Nowadays a lot of modern NAND flash devices use a new type of architecture, where the interface, the controller and memory chips are integrated into one common ceramic layer. We call it Monolithic structure.
Until recently, all memory cards like SD, Sony MemoryStick, MMC and others, contained a very simple “classic” structure with separated parts – a controller, a PCB and a NAND memory chip in the TSOP-48 or LGA-52 package. In such cases, the full process of recovery was very simple – we just unsoldered the memory chip, read it in PC-3000 Flash, and made the same preparation as with common USB Flash drives.
But what should we do if our Memory Card, or UFD device is based on monolithic architecture? How can we get access to a NAND memory chip and read data from it?
Basically, in this case we should try to find a special technological pinout on the bottom side of our monolithic device by erasing the ceramic layer of coating.
Before you start dealing with monolithic recovery, we should warn you that the complete process of monolithic device soldering is complicated and requires good soldering skills and special equipment. If you never tried to solder monolithic devices before, it’s better to try your skill on some donor devices where data is not important. For example, you can buy a couple of them just to test your skills of preparing and soldering.
Below you can find the list of necessary equipment:
- A good optic microscope with x2, x4, x8 zoom;
- USB soldering iron with a very thin solder tip;
- Double-sided adhesive tape;
- Liquid active flux;
- Thick jelly BGA flux;
- Hot air gun station (for example – Lukey 702);
- Wooden tooth picks;
- Alcohol (75% isopropil spirit);
- Copper wires with 0.1 mm diameter with a layer of isolation lacquer;
- Jewellery sandpaper (with the size of 1000, 2000 and 2500 (the bigger is the value – the smaller is the sand));
- BGA balls with the size of 0.3 mm;
- Sharp scalpel;
- Pinout scheme;
- PC-3000 Flash Circuit Board adapter;
When all the equipment is ready for soldering, we can start our process.
First of all, we take our monolithic device. In our case, it is small microSD card. We need to fix this card on the table with a double-sided adhesive tape.
After that, we start to erase the layer of ceramic from the bottom side. This operation requires some time, so you should be very patient and careful. If you damage the pinout layer, data recovery will be impossible!
We start with the coarse sandpaper (the largest size of sand) – 1000 or 1200.
When the first largest part of coating is removed, it is necessary to change the sandpaper to the smaller sand size – 2000.
Finally, when the copper layer of contacts becomes visible, we should use the smallest sand size – 2500.
If you perform all the manipulations correctly, finally you will get something like this:
The next step is searching the pinout in our Global Solution Centre.
To continue working with the monolith, we will need to solder 3 groups of contacts:
- Data I/O contacts: D0, D1, D2, D3, D4, D5, D6, D7;
- Command contacts: ALE, RE, R/B, CE, CLE, WE;
- Power supply contacts: VCC, GND.
First, you need to choose the category of your monolithic device (microSD card in our case), and after that you have to choose a compatible pinout (type 2 in our case).
After that, we should fix the microSD card on the Circuit Board adapter for more convenient soldering.
It would be a good idea to print out the pinout scheme of your monolithic device before soldering. You can put the scheme next to you, so that it is at hand when you need to check the pinout array.
We are ready to start the soldering process! 🙂 Make sure there is enough light at your workstation!
Drop some liquid active flux on the microSD pin contacts with the help of a small brush.
With the help of a wet tooth pick we should place all the BGA balls on the copper pin contacts which are marked on the pinout scheme. It’s better to use the BGA balls with the size of ~75% of our contacts diameter. The liquid flux will help us to fix the BGA balls on the microSD card surface.
When all the BGA balls are placed on the pins, we should use a soldering iron for melting tin. Be careful! Perform all the actions gently! For melting, touch the BGA balls with the tip of the soldering iron very quickly.
Using a hot air gun, we should heat our pins with the temperature of +200C. The BGA flux will help to distribute the heat between all the BGA contacts and melt them carefully. After heating, all the contacts and the BGA tin will take a semi-sphere form.
Now we should remove all traces of flux with the help of alcohol. You need to sprinkle it over the microSD card, and clean it with a scrubbing brush.
The next step is to prepare the cooper wires. They should to be of the same length (approximately – 5-7 cm). For cutting the same size wires, we recommend to use a piece of paper as a length gauge.
After that, we should remove the isolation lacquer from the wires with the help of a scalpel. Just scratch them slightly from both sides.
The last stage of wire preparation will be the process of wire tinning in rosin for better soldering.
Now we are ready to start soldering wires to our Circuit Board. We recommend that you start soldering from the side of the Circuit Board and later continue soldering the other side of the wires to the monolithic device with the help of a microscope.
Finally, all the wires are soldered to the Circuit Board, and we are ready to start using a microscope for soldering the wires to the microSD card. This is the most complicated operation and it requires a lot of patience. If you feel that you are tired – take some rest, eat something sweet and drink a cup of coffee (sugar in your blood will help your hands not to shake). After that, get down to soldering. 🙂
For right-handers, we recommend that a soldering iron should be in the right hand, whereas in the left hand we hold tweezers with copper wire.
Your soldering iron should be clean! Don’t forget to clean it from time to time while soldering.
When all the contacts are soldered, make sure that no one of them is connected to the GND layer! All the pins must be fixed very tightly!
Now we are ready to plug our Circuit Board to PC-3000 Flash, and start the reading process! 🙂
Below please watch the full video:
Instead SandPaper you can also use The following tool. It’s a Fiberglass brush which is perfectly clean all compaund and plastic layers, but leave cupper roads in safe!