ESD phenomena in GMR heads in the manufacturing process of HDD and GMR heads

It is well known that GMR heads used for hard disk drives (HDD) are very sensitive to ESD. In this report, we describe a method of categorizing ESD damage modes from a standpoint of magnetic influences to heads as observed by QST characteristics and electromagnetic characteristics like off-track profiles. In addition, we report an example of GMR stack inter-layer diffusion which is one type of hard ESD damage. We also describe an example of ESD damage that happened in the actual production process and its preventive measures as guidelines.