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2019

06/10

Why do solid-state drives use NAND Flash as storage medium? How to distinguish the quality?

Solid state drives, SSD, full name solid state drives, using flash particle NAND Flash as storage medium, is the most important component of solid state hard disk, solid state hard disk is one of the most important hardware in our computer, so how much do you know about it?


Why NAND Flash is chosen as storage medium for solid disk?


Firstly, it has excellent read-write performance, large storage capacity and cost-effective ratio, so it is more suitable for the large capacity demand of solid-state hard disk. This is also the difference between Nor Flash and it, so it can become the storage medium of solid-state hard disk.


How does NAND Flash work?


NAND Flash does not support data coverage, so it is necessary to write data in blank cells. Usually it is written in pages and erased in blocks. Before erasing blocks, it is necessary to remove the valid pages. Each block has erasure limit (i.e. service life), so the quality of NAND Flash is very important at this time.


However, the general consumers do not have the knowledge and external conditions to recognize the quality of NAND Flash, so hard disk failure and data loss often occur.


What is the quality of NAND Flash?

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Wafers are made of pure silicon (Si). Wafers (like every small square in the picture, also known as die) are produced on the basis of wafers, which can be encapsulated into flash particles after re-processing.


In the production of flash memory particles, it will be tested on the wafer. After passing the test, it will be cut and encapsulated. After encapsulation, it will be tested again. The first time it is eliminated is black, the second is white, and the whole pass is the original. The original will be used as the original solid-state hard disk, or sold. The original will generally have a clear manufacturer logo and specifications code.


Due to failing the original standard test, white wafers are generally purchased as degraded wafers by downstream second-tier manufacturers, and the quality of products such as solid-state hard disk or U disk will not be much different from that of original wafers; there is also a kind of defective particles that fail even the industry standard test, called black wafers, because wafers flow into downstream manufacturers in the form of whole wafers, so some bad manufacturers will beat them. After grinding, print the logo of the original factory and sell it again, so as to gain the low price advantage and carry out malicious market competition, but the service life can not be guaranteed, so as to deceive consumers.


What should ordinary consumers do?


In addition to senior players, ordinary consumers are not good at NAND flash, so this gives bad business opportunities, then how should we resist this behavior as ordinary consumers? In fact, it is very simple, flash particle manufacturers are mainly represented by Samsung, Meguiar and other major manufacturers, small white users do not want to waste time, just in the formal channels, to buy. Big brands will do.