You would never goes just how difficult it was to produce that black bezel, makes you appreciate how hard the white one must have been.
http://cen.acs.org/articles/90/i13/Serious-Surfaces.html
C&EN News Volume 90 Issue 13 | March 26, 2012 | pp. 28-33
Serious Surfaces
Material innovations on the exterior of consumer products bring new functionalities
By Melody M. Bomgardner
A different coating material gives smartphone screens their sleek border of opaque black. In addition to being aesthetically pleasing, the black area hides the underlying electronics and blocks errant light emitted from the screen. To get a rich and opaque black, manufacturers use a thin coating of carbon black, made by companies such as Cabot Corp. But the push for thinner touch screens presents a dilemma for carbon black makers, says Josh Preneta, Cabots global segment manager for coatings.
Standard touch-screen configurations use carbon black printed onto glass, often Gorilla Glass, plus two additional layers of film. The layers are insulated polyester films, each containing a set of nanowires of indium tin oxide (ITO). One layer has wires in the x direction and one in the y direction. However, new, thinner devices call for printing the ITO directly on the cover glass, putting it in contact with the black mask.
If the ITO runs over a surface that is conductive, you get interference, and the touch screen no longer works, Preneta explains. And regular carbon black powder is somewhat conductive. To work around the problem, Cabot needed to develop a resistive carbon black. The coating also needed to be made much thinner to ensure that the touch signal would reach the ITO layer. A standard screen uses a 10-μm layer of carbon black, whereas new touch screens call for a layer only 12 μm thick. To retain the opaqueness we need a higher concentration of carbon black, compounding the possible conductive problems, Preneta says.
Carbon black particles have a morphology that is similar to a cluster of grapes, Preneta says, and modifying that structure contributed to the solution. We can manipulate the number of grapes in each cluster and the size of the grapes, which enables us to make it more conductive or less conductive. In addition, Cabot developed a chemical treatment that eliminates the ability of electrons to jump from one carbon black particle to another. The thinner touch-screen products that recently hit the market feature the modified carbon black.
http://cen.acs.org/articles/90/i13/Serious-Surfaces.html
C&EN News Volume 90 Issue 13 | March 26, 2012 | pp. 28-33
Serious Surfaces
Material innovations on the exterior of consumer products bring new functionalities
By Melody M. Bomgardner
A different coating material gives smartphone screens their sleek border of opaque black. In addition to being aesthetically pleasing, the black area hides the underlying electronics and blocks errant light emitted from the screen. To get a rich and opaque black, manufacturers use a thin coating of carbon black, made by companies such as Cabot Corp. But the push for thinner touch screens presents a dilemma for carbon black makers, says Josh Preneta, Cabots global segment manager for coatings.
Standard touch-screen configurations use carbon black printed onto glass, often Gorilla Glass, plus two additional layers of film. The layers are insulated polyester films, each containing a set of nanowires of indium tin oxide (ITO). One layer has wires in the x direction and one in the y direction. However, new, thinner devices call for printing the ITO directly on the cover glass, putting it in contact with the black mask.
If the ITO runs over a surface that is conductive, you get interference, and the touch screen no longer works, Preneta explains. And regular carbon black powder is somewhat conductive. To work around the problem, Cabot needed to develop a resistive carbon black. The coating also needed to be made much thinner to ensure that the touch signal would reach the ITO layer. A standard screen uses a 10-μm layer of carbon black, whereas new touch screens call for a layer only 12 μm thick. To retain the opaqueness we need a higher concentration of carbon black, compounding the possible conductive problems, Preneta says.
Carbon black particles have a morphology that is similar to a cluster of grapes, Preneta says, and modifying that structure contributed to the solution. We can manipulate the number of grapes in each cluster and the size of the grapes, which enables us to make it more conductive or less conductive. In addition, Cabot developed a chemical treatment that eliminates the ability of electrons to jump from one carbon black particle to another. The thinner touch-screen products that recently hit the market feature the modified carbon black.