From Repair Mobile

Installation of a Nokia 3285/ 5110/ 5120/ 5125/ 5160/ 5165/ 5170/ 5180/ 5185/ 5190/ 6110/ 6120/ 6160/ 6160i/ 6161/ 6162/ 6168/ 6170/ 6180/ 6185/ 6190/ 7160/ 7190 antenna

1. Important: These instructions are to guide you through the process and are to be used at your own risk. Do not poke at the circuit board! Do not have any other power source attached! A T-6 Torx Screwdriver bit will fit those tiny screws on the back of the cell phone to permit removal of the circuit board...
2. Remove battery.
3. Remove the 4 screws with the Torx T-6 screwdriver.
4. Turn the cellular phone so that the face is down. This ensures that the earpiece will not fall out of position! More details [1] - thanks to aftermarketcellular.com