U.S. patent application number 11/804566 was filed with the patent office on 2007-09-20 for apparatus for electroplating an article.
Invention is credited to Steven P. Glassman.
Application Number | 20070215457 11/804566 |
Document ID | / |
Family ID | 38516630 |
Filed Date | 2007-09-20 |
United States Patent
Application |
20070215457 |
Kind Code |
A1 |
Glassman; Steven P. |
September 20, 2007 |
Apparatus for electroplating an article
Abstract
An apparatus for electroplating an article, such as a printed
circuit board, includes a tank filled with electrolytic solution, a
clamp for retaining the article fixed in place within the solution
and a movable roller assembly disposed within the solution. The
roller assembly includes a pair of vertically disposed, parallel
rollers that are rotatably coupled to a rigid frame, with one
roller preferably being spring biased towards the other roller. In
use, the application of electrical current causes metal ions
present in the solution to plate out on the article. To promote
greater plating within through-holes or other similar surface
depressions in the article, the roller assembly is linearly
displaced by a motor-driven linkage so that the pair of rollers
squeegee opposing surfaces of the article.
Inventors: |
Glassman; Steven P.;
(Marlborough, MA) |
Correspondence
Address: |
KRIEGSMAN & KRIEGSMAN
30 TURNPIKE ROAD, SUITE 9
SOUTHBOROUGH
MA
01772
US
|
Family ID: |
38516630 |
Appl. No.: |
11/804566 |
Filed: |
May 18, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11606629 |
Nov 30, 2006 |
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11804566 |
May 18, 2007 |
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10856505 |
Jun 1, 2004 |
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11606629 |
Nov 30, 2006 |
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Current U.S.
Class: |
204/194 ;
205/102 |
Current CPC
Class: |
H05K 2203/1518 20130101;
C25D 17/005 20130101; C25D 5/22 20130101; H05K 3/423 20130101; H05K
2203/0143 20130101; C25D 17/06 20130101 |
Class at
Publication: |
204/194 ;
205/102 |
International
Class: |
C25D 17/00 20060101
C25D017/00; C25D 5/00 20060101 C25D005/00 |
Claims
1. An apparatus for electroplating an article, the article
including substantially flat front and rear surfaces, the apparatus
comprising: (a) a tank shaped to define an interior cavity; (b) a
clamp adapted to fixedly support the article within the interior
cavity of the tank; (c) a roller assembly adapted to squeegee the
front and rear surfaces of the article; and (d) a linkage for
linearly displacing the roller assembly within the interior cavity
of the tank.
2. The apparatus as claimed in claim 1 wherein the roller assembly
comprises, (a) a rigid frame, and (b) a pair of parallel rollers
coupled to the rigid frame.
3. The apparatus as claimed in claim 2 wherein each of the pair of
parallel rollers is vertically disposed and is adapted to contact a
corresponding surface on the article in order to squeegee material
that has accumulated on the surface during the electroplating
process.
4. The apparatus as claimed in claim 3 wherein each of the pair of
parallel rollers can spin freely relative to the rigid frame.
5. The apparatus as claimed in claim 3 wherein the pair of parallel
rollers is spaced apart a fixed distance.
6. The apparatus as claimed in claim 3 wherein the spacing between
the pair of parallel rollers can be adjusted.
7. The apparatus as claimed in claim 6 wherein at least one of the
pair of parallel rollers is spring biased towards the other of the
pair of parallel rollers.
8. The apparatus as claimed in claim 3 wherein each roller
comprises, (a) a core, and (b) a sleeve disposed over the core.
9. The apparatus as claimed in claim 8 wherein the core is
constructed out of a titanium-sleeved copper.
10. The apparatus as claimed in claim 9 wherein the sleeve is
constructed out of polyvinyl alcohol (PVA).
11. The apparatus as claimed in claim 1 wherein the apparatus
additionally comprises, (a) a direct current (DC) power supply
which comprises a positive terminal and a negative terminal, (b) a
cathode bar, the clamp being conductively coupled to the negative
terminal of the DC power supply through the cathode bar, and (c)
one or more metal rods disposed within the interior cavity of the
tank, each of the one or more metal rods being electrically
connected to the positive terminal of the DC power supply.
12. The apparatus as claimed in claim 1 wherein the linkage
comprises, (a) a motor, (b) a rotatable disk fixedly mounted on the
motor, (c) a travel board slidably mounted on the rotatable disk,
and (d) a rail fixedly connected to the travel board, the rail
being fixedly connected to the roller assembly.
13. The apparatus as claimed in claim 12 wherein the tank comprises
a flat bottom panel and four side panels that together define the
interior cavity.
14. The apparatus as claimed in claim 13 wherein the tank
additionally comprises a pair of fixedly mounted support
blocks.
15. The apparatus as claimed in claim 14 wherein the pair of
support blocks limit the rail to displacement along a linear
path.
16. The apparatus as claimed in claim 15 wherein the rotatable disk
includes a fixed pin which is sized and shaped to protrude through
a longitudinal slot formed in the travel board.
17. A method of manufacturing an article, the article including
substantially flat front and rear surfaces; said method comprising
the steps of: (a) electroplating the article, the electroplating
step resulting in a layer of metal being deposited on the front and
rear surfaces of the article, and (b) squeegeeing at least a
portion of the layer of metal deposited on the front and rear
surfaces of the article using a roller assembly.
18. The method as claimed in claim 17 wherein the roller assembly
is linearly movable.
19. The method as claimed in claim 18 wherein the roller assembly
comprises, (a) a rigid frame, and (b) a pair of parallel rollers
coupled to the rigid frame.
20. The method as claimed in claim 19 wherein, as part of the
squeegeeing step, each of the pair of parallel rollers contacts a
corresponding surface on the article.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation-in-part of U.S.
patent application Ser. No. 11/606,629, filed Nov. 30, 2006 which,
in turn, is a continuation of U.S. patent application Ser. No.
10/856,505, filed Jun. 1, 2004, both of said applications being
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates generally to electroplating
equipment and more particularly to equipment used to electroplate
articles which include holes and/or surface depressions.
[0003] Electroplating is a well-known and widely used process which
uses electrical current to deposit a thin layer of metal with some
particular property (e.g., conductivity, abrasion and wear
resistance, corrosion protection, lubricity, improvement of
aesthetic qualities, etc.) onto an article that lacks said
property.
[0004] Specifically, in one well-known form of electroplating,
electrodes are immersed in a tank filled with an electrolytic
solution that serves to create a closed electrical circuit
therebetween. One or more of the electrodes (i.e., the electrodes
that are to be plated) serve as the cathode of the circuit and, as
such, are connected to the negative terminal of an external direct
current (DC) power supply, such as a battery or rectifier with
variable voltage and amperage control. The remaining electrodes
(i.e., the electrodes constructed of the particular metal to be
plated onto the cathode) serve as the anode of the circuit and, as
such, are connected to the positive terminal of the DC power
supply. The supply of voltage to the closed circuit causes metal
ions present in the electrolytic solution to lose their charge and
plate out (i.e., accumulate, deposit) on the cathode. The anode
serves to replenish the supply of metal ions in the electrolytic
solution during the plating process.
[0005] Electroplating is commonly utilized during the manufacture
of printed circuit boards to deposit a conductive material, such as
nickel or copper, onto a non-conductive substrate. Upon completion
of the electroplating process, the conductive material deposited on
the substrate is etched in a particular pattern to create a number
of conductive pathways, or traces. In this manner, the conductive
pathways can be used to electrically connect components mounted on
the circuit board.
[0006] Circuit board electroplating is commonly performed in the
following manner. Each circuit board to be plated is attached to a
corresponding conductive frame which is, in turn, connected to the
negative terminal of the power supply. Each frame is then mounted
onto an enlarged tank filled with an electrolytic solution so that
the circuit board is completely immersed within the solution. It
should be noted that each frame is traditionally mounted onto the
tank so that the circuit board extends in a substantially vertical
position, thereby enabling for (1) a greater quantity circuit
boards to be disposed in tank at the same time and (2) easier
access to each circuit board within the tank. With the circuit
board immersed within the solution, one or more pairs of metallic
members (e.g., rods or blocks constructed of copper) are connected
to the positive terminal of the power supply and are similarly
immersed within the electrolytic solution on opposite sides of the
circuit board. Accordingly, with voltage being supplied from the
power source, each circuit board (and its corresponding frame)
serves as the cathode of the closed circuit and each metallic
member serves as the anode of the closed circuit. In this manner,
it is to be understood that the surfaces of the circuit board that
are exposed to metal ions in the electrolytic solution become
plated with conductive material. It should be noted that metal ions
accumulate on the exposed portions of the circuit board until
either (1) the supply of voltage to the circuit is withdrawn or (2)
metal ions no longer remain available in the electrolytic
solution.
[0007] As can be appreciated, printed circuit boards are commonly
provided with a number of holes and/or surface depressions. For
example, many printed circuit boards are provided with a large
quantity of through-holes that extend transversely through the
circuit board substrate, with the barrel of each through-hole being
plated with a conductive material. In this manner, components can
be electrically connected to the printed circuit board by (1)
positioning each lead for the component within a corresponding
through-hole in the circuit board and (2) filling each through-hole
with a conductive material, such as solder.
[0008] The above-described circuit board electroplating process is
commonly used to conductively plate the barrel of through-holes
that extend transversely through the circuit board substrate.
However, it has been found that the effectiveness of electroplating
the barrel of through-holes is compromised due to (1) the
relatively small cross-sectional diameter of each hole and (2) the
limited flow of metal ions in the electrolytic solution through
each through-hole since the longitudinal axis of each hole is
horizontally disposed.
[0009] Various techniques have been incorporated into the
traditional electroplating process to stimulate the flow of
electrolytic solution and thereby increase the amount of metal
plating on an article.
[0010] As an example, it is well-known in the art to periodically
agitate the electrolytic solution to promote greater amounts metal
ion deposition onto an article. Agitation of the electrolytic
solution is often accomplished by displacing one or more air
sparger units within the solution. Each air sparger unit is
commonly constructed using a 0.25-0.50 inch PVC pipe that includes
a plurality of spaced apart holes. In use, clean air (e.g.,
nitrogen) is pumped through the pipe at high pressure and, in turn,
exits through the spaced apart holes in the pipe as bubbles. The
creation of these bubbles serves to help agitate the solution and
break hydrogen gas bubbles that may collect around the board.
[0011] As another example, it is well-known to move and/or vibrate
the article to be plated in order to promote greater amounts of
metal ion deposition. In U.S. Pat. No. 5,167,779 to H. J. Henig,
there is disclosed a process and apparatus for obtaining an
intensive and continuous exchange of electrolyte on the surfaces of
workpieces subjected to chemical or electrolytical treatments
wherein the exchange is achieved by subjecting the workpieces to
strong pulsating oscillations of frequency of at least 1 Hz and of
an amplitude of less than 10 mm, when immersed in the electrolyte.
The vibrations are transmitted from an oscillation generator
mounted on a workpiece carrier, such as a rack or a rotating
dipping drum. These high frequency low amplitude oscillations may
be combined with low frequency, relatively long oscillations
occurring simultaneously. The oscillation generator is arranged on
the individual transportable workpiece carriers. The workpieces may
be boards for printed circuits having through holes or a pourable
mass of parts.
[0012] Although well-known in the art, the techniques described
above for improving metal ion deposition have been found to
introduce a number of notable drawbacks.
[0013] As a first drawback, the above-described techniques have
been found to be inadequate when used to plate the barrel of
circuit board through-holes which extend axially in a horizontal
manner. Specifically, the above-described electroplating techniques
produce a deposition layer on the barrel of each through-hole that
is of limited thickness which, in turn, can jeopardize the quality
of the electrical connection established between electrical
components and the printed circuit board on which the components
are mounted, which is highly undesirable. Consequently, these types
of electroplating processes are often significantly extended until
the deposition layer in each though-holes is adequate. However,
this results in (1) a substantial increase in the deposition layer
on the top and bottom surfaces of the circuit board, (2) an
increase in manufacturing costs, and (3) a greater time
requirement, all of which are highly undesirable.
[0014] As a second drawback, it has been found that the use of
certain agitation units to improve the flow of electrolytic
solution are potentially harmful to the environment, which is
highly undesirable.
SUMMARY OF THE INVENTION
[0015] It is an object of the present invention to provide a new
and improved apparatus for electroplating an article, such as a
printed circuit board, the article including enlarged, flattened
top and bottom surfaces and one or more through-holes extending
transversely therethrough.
[0016] It another object of the present invention to provide an
apparatus as described above which adequately plates the barrel of
each through-hole in the article without significantly increasing
the amount of deposition on each of the top and bottom
surfaces.
[0017] It is yet another object of the present invention to provide
an apparatus as described above which limits the risk of
potentially harmful environmental conditions.
[0018] It is still another object of the present invention to
provide an apparatus as described above which has a limited number
of parts, which is quick and easy to use and which is inexpensive
to manufacture.
[0019] Accordingly, there is provided an apparatus for
electroplating an article, the article including substantially flat
front and rear surfaces, the apparatus comprising (a) a tank shaped
to define an interior cavity; (b) a clamp adapted to fixedly
support the article within the interior cavity of the tank; (c) a
roller assembly adapted to squeegee the front and rear surfaces of
the article; and (d) a linkage for linearly displacing the roller
assembly within the interior cavity of the tank.
[0020] Various other features and advantages will appear from the
description to follow. In the description, reference is made to the
accompanying drawings which form a part thereof, and in which is
shown by way of illustration, a specific embodiment for practicing
the invention. This embodiment will be described in sufficient
detail to enable those skilled in the art to practice the
invention, and it is to be understood that other embodiments may be
utilized and that structural changes may be made without departing
from the scope of the invention. The following detailed description
is therefore, not to be taken in a limiting sense, and the scope of
the present invention is best defined by the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] In the drawings wherein like reference numerals represent
like parts:
[0022] FIG. 1 is a fragmentary, front perspective view of an
apparatus for electroplating an article which has been constructed
according to the teachings of the present invention, the apparatus
being shown with an article attached thereto;
[0023] FIG. 2 is an enlarged, fragmentary, top perspective view of
the roller assembly, support rail and tank shown in FIG. 1; and
[0024] FIG. 3 is an enlarged, front plan view of one of the clamps
shown in FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0025] Referring now to FIG. 1, there is shown an apparatus for
electroplating an article 10, the apparatus being constructed
according to the teachings of the present invention and identified
generally by reference numeral 11. As will be described in greater
detail below, apparatus 11 is specifically designed to ensure
adequate electroplating within any holes, recesses or other similar
types of surface depressions provided in article 10.
[0026] For purposes of simplicity only, article 10 is represented
herein as being in the form of a conventional printed circuit board
that includes enlarged, flattened front and rear surfaces 13-1 and
13-2 as well as a plurality of transversely extending through-holes
15. Furthermore, the inherent benefits associated with apparatus 11
will be described in connection with the plating of the barrel of
each through-hole 15 (i.e., the hole wall) in an efficient
manner.
[0027] However, it is to be understood that apparatus 11 is not
limited to the plating of printed circuit boards. Rather, it is to
be understood that apparatus 11 is designed for use in connection
with any flattened article 10 that commonly electroplated in the
art.
[0028] In addition, it is to be understood that the advantages
inherent in apparatus 11 are not limited to the plating of
transverse through-holes 15 in article 10. Rather, it is to be
understood that apparatus 11 is useful in electroplating other
forms of surface depressions (e.g., grooves, partial holes, etc.)
without departing from the spirit of the present invention.
[0029] Electroplating apparatus 11 comprises a rectangular tank 21,
a pair of clamps 23-1 and 23-2 for supporting the article 10 to be
electroplated, a roller assembly 25 for squeegeeing conductive
material that accumulates on front surface 13-1 and/or rear surface
13-2 of article 10 during the electroplating process, and a
motor-driven linkage 27 for linearly driving roller assembly 25
within tank 21.
[0030] Tank 21 is constructed out of a rigid, durable and
non-conductive material, such as plastic, and includes a flat
bottom panel 29 and four side panels 31-1 through 31-4 that
together define an interior cavity 33. A flat rectangular flange,
or frame, 35 is formed on the free ends of side panels 31 and
defines an open top through which interior cavity 33 can be
accessed. A continuous, horizontal strengthening rib 36 is
additionally formed onto side panels 31 to improve the structural
integrity of tank 21.
[0031] A pair of support blocks 37-1 and 37-2 are fixedly mounted
on opposite ends of flange 35. As seen most clearly in FIG. 2, each
support block 37 is shaped to define a channel 39 which is
generally square-shaped in lateral cross-section. As will be
described further below, blocks 37 serve to both support and guide
a component of linkage 27 during the linear displacement of roller
assembly 25.
[0032] Tank 13 is at least partially filled with an electrolytic
solution (not shown). The electrolytic solution represents any
solution that includes metal (e.g., copper, nickel) dissolved and
suspended in a liquid as a metal ion. As will be described further
below, electrolytic solution creates a closed electric circuit
between the one or more anodes and cathodes of the electroplating
system.
[0033] A pair of cathode bars 43-1 and 43-2 are fixedly mounted
onto opposite ends of flange 35. Each cathode bar 43 is constructed
out of a conductive material, such as copper, and is electrically
connected to the negative terminal of an external DC power supply,
as will be described further in detail below.
[0034] Referring now to FIG. 3, each clamp 23 comprises an
elongated cathode rod 45 that is constructed out of a conductive
material, such as copper. An elongated sleeve 47 is shown mounted
over cathode rod 45 and extends the majority of its length. Sleeve
47 is preferably constructed out of material that serves to
preserve cathode rod 45.
[0035] An L-shaped metal clip 49 and a U-shaped metal hook 50 are
fixedly mounted onto one end of cathode rod 45. Clip 49 is designed
to receive a portion of a cathode bar 43. Clip 49 is additionally
shaped to receive a threaded screw 51. In this manner, with cathode
bar 43 positioned within clip 49, screw 51 can be driven into
frictional engagement with cathode bar 43 to fixedly couple clamp
23 thereto. In this manner, clamp 23 is electrically connected to
cathode bar 43 and, as such, acts as part of the cathode in the
closed circuit. Although not shown herein, it is to be understood
that clamp 23 may be electrically connected to cathode bar 43 by
hanging metal hook 50 directly thereon (rather than using clip
49).
[0036] A plurality of generally C-shaped clips 53 are fixedly
mounted onto sleeve 47 in a spaced apart relationship along its
length. Each clip 53 is sized and shaped to receive an edge of
article 10. Each clip 53 is additionally shaped to receive a
corresponding threaded screw 55. In this manner, with an edge of
article 10 aligned within clips 53, screws 55 can be driven into
frictional engagement with a surface 13 of article 10 to fixedly
couple article 10 thereto. By connecting article 10 to clamp 23 in
this manner, it is to be understood that article 10 acts as part of
the cathode of the closed circuit, as will be described further
below.
[0037] As seen most clearly in FIG. 2, roller assembly 25 comprises
a pair of parallel rollers 57-1 and 57-2 that are connected to a
rigid, stainless steel frame, or collar, 59.
[0038] Preferably, each roller 57 is connected to frame 59 using
one or more fasteners 61 (e.g., an allen screw), fasteners 61
preferably enabling each roller 57 to spin freely relative to frame
59. It is to be understood that, in place of the aforementioned
arrangement, a more complex mechanical device (e.g., a rotatable
bushing or bearing assembly) may be used to enable each roller 57
to spin freely relative to collar 59. At the free end of each
roller 57, a lock bolt 63 is mounted which can be tightened against
frame 59 to prevent each roller 57 from free spinning, which may be
desirable in certain applications.
[0039] Rollers 57 are vertically disposed in a parallel manner and
are spaced apart a fixed distance D (as represented in FIG. 2).
Preferably, at least one roller 57 is spring biased towards the
other. Accordingly, upon the application of a suitable outward
force thereon, the spring biased roller 57 would displace away from
the opposite roller 57, the spring biased roller 57 traveling
within a narrow slot (not shown) provided in collar 59. In this
manner, roller assembly 25 can be used to accommodate articles 10
of varying thicknesses (e.g., in the range of approximately
0.25-0.62 inches), which is highly desirable.
[0040] It should be noted that in place of the spring biased
configuration noted above, roller assembly 25 may be designed such
that each roller 57 can be re-positioned into one of a plurality of
fixed settings to adjust the relative spacing therebetween. Once
disposed in its desired position, each roller 57 can be locked in
place with a fastening element (e.g., a bolt) to maintain constant
spacing therebetween.
[0041] As can be appreciated, the spacing set between the pair of
rollers 57 is dependent upon the particular application and user
preferences. For example, in some applications, it may be desirable
for rollers 57 to barely touch the top and bottom surfaces 13-1 and
13-2 of article 10. In other applications, it may be desirable for
rollers 57 to apply a greater degree of pressure on article 10 so
as to burnish surfaces 13. In this manner, rollers 57 serve to
limit the degree of plating on top and bottom surfaces 13-1 and
13-2 without compromising the efficiency of plating within
through-holes 15, which is highly desirable.
[0042] Each roller 57 comprises a roller core 65 and a sleeve 67
slidably disposed over core 65.
[0043] Core 65 is preferably constructed out of a titanium-sleeved
copper (i.e., a copper core with a titanium outer sleeve). As can
be appreciated, the titanium serves to protect to protect the
copper core from depletion during the plating operation.
[0044] Sleeve 67 is slidably mounted over core 65 in a fitted
relationship relative thereto, with a fastening element (e.g., a
washer and screw) provided at the free end of each roller 57 to
prevent sleeve 67 from sliding off of core 65. Preferably, sleeve
67 is constructed out of polyvinyl alcohol (PVA) which, due to its
sponge-like qualities, would not damage surfaces 13 of article 10.
However, it should be noted that sleeve 67 could be constructed
using other similar materials, such as polypropylene, without
departing from the spirit of the present invention.
[0045] Frame 59 additionally includes a pair of spaced apart,
upwardly extending support rods 69-1 and 69-2 which extend
transversely through a pair of spaced apart support plates 71-1 and
71-2. A fastening device 73 (namely, a collar and threaded screw)
is mounted on the end of each rod 69 to retain plates 71 on rods
69. As will be described further below, support plates 71 are used
to couple roller assembly 25 to linkage 27.
[0046] Referring back to FIG. 1, linkage 27 comprises a motor 74,
an enlarged rotatable disk 75 mounted on motor 74, a travel board
77 coupled to disk 75, and a linearly displaceable rail 79 affixed
to travel board 77. As will be described further in detail below,
linkage 27 serves to linearly displace roller assembly within tank
21 in such a manner so as to squeegee surfaces 13 of article
10.
[0047] Motor 74 is connected to side panel 31-4 of tank 21 by a
support member 81 which serves to space motor 74 adequately away
from side panel 31-4. Motor 74 represents any conventional rotary
motor which is well-known in the art.
[0048] Disk 75 is fixedly mounted onto the output shaft for motor
74. Accordingly, it is to be understood that activation of motor 74
serves to rotate disk 75 (as represented by arrow A in FIG. 1).
Disk 75 is preferably constructed out of rigid and durable material
and includes a pin 83 that extends orthogonally upward from the top
surface of disk 75 at a location other than at its center.
[0049] Travel board 77 is represented herein as being in the form
of a rectangular block that is provided with an elongated,
longitudinal slot 85. As can be seen in FIG. 1, travel board 77 is
mounted on disk 75 such that pin 83 protrudes through slot 85. As a
result, as disk 75 rotates, pin 83 travels back and forth within
slot 85 and, in turn, linearly displaces travel board 77 back and
forth.
[0050] Rail 79 is represented herein as being in the form of an
elongated rod which is generally rectangular in lateral
cross-section. One end of rail 79 is affixed to travel board 77
(e.g., using screws), with the remainder of rail 79 extending
longitudinally above tank 21. As can be seen, rail 79 slidably
protrudes through channel 39 in each support block 37. Accordingly,
it is to be understood that support blocks 37 serve to limit rail
79 to linear displacement above tank 21 (in the direction
represented by arrow B in FIG. 1).
[0051] As seen most clearly in FIG. 2, rail 79 is sandwiched
between plates 71-1 and 71-2 of roller assembly 25 and is held
fixed in place using fastening devices 73. In this manner, it is to
be understood that roller assembly 25 is fixedly mounted onto rail
79.
[0052] As seen most clearly in FIG. 1, electroplating apparatus 11
additionally comprises six copper rods 87 that are fully immersed
within the electrolytic solution, with three rods 87 disposed
vertically against the inner surface of side panel 31-1 and the
other three rods 87 disposed vertically against the inner surface
of opposing side panel 31-3. In this manner, each rod 87 is
disposed roughly the same distance (approximately 10-12 inches)
away from a corresponding surface 13 on article 10.
[0053] Electroplating apparatus 11 further comprises a direct
current (DC) power supply 89, such as battery or rectifier with
variable voltage and amperage control, which is located outside
tank 21. Each copper rod 87 is electrically connected to the
positive terminal 91 for DC power supply 89. In addition, each bar
43 is electrically connected to the negative terminal 93 for DC
power supply 89. For purposes of simplicity only, the
above-described connections are not shown in FIG. 1.
[0054] Although not shown herein, electroplating apparatus 11 also
preferably includes an air sparger unit that is located within tank
13 against the inner surface of bottom panel 29. The air sparger
unit is designed to expel clean air bubbles into electrolytic
solution in order to stimulate electroplating on the intended
article 10.
[0055] Apparatus 11 can be used to electroplate an article 10 in
the following manner. Specifically, with apparatus 11 configured in
the manner described above, the supply of voltage from DC power
supply 89 causes metal ions present in the electrolytic solution to
lose their charge and plate out (i.e., accumulate, deposit) on
article 10, with rods 87 serving to replenish the supply of metal
ions in the solution over time.
[0056] It should be noted that the portions of article 10 that are
directly exposed to the metal ions in solution 41 experience the
greatest degree of plating. Specifically, metal ions present in the
electrolytic solution tend to plate out on front and rear surfaces
13-1 and 13-2 of article 10. In addition, metal ions present in the
electrolytic solution tend to plate out on the barrel of each
through-hole 15.
[0057] During the above-described electroplating process, roller
assembly 25 is driven against front and rear surfaces 13-1 and 13-2
of article 10 to promote greater plating within through-holes 15.
Specifically, activation of motor 74 causes enlarged disk 75 to
rotate about its center which, in turn, serves to linearly displace
travel board 77 back and forth. The linear displacement of travel
board 77 serves to similarly displace rail 79, with support blocks
37 ensuring that the displacement is linear in nature (as
represented by arrow B in FIG. 1). The linear displacement of rail
79 in turn serves to displace roller assembly 25 within tank
21.
[0058] As roller assembly 25 is linearly displaced, sleeve 67 of
each roller 57 is disposed in contact against a corresponding
surface 13 of article 10, the degree of pressure exerted by each
roller 57 against article 10 being largely dependent on the spacing
between rollers 57 (or, if included, the force of any spring used
to bias one roller 57 inward). As the roller assembly 25 advances
linearly, each roller 57 preferably rolls along a corresponding
surface 13 of article. In this manner, it is to be understood that
each roller 57 effectively acts as a squeegee which results in (1)
a reduction in the amount of metal deposition on front and rear
surfaces 13-1 and 13-2 and (2) an increase in the amount of metal
deposition within through-holes 15, which is a principal object of
the present invention.
[0059] The embodiment shown in the present invention is intended to
be merely exemplary and those skilled in the art shall be able to
make numerous variations and modifications to it without departing
from the spirit of the present invention. For example, it is to be
understood that additional roller assemblies 25 could be
implemented into apparatus 11 to allow for simultaneous, efficient
electroplating of multiple articles 10 disposed within the same
tank 21. All such variations and modifications are intended to be
within the scope of the present invention as defined in the
appended claims.
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