Method of making sintered body and method for manufacturing magnetic head wafer

A wafer for magnetic heads, the wafer comprising:

• a sintered body;
• and
• an insulating film provided on the sintered body;
• wherein the sintered body includes a sintered mixture of a first type of powder particles and a second type of powder particles, the first type of powder particles being made of a first material, the second type of powder particles being made of a second material that has a different etch susceptibility from the first material, and
• wherein a first concave region is defined to a depth of at least about 10 nm under the surface of the sintered body and a second concave region is defined under the first concave region, respectively, and identification information is provided on the surface of the sintered body, the first concave region being defined by an etched portion of both the first and second types of powder particles, the second concave region being defined by an etched portion of only the first type of powder particles.

A magnetic head comprising:

• a substrate;
• and
• an electrical/magnetic transducer provided on the substrate;
• wherein the substrate is made of a mixture of a first type of powder particles and a second type of powder particles, the first type of powder particles being made of a first material, the second type of powder particles being made of a second material that has a different etch susceptibility from the first material;
• and
• wherein a first concave region is defined to a depth of at least about 10 nm under the surface of the substrate and a second concave region is defined under the first concave region, respectively, and identification information is provided on the surface of the substrate, the first concave region being defined by an etched portion of both the first and second types of powder particles, the second concave region being defined by an etched portion of only the first type of powder particles.

A storage medium drive comprising:

• a magnetic head, which includes a substrate and an electrical/magnetic transducer provided on the substrate;
• a storage medium with a magnetic recording film from and on which information is read or written by the magnetic head;
• and
• a motor to drive the storage medium;
• wherein the substrate is made of a mixture of a first type of powder particles and a second type of powder particles, the first type of powder particles being made of a first material, the second type of powder particles being made of a second material that has a different etch susceptibility from the first material;
• and
• wherein a first concave region is defined to a depth of at least about 10 nm under the surface of the substrate and a second concave region is defined under the first concave region, respectively, and identification information is provided on the surface of the substrate, the first concave region being defined by an etched portion of both the first and second types of powder particles, the second concave region being defined by an etched portion of only the first type of powder particles.