Western Digital Technologies, Inc.

Western Digital (fremont), Inc.

Cliff C Zhang

Tzong-Shii Pan

Yaw Shing Tang

Sergey G Muchiyev

Maribel Castro

Measurement circuitry is disclosed that is configured to be coupled to a load through a transmission line. A first AC signal having a frequency &#x3c9;is applied to the transmission line and a first input impedance of the transmission line is measured. A second AC signal having a frequency &#x3c9;is applied to the transmission line and a second input impedance of the transmission line is measured, wherein the frequency &#x3c9;is different than the frequency &#x3c9;. A third AC signal having a frequency &#x3c9; is applied to the transmission line and a third input impedance of the transmission line is measured, wherein the frequency &#x3c9; is different than the frequency &#x3c9;and different than the frequency &#x3c9;. A resistance of the load is measured based on the measured first input impedance, the measured second input impedance, and the measured third input impedance.

Measuring a load resistance coupled to a transmission line

A method for head stack assembly (HSA) rework is disclosed. A first head gimbal assembly (HGA) includes a first suspension attached to an arm of the HSA, and a first flexure tail that terminates in a first bonding region that is bonded to a flexible printed circuit (FPC) of the HSA. The first HGA is removed by cutting the first bonding region from a remainder of the first flexure tail and detaching the first suspension from the arm. The first bonding region of the first flexure tail is left bonded to the FPC. A replacement HGA includes a replacement suspension and a replacement flexure tail that terminates in a second bonding region. The replacement HGA is installed on the HSA by attaching the replacement suspension to the arm, overlaying the second bonding region on the first bonding region, and bonding the second bonding region to the first bonding region.

Method for head stack assembly rework

A disk drive suspension assembly has a load beam and a laminated flexure attached to the load beam. The laminated flexure includes a structural layer with a head mounting tongue, and first and second conductive layers. A first dielectric layer is disposed between the structural layer and the first conductive layer, and a second dielectric layer is disposed between the first conductive layer and the second conductive layer. The first conductive layer includes a first plurality of adjacent traces, and the second conductive layer includes a second plurality of adjacent traces that are staggered relative to the first plurality of adjacent traces. The adjacent traces of each plurality are electrically common and joined at a distal junction adjacent the head mounting tongue and joined at a proximal junction at the flexure tail terminal region.

Disk drive suspension assembly with flexure having dual conductive layers with staggered traces

A head stack assembly (HSA) for a disk drive includes an actuator body, at least one actuator arm extending from the actuator body, and a flexible printed circuit (FPC). The FPC may include a FPC conductive layer having a plurality of FPC traces that terminate at respective ones of a plurality of electrically conductive FPC bond pads. The FPC may include a metallic FPC stiffener layer having a surface that underlies and faces the FPC bond pads. The FPC stiffener layer surface may include a plurality of recessions having a depth of at least 25 microns. A FPC dielectric layer may be disposed between the FPC conductive layer and the metallic FPC stiffener layer. One or more of the plurality of FPC bond pads may be internally patterned to define a FPC bond pad mesh with a plurality of openings therethrough.

Disk drive head stack assembly having a flexible printed circuit with bond pads having reduced capacitance

A disk drive suspension assembly has a laminated flexure that includes a structural layer, first and second conductive layers, a first dielectric layer disposed between the structural layer and the first conductive layer, and a second dielectric layer disposed between the first conductive layer and the second conductive layer. The first conductive layer includes at least a first conductive trace and a second conductive trace, and the second conductive layer includes at least a third conductive trace and a fourth conductive trace. The first conductive trace is electrically connected to the fourth conductive trace by a first conductive via through the second dielectric layer, and the second conductive trace is electrically connected to the third conductive trace through a second conductive via through the second dielectric layer. The third conductive trace overlies the first conductive trace, and the fourth conductive trace overlies the second conductive trace.

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San Jose, CA, United States of America

Cliff C Zhang