a) b) 200 μm 500 μm
www.industrial-lasers.com MAY/JUNE 2015 Industrial Laser Solutions 35
highly reliable, and robust laser for micromachining and medical
applications (FIGURE 1). This laser is widely deployed in demanding medical and manufacturing applications around the world.
To demonstrate the capability of the ClearShape femtosecond laser process, the Spirit laser has been applied to machine
chemically strengthened Gorilla Glass (Corning). Glass with thick-
ness of 0.55mm and
depth of compression
layer (DOL) of 20µm
was used for the test.
The cutting speed of up
to 4 m/s was achieved
using the ClearShape
process in combination
with this laser. A chipping size of < 1 µm and
average cut-edge roughness (Ra) of <0.1 µm was
observed (FIGURE 2).
The high machining
speed of > 1 m/s allows
a process time of <1s for
a whole-profile cut of a
smartphone cover glass for a 6 in. display.
The cutting step is followed by self-cleaving
of the materials, with no mechanical cleav-
ing step. The industry standard to gauge the
effectiveness of the glass laser cutting pro-
cess is to perform a four-point bending test
of as-cut samples. A four-point bending test
shows a very high bending strength of up
to 700MPa for different types of chemically
strengthened glasses without a post-pro-
cessing step (FIGURE 3).
In addition to chemically strengthened
glass, the process can machine unstrength-
ened glass that is straight- or curvilin-
ear-cut, and has internal closed-shape features. What’s more, complex combinations
of multilayer glasses can be processed.
Additionally, this method has been applied to machining sapphire,
which is highly scratch-resistant and, therefore, an appropriate
material for smartphone camera windows or wristwatch covers.
FIGURE 4 shows circular windows with a diameter of 6.4mm cut from
0.43mm-thick sapphire using this process. Sapphire windows can
be machined with very high quality (minimum chipping) and high
The ClearShape patent-pending pro-
cess has been developed to process
optically transparent, brittle materials.
The results presented in this article were
obtained using the Spirit industrial fem-
tosecond laser at the 1040nm wave-
length, avoiding the need for more dif-ficult-to-handle, higher-harmonic laser
irradiations such as visible or UV laser
light. Our results show that this robust
and reliable femtosecond laser, in com-
bination with the novel ClearShape
process, results in an optimal solution
FIGURE 2. An example of straight line cut in chemically strengthened Gorilla Glass
from Corning (0.55mm thick and DOL of 20 µm) with the ClearShape process using the
Spirit 1040-IMC laser without any post-processing. A cutting speed of up to 4 m/s was
achieved. The top view of the cut edge shows a very high cut quality without chipping on
the surface (a), while the side view of the cut edge shows a clean, smooth surface with
roughness (Ra) <0.1µm.
FIGURE 3. Results of
tests for Gorilla Glass
(0.55mm thick and DOL
of 20µm) and IOX-FS
glass (0.55mm thick and
DOL of 30µm), cut using
the ClearShape process
in combination with the
Spirit 1040-IMC laser.
The tests show very
high bending strength
for as-cut glass with no
post-processing (up to