How to determine NAND Flash quality?

Packaging test to form the so-called original Wafer, self-packaged brand, white wafer (Good Die), black wafer (Ink Die), and others on the market.

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NAND Flash manufacturers are mainly Samsung, Toshiba/SanDisk, Micron, and SK Hynix. Wafer produced by the original factory in accordance with the quality difference, packaging test to form the so-called original Wafer, self-packaged brand, white downgrade, black downgrade and other pronouns on the market.
NAND Flash

In simple terms, the original Wafer is the packaging Wafer with the original logo strictly tested by the original factory. The self-packaged brand is the product that obtains the Flash Wafer capacity of the original factory and carries out packaging tests in accordance with its own product standard and the testing standard provided by the original factory. The white Wafer (Good Die) is the Wafer that the original factory sells to the customer, and the customer will package and test the product without a logo. The black Wafer (Ink Die) is the defective product in the Wafer that fails to meet the SPEC standard. Samsung usually kills the Ink Die laser when the Wafer is CP tested. Toshiba, Sandia, SK Hynix, and Micron are using the products and selling them directly to the market. It can be judged that the quality of NAND Flash is original wafer > self-packaged brand > white wafer > black wafer.


Distinguish the original piece, self-packaged brand, original factory quality brand, white piece, and black piece first to understand the chip production process, Wafer is made into the Wafer slice test stage, will be divided into Flash Die qualified and unqualified, and the original factory will test qualified Flash Die packaging, Unqualified Wafer are some leftover materials, which the original factory will scrap, and many of them will flow to the downstream sealing factory in the form of blue film Wafer for processing and recycling, known as black Ink Die, and finally used by some small manufacturers for cheap bundled SD cards and U disk and other products. Due to poor quality and performance, SSDs and EMMCs are not used in most products, but a few manufacturers produce SSDs with black chips and sell them to the market for huge profits.

Qualified Flash Die original packaging factory will be packaged into eMMC, TSOP, BGA, LGA, and other products according to needs, but there are also poor packaging, or performance is not up to standard, these Flash particles will be filtered out again, or flow to the downstream manufacturers, the downstream manufacturers after screening. Flash particles are printed with a non-original logo and sold. In addition, the original factory sells Flash Wafer of consumer-grade to card module factories. These factories don’t have testing technology and directly ask the sealing factory to select Good Die packaging particles according to Mapping.

Good Die, Ink Die, and Self-Packaged flash

Finally, the original packaging and testing qualified Flash particles printed with the original logo or Flash Wafer material sold to the original OEM customers, by the customer packaging into its own brand, this is the best quality, high stability of Flash particles, in the selection of the original logo and original OEM customer self-branded brand logo.

The main logos are Samsung’s OEM customers: Transcend, and FORESEE; Toshiba’S OEM customers: Kingston, Lite ON, and PHISON. Micron’s major OEM customers are Kingston, FORESEE and Transcend. SK Hynix has no OEM customers with the SSD brand. Other OEM customers with a non-original factory strategy buy Flash Wafer to package into their own brand logo, so the quality and supply cannot be guaranteed.


DiskMFR Field Sales Manager - Leo

It’s Leo Zhi. He was born on August 1987. Major in Electronic Engineering & Business English, He is an Enthusiastic professional, a responsible person, and computer hardware & software literate. Proficient in NAND flash products for more than 10 years, critical thinking skills, outstanding leadership, excellent Teamwork, and interpersonal skills.  Understanding customer technical queries and issues, providing initial analysis and solutions. If you have any queries, Please feel free to let me know, Thanks

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