My digital camera (a Sony α55) stores photos on an SD card. When I want to transfer these to my computer (a mid-2010 MacBook Pro), I have two options: use the USB cable to connect the camera to the computer, or use the computer's built-in SD card reader.

The camera's SD card slot is the standard click-in, click-out (spring-loaded) mechanism. My laptop has a simple slot into which the card slides with a little more resistance than the former (the card slides only about halfway in so it can be easily removed).

I notice that the card's contacts now have some shiny marks from one or both of these card slots:

Does this type of wear threaten to significantly damage the card? Should I avoid switching the card between slots frequently, to extend its lifetime?

  • 1
    In my experience, the plastic parts of a frequently-used SD card (or even not-so-frequently-used, in the case of some cheap brands) are more likely to fall apart before the contacts wear out.
    – user55325
    Mar 29 '12 at 2:27
  • You can slightly extend the life of the contacts (and the sockets) by wiping the contacts clean and then applying a very thin coating of silicone grease. (And, no, the grease will not "insulate" the contact, and you do not want or need conducting grease.) Mar 29 '12 at 11:07

Here is example of SD card specification: http://www.transcend-info.com/products/spec.asp?Stype=Spec&ModNo=376&flag=showdetail

Durability 10,000 insertion/removal cycles 7 years while you'll use it every day ( remove from camera, plug in to computer, remove from computer and plug in to camera ).

And remember, you can buy another card, but you can't buy(and easily change) USB plug in camera. USB plug is not very durable too.

  • 3
    too true, break the USB input , and it is not as easy to fix as getting a new card. I have cards that look worse than/have more wear than that, I just clean it with alcohol and Q-tip. just have a backup.
    – Psycogeek
    Mar 29 '12 at 3:41

The dark marks you see there are not actually scratches, but rather accreted dirt. You can usually wipe off the dirt and other patinas that tend to accumulate on metal with a soft, rubber pencil eraser. The contacts will be nice and shiny again and have electrical conductance that’s about as good as new.

The lighter marks you see on a couple of those contacts are indeed scratches. That is a little unusual because the pins in the reader are usually curved and don’t generally lead to that much scratching. There’s a few options:

  1. Insert the card more gently, and straight in, not at an angle (always a good idea anyway)
  2. Use a different reader if possible
  3. Replace the card if possible
  4. Alternate two or three cards to spread the wear out
  5. Use the cable to connect the camera to transfer the photos (page 165 of the manual) instead of physically moving the card (Mac-specific on page 166); set the mode USB connection mode—page 54—to Mass Storage so that it appears as a drive
  6. Use a wireless Eye-Fi card instead of an SD card (page 147)

In general, if you are making that much use of a card, the NAND cells will probably wear out before the contacts do (in fact, the pins on the reader will probably bend or wear out before the pads on the card will).


Yes contacts wearing out can cause card failure, found in this document.

One can assume frequent removal and insertion will accelerate when the failure will occur, some things we don't know is how thick the gold on the contacts is, and the alloys use in the gold, which would determine how quickly it will fail in your particular case.

enter image description here

Click "Articles" on the right side of this page for more technical documents on gold contacts.

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