The electrical breakdown behavior and damage mechanisms for a recording head flying over a charged hard disk with and without an asperity is studied. It was found that the breakdown voltage flying over a 30 nm high asperity was as low as 1.4V, a 50% reduction compared with a smooth disk without the asperity. Also, the read sensor was easily damaged physically and magnetically when breakdown occurred while flying over the asperity. It is concluded that the inclusion of asperities in electrical breakdown testing is critically important in determining the lowest breakdown voltage and assessing the likelihood of damage to the sensor.

Co-author: Dr. Al Wallash, Advanced Technology Group, Hitachi GST