Most processors are encapsulated into a plastic package with a heat spreader today.
Typically, a die is encapsulated into a ceramic or plastic package to prevent damage. Modern processors also carry a so-called heat spreader, which offers protection as well as a larger contact surface for your processor cooler.
Test & Burn-In
The last step comprises another testing and burn-in process, which is performed at increased temperatures according to the processor specification. A material handling solution picks the processors up and positions them, so it interfaces with a test socket. The testing equipment then performs an analysis of all the functions.