Comparison of Advantages and Disadvantages between SD NAND and eMMC
Recently, we have been in contact with some customers who initially planned to use eMMC but felt something was not quite right. After further communication with the customers, we asked them what kind of eMMC they truly wanted. Their answers included: the smallest possible eMMC; the easiest eMMC to solder; the lowest capacity eMMC; the eMMC with the fewest pins; the eMMC with the lowest power consumption; the eMMC with the longest erase-write life; the eMMC using SLC NAND wafers; and the eMMC with the most stable performance.
Based on the customers' requirements, we analyzed the situation and concluded that CS Brand SD NAND is a better fit for these customers. CS Brand SD NAND is a mini eMMC: with a compact size of 6x8mm; the smallest capacity of 128MB, offering a more cost-effective solution; 8 pins, making it easy to solder; built-in SLC NAND wafers with a 100,000 erase-write cycle life; compatible with SDIO, plug-and-play; SD NAND and eMMC have a similar architecture, both featuring built-in NAND Flash wafers, a NAND Flash controller, and firmware.
It can be seen that when customers have the following requirements, SD NAND is a better choice than eMMC:
Small chip size required: The SMD SD card is 6x8mm; eMMC is 11.5x13mm.
Regarding their size and packaging, let me show you a comparison image of the actual products
Small capacity required: SD NAND is available in 128MB-4GB capacities; eMMC typically starts at 16GB.
Long erase-write cycle life and durability required: SD NAND uses built-in SLC NAND Flash wafers, with an erase-write cycle life of 50,000 to 100,000 cycles; eMMC uses MLC wafers, with a cycle life of 3,000 cycles (non-mainstream), and TLC wafers, with a cycle life of around 500 cycles (mainstream).
Easy to solder with fewer pins: SD NAND has an LGA-8 package, making it easy to both surface-mount and manually solder; eMMC uses a 153-ball BGA package, which significantly increases the difficulty of soldering.
The CPU used by the customer does not support the eMMC interface but requires large-capacity storage: This is a common scenario in MCU platforms. In this case, CS Brand SD NAND is the ideal choice.
Low requirements for the number of PCB layers: Many customers work on products like toys, small appliances, etc. A two-layer PCB is usually sufficient. If eMMC is used, the PCB must be at least four layers, which increases the complexity of hardware routing and the cost of the PCB.
So, when is using eMMC more suitable?
When large capacity is required: >= 8GB.
When the main controller supports eMMC.
When the PCB area is large and has more than 4 layers: Using eMMC requires reserving 11.5x13mm of space, at least 4 layers on the PCB, with buried or blind vias; BGA 153-ball package, with a 0.5mm pin pitch.
