In the production process of display panels such as LCD screens, touch screens, and OLEDs, the bonding process is a key factor in determining product quality. Whether it is the bonding between polarizing film and liquid crystal glass substrate, or the bonding between touch screen glass and glass, or the bonding between glass and OCA optical adhesive, if there are residual bubbles between the bonding layers, light spots or dark spots may appear, and severe cases may cause the entire panel to be scrapped. To address the pain points in this industry, high-pressure defoamers are essential core equipment. This article will discuss in detail the role it plays in the manufacturing of display panels.
1、 What is a high-pressure defoamer
High pressure defoamer is a specialized equipment that uses high temperature and high pressure environment to eliminate internal bubbles in bonded products. It injects pressure medium into the sealed chamber and cooperates with a temperature control system to compress, dissolve or discharge the residual air between the bonding layers, thereby making the adhesive layer tightly adhere to the substrate. Taking the high-pressure defoamer produced by PowerDe Automation Precision Equipment Co., Ltd. as an example, its tank body is made of SUS304 stainless steel material, with a diameter of 1000mm and a length of 1200mm. It meets the safety level of a Level 2 pressure vessel standard, with a pressure range of 0.1~0.7MPa and a test pressure of up to 1MPa. The pressure display adopts a digital display, and the unit can be freely switched between MPa, kgf/cm2, bar, and psi, which can meet the strict requirements of the display panel production line.
2、 Working principle of high-pressure defoamer
To understand the function of a high-pressure defoamer, one must first understand its working principle. The entire defoaming process can be roughly divided into four stages:
1. Feeding and sealing stage. Place the assembled panel components into a sealed chamber and seal them using mechanical or hydraulic structures to ensure stable high-pressure environments in the future.
2. Vacuum pretreatment stage. Some models integrate a vacuum system, and the chamber is first evacuated to a low vacuum state. The vacuum environment will reduce the pressure difference inside and outside the bubbles, allowing the small bubbles between the bonding layers to gradually expand and aggregate into larger bubbles, creating conditions for subsequent high-pressure compression. This step is particularly important for high viscosity adhesive materials.
3. High pressure compression stage. This is the core process of defoaming. The device injects pressure medium into the cavity to raise the internal pressure to the set value. According to Boyle's law, the pressure of gas at a constant temperature is inversely proportional to its volume. High pressure will forcibly compress the volume of bubbles, and after the bubbles are compressed, the adhesive layer will fill the gaps more tightly, eventually breaking and being absorbed by the adhesive layer.
4. Temperature control assistance and pressure relief stage. Most devices are equipped with temperature control systems, and appropriate heating can reduce the viscosity of the adhesive material, promote the curing of the adhesive layer, and avoid the recurrence of bubbles after pressure relief. After completing the pressure maintenance, the equipment will slowly release pressure and then open the chamber to remove the foam free finished product.
3、 The specific role of high-pressure defoamer in the manufacturing of display panels
1. Eliminate adhesive bubbles to ensure display quality. The display panel has almost zero tolerance for bubble defects. The high-pressure defoamer can thoroughly remove bubbles between the bonding layers of polarizing film, OCA adhesive, protective film, etc. through the dual action of pressure and temperature, avoiding defects such as bright spots, dark spots, rainbow patterns, etc. in the finished product, ensuring uniform image display and accurate color reproduction.
2. Enhance the adhesion between materials. In high-pressure and high-temperature environments, the adhesive layer will fully flow and fill the small gaps at the bonding interface, while promoting the curing of the adhesive material, significantly enhancing the adhesion between different materials, and improving the structural strength and service life of the panel.
3. Improve the yield and production capacity. After bonding, the product undergoes high-pressure defoaming treatment, which significantly improves the yield rate and reduces rework and scrap costs. At the same time, highly automated equipment supports multiple batches of continuous operations, which can match the pace requirements of the production line and help enterprises stabilize production capacity.
4. Support large-sized and new display technologies. With the popularity of large-sized LCD TVs, car displays, and flexible OLEDs, the bonding area is becoming larger and the film structure is becoming more complex, which puts higher requirements on the cavity size, pressure accuracy, and temperature control uniformity of defoaming equipment. A fully equipped and customizable high-pressure defoamer can meet the process requirements of products of different sizes.
4、 Typical application scenarios in display panel manufacturing
The application of high-pressure defoamers in display panel manufacturing is very extensive, mainly including the following scenarios: first, defoaming of TN, STN, TFT liquid crystal glass substrates and polarizing films after bonding; The second is the defoaming of touch screen glass to glass and glass to OCA optical adhesive after bonding; The third is the defoaming of film materials such as heat dissipation film, explosion-proof film, and protective film in OLED display modules after bonding; The fourth is the panel manufacturing process that requires higher reliability, such as in car displays and medical displays. It can be said that any display product that involves soft bonding and hard bonding processes cannot do without the high-pressure defoaming process.
5、 How to choose a suitable high-pressure defoamer
When choosing a high-pressure defoamer, it is recommended to focus on the following aspects:
1. Chamber size and volume. Choose according to the maximum size and single batch processing capacity of your own product. If the cavity is too small, it cannot meet the requirements of large-sized panels, and if it is too large, it will waste energy consumption and space.
2. Accuracy of pressure and temperature control. The display panel process requires high uniformity and stability of pressure and temperature, and equipment with high pressure display accuracy and good temperature control uniformity should be selected to ensure consistent processing results for each batch.
3. Safety performance. The high-pressure defoamer belongs to the category of pressure vessel equipment. It is necessary to confirm its safety level and protective design, such as whether the pressure gauge, safety valve, quick opening safety interlock device, etc. are complete and effective, and choose legitimate products that meet the standards of pressure vessels.
4. Degree of automation. Equipment with high degree of automation supports programmed setting of parameters such as temperature, pressure, and holding time, making it easy to operate and less prone to human error, making it more suitable for large-scale production.
5. Manufacturer's strength and after-sales service. It is recommended to choose a defoamer manufacturer with years of industry experience and independent research and development capabilities, and confirm whether they provide installation, commissioning, operation training, and timely technical support.
6、 Precautions for use and maintenance
High pressure defoamer belongs to special equipment, and operators must undergo training before they can take up their posts. Attention should be paid when using: No one is allowed to be on duty during work, and operators should patrol the side of the equipment. It is forbidden to face the tank cover and the joint of the tank cover directly to prevent hot air from rushing out and injuring people; Before putting into production, the internal debris of the equipment should be cleared, and it is strictly prohibited to continue working in case of gas leakage, pressure gauge or safety valve failure, etc; Regularly inspect and test the tank body, safety valve, pressure gauge, and quick opening safety interlock device; Cut off the power after work and do not place any debris in the tank; After each process, the temperature inside the tank is relatively high, so be sure to take measures to prevent burns when picking up the goods.
Conclusion
Although the high-pressure defoamer is only one link in the manufacturing process of display panels, it is a key equipment to ensure product yield and quality. Since its establishment in 2007, PowerDe Automation Precision Equipment Co., Ltd. in Shenzhen has been rated as a national high-tech enterprise for four consecutive years. It has nearly 100 patented technologies and has accumulated over 17 years of research and manufacturing experience in semiconductor vacuum bonding, display equipment, and other fields. Its high-pressure defoamer adopts SUS304 stainless steel tank body, meets the safety standards of Level 2 pressure vessels, and provides customized specification services, which can provide reliable defoaming solutions for manufacturing enterprises such as display panels and touch screens. If you are selecting a production line, please feel free to contact Baode for more technical support.
