DELO: Active Alignment Adhesive

Schematic representation of DELO LED bonding MLA headlamp

Schematic representation of bonding areas for the fixation and alignment of optics in a microlens array headlamp module, adhesive colored magenta for illustration purposes. Image courtesy of DELO.

DELO PHOTOBOND OB4210 is characterized by its yellowing stability at high temperatures and is highly resistant to temperature and media. It can be used by manufacturers of automotive headlights to realize optically sophisticated applications.

DELO reports that the UV-curing adhesive’s transparent characteristics make it hardly distinguishable from the lens material. Its yellowing resistance is higher than similar products, retaining its transparency even after a typical 500-hour storage period at +140 °C, which is important for bonding increasingly powerful LED modules that generate more heat. The acrylic adhesive works with a variety of materials found in a headlight, where it has stress-equalizing effects and a wide elasticity range. Thanks to its near-instantaneous UV curing, it is suitable for high-end applications such as the active alignment of lens systems and optics in matrix LEDs, microlens arrays (MLA), or digital light-processing (DLP) headlamp systems.

In addition to an application temperature range of -40 °C to +140 °C, the adhesive has a high compression shear strength of 35 MPa on polycarbonate, a common optical material in the automotive lighting sector. Its low viscosity of 3,000 mPa-s and subsequent good flowability also facilitates applications on larger surfaces. The exposure time required to cure the adhesive can be reduced to 1.5 seconds at high UV intensities, offering process advantages in the form of higher cycle times in production.

DELO PHOTOBOND OB4210 addresses two challenges for headlight manufacturers — miniaturization and increased functionality — since headlights are becoming increasingly slim while at the same time becoming more powerful in the illumination of the vehicle’s surroundings. Conventional bonding processes within headlights such as screw connections are reaching their limits, and adhesive solutions are increasingly in demand. In order to bond optics and lenses, however, they must meet stringent requirements. They should be stress-compensating and have low-outgassing, withstand high temperatures and various environmental influences, and still remain highly transparent.

Learn more at www.delo-adhesives.com.