U.S. patent application number 11/858652 was filed with the patent office on 2009-03-26 for systems and methods for electroplating embossed features on substrates.
Invention is credited to Karl S. Weibezahn.
Application Number | 20090078579 11/858652 |
Document ID | / |
Family ID | 40470489 |
Filed Date | 2009-03-26 |
United States Patent
Application |
20090078579 |
Kind Code |
A1 |
Weibezahn; Karl S. |
March 26, 2009 |
Systems And Methods For Electroplating Embossed Features On
Substrates
Abstract
Systems and methods for electroplating embossed features on
substrates are disclosed. In an exemplary implementation, a method
may include positioning a device in close proximity to an anode.
The device may have embossed trenches. The method may also include
delivering pressurized electrolyte to the anode. The method may
also include activating electrical power between the anode and the
device. The metal ions migrate into the embossed trenches to form
electroplated metal traces on the device
Inventors: |
Weibezahn; Karl S.;
(Corvallis, OR) |
Correspondence
Address: |
HEWLETT PACKARD COMPANY
P O BOX 272400, 3404 E. HARMONY ROAD, INTELLECTUAL PROPERTY ADMINISTRATION
FORT COLLINS
CO
80527-2400
US
|
Family ID: |
40470489 |
Appl. No.: |
11/858652 |
Filed: |
September 20, 2007 |
Current U.S.
Class: |
205/133 ;
204/215; 204/284 |
Current CPC
Class: |
C25D 5/08 20130101; C25D
7/00 20130101; C25D 17/10 20130101; C25D 17/12 20130101 |
Class at
Publication: |
205/133 ;
204/215; 204/284 |
International
Class: |
C25D 5/02 20060101
C25D005/02 |
Claims
1. A method for electroplating embossed features on a substrate,
comprising: positioning a device in close proximity to an anode,
the device having embossed trenches; delivering pressurized
electrolyte to the anode; and activating electrical power between
the anode and the device, wherein metal ions migrate into the
embossed trenches to form electroplated metal traces on the
device.
2. The method of claim 1, further comprising fully wetting the
anode before activating electrical power.
3. The method of claim 1, further comprising applying pressure to
the device to reduce space between the device and the anode.
4. The method of claim 1, further comprising returning electrolyte
to a reservoir.
5. The method of claim 1, further comprising preventing
short-circuiting even if the electroplated metal traces
inadvertently contact the anode.
6. The method of claim 1, further comprising forcing air between
the anode and the electrolyte through pores formed in the
anode.
7. The method of claim 1, further comprising supplying the metal
ions from the electrolyte.
8. The method of claim 1, further comprising supplying the metal
ions from the anode.
9. A system for electroplating embossed features on a substrate,
comprising: an anode configured to be positioned in close proximity
to a device; a pump operating to deliver a pressurized electrolyte
to the anode; and electrical power for connecting between the anode
and the device, the electrical power causing metal ions to migrate
onto exposed metal surfaces on the device to form electroplated
metal traces.
10. The system of claim 9, further comprising a planar production
configuration.
11. The system of claim 9, further comprising a roll-to-roll
production configuration.
12. The system of claim 9, wherein the device serves as a cathode
for an electroplating circuit.
13. The system of claim 9, wherein the anode is fully wetted before
activating electrical power.
14. The system of claim 9, wherein the anode is hydrophilic.
15. The system of claim 9, wherein an outer layer of the anode is
non-conductive ceramic to prevent short-circuiting even if the
electroplated metal traces inadvertently contact the anode.
16. The system of claim 9, wherein the anode is non-sacrificial and
metal ions are provided at least in part from the electrolyte.
17. The system of claim 9, wherein the anode is sacrificial and
metal ions are provided at least in part from the anode.
18. The system of claim 9, further comprising embossed trenches on
the device, the embossed trenches corresponding to desired traces
on the device to the electrolyte.
19. A system for electroplating embossed features on a substrate,
comprising: fluid delivery means for providing a metered flow of
pressurized electrolyte to a device having embossed trenches;
positive charge means for delivering metal ions into the embossed
trenches of the device; and negative charge means for attracting
the metal ions into the embossed trenches, wherein the metal ions
migrate uniformly into the embossed trenches to form electroplated
metal traces on the device.
20. The method of claim 1, further comprising secondary means for
providing metal ions.
21. A system for electroplating embossed features on a substrate,
comprising: a drum anode rotatably positioned directly adjacent to
a device having resin-embossed features, the device in constant
contact with substantially a same position on the drum anode while
the drum rotates; a pump operating to deliver a continuous
pressurized electrolyte inside the drum anode; pores formed in the
drum anode to expel electrolyte onto the device as the device
rotates over an external surface of the drum, and electrical power
for connecting between the drum anode and the device, the
electrical power causing metal ions to migrate through the pores
onto exposed metal surfaces formed by the resin-embossed features
on the device to form electroplated metal traces.
Description
BACKGROUND
[0001] Electroplating is a well-known technique for covering
surfaces of a substrate with a metal. In general, electroplating
systems include a tank for holding a chemical solution or "plating
bath" which contains the metal to be plated, an anode (positive
charge), and a cathode (negative charge). A substrate to be
electroplated is placed in the plating bath and a charge is
applied, causing the metal to come out of solution and deposit on
the substrate.
[0002] Electroplating techniques arc used for a wide variety of
applications, such as, in computers, mobile phones, and other
electronic devices, to name only a few examples. Advanced
techniques may be used to fabricate more elaborate devices. For
example, to fabricate electrical circuits that drive a pixilated
flexible display (or other flex circuits), a conductive substrate
is first coated with a resin, patterned with traces by
pressure-embossing, and then cured. The substrate is then placed
into the plating bath so that the resin removed by the embossing is
replaced with electroplated nickel (or other metal).
[0003] It is often difficult, however, to maintain a uniform
plating thickness along the traces on the substrate during the
electroplating process because of radical asymmetry and/or
variation in trace density inherent in more complicated circuit
designs. Plating "shields" are physical, non-conductive
obstructions that may be placed between the anode and cathode in
the plating tank to affect more uniform plating thickness through
current density redirection. Although reasonably effective, shields
must be modeled, designed, and fabricated specifically for each
substrate that is to be electroplated. Segmented anodes also may be
used to help bias the current flow away from edges and toward areas
of greater trace concentration, but with a similarly marginal
effect. In general, these techniques rely on trial and error and
are application specific.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] FIGS. 1a-b show a side, cross-sectional view of an exemplary
planar electroplating system which may be implemented for
electroplating embossed features on a substrate, wherein (a) shows
a partially-plated metal trace, and (b) shows a completely-plated
metal trace.
[0005] FIG. 2 shows a side, cross-sectional view of an exemplary
roll-to-roll electroplating system which may be implemented for
electroplating embossed features on a substrate.
[0006] FIG. 3 is a flowchart illustrating exemplary operations
which may be implemented for electroplating embossed features on a
substrate.
DETAILED DESCRIPTION
[0007] Exemplary systems and methods described herein for
electroplating embossed features on a substrate may be used to
improve: plating thickness uniformity and enables greater
flexibility in device design. The electroplating systems and
methods use a conductive web substrate as the cathode, and replace
the part-specific anode and shield combinations of conventional
electroplating systems with a single, close-proximity anode that
serves as both a current source and an electrolyte supply vessel.
The anode "smooths out" both the current density and the metal ion
flow to the device, and thus results in a more uniform metal
buildup during the deposition process. The close-coupled anode
configuration also enables the large volume, open plating bath to
be reduced in size or even eliminated altogether. The conductive
web substrate results in traces only where the web is exposed to
the electrolyte (the bottom of the trenches), and nowhere else.
Exemplary System
[0008] FIGS. 1a-b show a side, cross-sectional view of an exemplary
planar electroplating system 100 which may be implemented for
electroplating embossed features on a substrate 110. FIG. 1a shows
a partially-plated metal trace 112 on the substrate 110 (e.g.,
during the electroplating procedure). FIG. 1b shows a
completely-plated metal trace 114 on the substrate 110 (e.g.,
following the electroplating procedure).
[0009] In an exemplary embodiment, the substrate 110 may be
prepared in advance for the electroplating procedure by coating the
substrate with a dielectric resin 115 that protects the surface of
the substrate 110 from being plated during the electroplating
procedure. The resin may then be pressure-embossed to remove a
portion of the resin and create "trenches" 117a-b exposing
conductive portions 118a-b of the substrate 110 corresponding to
the desired traces that are to be electroplated. After curing, the
substrate is ready for the electroplating process, e.g., using
system 100.
[0010] Exemplary system 100 may comprise a plating fixture 120. The
plating fixture 120 may be manufactured of a non-conductive
material (e.g., plastic), and holds a small fluid plenum 122 of
heated electrolyte 124. The electrolyte 124 may be provided to the
plating fixture 120 by an electrolyte supply system 130. The supply
system 130 may include an electrolyte reservoir 131, a pump 132, a
valve 133, a heater 134, and a filter 135. During operation, the
supply system 130 provides a metered, pressurized supply of warm,
particle-free electrolyte to the plating fixture 120.
[0011] It is noted that the components shown in FIG. 1a are
intended only to illustrate one example of a system 100 which may
be implemented. Other embodiments are also contemplated and may
include additional components, components comprised of multiple
parts, and/or fewer components. The system 100 is not limited to
those components shown.
[0012] The plating fixture 120 is designed to support an anode
device 140. In an exemplary embodiment, the anode device 140 is a
composite anode. As better shown in the cut-away 145 in FIG. 1a,
the anode 140 may comprise a thick metal-doped porous ceramic layer
141, sandwiched between two similar but thinner, non-conductive
layers 142a-b.
[0013] The conductive porous ceramic material 141 has been used for
some time in fuel cells, for the creation of hydrogen peroxide, and
in metals production. Low flow-resistance to liquid, however, is a
less-common attribute and requires a particularly suited material.
By way of example, such a material is described, e.g., in U.S. Pat.
No. 4,892,857 titled "Electrically Conductive Ceramic Substrate" of
Tennent, et al. and assigned to Corning Incorporated (Corning,
N.Y.). These and other materials now known or later developed may
be used to implement the described systems and methods.
[0014] It is noted that the anode 140 may be a "sacrificial" anode,
wherein the anode itself provides at least some of the metal ions
for the electroplating process and is disposed of when there are
insufficient metal ions remaining in the anode for the
electroplating process. Alternatively, the anode 140 may be a
"non-sacrificial" anode, wherein the metal ions are provided
primarily by the heated electrolyte 124. In any event, use of a
porous conductive ceramic as the anode enables the substrate 110
that is to be plated to be positioned against (or very close to)
the anode 140 during the electroplating process.
[0015] The system 100 may also comprise an electric power supply
150. In an exemplary embodiment, the electric power supply 150 may
be a regulated DC power supply selected to provide the electrical
current necessary for the electroplating process. In any event, the
electric power supply 150 electrically connects the anode 140 to
the substrate 110 (which serves as the cathode in the
electroplating circuit).
[0016] During operation, a device (e.g., the resin-coated and
embossed substrate described above) is placed over the anode 140 in
the plating fixture 120. The pump 132 is activated, providing a
metered flow of heated electrolyte 124 to the small plenum 122
under the anode 140 in the plating fixture 120. As the fluid level
rises within the plating fixture 120, air is forced out through the
porous anode 140. The electrolyte 124 reaches the anode 140, and by
virtue of its being hydrophilic, the anode 140 becomes fully
wetted. The electrolyte 124 then wets the surface of the device.
Flowing electrolyte 124 may be collected and returned to the main
supply reservoir 131.
[0017] In some embodiments, a slight uniform pressure may be
applied to the device to limit the fluid-filled gap between the
device and anode 140 so that it is only a very thin film. The power
supply 150 is then activated and the metal ions from the
electrolyte 124 (e.g., when using a non-sacrificial anode 140)
and/or from the doped internal layer of the anode (e.g., when using
a sacrificial anode 140) migrate to the exposed surfaces 118a-b of
the substrate 110 (e.g., in trenches 117a-b as illustrated by
arrows 160). If the plating inadvertently makes contact with the
anode 140, the anode's outer layer 142a-b of non-conductive ceramic
prevents short-circuiting of the electroplating circuit.
[0018] The exposed conductive surfaces 117a-b on the device
correspond to the embossed trenches 118a-b (e.g., the desired
traces). Accordingly, the metal ions accumulate as electroformed
features only in these trenches 118a-b. When the desired plating
thickness is achieved (e.g., when the metal has accumulated so that
it is flush with the surrounding resin as shown in FIG. 1b), the
electrical power 150 may be disconnected (as indicated by the "X"
in FIG. 1b) and the device removed for rinsing and drying.
[0019] The system 100 enables improved plating thickness
uniformity. Proper electrical performance of the device depends on
predictable trace resistance, which can only be achieved through
predictable trace thickness. Embodiments described herein reduce or
altogether eliminate the uncertainty inherent in conventional
processes. The system 100 is also universally applicable.
Predictable trace thickness may be achieved without regard to
device design. The system 100 also reduces the size and complexity
of the electroplating system. There is no need for a large open
tank (less real estate, less environmental impact), no need for a
large volume of plating solution (lower cost), and fewer
accessories are needed (no shields or mixer is required). The
system 100 also enables better temperature control. The temperature
uniformity of the much-reduced, essentially enclosed volume of
electrolyte is easier to maintain at a constant level.
[0020] It is noted that the system 100 described above is shown for
purposes of illustration only, and is not intended to be limiting.
Other embodiments are also contemplated. For example, the
electroplating system described above may also be effectively
adapted to a high-throughput manufacturing environment, as
described below with reference to FIG. 2.
[0021] Previous roll-to-roll electroplating systems included a
series of tanks through which the substrate is drawn. The anodes
and shields within these tanks had to be sized and located somewhat
generically to roughly achieve their intended purposes. However,
the anodes and shields could not move with the substrate and
therefore could not effectively accommodate the subtleties of
multiple device designs.
[0022] FIG. 2 shows a side, cross-sectional view of an exemplary
roll-to-roll electroplating system 200 which may be implemented for
electroplating embossed features on a substrate 210 in a
high-throughput environment. It is noted that 200-series reference
numbers are used to refer to similar components already described
above with reference to FIGS. 1a-b, and therefore may not be
described again with reference to FIG. 2.
[0023] In the exemplary embodiment of system 200 shown in FIG. 2,
the anode 240 may be configured as a rotating electrolyte-filled
"drum" or cylinder 270 to enable continuous roll-to-roll plating. A
supply system 230 may be implemented to deliver electrolyte 224
into the drum 270 via piping 280. In one embodiment, system 200
includes an electrolyte recovery system 285 to recycle the
electrolyte.
[0024] During operation, the supply system 230 pressurizes the
electrolyte 224 in drum 270, pushing the electrolyte 224 out from
inside the drum 270 and into close proximity of the substrate 210.
The process is continuous as the substrate is wrapped around at
least a portion of drum 270. That is, the new substrate 210 with
exposed metal portions 217 enters on one side of the drum (as shown
in inset 290), contacts the drum 270 during the electroplating
process, and is removed after the electrolyte has been deposited on
exposed metal portions 217 (as shown in inset 291). It is noted
that there is no relative motion between the anode and the device
during the electroplating process, e.g., as indicated by contact
points 275a-g.
Exemplary Operations
[0025] FIG. 3 is a flowchart illustrating exemplary operations
which may be implemented for electroplating embossed features on a
substrate. Operations 300 may be implemented by the system
described above, e.g., by an electronic controller executing logic
instructions on one or more computer-readable medium. When executed
by the controller, the logic instructions may program the system as
a special-purpose machine that implements the described operations.
However, the operations are not limited to automatic
implementation, and may also be implemented manually, or in a
combination of manual and automatic process steps. In an exemplary
implementation, the components and connections depicted in the
figures may be used.
[0026] In operation 310, a device having embossed trenches may be
positioned over an anode. For example, the device may be positioned
in a planar production configuration (e.g., as shown in FIGS.
1a-b). Or for example, the device may be positioned in a
roll-to-roll production configuration (e.g., as shown in FIG.
2).
[0027] In operation 320, a metered flow of heated electrolyte may
be delivered under the anode. As the level of the heated
electrolyte rises within the fixture, air is forced out through the
porous anode. The heated electrolyte eventually reaches the anode,
which becomes fully wetted. The heated electrolyte then wets the
surface of the device. In some embodiments, excess heated
electrolyte may be collected and returned to the main supply
reservoir. Also in some embodiments, a slight uniform pressure may
be applied to the device to limit the fluid-filled gap between the
device and the anode.
[0028] In operation 330, electrical power may be activated between
the anode and the device. When power is applied in operation 330,
metal ions migrate into the embossed trenches to form electroplated
metal traces on the device. In an exemplary embodiment, metal ions
may migrate from the electrolyte (e.g., where a non-sacrificial
anode is used). In another exemplary embodiment, metal ions may
migrate from a doped internal layer of the anode (where a
sacrificial anode is used). In yet another exemplary embodiment,
metal ions may migrate from both the electrolyte and a doped
internal layer of the anode.
[0029] Once the desired plating thickness has been reached (e.g.,
when the metal traces are flush with the surrounding resin), the
power may be disconnected, and the device may be removed for
rinsing and drying.
[0030] The operations shown and described herein are provided to
illustrate exemplary implementations for electroplating embossed
features on a substrate. It is noted that the operations are not
limited to the ordering shown. Still other operations may also be
implemented.
[0031] It is noted that the exemplary embodiments shown and
described are provided for purposes of illustration and are not
intended to be limiting. Still other embodiments are also
contemplated for electroplating embossed features on a
substrate.
* * * * *