What is the purpose of the dot matrix on BMW rear windows?

[GiselleFitz]

The functions of the dot matrix on BMW rear windows are as follows: For enhanced aesthetics: Since automotive glass and corresponding components are bonded with adhesive, and the glass edges in these areas require adhesive application, the edges are designed in black for visual appeal. These small dots also serve as decorative transitions. Preventing glass breakage: National regulations explicitly prohibit the use of tempered glass for windshields. Modern automotive glass is typically made of laminated glass. While glass itself has excellent light transmission properties and doesn't get extremely hot at the center even under intense sunlight, the metal body frame surrounding the glass reaches much higher temperatures in the sun. This heat naturally transfers to the glass edges, creating temperature differentials across the glass surface. When glass expands unevenly due to heat, it becomes prone to cracking. The dot matrix pattern helps gradually distribute heat absorption, dispersing expansion forces to prevent glass damage. In simple terms, when the window frame gets hot while the glass heats up more slowly, these dots help transition the heat and reduce stress on the window.