Spindle motor fixture for outgassing system

An apparatus for retaining a spindle motor during an outgassing test includes a body formed from an inert material and having an interior chamber for receiving a base of the spindle motor. Fasteners secure the spindle motor to the body to seal the interior chamber and prevent the spindle motor base from outgassing any compounds during the outgassing test. An electrical pad attached within the interior chamber contacts an electrical connector on the base of the spindle motor. An electrical wire attaches the electrical pad to a combination power source and motor controller for operating the spindle motor. The body and the attached spindle motor are placed within a test container and the electrical wire is passed through both the body and the test container for attachment to the power source and motor controller. The electrical wire includes an inert coating to prevent the electrical wire from impacting the results of the outgassing test.

FIELD OF THE INVENTION 
The present invention relates to collecting chemicals and chemical 
compounds outgassed by a disc drive spindle motor. More particularly, the 
present invention relates to a system for collecting outgassed compounds 
by fixing the spindle motor within a testing container so that only a 
portion of the motor is exposed to the interior of the container and so 
that the motor may be operated within the testing container in a manner 
representative of operation within a disc drive. 
BACKGROUND OF THE INVENTION 
It is well known that complex electromechanical devices, such as computer 
disc drives, can be harmed by foreign substances which come into contact 
with vital components of the device. For example, dirt or dust particles 
which accumulate on the platters of a disc drive can damage the read/write 
head of the drive causing a "crash." Thus, such devices are typically 
manufactured within a clean room environment and are sealed prior to 
leaving the clean room to reduce or prevent the possibility of such 
contamination. 
However, the current breed of disc drives spin much faster and are more 
densely packed with data than prior drives. These speed and size increases 
require that the read/write heads fly very close to the surface of the 
disc platters (on the order of a micron). In light of these very low fly 
heights, it is possible for matter smaller than common dust or smoke 
particles to cause head/disc crashes. Indeed, even chemicals or chemical 
compounds which are outgassed by the different components of the disc 
drive may be sufficiently large to interfere with the drive heads. 
Although some disc drive components outgas chemicals and chemical compounds 
while the drive is inactive, the level of outgassing typically increases 
when the drive is operating and the components are exposed to high 
temperatures. These outgassed chemicals and chemical compounds are easily 
transported throughout the drive (due to the rotation of the disc platters 
and the resulting air currents within the drive) where they typically bond 
to the substrate that coats the disc platters. In addition to physically 
interfering with the drive heads during operation of the drive, some 
aggressive outgassed compounds (e.g., adhesives) may react chemically with 
the drive heads during periods of inactivity when the heads are in direct 
contact with the disc platters. Such chemical reactions cause stiction 
between the heads and the disc platters which further contributes to early 
disc drive failure. 
Thus, it is important for disc drive manufacturers to carefully inspect all 
of the components which make up the drive for the presence of outgassed 
compounds. Examples of such components within a disc drive include voice 
coil motors, coil bobbins, magnets, read/write heads, adhesives and 
labels. One specific disc drive component that may contribute greatly to 
the total outgassing of a disc drive is the spindle motor. 
FIG. 1 illustrates a typical prior art spindle motor 20. The motor 20 
includes a base 22 which is fixed to a base plate 24 (FIG. 2) of a disc 
drive 26. A hub 28 (FIG. 1) of the spindle motor 20 rotates on a bearing 
(not shown) about a shaft 30 connected to the base 22. In this manner, the 
hub 28 is free to rotate in relation to the base 22 of the spindle motor 
20. The base 22 typically includes electrical windings (not shown) while 
the hub 28 typically includes magnets (not shown) which interact with the 
magnetic field created when an electrical current passes through the 
windings (not shown) within the base 22. Thus, the base 22 acts as a 
stator while the hub 28 acts as a rotor of the spindle motor 20. 
One or more disc platters 32 (FIG. 2) are attached to rotate with the hub 
28 about the fixed shaft 30. A separate voice coil motor 34 operates to 
move one or more arms 36 over the spinning disc platters 32 so that 
magnetic read/write heads 38 can access any part of the disc platters 32. 
In current disc drives, the spindle motor 20 may be required to spin at 
speeds up to 10,000 revolutions per minute (RPM). This high speed 
operation, together with the large number of components which make up a 
spindle motor (e.g., magnets, wiring, bearings, adhesive seals, etc.), 
causes the spindle motor 20 to outgas a variety of compounds. Although the 
spindle motor 20 outgasses compounds even when the motor 20 is idle, the 
outgassing levels increase dramatically during operation of the spindle 
motor. Specifically, many of the components within the spindle motor 20 
may outgas compounds which are normally retained within the motor 20 while 
the motor is at rest. However, when the motor 20 spins up to an operating 
speed of 5,000 to 10,000 RPM, centrifugal force tends to expel these 
compounds from the interior of the motor 20 to the interior of the drive 
26. 
Unfortunately, prior outgassing test systems typically test the spindle 
motor in an idle or non-operative state. Specifically, one type of 
outgassing test, hereafter referred to as "static headspace sampling," 
entails placing a component (such as the idle spindle motor 20 shown in 
FIG. 1) within a sealed container and holding the component at an elevated 
temperature until the outgassed compounds reach a state of equilibrium 
within the headspace. The term "headspace" is utilized herein to refer to 
the space within the sealed container which is not taken up by the tested 
component itself. The sealed container typically includes an open top 
sealed by a septum to allow a needle to penetrate the headspace and 
withdraw a sample of the equilibrated headspace. This sample is then 
analyzed using known techniques and equipment such as a gas chromatograph 
and a mass spectrometer to determine the composition of the different 
outgassed compounds. However, while testing the spindle motor 20 at an 
elevated temperature may simulate the heat which is generated by an 
operating spindle motor 20, any additional compounds outgassed at the 
elevated temperatures will likely remain confined within the interior of 
the non-operative motor itself. 
One alternative to the static headspace sampling test entails placing the 
component to be tested within a test container and then passing an inert 
gas through the container during the course of the test to continuously 
flush outgassed compounds from the container. This is referred to as a 
dynamic headspace outgassing test. However, the dynamic gas flow applied 
to the test container during the dynamic headspace outgassing test is not 
typically strong enough to expel outgassed compounds from the confines of 
the idle spindle motor 20. Thus, regardless of whether a static or a 
dynamic outgassing procedure is used to test the spindle motor 20, neither 
test provides a sufficiently accurate or representative indication of the 
types and amounts of outgassed compounds which an operative (i.e., 
spinning) spindle motor 20 produces and expels within the interior of a 
functioning disc drive 26. 
A further concern with prior art spindle motor outgassing tests is that the 
entire spindle motor 20 (FIG. 1) is typically placed within the testing 
container (regardless of whether the container is used in a static or a 
dynamic testing system). However, FIGS. 2 and 3 illustrate that only a 
portion of the spindle motor 20 is exposed to the interior of the disc 
drive 26 so that testing the entire spindle motor 20 may lead to the 
detection of outgassed compounds which would not normally be found within 
the interior of the drive 26 (i.e., a false positive reading). 
FIG. 2 illustrates an exploded view of a disc drive 26 showing the base 
plate 24 of the drive together with a top cover 40 and a printed circuit 
board assembly (PCBA) 42 which are attached to opposite sides of the base 
plate 24. The top cover 40 fits over the voice coil motor 34, the arms 36, 
the disc platter(s) 32 and the spindle motor 20 to form a substantially 
sealed interior volume of the disc drive 26. The disc platters 32 are cut 
away in FIG. 2 to better illustrate the spindle motor 20 mounted to the 
disc drive base plate 24. The base plate 24 includes an opening (not 
shown) for receiving the base 22 of the spindle motor while an outwardly 
protruding annular flange 46 of the base 22 (best shown in FIG. 1) is 
preferably attached to a top surface 48 of the disc drive base plate 24 by 
a plurality of screws 50. Attached in this manner, the base 22 of the 
spindle motor 20 extends below the base plate 24 of the disc drive, as 
shown in FIG. 3, and thus is not exposed to the interior volume of the 
disc drive 26. 
One significant element of the spindle motor 20 which extends below the 
base plate 24 of the disc drive 26 is the electrical connector 52 (FIG. 1) 
which provides power for operating the spindle motor 20. Specifically, the 
electrical connector 52 is attached to a lower portion of the spindle 
motor base 22 so that a number of electrical leads 54 extend radially 
outwardly from the base 22 below the annular flange 46. The electrical 
leads 54 are positioned to contact matching electrical pads 56 (FIG. 2) on 
a top surface 58 of the PCBA 42 as the base 22 of the spindle motor 20 
extends through a circular opening 60 formed in the PCBA 42. The 
electrical pads 56 supply power to the connector 52 for operating the 
spindle motor 20 once the PCBA 42 is connected to a power supply/motor 
controller (not shown). Furthermore, the connector 52 is typically 
attached to the spindle motor base 22 by an adhesive material, and the 
presence of the connector 52 and the adhesive material within the prior 
art testing container frequently contributes false positive readings to 
prior art outgassing tests. 
Thus, prior art outgassing tests of disc drive spindle motors produce 
inaccurate or unrepresentative results for two primary reasons. First, the 
motors are typically tested in an idle state where the hub or "rotor" 28 
is not rotating so that outgassed compounds within the motor 20 are not 
expelled into the headspace of the testing container. Second, the motors 
are typically tested as a whole so that the outgassing results include 
contributions from components of the motor 26 which are not typically 
exposed to the interior volume of the disc drive 26. 
It is with respect to these and other background considerations, 
limitations and problems that the present invention has evolved. 
SUMMARY OF THE INVENTION 
The present invention relates to a system for fixing a spindle motor within 
a testing container so that only a portion of the spindle motor is exposed 
to the interior of the testing container and, in one embodiment, to 
operate the spindle motor within the testing container in a manner 
representative of operation within a disc drive. 
In accordance with one embodiment of the present invention, an apparatus is 
provided for retaining a spindle motor during an outgassing test. The 
spindle motor typically includes an annular base and a hub adapted to 
rotate relative to the annular base. The apparatus includes a body with an 
interior chamber for receiving the annular base of the spindle motor. Once 
the spindle motor base has been inserted within the interior chamber, 
fasteners secure the spindle motor to the body and form a substantially 
airtight seal within the interior chamber to prevent the spindle motor 
base from outgassing any compounds during the outgassing test. The body 
may be formed from an inert material to prevent the body from impacting 
the results of the outgassing test. 
In another embodiment of the present invention, the apparatus further 
includes an electrical pad attached within the interior chamber for 
contacting an electrical connector on the base of the spindle motor. An 
electrical wire is attached at one end to the electrical pad within the 
interior chamber and extends outside of the interior chamber to connect 
the electrical pad to a combination power source and motor controller for 
operating the spindle motor. 
The present invention can also be implemented as an apparatus for 
collecting outgassed compounds from a spindle motor. One embodiment of the 
apparatus including a body formed from an inert material and defining an 
interior chamber for receiving the annular base of the spindle motor. Once 
the spindle motor base has been inserted within the interior chamber, 
fasteners secure the spindle motor to the body and form a substantially 
airtight seal within the interior chamber. A test container defines an 
interior volume for receiving both the body and the attached spindle 
motor, and the airtight seal prevents the spindle motor base from 
outgassing any compounds within the interior volume of the test container. 
The body may be formed from an inert material to prevent the body from 
outgassing any compounds, as well as to prevent the body from reacting 
with any compounds outgassed by the spindle motor, within the test 
container. 
In another embodiment of the present invention, the apparatus further 
includes an electrical pad attached within the interior chamber for 
contacting an electrical connector on the base of the spindle motor. An 
electrical wire is attached at one end to the electrical pad within the 
interior chamber and extends outside of the interior chamber of the body 
and outside of the interior volume of the test container to connect the 
electrical pad to a combination power source and motor controller for 
operating the spindle motor. 
The present invention can further be implemented as an apparatus for 
collecting outgassed compounds from a spindle motor including a test 
container and means for retaining the spindle motor in the test container 
and for preventing the annular base and the electrical connector from 
outgassing compounds within the test container. In another embodiment of 
the present invention, the apparatus further includes means for providing 
power to the spindle motor to operate the spindle motor within the test 
container.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 4 illustrates a preferred embodiment of a spindle motor fixture 70 of 
the present invention. The spindle motor fixture 70 is adapted to 
accommodate a spindle motor 20, as shown in FIG. 1, and to provide power 
to the electrical connector 52 on the motor 20 to allow operation of the 
motor 20 during an outgassing test. The base 22 of the spindle motor 20 is 
recessed within the spindle motor fixture 70 as described below (FIGS. 
7-9) to simulate the actual portion of the spindle motor 20 which is 
exposed within the disc drive 26 (see FIGS. 2 and 3). 
Although the preferred embodiment of the spindle motor fixture 70 is 
illustrated for use with a particular dynamic headspace outgassing system 
illustrated in FIGS. 8-10, it is understood that the spindle motor fixture 
70 may be beneficially used with other types of outgassing systems, 
including the static headspace sampling system described above. That is, 
any outgassing system which normally tests a spindle motor in an idle or 
non-operative state would benefit from using the spindle motor fixture 70 
to improve the accuracy of the outgassing test results. Thus, the 
illustration and following description of the use of the preferred 
embodiment of the spindle motor fixture 70 with the dynamic headspace 
outgassing system of parent U.S. patent application Ser. No. 09/315,310 
should not be viewed as a limitation on the present invention. 
The spindle motor fixture 70 preferably includes a substantially 
cylindrical body 72 formed from an inert material such as Teflon. The 
cylindrical body 72 includes an outer surface 74, a top end 76 and a 
bottom end 78. A bore formed from the top end 76 of the body 72 defines an 
interior chamber 80 for receiving the base 22 of the spindle motor 20. The 
interior chamber 80 is open at the top end 76 and is bounded by a 
cylindrical interior wall 82 and an interior bottom surface 84. 
An annular rim 86 (FIG. 4) surrounds the open top end 76 of the chamber 80, 
while an exterior bottom surface 88 (FIGS. 5 and 6) of the Teflon body 72 
preferably includes an annular groove 90 (FIG. 5) formed therein to 
underlie the annular rim 86 at the top of the body 72. A plurality of 
through holes 92 (FIGS. 4-6) are preferably formed lengthwise between the 
annular rim 86 and the annular groove 90 of the body 72. The holes 92 are 
spaced equidistantly around the rim 86 as shown in FIG. 4 and are 
preferably aligned with holes 94 formed in the annular flange 46 of the 
spindle motor 20 to allow mounting screws 96 to attach the spindle motor 
20 onto the spindle motor fixture 70, as described below. 
Due to the malleable nature of Teflon, and particularly the tendency of 
Teflon to change shape when heated, the spindle motor fixture 70 includes 
a separate mounting ring 100 (FIG. 7) for anchoring the mounting screws 
96. The mounting ring 100 is preferably formed from stainless steel and 
includes an annular base 102 and three cylindrical posts 104 extending 
vertically upward from the annular base 102. The three cylindrical posts 
104 are spaced equidistantly about the annular base 102 and are preferably 
aligned with the through holes 92 formed in the body 72 of the spindle 
motor fixture 70. An outer diameter of the cylindrical posts 104 is 
substantially equal to a diameter of the through holes 92 so that the 
posts 104 of the mounting ring 100 may be inserted into the through holes 
92 from the bottom end 78 of the Teflon body 72, as shown in FIG. 7. An 
interior surface 106 (FIG. 5) of each cylindrical post 104 is threaded to 
receive an end of the mounting screws 96. 
The annular base 102 of the mounting ring 100 is preferably dimensioned to 
fit flush within the annular groove 90 on the bottom surface 88 of the 
body so that the annular base 102 is effectively recessed within the 
exterior bottom surface 88, as shown in FIG. 5. Recessing the stainless 
steel mounting ring 100 in this manner is important for minimizing 
possible sources of contamination during the outgassing test, as described 
below. 
Although the base 22 of the spindle motor 20 is substantially cylindrical 
in shape as shown in FIGS. 1 and 3, the electrical connector 52 protrudes 
radially outward from the base 22 as shown in FIG. 1. Thus, the interior 
chamber 80 of the spindle motor fixture 70 preferably includes a cut-out 
or notched region 110 (FIGS. 4 and 5) to accommodate the protruding 
electrical connector 52. The notched region 110 preferably extends from 
the annular rim 86 and proceeds down the cylindrical inner surface 82 of 
the chamber 80 as shown in FIGS. 4 and 5. A bottom portion of the notched 
region 110 preferably widens into a horizontal ledge 111 for supporting a 
plurality of electrical pads 112 adapted to engage the electrical leads 54 
on the spindle motor electrical connector 52. In the preferred embodiment 
shown in FIGS. 4 and 5, the pads 112 are fixed to a small circuit board 
114 which, in turn, fits atop the widened horizontal ledge 111 at the 
bottom of the notched region 110. Of course, one skilled in the art may 
conceive of alternative means for securing the electrical pads 112 within 
the cut-out or notched region 110 to ensure secure contact between the 
pads 112 and the leads 54 of the spindle motor connector 52. 
In essence, the electrical pads 112 (FIGS. 4 and 5) simulate the pads 56 
(FIG. 2) on the PCBA 42 which normally contact the leads 54 of the 
connector 52 when the spindle motor 20 is installed within a disc drive 
26. Electrical wires 116 (FIGS. 4 and 5) attached to each pad 112 are 
connected to a power supply/motor controller 120 (FIG. 10) as described in 
greater detail below. The electrical wires 116 preferably extend along the 
interior bottom surface 84 of the chamber 80 where they pass through an 
opening 122 formed between the inner surface 82 and the outer surface 74 
of the body 72 of the spindle motor fixture 70. The wires 116 are 
preferably surrounded by a Teflon sheath 124 (FIG. 4) so that only the 
Teflon material and not the wires 116 themselves are exposed to the 
environment outside of the chamber 80. 
FIG. 7 illustrates the attachment of the spindle motor 20 to the spindle 
motor fixture 70. The base 22 of the motor 20 is first inserted within the 
chamber 80 of the motor fixture 70 so that the electrical connector 52 is 
aligned with the notched region 110. The base 22 is lowered into the 
chamber 80 until the annular flange 46 surrounding the base 22 contacts 
the annular rim 86 at the top end 76 of the fixture 70. The depth of the 
horizontal ledge 111 along the notched region 110 of the chamber 80 
preferably positions the small circuit board 114 so that the electrical 
pads 112 contact the electrical leads 54 of the connector 52 once the 
annular flange 46 contacts the annular rim 86. Once positioned as 
described above, the mounting screws 96 are inserted through both the 
holes 94 in the annular flange 46 of the motor 20 as well as the holes 92 
formed in the Teflon body 72 of the spindle motor fixture 70. The ends of 
the mounting screws 96 are received within the cylindrical threaded posts 
104 so that tightening the screws 96 causes the motor 20 and the stainless 
steel mounting ring 100 to be drawn together. Thus, tightening the screws 
96 produces two beneficial results. First, the mounting ring 100 is drawn 
upward to the maximum extent possible to ensure the ring 100 is recessed 
within the annular groove 90 in the bottom surface 88 of the fixture 70. 
Second, the annular flange 46 on the spindle motor is forced down to bear 
against the relatively soft annular rim 86, thereby forming a 
substantially airtight seal around the interior chamber 80. Although the 
chamber 80 does include the opening 122 for allowing the electrical wires 
116 to pass outside of the chamber 80, the Teflon sheath 124 surrounding 
the wires 116 helps to seal the opening 122, thereby maintaining a 
substantially airtight seal within the chamber 80. 
Thus, the assembly of the spindle motor 20 with the spindle motor fixture 
70 serves to conceal the base 22 and the connector 52 of the spindle motor 
20 within the substantially airtight chamber 80 of the fixture 70. In this 
manner, the spindle motor fixture 70 accurately simulates the connection 
of the spindle motor 20 within a disc drive 26 since the same portion of 
the motor 20 is exposed in both instances. Furthermore, the use of Teflon 
to both form the body 72 of the spindle motor fixture 70 and to form the 
sheath 124 for wrapping the electrical wires 116 ensures that the fixture 
70 itself will not contaminate the outgassing test since Teflon is 
substantially inert even at the elevated temperatures typically used for 
outgassing tests. Of course, while Teflon is described as the preferred 
material for both the fixture body 72 and the electrical wire sheath 124, 
one skilled in the art may utilize other substantially inert materials in 
place of Teflon. 
Once the spindle motor 20 and the spindle motor fixture 70 are assembled as 
shown in FIG. 7, the combination motor 20 and fixture 70 is preferably 
inserted within a testing container for the purposes of conducting an 
outgassing test. One preferred use of the spindle motor fixture 70 to test 
a spindle motor 20 is with the dynamic headspace outgassing system 
illustrated in FIGS. 8-10 and described in greater detail in parent U.S. 
patent application Ser. No. 09/315,310, entitled DYNAMIC HEADSE 
OUTGASSING SYSTEM, filed May 20, 1999, and assigned to the assignee of the 
present invention, the disclosure of which is hereby incorporated by this 
reference. 
FIGS. 8 and 9 illustrate the spindle motor fixture 70 and the attached 
spindle motor 20 inserted within a chamber 130 of a Teflon test container 
132. The Teflon container 132 essentially comprises an open cylinder 
similar to but larger than the body 72 of the spindle motor fixture 70 
itself. A Teflon top or lid 134 is used to seal the open top of the 
container 132 once the spindle motor fixture 70 and the attached spindle 
motor 20 have been inserted within the chamber 130, as shown in FIG. 9. A 
plurality of threaded rods 136 (FIG. 9) preferably run vertically through 
the through the container 132 and attach to a steel plate 138 to the 
bottom of the Teflon container 132. Upper ends of the threaded rods 136 
extend through openings (not shown) formed in the Teflon top 134 and 
through additional aligned openings (not shown) in an upper steel plate 
140. Thumb nuts 142 are then threaded onto the rods 136 to bear against 
the upper steel plate 140 and compress the Teflon top 134 against the open 
upper end of the Teflon test container 132. An o-ring 144 (FIG. 9) works 
in conjunction with the relatively malleable Teflon material to ensure an 
airtight seal between the top 134 and the container 132 once the spindle 
motor fixture 70 and spindle motor 20 have been inserted within the 
chamber 130. 
Prior to sealing the spindle motor fixture 70 within the chamber 130, the 
Teflon sheath 124 surrounding the electrical wires 116 is preferably 
threaded through an opening (not shown) in the Teflon top 134 and a second 
opening 148 in the upper steel plate 140, as shown in FIG. 9. The 
electrical wires 116 are then attached to a power supply/motor controller 
120 (FIG. 10), as described in greater detail below. It is preferred that 
a single Teflon top 134 is matched with a particular spindle motor fixture 
70 so that the electrical wires 116 and the Teflon sheath 124 can be 
carefully fitted through the Teflon top 134 in a manner which does not 
degrade the airtight seal within the chamber 130. Thus, the top 134 is 
specifically used with the container 132 for testing spindle motors 20 
with the spindle motor fixture 70, although another Teflon top (without an 
opening for the wire sheath 124) may be used with the same container 132 
for conducting outgassing tests of other (non-powered) disc drive 
components. 
The outgassing container 132 and top 134 preferably include gas inflow and 
outflow connectors 150 and 152, respectively. The connectors 150 and 152 
each include a threaded end (not shown) which preferably mates with a 
threaded bushing 154 set within the Teflon material of the container 132 
and the top 134. The bushings 154 thus hold the connectors 150 and 152 in 
fluid communication with a small opening formed through the respective 
wall of the container 132 and the top 134 to provide access to the 
interior chamber 130. Additional details regarding the container 132, the 
top 134 and the connectors 150 and 152 may be found in parent U.S. patent 
application Ser. No. 09/315,310, although the present invention is not 
limited to use with the outgas testing container disclosed therein. 
One preferred system for conducting the outgassing test of the spindle 
motor 20 is shown in FIG. 10. The testing container 132 with the spindle 
motor fixture 70 and attached motor 20 placed therein is preferably placed 
within a laboratory oven 160 to maintain the test chamber 130 at a 
predetermined temperature during the course of the outgassing test. A gas 
inflow line 162 is connected between the inflow connector 150 and a source 
164 of inert gas such as a source of substantially pure Nitrogen gas. 
Similarly, a gas outflow line 166 is attached between the outflow 
connector 152 on the container and a trap 168 on the exterior of the oven 
160. The trap 168 preferably comprises a hollow tube filled with an 
absorbent such as activated carbon which bonds with any outgassed 
compounds expelled from the chamber 130 while allowing the inert Nitrogen 
gas to pass through the tube to the atmosphere. 
The outgassing test is conducted by flowing the inert gas through the 
chamber 130 at a predetermined flow rate for a predetermined time. For 
example, a flow rate of 50 milliliters/minute for a three-hour test period 
at an oven temperature of 85 degrees Celsius has been found to provide 
consistent and repeatable test results. At the conclusion of the 
outgassing test, the contents of the carbon trap 168 are desorbed and 
analyzed with standard equipment such as a gas chromatograph and a mass 
spectrometer to determine the composition of the outgassed chemicals and 
compounds. 
Regardless of the specific outgas testing system which is utilized (e.g., 
static or dynamic), the spindle motor fixture 70 ensures that only the 
desired, representative portion of the spindle motor 20 will be exposed 
within the test chamber. Using the example of the testing container 132 in 
FIG. 8, the inert gas flowing through the chamber 130 is exposed to only 
inert materials (e.g., the Teflon container 132 and top 134, the Teflon 
body 72 of the fixture 70, and the Teflon wire sheath 124) and to the same 
upper portion of the motor 20 which is exposed within the disc drive 26 
(FIG. 2). Thus, even if the spindle motor 20 is tested in an idle or 
non-operative state, the ability of the fixture 70 to conceal the base 22 
and the electrical connector 52 of the spindle motor enhances the accuracy 
and representative nature of the results in comparison with prior 
outgassing tests that place the entire spindle motor 20 in the test 
container. However, another important benefit of the present invention is 
the ability to operate the spindle motor 20 during the outgassing test, as 
described below. 
The electrical wires 116 connect the spindle motor 20 to a power 
supply/motor controller 120 which is located outside of the oven 160, as 
shown in FIG. 10. The power supply/motor controller 120 supplies the 
necessary power to spin the "rotor" or hub 28 of the spindle motor 20 at a 
predetermined rotational velocity. For example, current disc drives 
typically utilize spindle motor speeds of 5,400, 7,200 or 10,000 RPM. 
Thus, the power supply/motor controller 120 is preferably capable of 
supplying the proper power and control signals to the spindle motor 20 to 
achieve the desired spin rate. Furthermore, the motor controller 120 is 
preferably specially programmed with "run only" code to allow the motor 
hub 28 to spin continuously during the multi-hour test without timing out 
and stopping prior to the end of the test. 
The spindle motor fixture 70 thus allows the spindle motor 20 to be 
operated in a normal matter during the course of the outgassing test. As 
described above, operation of the spindle motor 20 provides added benefits 
over simply heating the motor to simulate the operating temperature of the 
motor 20. Although it is still desirable to place the test container 132 
within the oven 160 to simulate the elevated temperature that the disc 
drive 26 experiences within a computer environment, simply heating the 
motor 20 can not simulate the centrifugal forces experienced by the motor 
during operation at high spin rates. Indeed, the following table 
demonstrates the outgassing results for three different tests of a spindle 
motor. The three columns of data provide dynamic headspace outgassing data 
(in nanograms) for testing (1) the entire spindle motor 20 in an idle 
state (i.e., the prior art method); (2) only the top portion of the idle 
spindle motor 20 using the spindle motor fixture 70; and (3) only the top 
portion of the operating spindle motor using the spindle motor fixture 70 
and a power supply/motor controller 120 that spins the motor hub 28 at a 
rate of 5,400 RPM. All tests were run over a three hour period at an oven 
temperature of 85 degrees Celsius, and each column represents the average 
of at least three test runs. 
______________________________________ 
Top Portion 
Top Portion 
Only of Idle 
Only of 
Spindle Running 
Entire Spindle 
Motor (With 
Spindle Motor 
Motor (Without 
the Spindle 
(With the 
the Spindle 
Motor Spindle Motor 
Motor Fixture) 
Fixture) Fixture) 
Compound Name 
(nanograms) 
(nanograms) 
(nanograms) 
______________________________________ 
Glycol Dimethacryl- 
0 0 451 
ates (TGDMA) 
Hydroxyalkyl 10,404 11,459 12,830 
Methacrylates (HEMA) 
Acrylate Esters (HEA) 
949 760 1,007 
Dimethly Benzene 
4,672 4,116 7,627 
Methanol 
Tributyl Amine 
150 118 173 
Derivatives (TBA) 
Acetophenone (CHAP, 
949 644 1,070 
DMAP, etc.) 
Acrylic Acids (other 
0 120 58 
than EHA) 
Organic Acids 
0 21 136 
BHT 456 616 1,466 
Styrene & derivatives 
1,437 965 1,311 
Hydrocarbons, others 
27,333 16,619 23,344 
Totals 46,350 35,439 49,475 
______________________________________ 
Note: a value of 0 is below the threshold limit of the test equipment. 
Thus, the trend from the above table demonstrates that an entire idle 
spindle motor 20 will outgas more compounds than an idle spindle motor 
that is partially concealed within a spindle motor fixture 70. Likewise, 
an operating spindle motor 20 will typically outgas more compounds than an 
idle spindle motor 20 when both are fitted within the fixture 70. This is 
particularly true of the more aggressive compounds such as Glycol 
Dimethacrylates (TGDMA), acrylic esters (HEA), BHT and acetophenones such 
as DMAP. It is aggressive compounds such as these that drive manufacturers 
are primarily concerned about since these compounds are most likely to 
cause a head disc crash. 
The spindle motor fixture 70 thus enhances the ability to perform 
outgassing tests on spindle motors 20 by accurately simulating the 
environment to which the spindle motor 20 is exposed within a disc drive 
26. The inert material (preferably Teflon) which comprises the forms the 
interior chamber 80 of the fixture 70 prevents the fixture 70 from 
outgassing any compounds of its own during the test and further prevents 
the fixture 70 from reacting with any compounds outgassed by the spindle 
motor 20. Indeed, even the stainless steel mounting ring 100 is preferably 
recessed within the exterior bottom surface 88 of the fixture 70 to 
prevent the ring 100 from being exposed to the interior of the test 
chamber 130. 
While the spindle motor fixture 70 is shown in one preferred embodiment 
with the dynamic headspace outgassing system described in the parent 
application, it is understood that the benefits of the fixture 70 (i.e., 
increase accuracy of the test results) may be realized with any outgassing 
system that is capable of testing spindle motors 20 in their entirety. 
In summary, the preferred embodiment exemplary of the invention and 
disclosed herein is directed to an apparatus (such as 70) for retaining a 
spindle motor (such as 20) during an outgassing test, the spindle motor 
including an annular base (such as 22) and a hub (such as 28) adapted to 
rotate relative to the annular base (such as 22). The apparatus (such as 
70) includes a body (such as 72) defining an interior chamber (such as 80) 
adapted to receive the annular base (such as 22), the body (such as 72) 
further defining an annular rim (such as 86) surrounding an open upper end 
of the interior chamber (such as 80). Fasteners (such as 96) are adapted 
to secure the spindle motor (such as 20) to the annular rim (such as 86) 
to form a substantially airtight seal within the interior chamber (such as 
80). 
In another preferred embodiment of the present invention, the body (such as 
72) is formed from an inert material such as Teflon. 
In another preferred embodiment of the present invention, the annular base 
(such as 22) of the spindle motor (such as 20) includes a protruding 
annular flange (such as 46) having holes (such as 94) formed therein. The 
annular rim (such as 86) also includes holes (such as 92) aligned with the 
holes (such as 94) in the annular flange (such as 46) for receiving the 
fasteners (such as 96). 
In another preferred embodiment of the present invention, the holes (such 
as 92) in the annular rim (such as 86) extend through the body (such as 
72) to a bottom surface (such as 88) of the body. An annular ring (such as 
100) attached to the bottom surface (such as 88) of the body (such as 72) 
below the annular rim (such as 86) includes a base (such as 102) and posts 
(such as 104) extending vertically upward from the base (such as 102) 
through the holes (such as 92) in the body (such as 72) to act as anchors 
for the fasteners (such as 96). 
In another preferred embodiment of the present invention, the annular ring 
base (such as 102) and the posts (such as 104) are formed from stainless 
steel. Each post (such as 104) includes a hollow threaded interior (such 
as 106) to receive an end of one of the fasteners (such as 96). 
In another preferred embodiment of the present invention, the bottom 
surface (such as 88) of the body (such as 72) includes an annular groove 
(such as 90). The annular ring base (such as 102) is fitted within the 
annular groove (such as 90) to recess the annular ring base (such as 102) 
within the bottom surface (such as 88) of the body (such as 72). 
In another preferred embodiment of the present invention, the spindle motor 
(such as 20) includes an electrical connector (such as 52) attached to the 
annular base (such as 22) of the spindle motor. An electrical pad (such as 
112) is attached within the interior chamber (such as 80) for contacting 
the electrical connector (such as 52). An electrical wire (such as 116) is 
attached at one end to the electrical pad (such as 112), and a second end 
of the electrical wire (such as 116) extends outside of the interior 
chamber (such as 80) through an opening (such as 122) formed in the body 
(such as 72). 
In another preferred embodiment of the present invention, a sheath (such as 
124) formed from an inert material such as Teflon covers a portion of the 
electrical wire (such as 116) extending outside of the interior chamber 
(such as 80). 
In another preferred embodiment of the present invention, the electrical 
connector (such as 52) is attached to an outer surface of the annular base 
(such as 22) of the spindle motor (such as 20). The body (such as 72) 
defines a notched region (such as 110) within the interior chamber (such 
as 80). The notched region (such as 110) extends to the annular rim (such 
as 86) and is adapted to receive the electrical connector (such as 52) 
when the annular base (such as 22) of the spindle motor (such as 20) is 
inserted within the interior chamber (such as 80). The electrical pad 
(such as 112) is located within the notched region (such as 110). 
In another preferred embodiment of the present invention, the electrical 
pad (such as 112) is fixed to a circuit board (such as 114), and the 
circuit board is attached within a bottom portion of the notched region 
(such as 110). 
A further preferred embodiment of the present invention includes apparatus 
for collecting outgassed compounds from a spindle motor (such as 20), the 
spindle motor including an annular base (such as 22) and a hub (such as 
28) adapted to rotate relative to the annular base (such as 22). The 
apparatus includes a body (such as 72) defining an interior chamber (such 
as 80) adapted to receive the annular base (such as 22), the body (such as 
72) formed from an inert material and further defining an annular rim 
(such as 86) surrounding an open upper end of the interior chamber (such 
as 80). Fasteners (such as 96) are adapted to secure the spindle motor 
(such as 20) to the annular rim (such as 86) to form a substantially 
airtight seal within the interior chamber (such as 80). A test container 
(such as 132) defines an interior volume (such as 130) to receive the body 
(such as 72) and the spindle motor (such as 20). 
In another preferred embodiment of the present invention, the spindle motor 
(such as 20) includes an electrical connector (such as 52) attached to the 
annular base (such as 22) of the spindle motor. An electrical pad (such as 
112) attached within the interior chamber (such as 80) contacts the 
electrical connector (such as 52). An electrical wire (such as 116) 
attached at one end to the electrical pad (such as 112). A second end of 
the electrical wire (such as 116) extends outside of the interior chamber 
(such as 80) of the body (such as 72) through an opening (such as 122) 
formed in the body (such as 72) and outside of the interior volume (such 
as 130) of the test container (such as 132) through an opening formed in 
the test container. 
In another preferred embodiment of the present invention, a combination 
power source and motor controller (such as 120) attached to the second end 
of the electrical wire (such as 116) operates the spindle motor (such as 
20). 
In another preferred embodiment of the present invention, a sheath (such as 
124) formed from an inert material covers a portion of the electrical wire 
(such as 116) extending outside of the interior chamber (such as 80) of 
the body (such as 72) and inside the interior volume (such as 130) of the 
test container (such as 132). 
In another preferred embodiment of the present invention, the electrical 
connector (such as 52) is attached to an outer surface of the annular base 
(such as 22) of the spindle motor (such as 20). The body (such as 72) 
defines a notched region (such as 110) within the interior chamber (such 
as 80). The notched region (such as 110) extends to the annular rim (such 
as 86) and is adapted to receive the electrical connector (such as 52) 
when the annular base (such as 22) of the spindle motor (such as 20) is 
inserted within the interior chamber (such as 80). The electrical pad 
(such as 112) is located within the notched region (such as 110). 
In another preferred embodiment of the present invention, a bottom surface 
(such as 88) of the body (such as 72) includes an annular groove (such as 
90) positioned below the annular rim (such as 86). A stainless steel 
annular ring (such as 100) is fitted within the annular groove (such as 
90), and the annular ring (such as 100) includes posts (such as 104) 
extending vertically upward through the body (such as 72) to act as 
anchors for the fasteners (such as 96). 
A further preferred embodiment of the present invention includes apparatus 
for collecting outgassed compounds from a spindle motor (such as 20), the 
spindle motor having an annular base (such as 22) and a hub (such as 28) 
adapted to rotate relative to the annular base. The apparatus includes a 
test container (such as 132) and means for retaining the spindle motor 
(such as 20) in the test container (such as 132) and for preventing the 
annular base (such as 22) from outgassing compounds within the test 
container (such as 132). 
In another preferred embodiment of the present invention, the apparatus 
includes means for providing power to the spindle motor (such as 20) to 
operate the spindle motor within the test container (such as 132). 
It will be clear that the present invention is well adapted to attain the 
ends and advantages mentioned as well as those inherent therein. While a 
presently preferred embodiment has been described for purposes of this 
disclosure, numerous changes may be made which will readily suggest 
themselves to those skilled in the art and which are encompassed in the 
spirit of the invention disclosed and as defined in the appended claims.