Reactive microjoining and packaging – mechanical, thermal and electrical functionalities

• Applicants: Professor Dr.-Ing. Jens Müller; Professor Dr.-Ing. Steffen Wiese
• Subject Area: Metallurgical, Thermal and Thermomechanical Treatment of Materials ; Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering ; Synthesis and Properties of Functional Materials ; Mechanical Properties of Metallic Materials and their Microstructural Origins ; Microsystems
• Term: since 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 426204742

In continuation of the previous project, the application of reactive multilayer systems (RMS) is being investigated in the field of microscale interconnections in electronics packaging. The focus is on the potential of using reactive multilayers to adjust a desired interconnection process via a predefined layer structure or morphology for joining partners with low or strongly differing thermal conductivities. While the vast majority of previous studies in the field of RMS bonding have always investigated the joining of Si with Si, metal with metal and Si with metal, the investigations in this project will be focused on the reactive bonding of two ceramic LTCC substrates or of silicon with LTCC substrates. The knowledge gained from the preliminary project that, in addition to the thermal conductivity, the surface roughness also has a decisive influence on the formation of the directly deposited reactive multilayer layers and subsequently on the reaction process is included in the investigations. Due to the partially unexpected findings obtained in the first phase of the project, the initial goals of the follow-up project will be more focused on developing a better understanding of the adhesion mechanisms for RMS bonding of thermally low conductive substrates such as the glass-ceramics used. A model is to be developed that describes the mutual relationships between boundary conditions (thermal conductivity, roughness, layer thicknesses, etc.) and process parameters (reaction rate and temperature) and their effect on the bond adhesion. On the experimental side, this is accompanied by the development of a novel in-situ test substrate that should allow direct temperature measurement during the reaction at the joint using thermocouples instead of embedded and isolated thermistors. In addition, the second phase aims at structured, localized RMS bonding, in contrast to previous experiments that used large, unstructured areas.

• DFG Programme: Research Grants