Thin-film inductive head

Metal in gap (MIG) or ferrite heads are produced with a combination of machining, bonding, and thin-film processes. Thin-film inductive heads are manufactured using thin-fihn processes similar those of semiconductor 1C technology (discussed in Chapter 19). The thin-film head production process is rather unusual, as it involves both very thin and very thick films. We choose to present here a detailed summary of the fabrication process of thin-film inductive heads with a single-layer spiral coil. This may serve, once again to, illustrate the centrally important role of electrochemical deposition in connection with modem information technology. 

Most thin-film inductive heads employ multilayer spiral coils to achieve large read back signals. This means that the copper plating and the hard cured photoresist steps must be repeated. Electrical coimection between the neighboring coil layers must also be implemented. Naturally, these steps greatly add to the complexity of the thin film head production. 

Thin-film inductive heads may be used for reading processes also. When used in the reading process, read heads intercept the magnetic field from the recorded magnetization pattern in magnetic recording medium and convert it into electrical signals, which are then detected and decoded. 

The structure of thin-film inductive recording heads results in the exposure to the environment of small areas of metal, often permalloy (Ni-20Fe), which is a relatively corrosion-resistant alloy. In fact, in-service corrosion of permalloy is not a problem and thin-film inductive heads have no history of corrosion-induced field failure. However, corrosion of permalloy can occur during manufacturing, leading to yield losses. 

Most (thin-film) inductive magnetic heads have a magnetic core and coil fabricated by electrodeposition using... 

FIGURE 2 Fabrication of heads for HDDs, (a) Thin film inductive and GMR heads are batch fabricated on ceramic wafers, (b) Wafers are sliced into rows. At the row level, the air bearing surface is first lapped to tight flatness specifications, and then lithographically patterned and etched to create air bearing features. Air bearing features are typically 0.1-2 om in height, (c) Finally, rows are parted into individual sliders 1 x 1.25 x 0.3 mm in size. SOURCE IBM. 

The structure of thin-film inductive recording heads results in the exposure to the environment of small areas of metal, often permalloy (Ni-20Fe), which is a relatively... 

Tsang C et al (1990) Gigabit density recording using dual-element MR inductive heads on thin-film disks. IEEE Trans Magn MAG-26 1689-1693... 

Magnetic read/write elements have evolved from wire-wound ferrite inductive heads to microfabricated thin-film structures. Today, separate read and write elements are used, with a thin-fihn inductive element for writing and magnetoresistive element for reading. The quest for ever-increasing read head sensi-... 

The critical metallic components of advanced magnetic and magneto-optic (MO) storage devices— thin-film metal disks, inductive or magnetoresistive heads, and MO layers—are all susceptible to corrosion and each has been a subject of considerable study. Several review articles covering corrosion of magnetic-storage media may be found in the literature [135,136]. 

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