Background

Available active solder pastes are almost exclusively based on silver and silver-copper alloys, which limits the temperature stability of the composites. Higher temperature stabilities can be achieved with active solders based on precious metals (Pd, Pt), but these are significantly more expensive. There is therefore a need for new types of active solder alloys that enable stable composites for application temperatures of 1000 °C to approx. 1200 °C. In addition to the main interest in the feasibility of corresponding composites, the pure metallisation of functional ceramic surfaces for electrical contacting is also of interest. 

Active solder pastes are usually required in small quantities, but in a large variety, specialised and optimised for defined applications. With ultrasonic plasma atomisation, it is possible to realise small batch sizes and alloy systems that are difficult or impossible to mix using melting metallurgy. To this end, new active soldering systems, the fundamentals of which are already known, are to be evaluated, optimised and adapted. In addition to powder production, matching the pastes to the active solder application is a very important aspect. Rheological properties and solids content must be adapted for industrial, automated application of the solder pastes using screen printing and dispensing technology. In addition, reliable debinding in a vacuum must be possible. The investigations are supported by statistical design of experiments (DOE) and multivariate data analysis (MVDA) in order to ensure a high level of efficiency with regard to the variety to be analysed and a higher significance of the results.

GOAL

The aim of the research project is to develop temperature-stable active solder alloys that are not based on precious metals, to produce powder using ultrasonic plasma atomisation and to optimise active solder pastes. Active brazing technology enables the realisation of metal-ceramic composites in just a few process steps, as direct wetting of ceramic surfaces is possible. The application of these solders as powders or pastes has advantages over moulded parts (wire, foil) in terms of automated applicability (screen printing, dispensing) and minimises material losses. 

Acknowledgement

The IGF project 22117 BG of the research association Verein für das Forschungsinstitut für Edelmetalle und Metallchemie (fem) is funded via the AIF as part of the programme for the promotion of joint industrial research (IGF) by the Federal Ministry of Economics and Climate Action on the basis of a resolution of the German Bundestag.