with 2 decades ago and to do some modding on. I set out to finally recreate one of those Friendtech/trusty/n64freak consoles that I'd wanted to do for a long time, but unfortunately never followed up with. This was made infinitely simpler after n64freak opened up sales of his bare interposer boards, so now the daunting amount of work for engineering these boards myself from the Friendtech patent file and datasheets can be skipped.

I sourced the components for the clock switching circuit on the interposer, which totaled an astonishing €5 from Digikey, while I needed to spend €50 to qualify for free shipping. This quickly spiraled out of control, I ordered everything x10... There's another 10 CPUs coming my way and there's a 10-high stack of never-been-opened xboxes behind me already.

While awaiting components to arrive, I've been reading about this upgrade and this left me the impression that these CPU-upgraded consoles at some point were highly sought after. I'd like to gauge current interest and am trying to get global idea of what these units should yield when sold. I was thinking of offering the following for €275:

- Clean motherboard with CPU upgraded to a 1.4GHz/512kB cache Tualatin using n64freak's interposer
- RAM upgraded to 128MB by installing the 4 additional chips
- OpenXenium modchip installed (or only with a flashed BIOS for some discount)
- no PSU, HDD, DVD, case since cost of shipping twice easily exceeds sourcing an xbox locally for most locations

I still have to think about a proper reliable solution for the heatsink if these boards are to be shipped.

Any thoughts?

I would buy two to four of these. US based but don't mind extra taxes/fees.

Edited by cyrix
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On 5/9/2022 at 2:58 PM, zzattack said:

As I laid down in bed I couldn't contain my curiosity since I was still so perplexed that the 3 attempts after my initial successful one failed. I needed to check. The first board I used was a 1.4, the others were 1.0. Could there be a big difference in alignment between them? The top of the board sits very close to an SMD cap. You judge!

 

On a 1.4, it's close but it fits:

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On a 1.0, oops, that'll elevate the interposer and certainly not benefit the soldering quality:

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I'm fairly assured this caused the poor BGA alignment. And so we learn. More later this week.

Theoretically, you should be able to relocate that SMD cap and just use tiny-ass gauge wire to link it to the pads it was soldered to. 

ZZ, you are the shit, man. Iˋve been hoping that somebody with an enthusiasm and drive for CPU upgrades would show up... and with knowledge of BGA stuff. I will probably ask you a LOT of questions over the next few months. Hopefully, I wonˋt become a nuisance.

Interesting suggestion with the tape. Thanks for that. :)

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On 5/9/2022 at 11:06 AM, shawnunderse7en said:

I would say if you can, get an IR-PRO-SC over the 6000, it will give you the ability to work on more consoles if you'd like down the road. I have one myself and been doing tons of PS3's recently. I can help you with a rough profile setup from what i've been using for my reballs!

 

How would you compare it to the 6500, like DB mentioned?

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  • 3 weeks later...

I've put the conversions on hold for a little while since my installs after the first successful one didn't work no matter what I tried. Cleaned up my soldering profiles, ensured my alignment was dead on, sought help from very knowledgeable people including N64 himself, to no avail. At some point I stopped counting, but I believe I registered 9 or 10 failures and decided to take a step back, since the time wasted for no results became a source of frustration.

Uploaded some pictures here: https://imgur.com/a/z0YPuoN

Ultimately I decided the sensible continuation would be to employ an x-ray device to verify correct soldering of the interposer. I found a dental device that I could accommodate with my budget and the device has since arrived. The sensor area is small (21x21mm) but resulting images are surprisingly usable. Can't tell for sure if this will allow detection of voids or head-in-pillow easily, but certainly I can identify spots where the balls floated slightly. I will adjust the interposer reflow profile to remain above liquidus slightly longer. More updates soon!

 

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x2.png.17f4e4579669279c0a5acf65a6f2d83d.png

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6 minutes ago, zzattack said:

I've put the conversions on hold for a little while since my installs after the first successful one didn't work no matter what I tried. Cleaned up my soldering profiles, ensured my alignment was dead on, sought help from very knowledgeable people including N64 himself, to no avail. At some point I stopped counting, but I believe I registered 9 or 10 failures and decided to take a step back, since the time wasted for no results became a source of frustration.

Uploaded some pictures here: https://imgur.com/a/z0YPuoN

Ultimately I decided the sensible continuation would be to employ an x-ray device to verify correct soldering of the interposer. I found a dental device that I could accommodate with my budget and the device has since arrived. The sensor area is small (21x21mm) but resulting images are surprisingly usable. Can't tell for sure if this will allow detection of voids or head-in-pillow easily, but certainly I can identify spots where the balls floated slightly. I will adjust the interposer reflow profile to remain above liquidus slightly longer. More updates soon!

 

x1.png.dea90d838c6f8d1b79eb490e8c339e8e.png

 

x2.png.17f4e4579669279c0a5acf65a6f2d83d.png

I'm assuming these are x-rayed with cpu on?  Maybe xray after each step?  Very nice find bud and hope you figure it out.

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Didn't have too much time last night, but experimented with the idea of manually tenting via's within the BGA area.

I applied a thin layer of UV curable solder mask over exposed copper that wasn't part of any BGA pads, cured it, and then mounted an interposer. This appears to have prevented any bridges from forming between solder ball and nearby via. Ideally this wouldn't be necessary and I do intend to figure out how this happened in the first place, and how to prevent it from happening, but this appears to be a simple workaround.

I'll complete the install on this one tonight and hopefully book some success with it. It's about time.

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  • 4 weeks later...

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