Hard disk drive (HDD) is a kind of data storage device that applies magnetic storage to store information by magnetic material coated rotating disk. Hard disk drive (HDD) has been became the second generation storage device after introduced by IBM in 1956. The solid state drive (SSD) start to hit the market share of hard disk drive (HDD) in recent years.
Magnets in hard disk drive
The voice coil motor (VCM) and the spindle motor are the critical components for hard disk drive. The type of magnet in the voice coil motor (VCM) and the spindle motor are sintered NdFeB magnet and compression molded NdFeB magnet respectively. The hard disk drive is still a main consumer for magnet industry at present.
The purpose of cleanliness measurement on hard disk drive magnet
For hard disk drive, the gap between head and disc only 2-3 micrometer during high-speed rotating. Basically all the dust particle’s diameter is larger than this gap. The high speed rotating will also produce static electricity. Therefore the surface of disk will be scratched by dust particles which absorbed by static electricity.
In order to avoid the pollution of dusk particle, the parts for hard disk drive need to be packaged in high-level clean room.
Beyond the dust particles, the chemical substances in hard disk drive parts are also very important. The coating for spindle motor magnet is epoxy resin, and the epoxy resin is a very simple coating for compression molded magnet. The existing state of Tin in epoxy resin electrophoretic painting can be divided into inorganic Tin and organic Tin. The internal temperature of the hard disk drive will rise after long period runs, and then the organic tin will be released due to its low melting point. The data will lose after released organic tin deposited on the surface of magnetic storage medium.
How to measure the cleanliness of hard disc drive magnet?
The test item of cleanliness include:
- FTIR analysis
- Ion Chromatography
- Liquid particle counter (LPC) analysis
