OEM: 3M, USA, St. Paul (Minnesota) Year: 2008 Industry sector: diffusor films/light management

Part design:

The new self-luminous license plate (SLN) from diversified technology giant 3M™ makes an instant impression. While standard aluminum license plates are unevenly lit by a small number of lights positioned around them, the new plastic plate is brightly lit from within, making the whole unit highly visible. The light comes from several LEDs which form an integral part of the license plate housing. The plate itself is a laminate made from special optical films. These ensure an even outward distribution of the light from the LEDs. The laminate consists of a special reflective and translucent film from 3M™ and a customized, transparent PC carrier film from our Makrofol®/Bayfol® product range.

Our PC film has several advantages over other materials which were considered for this application. It bonds securely with the reflective outer film from 3M™. It is also highly translucent, exhibits good mechanical strength over a broad range of temperatures, and is resistant to the kinds of chemicals usually found in motor vehicles. A further practical advantage for everyday use is the fact that it can be formed with minimal distortion using the simple, conventional cold-stamping machines found at license plate workshops attached to vehicle registration offices in Germany.

The complete assembly is the result of a close development partnership between 3M™ and Bayer MaterialScience. For example, the license plate housing is made from the PC/ABS blend Bayblend® T 65 and the translucent front of the housing, on which the actual license details appear, from a two-millimeter-thick sheet of the polycarbonate Makrolon®. A special technology is used to give this sheet a matte finish on one side, thus ensuring that the license details are optically isolated from the light distribution system. When it came to developing the laminate, we provided 3M™ with a comprehensive range of services, including screening tests to establish the laminate’s resistance to chemicals.

The 3M™ self-luminous license plate is very flat. The surface of the license plate previously had to be inclined at an angle of 8 degrees to the lighting unit. This complex technical design is no longer necessary, because the backlighting and plate form a single unit. Compared with a conventional plate with exterior lighting elements, this not only allows more freedom in customizing rear-end designs, but also creates more space in the trunk area – an additional depth of up to seven centimeters. Safety is also improved. The fact that the license plate is much more visible helps avoid rear-end collisions.