What's in an SD card?
What's actually inside an SD card? I'll bet you've wondered that, but never actually got round to finding out?
I'm sure you've all seen the insides of a USB memory stick - a bunch of chips on a PCB, nothing surprising there. But what about an SD card? Considerably slimmer than a USB key they must be going some to fit the chips you'd expect into it.
Well, since the Raspberry Pi handilly blew up an SD card for me, I thought it was about time to rip one apart and see what it's actually made up of. Well, it contained one or two surprises I must say. Actually one big surprise.
What is inside the SD card? Well, believe it or not, mostly fresh air.
Believe it or not, that's it. A small chunk of solid plastic-like substance (not too sure what exactly it's made of). It's all once piece, and you can just make out the mottled texture of ultra-fine PCB traces in there. I guess those round pads are test pads / programming pads for the internal circuits. It is just one solid lump - no obvious joins or fissures of any kind.
Nothing there at all bar a code number. Just plain matte black.
Looking carefully at an 8GB card you can see the test pads through the plastic. They're further down the body of the card, so the "chip" must be (logically) bigger. I guess that something like a 64GB card might fill the entire body of the SD card - if you're lucky.
So it turns out that the answer to the question "What is in an SD card?" is: "Not a lot."
I have seen pictures of full-size SD card that are a frame containing a mini (or maybe micro) SD card inside. This wasn't an adapter but a sealed card.