Screen printing technology for solar panel electrodes

Screen printing, a printing method that uses a screen mesh screen made from screen printing mesh such as polyester or stainless steel and various metal fibers, works on the principle that the mesh holes in the graphic part of the screen allow the ink to pass through, while the non-graphic part is blocked. By applying pressure with screen printing squeegee, the ink can precisely pass through the fine mesh of the screen mask, achieving fine printing on the substrate objects . Screen printing, with its advantages of simple operation, low cost and suitability for large-scale production, plays a crucial role in the manufacturing of solar cell electrodes and can be regarded as the top priority in the process management of solar cell manufacturing and production.

In the manufacturing of photovoltaic cells, screen printing is mainly used to prepare electrodes and anti-reflection film layers. This process consists of two procedures: SP and DUP. The SP process involves the printing of the back electrode, back field and positive electrode electric field, while the DUP process includes the printing of the back electrode, back field, positive electrode main gate and fine gate. A total of four processes need to be completed.

In the first place, through a specially designed screen template, conductive materials such as silver paste or aluminum paste are precisely printed on the silicon wafer to form fine grid lines and busbars, thereby constructing the positive and negative poles of the solar cell and completing the collection and output of current. This process has extremely high precision requirements because every tiny electrode will directly affect the conversion efficiency of the final solar cell.

And in this whole process, the screen printing squeegee specially-made for photovoltaic cell printing are vital. The function of the screen printing squeegee is to press the paste into the holes of the screen at a certain speed and Angle. During the printing process, the solar screen printing squeegee needs to apply a certain pressure to the screen. The pressure must be within an appropriate range. Excessive pressure will increase the friction between the solar screen printing squeegee and the screen, causing the screen to deform and the printed pattern to be misaligned with the screen pattern. If it is too small, too much slurry will remain on the screen.  

Solar squeegee is a new generation of one-piece squeegee specially developed for the narrow line width printing of battery cells. Compared with the traditional sanding squeegee, it has significant effect on wet weight control, printing life and efficiency improvement, etc. Using this squeegee can achieve the purpose of cost reduction and efficiency improvement. It can also be customized into different shapes according to the different requirements of customers to adapt to the printing of different solar panel electrodes, such as the single side, double stick, through-channel, cap-head and other customized type glass fibre board squeegee.

The glass fibre board screen printing squeegee for solar photovoltaic uses imported molded rubber as scraping blades. This can effectively ensure that the hardness of all parts of solar screen printing squeegee is consistent, reduce the occurrence of false marks and increase the service life. The special glass fiber board for solar photovoltaic is inlaid with high-strength glass fiber board in the middle of the squeegee, which makes the solar squeegee less likely to deform during the printing process and has better stability. In addition, it can be directly installed and used using the positioning holes on the fiberglass board and the screen printing machine fixture, avoiding the instability of installation relying on experience and eliminating the need for re-grinding before use. In addition, It has excellent solvent-resistant performance, with single-sided printing reaching over 30,000 times.

Solar squeegee need to be stored indoors at 40°C or lower. Do not store in places with high temperature and humidity, direct sunlight and UV rays. Recommended storage conditions are 23°C±2°C and 60% or lower humidity. Besides, the screen printing squeegee for solar panel printing should avoid heat generating equipment or dusty places and prohibit bending and heavy pressure. Stack flat and stack no more than 20PCS.

Screen printing is the core of battery cell process management. The screen printing process gathers half of the process personnel in the entire battery cell production line and holds a very important position in process improvement and process verification.

For more details about sloar squeegee, please contact us at +86 15097355251