Differences between CS SD NAND and TF Card
As we know, CS SD NAND also called weldable TF card, Mini eMMC, that’s because they have same structures: build-in NAND Flash, controller and firmware.
But they are definitely different in the market position. TF card, as an external storage product, is easy to plug and change. So, for the defective products, the customer just needs to replace them with the suppliers. CS SD NAND is an embedded chip. It is complicated if there are defective products. It’s a very long process from disassembling, refreshing, rewelding to finally return the good products to customer. The long process consumes not only a great mass of time, but also the brand influence. Thus, CS SD NAND require high quality and very lowest defective rate( <=0.2%). But for TF Card, even 1% defective rate can be acceptable.
Requirements for consistency are different for TF card and CS SD NAND. As for TF card, Customers don’t care about what kind of controller and flash used, they only care about the basic transmission protocol. But for CS SD NAND, it usually used to store code or system data, customers are very strict to the product consistency. Any changes in the built-in flash or controller must be notified to the end user, and the sample needs to be re-tested and re-certified. Otherwise, it is easy to cause batch failure.
Generally, TF card focus on cost, always put the quality behind. While SD NAND emphasizes high quality material include flash, chip substrates, bond wires, and molding compound. Take flash for example, CS SD NAND only use original good die, but TF card in small capacity prefer ink die.
When using TF card, there are more problems:
1: the size of TF card is too big
2: Poor contact caused failure access to the data
3: Can’t be welded by SMT machine, low production efficiency
4. Internal data is easily copied
5. Quality for different batches is not consistent for TF card with small capacity
Below table shows very clearly the advantages of CS SD NAND:
For customer who used CS SD NAND at the first time, we provide the matched testing equipment.
