Micro SD cards also known as TF or Trans Flash cards are usually found in Smart Phones and tablets as external storage. Used for photgraphs, video, downloads, etc.
There are two problems we find with these devices, Logical and Physical. A logical problem means that the Micro SD Card is still working, but the data on it is not accessible. They are recognised by the camera and the computer as normal but the data is not available.
Physical problems are much more serious. All of the components are integrated into a single device, there are no visible components such as NAND flash memory all that is visible are a few gold plated connectors and the black plastic casing.
Recovery on these has been very difficult and time consuming as first a working unit of the exact same type had to be found and then analysed with expensive test equipment to find out the location of the connection points for the integrated memory. These were then hard wired to an adapter to enable them to be read. The whole process involved and engineer working for several days preparing each memory card and the cost of recovery was very expensive, typically 1000 - 2000 GBP and in many cases way beyond the value of a photos.
Since then we have had special adapters made to enable us to read many of these devices quickly, bring the cost down substantially.