CFD Simulations of Reactive Multi-Layer Usage in Joining Processes

This paper discusses the application of the CFD methodology, with respect to the use of reactive multilayers as a joining technology for microelectronics. The simulation model represents a test assembly consisting of a $30 \mu \mathrm{m}$ thick reactive multilayer on the surface of a $570 \mu \mathrm{m}$ low temperature co-fired ceramic (LTCC) substrate, in order to study the interaction between the reactive multilayer and a typical substrate in electronics packaging. The CFD approach, implemented using ANSYS Fluent software, has the advantage of modelling the heat interchanges between fluid and solid structures with potentially interfering boundary conditions displaced further from the main areas of interest than in classical mechanical analyses. Furthermore, using ANSYS Fluent, one can model the latent heat and melting/solidification of the solder, which is crucial to revealing the true evolution of the joining process.