Manufacturing Of A Hard Disk Drive
Cute Girl • onIt & Systems 9 years ago • 10 min read

Manufacturing of a Hard Disk Drive (HDD)

A Hard Disk is the most important & vital component of a computer. In many years, it has seen significant improvements in the amount of data can store, also how fast it can retrieve. But in all these years, the basic mechanical

Structure of hard disk has remained the same. Under the case of each hard disk, you’ll see a PCB board. This houses the electronics that makes the drive do what it is expected to do. Inside the casing, the bulk of the space is occupied by one or more platters mounted one on top of the other, on a spindle on a motor. The data is stored on magnetic material on these platters. Finally, there’s the reading/ recording head, and its drive mechanism. Each face of each platter will have its own independent head. The processes may different with different disk manufacturers.


e detailed here is the process followed by Seagate, as seen at their Recording Media Operations at Ang Mo Kio, Singapore. At Seagate, hard disk manufacturing is spread across different factories, which are situated in different countries. The platters are made in one plant, and they’re prepared to hold data in another. The reading head is produced in another, while the final drive is assembled in yet another.

Here, we’ll look at how the individual platters are prepared for holding the data. The disk platter is a finely balanced piece of work, finished to microscopic tolerances. Take the smoothness of its surface, for example. The drive head rides a cushion of air microscopic distances above the surface of the platter. So, the surface can’t be too smooth, or the drive head will end up sticking to the platter. It can’t be too rough either, or the head will end up getting caught in the microscopic bumps on the surface.

Almost all the work takes place in clean rooms, where the amount of dust in the atmosphere is kept very low, and is strictly controlled and monitored. Remember the Pentium bunnies in the old Intel ads? Well, in some of the clean rooms, the workers are similarly dressed, to avoid contamination of the material they’re working with.

The platters come to the factory, packed in shipping cassettes. When they get taken in for production, they’re transferred to what are called process cassettes, which are nothing but carrying cases, as shown here. They move from one process to another in these cassettes. When the cassettes have to move from one room to another, they do so on automatic guided vehicles. This is to prevent contamination due to human contact.

The first step in getting the platter ready to record data is Mechanical Texturing. Here, roughness and groove are applied to the polished surface of the disk. This helps in depositing magnetic material on the disk later.

During the texturing process, small amounts of nickel get removed from surface of the disk and remain there. To remove this, the platter is now washed. This process is called Oliver Wash. If you look at a platter removed from a finished hard disk, you’ll see a 2-4 mm band near the center, much like the one you see on the silver side of a CD-ROM. This is the Laser Texture, the landing area where the read head comes to rest. Laser Texturing is done now. The landing area is created by creating microscopic bumps, using a laser. This prevents the head clinging to the disk surface when the disk is spinning. Time for a final cleaning of the platter. This is done using a series of ultrasonic, mega sonic and Quick Dump Rinse (QDR) steps. At the end of the final clean, the platter has an ultra-clean surface and is ready for depositing of magnetic media— a process known as sputtering. The platters now move to a Class10 clean room, in an automatic guided vehicle, described earlier. Sputtering is perhaps the most critical in the whole process of creating a recording media.

Automatic guided vehicle (center) transporting platters:

Magnetic film is coated on to substrates that are then transferred on to the platter.

There are two types of sputtering— pass-by sputtering and static sputtering.

In pass-by sputtering, disks are passed inside a vacuum chamber, where they’re

Bombarded with the magnetic material. Static sputtering uses smaller machines and each disk is picked up and sputtered individually. The sputtering material is prepared in what are called bombs, which are loaded onto the sputtering machine. The bombs are vacuum chambers with targets on either side. The platter is lifted into the bomb and is bombarded with the magnetic material. Though the process uses bombarding, my guess is that the name bomb comes from the shape of the chamber, rather than the process.

A basic factory view:

Sputtering leads to some spikes being deposited on the platter, which need to be removed? To ensure that this doesn’t lead to the scratching of the platter, lube is applied to the platter surface now. Once lube has been applied, the platters move to the buffing stage, which is basically polishing the disk while it spins around. After buffing, the platter is wiped and clean lube is evenly applied on the surface. The disk is now ready, and needs to be tested for quality. This is a three-stage process. First, a burnishing head passes over the surface, removing any bumps (asperities as the technical term goes). The glide head now goes over the disk, checking for remaining bumps if any. And finally there is the Cert head (the certifying head) that checks the surface for manufacturing defects and also measures the magnetic recording ability of the platter. Platters that pass the quality test go into final packing. They’re vacuum packed onto caddies. These are sent to the disk drive operations plant, where they’re assembled into hard disks.

The test heads in operation:

A hard disk platter over the year, you will notice that the size has not changed too much. Increased disk capacity has been achieved by improving the areal density (The amount of data that can be stored per square inch).

What is "low level formatting" an ATA (IDE) drive?

Here we describe you a low level formatting of HDD. Actually the term "low level" is a bit of a misnomer. The low level process first used years ago in MFM hard drives bears little resemblance to what we now call a "low level format" for today's ATA (IDE) drives. The only safe method of initializing all the data on a Seagate device is the Zero Fill option in Disc Wizard Starter Edition.

Why would need to Zero Fill a hard disk drive? The most common reasons to Zero Fill an ATA (IDE) hard drive are:

ü The drive has contracted a virus that cannot be removed without destroying the boot sector.

ü You are changing from one operating system to another and wish to remove everything from the drive.

How does a low Zero Fill on a hard disk drive?

ü Zero Filling an ATA (IDE) drive destroys 100% of the data on the drive. Make sure the drive is completely backed up before proceeding.

ü The Zero Fill option in Disc Wizard Starter Edition is the only safe method for use with Seagate hard drives. Some system BIOSs may include a Low Level Format option; use these at your own risk, as this may produce undesirable results.

Disc Wizard Starter Edition can be downloaded as a part of the Disc Wizard package. It includes two Zero Fill options, partitioning options, and high-level formatting options. Zero Fill writes zeros in each data sector up to the complete capacity of the drive and will clean up some file system defects.

The download routine for Disc Wizard Starter Edition creates a bootable diskette. Boot from the diskette to start Disc Wizard Starter Edition. After startup, select Utilities than Zero Fill Drive (Quick) or Zero Fill Drive (Full). Select the drive you want to erase, then select Zero Fill or Low Level.

Zero Fill Drive (Quick) will write over the beginning of the drive which includes the critical partition information, eliminating all partitions and information on the drive including the Master boot record. This is useful if you have a drive that has a corrupted partition or that you wish to erase to reinstall a fresh operating system and new data.

Zero Fill Drive (Full) will write over the entire data area of the drive. This is useful if a drive has bad sectors that cannot be fixed by the operating system. This will also erase all the data on the drive, but it will take several hours.

When the process completes, reboot the system from the operating system install CD and follow the instructions to prepare (partition and format) the drive and install the operating system.

Hard Disk Drive Troubleshooter -Error Messages

NTLDR Errors

There are four types of primary reasons why we might get an NTLDR error:

ü The boot order is not set to boot from CD-Rom first. To install Windows XP you need to boot from the CD-Rom. More computers default set to boot from the hard drive first, but will boot from the CD if there is no partition on the hard disk drive. Once we use DWSE to create partition the computer attempts to boot from this new partition and detects that the partition has no operating system installed and reports missing NTLDR. To fix this type of the issue you will need to adjust the boot order of your computer in the BIOS (computer setup).

ü If left a floppy in the diskette drive. Check and confirm if don't have any floppy diskettes in the drive.

ü If computer have more than 1 CD/ATAPI device installed on the secondary channel, be sure that you are booting from the "master" CD/ATAPI device. You can verify that which drive is the master versus slave CD/ATAPI device by booting into your CMOS/BIOS setup in case those devices are currently set for "Cable-Select" or you just don't know which one is the master device. If this has been checked then try removing the "slave" CD/ATAPI device from the channel to see if the issue resolves itself.

ü The CD of Window XP prompted to 'press any key' and you missed it. When booting from the Windows XP CD it will look for partitions if your drive is blank it will boot directly from the CD. If the drive has a partition it should prompt you to 'press any key’ to continue so that you don't have to remove the CD after the reboot that occurs during installation. You have to press any key very quickly because this message will time out in a very short period of a few seconds then you will see an NTLDR error on the screen.

ü Windows has not been installed. If the operating system has not been installed on computer then the system will report an NTLDR message until you boot from the install media and install the operating system to the hard drive.

The other Solution:

If above cant solve the problem & Windows unable to start in any case. Than try with following solutions:

o solve the NTDLR missing problem, boot the PC form Windows XP/2000 CD & when a blue screen show some option to go forward then select option with pressing ‘R’ to recovery console. This is a command prompt type screen which wants to user name & password to access the system folders. Type the administrator user name & password. Then type in "copy x:\i386\NTDLR c:\ press enter“ &

copy x:\i386\ c:\ press enter“

This will solve the problem, if persist than need to reinstall windows with repair option

For more detail on NTLDR missing errors plz visit Microsoft's support site.


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  • Guest 7 years ago
    It is very useful. Thank you very much for your detail explanation