Intermetallic Bonding for High-Temperature Microelectronics and Microsystems: Solid-Liquid Interdiffusion Bonding

Solid-liquid interdiffusion (SLID) bonding for microelectronics and microsystems is a bonding technique relying on intermetallics. The high-melting temperature of intermetallics allows for system operation at far higher temperatures than what solder-bonded systems can do, while still using similar process temperatures as in common solder processes. Additional benefits of SLID bonding are possibilities of fine-pitch bonding, as well as thin-layer metallurgical bonding. Our group has worked on a number of SLID metal systems. We have optimized wafer-level Cu-Sn SLID bonding to become an industrially feasible process, and we have verified the reliability of Au-Sn SLID bonding in a thermally mismatched system, as well as determined the actual phases present in an Au-Sn SLID bond. We have demonstrated SLID bonding for very high temperatures (Ni-Sn, having intermetallics with melting points up to 1280°C), as well as SLID with low process temperatures (Au-In, processed at 180°C, and Au-In-Bi, processed at 90–115°C). We have verified experimentally the high-temperature stability for our systems, with quantified strength at temperatures up to 300°C for three of the systems: Cu-Sn, Au-Sn and Au-In

Thermal management of an interventional medical device with double layer encapsulation

This paper presents a thermal study of a double-layer encapsulation for an interventional medical device, which operates temporarily inside the human esophagus for cardiac imaging. The surface temperature of test samples, representing the device, was assessed by experiments and numerical simulations. The test samples consisted of a heat source, a heat sink and a double-layer encapsulation consisting of a 3D printed biocompatible polymer (thickness 0.9 mm), with an electroplated Cu inner layer (0, 10, 80 or 150 µm thick). The surface temperature of test samples was measured in a tissue-mimicking thermal phantom at 37°C, with different heat source power levels. Experimental results showed that the maximum steady-state surface temperature could be reduced significantly by a 10 µm thick Cu layer (compared to no Cu layer). Increasing the Cu layer thickness further had a rather small effect, at least for low power levels. The maximum steady-state surface temperature was an exponential function of the Cu layer thickness. Test samples with a Cu electroplated polymer encapsulation and a heat source power of 0.5 W satisfied the maximum temperature limit for thermal safety (43°C) when the Cu layer was thicker than about 80 µm. Simulated surface temperatures were in good agreement with experimental values, for a model using two different thermal contact conductance coefficients (for different materials) for the sample-phantom boundary condition. The simulation model was also used to suggest alternative materials for the outer layer of an encapsulation with a metal inner layer, for reducing the surface temperature.publishedVersio

Characterization of Cu-Sn SLID interconnects for harsh environment applications

This paper reports on the results obtained from performing 'shake and bake' testing on demonstrator vehicles bonded using Cu-Sn SLID technique. The demonstrator vehicles were exposed concurrently to vibration and thermal loadings similar to those seen in aerospace and downhole applications. This work demonstrates that Cu-Sn SLID bonding process is ideal for packaging sensors and electronics to be used within harsh environments, especially those encountered in the aerospace and oil & gas industries

Kystskogbrukets gryande potensial : logistikk og driftsteknikk i bratt terreng i Ørsta

Logistikk- og driftsplan for seks veglause område i Ørsta kommune. Desse seks områda er ein del av resultatet etter skogreisinga i kystskogbruket, og for å hauste desse ressursane må ein ha realistiske tilnærmingar til vegplanlegging og driftsmetodikk

The coastal forestry's upcoming potential : road network and harvesting methods in steep terrain in Ørsta

Logistikk- og driftsplan for seks veglause område i Ørsta kommune. Desse seks områda er ein del av resultatet etter skogreisinga i kystskogbruket, og for å hauste desse ressursane må ein ha realistiske tilnærmingar til vegplanlegging og driftsmetodikk.Ørstaskogprosjekte