The Bill-Of-Material (BOM) for a product is list of all the components and pieces that are needed to build that product. The importance of understanding the BOM is to understand what makes up the part you are buying.
For flash storage devices, the BOM includes the list of the controller, flash and other components. It also includes the Printed Circuit Board (PCB), discrete components, connectors and lid set.
A key item that is often overlooked is the firmware which runs the controller. Many manufacturers revise firmware regularly without notice to use the lowest cost memory or to tweak some other aspect of the product.
Changing firmware can be good if it is fixing a catastrophic bug, but it also introduces the opportunity for additional bugs to creep into the system. Without a thorough qualification of each new BOM, there is no way to prevent newly released bugs or compatibility issues from entering the field.
Consumer customers are generally not aware of a firmware level or even the controller and memory used inside their flash cards. This is understandable since consumers are generally looking for a part in a simple application like a digital camera or mobile phone. If the part doesn’t work, they bring it back to the retail location for a new one.
In the case of OEM companies, many OEMs know they’re receiving Industrial Grade products because they’re based on SLC NAND. But, they may not be aware the firmware, controller and manufacturer/generation of NAND flash which is being supplied inside the cards.
This is a big deal because the flash cards in these systems make their way out into the field in a large number of devices. Once in the field a failure or corrupt data can be expensive to remedy - if at all.
True BOM Control means locking the controller, firmware, memory manufacturer and specific generation of NAND. It means controlling what is shipped to the OEM customer so they KNOW they’re getting the same product they originally qualified.