With the large-scale promotion of high-definition displays such as ultra-thin and ultra-narrow bezels, the full lamination process has become the best lamination solution for high-end mobile phones and tablets. In the full lamination technology, according to the different positions of the touch lines in the overall stack structure, they can be divided into GFF, OGS, On-cell, and In-cell.
GFF
Make the touch sensor on the transparent substrate, and then stick it on the CG (cover glass). The full lamination process changes the touch layer of the glass substrate in the middle of the non-full lamination process to a film substrate, and then coats a conductive coating (IOT Film, indium tin oxide film) on the upper and lower sides of the film substrate to reduce the thickness.
Process flow:
1. Large glass–>cutting–>film on both sides –> strong acid etched edge sawtooth –> chemical strengthening–>cover glass
2. Flim yellow light process/laser (making touch circuit on PET material) –> film sensor
3. Cover glass + glue + film sensor –> OCA Paste (optical glue) –> paste LCM –> complete
OGS
The OGS process directly applies the touch sensor to the cover glass, with a thin overall thickness, high touch sensitivity and good optical effect. However, since a large piece of glass needs to be cut after making the touch circuit in the process, the cutting process will generate many serrated edges and corners, and the product may have edge cracking problem, so the strength is low.
Process flow:
1. Large piece of glass–>chemical strengthening (to make the glass structure full)–>yellow light process (making touch circuit)–>cutting–>film on both sides–>strong acid etching edge sawtooth–>chemical strengthening- ->OCA Paste–>Paste LCM
On-cell
The touch sensor is embedded between the polarizer and filter of the display.
In-cell
The touch sensor is embedded in the liquid crystal display layer of the display screen.
Process similarities and differences
In fact, GFF full lamination is not a real full lamination technology. The real full lamination technology is to fuse the touch layer of the middle layer up or down, while GFF uses optical glue to attach the ITO Film touch layer upward. , which is more advanced than non-full fit, but it is not strictly a “fusion”. The real full lamination technology, such as OGS touch unit upward and protective layer fusion; such as On-cell, In-cell touch unit downward and LCM fusion. Based on process integration, touch panel manufacturers mainly promote GFF and OGS technologies; while display panel manufacturers mainly promote On-cell and In-cell technologies.
At present, many third-party iPhone screens use the in-cell touch, and a few use on-cell or OGS. If compared in terms of touch sensitivity, color display effect, and screen durability, in-cell is the best. If you want to know more about the difference between on-cell touch vs in-cell touch, I suggest you check out this article by taoyuanparts –> iPhone Screen Structure: Difference Between In-cell, Out-cell and On-cell.