In the fiercely competitive global display market, Chinese manufacturer Continuously drive technological innovation and cost optimization. In response to customers’ customized requirements, LCD Module manufacturers often employ two key process‑streamlining strategies: TFT The number of photomasks has been reduced from five to four, and the OC (Over Coat) filler layer has been eliminated in CF glass. These measures have significantly cut mask costs and boosted production efficiency, but they also place stringent demands on the process capabilities of the production line—particularly for lines with aging equipment, where even a minor oversight could trigger widespread quality issues.

The Double-Edged Sword of Process Simplification: Technical Analysis and Risk Management

I. Risks and Countermeasures Associated with Removing the OC Layer from CF Glass
In the precision structure of CF glass (substrate → BM layer → RGB layer → OC layer → ITO layer), the OC layer plays a crucial role:

Smoothing effect : Fill the height differences between RGB three-color pixels

Protective effect : Prevents damage to the RGB layer and ensures surface flatness.

Canceling the OC layer will directly result in ：

Surface roughness of the ITO electrode → Disordered alignment of liquid crystal molecules

Frequent display defects: star‑like bright spots, motion blur, and afterimages (localized LCD response lag).

Strategies of Chinese Display Manufacturers ：

Increase the shading area of the BM. : Compensates for light leakage caused by height differences

Strictly control the RGB step‑difference process. : Reduce pixel height fluctuations to the nanometer scale

Drive Scheme Optimization : Uses dot inversion driving to reduce crosstalk (at the cost of higher power consumption and greater complexity)

II. Challenges and Breakthroughs in the TFT Glass 4-Mask Process
The conventional five‑mask TFT process comprises: the gate layer, the gate insulator layer, the source/drain channel layer, the via layer, and the ITO layer. The key to reducing this to four masks lies in combining the patterning of the gate insulator and the source/drain layers into a single photolithography step, enabling multi‑region exposure with a single mask.

Process reduction triggers a chain reaction. (According to research by Ye Ning of CETC Panda):

The step height has increased. : An a-Si/n+a-Si layer has been added beneath the SD layer, resulting in a step height of 0.26 μm → compressing the internal space of the liquid crystal cell.

Cell gap increased by 0.03 μm. : The SD film layer’s taper angle increases by 8.99° → the relative height of the liquid crystal rises

Gravity Mura Risk : Within the high-temperature boundary, a 1% reduction in LC margin may lead to uneven display.

Key Control Points in Process Control for Chinese Manufacturers ：

Precision Etching Management : Prevent residues from causing short circuits in GOA circuits (the risk is irreversible)

Dynamic Box Thickness Correction : Adjust the CF PS (Photo Spacer) height according to changes in Array film thickness.

Enhance Insulation Protection : Prevent breakdown of the insulation layer between the GOA wiring and the gold ball (Au Ball) due to external pressure or prolonged illumination.
 

Chinese Wisdom: The Art of Balancing Cost and Quality

Leading Chinese display manufacturer A systematic solution has been established:
▶ Digital simulation takes precedence. : Use modeling to predict the impact of step differences on the electric field within the enclosure and optimize the design.
▶ Strengthening Online Monitoring : Introduce AI-powered visual inspection for Mura defects and micro‑short circuits to detect anomalies at an early stage.
▶ Driver IC Co-Optimization : Customizable point-flip waveform compensation response delay

Conclusion: Building a Robust Manufacturing Moat Through Technological Depth

TFT The decapping and CF de-OC processes are like a delicate surgical procedure, putting one’s skills to the test. Chinese LCD manufacturer The deep technical foundation underpinning this progress. From meticulous control of material properties to the elimination of nanoscale step differences, from optimizing etching parameters to pioneering innovative drive algorithms, every step embodies our commitment to “reducing costs without compromising quality.” As the precision of domestically produced high-generation production lines continues to improve, China’s smart manufacturing is transforming the “impossible triangle” of cost, efficiency, and quality into a core competitive advantage, injecting fresh momentum into the global display industry.

About CNK

CNK Electronics, founded in Shenzhen in 2010 and expanding its investment in Wuping, Fujian, in 2019, is a specialized, refined, distinctive, and innovative enterprise integrating the design, development, manufacturing, and sales of display devices. The company is committed to seamlessly blending smart technology with display innovation, offering customers worldwide a comprehensive portfolio of high‑quality, cost‑effective small- and medium‑size displays, along with tailored solutions and services. Guided by technological advancement and underpinned by uncompromising quality, CNK adheres to the principles of sustainable development, striving to become a leading innovator in the display industry and delivering superior, reliable, and responsive service to its clients.