Method of predicting plate lapping properties to improve slider fabrication yield

• US 6,939,200 B2
• Filed: 09/16/2003
• Issued: 09/06/2005
• Est. Priority Date: 09/16/2003
• Status: Expired due to Fees

• Current Assignee: Hitachi Global Storage Technologies Netherlands BV (Western Digital Corporation)
• Original Assignee: Hitachi Global Storage Technologies Netherlands BV (Western Digital Corporation)
• Inventors: Beaucage, Jacey Robert, Tzeng, Huey-Ming, Goddu, Paul Arthur
• Primary Examiner(s): Hail, III, Joseph J.
• Assistant Examiner(s): McDonald, Shantese L.
• Application Number:
  US10/663,606
• Publication Number:
  US 20050059322A1
• Time in Patent Office: 721 Days
• Field of Search: 451/5, 451/8, 451/9, 451/10, 451/11, 451/41, 451/285, 451/286, 451/287, 451/288, 451/364
• US Class Current: 451/5
• CPC Class Codes: B24B 49/00 Measuring or gauging equipment for controlling the feed movement of the grinding tool or work; Arrangements of indicating or measuring equipment, e.g. for indicating the start of the grinding operation B24B33/06, B24B37/005 take precedence; if applicable to other machine tools, B23Q15/00 - B23Q17/00 take precedence
• CPC Class Codes: B24B 51/00 Arrangements for automatic control of a series of individual steps in grinding a workpiece if applicable to other machine tools, G05B takes precedence

Abstract

A method of predicting the lapping property of a charged lapping plate uses samples with a known lap surface. The samples are lapped on the plate and a non-invasive sensor is used to determine the lapping rate under a fixed load and rotation speed. The total frictional force of the samples is measured during the lapping to calculate the friction and Preston coefficients of the plate. The samples are held in place while the plate rotates and the sensor measures the distance to the plate. The plate rotates for a specific time so that adequate removal of the pad material has occurred. The lapping rate is determined from a change in the gap distance over a time interval. The lapping rate and friction are then assessed to determine if the plate is lapping worthy.

Claims

1. A method of predicting the lapping property of a lapping plate, comprising:

(a) positioning a tool on a lapping plate;

(b) rotating the lapping plate;

(c) restraining the tool relative to the lapping plate;

(d) measuring frictional force between the tool and the lapping plate;

(e) measuring a consumption of the tool by the lapping plate by detecting a gap distance between the tool and the lapping plate; and

(f) determining a lapping rate of the lapping plate.

2. The method of claim 1, further comprising rotating the lapping plate for a specific time so that adequate removal of material from the tool occurs, determining the lapping rate over a time interval, and assessing the lapping rate and friction to determine if the lapping plate is acceptable.

3. The method of claim 1, further comprising determining the lapping rate under a fixed load and a fixed rotation speed, and thereby calculating a coefficient of friction and a Preston coefficient of the lapping plate.

4. The method of claim 1, wherein step (e) is non-invasive.

5. The method of claim 1, further comprising charging the lapping plate with abrasive.

6. The method of claim 1, wherein step (d) comprises using a strain gage.

7. A method of predicting the lapping property of a lapping plate, comprising:

(a) positioning a tool on a lapping plate;

(b) rotating the lapping plate;

(c) restraining the tool relative to the lapping plate by holding the tool with a set of guide wheels that keep the tool in place when the lapping plate is rotating;

(d) measuring frictional force between the tool and the lapping plate;

(e) measuring a consumption of the tool by the lapping plate; and

(f) determining a lapping rate of the lapping plate.

8. A method of predicting the lapping property of a lapping plate, comprising:

(a) positioning a tool on a lapping plate;

(b) rotating the lapping plate;

(c) restraining the tool relative to the lapping plate;

(d) measuring frictional force between the tool and the lapping plate;

(e) measuring a consumption of the tool by the lapping plate;

(f) determining a lapping rate of the lapping plate; and

further comprising

adding a weight to the tool so that the tool and the lapping plate experience a pressure that is analogous to a slider lapping pressure.

9. A method of predicting the lapping property of a lapping plate, comprising:

(a) positioning a tool on a lapping plate that is charged with abrasive;

(b) rotating the lapping plate for a specific time to remove material from the tool;

(c) restraining the tool relative to the lapping plate;

(d) measuring frictional force between the tool and the lapping plate;

(e) measuring a consumption of the tool by the lapping plate non-invasively and detecting a gap distance between the tool and the lapping plate; and

(f) determining a lapping rate of the lapping plate over a time interval, and assessing the lapping rate and friction to determine if the lapping plate is acceptable, wherein the lapping rate is determined under a fixed load and a fixed rotation speed, and thereby calculating a coefficient of friction and a Preston coefficient of the lapping plate.

10. The method of claim 9, wherein step (d) comprises using a strain gage.

11. A method of predicting the lapping property of a lapping plate, comprising:

(a) positioning a tool on a lapping plate that is charged with abrasive;

(b) rotating the lapping plate for a specific time to remove material from the tool;

(c) restraining the tool relative to the lapping plate by holding the tool with a set of guide wheels that keep the tool in place when the lapping plate is rotating;

(d) measuring frictional force between the tool and the lapping plate;

(e) measuring a consumption of the tool by the lapping plate; and

(f) determining a lapping rate of the lapping plate over a time interval, and assessing the lapping rate and friction to determine if the lapping plate is acceptable, wherein the lapping rate is determined under a fixed load and a fixed rotation speed, and thereby calculating a coefficient of friction and a Preston coefficient of the lapping plate.

12. A method of predicting the lapping property of a lapping plate, comprising:

(a) positioning a tool on a lapping plate that is charged with abrasive;

(b) rotating the lapping plate for a specific time to remove material from the tool;

(c) restraining the tool relative to the lapping plate;

(d) measuring frictional force between the tool and the lapping plate;

(e) measuring a consumption of the tool by the lapping plate;

(f) determining a lapping rate of the lapping plate over a time interval, and assessing the lapping rate and friction to determine if the lapping plate is acceptable, wherein the lapping rate is determined under a fixed load and a fixed rotation speed, and thereby calculating a coefficient of friction and a Preston coefficient of the lapping plate; and

further comprising

adding a weight to the tool so that the tool and the lapping plate experience a pressure that is analogous to a slider lapping pressure.