Processing of glass

The femtosecond laser micromachining technique has brought transparent materials processing to the next level. Complex structures can now be precisely fabricated by selectively removing material through drilling, cutting, and milling.

Glass Metal Polymer Other materials
Glass

Bottom-up milling of glass

Conventional laser milling strategy struggles to achieve high aspect ratio geometries, as ablation debris accumulates within the ablation area, preventing further material removal and resulting in saturation of ablated depth. Alternatively, in the bottom-up milling technique, the laser beam is focused at the bottom of a sample. This method allows all ablation products to be removed through the backside of the sample, enabling the formation of high aspect ratio geometries in glass.

FemtoLux 30 GHz burst function was combined with bottom-up milling to achieve high process throughput rates. With precise and flexible control of the burst energy and no. of pulses in theburst, it is possible to precisely control the thermal stress generated in the glass substrate. With correct parameters, the material removal process switches to laser induced material fracture and glass particles are being removed in a particle form. In result, with 25 pulses in GHz burst it is possible to achieve material removal rates of 600 mm3/min. The bottom-up milling strategy not only excels in high throughput rates, but also offers zero-taper capabilities of forming various holes and channels with depth reaching of tens of millimeters.

Schematic of top-down milling (TDM) and bottom-up milling (BUM) techniques

Schematic of top-down milling (TDM) and bottom-up milling (BUM) techniques.

Manufacturing examples

Bottom-up milling of 200 µm holes in SCHOTT BF33/D263 glass.

Courtesy of FTMC.

Bottom-up milling of fused-silica glass.

Courtesy of FTMC.

Bottom-up milling of fused-silica glass.

Courtesy of FTMC.

Bottom-up milling of fused-silica glass.

Courtesy of FTMC.

Recommended products

FemtoLux

Industrial Femtosecond Lasers
  • 50 W / >300 µJ at 1030 nm
  • 20 W / >50 µJ at 515 nm
  • 10 W / >25 µJ at 343 nm
  • < 350 fs – 1 ps
  • Single shot to 4 MHz (AOM controlled)
  • MHz, GHz, MHz+GHz burst modes

Similar applications

UVFS milling
Glass milling in GHz burst mode

Femtosecond laser processing of glass stands out for its exceptional quality, thanks to the ultra-short pulse duration. However, when compared to traditional methods, femtosecond lasers often fall short in throughput, limiting their broader application. To overcome this limitation, GHz burst technology can increase the process throughput by dividing the high energy pulse into multiple ones.
Bottom-up milling of 200 µm holes in SCHOTT BF33/D263 glass.
Bottom-up milling of glass

Conventional laser milling strategy struggles to achieve high aspect ratio geometries, as ablation debris accumulates within the ablation area, preventing further material removal and resulting in saturation of ablated depth. Alternatively, in the bottom-up milling technique, the laser beam is focused at the bottom of a sample. This method allows all ablation products to be removed through the backside of the sample, enabling the formation of high aspect ratio geometries in glass.
Laser-based Bessel beam scribing of 4.8 mm soda-lime glass
Laser-based Bessel beam scribing

Bessel beam scribing is the most efficient laser-based, kerf-less method for scribing glass. This technique introduces intra-volume voids, followed by mechanical or thermal separation, resulting in smooth sidewall roughness and as it requres only a single laser pass, high scribing speeds can be achieved.
300 µm hole drilling in thin borosilicate glass.
Thin glass cutting

Processing glass substrates thinner than 0.5 mm presents significant challenges due to their fragility and susceptibility to cracking under excessive thermal loads. Femtosecond lasers are ideal for processing thin glass substrates because their ultra-short pulse duration minimizes thermal accumulation, resulting in superior quality.
Femtosecond laser induced selective etching of various diameter holes in fused-silica.
Femtosecond laser induced selective etching

Femtosecond laser induced selective etching is a two-step process where focused femtosecond laser pulses modify the material structure, followed by chemical etching that selectively removes the laser-modified regions. This technique enables precise taper-free 3D microfabrication in transparent materials, achieving superior surface roughness in the range of hundreds of nanometers and the capability to operate at wafer-level scales.
GHz burst assisted percussion drilling of high aspect ratio holes in EXG glass.
Through glass vias (TGVs) fabrication

Formation of high aspect holes in glass substrates is becoming an increasingly important topic, especially in semiconductor field. With the help of femtosecond lasers it is possible to form low degree taper and high aspect ratio TGVs in glass with high quality – low chipping, absence of cracking and smooth hole inner wall.
All applications