Method of reducing ESD damage in thin film read heads which enables measurement of gap resistance

摘要

A first read gap layer has a resistance RG1 between a first shield layer and one of the first and second lead layers of a read head and the second read gap layer has a resistance RG2 between a second shield layer and said one of the first and second lead layers of the read head. A connection is provided via a plurality of resistors between a first node and each of the first and second shield layers wherein the plurality of resistors includes at least first and second resistors RS1 and RS2 and the first node is connected to said one of the first and second lead layers. A second node is located between the first and second resistors RS1 and RS2. An operational amplifier has first and second inputs connected to the first and second nodes respectively so as to be across the first resistor RS1 and has an output connected to the first node for maintaining the first and second nodes at a common voltage potential. In a first embodiment the first and second shield layers are shorted together. A test instrument is then employed for determining the combined parallel resistance of the resistors RS1 and RS2 by having a first side of the test instrument connected to the first node and the second side connected to each of the first and second shield layers. In the second embodiment a third resistor RS3 is connected between the second node and one of the shield layers, such as the second shield layer. The test instrument can determine the resistances of the first and second gap layers separately by being connected between the first node and the first shield layer for the resistance of the first gap layer or between the first node and the second shield layer for the resistance of the second gap layer.