Key assembly for electronic device

A key assembly (200, 300) for an electronic device (100) that includes a keycap defining a key that has a non-opaque portion to identify the key that is backlit. The assembly includes a light guide (204) positioned in spaced relation to the keycap. An optical radiation source (202), such as top-fire light emitting diode, is mounted below the lower surface of the light guide (204). A mask (250) is disposed on the top surface (218) of the optical radiation source (202). The mask (250) includes an aperture (252) to allow light from the optical radiation source (202) to pass into the light guide (204), and the mask (250) blocks at least a portion of the light from the optical radiation source (202). The mask (250) blocks a portion of the top surface (218) of the optical radiation source that emits tinted light (212, 214). The light guide (204) is affixed atop the opaque mask (250) such that it is nearly directly affixed to the optical radiation source (202).