System, method, and apparatus for use of micro coils within a single slider test nest
View Patent ↗A precisely machined test nest holds a single hard disk drive slider. The test nest is fabricated to contain a micro pickup coil that is positioned to be able to detect magnetic flux from a write element of the slider. The micro pickup coil has highly repeatable and controllable positioning with respect to the write element. This technique also allows local magnetic field to be applied to the read element, and its small size allows excitation at higher frequencies than are currently achievable today. The coil is lithographically defined and integrated into the test nest and used on single slider testers. The low inductance of the coil allows it to be driven at high frequencies. Its position within the test nest ensures good heat sinking and enables large current pulses to be employed.
1. A test device for testing a workpiece, comprising:
a body that defines x, y, and z directions;
a nest having a rectangular, block-like shape formed in the body and having a platform extending in an x-y plane to define a z-direction stop, the nest having a reference corner that defines both x-direction and y-direction stops for precisely aligning the workpiece with respect to the nest in all of the x, y, and z-directions; and
a test element formed in the body adjacent the nest, the test element being precisely located adjacent the reference corner for testing the workpiece when the workpiece is mounted in the nest and precisely aligned with respect to the reference corner at the x, y, and z-direction stops, and the test element is adapted to couple with and test the workpiece with a high frequency magnetic test field to detect stray flux from the workpiece.
2. The test device of claim 1 , wherein the reference corner is adapted to align the workpiece within +/−5 μm of a desired alignment with respect to the test element in all of the x, y, and z-directions.
3. The test device of claim 1 , further comprising an evacuated hole formed in the body and extending to the nest for securing the workpiece in the nest during testing.
4. The test device of claim 1 , wherein the test element is selected from the group consisting of one or more coils, an array of coils, an array of loops, and an array of wires.
5. The test device of claim 1 , further comprising a wear layer formed in the nest adjacent the test element for protecting the test element from wear, and wherein the wear layer is formed from Al 2 O 3 and has a thickness of no more than 1 μm.
6. The test device of claim 1 , further comprising a heat sink substrate formed in the body adjacent the test element but opposite the nest for cooling the body, test element, and workpiece in operation, and wherein the body is ceramic, the test element is copper, and the heat sink substrate is silicon.
7. The test device of claim 1 , wherein the test element has 1 μm traces at a spacing of 1.5 μm for conducting approximately 50 mA to produce a magnetic field of approximately 200 Oe.
8. The test device of claim 1 , further comprising a wear layer formed in the nest adjacent the test element for protecting the test element from wear, and wherein the wear layer is formed from Al 2 O 3 and has a thickness of no more than 1 μm.
9. A system for testing a workpiece, comprising:
a workpiece that defines x, y, and z-directions;
a test device having a body, and a nest formed in the body having a reference corner that precisely aligns the workpiece with respect to the nest in all of the x, y, and z-directions;
a test element formed in the body beneath the nest, the test element being precisely located adjacent the reference corner for testing the workpiece when the workpiece is mounted in the nest and precisely aligned with respect to the reference corner;
a wear layer formed in the nest between the workpiece and the test element for protecting the test element from wear; and
the test element couples with and tests the workpiece with a high frequency magnetic test field to detect stray magnetic flux from a magnetic write element of the workpiece.
10. The system of claim 9 , wherein the reference corner is adapted to align the workpiece within +/−5 μm of a desired alignment with respect to the test element in all of the x, y, and z-directions.
11. The system of claim 9 , further comprising an evacuated hole formed in the body and extending to the nest for securing the workpiece in the nest during testing.
12. The system of claim 9 , wherein the test element is selected from the group consisting of one or more coils, an array of coils, an array of loops, and an array of wires.
13. The system of claim 9 , wherein the wear layer is formed from Al 2 O 3 and has a thickness of no more than 1 μm.
14. The system of claim 9 , further comprising a heat sink substrate formed in the body adjacent the test element but opposite the nest for cooling the body, test element, and workpiece in operation, and wherein the body is ceramic, the test element is copper, and the heat sink substrate is silicon.
15. The system of claim 9 , wherein the test element has 1 μm traces at a spacing of 1.5 μm for conducting approximately 50 mA to produce a magnetic field of approximately 200 Oe.
16. The system of claim 9 , wherein the nest has a rectangular, block-like shape and the workpiece has a congruent shape.
17. The system of claim 9 , wherein the workpiece is a hard disk drive slider, and the device assesses the write efficiency of a write element of the slider without flying the slider on a disk.
18. A test device for testing a workpiece, comprising:
a body that defines x, y, and z directions;
a nest formed in the body, the nest having a reference corner for precisely aligning the workpiece with respect to the nest in all of the x, y, and z-directions;
a test element formed in the body adjacent the nest, the test element being precisely located adjacent the reference corner for testing the workpiece when the workpiece is mounted in the nest and precisely aligned with respect to the reference corner;
a wear layer formed in the nest on top of the test element for protecting the test element from wear;
a heat sink substrate formed in the body adjacent the test element but opposite the wear layer for cooling the body and test element in operation, and wherein the body is ceramic, the test element is copper, and the heat sink substrate is silicon; and
an evacuated hole formed in the body and extending to the nest for securing the workpiece in the nest during testing.
19. The test device of claim 18 , wherein the test element is selected from the group consisting of one or more coils, an array of coils, an array of loops, and an array of wires.
20. A test device for testing a workpiece, comprising:
a body that defines x, y, and z directions;
a nest having a rectangular, block-like shape formed in the body and having a platform extending in an x-y plane to define a z-direction stop, the nest having a reference corner that defines both x-direction and y-direction stops for precisely aligning the workpiece with respect to the nest in all of the x, y, and z-directions;
a test element formed in the body adjacent the nest, the test element being precisely located adjacent the reference corner for testing the workpiece when the workpiece is mounted in the nest and precisely aligned with respect to the reference corner at the x, y, and z-direction stops; and
a heat sink substrate formed in the body adjacent the test element but opposite the nest for cooling the body, test element, and workpiece in operation, and wherein the body is ceramic, the test element is copper, and the heat sink substrate is silicon.
21. The test device of claim 20 , wherein the reference corner is adapted to align the workpiece within +/−5 μm of a desired alignment with respect to the test element in all of the x, y, and z-directions.
22. The test device of claim 20 , further comprising an evacuated hole formed in the body and extending to the nest for securing the workpiece in the nest during testing.
23. The test device of claim 20 , wherein the test element is selected from the group consisting of one or more coils, an array of coils, an array of loops, and an array of wires.
24. The test device of claim 20 , further comprising a wear layer formed in the nest adjacent the test element for protecting the test element from wear, and wherein the wear layer is formed from Al 2 O 3 and has a thickness of no more than 1 μm.
25. The test device of claim 20 , wherein the test element has 1 μm traces at a spacing of 1.5 μm for conducting approximately 50 mA to produce a magnetic field of approximately 200 Oe.