Mechanical Configurations

There are a variety of product configurations that can be used for optically bonding electronic displays including:

  • Over-frame bonding – uses the original metal frame of the LCD for mechanical support. A sealant is used to prevent ingress of the bonding adhesives into the display electronics. The cover glass rests over the frame of the LCD and is optically bonded to the front surface of the LCD and sealed on the perimeter.
  • Under-frame bonding – the metal frame of the LCD is removed and the cover glass is sealed to the front surface of the LCD. The frame may be replaced after the bonding process or the bonded display may be integrated into a custom bezel or enclosure.
  • In-frame bonding – the metal frame of the LCD is left in place and the cover glass is bonded within the viewing area of the display.
  • Rear-surface bonding – the LCD is disassembled and an optical filter (e.g., transparent heater) is optically bonded to the rear surface of the display. This design is used for low temperature operation and, in some cases, to improve the ruggedness and mechanical strength of the display.

IMO-bond™ display configuration matrixIn general, over-frame bonding is most commonly used, especially with touch screens and digitizers. It is also the least invasive optical bonding process and, because the display’s frame provides additional mechanical support of the cover glass, there is less chance of “glow marks” or “picture framing” on the display due to stress that can be induced by the bonding process.

Filter Type
Bonding Type Cover Glass EMI/RFI Heat Shield™ Therma Klear™ NVIS-Compatible
Over-frame Yes Yes Yes Yes Yes
Under-frame Yes Yes Yes Yes Yes
In-frame Yes Yes Yes Yes Yes
Rear-surface N/A N/A N/A Yes At light source or full surface


Utilizing Dontech’s multiple Class 1000 clean rooms, the IMO-bond™ process is applicable to displays of nearly any size and customized for low volume prototyping to high-volume production (>5000 units). Dontech display engineers are available to discuss your project details.