Metal working – Means to assemble or disassemble – Means to assemble electrical device
Reexamination Certificate
1998-02-06
2001-05-29
Hall, Carl E. (Department: 3729)
Metal working
Means to assemble or disassemble
Means to assemble electrical device
C029S603060, C029S760000
Reexamination Certificate
active
06237215
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to magnetic heads and in particular to improved methods and test fixtures for assembling and electrically testing a magnetic head.
DESCRIPTION OF THE PRIOR ART
Magnetic read/write heads are becoming increasingly more difficult to manufacture due to the tighter performance requirements and design tolerances set by the industry. During conventional head manufacturing, an air bearing slider is joined to a stainless steel suspension. When the head is completed, it is tested. However, once bonded, the components cannot be readily disassembled without damage.
In operation, the slider is supported by an air bearing as the magnetic medium or disk is rotated. The air bearing is at most a few microinches thick, and is determined by the geometry of the slider bearing surfaces and the “gram load”. As used herein, “gram load” means the load applied by the suspension against the slider forcing it toward the magnetic medium, as the slider flies above the magnetic medium. In proximity heads, the sensor portion of the slider may lightly contact the surface of the magnetic disk. To reduce the effects of the suspension tolerances on the slider flying attitude, the slider is secured to a gimbal mount comprised of a thin metal leaf spring pivoting over a raised dimple on the suspension. The dimple is also referred to as the “load point”.
The testing of a magnetic head is performed by mounting it over a test magnetic disk, and by writing and reading data on the disk. Some of the critical operational and testing parameters are the attitude of the slider and the transducer deposited thereon, relative to the disk, and the air bearing thickness. Ideally, the suspension is straight and the suspension load point is located directly over the center of the pressure distribution of the air bearing. Head performance is improved by minimizing the flying height of the slider and its transducer. If the air bearing is too thin or produces too high a contact force in proximity heads, the head will contact and damage the magnetic disk because of other tolerances in the disk drive, such as disk runout and spindle bearing tolerances.
After bonding and testing, the transducer wiring is routed along the suspension, and is typically threaded through an insulating tubing or “sleeving”. The transducer wiring is retained in place by means of crimp tabs that are bent against the wiring. The bending of the crimp tabs frequently distorts the suspension and adversely affects the suspension attitude and head performance. As a result, some of the existing techniques for bonding and testing of the transducer in a static state are not completely accurate.
SUMMARY OF THE INVENTION
An object of this invention is to provide an improved process for optimally positioning a slider relative to a magnetic head suspension, and for testing magnetic head performance.
It is another object of this invention to minimize the need for electrical testing after the completion of the magnetic head, by determining at the time of bonding whether the slider is properly connected, and the way in which the manufacturing tolerances affect the final flying performance of the head. This is accomplished by actually flying the head and analyzing its dynamic performance before the final assembly of the head.
It is still another object of this invention to automate and individualize the bonding process of the slider on the suspension.
According to this invention, a test fixture for assembling and electrically testing a magnetic head includes a fixed base plate, a cage, and an X-Y positioner that is adjustably mounted on the base plate. The cage is formed of a flat, thin, elongated arm and is secured at its rear end to the X-Y positioner. The forward end of the cage extends into a notched section that surrounds part of the slider. A stationary mounting block supports and retains the suspension in a fixed position relative to the slider. In another embodiment, the rear end of the cage is secured to the stationary mounting block and the X-Y positioner supports the suspension.
The testing method includes pre-wiring a slider and separately mounting the wired slider and a suspension into the test fixture. Adhesive is applied on either the slider or the suspension for establishing a temporary bond between the slider and the suspension. The suspension is then loaded onto and temporarily positioned relative to the slider. A magnetic disk is spun at a flying attitude over the slider, and the generated dynamic performance is analyzed. If the dynamic performance is not adequate, then the position of the slider is adjusted relative to the suspension. When performance is adequate, the adhesive is then fully cured.
REFERENCES:
patent: 4509251 (1985-04-01), Gyi et al.
patent: 4809427 (1989-03-01), Suzuki et al.
Darr Barry W.
Hunsaker Michael D.
Hall Carl E.
Kallman Nathan N.
Read Rite Corporation
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