NAND Flash Chip Grades Explained

by Nick on September 4th, 2009

Nand Flash Waffer
Today I will touch back on the subject of bad flash drives. You may have heard some people talking about flash chip grades or tier 1/2/3 chips. Formally there are three grades for flash chips A, B, and C and unofficially D. All flash chips start their life on a silicon wafer and are cut from this wafer. Chips that have not passed quality control are pushed aside automatically by the machine cutting the wafer. The different sections of the wafer

Grade A

Also known as tier 1 flash chips are the best chips available. Grade A chips have the manufacturers name and serial number laser etched on the the flash chip. Samsung and Hynix are the largest producers of Grade A flash. These chips will have a consistently low rate of errors, be much faster than other grades, and last you much longer. Vendors offering these chips will more often than not provide a lifetime warranty on the product.

Seeing that these are the chips we use for our wholesale flash drive orders all come with lifetime replacement warranties.

Grade B

These chips are as reliable as Grade A but do not have the etched serial and name from the manufacturer. Both Grade A and B chips are reliable and have low failure rates.

Now to the lower end products. Stores offering these will never provide any type of warranty on their products seeing that failure is guaranteed.

Grade C

Coming back to the silicon wafer there are two parts that are discarded by the original manufacturers. The portions that have not passed QC and the edges of the wafer. Second hand after market vendors will purchase these parts of the wafer from reputable vendors and resell them to end users. These Grade C chips have a 30% – 40% rate of failure. On rare occasion they can cause system instability, depending on the state of the flash and how the computer is reading/writing data.

Grade D

These are hard to find to be honest but if found beware. Some sly vendors have a laser they use to etch things with… anything. These vendors will purchase some Grade C chips and laser etch them with Samsung’s or Hynix’s name and serial number and pass them off as the real deal. Failure rates are the same as Grade C but you will be tricked into paying premium prices for these units. Most of these vendors are located in China.

Buyers Guide (list of helpful tips):

  • Do not choose a foreign vendor who has a price lower than the rest of the market place.
  • Beware all vendors who do not offer you a warranty. If they use Grade A why would they not offer a warranty. If there is no warranty you are most likely being sold cheaper lower grade chips
  • Always inquire about the quality of the products. If a sales rep sounds hesitant it may be best to go with someone else.
  1. George permalink

    Hi Nick,

    Very clear explaination.
    By the way, where I can buy those A or B grade Nand Flash Chip or die?


  2. Nick permalink

    Hello George,

    If you want to purchase the actual raw flash chips you’ll have to make your way over to Taiwan, where there big names in NAND flash manufacture the chips. Apple brokered a few deals with Samsung to purchase something on the order of $500 million worth of NAND flash for their iPhone 3GS and iPhone 4 devices.

    If you want preassembled flash drives you can contact a company like the one I work for, contact info below.

    As for getting your hands on the die or a machine / process to produce NAND Flash silicon wafers you’ll need to put up hundreds of millions in R&D money or buy out a smaller manufacturer. Those big titans have their secret technologies and would presumably do pretty much anything to protect those secrets. So I highly doubt you’ll ever find any equipment for producing the chips floating around say on craigslist or ebay.

    Good Luck and thank you for reading.

    The company I work for is: we are a wholesaler of promotional usb flash drives and other marketing materials. You can reach a sales rep at 1-866-404-4645.


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