Lighting unit for vehicles and mounting method

1. A lighting unit for vehicles, comprising:

a light source arranged on a circuit board;

an optical attachment mounted in a direction of light emission in front of the light source, said optical attachment comprising at least one holding turret on a first side facing the circuit board such that, at its mounting position, the holding turret slots into a hole drilled into the circuit board;

wherein the optical attachment is positive-locking to a holding body arranged on a second side facing away from the light source; the holding body is molded to a carrier frame; at least one of the holding body or the carrier frame being configured to snap on to the optical attachment; and

multiple spring elements, on at least one of a top side or an underside of the carrier frame, extending in the direction of light emission such that every spring element rests behind a latching hook molded to the optical attachment.

2. The lighting unit of claim 1 , further comprising a cuboid heat sink located between the holding body and the circuit board, the cuboid heat sink being snapped on to the holding body.

3. The lighting unit of claim 1 , further comprising a heat sink having a recess in a side wall and a locating element configured such that at a mounting position, the locating element of the holding body snaps into an inside of said holding body.

4. The lighting unit of claim 1 , further comprising the holding body having a spring clip, said spring clip, at a mounting position, pushing against a bottom wall perpendicular to a side wall of a heat sink.

5. The lighting unit of claim 1 , further comprising a locating element of the holding body and a recess in a side wall of a heat sink are each arranged on sides opposite to a mid plane of one of the holding body or the heat sink.

6. The lighting unit of claim 1 , further comprising the optical attachment comprises at least two holding turrets of different lengths; the longer one of the holding turrets has a chamfered insertion end.

7. The lighting unit of claim 6 , further comprising the holding turrets being geometrically shaped such that the shorter of the two holding turrets automatically slots into a hole drilled into the circuit board as the optical attachment moves towards the circuit board in the mounting process.

8. The lighting unit of claim 1 , further comprising the circuit board being a flexible circuit board whose flexible covering layer has a tang protruding from an edge of the drill hole such that said tang, when a holding turret slots into the drill hole, engages a gap between the edge of the drill hole and the holding turret in order to preliminarily clamp the optical attachment to the circuit board.

9. A method of mounting a lighting unit such that an optical attachment is joined to a circuit board populated with multiple light sources and also joined to a holding body, said method comprising:

putting the optical attachment in place on the circuit board such that a first assembly unit is made by a holding turret of the optical attachment slotting into a hole drilled into the circuit board,

making a second assembly unit by locking a heat sink with the holding body molded to a carrier frame,

locking the first assembly unit and the second assembly unit together, and

extending multiple spring elements on at least one of a top side or an under of the carrier frame in the direction of light emission such that every spring element rests behind a latching hook molded to the optical attachment.