Ultrashort pulse lasers combined with sophisticated self-focusing technology provide the quality and process reliability required to make laser glass welding possible in series production. The unique and excellent properties of glass make it widely used in various high-tech products in different fields such as biomedicine and microelectronics. We’ve previously covered the challenges it poses for manufacturers, particularly in the high-volume, precision glass cutting sector. It also poses difficulties in bonding, both in welding individual glass components together and in welding glass to other materials such as metals and semiconductors.
blend into one
All traditional methods for welding glass struggle to provide the required precision, bond quality and production speed for cost-effective series production. Adhesive bonding, for example, is an economical method but can leave adhesive residue on the part and even requires degassing.
Dielectric welding involves placing powdered material at the point of contact and then melting it to complete the bond. Whether this melting is achieved by an oven or a laser, a lot of heat is pumped into the part. This is a problem for microelectronic devices and many medical devices.
Ionic bonding is an ingenious method that provides extremely high bond strength. Two new, extremely flat glass surfaces are pressed together and literally fused together through molecular bonds. However, it is not practical to do this in a production environment.
Laser glass welding
So, what about laser welding? Glass has many very useful properties, such as extremely high melting point, transparency, brittleness and mechanical rigidity, but it also brings many difficulties to laser welding. Therefore, typical industrial lasers and methods used to weld metals and other materials are not suitable for glass.
Like precision glass cutting, the secret lies in using an infrared wavelength ultrashort pulse (USP) laser. Glass is transparent in the infrared, so a focused laser beam can pass directly through it until the focused beam narrows and becomes concentrated enough to trigger “nonlinear absorption.” This “nonlinear absorption” only occurs in ultrashort pulse lasers with high peak power, and the same thing cannot be accomplished with other types of lasers.
Therefore, in a very small area (usually less than a few tens of microns in diameter) around the focus of the laser beam, the glass absorbs the laser light and melts rapidly. This focused beam is scanned along the desired welding path to complete the bond, just like other forms of laser welding.
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