U.S. patent application number 13/737719 was filed with the patent office on 2013-06-06 for apparatus for forming films on substrates.
This patent application is currently assigned to INTERMOLECULAR, INC.. The applicant listed for this patent is INTERMOLECULAR, INC.. Invention is credited to Stephen Mark Lambert, Peter Wing Leung, Dennis Mullins, Cuong Manh Ta.
Application Number | 20130142955 13/737719 |
Document ID | / |
Family ID | 39943795 |
Filed Date | 2013-06-06 |
United States Patent
Application |
20130142955 |
Kind Code |
A1 |
Lambert; Stephen Mark ; et
al. |
June 6, 2013 |
APPARATUS FOR FORMING FILMS ON SUBSTRATES
Abstract
A doctor blade assembly for use in combination with apparatus
for forming a film on a substrate. The doctor blade assembly
includes a doctor blade to be mounted on a programmable robot. The
doctor blade has a bottom face and spacers at opposite ends of the
body of the doctor blade extending a predetermined distance down
below the bottom face of the body for contacting a substrate and
spacing the bottom face from the substrate. The spacers are
adjustable relative to the doctor blade for adjusting the
predetermined distance according to the thickness of film to be
formed on the substrate. Other aspects and methods are also
disclosed.
Inventors: |
Lambert; Stephen Mark;
(Castro Valley, CA) ; Mullins; Dennis; (Sunnyvale,
CA) ; Ta; Cuong Manh; (San Jose, CA) ; Leung;
Peter Wing; (Fremont, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
INTERMOLECULAR, INC.; |
San Jose |
CA |
US |
|
|
Assignee: |
INTERMOLECULAR, INC.
San Jose
CA
|
Family ID: |
39943795 |
Appl. No.: |
13/737719 |
Filed: |
January 9, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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12599061 |
Nov 6, 2009 |
8375888 |
|
|
PCT/US2007/068375 |
May 7, 2007 |
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13737719 |
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Current U.S.
Class: |
427/356 ;
118/100; 29/402.01 |
Current CPC
Class: |
B05C 11/028 20130101;
B23P 6/00 20130101; B05C 9/12 20130101; B05D 3/12 20130101; Y10T
29/49718 20150115 |
Class at
Publication: |
427/356 ;
118/100; 29/402.01 |
International
Class: |
B05C 9/12 20060101
B05C009/12; B23P 6/00 20060101 B23P006/00; B05D 3/12 20060101
B05D003/12 |
Claims
1. Apparatus for forming films on substrates, comprising: a doctor
blade, a programmable robot for moving the doctor blade along X, Y
and Z axes, the X and Y-axes being generally horizontal and the Z
axis being generally vertical, and a flexible coupling for coupling
the doctor blade to the robot, said flexible coupling being
configured for exerting a downward force on the doctor blade as it
moves along a substrate during the formation of a film on the
substrate.
2. Apparatus as set forth in claim 1 wherein said downward force is
a spring force having a vertical component and a horizontal
component.
3. Apparatus as set forth in claim 2 wherein said flexible coupling
comprises a spring member having a longitudinal axis.
4. Apparatus as set forth in claim 3 wherein said spring member is
adapted to bend along its longitudinal axis as it exerts said
downward force on the doctor blade.
5. Apparatus as set forth in claim 3 wherein said spring member has
a releasable connection with said doctor blade.
6. Apparatus as set forth in claim 3 wherein said doctor blade
comprises a body having a bottom face adapted to be spaced a
predetermined distance from the substrate to form a gap between the
bottom surface and the substrate generally corresponding to the
thickness of the film to be formed on the substrate, and wherein
said bottom face lies in a plane oblique to the longitudinal axis
of the spring member when the spring member is in a relaxed
condition.
7. Apparatus as set forth in claim 3 wherein said flexible coupling
comprises a first pin having a lower end connected to the spring
member and an upper end adapted for connection to said robot, and a
second pin having a lower end connected to the doctor blade and an
upper end spaced from the lower end of the first pin.
8. Apparatus as set forth in claim 7 wherein the first and second
pins have first and second longitudinal axes, respectively, said
axes being generally co-axial with one another when the spring
member is in a relaxed condition and skewed relative to one another
when the spring member exerts a downward force on the doctor blade
during a film-forming operation.
9. A method of adjusting the gap of a doctor blade to vary a
thickness of film formed by the doctor blade, said method
comprising: providing a doctor blade having a body and opposite
ends; and adjusting spacers at opposite ends of the body to extend
a selected distance below the body of the doctor blade, said
distance being adjustable according to the thickness of the film to
be formed.
10. A method as set forth in claim 9 further comprising mounting
said doctor blade on a programmable robot after the spacers have
been adjusted.
11. A method as set forth in claim 9 wherein said robot is movable
along X, Y and Z-axes.
12. A method of forming a film on a substrate, comprising moving
the doctor blade across a substrate to form a film on the
substrate; and while moving the doctor blade across the substrate,
applying a downward force to the doctor blade having both
horizontal and vertical force components.
13. A method as set forth in claim 12 further comprising mounting a
doctor blade on a programmable robot for movement across the
substrate.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This is a Divisional Application of U.S. patent application
Ser. No. 12/599,061, filed on Nov. 6, 2009, which claims priority
to PCT Application No. PCT/US07/68375, filed on May 7, 2007, each
of which are herein incorporated by reference for all purposes.
FIELD OF THE INVENTION
[0002] This invention relates to apparatus and methods for handling
substrates, and more particularly to such apparatus and methods
which involves the use of a programmable robot and related
accessories to automate a workflow, such as a process for forming
films on substrates.
BACKGROUND
[0003] Automation is well established in the field of materials
discovery and research. Over the past several years, there have
been efforts to apply automation and high throughput techniques
into various development labs in which automated systems have been
set up to serve dedicated workflows. For example, there are a
number of automated reactor systems that have been used for
synthesis screening and process optimization. See, for example, J.
Am. Chem. Soc. 2003, 125, 4306-4317; "An Automated Approach to
Process Optimization, Parameter Setting, and Robustness Testing"
Organic Process R&D 2001, 5, 331-334; J. Am. Chem. Soc. 2002,
124, 15280 15285; "Automated Workstations for Parallel Synthesis"
Organic Process R&D 2002, 6, 833-840; "Parallel solid-phase
synthesis, screening, and encoding strategies for
olefin-polymerization catalysts." Tetrahedron 1999, 55(39),
11699-11710; "An integrated high-throughput workflow for
pre-formulations: Polymorphs and salt selection studies"
Pharmachem, 2003, 1(7/8); and "Application of high throughput
technologies to drug substance and drug product development"
Computers and Chem. Eng. 2004, 28, 943-953.
[0004] The above efforts include procedures intended to automate
the formation of a library of liquid samples and films formed from
such samples by using certain contact and non-contact methods to
apply a spreading force to the samples. See, e.g., published U.S.
patent application Ser. No. 10/448,788, published Apr. 15, 2004
(Publication No. 2004/0071888); and published U.S. patent
application Ser. No. 9/682,829, published Apr. 24, 2003
(Publication No. 2003/0677390).
[0005] While these examples highlight that automation has been
successfully applied to dedicated workflows, there is a need for
even more flexible and efficient automation systems.
SUMMARY
[0006] In one aspect, this invention is directed to apparatus for
forming films on substrates. The apparatus comprises a doctor blade
assembly and a programmable robot for moving the assembly along X,
Y and Z-axes, the X and Y-axes being generally horizontal and the
Z-axis being generally vertical. The doctor blade assembly
comprises a doctor blade adapted to be mounted on the robot. The
doctor blade comprises a body having a bottom face and spacers at
opposite ends of the body of the doctor blade extending a
predetermined distance down below the bottom face of the body for
contacting a substrate and spacing the bottom face from the
substrate. The spacers are adjustable relative to the body of the
doctor blade for adjusting the predetermined distance according to
the thickness of film to be formed on the substrate.
[0007] In another aspect, this invention is directed to a doctor
blade assembly as described in the preceding paragraph independent
of a programmable robot.
[0008] In another aspect, this invention is directed to apparatus
comprising a doctor blade, and a programmable robot for moving the
doctor blade along X, Y and Z axes. The apparatus also includes a
flexible coupling for coupling the doctor blade to the robot. The
flexible coupling is configured for exerting a downward force on
the doctor blade as it moves along a substrate during the formation
of a film on the substrate.
[0009] In another aspect, this invention is directed to a method of
adjusting the gap of a doctor blade to vary a thickness of film
formed by the doctor blade. The method comprises providing a doctor
blade having a body and opposite ends, and adjusting spacers at
opposite ends of the body to extend a selected distance below the
body of the doctor blade. The selected distance is adjustable
according to the thickness of the film to be formed.
[0010] In yet another aspect, this invention is directed to a
method of forming a film on a substrate. The method comprises
moving the doctor blade across a substrate to form a film on the
substrate, and while moving the doctor blade across the substrate
applying a downward force to the doctor blade having both
horizontal and vertical force components.
[0011] The details of embodiments of the invention are set forth in
the accompanying claims, drawings and description, below. Other
features, objects, and benefits of the invention will be apparent
from the description and drawings.
DESCRIPTION OF DRAWINGS
[0012] FIG. 1 is a perspective of an automated workstation
incorporating apparatus of the present invention;
[0013] FIG. 2 is an enlarged portion of FIG. 1 showing, among other
things, pick-up and vacuum stations of the workstation;
[0014] FIG. 3 is a perspective of a gripping mechanism used for
gripping a substrate holder of the present invention;
[0015] FIG. 4 is a perspective of the vacuum station;
[0016] FIG. 5 is an enlarged vertical section taken in the plane of
line 5-5 of FIG. 4;
[0017] FIG. 6 is a perspective of a substrate holder;
[0018] FIGS. 7-9 are sectional views illustrating a sequence of
steps during which a substrate in a substrate holder is deposited
on a vacuum device at the vacuum station;
[0019] FIG. 10 is a perspective showing a number of substrate
holders stacked one on top of another;
[0020] FIG. 11 is a perspective of a portion of a robot carrying a
suction assembly and a doctor blade assembly of this invention;
[0021] FIG. 12 is a view similar to FIG. 11 but rotated about a
vertical axis to show additional details;
[0022] FIG. 13 is an enlarged perspective showing components of the
doctor blade assembly;
[0023] FIG. 14 is an enlarged vertical section taken in the plane
of line 14-14 of FIG. 13;
[0024] FIG. 15 is a perspective view of a flexible coupling, a
doctor blade, and adjustable feet on the doctor blade, parts being
exploded to show various features;
[0025] FIG. 16 is a perspective view of the flexible coupling
assembled with doctor blade;
[0026] FIG. 17 is a vertical section taken in the plane of line
17-17 of FIG. 16 showing the feet of the doctor blade spaced above
a substrate and the flexible coupling in a relaxed condition;
[0027] FIG. 18 is a view similar to FIG. 17 but showing the feet of
the doctor blade in contact with the substrate for forming a film,
and the flexible coupling bent to exert a downward and rearward
force on the doctor blade;
[0028] FIG. 19 is a vertical section showing the doctor blade
moving across a substrate to form a film thereon;
[0029] FIG. 20 is a perspective of a tool for adjusting the feet on
the doctor blade to provide a film of desired thickness;
[0030] FIG. 21 is a vertical section taken in the plane of line
21-21 of FIG. 20;
[0031] FIG. 22 is an enlarged portion of FIG. 21 showing the doctor
blade and flexible coupling positioned in the tool; and
[0032] FIG. 23 is a view similar to FIG. 22 showing the tool
forcing the doctor blade to the left against a gage for setting the
desired film-forming gap between the doctor blade and a reference
surface.
[0033] Corresponding parts are designated by corresponding
reference numbers throughout the drawings.
DETAILED DESCRIPTION
[0034] FIGS. 1 and 2 illustrate an automated workstation, generally
designated 1, for preparing thin films of various formulations of
materials on substrates. In general, the workstation includes
storage and delivery apparatus generally indicated at 5 for storing
a supply of substrates 7 held by substrate holders 11, an optional
printing apparatus 15 for printing identifying indicia on each
substrate holder 11, and transfer apparatus 21 for receiving
substrate holders delivered by the storage and delivery apparatus 5
and transferring them to a pick-up station 25. The workstation also
includes a programmable robot 29 capable of moving objects along X,
Y and Z-axes. The robot 29 includes a first arm 33 which carries a
gripping mechanism 35 for gripping a substrate holder 11 at the
pick-up station 25 and transferring the holder to a film-forming
station 39, and a fluid dispenser 41 for dispensing fluid onto a
substrate 7 at the film-forming station. The robot 29 also includes
a second arm 45 which carries a suction assembly 49 for removing
and replacing caps on vials containing film-forming fluids to be
dispensed onto substrates 7 at the film-forming station 39, and a
doctor blade assembly 51 for spreading fluids on the substrates to
form films of materials to be tested. A vacuum system 55 is
provided at the film-forming station for holding a corresponding
number of substrates 7 in fixed position during the film forming
process, following which the substrate holders 11 and substrates
therein are transported by the grippers 35 on the first arm 33 back
to the pick-up station 25 for transfer to the storage and delivery
apparatus 5. The storage and delivery apparatus 5 then transports
each substrate holder 11 containing a substrate 7 with one or more
films formed thereon, to an output rack. Thereafter, the films are
subjected to various tests to determine properties and/or
characteristics of the film materials. These various pieces of
equipment are described in more detail below.
[0035] The storage and delivery apparatus 5 is of conventional
design, e.g., a BenchCel.RTM. micro-plate handling system sold by
Velocity11, 3565 Haven Avenue, Menlo Park, Calif. 94025-1009. The
apparatus comprises a number of input and output racks 61 (e.g.,
four racks are shown) for holding substrate holders 11 containing
substrates 7, and a robotic transporter 65. The transporter 65
operates to unload substrate holders 11 (containing clean
substrates 7) from the input racks 61 for processing through a
film-preparation workflow to be described, and thereafter to load
the substrate holders (containing substrates with films formed
thereon) into the output racks.
[0036] The printing apparatus 15 is of conventional design, e.g., a
VCode.RTM. printing system sold by Velocity11, 3565 Haven Avenue,
Menlo Park, Calif. 94025-1009, and is suitable for printing
identifying indicia, e.g., bar code, on each substrate holder 11.
The indicia identify the substrate 7 held by the substrate holder
11 to facilitate tracking of the substrate as it moves through the
film formation and process and subsequent testing or other
procedures. If desired, the printing apparatus can be removed or
replaced by another piece of equipment (e.g., incubator, freezer,
etc.).
[0037] The transfer apparatus 21 includes a platform 69 for
receiving a substrate holder 11 from the robotic transporter 65.
The substrate holder is placed on the platform in a generally
"landscape" orientation in which the longitudinal axis of the
holder is generally parallel with the direction of travel of the
robotic transporter (FIG. 1). The transfer apparatus 21 operates to
rotate the substrate holder 11 ninety degrees and to position the
holder at the pick-up station 25 in a generally "portrait"
orientation where it is ready for pick-up by the gripping mechanism
35 of the robot 29 (FIG. 2).
[0038] The robot 29 is a 3-axis programmable system capable of
moving objects along X, Y and Z-axes, the X and Y-axes typically
being generally horizontal and the Z-axis generally vertical. As a
result, an object can be moved in a predetermined manner to
essentially any X/Y/Z position within the working range of the
system. For convenience, dimensions and directions along the X, Y
and Z-axes shown in FIG. 1 will be referred to herein as "X"
dimensions/directions, "Y" dimensions/directions and "Z"
dimensions/directions, respectively.
[0039] The robot 29 includes the aforementioned first and second
arms 33, 45 movable along a horizontal track 73 corresponding to
the X-axis. (The number of arms may vary, e.g., one, two or three.)
A first vertical rack 75 is mounted on the first arm 33 for
movement along the arm in a Y-direction and for up-and-down
vertical movement relative to the arm in a Z-direction. Similarly,
a second vertical rack 77 is mounted on the second arm 45 for
movement in Y and Z-directions. Users control the robot 29 using a
robotic control system, which typically includes software for both
protocol development and execution. Software useful in the robotic
control system is Renaissance Impressionist.RTM. and Epoch.RTM.
software, available from Symyx Technologies, Inc. (Santa Clara,
Calif.). Renaissance Impressionist.RTM. Software is a general
laboratory automation package for creating and executing laboratory
procedures. For additional detail regarding an exemplary robot and
related accessories, reference may be made to pending
non-provisional application Ser. No. ______, filed on Apr. 27,
2007, claiming priority from provisional application Ser. No.
60/795,788, assigned to Symyx Technologies Inc., both applications
being incorporated by reference herein for all purposes not
inconsistent with this disclosure.
[0040] As illustrated in FIG. 2, the fluid dispenser 41 is mounted
at the lower end of the first vertical rack 75. It is operable to
dispense a predetermined quantity or quantities of fluid onto a
substrate 7. The gripping mechanism 35, also carried by the first
arm 33, is attached to the lower end of a support 81 which is
connected at its upper end to the rack 75. The gripping mechanism
35 comprises a plurality of grippers 85 (e.g., four are shown in
FIG. 3) operated by suitable means to move between open and closed
positions to grip and release a substrate holder 11. The fluid
dispenser 41 and gripping mechanism 35 are moved by the robot 29 in
X, Y and Z-directions in a predetermined (programmed) manner.
[0041] The vacuum system 55 at the film-forming station 39
comprises a vacuum plate 91 and a plurality of vacuum devices or
chucks 95 on the plate, three such chucks being shown in FIG. 4.
(The number of chucks can vary.) Each vacuum chuck 95 comprises a
raised platform 97 having a planar upper surface 99 spaced above
and parallel to the upper surface of the vacuum plate 91 for
supporting a substrate 7, and a pattern of vacuum grooves 101 in
the upper surface 99 which communicate with a suitable source of
vacuum (not shown) for gripping the substrate to the upper surface.
The vacuum plate 91 is supported on a deck panel 105 of the
workstation. In one embodiment, an adjustment system 109 is
provided for adjusting the planarity of the vacuum plate 91 to
maintain the upper substrate-supporting surfaces 99 of the vacuum
chucks 95 in the desired orientation, e.g., in a horizontal plane
parallel to the plane defined by the X/Y-axes of the robot. In
general, the adjustment system 109 comprises a spherical stainless
steel ball 111 (FIG. 5) supporting the vacuum plate 91, a number
(e.g., two) of adjustment screws 113 which thread down through the
vacuum plate 91 into contact with the deck panel 105, and a number
of spring assemblies 117 at spaced locations around the plate for
applying downward forces to the support plate to maintain it
stable. The planarity of the plate 91 can be adjusted by
appropriately threading one or more of the adjustment screws 113 in
one direction or another. This feature allows the planarity of the
vacuum plate 91 and the upper surfaces 99 of the vacuum chucks 95
to be adjusted to match the pitch of the second arm 45 of the robot
29 (which may sag under its own weight), thus maintaining the
thickness of the films formed on the substrates 7 uniform from
place to place on the workstation, e.g., from one vacuum chuck 95
to another.
[0042] Referring to FIG. 6, each substrate holder 11 comprises a
generally rectangular frame 121 having four side walls 123, a
generally planar upper rim 125, an outer periphery 127 defined by
the outer surfaces of the side walls, and an inner periphery 129
defined by the inner surfaces of the side walls. The inner
periphery 129 of the frame defines a first (upper) opening 135
which is sized and configured for receiving a substrate 7. A
shoulder or ledge 141 protrudes laterally inward from the inner
periphery 129 of the frame. The shoulder 141 has a generally planar
upper surface 143 spaced a distance 147 below the upper rim 125 of
the frame for supporting the substrate in the first frame opening
135. The shoulder 141 has an inner periphery 151 which defines a
second (lower) opening 155 which is sized and configured for
receiving a substrate support, e.g., at least the upper surface 99
of a respective vacuum chuck 95. In one embodiment, the lower
opening 155 is smaller than the first (upper) opening in both the X
and Y-directions (i.e., width and length) but other configurations
are possible.
[0043] In the sequence illustrated in FIGS. 7-9, the holder 11 and
a substrate 7 therein may be moved by the robot 29 (i.e., the
gripper mechanism 35) to a position above a selected vacuum chuck
95 and then lowered to a position in which at least upper portion
of the vacuum chuck 95 is received in the second (lower) opening
155 of the substrate holder 11 and the substrate 7 is deposited on
the top surface 99 of the vacuum chuck 95. A number of feet 161
project down from the bottom of the frame 121 for contact with the
vacuum plate 91 to support the frame in a position spaced above the
plate to allow the grippers 85 to disengage from the frame and
later to re-engage the frame for removal of the frame and substrate
therein from the vacuum chuck 95. As illustrated in FIG. 6, the
substrate holder 11 has four such feet 161 at the corners of the
frame, each being secured by a fastener 163 or other suitable
means. The lower ends of the feet 161 are received in registration
sockets 171 (FIG. 4) in the vacuum plate 91 to hold the substrate
holder 11 in a fixed X/Y position relative to the plate.
[0044] As shown in FIG. 10, the substrate holders 11 are configured
for stacking one on top of another. In this regard, the upper rim
125 of the frame 121 of each holder has registration sockets 175
for receiving the feet of a substrate holder stacked on top of it.
As a result, a stack of holders is compact and yet stable. Further,
the feet 161 and sockets 175 are vertically dimensioned to maintain
a minimum spacing 177 between adjacent frames 121. This spacing
permits air to flow freely between the frames to promote drying of
the films on the substrates 7. By way of example but not
limitation, the spacing may be 0.125 in.
[0045] In one embodiment, the first (upper) opening 135 and
shoulder 141 of the substrate holder 11 are configured for holding
a substrate 7 having length (Y) and width (X) dimensions
corresponding to those of a standard rectangular micro-titer plate
(about 4.75 in. long, 3.085 in wide, and about 0.060-0.125 in.
thick). Further, the second (lower) opening 155 of the substrate
holder 11 is configured for receiving a vacuum chuck 95 of a
particular size. However, it will be understood that the first
(upper) opening 135 and shoulder 141 can have different sizes and
shapes for holding substrates having corresponding sizes and
shapes. Similarly, the second (lower) opening 155 can have
different sizes and shapes for receiving substrate supports (e.g.,
vacuum chucks 95) having corresponding sizes and shapes.
[0046] The substrate 7 may be of any suitable material having any
thickness. By way of example but not limitation, the substrate may
be of glass, aluminum or paper. In any case, when the substrate 7
is deposited on a vacuum chuck 95 and the substrate holder 11 is
resting on the vacuum plate 91, the top surface of the substrate
should lie in a plane above the upper rim of the frame 121. In
applications where the substrate 7 is especially thin (e.g.,
paper), a perforated adaptor plate 181 (FIG. 4) can be positioned
in the substrate holder 11 below the substrate to increase the
overall thickness of the substrate/adaptor combination an amount
sufficient to raise the top surface of the substrate 7 to the
desired level. (Perforations are provided in the adaptor plate 181
to permit vacuum gripping of the substrate by the vacuum chuck
95.)
[0047] Referring to FIGS. 11 and 12, the suction assembly 49
carried by the second arm 45 comprises a vertical rail 201 spaced
from and generally parallel to the Z-rack 77 on the second arm. The
rail 201 is supported at its upper end by an upper support 205
affixed to the second arm 45 and at its lower end by a lower
support 207 affixed to a bracket 211 of the doctor blade assembly
51. A carriage 215 carrying a suction cup device 217 is mounted for
sliding movement up and down along the rail 201. The suction cup
device 217 is connected by a flexible vacuum line 221 to a suitable
source of vacuum. The carriage 215 is moved by a linear actuator
such as a pneumatic cylinder 223 having an upper end attached to
the upper support 205 and an extensible and retractable rod 227
pivotally attached at 231 to the carriage. The arrangement is such
that extension of the rod 227 moves the carriage 215 down along the
rail 201 to lower the suction cup device 217 and retraction of the
rod moves the carriage up along the rail to raise the suction cup
device. The range of movement of the carriage 215 is controlled by
the stroke of the cylinder 223, which is in turn controlled by the
same software which controls the robot 29. In its lowered position,
the suction cup device 217 is at a level below that of the doctor
blade assembly 51.
[0048] FIGS. 13 and 14 illustrate the doctor blade assembly 51,
also carried by the second arm 45 of the robot 29, for forming one
or more films on a substrate 7 positioned on a vacuum chuck 95. In
general, the doctor blade assembly 51 comprises the bracket 211
attached to the lower end of the second vertical rack 77 of the
robot 29, a doctor blade 233 with adjustable feet 235, and a
flexible coupling 239 connecting the doctor blade to the bracket.
Each of these components is described in detail below.
[0049] In the embodiment shown in FIG. 13, the bracket 211 has a
generally vertical body 241 and upper and lower arms 243, 245
projecting generally horizontally from the body. The upper arm 243
comprises an inner part 243A and a separate outer part 243B which
define an opening 247 for receiving the lower end of the Z-rack 77.
The inner and outer parts 243A, 243B are connected by fasteners 251
which can be loosened to allow the bracket 211 to be mounted on and
removed from the rack 77 and tightened to clamp the bracket to the
rack. The bracket may have other configurations.
[0050] The flexible coupling 239 connecting the doctor blade 231 to
the bracket 211 comprises a spring member 251 (FIG. 14) having a
cylindrical side wall 253 with upper, lower and central regions
253A, 253B, 253C, and a central bore 257 extending from one end of
the member 251 to the other along a longitudinal axis 261 extending
in the Z-direction. The spring member 251 is preferably formed from
metal (e.g., stainless steel). In one embodiment, the upper and
lower regions 253A, 253B of the side wall are substantially
non-compressible in the Z-direction, and the central region 253C of
the side wall is formed as a compressible helical spring 255. When
compressed, the spring 255 functions to exert a downward force on
the doctor blade 231 sufficient to maintain the adjustable feet 235
on the doctor blade in contact with the substrate 7 as the doctor
blade moves across the substrate during the film-forming process.
An exemplary force found to be suitable in some applications is
about 4.0 lbs (.+-.10%) at 0.030 in. of spring compression. One
source of such springs is Helical Products Co., Inc. of Santa
Monica, Calif. A desirable property of the spring 255 is that its
stiffness increases in a direction normal to the longitudinal axis
261 of the spring. In other words, the spring becomes stiffer as it
bends. The advantage of this property will become apparent later.
The spring member 251 may have other configurations without
departing from the scope of this invention.
[0051] In one embodiment, the spring member 251 of the flexible
coupling 239 has releasable connections with both the bracket 211
and the doctor blade 233. The releasable connection with the
bracket 211 comprises a cylindrical upper pin 231 having an upper
end attached to the bracket, as by friction fit of the upper end of
the pin in a bore 275 in the lower arm 245 of the bracket. A
quick-release locking mechanism 277 is provided for securing the
pin in the bore 275. The mechanism 277 comprises a shaft 281
threaded in a bore 283 in the bracket, and a knob 285 for rotating
the shaft into and out of contact with the pin 271. The lower end
of the upper pin 271 has a sliding fit in the upper end of the
longitudinal bore 257 of the spring member. As shown in FIG. 15,
the upper region 253A of the spring member 251 comprises two
opposing sections 253A1 and 253A2 separated by vertical slots 291
extending down from the top of the member. The two sections are
resiliently deformable by a clamping screw 295 which bridges the
sections at one side of the spring member 251. The arrangement is
such that tightening the screw 295 draws the two sections 253A1,
253A2 toward one another to clamp against the upper pin 271 and
loosening the screw allows the sections to move back toward their
relaxed condition in which the two sections are spaced farther
apart to allow the spring member 251 to be removed from the upper
pin 271. Thus, by tightening the screw 295, the spring member 251
can be fixedly secured to the upper pin 271. Similarly, the
releasable connection between the spring member 251 and the doctor
blade 233 comprises a lower pin 301 having a lower end attached to
the doctor blade, as by a press fit of the pin in a bore 305
extending down from a top surface 307 of the body of the doctor
blade, and an upper end received in the lower end of the
longitudinal bore 257 of the spring member 251. Like the upper
region 253A, the lower region 253B of the spring member 251
comprises two opposing sections separated by vertical slots (not
shown) extending up from the bottom of the member. The two sections
are resiliently deformable by a clamping screw 321 which bridges
the sections at one side of the spring member 251 (FIG. 15). The
arrangement is such that tightening the screw 321 draws the two
sections toward one another to clamp against the lower pin 301, and
loosening the screw allows the sections to move back toward their
relaxed condition in which the two sections are spaced farther
apart to allow the doctor blade and the spring member to be
separated. Thus, by tightening the screw 321, the spring member 251
can be fixedly secured to the lower pin 301. Other types of
releasable connections may be used. When fully assembled, the upper
and lower pins 271, 301 are generally co-axial with the central
longitudinal axis 261 of the spring member 251, and the lower end
of the upper pin and the upper end of the lower pin are separated
in the area of the spring 255 by a vertical distance, e.g., the
length of the spring (see FIG. 14).
[0052] As illustrated in FIGS. 15 and 16, the doctor blade 233
comprises an elongate body 331 of suitable material (e.g., a block
of stainless steel) having a bottom surface 333, a top surface 307,
opposite ends 337, a leading front side 339 and a trailing back
side 341. (The terms "leading" and "trailing" are with respect to
the direction of travel of the doctor blade as it moves in the
Y-direction to form a film on a substrate 7.) The adjustable feet
235 are mounted on opposite ends 337 of the body 331 and extend a
predetermined distance down below the bottom surface 333 of the
body. The feet 235 contact a substrate 7 upon which a film is to be
formed and function as spacers to space the body 331 of the doctor
blade 233 above the substrate. In the embodiment of FIG. 17, the
bottom surface 333 of the body of the doctor blade comprises two
faces, i.e., a planar leading face 333L which slopes down from the
front leading side 339 of the body and a planar trailing face 333T
which extends from the leading face to the back surface of the
body. The slope of the leading face 333L functions to gradually
reduce the thickness of the fluid being spread as the doctor blade
233 moves across the substrate. When the feet 235 on the doctor
blade 233 are in contact with the substrate 7, the trailing rear
face 333T extends generally parallel to the substrate 7 and is
spaced above the substrate by a distance or "gap" 351 (FIG. 18)
generally corresponding to the thickness of the film to be formed.
(It will be noted that the formed film thickness will be less than
the set gap 351, but there is a direct correspondence between the
size of the gap and the thickness of the film in the sense that the
thickness of the film increases and decreases as the size of the
gap increases and decreases.)
[0053] Each of the two feet or spacers 235 on the doctor blade 233
comprises a relative thin planar four-sided member (also designated
235) having top and bottom edges 355, 357 and inclined front and
back edges 359, 361, the bottom edge 357 being the edge that
contacts a substrate 7. The feet are preferably of a relatively
hard material (e.g., 60-75 Shore D durometer) having a low
coefficient of friction (e.g., 0.25 on dry steel). One such
material is reinforced PTFE sold under the trademark Rulon.RTM..
The feet 235 are secured in position by mechanisms 371 which permit
adjustment of the spacers in the Z-direction to vary the distance
which the feet extend below the bottom surface of the doctor blade,
i.e., the gap 351 corresponding to the desired film thickness. In
the embodiment of FIGS. 15 and 16, each such mechanism 371
comprises a clamp member 373 having two vertically spaced holes 375
in alignment with a generally vertical (Z-axis) slot 379 in a
respective foot 235 for receiving fasteners 381. The fasteners pass
through the holes and the slot and are threaded into holes 385 in
the ends 337 of the body 331 of the doctor blade. The fasteners 381
may be loosened to adjust the position of the foot 235 generally
along the Z-axis according to the desired thickness of film to be
formed on the substrate 7, and then tightened down on the clamp
member 375 to clamp the foot 235 in adjusted position. The slot 379
in the foot 235 has a length sufficient to provide the necessary or
desired range of adjustment (e.g., 1-50 mils) along the Z-axis.
Further, the slot 379 is desirably somewhat wider than the shanks
of the fasteners 381 to permit limited pivotal adjustment (e.g.,
plus or minus about 3.0 degrees) of the foot about an axis
extending endwise of the doctor blade body 331 to insure that the
bottom edge 357 of the foot is in the desired orientation (e.g.,
parallel) relative to the trailing bottom face 333T of the doctor
blade 233. Other adjustment mechanisms may be used for adjustably
securing the feet 235 to the body 331 of the doctor blade. Further,
the feet may have other configurations without departing from the
scope of this invention.
[0054] As noted previously, the flexible coupling 239 functions to
exert a downward force on the doctor blade 233 sufficient to
maintain the feet of the doctor blade in constant contact with the
substrate 7 during the film-forming procedure so that the thickness
of the film remains uniform. As the doctor blade moves across the
substrate 7 (in the Y-direction as shown in FIGS. 18 and 19),
significant upward forces are generated on the bottom surface 333
of the doctor blade and a bending moment is applied to the flexible
coupling 239. This moment can cause intermittent bending and
straightening of the spring 255 along its longitudinal axis 261 and
resultant intermittent stop-and-go movement ("chatter") of the
doctor blade as it slides on its feet 235 across the substrate. To
reduce or prevent such chatter, the doctor blade 233 is configured
so that the flexible coupling 239, and the spring 255 in
particular, assumes a slight bend along its longitudinal axis 261
when the feet 235 are moved into full contact with the substrate 7.
This bend can be seen by comparing FIG. 17 in which the feet 235 of
the doctor blade are spaced above the substrate 7, and FIG. 18 in
which the feet are in full contact with the substrate.
[0055] In FIG. 17 the spring 255 of the spring member 251 is in a
relaxed condition and the upper and lower pins 271, 301 are in
Z-alignment with the spring member along axis 261. Further, the
body 331 of the doctor blade 233 assumes a position in which its
top surface 307 lies in a plane P1 perpendicular to the central
longitudinal axis 261 of the spring member 251, and the trailing
bottom face 333T of the doctor blade lies in a plane P2 plane which
is oblique to the longitudinal axis of the spring member.
Specifically, the plane P2 slopes upward toward the front leading
side 339 of the doctor blade at a relatively small angle A (e.g.,
about three degrees) relative to the Y-axis corresponding to the
horizontal plane of the substrate 7. The front and back sides 339,
341 of the body 331 are generally parallel to one another and
perpendicular to plane P2. The lower edges 357 of the feet 235 lie
in a plane P3 spaced below and parallel to the plane P2 at the same
angle A relative to the Y-axis. When the doctor blade 233 is moved
by the robot 29 to bring the feet 235 of the doctor blade into
contact with the substrate 7, the doctor blade will pivot or rock,
as permitted by the flexible coupling 239, to the position shown in
FIG. 18 where the feet are in full contact with the substrate, that
is, a position in which the lower edges 357 of the feet 235 and the
trailing face 333T on the bottom of the doctor blade are parallel
to the substrate. In this position, the spring 255 deforms or bends
along its longitudinal axis 261 to a position in which the lower
end of the spring is offset in a rearward direction (to the left in
FIG. 18) from the upper end of the spring, and in which the
longitudinal axis of the lower pin 301 is skewed at the same angle
A with respect to the longitudinal axis (Z-axis) of the upper pin
271. As noted previously, the bend in the spring 255 causes the
stiffness of the spring to increase. As a result, the spring is
more resistant to deformation as the doctor blade moves forward
along the substrate 7 in the Y-direction to form the film, thus
reducing or preventing any chatter of the doctor blade. Further,
the downward force generated by bent spring 255 has a vertical
component and a horizontal component so that the force is directed
more toward the rear of the doctor blade where the film-forming gap
351 is narrowest and the upward forces exerted on the doctor blade
are the greatest. The magnitude and direction of force applied to
the doctor blade can be varied by changing, among other things, the
characteristics of spring 255 and/or the angle A.
[0056] In operation, the robotic transporter 65 unloads a substrate
holder 11 from an input rack 61. The holder 11 contains a clean
substrate 7 supported on the shoulder 141 of the frame 121 in the
upper opening 135 of the holder. The transporter carries the holder
and the substrate therein to the printing apparatus 15 where
suitable identifying indicia are printed on the holder, following
which the transporter delivers the holder to the transfer apparatus
21 for transfer to the pick-up station 25. The frame 121 of the
substrate holder 11 is then gripped by the gripping mechanism 35,
lifted, conveyed to a location immediately above one of the vacuum
chucks 95 (FIG. 7), and lowered to the position shown in FIG. 8 in
which the upper portion of the chuck is received in the second
(lower) opening 155 in the frame and the substrate 7 is deposited
on the vacuum surface 99 of the chuck. The frame 121 continues to
be lowered (FIG. 9) until the feet 161 of the frame are received in
the registration sockets 171 in the vacuum plate 91 (FIG. 4). In
this position, the top rim 125 of the frame 121 is below the upper
surface of the substrate 7 so that it does not interfere with the
doctor blade 233 during the film-forming process. This sequence is
repeated to deposit additional substrates on one or more of the
remaining chucks 95.
[0057] The suction assembly 49 is used to remove the cap from a
vial or other receptacle containing fluid to be used to make a
film. After the cap is removed, fluid is aspirated from the vial by
the fluid dispenser 41 and deposited on a substrate 7 secured to a
vacuum chuck 95. Fluid from the same vial or one or more different
vials can be deposited on one or more substrates on the other
chucks 95, if desired. With vacuum holding the substrate 7 securely
in place on the chuck 95, the doctor blade 233 is positioned on the
substrate with the feet 235 of the doctor blade in full contact
with the substrate and forced against the substrate by the spring
member 253 of the flexible coupling 239. As explained above, the
spring 255 of the spring member 253 is slightly bent to resist
further bending deformation as the doctor blade 233 is advanced in
the Y-direction over the substrate to form a film (FIG. 19). This
process can be repeated for the same substrate to form more than
one film on the substrate. The doctor blade can also be used to
form films on one or more substrates positioned on the other chucks
95.
[0058] After the film or films are formed on a substrate, the
vacuum holding the substrate in place is removed and the gripping
mechanism 35 grips the frame 121 and lifts the substrate holder 11
off the vacuum chuck 95. In doing so, the inside shoulder or ledge
141 of the frame moves up to engage the substrate 7 so that the
substrate holder and substrate contained therein can be removed
from the vacuum device as a unit. The holder and substrate therein
are then transported by the robot 29 back to the pick-up station 25
for transfer to the transport robot 65 and delivery to an output
rack 61 for storage and further processing (e.g., film
testing).
[0059] FIGS. 20-23 illustrate a tool, generally designated 401, for
setting/adjusting the gap 351 of the doctor blade 233. The tool 401
comprises a base 403, a block 407 with a vertical planar reference
face 409 machined to a precise flatness (.+-.0.0002 in.), first and
second hold-down clamps 415, 417 with conventional over-center
toggle levers 421, and a device generally designated 425 for
positioning the doctor blade 233 relative to the block 407 for
adjusting the distance the feet 235 project below doctor blade to
set the "gap" 351 according to the desired film thickness. The base
403 of the tool has an upper planar horizontal surface 427
supporting the reference block and a sloping surface 431 which
slopes at an angle (corresponding to angle A above) from the right
end of the base down toward a step 433 up to the upper surface 427.
The positioning mechanism 425 comprises a cylindrical member 441
open at both ends. The member defines a bore 443 having a length
dimensioned for receiving the upper pin 271 and the spring member
251 of the doctor blade assembly 51. The internal diameter of the
member 441 is dimensioned for snugly receiving the spring member
251. A sleeve 451 is mounted on the cylindrical member 441 for
sliding movement in an axial direction, the range of such movement
being limited by a pin 453 projecting from the cylindrical member
into a slot 455 in the sleeve. A coil spring 461 surrounds the
cylindrical member 441 and reacts against an annular abutment 463
contacting a flange 465 at the right end of the member (FIG. 22) to
urge the sleeve 451 in a direction toward the left end of the
cylindrical member 441. Two arms 471 extend out from the sleeve 451
at opposite sides of the sleeve. Two fingers 473 are provided at
opposite ends of the arms and project generally parallel to the
longitudinal axis of the sleeve 451 and cylindrical member 441. The
spacing between the fingers 473 is only slightly greater than the
length (end-to-end) dimension of the body 331 of the doctor blade
233 so that the doctor blade fits snugly between the fingers.
[0060] If the "gap" 351 is to be adjusted, the doctor blade 233 and
flexible coupling 239 are removed as a unit from the C-clamp 211,
and the fasteners 381 of the adjustment mechanisms 371 holding the
feet 235 on the doctor blade in fixed position are loosened. The
flexible coupling 239 is inserted into the cylindrical member 441
of the positioning mechanism 425 to the position shown in FIGS.
20-22 in which the doctor blade 233 is received between the fingers
473 with its back side 341 face down and flat against the upper
surface 427 of the base and its trailing bottom face 333T adjacent
but spaced from the planar reference face 409 of the block 407. The
doctor blade is held in this position by the first hold-down clamp
415. The abutment member 43 at the right end of the cylindrical
member 441 abuts against a stop 481 of the second hold-down clamp.
One or more feeler gages 485 (shims of known thickness) having a
thickness corresponding to the desired gap 351 are inserted up
through an opening 487 in the base 403 to a position between the
reference face 409 and bottom surface 333 of the doctor blade 233.
After moving the toggle lever 421 of the second hold-down clamp 417
to it over-center position (FIG. 20), an adjustment ring 491 is
rotated to move a compliant member 493 and the stop 481 of the
second hold-down clamp into engagement with the cylindrical member
441. (The adjustment ring 491, compliant member 493 and stop 481
are secured together by a fastener 495.) Continued rotation of the
adjustment ring 491 causes the cylindrical member 441 to move to
the left to press the doctor blade 233 tightly against the gage(s)
485 and the gage(s) tightly against the reference surface 409 of
the block 407 to set the "gap" 351 of the doctor blade to a
dimension corresponding to the thickness of the gage(s). During
this movement, the fingers 473 on the arms 473 of the positioning
mechanism 425 are urged by coil spring 461 into contact with the
feet 235 of the doctor blade 233 such that the feet are pressed
against the planar reference surface of the block. With all parts
in this final position (FIG. 23), the fasteners 381 of the
adjustment mechanisms 371 are tightened to secure the feet in
adjusted position to set the "gap" 351 between the block and the
gap-defining face 333T of the doctor blade.
[0061] After the gap 351 is set, the hold-down clamps 415, 417 are
released and the doctor blade 233 and flexible coupling 239 are
removed from the tool 401. The flexible coupling 239 is then
reattached to the bracket 211. If the bracket was removed from the
robot 29, it is quickly remounted using the quick-release mechanism
277. It will be apparent, therefore, that the "gap" 351 can be
quickly adjusted as needed or desired.
[0062] The adjustment feature described above is advantageous
because the feet 235 (i.e., the spacers) of the doctor blade can be
adjusted to vary the predetermined distance or "gap" 351
independent of the type or thickness of the substrate 7. Further,
the gap 351 can be adjusted when the doctor blade 233 is removed
from the robot 29 and without using a substrate 7. As a result, the
same doctor blade 233 can be rapidly, conveniently and precisely
adjusted to form films of different thicknesses. This represents an
improvement over conventional doctor blade designs.
[0063] When introducing elements of the present invention or the
preferred embodiment(s) thereof, the articles "a", "an", "the" and
"said" are intended to mean that there are one or more of the
elements. The terms "comprising", "including" and "having" are
intended to be inclusive and mean that there may be additional
elements other than the listed elements.
[0064] In view of the above, it will be seen that the several
objects of the invention are achieved and other advantageous
results attained.
[0065] As various changes could be made in the above constructions
and methods without departing from the scope of the invention, it
is intended that all matter contained in the above description and
shown in the accompanying drawings shall be interpreted as
illustrative and not in a limiting sense.
* * * * *