Microwelding of plastics by fiber laser
The application of an innovative irra-
Task diation strategy for introducing the
energy is required, as the intensity
In recent years, laser-beam welding of the focused fiber laser beam
of plastics has become an established (106 W/cm2) is much higher than the
processing technique for many indus- usual values for plastics welding
trial applications. It has limitations, (300 W/cm2). By using a highly dynamic
however, with respect to weld seam rapid circular movement along the
width and operating speed. New deve- direction of feed, welds can be made
lopments in medical and biotechnolo- without destroying the material even
gical microsystems have increased the at great intensities.
requirements which have to be met in
the laser welding of plastics. The widen-
ing of the range of materials used in
microsystems engineering to include Results and Applications
plastics has both opened up new pro-
500 µm spects and created new requirements With the new irradiation strategy and
for innovative concepts and methods use of the fiber laser, microfluidic com-
that can be applied. ponents made of PMMA and PC can
be sealed along the complex weld con-
Production techniques are required tour with a laser output as low as 3.5
which will enable plastics to be reliably W and an operating speed of 2 m/min.
welded at geometries of 100 µm. On The width of the weld seam is less
the basis of a fiber laser and an inno- than 500 µm, and a cycle time of
vative irradiation strategy, a new tech- below 6 s can be achieved with cor-
nique has been developed for the laser responding scaling of the process para-
welding of plastics. meters. On the polycarbonate samples,
weld seams with a good visual appea-
rance can be produced at an output
of 8 W and a feed rate of 18 m/min.
Above: Light-microscope image
of two 120 µm-wide weld seams Method The weld seam width can be reduced
on a sample of polycarbonate. to 100 µm. The new process has great
Below: Welded microfluidic com- In the tests, a fiber laser with a wave- potential for use in the large-scale pro-
ponent made of PMMA with a
complex channel structure.
length of 1112 nm and a maximum duction of microfluidic components.
output of 9 W is used as the beam
Subject to alterations in specifications and other technical information. 04/2007.
source. Thanks to its excellent beam
quality of M2 < 1.1 a focus diameter of
30 µm can be attained for a working Contact
distance of 100 mm.
Dipl.-Ing. A. L. Boglea, Tel.: -217
Dr. A. Gillner, Tel.: -148
Fraunhofer-Institut für Lasertechnik ILT Director: Prof. Dr. rer. nat. Reinhart Poprawe M.A.
Vice Director: Prof. Dr. rer. nat. Peter Loosen
82 Fraunhofer ILT Annual Report 2006 Steinbachstraße 15, 52074 Aachen, Germany
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