Laser welding of polymers

In medical device technology, laser welding of polymers is a matter of particular interest, which we are currently advancing intensely in cooperation with partners like Treffert.

Lasers for every kind of application

All thermoplastic resins and thermoplastic elastomers – unfilled or filled to a degree – can be joined pressure-tight and with nearly base material strength. For the typical overlap welding method, the joining
region is completely inside the welded parts. With diode lasers, diode pumped Nd:YAG lasers and CO₂ lasers with wavelengths of 808, 940 and 1064 nm ROFIN provides all relevant laser source technologies.

Transparent and colored

All commonly used polymers are more or less transparent (in undoped condition) in the infrared wavelength range of the laser sources (except CO2 lasers). Filler materials, usually pigments, provide for the absorbtion of laser energy. Many color pigments absorb within the infrared range and can be used for laser welding. For clear and bright colors, pigments which are more flexible to use, have been developed. They absorb only in the wavelenght range which is relevant for the laser weld, but do not modify the coloring of the polymer significantly.

Clean surfaces

In contrast to competing methods like adhesive bonding or ultrasonic welding there is no deleterious generation of micro particles, adhesive residues or roughness. Provided that one of the joining members is absorbing the laser beam, both bio-polymers (transparent) and colored polymers can be welded. Some application examples are: sensors, filters, micro cameras, plastic bags for fluids, tube connectors, balloon-tipped catheters and microfluidic devices.