Manufacturers of microelectronic components in high-wage countries are nowadays faced with high requirements on flexibility of the production process. In a market characterized by mass production and extreme pricing pressure the only way to compete with low-cost suppliers is to provide highly specialized products with premier quality standards. A key aspect to create such products on short term and even in small lot sizes in a cost-effective way is the availability of tools for a flexible and reliable assembly technology.
Characteristic applications appear in the fields of automotive industry, power engineering and consumer electronic products. Assembly of electronic components and contacting of fine mechanical work pieces are typical examples which require high accurate joining processes with a maximum on process flexibility. An ongoing trend concerning the interconnection technology for such products is the replacement of soldering by welding. This development is driven by the facts that welded connections withstand higher mechanical and thermal stress as soldered ones and the use of (potentially toxic) filler material can be avoided.
Latest developments in the field of laser technology show that laser beam welding is a suitable joining technology for assembly of such products. The combination of high brilliance laser sources with fast galvo scanners enables several novel processing approaches but also places high demands on positioning of the joining partners and the laser beam. Depth and width of the welds are often subjects to severe restrictions in order to avoid thermal damage e.g. crack formation in weld seams or insulating layers. Furthermore some applications require sensitive thermal management by precise beam modulation during the welding process to avoid thermal stress e.g. distortion in thin sheet metal weldings.
To meet the described requirements and enable high productivity for a wide range of products with minimum adaptation costs, the goal of the suggested project is to develop a self-adapting laser welding tool for micro assembly tasks as described. Depending on the application different auxiliaries such as vision system and a positioning device with adaptable grippers will be integrated in the tool to enable the following functionalities:
- Feature Recognition and Positioning: by attaching an on-axis camera system to the welding tool, the position of workpieces in the scan field can be determined precisely. This enables precise positioning of the welds without part-specific adjustment tools.
- Pick&Join: using a suitable gripper, positioning and joining of parts like active and passive electronic components can be combined in one step. Based on the feature recognition ability precise positioning of the parts as well as of the laser beam is assured.
Furthermore welding processes have been investigated. By using brilliant laser beam sources with small focal diameters a stable deep penetration process can be achieved and the energy input into the workpiece is reduced. Nevertheless the small focal diameter produces only narrow seams, which affords a high positioning accuracy of the laser beam on the surface. The needed accuracy can be reduced by the use of spatial power modulation, which has also a positive influence on the process efficiency.
The companies in the project consortium are experienced in the fields of scanner development, part handling and control technology as well as job-shop manufacturing. This ensures an adequate market access and a suitable design of the functionalities adapted to the market needs.