I'm curious about how ultra compact USB drives, like the SanDisk Ultra Fit, manage to fit their NAND memory inside such a tiny enclosure. Is the NAND actually housed within the area of the USB connector? If anyone has pictures, I would love to see them. Also, what standards or terminology are used for this kind of packaging?
1 Answer
Ultra Fit drives are designed with a tiny PCB that slots right behind the USB-A contacts, all packed into the molded plastic that makes up the plug. Generally, the NAND and the controller are combined into a super compact BGA package, which could either be a stacked multi-chip package or a system-in-package. Sometimes, cheaper versions use a chip-on-board technique where the bare chip is mounted directly on the PCB and coated with epoxy. There isn't really a specific name for the modules, apart from terms like MCP or SiP; it’s all about custom PCBs made to perfectly fit into the USB dimensions. If you're looking for visuals, try searching for "Ultra Fit teardown" or "chip-on-board USB drive" for some neat close-up shots.
You missed mentioning the "flip-chip" technique! It involves solder balls on the Ball Grid Array being directly attached to the board. I remember this technique caused a lot of issues with the original Xbox, leading to massive costs for Microsoft!