Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
1997-06-11
2002-10-22
Vo, Peter (Department: 3729)
Metal working
Method of mechanical manufacture
Electrical device making
C029S603090, C029S593000, C324S210000, C324S212000, C324S760020
Reexamination Certificate
active
06467153
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to disk drive manufacturing methodology and more particularly to an improved method for manufacturing a disk drive wherein an integrated test system substantially reduces the labor involved in disk drive manufacturing and also substantially reduces the floor space required therefor. The improved method for manufacturing a disk drive also facilitates the application of statistical process control, so as to further enhance the efficiency of the manufacturing process.
BACKGROUND OF THE INVENTION
Magnetic disk drives, such as those used for mass storage in personal computer systems, are well known. Referring to
FIG. 14
, a disk drive
162
comprises a head disk assembly (HDA)
160
and a controller printed circuit board assembly (PCBA)
161
. The HDA
160
comprises a cover
166
, a base
167
, one or more disks
165
, a head stack assembly
163
for rotatably positioning a transducer
169
over a disk
165
, and a spindle motor
164
for spinning the disks
165
. The controller PCBA
161
comprises the electronic elements necessary to effect the writing of data upon the disks and the reading of data therefrom and for controlling the spindle motor
164
and the position of transducer
169
supported by head stack assembly
163
.
The manufacturing of a disk drive comprises the separate fabrication and preliminary testing of the HDA
160
and the controller PCBA
161
, which are subsequently mated and subjected to additional testing. This process is discussed in further detail below.
After HDA
160
has been fabricated, then servo writing is performed by securing HDA
160
to servowriter (not shown) in a well known process. During servo writing, servo information is written upon a surface of the disk
165
. The servo information facilitates the precise positioning of transducer
169
over disk
165
during read and write processes.
After servo writing has been accomplished, HDA
160
is tested to preliminarily verify the validity of the servo information written upon disk
165
. At this time an overlay is typically written to the disk to facilitate the later performance of an intelligent burn-in (IBI) test. A unique identification number is preferably also written to the disk at this time, so as to facilitate accurate tracking of the disk drive during the subsequent manufacturing processes. A bar code identification sticker may optionally be applied to HDA
160
as well.
Since the controller PCBA
161
has not yet been mated to the HDA
160
, the above processes are performed utilizing non-deliverable electronics, i.e., electronics which are part of the test apparatus and which remain with the test apparatus. Servo writing and servo validity testing are performed within a clean room since the hard disk has not yet been environmentally sealed.
As mentioned above, the controller PCBA
161
is manufactured and tested separately from the HDA
160
. Prior to leaving the clean room, the HDA
160
is environmentally sealed. Then typically outside the clean room, HDA
160
is mated to previously tested controller PCBA
161
so as to form a drive-under-test
162
.
After leaving the clean room, a plurality, typically twenty-four, of such drives-under-test
162
are then loaded onto a tray. The tray provides for the mechanical attachment and the electrical connection of the drives-under-test
162
thereto, so as to facilitate simultaneous testing thereof. Thus, each individual drive-under-test
162
is electrically connected to the tray, then the tray is electrically connected to a test apparatus.
Once connected to the test apparatus, a power-on test is performed and then each drive-under-test
162
is checked to verify that it is ready for operation. Next, the basic operation of the drive-under-test
162
is checked. This includes testing each drive-under-test
162
for the proper performance of basic writing, reading, and seeking operations. The power-on test, drive ready test, and basic operational tests are referred to collectively herein as the initial drive test (IDT).
After successfully passing the IDT, each drive-under-test
162
is subjected to an intelligent burn-in (IBI). The IBI is preferably performed within an environmental chamber so as to facilitate testing at different temperatures, such as at ambient temperature and at 40-50° C. The drive-under-test
162
test is conventionally performed by the drive as a stand-alone function, i.e. without connection to a host computer, because of its length and the relative scarcity of host connections available in prior art manufacturing installations. The IBI typically commences with a shortened version of the IDT, so as to verify basic functionality of the drive at both ambient and elevated temperatures. Next, a lengthy process comprising calibration of the drive and defect discovery and management is performed to set operating parameters and identify and map media defects which would affect the ability of the media to store information thereon reliably. Next, the drive-under-test
162
is formatted and the results of the IBI are stored thereon. Typically,
360
drives-under-test are subjected to the IBI simultaneously.
After successfully passing the IBI, each drive-under-test
162
is subjected to a final test. Final testing comprises connecting the drive-under-test
162
to a host computer, verifying operation of host commands, and analyzing the IBI test results and validating the same. Desired performance characteristics of the drive, such as head seek time, may be verified if desired. The IBI overlays are typically removed at this time, so as to prevent the drive from inadvertently being placed in the IBI mode by a customer. Any desired overlays, such as those required by a specific customer, for example, are written to the drive-under-test
162
.
Various other tests may be performed on an individual drive-under-test
162
during a debug process when a fault is found during routine testing. Such debug tests are performed to isolate the fault, so as to facilitate the correction thereof. For example, a drive-under-test
162
may fail the disk write portion of the IDT and then have the problem isolated to a particular head assembly during the debug process.
Although the above-described manufacturing procedure has been found generally suitable for the production of reliable disk drives, it does possess inherent deficiencies which detract from the overall desirability thereof. For example, the IDT, the IBI, and the final test are each performed at separate stations. The use of such separate stations inherently requires substantial handling of the disk drives to move them from one test station to another. It also requires substantial floor space within the manufacturing facility to accommodate the necessary test equipment.
As those skilled in the art will appreciate, the handling of disk drives as they are transported between test stations is undesirable since it inherently lengthens the time required for the manufacturing process and also since costly manpower is required to facilitate such handling. This is of particular concern since disk drives are frequently manufactured overseas in areas where unemployment is very low and thus such workers may be difficult to find or retain during periods of expansion. Further, handling inherently increases the risk of damage to disk drives. For example, the drives may be subjected to shock or electrostatic discharge (ESD) damage, connectors may be misaligned, etc., during such handling. Such damage frequently necessitates costly re-work of the disk drive, further undesirably increasing the cost of manufacture thereof.
As those skilled in the art will further appreciate, it is desirable to minimize the amount of floor space required for any particular process within a manufacturing facility, so as to decrease the costs associated therewith. Such costs include the acquisition or lease cost of the space itself, as well as the cost of heating, cooling, cleaning, etc. associated with such space. Additionally, floor space is frequently the lim
Butts William Orson
Pakzad Mostafa
Sarraf Mohammad
Shara, Esq. Milad G
Tugbong A. Dexter
Vo Peter
Western Digital Technologies Inc.
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