Why does an 8 GB and 16 GB USB drive have the same physical size but a different amount of storage? [closed]

In the market, you can get USB drives of different storage sizes. However, among the same brand, I found that those USB drives are physically the same.

How can they achieve this? Is it that different USB storage sizes make use of different file systems?

If they are using the same storage technology, wouldn't their production cost actually be the same for 8 GB and 16 GB USB drives – since they have the same physical size?

Solution 1:

The density of the storage is higher. Put simply there are more NAND flash memory chips (or the chips can hold more). The chips are very small though, so there is some empty room in most USB sticks. Making the chip bigger, or adding a second is almost always possible in the same space.

To save space, NAND flash chips also often package two pieces of silicon to same "chip", meaning the plastic/ceramic piece you usually call "chip" has one, two or four individual pieces of silicon inside. This comes with performance cost, but on USB stocks performance is not usually a concern. This all is made possible by transistors used to implement the memories shrinking all the time.

If you think about microSD cards, they are smaller than nail on my index finger, and they still come with capacities of 16 GB or more. Or SD cards, size of a stamp and 2 mm thin, come in capacities of 128 GB... And one SD card is easily smaller in physical volume than most USB sticks.

It is also a common practice in electronics design to first create the top-end model with all bells and whistles and then just not install some components to get the cheaper models; so these two sticks might very well be all identical, except one of them, while having space for another 8 GB die, does not come with it installed.

The reason for this is that designing the circuit board, testing the design, making molds for plastic parts, etc. is the expensive part. Making a single unit is cheap compared to that. Which means it makes sense to keep the plastic cover and circuit board identical, and just leave out some components, because you then save on the expensive part, materials.

Solution 2:

The size of the USB stick is determined by the marketing people, the design department, and not necessarily the components inside it.

There are USB memory sticks that hold gigabytes of data that fit completely inside the USB port they are plugged into.

For a good example of just how small a thing large amounts of data can fit into, look at Micro-SD cards, which are used in many cell phones. The package is less than a centimeter on a side, only a mm or so thick, and can hold up to 32GB of data.

Generally, higher density components are more expensive. So a normal size USB memory stick doesn't have to use the most expensive, most dense components.

USB sticks are generally designed to fit comfortably within the hand and pocket. Smaller devices are more prone to getting lost, and larger devices won't fit in the pocket quite as well.

So in designing these devices, the company decides on a price point, which will govern to a certain extent how expensive the components can be, the design department decides on a branding and design and size, and then the technical people are told to make it work.