The fundamental difference between storage modules and embedded chips

  Since Leilong has been continuously selling CS Genesis SD NAND (also known as mini eMMC, small-size/small-capacity eMMC, soldered T-card, soldered TF card, and soldered SD card), users often ask: What are the differences between SD NAND and TF cards?

Previously, we wrote an article to explain this: https://www.longsto.com/news/327-en.html

  Here, we would like to analyze the differences from the perspective of an external module (such as a TF card) versus an embedded chip (such as SD NAND or eMMC, which can be soldered onto a PCB).

Take a moment to look around—have you noticed that there are many manufacturers producing TF cards? From major brands in the US, Japan, and South Korea to numerous white-label TF card manufacturers around Shenzhen, the market is vast. However, when it comes to embedded eMMC or eMMC brand manufacturers, the number is significantly smaller. Why is that?

From a basic chip architecture standpoint, TF cards, SD NAND, and eMMC all consist of an internal NAND Flash wafer, a NAND Flash controller, and firmware.

However, there is a fundamental difference in their original product positioning.

Storage modules (such as TF cards) are designed as external storage solutions, allowing for easy insertion and removal at any time. They can be replaced freely without requiring high-temperature reflow soldering.

In contrast, embedded chips are intended for internal storage, meaning they are soldered directly onto the PCB. Replacing them is highly inconvenient, requiring product disassembly and specialized tools. Additionally, embedded chips must withstand temperatures of approximately 250°C, as they undergo high-temperature reflow soldering during PCB assembly.

What Differences Arise from These Positioning Variations?

1. Different Defect Rate Requirements

External storage products (such as TF cards) can be easily replaced if defective—users simply send the faulty card back to the manufacturer for a new one.

However, if an embedded chip like SD NAND fails, the entire customer product must be returned to the factory for rework. This involves disassembly, board removal, cleaning, re-soldering, and then shipping the repaired product back to the end user. The process is time-consuming, labor-intensive, and significantly impacts user experience and brand reputation. Even a small defect rate can have disastrous consequences.

As a result, the defect tolerance for external storage modules and embedded chips differs drastically. In the TF card market, it is common for suppliers to factor in a 1% defect rate into the pricing, sometimes even offering no warranty. In contrast, such a model is entirely unacceptable for embedded chips, where near-perfect reliability is essential.

2. Different Consistency Requirements

For TF cards and other storage modules, as long as they meet basic data transfer protocols, the internal controller and Flash configuration do not need to be strictly controlled. Manufacturers have flexibility in component selection without notifying users.

In contrast, embedded chips such as SD NAND and eMMC often store system code or critical data, making product consistency a top priority. Any changes to the internal wafer or controller must be formally communicated to end users, requiring re-sampling, testing, and certification. Failure to maintain consistency can lead to catastrophic issues, such as widespread device failures (e.g., mass smartphone “bricking”).

3. Different Material Quality and Cost Priorities

Due to intense competition and relatively lower quality requirements, TF cards and other external storage products prioritize cost-effectiveness in material selection.

On the other hand, embedded chips such as SD NAND and eMMC prioritize high-quality materials. This includes the internal NAND Flash wafer, chip substrate, bonding wires, epoxy encapsulation, and more—these components are typically of a different grade compared to those used in TF cards.

4. Different Packaging and Testing Process Requirements

Manufacturing embedded chips like SD NAND and eMMC demands stringent control over key production processes such as wire bonding, molding, baking, and dicing. Poor management of these steps can lead to batch-level defects, which are unacceptable in embedded applications.

Now, you can see why there are so many manufacturers producing TF cards, while the number of companies making SD NAND and eMMC is significantly smaller.

Currently, external storage module products in the market include TF cards, SSDs, and USB flash drives, while embedded chips include SD NAND, eMMC, and eMCP. If you compare the number of manufacturers in each category, you’ll notice a clear pattern.

Many customers tend to think of CS Genesis SD NAND as a soldered version of a TF card. However, a more accurate comparison would be a miniaturized eMMC. Compared to eMMC, CS Genesis SD NAND is smaller in size, has fewer pins, lower capacity, easier solderability, and better compatibility.

If you have any questions, please contact us

Email：line@longsto.com