What's in an SD card?

sd1What'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.

This is all there is:

sd3

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.

The other side is just as innocuous:

sd2

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."


Posted: 4 years 9 months ago by Jon Chandler #12970
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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.
Posted: 4 years 9 months ago by majenko #12971
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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.
Wow. Economies of scale I guess. Make 1,000,000,000,000 micro SD cards, and stick some in sealed "adaptors" - could be cheaper than making 500,000,000,000 of one and 500,000,000,000 of the other I guess...
Posted: 4 years 9 months ago by Jon Chandler #12968
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Yep...or your order for micro cards got canceled......

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