This paper explains die attach optimization technologies for silicon carbide (SiC) device packaging. High power density power module products are achieved by utilizing silicon carbide (SiC) chip owing to its excellent device properties with high temperature durability, low power conversion loss energy. Toward SiC chip packaging, new die attach technique bonded with high thermal conductivity substrate is required to remove high thermal flux generated around the small sized SiC chip. Especially, sintered silver (s-Ag) die bonding technique has attracted so many researchers owing to its high thermal conductivity, melting point, although low temperature bonding process condition. However, thermal shocked test (TST) has generally imposed as a practical operation reliability test that accompanies with thermal and mechanical stress degradation in the s-Ag die-attach area. After TST, die area shrinks, which makes thermal impedance worse compared to the initial state. Therefore, not only bonding s-Ag but also taking into material stress durability. s-Ag bonded with copper (Cu) substrate with 1mm, 2mm thick assemblies were performed through TST with -40 to 150℃ up to 1000 cycles. Die degradation evaluation was utilized by scanning acoustic tomography (SAT) images.

Pulsed laser irradiation and indentation tests on radiation shielding glasses with the different lead content and a lead-free glass were carried out. The size of irradiation damage of the glass with high lead content was larger than that with low content and the threshold of the damage initiation of the glass with high lead content was lower than that with low content. Constants in the material constitutive equation expressing the micro plastic behavior of glasses were quantitatively determined using the inverse analyses with Kalman’s filter and a finite element method based on indentation load-depth curves. Flow stress decreased with an increase of lead content and that in irradiated area was lower than that in unirradiated area. On the other hand, plastic flow resistance increased with an increase of the lead content and that in irradiated area was higher than that in unirradiated area. Fracture energy and critical size of plastic zone around tip of crack in unirradiated and irradiated areas were calculated based on experimental results including constants evaluated using the inverse analysis. These values decreased with an increase of the lead content and these values in irradiated area were lower than that in unirradiated area.

Thermal easy axis and thermal diffusivity of uniaxial carbon fiber-reinforced plastic sheets were determined by an offset periodic laser heating method, and investigated relationship between the thermal easy axis and fiber orientation with different thickness of CFRP sheet specimen, experimentally. It was clarified that the orientation of the thermal easy axis spreads in the in-plane direction with the sheet thickness deceases. Then, thermal diffusivity of CFRP specimens in the out-of-plane and in-plane direction were measured by two methods: a variable-frequency method and a variable displacement method, respectively. In the results of the out-of-plane directions, thermal diffusivity almost consistent with the carbon fiber direction were obtained. In contrast, the in-plane directions of those were exhibited unexpected value. Moreover, thermal diffusivity determination by offset periodic heating method was carried out. Finally, it is found that the thermal diffusivity considering the thermal easy axis with fiber angle was different characteristics from the in-plane direction measurement. These results are to be useful for development of a novel thermal interface materials with heat transfer controllable.

Thermophysical property data on molten Ni-based superalloys are almost non-existent. Hence, in this study, the viscosities of these superalloys were measured by the oscillating crucible method. The viscosities decreased with increasing temperature. When the logarithm of the viscosity was plotted against the inverse temperature (Arrhenius-type plot), all alloys showed good Arrhenius-type linearity over the temperature range investigated. These results agreed well with those of general pure metals and alloys from previous studies. Thus, the Arrhenius plot can approximate the viscosities of molten Ni-based superalloys. Moreover, the viscosities of the superalloys decreased with increasing Co content. In addition, the B value obtained in this study agreed well with that obtained by the viscosity relationship η = A∙exp(B/RT) and that for the liquidus temperature suggested by Hirai. Thus, the B value has a close relationship with the liquidus temperature.

Throughout the casting process, reducing casting defects called runaway defects is crucial. To reduce these defects, clarifying the filling behavior of the molten metals using casting simulations is required. The filling behavior arising from the casting simulation varies depending on various thermophysical properties; therefore, measuring the thermophysical properties with high accuracy is important. In this study, we clarified the effect of the viscosities of molten casting steels for high temperature by measuring them using the oscillating crucible method. The casting steels for high temperature samples used for the viscosity measurements contained 0, 10, 20, 30, 40, and 50 mass% Ni. Viscosities were evaluated using Roscoe's equation and measured in the temperature range of 1693–1803 K.

Directly measuring mechanical properties of freestanding films, such as electroplated films, is required for reliable mechanical design of devices. However, due to its technical difficulties, mechanical testing of thin films has been rarely conducted. In this paper, a high-throughput uniaxial tensile test technique and its technical issues for freestanding thin films are described. The combination of a lift-off-processed freestanding film and a micromachined Si frame enables us to carry out uniaxial tensile testing of a film material. An electroplated metallic film glued onto a Si substrate having a spring system is stretched in the axial direction. During the test, the distance between two gauge marks in the specimen’s parallel section is directly measured using a CCD image analysis system for tensile elongation measurement. The applied force is measured using a load cell. Uncertainty of force-displacement relationship is discussed from the aspect of an error related to specimen preparation and the image analysis system.

Al/Ni multilayers are attracting much attention as a local heat source for wafer bonding. However, after reactively bonding, cracks are introduced in reactively alloyed NiAl due to its brittleness and volume shrinkage. In this study, B contained Al/Ni multilayers are deposited by sputtering and the effect of B addition on mechanical characteristics and fracture of reactively alloyed NiAl film is investigated. 0.1wt% B is contained in alloyed NiAl compound after Bincluded Al/Ni film’s exothermic reaction. Cantilever bending testing is performed for investigating the Young’s modulus and fracture strength. Crack propagation testing is also performed to examine the effect of B containing on the fracture toughness. Transmission electron microscopy suggests that B segregation at the triple point of crystal grains is effective for crack propagation restriction on grain boundaries.

Long-term microtremor measurement was conducted for a composite structure. It is made clear that the natural period during construction gradually approaches its final value. We then presented a new regression formulation for the natural period of this composite structure, and compared it with the existing studies. It is therefore demonstrated that the natural period of the structure is quite different from the conventional composite structures, because of the higher stiffness of the substructure compared to standard steel structures.

Oil droplets in O/W emulsion are moved by external electric field. This transport of oil droplets is independent of surrounding water. The droplets are electrically charged by adding ionic surfactant in the O/W emulsion. Cationic and anionic surfactant respectively give positive and negative electric charges to the oil droplets. O/W emulsion with these charged oil droplets are placed in electric field between positive and negative electrodes. The charged oil droplets move towards electrode due to the Coulomb force. Positively and negatively charged droplets respectively moves negative and positive electrode direction. Velocity measurements of these droplets by PTV show the velocity increases with increase of voltage between electrodes. The velocity of the droplets keeps almost constant regardless of their diameter. The Coulomb force and the drag force affect the oil droplet may be balanced.