Why do the USB-A Expansion Cards have a metal sliding cover whereas USB-C cards are plastic?

I opened a USB-C Expansion Card to look at the circuitry inside it (picture, for those curious).


I also wanted to take apart the USB-A card, and I noticed that the USB-A cards have a metal sliding cover / back plate, unlike the USB-C cards, which have a plastic one.

Unlike the USB-C Expansion Card, I wasn’t able to open the USB-A cards (following this guide).

That got me thinking about why it could be metal. The first thing that came to mind was that it had to be conductive and that some wire on the inside is soldered to it, and that could also have been the reason that I couldn’t get it open. However, nothing conductive in the Framework Laptop seems to make definite contact with the metal plate. The metal plate does make some contact with the outer metal housing, and the outer metal housing might make contact with the metal body of the laptop, but the contact isn’t amazing so I highly doubt it’s designed for this.

Does anyone have a clue?

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Perhaps the thickness of the internal components of the USB-A device need a little more space than the USB-C pass-through.

The metal cover is likely thinner than the plastic cover.

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That’s a very good point. I was able to slide the metal cover of the USB-A card back a little, like a millimeter or two, and it looked like components were right up against it, or at least almost, unlike with the USB-C card where there was a lot more room.

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The USB-C is a pass-through, with minimal circuitry. The USB-A probably has components to do signal conversion of some sort.

Some one posted on this site a very detailed explanation of USB and Thunderbolt standards. Perhaps that post can help answer some questions.

I can’t find the post, but I do remember there was a post from the devs saying it was because of the size of the USB-A socket meant that the expansion card cover had to be super thin, too thin for plastic

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I actually almost broke my USB-A Card trying to open it lol. I thought it was just because my palms were sweaty, but it’s great to see that this isn’t just me.

I didn’t break mine, luckily I gave up before that. Thanks for the heads up, I’ll be sure to never try this in the future. :slight_smile:

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@nrp answered the same question last year here:

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Ah, good to know. I guess this being a duplicate is a good thing for now, because I wasn’t able to find the other post using the search keywords I tried before making the topic :slight_smile:

(Relevant thread about how some duplicate content can be good on Discourse, from the creator of Discourse) Can I add hidden metadata like word synonyms to topics to make them easier to find? - #4 by codinghorror - feature - Discourse Meta

In case you’re still trying to get the card open, I made a little video showing that you do open it the same way as the 1tb card. It takes a little force, and pressing down on the metal can help.

Imgur: The magic of the Internet (turns out its a strain to get a good file for the forum, I could not get a small enough gif of this for the life of me)

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