Currently, the commonly used solar cell technologies are monocrystalline silicon solar cells and polycrystalline silicon thin film solar cells and other categories. In solar cell production, solar cell units are processed to form photovoltaic modules. In order to facilitate reliable data collection for tracking and identification of solar modules, marking is required after the glass is loaded in the early stage and again after the subsequent backsheet is laid.
QR codes are widely used in industrial manufacturing due to their ability to store larger amounts of data, and this is also true for solar module production. Through laser marking, unique QR codes with specific coding rules are "implanted" in the production process to ensure that each process and the use of raw materials can be traced, thus realizing effective supervision and tracking of quality control. And the use of laser marking can avoid the traditional labeling, spray code and other ways of pain, to solve the problem of low efficiency of the traditional marking methods, and laser marking markers for permanent, for a long time in the outdoor wind, rain and sunshine of the solar cell, does not fall off, does not fade, to do at any time to carry out accurate data collection.
However, marking on glass substrates is not an easy task, mainly due to the hardness and brittleness of glass, as well as high light transmission. Nuffield has developed and designed 1064nm industrial grade picosecond lasers with very high stability and critical cold processing characteristics for multi-pass laser marking applications on solar cells.
There is no doubt about the importance of high stability of the laser, especially in the assembly line 7 * 24 operation more mechanical continuity and stable output to ensure the consistency of the marking size and resolution, to help improve production capacity. After a long time of testing, the pulse stability and power stability of this type of laser are <1% RMS, enough to be comparable to the same type of high-quality products on the market.
For hard and brittle characteristics, industrial picosecond laser pulse width is very narrow, only about 10ps, such a narrow pulse width so that the laser energy can not be accumulated on the surface of the material before the end of a pulse, so that the processing of the heat-affected zone is very small. Ultra-narrow pulse width, higher than 30W output power, it is easy to obtain very high peak power, the role of the glass surface, the laser photons directly destroy the bond of the target material, which is relatively speaking a "cold" processing process, the entire process is very clean, conducive to the control of dust, and no mechanical stress, and further This further enhances the quality of the product marking.
The icing on the cake is that industrial picosecond lasers have excellent beam quality (M² <1.3) and a very small spot diameter after focusing, which makes it possible to make fine lines when marking, especially suitable for high-fine-degree processing needs. Another benefit is that it is possible to mark small-size 2D codes in order to adapt to the subsequent application of the metallization pressure, and will not weaken the performance of solar cells.
In recent years, the development of clean energy has emerged both at home and abroad, and China has also put forward a dual-carbon strategy, the favorable environment has driven the shipment of solar cells. As a solar cell processing tool, picosecond lasers are not only used for marking, but also can be used for high-quality cutting, etching, etc. of solar cells, which runs through several production links, and strongly promotes the high-quality production of solar cells.
