17 research outputs found
Approaches in Sustainable, Biobased Multilayer Packaging Solutions
The depletion of fossil resources and the growing demand for plastic waste reduction has put industries and academic researchers under pressure to develop increasingly sustainable packaging solutions that are both functional and circularly designed. In this review, we provide an overview of the fundamentals and recent advances in biobased packaging materials, including new materials and techniques for their modification as well as their end-of-life scenarios. We also discuss the composition and modification of biobased films and multilayer structures, with particular attention to readily available drop-in solutions, as well as coating techniques. Moreover, we discuss end-of-life factors, including sorting systems, detection methods, composting options, and recycling and upcycling possibilities. Finally, regulatory aspects are pointed out for each application scenario and end-of-life option. Moreover, we discuss the human factor in terms of consumer perception and acceptance of upcycling
Wafer-level SLID bonding for MEMS encapsulation
Hermetic packaging is often an essential requirement to enable proper functionality throughout the device's lifetime and ensure the optimal performance of a micro electronic mechanical system (MEMS) device. Solid-liquid interdiffusion (SLID) bonding is a novel and attractive way to encapsulate MEMS devices at a wafer level. SLID bonding utilizes a low-melting-point metal to reduce the bonding process temperature; and metallic seal rings take out less of the valuable surface area and have a lower gas permeability compared to polymer or glass-based sealing materials. In addition, ductile metals can adopt mechanical and thermo-mechanical stresses during their service lifetime, which improves their reliability. In this study, the principles of Au-Sn and Cu-Sn SLID bonding are presented, which are meant to be used for wafer-level hermetic sealing of MEMS resonators. Seal rings in 15.24 cm silicon wafers were bonded at a width of 60 µm, electroplated, and used with Au-Sn and Cu-Sn layer structures. The wafer bonding temperature varied between 300 °C and 350 °C, and the bonding force was 3.5 kN under the ambient pressure, that is, it was less than 0.1 Pa. A shear test was used to compare the mechanical properties of the interconnections between both material systems. In addition, important factors pertaining to bond ring design are discussed according to their effects on the failure mechanisms. The results show that the design of metal structures can significantly affect the reliability of bond rings
Microstructural evolution of Cu–Sn–Ni compounds in full intermetallic micro-joint and in situ micro-bending test
This is a post-peer-review, pre-copyedit version of an article published in Journal of Materials Science: Materials in Electronics. The final authenticated version is available online at: https://doi.org/10.1007/s10854-018-9293-8This study focuses on the microstructural evolution process of Cu–Sn–Ni intermetallic compounds (IMCs) interlayer in the
micro-joints, formed from the initial Ni/Sn (1.5 µm)/Cu structure through transient liquid phase (TLP) soldering. Under the
bonding temperature of 240 °C, the micro-joints evolve into Ni/(Cu, Ni)6Sn5/(Cu, Ni)3Sn/Cu structure, where the interfacial
reactions on Cu/Sn and Sn/Ni are suppressed by the atoms diffusing from the opposite side. The thickness of (Cu, Ni)3Sn
layer on plated Cu layer still increases with the prolonged dwell time. When the bonding temperature was elevated to 290 °C,
the phase transformation of (Cu, Ni)6Sn5 into (Cu, Ni)3Sn has been accelerated, thus the majority of IMCs interlayer is
constituted with (Cu, Ni)3Sn. However, a small amount of Ni-rich (Cu, Ni)6Sn5 phases still remain near the Ni substrate and
some of them close to the center-line of IMCs interlayer. The state between (Cu, Ni)6Sn5 and the adjacent (Cu, Ni)3Sn tends
to reach equilibrium in Ni content based on the observation from Transmission Electron Microscope (TEM). In addition,
the Cu–Sn–Ni IMCs micro-cantilevers were fabricated from these micro-joints using Focus Ion Beam (FIB) for the in situ
micro-bending test, the results indicate a high ultimate tensile strength as well as the brittle fracture in the inter- and transgranular modes