SD Card data recovery

[cumbsie]

Hello,

I'm trying to repair an SD card that was given to me and I need advice. I thought it was just a solder bridge that was causing it not to function but when I removed the memory module with some chipquik it appears that some traces were pulled up at some point.  Is this board repairable? Can I transplant the memory chips to another board? Would it have to be the same make/model, same size etc. or would any SDHC board do?



Thanks.

[RDC]

You need a bit better pic than that for anyone to recommend a repair method.

If you're going to do a chip swap, you'd want to use the same type and brand of SD card for the best chance of that working. While most of those memory chips are all the same and use similar controllers, unless you dug into the datasheets for all of those there, as well as the ones on the SD card you were using for the transplant to make sure everything was the same, you could damage something.

I'm not seeing anything from that pic that can't be repaired with a few well placed, and tiny, jumper wires, especially if there are no components on the other side and the vias are not blind. But again, the detail can't be made out from that pic, so it could be worse than what I'm seeing.

It also really depends on how this card was damaged to begin with if that's even worth trying to fix of not. If it was subjected to a really harsh bend where the case cracked, then the PCB and chips took the same bending and could have broken vias or traces on the board that you'd never see, or bond wires in the chips to damage of the silicon inside it, so you could be doing all of this for not, hard to tell without knowing the history of the card.

[FOOKz™]

What is your end goal?

Repairing the SD card or plain data recovery?

If you're doing data recovery you can definitely pull the data from the chip with a donor SD card.
A full repair is not worth your time.

You could sacrifice a new identical SD card as a donor. Then desolder the memory chips from the new donor SD card in preparation to receive the memory chips that need recovery.


Your thoughts RDC?

[RDC]

Depends on the cards history. If it was bent really bad one or both of the chips could be bad, in which case no matter what you do it's all for nothing. If you're just after saving the data from it, and it wasn't bent to the point of breaking, jsut ahd the contacts messed up or something to where it didn't work like it's supposed to, then I'd just see about wiring it up as is to recover the data from it.

Repairing it for daily use or for use in some device is pretty much pointless compared to the cost of those things now, plus the solder that is all over the contacts on that side now would make that a sooner rather than later fail point.

[cumbsie]

I'm simply after data recovery. Sorry for the bad pictures, but I think this is the best I can do:







So do I just scrape the mask off with a xacto knife? I haven't worked with these flexi-type boards before.

[RDC]

That's not FPC (Flexible Printed Circuit), it's still a PCB, just very, very thin.

Those pics are much, much better, but you still can't make out what pads 26, 27 and 28 actually were, so I looked up the DS for that NAND chip.

Pad 25 will need repaired/connected, it's Vssq2.

Pads, 26, 27 and 28 you can leave alone, they are NC or DNU (Not Connected or Do Not Use).

Pad 29 will need repaired/connected as it's DQ0. 

Pads 30 on up look fine, but I can't see if there might be a hairline crack at the trace where it meets the pad from those pics.

Take some solder braid to those all of pads to clean them up first, or flow fresh solder over them all with some flux so you get rid of all the shorts. Be very careful while doing either of those, as you don't want to remove any more pads during the cleaning process.

If you get in any deeper, accidentally bodge something up or don't want to try going any further consider sending it to me, as I'd like to have a go at it. Kind of reminds me of the 360 days when sometimes a person would just wreck the chip on their drive trying to get a the pins, destroying the pins and most pads/traces in the process...



..and the only way to get the key off was to do this...

[cumbsie]

Do you think I might have to end up wiring every pin like in your picture.. :/

I cleaned up the card and took care of the shorts.



So would I scratch off where I have it indicated in yellow and solder the jumpers wires there? My only concern with that would be is the chip wouldn't be sitting perfectly level and that might cause problems.

[RDC]

You have the pad numbers wrong, 30 is really pad 25.

This is right side up, how your board is in the picture the top edge is really the bottom, the V notch on the silk (the white lettering and lines) denotes the package orientation. The V there is the top edge, and pin/pad 1 would go to the left of that.

Code: [Select]

-----------V-----------
1                       48
2                       47
3                       46
-                        -
-                        -
22                      27
23                      28
24                      25
 ------------------------

You're nowhere near needing to get to the level that I had to with that thing, unless you're missing the leads on the chip already?

I wouldn't put the wires there personally, as that will jack up that whole side. You could do that fix a couple of ways really.

1 -  The technically easier to do. Prep the Vias on the back of the board for those spots, and then just come around the edge to hit the leads of the chip. That way it will still sit flush on the board for every other connection. Since you only have those 2 to deal with it's the faster and easier way.

2 - More difficult, as if you botch up a lead you may be grinding into the epoxy to recover the connection. You have a fair amount of pad still left at each of those spots, so you could tack a a very thin wire to each pad, smaller than 30awg for sure, something like the single strand from a braided cable that has very fine strands. Then you'd have those 2 pins that would be bent up very, very carefully and ever so slightly to reinstall the chip and then solder it, making sure to not over heat it and desodler the end that is attached to the pad.

I'd honestly go for method 1, as you're just after recovery, and looks or space constraints aren't any issue. Method 2 is more for that kind of repair and is by far more difficult.

[cumbsie]

Method 1 sounds good to me. So just scrape with an xacto knife, flux and tin?

Is this where I want to solder the wires to?

[RDC]

Correct on both counts, just be careful, as there isn't exactly a lot of copper there to dig into.

[cumbsie]

OK. I've got everything wired up and it seems to work but it says the card must be formatted before I can access it. I haven't tried formatted it yet. 

I will definitely use magnet wire the next time I attempt something like this. Do you think something could be shorting causing the file system to appear as corrupt?

 

[RDC]

It's hard to tell what could be doing that, some wiring issue or the data on the card was corrupted from connecting it while some of those traces weren't connected. You should try to run some recovery software on it first now that the thing at least shows up.

If that fails, I'd probably hot air off both chips, look for any hairline cracks and then reinstall and rewire it, but I'm tenacious when it comes to issues like that.

I use ZAR X here, but there are loads of free tools you can try on it.