Patent ID: 8864929

Claim:
A method for manufacturing a laminated soft-magnetic sheet, the method comprising the following steps (A) to (D): (A) obtaining curable soft-magnetic sheets, each of the curable soft-magnetic sheets being produced by applying to a release base a soft-magnetic composition prepared by mixing at least a flat soft-magnetic powder, the flat soft-magnetic powder having an average particle size in the range of 10 to 50 μm, an aspect ratio in the range of from 15 to 60 , a tap density in the range of from 0.65 to 1.40 g/mL, and a specific surface area in the range of from 0.65 to 1.00 m 2 /g, an acrylic rubber having a glycidyl group, an epoxy resin, a latent curing agent for the epoxy resin, and a solvent, drying the applied soft-magnetic composition at a temperature T1 at which curing reaction of the soft-magnetic composition does not substantially take place, and removing the release base, wherein the amount of the flat soft-magnetic powder in the soft-magnetic composition except for the solvent is in the range of from 70 to 90 percent by weight, the amount of the acrylic rubber in the soft-magnetic composition except for the solvent is in the range of from 9 to 16 percent by weight, the amount of epoxy resin in the soft-magnetic composition except for the solvent is in the range of from 1.0 to 6.0 percent by weight, the amount of the latent curing agent for the epoxy resin is in the range of from 3 to 100 parts by weight with respect to 100 parts by weight of the epoxy resin, and the temperature T1 is in the range of from 50 to 90 ° C.; (B) obtaining a laminate of the curable soft-magnetic sheets by laminating at least two of the curable soft-magnetic sheets; (C) compressing the obtained laminate at a temperature T2 at which the curing reaction does not substantially take place, using a laminator for applying a linear pressure thereon while the linear pressure is sequentially changed from a linear pressure P1 , to a linear pressure P2, and to a linear pressure P3 (wherein P1 <P2 <P3 ), wherein the temperature T2 is in the range of from 70 to 130 ° C., the linear pressure P1 is in the range of from 2 to 10 kgf/cm, the linear pressure P2 is in the range of from 10 to 20 kgf/cm, and the linear pressure P3 is in the range of from 20 to 50 kgf/cm; and (D) after step (C), obtaining a laminated soft-magnetic sheet by compressing the compressed laminate at a temperature T3 at which the curing reaction takes place, using a press for applying surface pressure thereon, wherein the temperature T3 is in the range of from 140 to 200 ° C., and the surface pressure is in the range of from 10 to 60 kgf/cm 2 , and each of the curable soft magnetic sheets in the compressed laminate are in direct contact with each adjacent curable soft magnetic sheet.