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The possibility of electrodeposition of soft gold from a thiosulf ate-sulfite bath was explored for electronics applications. The bath does not contain cyanide, and it is operated at a near neutral pH and a mildly elevated temperature. The bath is stable, does not undergo spontaneous decomposition without the addition of any stabilizer, and yields gold deposits with a hardness sufficiently low for use as gold bumps on semiconductor devices. Factors affecting the hardness were investigated in detail. It is shown that the use of high concentrations of the complexing agents and/or the addition of thallium(I) ions decreases both hardness and sulfur content of the deposit. The lowest Vickers hardness values achieved were approximately 80 kg mm2 in the as-deposited state and 50 kg mm2 after annealing at 350°C for 30 mm in air. The relationship between hardness and microstructure of the deposit was also examined.* Electrochemical Society Active Member.

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in the films that are sufficiently small that migration of ion pairs involving the smaller tetramethylammonium ion is hindered very little but that migration of ion pairs involving the larger tetrabutylammonium ion is hindered greatly.4. This ion-pair catalysis was found to occur even in experiments in which codeposition of insoluble basic zinc salts occurred.

A soft magnetic CoNiFeS film as a write head core material for the next generation was prepared by electrodeposition. In this system, thiourea was used as an additive in the CoNiFe ternary alloy plating bath. The most suitable magnetic properties were obtained at the film composition of (Co73Ni12Fe15)991S59 [atomic percent (a/o)1 with a high saturation magnetic flux density (B,) of 1 .7 T, a high resistivity (p) of 51 pS cm, and a low saturation magnetostriction (X,) of 4.4 x 10-6. The film consisted of fine minute crystal grains 5 to 10 nm in diameter. The S content of Ca. 0.9 aio is believed to be responsible for the formation of small crystal grains with low coercivity and high resistivity.