Friedrich-Alexander-Universität Erlangen-Nürnberg

Laser-based electromechanical contacting

Laser-based electromechanical contacting

Adaptronic components are used for monitoring the health of structural components which are loaded with vibrations, and they can also be used to dampen these vibrations or to harvest vibrational energy. In order to allow the application of piezoceramic modules for the active damping of structural components, it is necessary to establish a material connection between the active component and the surrounding material. The research objective of the CRC/Transregio 39, "PT-PIESA" is to directly integrate the sensors or actuators into a lightweight material and to merge the production process chains of the active and the structural part.

Figure 1: comparison of conventional process chain and PT-PIESA process chain

The aim of this particular project (sub-project A4) is to investigate the fundamentals for the mass production of electromechanical joints on piezo-ceramic modules. Since, after contacting, the modules are processed by aluminium casting or hot lamination with fibre reinforced polymers, the junctions must have a high mechanical strength as well as temperature resistance.

 

The contact pads on the piezoceramic modules have a very thin metallisation which is sensitive to high temperature gradients. For processing via aluminium casting, the modules need to be contacted by brazing. In order to create joints which are thermally stable without damaging the sensitive modules, a new system technology has been put into operation which uses single metal droplets for contacting. The brazing material preforms are separated and then molten with a single laser pulse. This „laser droplet joining“ technique can also be combined with an electromagnetic levitation technique, in order to facilitate the singulation of the preforms.

 

Results

Piezoceramic foils can be reliably contacted by droplet soldering. First experiments with braze droplets on piezoceramic modules for aluminium casting show that mechanically and chemically stable joints on sensitive substrates can be produced by the Laser Droplet Joining technique.

Figure 2: Solder spot on a Ni/Cu metallized piezoceramic, produced by laser droplet joining
Figure 3: X-ray image of a piezoceramic module which was contacted by brazing and cast into aluminium; the compound is free of damage

This program is funded by the

German Research Foundation

SFB/TR 39

 

References:

 

ALBERT, F.; PFEIFFER, C.; SCHMIDT, M.; GEIGER, M.; FLÖSSEL, M.; MICHAELIS, A.: Laser soldering and laser droplet joining for mechanical and electrical contacting of LTCC/PZT laminates. In: Journal of Laser Micro/Nanoengineering, Vol. 6, No. 1, 2011

Mission

SAOT provides an interdisciplinary research and education program of excellence within a broad international network of distinguished experts to promote innovation and leadership in the areas

Optical Metrology
Optical Material Processing
Optics in Medicine
Optics in Communication and Information Technology
Optical Materials and Systems
and Computational Optics.