Bauteilschonende Verbindungstechnik auf Metallisierungen durch moduliertes Laserstrahlschweißen
Aachen / Apprimus Verlag (2017, 2018) [Book, Dissertation / PhD Thesis]
Page(s): 1 Online-Ressource (VIII, 143 Seiten) : Illustrationen, Diagramme
Due to the high demand in e-mobility and other high voltage applications, power electronic components are a key element in the focus of research and development. However, the increasing requirements of power electronic components represent a challenge for conventional interconnection processes due to the required high temperature stability and high reliability of the joint. Conventional soldering processes cannot be used for high temperature applications due to the low melting point of the solder and wire bonding processes are limited in the cross-section of the wire and in the material combination.Conventional laser welding is capable of a high control of energy deposition, but is not suitable for the welding of thick copper interconnectors to thin metallization, due to the resulting high overall energy input into the substrate. Ideally, an interconnection technology is required, which prevents temperature damage to the thermally sensitive substrate, ensures a sufficient mechanical strength and minimizes the electrical resistance of the joint.In order to weld thick copper interconnectors to thermally sensitive substrates, the novel approach “Laser Impulse Metal Bonding” (LIMBO) is investigated in this work. The LIMBO approach enables the welding of a copper interconnector over a gap to the metallization, which separates theprocess stages melting of the interconnector and joining to the metallization. The process is driven by the acceleration of the melt over the gap, which is achieved by temporal modulation of the laser beam.In the fundamental investigation of the LIMBO process, an analytical model of the melt deflectionis created, which is supported by thermal simulation and experimental studies regarding the vapor velocity. In the experimental part, three different modulation techniques are compared regarding the melt deflection and the energy deposition in the substrate.The LIMBO approach achieves an aspect ratio between the welding depth and the joining diameter of up to 1:45 and a process time below 100 ms. The thermal input into the substrate is minimized by a deflection and joining time below 5 ms. With these resulting characteristics of the LIMBO process, a novel packaging solution for e.g. printed-circuit boards, ceramic substrates (DCBs, DABs) and hybrid components (MIDs) is presented.