U.S. patent application number 15/804957 was filed with the patent office on 2018-03-01 for low resistance ground joints for dual stage actuation disk drive suspensions.
The applicant listed for this patent is Hutchinson Technology Incorporated. Invention is credited to Jeffry S. Bennin, Jacob D. Bjorstrom, Shawn P. Bopp, Reed T. Hentges, Michael T. Hofflander, Richard R. Jenneke, Craig A. Leabch, Mark S. Lewandowski, Zachary A. Pokornowski, Brian D. Schafer, Brian J. Stepien, John A. Theget, John E. Theisen, John L. Wagner.
Application Number | 20180061442 15/804957 |
Document ID | / |
Family ID | 51845813 |
Filed Date | 2018-03-01 |
United States Patent
Application |
20180061442 |
Kind Code |
A1 |
Bennin; Jeffry S. ; et
al. |
March 1, 2018 |
Low Resistance Ground Joints For Dual Stage Actuation Disk Drive
Suspensions
Abstract
A stainless steel dual stage actuated disk drive head suspension
baseplate including a plated electrical contact area having nickel
and gold. The baseplate can be heat treated. The nickel and gold
can be in a mixture.
Inventors: |
Bennin; Jeffry S.;
(Hutchinson, MN) ; Bjorstrom; Jacob D.;
(Hutchinson, MN) ; Bopp; Shawn P.; (Savage,
MN) ; Hentges; Reed T.; (Buffalo, MN) ;
Hofflander; Michael T.; (Edina, MN) ; Jenneke;
Richard R.; (Hutchinson, MN) ; Leabch; Craig A.;
(St. Cloud, MN) ; Lewandowski; Mark S.;
(Hutchinson, MN) ; Pokornowski; Zachary A.;
(Cokato, MN) ; Schafer; Brian D.; (Mound, MN)
; Stepien; Brian J.; (Glencoe, MN) ; Theget; John
A.; (Hutchinson, MN) ; Theisen; John E.;
(Winsted, MN) ; Wagner; John L.; (Plymouth,
MN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hutchinson Technology Incorporated |
Hutchinson |
MN |
US |
|
|
Family ID: |
51845813 |
Appl. No.: |
15/804957 |
Filed: |
November 6, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14974760 |
Dec 18, 2015 |
9812160 |
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15804957 |
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|
14531571 |
Nov 3, 2014 |
9245555 |
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14974760 |
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|
13114212 |
May 24, 2011 |
8885299 |
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14531571 |
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61396239 |
May 24, 2010 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G11B 5/4833 20130101;
G11B 5/4873 20130101; G11B 5/4853 20130101 |
International
Class: |
G11B 5/48 20060101
G11B005/48 |
Claims
1-16. (canceled)
17. A method for manufacturing a disk drive head suspension
baseplate, including: applying nickel and gold to a contact area of
a stainless steel baseplate; and heat treating the baseplate after
applying the nickel and gold.
18. The method of claim 17, including applying amounts of nickel
and gold to the stainless steel baseplate and heating the baseplate
to produce a contact area having about 2%-10% gold.
19. The method of claim 17 wherein applying nickel and gold
includes: applying a layer of material including nickel on the
stainless steel baseplate; and applying a layer of gold on the
layer of material including nickel.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 14/531,571, filed on Nov. 3, 2014, which is a
continuation of U.S. patent application Ser. No. 13/114,212, filed
May 24, 2011, now U.S. Pat. No. 8,885,299, issued Nov. 11, 2014,
which claims the benefit under 35 U.S.C. 119 of Provisional
Application No. 61/396,239, filed May 24, 2010, which are
incorporated herein by reference in their entirety for all
purposes.
TECHNICAL FIELD
[0002] The present invention relates to suspensions for disk
drives. In particular, the invention is a dual stage actuation
(DSA) suspension and method of manufacture.
BACKGROUND OF THE INVENTION
[0003] Dual stage actuation (DSA) disk drive head suspensions are
generally known and commercially available. By way of example, one
embodiment of a DSA head suspension 10 is shown in FIGS. 1A and 1B.
The illustrated DSA suspension includes a baseplate 12, hinge 14 or
spring region, load beam 16 and integrated lead flexure 18 with
traces 20. The hinge 14 is mounted to the baseplate 12 and extends
from the distal end of the baseplate. The load beam is mounted to
the distal end of the hinge 14. The flexure 18 is mounted to the
load beam 16, typically on the side of the load beam mounted to the
hinge 14. Welds such as 22 are typically used to join these
components. The baseplate 12, hinge 14 and load beam 16 are
typically formed from stainless steel, and the flexure 18 typically
includes a base layer of stainless steel. The copper or copper
alloy traces 20 on the flexure 18 are separated from the stainless
steel base layer by a layer of polyimide or other insulator.
[0004] The second stage actuation functionality of the illustrated
DSA suspension 10 is incorporated into the baseplate 12. As shown,
the baseplate 12 has one or more motor-receiving areas or openings
24 (two in the illustrated embodiment). Piezoelectric (PZT) motors
26 are mounted to the baseplate 12 in the motor-receiving openings
24. The motors 26 are mounted to tabs 28 extending from the
baseplate 12 into the motor-receiving openings 24. In the
illustrated suspension 10 the tabs 28 are portions of the hinge 14.
In other embodiments (not shown) the tabs 28 to which the PZT
motors 26 are mounted can be other components such as a separate
motor plate welded to the baseplate. Epoxy or other adhesive is
typically used to mount the motors 26 to the tabs 28.
[0005] DSA suspensions can be embodied in still other forms. For
example, an alternative DSA suspension structure is illustrated and
described in the Okawara U.S. Patent Publication No. 2010/0067151
which is incorporated herein by reference in its entirety and for
all purposes. Briefly, the suspension shown in the Okawara
publication has an actuator plate to which the motors are mounted.
The actuator plate is mounted between the baseplate and hinge. In
still other DSA suspensions (not shown), the motors can be mounted
to the load beam or hinge.
[0006] An electrical connection or conductive joint between an
electrical ground contact on a face of the motor and the ground
plane of the suspension is typically made by conductive adhesive
(e.g., epoxy with silver and/or nickel particles). The ground
contacts on the motors typically have an external plated gold (Au)
layer. These connections are typically formed by applying a mass of
the conductive adhesive at a location where the ground contact of
the motor is adjacent to a stainless steel portion of the
baseplate, load beam, hinge or flexure. The conductive adhesive
contacts both the motor ground contact and the stainless steel
portion of the suspension, thereby providing an electrical
connection or ground joint from the motor to the stainless steel
portions of the suspension that function as the ground plane.
[0007] The conductive joint between the motor and the ground plane
should be capable of functioning at or below a threshold level of
acceptable resistance under all applied processing and operational
load conditions. However, consistently maintaining acceptable
resistance to ground levels has been difficult. In particular, the
resistance of the conductive adhesive-to-stainless steel component
joints have been determined to be relatively high and unstable.
SUMMARY OF THE INVENTION
[0008] Embodiments of the invention include a stainless steel disk
drive head suspension baseplate including a plated contact area.
The plated contact area comprises nickel and gold. In embodiments,
the plated contact area comprises a mixture of nickel and gold. The
baseplate and contact area are heat treated in embodiments. The
baseplate is a dual stage actuated baseplate in embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 A is an isometric illustration of the flexure side of
a prior art dual stage actuation (DSA) suspension.
[0010] FIG. 1B is an isometric illustration of the opposite,
baseplate side of the prior art suspension shown in FIG. 1A.
[0011] FIG. 2 is a plan view illustration of a portion of a DSA
suspension in accordance with an embodiment of the invention having
a plated flexure.
[0012] FIG. 3 is a plan view illustration of an alternative
embodiment of the suspension shown in FIG. 2.
[0013] FIG. 4 is a side view illustration of a portion of a DSA
suspension in accordance with another embodiment of the invention
having a plated flexure.
[0014] FIG. 5 is a plan view illustration of the suspension shown
in FIG. 4.
[0015] FIG. 6 is a plan view illustration of a portion of a DSA
suspension in accordance with another embodiment of the invention
having a formed flexure tab.
[0016] FIG. 7 is a side view illustration of the suspension shown
in FIG. 6.
[0017] FIGS. 8 and 9 are plan view illustrations of portions of a
DSA suspension in accordance with another embodiment of the
invention having a plated hinge.
[0018] FIGS. 10 and 11 are plan view illustrations of portions of a
DSA suspension in accordance with another embodiment of the
invention having a plated hinge having a tab. The tab is shown
unformed in FIG. 10 and formed in FIG. 11.
[0019] FIG. 12 is an isometric illustration of the suspension shown
in FIG. 11.
[0020] FIGS. 13 and 14 are plan view illustrations of portions of a
DSA suspension in accordance with another embodiment of the
invention having a plated add-on feature.
[0021] FIG. 15 is a plan view illustration of a plated unformed
baseplate in accordance with another embodiment of the
invention.
[0022] FIG. 16 is a plan view illustration of the plated baseplate
in FIG. 15 in the formed state.
[0023] FIG. 17 is a plan view illustration of a portion of a DSA
suspension in accordance with an embodiment of the invention having
a plated plug.
[0024] FIG. 18 is a plan view illustration of the baseplate and
plated plug components of the suspension shown in FIG. 17.
[0025] FIG. 19 is a cross section side view illustration of the
assembled baseplate and plated plug components shown in FIGS. 17
and 18.
DETAILED DESCRIPTION
Overview
[0026] The invention is a dual stage actuation (DSA) suspension
having a stable, low resistance conductive adhesive electrical
connection or joint between an electrical contact on a motor of the
suspension and a plated metal contact area on a stainless steel
component of the suspension. One embodiment of the invention
includes a ground joint between the electrical contact of a
piezoelectric (PZT) motor and a gold or nickel gold plated contact
area on the stainless steel suspension component. The gold or
nickel gold or other conductive and generally non-corrosive metal
or alloy plated area on the stainless steel suspension component is
referred to generally in the description of the invention below as
the plated region. In still other embodiments a layer of nickel is
plated on the stainless steel, and a gold layer is plated on the
nickel layer.
[0027] As described below in connection with the attached drawing
figures, the invention can be embodied in a number of different
structures. For example, the invention can be embodied in DSA
suspensions such as that described above in connection with FIGS.
1A and 1B. Alternatively, the invention can be embodied in DSA
suspension structures of the type disclosed in the Okawara U.S.
Patent Publication No. 2010/0067151. For example, the stainless
steel suspension component to which the ground joint is made can be
a baseplate, load beam, hinge, motor plate, flexure or other
component. The plated contact area on the stainless steel
suspension component can be heat treat annealed. In some
embodiments of the invention, the plated contact surface retains a
full surface coverage of the plated alloy. In other embodiments of
the invention the plated contact surface includes approximately 98%
stainless steel and 2% gold following the heat treat and annealing
process. In yet other embodiments, the plated contact surface
includes about 90% stainless steel surface and about 10% gold. Only
the portion of the component to which the conductive adhesive
ground joint is being made need be plated (e.g., patterned and
selectively plated), although in other embodiments larger areas or
even the entire component surface can be plated.
[0028] The invention provides a reliable, stable and low resistance
joint between the conductive adhesive and the plated stainless
steel contact area. The desired resistance level can vary with the
application of the suspension (e.g., with the drive circuitry that
the motor is to be connected). One example specification calls for
ground contact resistance levels no greater than 2500 ohms. Another
specification calls for resistance levels no greater than 100 ohms.
Still other embodiments of the invention have a resistance no
greater than 10 ohms and even less than 1 ohm over the life of the
suspension.
Plated Flexure Embodiments
[0029] FIG. 2 illustrates portions of a suspension 110 in
accordance with an embodiment of the invention having a through
hole or opening 130 in the baseplate 112 that exposes a gold plated
contact 132 on the flexure 118. Features of the suspension 110 that
are similar to those of suspension 10 described above in connection
with FIGS. 1A and 1B are identified by similar reference numbers in
the "100" series. Conductive adhesive 134 extends from the motor
contact 136, over the baseplate 112, into and through the baseplate
opening 130, and to the plated flexure contact 132. The plated
contact 132 on the flexure 118 can be a contact plated directly
onto the stainless steel base layer of the flexure 118. In an
alternative embodiment shown in FIG. 3 illustrating portions of
suspension 110' a through hole 131' is etched or otherwise formed
through the stainless steel base layer of the flexure 118' to
expose a plated portion of a trace 120' on the flexure. In this
alternative embodiment the conductive adhesive 134' extend through
the holes 130' and 131' in the baseplate 112' and the flexure 118',
and contacts the plated flexure trace 120'.
[0030] FIGS. 4 and 5 illustrate portions of a suspension 210 in
accordance with another embodiment of the invention. Features of
the suspension 210 that are similar to those of suspension 10
described above in connection with FIGS. 1A and 1B are identified
by similar reference numbers in the "200" series. In this
embodiment the mass of conductive adhesive 234 extends from the
motor contact 236, over the edge of the motor 226, into a gap 227
between the motor and baseplate 212, and into contact with the
plated contact region 232 on the flexure 218. As with the
embodiment shown in FIGS. 2 and 3, the plated contact 232 on the
flexure 218 can be on the stainless steel base layer or on a trace
exposed at a through hole (not shown) in the flexure.
Non-conductive adhesive 233 is used to mount the motor 226 to the
hinge tabs 228 and isolate the second (bottom) electrode of the
motor from the conductive adhesive 234 of the ground joint.
Formed Flexure Embodiments
[0031] FIGS. 6 and 7 illustrate portions of a suspension 310 in
accordance with another embodiment of the invention having a
flexure 318 with a tab 360 or paddle on the stainless steel base
layer 361 that has a plated contact 362. Features of the suspension
310 that are similar to those of suspension 10 described above in
connection with FIGS. 1A and 1B are identified by similar reference
numbers in the "300" series. The flexure tab 360 is formed (e.g.,
two 90.degree. bends 363, 364 are shown) to extend out of the plane
of the other portions of the flexure 318, through a gap 365 between
the baseplate 312 and motor 324, and into contact with the ground
contact 336 on the motor. A mass of conductive adhesive 334 joins
the plated contact 362 on the formed flexure tab 360 to the motor
ground contact 336.
Plated Hinge Embodiments
[0032] FIGS. 8 and 9 illustrate portions of a suspension 410 in
accordance with another embodiment of the invention having a plated
contact 470 on a portion of the hinge near or adjacent to the motor
426 (e.g., the hinge motor tab). FIG. 9 shows the suspension 410
after a de-tabbing step relative to FIG. 8. Features of the
suspension 410 that are similar to those of suspension 10 described
above in connection with FIGS. 1A and 1B are identified by similar
reference numbers in the "400" series. The conductive adhesive 434
extends from the motor contact 436 over the edge of the motor 426
and into contact with the plated contact 470 on the hinge 414. In
the illustrated embodiments the conductive adhesive 434 also
extends over a portion of the baseplate 412 and the edge of the
baseplate.
[0033] FIGS. 10-12 illustrate portions of suspension 510 in
accordance with another embodiment of the invention having a formed
plated hinge 514. Features of the suspension 510 that are similar
to those of suspension 10 described above in connection with FIGS.
1A and 1B are identified by similar reference numbers in the "500"
series. A plated contact 570 is formed on a tab 580 extending from
the hinge 514. The tab 580 is shown in an unformed state in FIG.
10. During suspension 510 assembly the tab 580 is formed to extend
up the edge and over the baseplate 512 at a location adjacent to
the motor 526. The conductive adhesive 534 extends between the
motor ground contact 536 and the plated contact 570 on the formed
tab 580, across the baseplate 512.
Add-On Feature Embodiments
[0034] FIGS. 13 and 14 illustrate portions of a suspension 610 in
accordance with another embodiment of the invention including a
separately manufactured plated element or feature 682 that is
welded (e.g., by welds 622) or otherwise attached to the baseplate
612 adjacent to the motors 626. The conductive adhesive 634 extends
from the motor contact pad 636 to the plated surface 681 of the
feature 682, over the edge of the feature. FIG. 14 shows the
suspension 610 after a de-tabbing step and application of
conductive adhesive 634 relative to FIG. 13.
Plated Baseplate Embodiments
[0035] FIGS. 15 and 16 illustrate plated baseplates 712 in
accordance with another embodiment of the invention. A plated
stripe 790 is formed on the baseplate stock. FIG. 15 shows the
baseplate 712 unformed. The stock is formed with the plated stripe
790 located adjacent to the motor openings 724 as shown in FIG. 16.
The mass of conductive adhesive (not shown) will extend between the
motor contact (not shown) and the plated portion 790 of the
baseplate 712.
Plated Plug Baseplate
[0036] FIGS. 17-19 illustrate portions of a suspension 810 in
accordance with another embodiment of the invention including
plated stainless steel plugs 892 in the baseplate 812. Features of
the suspension 810 that are similar to those of suspension 10
described above in connection with FIGS. 1A and 1B are identified
by similar reference numbers in the "800" series. The plated plugs
892 can be manufactured separately from the baseplate 812, and
mechanically forced into holes in the baseplate with the plated
surface 893 oriented toward the same side of the baseplate as the
motor contacts 836. The plug 892 can be press fit, coined or
otherwise forced into the hole in the baseplate 812 to form a
substantial and secure mechanical, and low resistance contact
between the plug and baseplate. Coining provides the additional
adavantage of leaving a depression that can be useful in adhesive
wicking control. FIG. 19 is a cross section view of an assembled
baseplate 812 and plated plug 892. The conductive adhesive 834 is
applied so that it extends between the plated surface 893 of the
plug 892 and the motor ground contact 836.
[0037] Although the invention is described with reference to a
number of different embodiments, those skilled in the art will
recognize that changes can be made in form and detail without
departing from the spirit and scope of the invention.
* * * * *