Selected characteristics of plated wires from various sources

Plated wires, 2.5 and 5.0 mils in diameter, have been obtained from various sources and compared to our own 2.5 mil diameter wire made on both copper-beryllium and tungsten substrates. The wires have been tested for their digit, word, and shmoo windows, pulse output and uniformity of output, skew and magnetostriction and their uniformity, the tension and torsion stress changes in the above characteristics, the thickness of the magnetic layer, stability during accelerated aging, and their mechanical characteristics. The characteristics of the wires in the unstressed condition were all adequate for memory application. Differences in signal output and location of the operating windows could be correlated with differences in film thickness and wire diameter. Pulse signal fluctuations were found to be directly proportional to magnetostriction fluctuations. There were great differences observed in the behavior of the samples under stressed conditions. These differences were shown to arise from differences in the local fluctuations in magnetostriction, the modulus and diameter of the substrate, and differences in the metallurgical and magnetic structure of the permalloy film. Accelerated aging showed 2:1 differences in rate between some samples.