page_title: Hard disk drive platter
section_title: Manufacture
hierarchical_section_title: Hard disk drive platter / Manufacture
caption_attribution_description: English: Toshiba MK1403MAV - broken glass platter
context_page_description: A hard disk drive platter is the circular disk on which magnetic data is stored in a hard disk drive. The rigid nature of the platters in a hard drive is what gives them their name. Hard drives typically have several platters which are mounted on the same spindle. A platter can store information on both sides, requiring two heads per platter.
context_section_description: Platters are typically made using an aluminium, glass or ceramic substrate. As of 2015, laptop hard drive platters are made from glass while aluminum platters are often found in desktop computers.  In disk manufacturing, a thin coating is deposited on both sides of the substrate, mostly by a vacuum deposition process called magnetron sputtering. The coating has a complex layered structure consisting of various metallic (mostly non-magnetic) alloys as underlayers, optimized for the control of the crystallographic orientation and the grain size of the actual magnetic media layer on top of them, i.e. the film storing the bits of information. On top of it a protective carbon-based overcoat is deposited in the same sputtering process. In post-processing a nanometer thin polymeric lubricant layer gets deposited on top of the sputtered structure by dipping the disk into a solvent solution, after which the disk is buffed by various processes to eliminate small defects and verified by a special sensor on a flying head for absence of any remaining asperities or other defects (where the size of the bit given above roughly sets the scale for what constitutes a significant defect size). In the hard-disk drive the hard-drive heads fly and move radially over the surface of the spinning platters to read or write the data. Extreme smoothness, durability, and perfection of finish are required properties of a hard-disk platter.
  In 1990, Toshiba released the MK1122FC, the first hard drive to use a glass substrate, replacing the aluminium alloys used in earlier hard drives. It was originally designed for laptops, for which the greater shock resistance of glass substrates are more suitable. Around 2000, other hard drive manufacturers started transitioning from aluminum to glass platters because glass platters have several advantages over aluminum platters.
  In 2005–06, a major shift in technology of hard-disk drives and of magnetic disks/media began. Originally, in-plane magnetized materials were used to store the bits but has now been replaced by perpendicular recording.
  The reason for this transition is the need to continue the trend of increasing storage densities, with perpendicularly oriented media offering a more stable solution for a decreasing bit size. Orienting the magnetization perpendicular to the disk surface has major implications for the disk's deposited structure and the choice of magnetic materials, as well as for some of the other components of the hard-disk drive (such as the head and the electronic channel).
caption: Destroyed hard disk, glass platter visible
exif: {"Image ImageDescription": "Toshiba MK1403MAV - broken glass platter", "Image Make": "Canon", "Image Model": "Canon EOS 5D Mark IV", "Image XResolution": "240", "Image YResolution": "240", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Adobe Photoshop Lightroom 6.14 (Windows)", "Image DateTime": "2019:01:12 21:43:11", "Image Artist": "Raimond Spekking", "Image ExifOffset": "300", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "996", "Thumbnail JPEGInterchangeFormatLength": "13068", "EXIF ExposureTime": "1/2", "EXIF FNumber": "14", "EXIF ExposureProgram": "Aperture Priority", "EXIF ISOSpeedRatings": "200", "EXIF SensitivityType": "Recommended Exposure Index", "EXIF RecommendedExposureIndex": "200", "EXIF ExifVersion": "0230", "EXIF DateTimeOriginal": "2019:01:10 20:32:56", "EXIF DateTimeDigitized": "2019:01:10 20:32:56", "EXIF ShutterSpeedValue": "1", "EXIF ApertureValue": "761471/100000", "EXIF ExposureBiasValue": "0", "EXIF MaxApertureValue": "3", "EXIF MeteringMode": "Pattern", "EXIF Flash": "Flash did not fire, compulsory flash mode", "EXIF FocalLength": "100", "EXIF SubSecTimeOriginal": "42", "EXIF SubSecTimeDigitized": "42", "EXIF ColorSpace": "sRGB", "Interoperability InteroperabilityIndex": "R98", "Interoperability InteroperabilityVersion": "[48, 49, 48, 48]", "EXIF InteroperabilityOffset": "872", "EXIF FocalPlaneXResolution": "61166933/32768", "EXIF FocalPlaneYResolution": "61166933/32768", "EXIF FocalPlaneResolutionUnit": "3", "EXIF CustomRendered": "Normal", "EXIF ExposureMode": "Auto Exposure", "EXIF WhiteBalance": "Auto", "EXIF SceneCaptureType": "Standard", "EXIF BodySerialNumber": "183056000531", "EXIF LensSpecification": "[100, 100, 0/0, 0/0]", "EXIF LensModel": "EF100mm f/2.8 Macro USM", "EXIF LensSerialNumber": "0000000000"}