Michihiko Inaba

Solder bumper formation using electroless plating and ultrasonic soldering

Aluminum electrodes in the Si wafer were surface-treated in the sequence palladium activation, Ni-P electroless plating, ultrasonic soldering with Pb-1Sn solder, and dipping in Sn-37Pb to form second-stage solder bumps. The average bump height and the shear force were 20.3 mu m and 26.8 g/pad, respectively. The shear force did not decrease after the heating test (150 degrees C*1000 h) or thermal cycle test (-65 degrees C (--) room temperature (--) 150 degrees C, 300 cycles). Aluminum diffused to amorphous Ni-P through the Pd layer, Ni-Sn intermetallic compounds were formed at the Pb-1 Sn/Ni-P interface. The low-cost polyester tape-automated bonding was utilized to melt low temperature second solder on inner lead bonding. No bridge occurred when applying this technique to an LSI device with 376 electrodes, 100 mu m wide with 150 mu m pitch.<<ETX>>

Development of an Invar (Fe-36Ni) shadow mask for color cathode ray tubes

An Invar shadow mask was developed for color television tubes. Crystal faces on the rolled material surface are concentrically

Effects of the annealing conditions on the oxidation behavior of Fe-36Ni alloys

Invar alloys with typical composition Fe-36%Ni were oxidized in air at temperatures of 823–1073 K with changing annealing conditions prior to the oxidation test, i.e. in vacuum annealing (10-2 Torr) and in hydrogen annealing (dew point = 293 K). The oxidation behavior of these alloys is evaluated by observing impurity segregation, dislocation density and oxide film composition. The results obtained are as follows: (1) The growth rate of the oxide film (α− Fe2O3NixFe3−xO4, 0<x<3) was found to follow parabolic law. It was two to three times higher on the hydrogen annealed samples than on the vacuum annealed samples. (2) The hydrogen annealed samples were found to have a high density of dislocations on their surfaces and no segregation of silicon, chromium or other impurities was found thereon. In the low temperature range used in this experiment, the oxide growth tended to depend on the density of dislocations in an inner oxide layer.

Solder bump formation using electroless plating and ultrasonic soldering

Aluminum electrodes in the Si wafer were surface-treated in the sequence palladium activation, Ni-P electroless plating, ultrasonic soldering with Pb-1Sn solder, and dipping in Sn-37Pb to form second-stage solder bumps. The average bump height and the shear force were 20.3 mu m and 26.8 g/pad, respectively. The shear force did not decrease after the heating test (150 degrees C*1000 h) or thermal cycle test (-65 degrees C (--) room temperature (--) 150 degrees C, 300 cycles). Aluminum diffused to amorphous Ni-P through the Pd layer, Ni-Sn intermetallic compounds were formed at the Pb-1 Sn/Ni-P interface. The low-cost polyester tape-automated bonding was utilized to melt low temperature second solder on inner lead bonding. No bridge occurred when applying this technique to an LSI device with 376 electrodes, 100 mu m wide with 150 mu m pitch. >

Effects of trace impurities on the adherence of oxide to ultra low carbon steel

The effects of trace impurities on the adherence of oxides to ultra low carbon steels were investigated. Three steels, of differing chromium, aluminium, silicon, nitrogen and oxygen content, were oxidized at 850 K in 10% CO2-90% N2 gas and then oxidized at 770 K in 10% CO2-10% O2-80% N2 gas. Surface analysers, i.e. a Mössbauer spectrometer, Auger electron spectrometer and/or ion micro analyser, were utilized in the present study because of the very thin layer of oxides formed (1.0 to 2.0 µm). The following results were obtained. The oxide on the Al-containing steel spalled at the outer-inner oxide interface, where aluminium was enriched and many cavities appeared. The inner oxide layer, oxidized by the transport of CO2 or O2 gases along the outer layer grain boundaries or micropores, became thick. This generated a stress at the outer-inner layer interface with the resultant formation of cavities. On the other hand, the oxide on the Cr-containing steel showed good adherence to the metal. The inner layer, enriched with chromium, did not become thick and had no cavities at the interface. The addition of chromium to the Al-containing steel resulted in good oxide adherence because chromium acted as a barrier to the aluminium enrichment.

Characteristics of chromium-added Invar with regard to shadow masks for high-resolution colour television tubes

Abstract The characteristics of chromium-added Invar for use in shadow masks were studied, and the following advantages found for this metal. (1) The yield strength of the alloy decreases with increased added chromium, up to 5 wt%, on annealing, resulting in good formability. (2) The crystal orientation was textured to the {100} plane by hard cold rolling and annealing to allow easy etching. (3) The adherence of oxide to metal is better than that on Invar. (4) Magnetic properties caused no problem for use as a shadow mask.

Mechanical properties of Fe-36 Ni base alloys with chromium addition up to 5 mass%

Mechanical properties, such as yield strength (σ0.2), tensile strength (σb), elongation (δI), strain-hardening coefficient (n) and modulus of elasticity (E), for chromium added Fe-36 mass% Ni with chromium addition of up to 5 mass% were studied as a function of annealing temperature from 1053 to 1423 K in a dry hydrogen atmosphere. When chromium was added to Fe-36 Ni, σ0.2 decreased, butn andE increased. σB and δI scarcely changed with the chromium addition. σ0.2, σB, δI andE decreased with the increase in annealing temperature. The relation between σ0.2 and grain size was in agreement with Petchs equation.