Western Digital AMR and GMR Heads Increase Hard Drive Capacity in Drives free download

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AMR and GMR Heads Increase Hard Drive Capacity in Western Digital Drives Anisotropic Magnetoresistive and Giant Magnetoresistive Head Technology Taking Over Hard Drives OVERVIEW/EXECUTIVE SUMMARY Error rate, the number of data bits correctly decoded by the recording head and fly height, the distance between the read/write elements of the head and the magnetic layer of the media are key design parameters in the quest for higher areal density. Designers strive to keep error rate and fly height as large as possible. Error rate for performance reasons and fly height for reliability. For a given head technology, however, these are mutually exclusive goals. To achieve higher areal densities with thin film inductive (TFI) heads, fly heights had to decrease in order to maintain acceptable error rates. Increasing the ability of the head to detect magnetic signals (i.e. head sensitivity) and slow the rate at which fly height decreased was possible for a time. Eventually, new technologies were needed. Hence the development and introduction of Magneto-Resistive (MR), both anisotropic and giant magnetoresistive, technology. See Figure 1 for a comparison of anisotropic MR and giant MR technologies. Anisotropic Magnetoresistive (AMR) head technology is currently the primary read/write head technology used in hard drives, replacing TFI heads, the previous standard in the marketplace. GMR heads will be the dominant head technology by the end of 1999. Western Digital is incorporating AMR heads from IBM, Read-Rite and others as well as GMR heads from IBM in desktop drives today. GMR heads from other suppliers will be making their way into drives in the second half of 1999. AMR vs GMR Error Rate / Yield Comparison 4.0 3.5 % Error Rate > 1E-5 3.0 AMR 2.5 2.0 1.5 GMR Wr = 0.95