The easiest way to make sure data on an old SSD is no longer accessible, is by encrypting all data, according to cloud storage service BackBlaze. Users who want to recycle or get rid of their SSD should encrypt the data and throw away the encryption key if they want to make sure nobody can gain access to current or even deleted data.
Data on traditional hard disk drives can be made inaccessible by physically damaging the disk e.g. with a hammer, or by degaussing the disk with a strong magnet. But because a SSD consists of many small memory chips it’s hard to guarantee no data remains accessible when physically damaging a SSD. Also degaussing doesn’t work for SSDs as they don’t work with magnetism.
Another method used for HDDs is overwriting all data with zeros but also this doesn’t work with SSDs.
Therefore BackBlaze recommends to encrypt all data and then throw away the encryption key. “Without having the passphrase or encryption key to recover from, any data on that drive is useless to anyone that finds it,” the company writes on its blog.
Users that want to be even more sure the data is inaccessible are advices to format the encrypted drive, and then to encrypt and format again.
Backblaze also mentions there is another even more safe method, shredding the SSD physically. However for most home users this is not an option, devices that can shred a SSD into small particles costs thousands of dollars. (See video below to see how a SSD ends up in thousands of pieces using such a machine that can handle both SSDs and HDDs)