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Optical Bonding on Curved Substrate Disclosure Number: IPCOM000247372D
Publication Date: 2016-Aug-29
Document File: 2 page(s) / 354K

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In this paper we propose a method of patterning Optically Clear Adhesives layer to maintain adhesive material properties while providing better lamination capability for curved display surfaces. Patterned surface OCA has demonstrated the capability to provide air bleed function during the lamination. In this way, we have shown capability to meet both requirements of low tack during processing steps and high surface adhesion in finished article. Low tack during processing steps is required in order to avoid precontact and high surface adhesion in the finished article is required to avoid delamination in the curved region. As an example of a patterned adhesive surface, 3M Company already provides this technology as commercial products that it sells into commercial graphic application. Major advantage for this technology is to make very good lamination quality with an adhesive having some micro channels or other surface structures that can act as the air bleed passages to remove minimize air bubbles during lamination.

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Optical Bonding on Curved Substrate

 As a one of smartphone design trend, some brand new smartphones with curved display has been launched in the market recently. Curved display generally uses optically clear adhesive (OCA), transparent adhesive, to bond bent cover glass or plastic with flexible material such as flexible display and flexible touch module. To date, bent display has a smooth bending radius approximate 10mm radius to 5mm. Recently some smartphone manufacturer begin to make a bent display having lower bent radius, under 5mm. However, it is not easy to laminate thin and soft adhesive with flexible components especially when bent radius is less than 5mm. Stiff bending radius brings bubble or unevenness on bent cover window area if general OCA used in under 5mm radius. So, it would be needed new type of OCA to solve uneven lamination issues for bent substrate. Generally, OCA is required to have high tack and initial adhesion on substrate. Normally, OCAs can meet these performance requirements for planar application. In case of bent substrate, however, especially for bending radius below 5mm, the OCA layer needs to have lower tack and high cohesion during lamination on the curved substrate. The easiest way to accommodate this is to choose adhesive materials that are both less pliable having lower tack. The disadvantage of this material change is that general results that as adhesive materials become less pliable - stiffer-they typically loose both tack and flowability as well.

  In this paper we propose another way to get better lamination capability by patterning the OCA. Patterned surface OCA has demonstr...