Glass is one of the oldest commodities ever manufactured. Humans have been creating decorative glass for millennia. At first, we used rudimentary molds prior to glass blowing was invented in the Middle East. Various major players adapted and evolved the glass manufacturing process in subsequent centuries, with translucent broadsheet and crown glass windows preceding the first clear, colorless panes. Today, manufacturers exploit a range of techniques to produce high-quality glass with a range of aesthetic and functional qualities, including selective opacity and even patterned surface etching.
Micromachining glass is not a novel concept, but it has reached new levels of maturity in recent years. The onset of high-precision laser-based etching processes has dramatically improved our ability to carefully modify challenging substrates, including hard transparent surfaces like plate glass. However, the path to small-scale surface modifications of glass has been long and complex. Here we will take a brief look at the history of glass micromachining.
What is Etched Glass?
Etched glass is typically decorative, though the increasing precision of glass micromachining techniques has opened opportunities for high-precision optics and signal transmission. In the glass micromachining process, minute amounts of glass surface matter are removed via abrasion, chemicals, or powerful precision lasers.
Glass Micromachining Methods
Micromachining glass using caustic acids is ideal for creating intricate decorative designs, but it involves the use of highly toxic chemicals, and the process can be a slow. Sandblasting was introduced to accelerate workflows. This uses a jet of highly-pressurized abrasive media to remove surface molecules via abrasion. Initially, this process was conducted by hand, but process automation and improvements to CNC machining have enabled automation of large-scale glass sandblasting processes.
To combat the use of caustic acids and the un-precise methodology of sandblasting, advances in laser technology have offered a range of functional advantages. Laser micromachining of glass allows for fine contoured detailing and rapid lead times. Essentially this is a blending of the best aspects of the acid etching and sandblasting. A typical laser-based micromachining system uses either dry or wet etching methods.
Wet etching refers to the removal of sample material via ablation, followed by chemically-assisted etching. A high powered laser illuminates the substrate surface in a pre-defined pattern before the piece is washed in a supplementary acid bath. Though wet etching is low-cost and reliable, it is limited for etches nothing less of 3 micrometers.
Dry Etching refers t othe process of texturing glass using ablation alone. This method allows for capabilities to create smaller feature sizes. This method relies heavily on laser technology capable of mitigating thermal side-effects and structural defects that can cause warping.