Hard disk drive suspension with reduced PSA change due to humidity and temperature variations

摘要

In a disk drive suspension circuit, in order to improve stability of the stable pitch static attitude (PSA) over changes in humidity, the suspended portion of the flexible circuit and/or the gimbal support arm are modified to change their response(s) to humidity. In one embodiment, hygroscopic material such as the material of the insulating layer are added to the stainless steel gimbal support arm, so that in response to humidity it bends in the opposite direction as the suspended portion of the circuit. In another embodiment, additional hygroscopic material is added to the circuit, and/or the polyimide insulating layer or the coverlayer are selectively removed, so that the net bend in the suspended portion of the circuit over humidity is reduced, ideally to a condition of zero or close to zero net bending.