MANUFACTURING EQUIPMENT
Once used to bond the vast majority of electronic components, lead solder has come under fire because of health and environmental concerns. With the RoHS Directive in effect in the European Union and increasingly becoming a de facto requirement in other parts of the world, researchers and manufacturers are investigating alternative bonding techniques. Some scientists at the Technische Universität Braunschweig (TU Braunschweig; Braunschweig, Germany) believe that sintering is a viable method. The process makes use of a drive cylinder developed by TOX Pressotechnik (Weingarten, Germany).
Lead-tin solder melts at a relatively low temperature, and research into alternative alloys typically runs up against the need to expose the replacement material to a higher melt temperature. Sintering, on the other hand, can produce strong, reliable lead-free bonds at relatively low operating temperatures, and the process does not require the bonding material to enter the liquid phase.
The sintering method developed at TU Braunschweig relies on a customized drive cylinder from TOX Pressotechnik. Using a TOX PC 050.048 and a c-frame press with a TOX Powerpackage drive cylinder, the group demonstrated the efficacy of the joining method on semiconductor chips.
Applying 2 to 5 seconds of constant pressure is sufficient to create a strong bond between the electronic components and the substrate. The thermal and electrical conductivity of the resulting bond has a >300°C loading capacity. This property opens up new possibilities for the design of electric and electronic assemblies, according to the firm.
