Method and means for connecting thin metal layers.
|563 - Abstract:|
|The European Space Agency (ESA) is offering an innovative method for bonding two thin metal layers applied to flexible substrates. This connection is achieved by micro (hollow) rivets, providing a mechanical and electrical link through the use of modern laser technology. Previous attachment procedures such as welding, soldering or the use of adhesives carry many disadvantages require certain material properties that are unfeasible with flexible surfaces. This method is reliable and doesn’t require large contact areas, effortlessly providing a mechanical and electrical bond. License agreement is sought.|
Protected in this patent is a method to mechanically and electrically connect two thin metal layers. Specifically, this method is suitable for thin layers mounted on flexible substrates and was originally developed for the bonding of thin solar cells and flexible, film-reinforced contact strips.
Nowadays there is a big research effort going into solar cell technologies, embedded in the push for greener energy sources, as well as energy generation in remote areas, such as with spacecrafts. Thin-film solar cells are among the technologies being developed, and when combined with flexible substrates and circuit boards, the very interesting concept of flexible solar cells comes to mind. These have several advantages over rigid products, namely in their installation and eventual portability, however, present some technical challenges.
Understandably, a flexible solar cell would require an also flexible and consequently thin electrical conductor to deliver the produced energy to the end consumer. These requirement for the electrical wiring make traditional bonding techniques obsolete, as soldering and the use of contact adhesives require high contact areas or that the substrate presents sufficient mechanical rigidity to resist the high pressures on the surfaces during the bonding. The thermal resistance of the materials involved must also be taken into account, as soldering requires high temperatures that may be incompatible with flexible substrates.
Current laser technologies include the connection of metal parts through irradiation, soldering without any additional materials by melting and mixing the materials involved. It is with the application of pulse laser radiation that the inventor sought to overcome previous hurdles. The protected process enables the micro riveting of thin layers and films, therefore enabling the mechanic and electrical connection of the materials involved. This method is suitable for flexible substrates, requiring little space and avoiding the requirements for special and complex materials and surfaces.
The hollow riveting process is preceded by some surface treatment steps, namely the removing of extra layers above the thin-film that is to be bonded. These are also laser based, a positive feature, since it eschews the need for different machinery and setups for the connection procedure. The strength of the bond can be easily controlled through the number of rivets, as the process allows the simultaneous multiple riveting.
Innovations and advantages
This invention provides a clear advantage over prior art, solving a bonding issue on thin-film solar cells mounted on flexible substrates. Although this was its envisioned application when being developed for ESA, this technology is applicable to a much broader spectrum of fields of expertise.
By providing a solid, robust, simple and relatively small attachment method, hollow riveting removes the need for high technical, procedural and technological efforts, special materials or surfaces when considering the bonding of two metal films.
Domains of application
Any industry dealing with thin-films of metals that require the bonding of said materials would be highly benefited by the knowledge contain in this patent. For example purposes the flexible solar cell market is mentioned, but the applicability of the invention is not restricted to this.
Last update: 25 March 2013