In the manufacturing process of solar cells, in order to prepare solar cell contact electrodes, it is necessary to print metal paste on silicon wafers by screen printing technology. After the sintering process, front and back electrodes are formed on the surface of the solar cell, through which the current of the cell is collected and transmitted.Millennial 3D microscope can detect the number of grid lines and pyramids on the photovoltaic cell through the system software, helping users to master the quality of solar cell cleaning, texturing, and screen printing processes.

Screen Printing Process

The process steps of screen printing are: printing the back electrode with silver paste→drying→printing the back field with aluminum paste→drying→printing the front grid with silver paste→drying. The printed pattern is required to be complete, clear, uniform and symmetrical.

When performing screen printing, the printing pattern should be designed first and made into a screen. The meshes that need to form the graphics part on the screen are transparent, and the non-graphics parts are closed. When printing, spread the slurry on the screen, the blade of the scraper is close to the screen surface of the screen to scrape the slurry horizontally, and apply appropriate pressure to make the screen contact with the silicon wafer, and the slurry is squeezed out of the mesh and then adhered on a silicon wafer. Because there is a gap between the stencil and the silicon wafer, the stencil will use its own tension to contact the silicon wafer for an instant and then immediately break away from the silicon wafer and rebound. Graphically defined areas of the board are adhered to the slurry.

Screen printing for silicon PV devices

Using screen printing to make solar cell electrodes has the characteristics of low production cost and high production capacity, and is currently a widely used method in large-scale production. In addition to screen printing, there are other methods to make electrodes, such as groove buried grid method, inkjet printing method, stencil printing method, etc., but most of them have not been applied to large-scale production because of high cost or immature technology.

Millennial 3D Microscope

E-mail: market@millennialsolar.cn

Millennial 3D Microscope is a high-speed confocal scanning microscope for accurate and reliable 3-dimensional (3D) measurements. Real-time confocal microscopy images are realized by fast optical scanning modules and signal processing algorithms.

Millennial 3D Microscope has high-definition confocal microscopy technology, precise high-resolution scanning technology, and solvent materials that are difficult to distinguish on the surface can also be presented. The Z-axis display resolution is as high as 1nm, which can accurately obtain tiny shapes.

Based on the principle of optical technology, combined with precise Z-direction scanning module and 3D modeling algorithm, etc., non-contact scanning is performed on the surface of the device and a 3D image of the surface is established. Quantitative detection of the number of pyramids in order to feedback the quality of photovoltaic cell cleaning, texturing, and screen printing processes.