Browse Prior Art Database

Laminated Structures

IP.com Disclosure Number: IPCOM000091006D
Original Publication Date: 1969-Sep-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Brock, GW: AUTHOR [+2]

Abstract

Normally, laminae of magnetically permeable metallic materials, such as permalloy and HyMu 80, are bonded together adhesively to form laminated structures. The resulting laminated structures are used, for example, in transformers, motors, generators, and magnetic read and write heads. In all these applications, good magnetic permeability is desired. High permeability is especially desirable in magnetic heads where optimization of magnetic coupling with the magnetic record media is required. However, conventional adhesive bonding of laminae, for example, with epoxy, results in stresses upon the laminae which can significantly alter the magnetic permeability of the structure. Stresses are caused by shrinkage of the adhesive as it is cured.

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Laminated Structures

Normally, laminae of magnetically permeable metallic materials, such as permalloy and HyMu 80, are bonded together adhesively to form laminated structures. The resulting laminated structures are used, for example, in transformers, motors, generators, and magnetic read and write heads. In all these applications, good magnetic permeability is desired. High permeability is especially desirable in magnetic heads where optimization of magnetic coupling with the magnetic record media is required. However, conventional adhesive bonding of laminae, for example, with epoxy, results in stresses upon the laminae which can significantly alter the magnetic permeability of the structure. Stresses are caused by shrinkage of the adhesive as it is cured. Excessive eddy current losses are also experienced within the laminated structure where the adhesive is discontinuous so that there are points of intimate electrical contact between the laminae.

Stress relief and continuous electrical insulation between laminae is provided by oxidizing the surfaces of the laminae prior to adhesive bonding. The drawing shows the permeability-frequency characteristics of adhesively-bonded laminated structures made in a conventional manner 2 and structures made with oxidation of the laminae prior to bonding 4. The conventional laminated structure is prepared from torroidal laminae of 4-79 Molybdenum permalloy, 1 mil thick, which are annealed in a hydrogen furnace. The laminae are then coated with uncured epoxy adhesive, stacked, and placed in a flattening fixture to remove their slight degree of curvature due to their...