Batch Processed Linear Array Heads for Close-Packed Track Recording

This paper describes a novel design concept and experimental hardware data of array heads for close-packed track recording. The heads are batch fabricated on wafers in a linear fashion. These 60-turn thin-film inductive heads are designed with 6-um pitch helical coils and planar side-by-side P1/G/P2 yokes structre. The linear head array is placed along the upstream-to-downstream diretion of the track. By skewing the array slightly off the track direction, each head of the array aligns to an individual track. In this case, the track pitch is about 5 um, which is the yoke height. With this head arrangment, even though thermal expansion causes the head-to-head distance to increase along the upstream-downstream direction, it does not cause thermal induced track mis-registration problem. The increased head-to-head distance only affects the timing of signals between tracks, which can be compensated by the channel electronics. Thus, the thermal induced track mis-registration problem is eliminated using this design. The guardbands between tracks are not necessary and a close-packed track recording is possible. A state of the art head impedance of the 60-turn head is obtained: 11 Omega and 0.40 uH. The gap-to-gap pitch is 100 um. The overall head-to-head isolation is greater than 50d B at 10MHz. Such a large isolation is realized by suppressing the capacitive coupling between lead wires using a ground plane and grounded wall structures. The tight winding of the helical coils reduces the magnetic coupling between the heads.