Composite magnetic recording disk

Abstract

A composite structure for magnetic recording includes a core member of polymeric material to which is bonded at least one silicon disk having a magnetic recording material on its outer surface. The silicon disk surface provides optimal flatness and smoothness characteristics for a magnetic recording substrate, while the polymeric core member provides strength to the structure.

We claim: 
     
       1. A substrate for a magnetic recording disk structure, comprising, a rigid silicon disk having a thickness no greater than 0.025 inches,   an annular shaped core member formed of a polymeric material, said polymeric material having high rigidity and tensile strength and low elongation, bonding means for bonding one surface of said silicon disk to said core member,   the other surface of said silicon disk being adapted to receive a magnetic recording material to form a magnetic recording member.   
     
     
       2. Apparatus in accordance with claim 1, in which said polymeric material contains a fiber reinforcement material. 
     
     
       3. Apparatus in accordance with claim 1, in which said core member has an annular recess therein to receive said silicon disk, the walls of said recess serving to protect the relatively fragile silicon disk. 
     
     
       4. Apparatus in accordance with claim 1, in which said structure includes two of said silicon disks bonded to opposite sides of said core member, the outer surfaces of each of said disks being adapted to receive a magnetic recording material thereon. 
     
     
       5. Apparatus in accordance with claim 4, in which said core member has annular recesses on opposite surfaces to receive said silicon disks, the walls of said recesses serving to protect the relatively fragile silicon disks. 
     
     
       6. Apparatus in accordance with claim .[.7.]. .Iadd.5.Iaddend., in which said walls of said recesses extend above the surfaces of said disks. 
     
     
       7. Apparatus in accordance with claim .[.8.]. .Iadd.6.Iaddend., including a plurality of such structures clamped together, the extending walls of said recesses forming load bearing surfaces for adjacent structures and providing space between adjacent surfaces for access thereto by magnetic transducing means. .Iadd. 
     
     
       8.  A composite magnetic recording disk comprising a substrate consisting essentially of a relatively thin wafer of crystal grown semiconductor grade silicon having a smooth, flat surface,   a layer of magnetic recording material on said surface onto which magnetic indicia may be written and from which it may be read during rotation of the disk, and   a reinforcing support member contacting a surface of the substrate remote from said flat surface for rotation with the substrate as a unitary structure, thereby to insure that the substrate will withstand the forces generated during rotation of the disk. .Iaddend. .Iadd.9. A composite magnetic recording disk according to claim 8, characterized in that said member has a thermal coefficient of expansion matched to that of the silicon substrate. .Iaddend. .Iadd.10. A composite magnetic recording disk according to claim 8, characterized in that said member is formed of a material having high tensile strength and low elongation for withstanding forces at high rotational speeds and high rigidity for impact resistance. .Iaddend. .Iadd.11. A composite magnetic recording disk according to claim 8, characterized in that said substrate is cut from a silicon boule. .Iaddend. .Iadd.12. A composite magnetic recording disk according to claim 8, characterized in that said substrate is cut from a silicon boule, and said substrate and member have concentric central openings therethrough to enable the composite disk to be mounted on a spindle or the like. .Iaddend. .Iadd.13. A composite magnetic recording disk according to claim 8, wherein said reinforcing support member is in backup relation to the recording material and includes a portion which extends outwardly beyond the substrate. .Iaddend.