High Density Assembly

Assembly and interconnect technology has to meet different requirements from microelectronics, MEMS, photonics, RF and power electronics and deals accordingly with Si, SiC, GaN, GaAs, InP, Ge and other semiconductor materials. Reflow soldering, transient liquid phase bonding (TLPB), thermocompression and thermosonic bonding are the favored interconnection methods for flip chip attach.

Assembly and interconnection technologies applied to 3D systems are strongly affected by IC technology nodes. Key parameters include die size, number of I/O, pad geometries, passivation layers, wafer-surface topologies, terminal pads and limitations to the thermal budgets that can be applied during assembly. Additional challenges in assembly and interconnect technologies for 3D systems include alignment accuracy, yield requirements and productivity that meet the demands of cost effective manufacturing.

Furthermore, WLSI has broad experience in fluxless assembly methods for photonics and MEMS as well as in hermetical sealing. Precision bonding with an alignment accuracy of 1 µm will be achieved for photonic applications using either thermode bonding with high positioning accuracy or with solder-assisted self-alignment methods – with or without mechanical stops.




Focus of research

  • 3D IC assembly with high-density interconnects (> 1000 I/O) and ultra-fine pitch (> 25 μm)
  • IC assembly with thin and ultra-thin chips (>50 μm)
  • Solder assisted self-alignment with and without mechanical stops
  • Precision bonding
  • Transient liquid phase bonding
  • Thermocompression & thermosonic bonding Cu-Cu, Au-Au, In
  • Hybrid bonding technologies
  • Assembly of ultra-small chips & collective bonding approaches




R&D services

With in this research field, the department WLSI offers a broad spectrum of services. For specific questions do not hesitate to contact us.

Projects in this research area


Gold TSV Technology



μ-structured luminous diodes for innovative adaptive headlights