Within-row wedge angle control for magnetic recording read-write heads
View Patent ↗A process for lapping a row of head sliders involves fixing the row to a lapping tool fixture, actuating each of multiple force pins to set each head slider for lapping to a respective target wedge angle, and simultaneously lapping accordingly. Each target wedge angle may be achieved by applying a respective torque to a compliant elastomer between each force pin and corresponding head slider, to transfer a pressure gradient corresponding to the torque to the corresponding head slider. Such torques may be applied through at least two wedge angle flexures interconnecting a rotatable box structure and a fixed back wall of a lapping tool, wherein the flexures virtually intersect at and define an axis of rotation about which the torques are applied. The process may further involve actuating each force pin to set each head slider for lapping to a respective reader target stripe height, and simultaneously lapping accordingly.
1. A method for lapping a row-bar of magnetic read-write head sliders wherein each head slider comprises a reader element and a writer element, wherein said row-bar has an x-axis along the direction of the row and a y-axis along the direction of a reader-writer offset associated with said head sliders in said row-bar, the method comprising:
fixing said row-bar to a lapping tool fixture;
actuating each of a plurality of force pins of said lapping tool to set each said head slider of said row-bar for lapping to a respective target wedge angle, wherein each said wedge angle corresponds to an angle relative to the y-axis; and
simultaneously lapping each said head slider according to each said respective target wedge angle.
2. The method of claim 1 , further comprising:
actuating each of said plurality of force pins to set each said head slider of said row-bar for lapping to a respective reader element target stripe height; and
simultaneously lapping each said head slider according to each said respective target stripe height.
3. The method of claim 2 , wherein said actuating for lapping to said stripe heights is performed after lapping each said head slider according to each said respective target wedge angle.
4. The method of claim 1 , wherein said actuating for lapping to said wedge angles includes applying a respective torque to a compliant elastomer between each said force pin and a corresponding said head slider, to transfer a y-direction pressure gradient corresponding to said respective torque to said corresponding head slider.
5. The method of claim 4 , wherein said actuating for lapping to said wedge angles includes changing, during said lapping to said wedge angles, at least one said torque, to dynamically change said y-direction pressure gradient corresponding to said at least one torque.
6. The method of claim 4 , wherein applying said torques includes applying through at least two wedge angle (WA) flexures interconnecting a back wall of a box structure and a fixed back wall of said lapping tool, wherein said WA flexures virtually intersect at and define an x-axis of rotation about which said torques are applied.
7. The method of claim 6 , further comprising:
wherein said x-axis of rotation is located, in a z-direction, substantially at a bottom face of said row-bar, at which said row-bar is lapped.
8. The method of claim 6 , further comprising:
wherein said x-axis of rotation is located, in a y-direction, substantially at a centroid of said row-bar.
9. A lapping tool comprising:
a box structure, said box structure including a front side housing a plurality of force pins that translate in a z-direction and a back wall;
a fixture for holding a row-bar of magnetic read-write head sliders such that each of said plurality of force pins is positioned to apply a force to a corresponding head slider of said row-bar;
a second back wall a distance from said back wall of said box structure; and
at least two flexible wedge angle (WA) flexures interconnecting said back wall of said box structure and said second back wall, such that said WA flexures virtually intersect at and define an axis of rotation about an x-axis associated with said row-bar;
wherein each said force pin, in response to actuation and based on said virtual intersection of said WA flexures, applies a torque to said corresponding head slider about said axis of rotation.
10. The lapping tool of claim 9 , further comprising:
a compliant elastomer between each said force pin and said corresponding head slider to transfer a y-direction pressure gradient corresponding to said torque from said force pin to said head slider.
11. The lapping tool of claim 10 , wherein said elastomer has a material Shore A hardness in a range of 10-90 durometer.
12. The lapping tool of claim 9 , further comprising:
at least two flexible stripe height (SH) flexures interconnecting said front side and said back wall of said box structure;
wherein each said force pin, in response to actuation, applies a z-directional force to said corresponding head slider for lapping to a respective reader element target stripe height.
13. The lapping tool of claim 9 , wherein each of said plurality of force pins is positioned to apply one or more forces targeting a single corresponding head slider of said row-bar.
14. The lapping tool of claim 9 , wherein said plurality of force pins, in response to actuation, collectively twists said row-bar to concurrently set each said head slider of said row-bar for lapping to a target wedge angle.