Thermal conductivities of Ni-Cr solid solution alloys have been measured to develop a prediction equation for thermal conductivities as functions of temperature and chemical composition. Samples used were Ni-x at% Cr (0 ≤ x ≤ 22) and commercial alloys of Nichrome Nos. 1 and 2. Thermal conductivity measurements were carried out using the transient hot-strip method over a temperature range from 293 K to 1273 K. The thermal conductivities of the alloys increased with increasing temperature and decreased with increasing Cr concentration at constant temperature. The Smith-Palmer equation has been examined to relate the thermal conductivities of the alloys to the electrical resistivities. The thermal conductivity and electrical-resistivity data, respectively, in the present work and in the literature have confirmed that the Smith-Palmer equation applies to Ni-Cr solid solutions and Nichrome alloys. On the basis of this equation, the thermal conductivity of Ni-Cr solid solution alloys has been expressed as a function of temperature and chemical composition. This analysis has also been applied to Ni-Fe and Cu-Ni solid solution alloys.

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The non stationary, hot wire method has been developed for use with an insulated, coated probe in order to determine thermal conductivities of metals. This development was carried out using both simulation and experimentation. The simulations of the temperature increase ( DT ) of the heater were carried out using various solid samples (Al, V, Ag and W). Experiments were carried out using hot strip and hot wire probes to determine DT from the voltage change ( DV ) using the four terminal method. Measurements of DT on solid Fe, Ni and Ti were made using hot strip probes with coatings of (i) silica (ca. 5 mm thickness) and (ii) mica (20 300 mm thickness). Similarly, experiments were carried out on liquid Hg and Ga using hot wire probes with coatings of (i) silica (ca. 5 mm thickness) and (ii) alumina based material (170 470 mm thickness). The results of simulations and experiments have shown:(1) The following equation applies to dDV/d ln t (t: time) obtained using an identical probe: dDV/d ln t＝A(I 3 ･a T ･R 273 ･X T /4p)･(1/l)＋B where dDV/d ln t is an average slope for the time period 1 2 s, l is the thermal conductivity at a certain temperature (T ), I is the current supplied to the heater, a T is the temperature coefficient of electric resistivity of the heater at T K, R 273 is the resistance between the potential leads for the four terminal method of the heater at 273 K, X T is the resistance per unit length of the heater at T K, and A and B are probe constants.(2) The probe constants are independent of temperature. Thus equations for other temperatures (T 1 ) can be obtained by replacing temperature dependent terms a T and X T in the above equation by those for T 1 as follows: dDV/d ln t＝A(I 3 ･a T1 ･R 273 ･X T1 /4p)･(1/l)＋B Using these relations, the thermal conductivity of liquid Ga was determined over the temperature range (310 500 K). It has also been found that determination of the thermal conductivity is unaŠected by coating thickness providing that the thickness of the insulating layer is ＜ca. 300 mm.

As the demand for advanced packaging is growing, the value of mid-end process technologies is increasing in an effort to realize innovative device products. Substrate-free packaging and 3D integration are coming with the challenges to polymer resin deposition for interlayer dielectrics films and final passivation films and their developments of process integration. For cost reduction of Fan-out Wafer Level Packaging, we have demonstrated thick film deposition on square panel substrates using the photo-sensitive resin materials tailored to spray-coating and slit-coating. Chip stacking of a high performance logic chip on a high band-width DRAM needs fine pitch patterning of a thick photo-resist for Cu electroplated redistribution lines on the DRAM. Our successful process integration has confirmed that slight oxidation of the Cu seed surface to form Cu 2 O is preferred to improve adhesion between the resist and the Cu surface. Finally, the restoration of plasma damaged surface of a polymer final passivation film on advanced low-k chips to improve reliability of flip chip packages has been discussed as one of typical examples of materials design for process integration.

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