Laminated magnetic core

• US 5,097,373 A
• Filed: 08/02/1989
• Issued: 03/17/1992
• Est. Priority Date: 08/04/1988
• Status: Expired due to Fees

• Current Assignee: Nippon Light Metal Company Limited (Nippon Light Metal Holdings Co., Ltd.)
• Original Assignee: Nippon Mining & Metals Company Limited (JX Holdings Incorporated)
• Inventors: Yuki, Norio
• Primary Examiner(s): Heinz, A. J.
• Application Number:
  US07/388,519
• Time in Patent Office: 958 Days
• Field of Search: 360/126, 148/121, 148/120, 336/233
• US Class Current: 360/125.01
• CPC Class Codes: H01F 3/02 made from sheets
• CPC Class Codes: Y10T 156/1052 with cutting, punching, tearing or severing
• CPC Class Codes: Y10T 29/4902 Electromagnet, transformer or inductor
• CPC Class Codes: Y10T 428/24975 No layer or component greater than 5 mils thick

Abstract

There is disclosed a laminated magnetic core characterized in that core-forming thin sheets each having a surface roughness such that the maximum height Rmax is at least 1 μm are laminated together with a sheet-to-sheet distance of 2 to 10 μm, desirably 3 to 6 μm and that at least a part of protruded portions of the opposite roughed surfaces is diffusion-bonded to each other at the interface between adjacent thin sheets. The laminated magnetic core may have innumerable voids present at the diffusion-bonded interface between the adjacent thin sheets. This invention further provides a method of manufacturing a laminated magnetic core comprising the steps of providing a plurality of core-forming thin sheets each having a surface roughness such that the maximum height Rmax is at least 1 μm; laminating and bonding said core-forming thin sheets one upon another through an organic adhesive, desirably at a sheet-to-sheet distance of 2 to 10 μm; punching out a block of a given shape from said laminated and bonded core-forming sheets by a press; and thereafter magnetically annealing the block while decomposing and vaporizing said organic adhesive to effect diffusion-bonding at the interface between adjacent thin sheets of the block leaving innumerable voids at the interface.

Claims

1. A laminated magnetic core including a plurality of core-forming thin sheets each having protruded portions along both sides thereof defining a maximum height Rmax of at least 1 μ

m, wherein the thin sheets are laminated together to create an interface between adjacent sheets at a sheet-to-sheet distance of 2 to 10 μ

m and at least part of the protruded portions are diffusion-bonded to each other at the interface between adjacent thin sheets to create an insulating air gap therebetween.

2. The laminated magnetic core as described in the claim 1 wherein the sheet-to-sheet distance is 3 to 6 μ

m.

3. The laminated magnetic core as described in the claim 1 wherein innumberable voids are present at the diffusion-bonded interface between the adjacent thin sheets.