Technical Background
With the rapid development of laser technology, lasers have been widely used to weld various materials. Glass, being a transparent and brittle material, does not easily absorb traditional laser light, and its high coefficient of thermal expansion can lead to cracking during welding. As a result, traditional laser welding methods are not suitable for glass.
Common methods to weld transparent materials like glass and plastic involve either applying an opaque pigment or adding an intermediate layer to increase laser absorption, or using specialized laser sources to achieve non-linear absorption, thus forming effective weld points. More researchers and engineers are exploring applications of specialized laser sources for laser welding of transparent materials.
Research Progress
In recent years, specialized laser sources have achieved welding for various types of glass and glass-to-silicon welding. Companies like PolaOnyx have used specialized lasers with single-line/multi-line scanning to weld and seal glass. Researchers like Hélie and Tamaki have successfully welded different types of glass and glass to silicon, achieving high bonding strength.
However, many studies indicate that welded fusion zones often take on a droplet shape, with a circular cavity at the top, a molten zone in the middle, and a smaller cavity at the bottom, leading to stress concentration and potential cracks. The droplet shape can also lead to inconsistent welding lines.
Laser Welding of Glass
Experimental Material and Method
The experiment used optical glass with dimensions 25×25×1 mm. The steps for the glass welding experiment were as follows:
- Surface Cleaning: Glass plates were soaked in alcohol for 5-10 minutes, rinsed with distilled water, and then dried with hot air.
- Clamping and Welding: The glass plates were clamped tightly to ensure close contact. It was crucial to have a gap smaller than 100 nm for effective welding.
- Adjusting Focus: The laser focus was adjusted to the interface between the two glass plates. The laser's focal point could shift due to refraction, so careful adjustment was needed.
- Laser Welding: Using appropriate laser welding parameters (power, speed, scan pattern, etc.), the glass was welded by inducing multi-photon ionization, causing the glass to melt and then solidify to form a weld.
Welding Technique with Specialized Laser
The specialized laser allowed for even and consistent welding across the entire area without significant deformation or visible heat damage. The welded area showed no signs of water droplet patterns or cracks, indicating a successful weld with high strength.
Summary and Outlook
The use of specialized laser sources with proper welding parameters allows for successful direct welding of optical glass without adding any fillers. The welded area shows no significant macro or micro cracks, and no evidence of the problematic droplet shape. This ensures high welding strength and avoids crack formation.
With the rapid development of 5G, wireless charging, optical communication, and chip technology, glass has become a mainstream material in various applications due to its low electromagnetic signal shielding, high hardness, lightweight, and suitability for mass production. Glass laser welding is poised to have a bright future with wide-ranging applications.
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