Browse Prior Art Database

Batch Fabrication of Keyhole Type Magnetic Recording Heads

IP.com Disclosure Number: IPCOM000083278D
Original Publication Date: 1975-Apr-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 3 page(s) / 66K

Publishing Venue

IBM

Related People

Romankiw, LT: AUTHOR [+2]

Abstract

A technique is described for batch fabrication of approximately 2 mil thick laminated structures with a keyhole pattern (see Fig. 1) electroformed around photoresist. It is possible to electroform 0.05 to 0.2 mil wide slots in 5 to 6 micrometers of permalloy by forming the photoresist pattern of keyhole head configurations, and by subsequently electroplating permalloy in a sheet form around the pattern.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 47% of the total text.

Page 1 of 3

Batch Fabrication of Keyhole Type Magnetic Recording Heads

A technique is described for batch fabrication of approximately 2 mil thick laminated structures with a keyhole pattern (see Fig. 1) electroformed around photoresist. It is possible to electroform 0.05 to 0.2 mil wide slots in 5 to 6 micrometers of permalloy by forming the photoresist pattern of keyhole head configurations, and by subsequently electroplating permalloy in a sheet form around the pattern.

A further build-up of the sandwich up to 2 mils is accomplished by repeated applications of photoresist and exposure of the keyhole pattern, after each 5 to 6 microns thick layer of permalloy is plated (see Fig. 3). Nonmagnetic layers such as Cu, Rh, Au, SiO(2) or glass, or any other metal or insulator of any desired and well controlled thickness, can be deposited by electroplating (electroforming), electrodeless plating, chemical deposition, evaporation or sputtering between each layer of permalloy to provide the desired magnetic sandwich structure. Since all magnetic and nonmagnetic layers can be electroformed using the same photoresist mask, the holes in the structure will be in perfect alignment. Each sandwich is electroformed after an application, exposure and development of photoresist. A total of 6 to 8 layers may be necessary to form the 2 mil thick lamination.

The same glass mask is used to expose the resist pattern for each of the subsequent layers. A perfect alignment of the keyhole shape from layer-to-layer results. Registration is limited only by the registration tolerance of the mask with the identical pattern underneath. This registration may be held to within +/- 0.01 mil by conventional lithographic technique. If better registration is desired, the same electroforming process can be used in connection with an electron-beam resist. Advantages of this technique are as follows: (1) Batch fabrication of large numbers of heads at a single time. (2) Optimum control of thicknesses of the magnetic and nonmagnetic layers. (3) Elimination of mechanical alignment and handling. (4) Elimination of lamination by glueing or diffusion bonding of the layers. (5) Substantial elimination of the difficult step of etching of the 0.1 nil wide slots in 0.5 mil thick metal sheets. (6) Optimum registration of the slots in all layers of the sandwich structure. (7) Ease with which the photoresist can be removed from the keyhole keyhole after the fabrication is completed. (8) Thin lamination layers of the magnetic film minimize eddy current damping. (9) Gaps of <5 mu dimension can be formed with the quality of permalloy and ease of fabrication improving as the gap decreases, i.e.. from 10 mu down to 2 mu. Details of the Technique A.) Details of the fabrication process The substrates on which the heads can be deposited include:

1.) Steel mandrel plated with copper or other stiffeners, such as metals which can be selectively etched without attacking permalloy (see Fig. 1).

2.) Inorganic...