Method for manufacturing a group of head gimbal assemblies
View Patent ↗A system and method for the production level screening of low flying magnetic heads in the manufacture of disk drive head disk assemblies (HDAs) is disclosed. A test disk is provided and has a plurality of bumps extending from at least one surface thereof. The test disk is rotated to fly a head of a head gimbal assembly selected from the group adjacent the surface of the test disk. An interaction of the head with one or more of the plurality of bumps may be sensed and the head gimbal assembly may be screened out from the group in response to the sensing of the interaction.
1. A method for manufacturing a group of head gimbal assemblies, the method comprising the following acts:
providing a test disk having a plurality of bumps extending from at least one surface thereof;
forming at least a first portion of said plurality of bumps on said test disk to at least a predetermined height;
rotating said test disk to fly a head of a head gimbal assembly selected from the group adjacent said at least one surface of said test disk;
sensing an interaction of said head with one or more of said plurality of bumps; and
screening out said head gimbal assembly selected from the group in response to said sensing of said interaction,
wherein the act of sensing is accomplished temporally adjacent a dynamic electrical test of said head gimbal assembly selected from the group and wherein the predetermined height is between about 2 nm and about 12 nm.
2. The method of claim 1 , wherein the act of sensing is accomplished at least partially concurrently with the dynamic electrical test of said head gimbal assembly selected from the group.
3. The method of claim 1 , wherein the act of providing said test disk further comprises:
focusing a laser beam on said test disk at selected locations on said at least one surface to form said plurality of bumps.
4. The method of claim 1 , wherein the head gimbal assembly selected from the group is arranged in a head stack assembly prior to the rotating of the test disk.
5. The method of claim 4 , further comprising:
suspending the head gimbal assembly selected from the group adjacent to said at least one surface of said test disk.
6. The method of claim 5 , wherein the act of sensing is accomplished substantially concurrently with the dynamic electrical test of the head gimbal assembly selected from the group.
7. The method of claim 1 , wherein the act of rotating said test disk further comprises:
placing said test disk on a spinstand and controllably rotating the spin stand proximate to the head gimbal assembly selected from the group.
8. The method of claim 1 , wherein the act of sensing an interaction of said head further comprises:
monitoring an acoustic emission of a sensor affixed to a test arm associated with the head gimbal assembly selected from the group.
9. A method for manufacturing a group of head gimbal assemblies the method comprising the following acts:
providing a test disk having a plurality of bumps extending from at least one surface thereof;
forming at least a first portion of said plurality of bumps on said test disk to at least a predetermined height;
rotating said test disk to fly a head of a head gimbal assembly selected from the group adjacent said at least one surface of said test disk;
sensing an interaction of said head with one or more of said plurality of bumps; and
screening out said head gimbal assembly selected from the group in response to said sensing of said interaction,
wherein the act of sensing is accomplished temporally adjacent a dynamic electrical test of said head gimbal assembly selected from the group and wherein the predetermined height is greater than a glide avalanche height that is characteristic of a lot of product disks to be used together with the group of head disk assemblies in later manufacture of a quantity of disk drives.
10. A method for manufacturing a group of head gimbal assemblies the method comprising the following acts:
providing a test disk having a plurality of bumps extending from at least one surface thereof;
forming at least a first portion of said plurality of bumps on said test disk to at least a predetermined height;
rotating said test disk to fly a head of a head gimbal assembly selected from the group adjacent said at least one surface of said test disk;
sensing an interaction of said head with one or more of said plurality of bumps; and
screening out said head gimbal assembly selected from the group in response to said sensing of said interaction,
wherein the act of sensing is accomplished temporally adjacent a dynamic electrical test of said head gimbal assembly selected from the group and wherein the predetermined height is less than about a 1.5 sigma lower design limit on a flying height that is characteristic of the group of head gimbal assemblies.
11. The method of claim 10 , wherein the predetermined height is less than about a 3 sigma lower design limit on a flying height that is characteristic of the group of head gimbal assemblies.