Recently, researchers from ITMO University and the Institute of chemistry of St. Petersburg State University announced that the team has developed a new laser-induced copper deposition method, which can efficiently print and engrave copper micro pattern coating on the glass surface, which is not only faster but also more economical.
This process uses a commercially available nanosecond fiber laser with a maximum average power of 20W. It is reported that this method uses deep eutectic solvent and combines the advantages of existing methods. At the same time, it makes the printing process cheaper and 100 times faster than the traditional method. After successful printing, these micro patterns can be used in various devices, such as chemical sensors, flexible electronic products and anti-theft systems.
The electronic motherboard and the printed circuit board are covered with a number of conductive micro patterns, which are connected with each other and connected with other components of the motherboard. The pattern itself can be produced by lithography and other methods. Lithography is a deep printing technique that transfers patterns from one coil to another and then electrodeposits.
However, the lithography process is usually time-consuming, and it usually takes about 40 hours to create a pattern on a chip. In addition, other methods often require expensive equipment and a large amount of solvent when covering copper layer on materials. In general, these methods are not economical and feasible in small batch production.
In general, direct laser writing and chemical deposition are more effective methods. These methods can produce micro patterns faster, more environmentally friendly and more flexible. However, they still need to use expensive femtosecond lasers and toxic solvents, and their stability will be damaged by external conditions.
It is reported that the preparation of micro patterns is usually completed in several stages. First, researchers remove dirt, dust and fingerprints from the glass surface, because any residue left on the surface will affect the subsequent chemical processes and the interaction between the laser and the surface. Then, the surface was prepared by laser-induced microplasma. At this stage, the glass needs to be placed on the titanium plate, and then treated with the plasma generated by laser radiation. Therefore, the combustion products and oxides of titanium will produce a dark copper green in the form of small particles, forming additional crystallization centers. This process changes the surface of the glass and increases its adhesion.
Then, the deep eutectic solvent made of tartaric acid, copper acetate and choline chloride was placed on the glass. The composition of this solvent is cheaper and more environmentally friendly than the existing methods, and it can quickly decompose high concentrations of metal salts at higher temperatures. This is necessary for more efficient synthesis of copper wires on glass. At the same time, compared with organic solvents and water-based solvents, deep eutectic solvents can be stored for a longer time and use less.
Then, it is necessary to add another layer of glass on the solvent lubricated surface to remove bubbles, so that the solvent can diffuse more evenly and remain in the processing area. When exposed to high temperature and laser radiation, the solvent will thicken and cause Noah effect, making the liquid diffuse from the center of the glass to the edge. This design effect is jokingly called "sandwich" by researchers.
Finally, the interlayer is irradiated by laser again, forming micro patterns on the underlying glass that were previously designed using graphics software. According to the researchers' current observation, they can form any shape. For example, circles and lines can be used for SPEs (screen printed electrodes), or complex shapes with multiple angles can be used for multi-functional sensors.
This new method can be applied to different fields, such as the development of chemical sensors. These devices can respond to changes in the content and volume of components in the chemical environment.
This method can also be used to manufacture RFID tags, which are commonly used in anti-theft and other application scenarios. Because this new method can create a very complex outline, it can finally trace the source and determine which brand store a product comes from.
However, according to the researchers, these are not the only applications: "usually, electronic circuit boards with wear patterns will be disposed of. However, our method can refurbish it." Said Ekaterina avilova, a researcher at ITMO international laser micro and nano technology L. "We also hope that the above methods can be successfully applied to flexible electronic products, because our technology can be used to design flexible screens or physiological sensors."
Source: OFweek
