Memory Cards in Plain Language.

Types of memory cards — what you actually carry in your camera and phone

All the popular card formats pass through our laboratory. In short:

• SD (Secure Digital) — the "big" card, standard in photo and video cameras. The SDHC and SDXC labels simply describe the capacity range and the file system the card ships with.
• microSD — SD's smaller sibling: phones, drones, dashcams, consoles. It is our most frequent "patient" today — because it is everywhere and because it is the most fragile.
• CF (CompactFlash) — a thicker, sturdier card known from professional DSLRs, with its own pins like a tiny hard drive. Its successors (CFexpress, XQD) work in modern mirrorless cameras.

What a card looks like inside — and why that decides the recovery

From a data recovery standpoint there are two completely different worlds.

"Assembled" cards — some full-size SD and CF cards look inside like a miniature computer: a separate NAND memory chip (that is where your photos live) and a separate controller that manages the writes. When such a card dies, we can take it apart, desolder the memory chip, read it directly in a laboratory reader, and reconstruct the controller's work in software.

Monoliths — practically all microSD cards and more and more SD cards today are a single black "pebble": memory, controller and all connections cast into one block of resin. Nothing can be desoldered. To reach the data, in our laboratory we carefully grind down the resin layer, expose the technical contact pads (different for every manufacturer, often documented nowhere), work out their functions, and connect to them with thin wires under a microscope. The preparation alone can take many hours — which is why recovery from a monolith is harder and more expensive than from an assembled card.

Typical failures we see on the bench

• Logical damage — accidentally deleted photos, a card formatted in the camera, the "card needs to be formatted" message after pulling it out mid-write. The memory is physically fine and the data is usually still there. Good prognosis — as long as nothing was recorded onto the card afterwards.
• NAND wear — every card has a limited number of writes. A dashcam or a CCTV recorder writing in a loop can wear a card out surprisingly fast. Symptoms: the card slows down, files stop saving, and finally the card disappears from the system.
• Mechanical damage — a snapped SD card, broken CF pins, a microSD that went through the washing machine. Everything depends on whether the silicon structure holding the memory was hit, or only the housing and contacts.
• Controller or firmware failure — the card reports as 0 MB, under a strange name, or not at all. The data is physically in the memory; the controller just stopped serving it.
• Counterfeits — a "256 GB" card for suspiciously little money that actually holds a fraction of that capacity with a reprogrammed controller. It records seemingly normally, then starts overwriting older files once the real capacity is exceeded. From such cards we often recover only part of the material — there was physically nowhere for the rest to be saved.

When recovery is possible, and when it is not

Good prognosis: deleted or formatted files (not overwritten), file system errors, a failed controller in an assembled card, a monolith with the memory structure intact.

Hard but doable: monoliths requiring grinding and pinout mapping, heavily worn NAND with many errors (we then read it multiple times and assemble the result from the best reads).

Realistically no chance: a crack running through the silicon memory structure itself, data overwritten by new recordings, and some cards whose controller encrypts the contents with a unique key and is itself beyond saving.

The golden rule: stop using the card

If the data matters — take the card out of the device and do nothing with it. No "test" formatting, no recovery programs "from the internet", no recording more photos. Every write lowers the chances. From experience: most "unrecoverable" cases are cards someone experimented on at length first.

We talked more about how cards fail and how to spot a counterfeit in our interview for blog.cyfrowe.pl (in Polish).

Card failed? See how data recovery in our laboratory works, and check approximate costs in our price list.