Car key fob

Carries and interconnects all electronic components of the key fob

Handles button inputs and communicates with the vehicle via RF

Typical carrier 315 MHz or 433 MHz depending on region

Stores cryptographic data for engine start authorization

Commonly an integrated transponder inside the RF IC package

Radiates and receives the radio signal to and from the vehicle

Printed PCB trace or wire antenna tuned to 315 or 433 MHz

Provides power input to recharge an internal cell or connect a coin cell

Inductive coil for rechargeable designs or spring contacts for coin cell

Supplies electrical power to the key fob electronics

CR2032 3 V coin cell or rechargeable coin cell such as VL2020 3 V

Provide timing reference for the microcontroller and RF subsystem

One low frequency crystal, one RF reference crystal

Detect user presses on lock, unlock and trunk buttons

Surface mount momentary tactile switches

Provides visual feedback during button press or pairing

Surface mount red or green LED

Transfers finger force to switches and seals around button openings

Silicone rubber, 3-button layout

Protects internal components and presents the button faces

ABS or PC-ABS plastic

Completes the enclosure and provides structure for key insert

ABS or PC-ABS plastic

Mechanical key for manual door lock operation

Steel key insert stored inside the fob body

Locks and releases the emergency blade from the fob

Plastic slider with small compression spring

Cosmetic center emblem that covers a recess on the front shell

Plastic or metalized plastic adhesive cap

Reduce dust and moisture ingress at shell seams and buttons

Thin foam or silicone strips

Join the shell halves and secure internal parts

Ultrasonic welds or small screws depending on variant

Channels LED light to a visible window on the shell

Clear molded plastic piece