It all depends on how "dead" it is.
iPhone data recovery depends on minimum a few things which MUST work together:
* Flash storage chips, for obvious reasons.
* CPU, which holds part of the flash storage decryption keys.
* Working screen input, so you can enter the passcode, which is the other part of the decryption keys.
With those salvageable, you figure out how to make it power on and have a way to export the data, wifi or USB.