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Q : Why is the RPM speed important?

A : As we know, the information (or data) is written on the disk's magnetic layers in concentric tracks known as cylinders. When information needs to be written or read from the disk the location for the read or write will on average not be under the head. If a disk spins faster, this location will move under the head sooner. This means that access to information on the drive is faster. The time the head requires to access the data (access time) depends on a number of factors, such as RPM, bandwidth of the servo, stability of the system, acceleration and settle capability of the actuator. The high RPM drive has faster access time, a must for high performance drives. In addition, generally the streaming data rate is higher for a higher rpm, however this is also a function of the bpi and the channel.

Q : What does an HGA / HSA customer do?

A : Magnecomp's direct customers are HGA (Head Gimbal Assembly) manufacturers. The HGA customers make or procure their own magnetic heads and bond the slider to the suspension. Next they attach the leads from the suspension to the device (head) pads to complete the electrical connection. Once the HGAs are built, the next step is building the HSA, or Head Stack Assembly. At the HSA level the HGAs are attached to E-block actuator arms via a swaging process and all the leads from the heads are connected to a pre-amp chip. The HSA is then assembled in an HDD, or Hard Disk Drive.

Q : Why is a lifter tab popular?

A : A lifter tab is generally required for dynamic load-unload types of HGAs. Dynamic load-unload is used for improved non-operation shock performance in a mobile drive by removing the head from the possibility of any contact with the disk when the drive is not in operation by moving and parking the head completely outside the OD of the disk on a load ramp. Dynamic load-unload also eliminates the contact between the head and the disk in all drives when they are powered down. This eliminates the need for the drive to be designed to include features to overcome stiction such as texture on the disk or a torque amplification algorithm in the motor drive circuit. In most of the cases the lift tabs are at the front end of the suspension. This allows the HGA lift tab to have sufficient space between the disk and the load ramp (the curved surface upon which the lift tab slides up and down when the suspension moves to and from a state of rest). The lift tab has to be very smooth such that it does not remove material from the ramp, which is generally made of a hard plastic, creating debris in the drive. Also, a lift tab located further from the mount plate has a higher moment arm and a lower friction force to lift the HGA.

Q : Why are mount plates necessary?

A : A mount plate is necessary for a number of reasons. It provides a stable datum for suspension manufacturing and also for component level testing for an HGA. Also, mount plates can easily be swaged to an actuator arm. In the swaging process the hub portion of the mount plate is enlarged by passing a number of balls through it so that there is positive interference with the arm slot. This is an inexpensive and reliable way to attach the HGAs to HSAs.

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