Brochure Packaging

Brochure Packaging

The assembly of laser and optical components demands a number of different processes in the areas of packaging and joining technology. According to the function of the components, different requirements have to be fulfilled.

Packaging and Joining Technology

High-power diode lasers have established themselves as beam sources and are used in many different areas, for example, in medical technology, materials processing and the printing industry. They can also be used as pump sources for solid state lasers. Reliability, life time as well as output power and spectral characteristics of high power diode lasers are significantly influenced by the packaging and joining technology. Joint connections between heat sink and diode laser bar serve to optimally couple them thermally and simultaneously define the optical interface while requiring high precision reaching down to the sub-μm range. The Fraunhofer Institute for Laser Technology ILT has comprehensive experience in the use of hard solders such as AuSn on thermally expansion-adapted heat sinks, from metallurgy via soldering process all the way to quality control in the sector of high precision assembly.

For our customers we develop and realize individual solutions for the soldering of laser components. For example, we join laser crystals of different dimensions on fluid and conduction cooled heat sinks by means of soft solder.

By optimized design of the joining partners, layer materials and dimensions as well as solder and joining process, we can ensure a tension-free and long-term reliable connection with high thermo-mechanical strength.

Innovative soldering and bonding procedures enable us to mount all the optical components of a laser setup like mirrors, lenses and crystals by means of automated processes with high precision, long-term stability and cost-effectiveness.

Heat Sink Design

For over ten years, the Fraunhofer ILT has been developing cooling concepts and heat sinks for high-performance diode lasers. Today we concentrate on developing expansion-adapted heat sinks, increasing life time and reducing costs. For this, we investigate and develop passive as well as active heat sinks. Particularly in the sector of thermal design, we have gained significant experience in the last few years, which flows also into the development of heat sinks for solid state lasers.

The Fraunhofer ILT offers its customers a wide spectrum of R&D services in this area:

  • Design and optimization of heat sinks under the aspect of thermal modeling (FEA) and simulation of fluids (CFD)
  • Identification of the thermal expansion coefficient by means of speckle interferometry
  • Identification and analysis of thermal resistance

Using in-house developed burn-in systems, we conduct tests to identify life times of high-performance diode lasers, whereby we investigate nearly all the required test parameters in continuous and pulsed operation at different temperatures.

Soldering Technology

In the sector of high-performance diode lasers, the Fraunhofer ILT has gained significant, long-term experience in assembly and soldering technology with the soft solder Indium. Thanks to this, it has established a series of soldering systems for various applications. In addition to the hard solder AuSn, we use numerous silver and tin solders and place sophisticated analysis technique at our customers’ disposal:

  • Thin-film coating of solders such as In, InSn and AuSn
  • Analysis of metallurgy and solder alloys through, e.g. shear test, ultrasound microscopy, Calotest, SEM and EDX
  • Electro-optical analysis of joined components

We use these analyses to develop tailored solder joints. To reach their long-term stability, we adapt the solder connections to the ideal stoichiometric composition of the individual joining partners.

Assembly Procedures and Plants

The assembly of laser components demands, on the one hand, a high precision tool to place and align the components, on the other, a very exact measuring technology to check the result. To exactly position components, we develop and optimize process adapted vacuum grippers. Thanks to the ultra precise surface manufacture of these grippers, we are able to guarantee exact alignment. In a subsequent process step, we bond or solder the components positioned according to individual specifications. Components of different dimensions, from individual emitters via diode laser bars all the way to solid state laser crystals are joined. According to demands, we use gold-tin solder consecutively in several steps or also different solders. We reach a precision under 1 μm in three spatial axes. According to requirements we optionally align the components actively or passively and join them afterwards. By using these techniques, we attain ultra precise alignment as well as extensive long-term and temperature stability and cost-efficiency.