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juiceme is offline juiceme
2020-04-29 , 06:27
Community Council | Posts: 4,920 | Thanked: 12,867 times | Joined on May 2012 @ Southerrn Finland
#21
I can assure you swapping components between N9 and N900 like that will not yield a working device. Or between just about anything you can try.
With motorcycle parts you can mix & match mechanical parts but with electronics it is a bit tougher; the pinouts are different and the components need the other components around them to work peoperly.

With electronics there is a simple rule-of-thumb; only replace parts with identical parts. (and of course because the rule is simple there are exceptions but if you need to ask, you are guaranteed to fail )
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Maemish is online now Maemish
2020-04-29 , 08:21
Posts: 1,702 | Thanked: 4,752 times | Joined on Apr 2018 @ Helsinki, Finland.
#22
I have understood the N9 processor could be put in N900. They are that close (check the models). It was just that it should be configured in the flashing image for device to know how to use that. I bet it could be checked from the N9 image what would need to be changed to what. But they should be swappable if I am correct and I usually am. The difficult part is to put the balls to right placed before heating the processor in place. They are that small.
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pythoneye2 is offline pythoneye2
2020-04-29 , 13:19
Posts: 110 | Thanked: 362 times | Joined on May 2014
#23
I love to break it to you

You underestimateing the difficulty of this.

This is way more complicated than most other devices not only because of small pin size and count. But because of ram and flash sitting on top of cpu. You get all sort of complicated warping. There was once a firm in Germany which was able to solder this configuration, but after they swapt some employes and some machines there were unable to pull this off economically.

The bad yield of gta04A5 second batch:
http://lists.goldelico.com/pipermail...ry/007262.html
http://lists.goldelico.com/pipermail...ry/007271.html


Neo900
http://talk.maemo.com/showthread.php?p=1525427

My guess is that the firm had better tools and more knowledge than you, but of course i would be happy to be proven wrong.
 

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Trzyzet is offline Trzyzet
2020-04-29 , 15:45
Posts: 68 | Thanked: 300 times | Joined on Mar 2017
#24
Originally Posted by pythoneye2 View Post
This is way more complicated than most other devices not only because of small pin size and count. But because of ram and flash sitting on top of cpu. You get all sort of complicated warping.
Ugh, sandwich SoCs are real crap. I remember times of Symbian phones, especially N73 which had that type of SoC. Absolute nightmare but I was soldering them by manually reball and fitting chips layer by layer. It's possible but needs a lot of time and focus. Nothing for mass production but one, maybe two units per day.
 

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pythoneye2 is offline pythoneye2
2020-04-30 , 21:57
Posts: 110 | Thanked: 362 times | Joined on May 2014
#25
Originally Posted by Trzyzet View Post
Ugh, sandwich SoCs are real crap. I remember times of Symbian phones, especially N73 which had that type of SoC. Absolute nightmare but I was soldering them by manually reball and fitting chips layer by layer. It's possible but needs a lot of time and focus. Nothing for mass production but one, maybe two units per day.
wow, thats work. How many tries did you need before you got your first working? How many did you mess up (ripped pins)? Did you have a stencil for reball? How did you test them?
 

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Trzyzet is offline Trzyzet
2020-05-01 , 01:39
Posts: 68 | Thanked: 300 times | Joined on Mar 2017
#26
Honestly, if device wasn't liquid damaged I ripped pads to the point which makes device unrepairable maybe 2 or 3 times in my quite long service career. But I was soldering for first time when I was 12, started to fix the mobiles when I was 16.

I soldered my first sandwich SoC (simple reballing because of the liquid damage, few pads was corroded and solder ball popped out from the chip) at second try, that was Nokia N73. Everyone in the service was astonished because device worked for first time. Later when there was more devices like this we had a lot of donor boards. We just limited ourselves to one try at unit.

Forgot to mention: I was using an universal stencil and good solder paste instead of balls. Good paste has also good flux so makes the process much easier. I'm using this method even today when I'm reballing some chips in macbooks, mostly RAMs and SMCs.
Last edited by Trzyzet; 2020-05-01 at 01:44.
 

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biketool is offline biketool
2020-05-01 , 09:07
Posts: 1,417 | Thanked: 2,619 times | Joined on Jan 2011 @ Touring
#27
Originally Posted by Trzyzet View Post
My tip - use some good solder flux for BGA, it will help to melt solder at lower temperature and also will clean some oxidized crap under the ICs. After that reflow cleaning will be ofc needed.
Flux gang reporting in!
Flux and temperature are the secret to effective soldering.
I once had the dubious honor of fixing an air band radio fishing up in Alaska with only flux made from pine tree sap and a hot nail(dropped it on rocks snapped off antenna, had to make a wire replacement and solder it to the board).
Flux makes soldering work and if you cant get solder to 'stick' it is probably an oxidized surface preventing the solder form flowing properly.
Once it is all done you can clean up the flux mess with high % alcohol.
Liquid flux or flux pen for hot air/oven flow in soldering though solder powder with flux paste is used to get surface mount things to 'self solder' down from the heat while the little boxes and tins are for through hold soldering with an iron.
 

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Trzyzet is offline Trzyzet
2020-05-01 , 09:19
Posts: 68 | Thanked: 300 times | Joined on Mar 2017
#28
Originally Posted by biketool View Post
flux made from pine tree sap
Rosin. Still used sometimes, especially by hobbyists. Smells nice

In a case you have no flux and components are big, you can use aspirin. Seriously works!
 

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pichlo is offline pichlo
2020-05-01 , 10:41
Posts: 6,445 | Thanked: 20,981 times | Joined on Sep 2012 @ UK
#29
Originally Posted by biketool View Post
Flux gang reporting in!


I once had the dubious honor of fixing an air band radio fishing up in Alaska with only flux made from pine tree sap and a hot nail
Wow, that's what I call hardcore! Did you get the sap from the actual pine? That's kewl!

In a case you have no flux and components are big, you can use aspirin. Seriously works!
I have never had much luck with aspirin. It absolutely stinks, boils too quickly, burns into a messy black mass and still does not wet the surfaces. It might be because for normal soldering I just use rosin and have resorted to aspirin only to try to solder things where rosin does not help, like aluminium. I've read that aspirin is supposed to help, but it did not in my case.

A drop of hydrochloric acid was supposed to work too, but I have not tried that. Not that I am too keen to breathe hydrochloric acid fumes
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zenecho is offline zenecho
2020-05-01 , 13:56
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#30
Wow, this is a great read
 

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