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Introduction to FLASH chip materials: Differences between original chips and black-and-white chips.
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2014.12.03
The level standards for flash memory are set by flash memory chip manufacturers, and currently, there are no national standards in China.
The best is A+ grade, followed by A grade and B grade. In terms of read/write cycles, speed, power consumption, etc., A+ grade chips of the same specification are superior to A grade chips, and A grade chips are superior to B grade chips.
The industry standard for level evaluation mainly considers the write cycles per cell of flash memory. A grade Flash chips have a usage of 100,000 cycles per storage cell. Additionally, A grade Flash chips have a low bad block rate; in the industry, Flash with a bad block rate below 5% is called A grade Flash, while Flash with a bad block rate above 5% is called B grade Flash.
A wafer contains hundreds or thousands of chips. After the wafer is produced, it must be tested and marked for defects; manufacturers that buy bare chips will cut and bond the uncut wafers themselves, discarding any marked defective chips (die). Another outlet for tested wafers is to be sent for cutting and packaging; after packaging, they become the pin-equipped chips we see. During the packaging phase, any marked defective chips will also be discarded. Typically, the formal testing process is very time-consuming, which increases costs. Some wafer manufacturers sell untested wafers to manufacturers needing bare chips, who then test them themselves. This allows them to purchase cheaper dies, but manufacturers buying untested wafers usually lack good testing equipment and reduce testing items to save money, resulting in some dies that would not pass at semiconductor factories being used in final products, leading to unstable product quality.
In simple terms, the concept of black chips mainly applies to chips, while the concept of white chips applies to both chips and flash memory cards. Black chips refer to defective products selected by chip factories that do not have factory markings or chip model numbers; these chips circulate through various channels into the market. Many large U-disk manufacturers purchase a large number of chips with high bad block rates selected by chip factories and process them technically to create products to lower their costs! White chips are of slightly better quality than black chips and are artificially marked with various labels! However, these are not genuine factory labels! White chips can also refer to white cards, which are flash memory cards with no markings on the surface. Generally, the flash memory industry refers to black chips, white chips, and neutral cards. Black chips mainly refer to Flash chips without any laser engraving on the surface, such as K9K 8G08U0A-PCB0 SLC chips without this model number marked; these are black chips. White chips mainly refer to flash memory cards with no markings on the surface at all, not even indicating what type of card it is. Neutral cards refer to flash memory cards that have markings like Micro SD or SD but do not have a specific brand logo.
Currently, terms like black chip and white chip are popular in the market; they refer to types of Downgrade Flash. Due to advancements in Flash manufacturing processes and capacity increases, the internal composition has become increasingly complex. When new processes are introduced, product yield may not be ideal; some defective Flash may have insufficient capacity, some may not meet lifespan requirements, and some may fail testing. These Flash that do not meet factory requirements are referred to as Downgrade Flash. Some Downgrade Flash is pushed into the market by manufacturers; for example, Spectech is a type of Downgrade Flash from Micron. Another portion is discarded as waste products; however, driven by profit motives, these waste products may also be acquired at low prices and enter the market. Some manufacturers use various scanning tools (Sorting Boards) to identify which can be used. These manufacturers acquire Flash by weight and scan using as few as dozens or as many as thousands of Sorting Boards together daily with a capacity of hundreds of thousands. Most Downgrade Flash is made into SD cards; a small number is used for U-disks, and very few manufacturers use it for producing MP3 players. The handling method for Downgrade Flash is mostly to reduce capacity for sale. Regardless of how it is processed, there are still potential issues. However, due to its low price, the market for Downgrade Flash is continuing to grow.
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