1979: Thin-film heads introduced for large disks
Photolithography enables a new generation of high-density disk drives




First introduced in 1979 for large disk files on the IBM 3370 Direct Access Storage Unit, thin-film technology enabled new read/write head structures that increased HDD recording densities. Derived from work at IBM’s Thomas J. Watson Research Center, thin-film processes employed photolithographic techniques similar to those used on semiconductor devices to fabricate disk drive heads with smaller size and greater precision than ferrite-based designs. Successive photomasking, etching, and deposition steps (both in vacuum and by wet plating) built up thin layers of magnetic (Ni-Fe), insulating, and copper coil wiring materials on ceramic substrates that were then physically separated into individual read/write head circuits integrated with their air bearing significantly reducing the manufacturing cost per unit.
The small physical size of the 3370 slider allowed the flying height above the disk to be reduced by nearly 30% from the Winchester design, from 18 down to 13 microinches (320 nm), and raised the areal density by a factor of 2x to 7.7 Mb per square inch. With seven 14-inch diameter disks, Model 1 versions of the 3370 had a capacity of 571 MB. Using similar technology the 3380 shipped in 1981 offered a four-fold increase in capacity. Together with other advances, increasing the 8 turns of coil wiring employed on the 3370 and 3380 heads to 31 turns, in 1987 the 3380K drive achieved an areal density of 35.9 Mb/sq. in. Produced for over 15 years, the 3380 family was one of most successful products in the history of IBM. Experience with volume production of thin film materials established the foundation for processes, tools, testers, etc. that enabled magnetorestive (MR) heads to deliver significant HDD areal density increases.
Contemporary Documents
- “Systems IBM 3370 Direct Access Storage Description” (Retrieved on 2.12.15 from: http://bitsavers.trailing-edge.com/pdf/ibm/dasd/3370/GA26-1657-1_3370_Direct_Access_Storage_Description_Sep79.pdf)
- “IBM 3380 Direct Access Storage: Reference Summary” (Retrieved on 2.14.15 from: ed-thelen.org/comp-hist/IBM-ProdAnn/3380das.pdf)
- Dill, Frederick H., et. al. "Characterization of Positive Photoresist" IEEE Transactions on Electronic Devices (July 1975) pp. 445 - 452
- Dill, Frederick Hayes, “Combination inductive write head and magnetoresistive (MR) read head with improved topography” U.S. Patent 6,324,036 (Filed: May 26, 1999 Issued: Nov 27, 2001)
- Romankiw, Lubomyr T., David A. Thompson. “Thin film inductive transducer,” U.S. Patent 4,295,173 (Filed: October 18, 1979 Issued: October 13, 1981)
More Information
- Cord, B., et. al. “Application of magnetic thin films for high-density data storage” Thin Solid Films (Vol: 175 August 1989) pp: 287–293
- Chiu, A. et al. "Thin Film Inductive Heads" IBM J. Res. Develop.(vol 40, No.3, May 1996) pp. 283
- Kryder, Mark H. “Magnetic thin films for data storage” International Workshop on Science and Technology of Thin Films for the 21st Century (Vol: 216, No: 1, 28 August 1992) pp: 174–180
- “IBM 3370 direct access storage device” (Retrieved on 2.12.15 from: http://www-03.ibm.com/ibm/history/exhibits/storage/storage_3370.htm)
- “IBM 3380 direct access storage device” (Retrieved on 2.12.15 from: http://www-03.ibm.com/ibm/history/exhibits/storage/storage_3380.html)
- “IBM 3380” (Retrieved on 2.15.15 from: http://chmhdd.wikifoundry.com/page/IBM+3380)
- "Thin film" recording head copper coil” (Retrieved on 2.12.15 from: http://www-03.ibm.com/ibm/history/exhibits/storage/storage_PH12-60.html)
- Stevens, Louis D. “Data Storage on Hard Magnetic Disks” in Eric D Daniel, C. Denis Mee, Mark H. Clark eds. Magnetic Recording: The First 100 Years, IEEE Press (1999) p. 290
- IBM Magnetic head development (specifications, etc) (Retrieved on 2.12.15 from: https://www-03.ibm.com/ibm/history/exhibits/storage/storage_magnetic.html)
- “Milestones: IBM Thomas J. Watson Research Center, 1960 – 1984” Engineering and Technology History Wiki (for thin film heads) (Retrieved on 12.2.15 from: http://ethw.org/Milestones:IBM_Thomas_J._Watson_Research_Center,_1960_-_1984)
Oral Histories
- “International Business Machines Corporation (IBM) 3380 disk drive oral history panel”Computer History Museum Oral History # 102657932 (2006-01-03)
- “Advanced ferrite disk heads oral history panel” Computer History Museum Oral History # 102657927 (2005-11-03)
- “Advanced thin film disk heads oral history panel” Computer History Museum Oral History # 102657929 (2005-11-11)
- "Dill, Frederick (Rick) H. oral history" Computer History Museum Oral History # TBA Ref x7520.2015 (2015-06-11)
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