U.S. patent application number 10/266061 was filed with the patent office on 2003-04-24 for method for controlling field flow decouple plating and a device thereof.
Invention is credited to Huang, Chuan Fu, Jiang, Shyh Biau, Lee, Dong Liang, Ming, Hsin, Yang, Chi Ming.
Application Number | 20030075449 10/266061 |
Document ID | / |
Family ID | 21679537 |
Filed Date | 2003-04-24 |
United States Patent
Application |
20030075449 |
Kind Code |
A1 |
Jiang, Shyh Biau ; et
al. |
April 24, 2003 |
Method for controlling field flow decouple plating and a device
thereof
Abstract
A method for controlling plating with two independent power
sources, wherein the high voltage power source is used for
controlling the electrical swimming speed of the metal positive
ions while the other is low-voltage power source for being used to
control rate of plating rate. Positively charged metal ions of the
strong electric field in the plating solution can reach to the
negatively charged and unevenly distributed surface of the
extraction negative pole more quickly, which is in turn connected
to the negative of the low voltage power source. The ions aggregate
at the recess of the extraction negative pole surface and waiting
incoming electrons so as to perform electric extraction and produce
uniform plating. The present invention also provides the apparatus
for carrying out the mentioned method and therefore achieves better
plating quality.
Inventors: |
Jiang, Shyh Biau; (Taipei,
TW) ; Lee, Dong Liang; (Keelung, TW) ; Yang,
Chi Ming; (Ilan, TW) ; Ming, Hsin; (Hsinchu,
TW) ; Huang, Chuan Fu; (Taipei, TW) |
Correspondence
Address: |
Connolly Bove Lodge & Hutz LLP
1220 MARKET STREET
P. O. BOX 2207
WILMINGTON
DE
19899
US
|
Family ID: |
21679537 |
Appl. No.: |
10/266061 |
Filed: |
October 7, 2002 |
Current U.S.
Class: |
205/80 ; 204/242;
204/290.01; 205/118; 205/85 |
Current CPC
Class: |
C25D 17/10 20130101;
C25D 17/00 20130101; C25D 21/12 20130101 |
Class at
Publication: |
205/80 ; 205/118;
205/85; 204/242; 204/290.01 |
International
Class: |
C25D 005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 19, 2001 |
TW |
90125861 |
Claims
What is claimed is:
1. A method for controlling field flow decouple plating, comprising
following steps: a driving field for electrical swimming being
produced in plating solution; a pair of ionic positive pole and
extraction negative pole being connected to a plating power source
placed in the plating solution; positive metal ions on the ionic
positive pole being controlled by the driving field for electrical
swimming to move towards the extraction negative pole and the
electric extraction taking place at a recess on the extraction
negative pole surface.
2. The method for controlling field flow decouple plating according
to claim 1, wherein the driving field for electrical swimming
comprises a field positive pole and a field negative pole that are
connected to a high voltage electric field power source and placed
away from each other in the plating solution as well.
3. The method for controlling field flow decouple plating according
to claim 1, wherein the ionic positive pole and the extraction
negative pole in between the electric poles of the driving field
for electrical swimming are connected to the corresponding positive
and negative field poles.
4. An apparatus of field flow decouple plating, comprising: a high
voltage direct current power source for a driving field with
electrical swimming, providing a first positive pole and a first
negative pole; a low voltage plating direct current power source,
providing a second positive pole and a second negative pole;
plating solution, containing a driving positive pole and a driving
negative pole for electrical swimming and the driving positive pole
spacing apart from the driving negative pole, a driving positive
pole and a driving negative pole for electric swimming, and a metal
ionic positive pole and an extraction negative pole; wherein, the
first positive and first negative poles are connected to the
driving positive pole and the driving negative pole respectively,
the second positive pole is connected to the metal ionic positive
pole and the second negative pole to the extraction negative pole,
and the metal ionic positive pole and the extraction negative pole
are disposed to oppose to the driving positive pole and the driving
negative pole for electrical swimming respectively.
5. The apparatus of field flow decouple plating according to claim
4, wherein the first positive pole and the first negative pole are
covered with insulation material.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a method for controlling
field flow decouple plating, and, in particular, to a method of
controlling a decouple plating with which an electric field
allowing metal ions electrically swimming and current extracting
the metal ions can be controlled such that a coarse surface ready
for being plated can be controlled to acquire an even plating. The
present invention further relates to a novel plating apparatus
utilizing the control method so as to enhance the quality of
plating greatly.
[0003] 2. Description of Related Art
[0004] The basic theory with regard to metal plating includes a
process of electrical separation process, in which metal ions
moving away the surface of the positive pole and entering the
plating solution as positive ions; a process of electrical
swimming, in which the positive ions moving toward the negative in
the plating solution; and a process of electrical extraction, in
which the positive ions capture electrons from the negative pole as
metal molecules adhering to the negative poles.
[0005] Referring to FIG. 1, the earliest conventional plating
apparatus includes a rated voltage direct current power source 101,
a conductive work piece 102 connecting with a negative pole and a
plating metal 103 connecting with a positive pole. As soon as the
power is on, metal molecules 105 of the plating metal 103 loses
electrons and are ionized as positive metal ions 106 such that the
positive metal ions move toward the work piece 102 at the negative
pole to contact and obtain the electrons so as to analyze metal
molecules 104 electrically and deposit on the work piece 102 due to
diffusion action of ions and the electric field in the plating
solution. On the other hand, the electrolyzing reaction performs
continuously so that further new metal molecules 105 lose electrons
to become new metal positive ions 106 to replenish the consistency
of the plating solution. The positive metal ions 106 ceaselessly
move toward the work piece 102 at the negative pole to
electrolyzing-extract metal molecules 104 to complete the plating
process for the work piece due to diffusion action and electric
swimming caused by the electric field.
[0006] The plated thickness on the work piece is varied depending
on the time duration of plating while the prior art of plating
device shown in FIG. 1 is operated. The work piece at the negative
pole has a surface with certain roughness to result in uneven
plated surface while ions binds together with electrons in the
electrolyzing-extraction process. Referring to FIG. 2, a micro view
of electrolyzing-extraction process is illustrated to show the ions
binding together with the electrons in case of the work piece 102
having a coarse surface. Because the electrons in the work piece
102 at the negative pole move faster than positive ions 106 in the
plating solution, the surface of the work piece 102 at the left
side thereof produces an ion void layer 107 after being plated a
period of time and the electrons will aggregate at the surface of
the work piece 102 for waiting the positive ions electrically
swimming over the void layer 107. However, the surface of the work
piece 102 has a coarse extrusion 109 accumulating with more
electrons 110 under actuation of the electric field. A void layer
111 at the left side of the tip of the jut contacts with incoming
positive ions first so that the ions at the area of the tip has
faster and more extractions. Thus, a situation of uneven plating
surface occurs during the positive ions joining the electrons for
performing the process of electrolyzing extraction such that the
roughness of the plated surface is getting rougher and the
thickness of plating is getting more uneven.
[0007] Up to now, there are two ways having been proposed to
improve the plating process in order to attain homogeneous plated
thickness and a flat plated surface. One of the ways, which is
disclosed in U.S. Pat. No. 4,789,437, is that flattering agent such
as syrup is added in the plating solution. Referring to FIG. 3, the
flattering agent 205 is utilized to enclose the positive ions and
the positive ions enclosed by the flattering agent excludes
mutually to distribute uniformly with an equal span 202
respectively before reaching the work piece 102 at the negative
pole such that the ions 201 electrically swim toward the surface of
the work piece 102 in parallel and perpendicularly to the surface.
Being affected by the traction force of more electrons at the tip
part during moving close to work piece, each positive ion becomes
deviated and moves toward tip part with the flattering agent 205
enclosing each of the positive ions respectively. Because the
flattering agent 205 stays at the surface of the work piece after
the ions being electrically extracted, the tip part will be stayed
with more flattering agent 205 due to more electrically extracted
ions being produced at the tip part. Usually, the viscosity of the
flattering agent is greater than the plating solution and the
positive ions move slower in the flattering agent than in the
plating solution so that it is easier for the positive ions to
arrive the recess parts on the surface of the work piece instead of
the tip part thereof. The viscosity and distribution of the
flattering agent make the ions not easy to congregate at the tip
part where the electrons congregate and force the electrically
extracted ions to distribute on the surface of the work piece
evenly in order to obtain the purpose of flattering. However, the
first treatment with flattering agent is disadvantageous that it is
easy for the flattering agent to be surrounded and mixed in the
extracted metal molecules 207. Although it is possible to force the
flattering agent out by way of heat treatment, residue stress will
be produced at the plated surface. In addition, the plating
solution becomes more complicated and hard to be treated well in
case of being added with the flattering agent so that the cost for
the waste solution becomes higher.
[0008] The second way for improving the plating process in order to
attain homogeneous plated thickness and a flat plated surface is
pulse input power method, which has been disclosed in prior art
such as U.S. Pat. Nos. 4,459,460, 3,886,053, 6,071,398, 4,789,437
and 6,132,584. The basic theory of operation for the pulse input
method is shown in FIGS. 4 to 9.
[0009] Referring to FIG. 4, a state of the pulse input power being
not supplied is illustrated. Metal positive ions 301 should be
distributed evenly on the surface 305 of the work piece 102 at the
negative pole under an equilibrium condition due to the phenomenon
of exclusion between positive electricity of ions. Referring to
FIG. 5, it illustrates a state of electron current flows into the
work piece 102 at the negative pole simultaneously as soon as the
pulse source is input. Because electrons in the work piece flow
speedily and the heavier positive ions move slowly. The positive
ions can find out a nearest negative pole surface 305 respectively
to take an electron for being extracted as a metal molecule 303.
Referring to 6, the plating solution on the surface of the work
piece at the negative pole can form a void layer 305 of positive
ions while the metal ions on the metal surface have consumed
completely. Under this circumference, new electrons entering the
negative pole are unable to join with the positive ions except
aggregating at the surface of the work piece waiting for positive
ions electrically swimming from the void layer 304. Most electrons
may aggregate at the tip part 306 on the surface of the work piece
due to attraction of the positive pole. Because the tip part at the
surface thereof has a thinner void layer 307 and the electrons
aggregating at the tip part can produce a local electrical field
concentration 308 to attract the positive ions, the plating job
after the void layer 304 forming will concentrate at the tip part
to coarsen the plating surface with inconsistent thickness.
Referring to FIG. 7, a state of the pulse power source being off
supplying electrons right after the void layer forming for avoiding
the electrons concentrating at the tip part awaiting positive ions
is illustrated. The positive ions can be diffused to distribute
evenly so as to reach a balance naturally during the power being
disconnected. Then, next pulse plating can be treated after the
balance distribution. It is hard to estimate the number of the ions
on the surface of the work piece accurately during the pulse
plating. If less ions are estimated, it results in slow plating and
if excessive ions are estimated, it results in the electrons
aggregating at the tip part. The conventional way is to estimate
the ions excessively to admit more electrons and the excessive
electrons are removed by way of inverse impulse. FIG. 8 shows a
pulse wave signal is added with an inverse pulse. The pulse plating
can obtain a plating surface flatter than that obtained by way of
rated voltage. But, the ions diffusing to the surface of the work
piece naturally is limit in speed so that the plating is slow in
speed too. Further, it only can maintain the original flatness
instead of more flat plating surface even if the plating process is
the best condition, i.e., the ions are distributed evenly. In
addition, a further disadvantage is that it needs time to switch on
or off the pulse power source instead of switching on or off
instantaneously. An actual wave pattern for switching on or off the
power source is shown in FIG. 9 and a section of voltage rise 310
is increasing gradually with insufficient plating current. Under
the condition of insufficient plating current, the electrons will
choose a position with shortest electrical swimming distance to
extract the positive ions such that it is possible to produce tip
part effect. This is why the flattering agent is still utilized
while the method of pulse power input is applied.
[0010] Therefore, the electrons are influenced by the electric
field in case of the preceding conventional methods being used for
the plating operation so that the tip part jutting out of the
surface of the work piece at the negative pole aggregates more
electrons to result in the surface of the work piece being hard to
become flat completely with projection areas thereon getting more
extending outward and recess area thereon getting more dented.
SUMMARY OF THE INVENTION
[0011] Accordingly, an object of the present invention is to
provide a novel plating method, wherein the electric field and
flowing current can be adjusted independently so that the positive
ions will accumulate on the surface of the negative pole much
faster than the incoming electrons. Under the influence of the
electric field, positive ions will accumulate at the region closest
to the field negative pole, where they will wait at the recess of
the plating surface for electrons to arrive so electric extraction
can proceed and perform the uniform plating.
[0012] Another object of the present invention is to provide an
apparatus for performing the method for controlling field flow
decouple plating so that the uneven surface of the negative pole
will be flat after the plating.
[0013] Following the plating method of this invention, the
placement of its electric poles includes a high voltage power
source for the driving field for electrical swimming positive ions
but it does not provide the plating current. The electric poles
also include another low voltage high current power source for
supplying the plating current slow and it is located at the inner
of the poles of the high voltage power source. Therefore, by using
the connected high voltage power source to control the electrical
swimming speed of the positive ions to be faster than the electrons
supplied by the low voltage high current power source, more
positive ions will accumulate and await for incoming electrons so
that the spiking effect of the electrons will not have time to
occur. On the other hand, as the positive ions on the recess of the
extraction negative pole is closest to the high voltage power
source's negative pole which is positioned behind the extraction
negative pole, the ions will be attracted by the static electrons
of the high voltage power source and accumulate more rapidly in the
recess and perform electric extraction with the electrons. Thus,
the invention makes use of the fact that electric extraction is
more preferable in the recess of the extraction negative pole
compared to other regions; the uneven surface of the work piece at
the negative pole will become flat naturally by the plating method
of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The present invention can be more fully understood by
reference to the following detailed description and accompanying
drawings, in which:
[0015] FIG. 1 is a schematic diagram of a conventional apparatus
for plating illustrating an arrangement of battery power source and
two electric poles;
[0016] FIG. 2 is an enlarged schematic diagram illustrating the
surface roughness of the negative pole shown in FIG. 1 and a
reaction structure of positive ions electrically separating the
rough surface;
[0017] FIG. 3 is a schematic diagram illustrating a state with
regard to electric separating reaction of positive ion on the
surface of the negative pole after the plating solution in the
conventional plating apparatus being added with flatten agent;
[0018] FIGS. 4 to 9 are schematic diagrams illustrating a series
states of reactions with regard to positive ions of an electric
board being treated with conventional plating process under a
condition of pulse power source;
[0019] FIG. 10 is a plan view of a layout with regard to a field
power, an electric separation power source and all electric poles
according to the present invention; and
[0020] FIG. 11 is a schematic diagram illustrating positive ions
being electrically extracted between the field negative pole and
the extraction negative pole shown in FIG. 10.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0021] Referring to FIG. 10, the present invention includes two
sets of electric power sources 401, 405 in the plating device
constituted by the driving field of electrical swimming and plating
current. The field power source 401 is a field source for producing
the electrical swimming metal positive ions. The positive of the
field power source 401 is connected to the positive 402 of the
driving field for electrical swimming, while its negative is
connected to the negative of the driving field 403. The two
electric poles 402, 403 are both covered with insulation material
404. The driving field for electrical swimming only provides the
electric field for guiding the electrical swimming positive ions
and does not provide the plating current. Therefore, by utilizing a
high voltage and low current power source and insulation material
404, it will cut off the electrons from entering and thus prevent
the surface of both positive and negative from being covered with
ions or electric extraction. The plating power source 405 is used
for producing the plating current. The positive pole thereof is
connected to the positive pole 406 of the electrical swimming metal
ions, which is located near the right surface of the field positive
pole 402. While the negative pole 403 of the plating power source
(405) is connected to the extraction negative pole 407 on the
surface close to the field negative pole 403. The plating power
source 405 is mainly for controlling the flow speed of the electron
current, thus a low voltage and high current power source is being
used.
[0022] According to the present invention, the respective pole of
the field power source and the plating power source are first
placed into the plating solution in a plating trough. When the
field power source 401 and plating power source 405 form a closed
circuit, an electrical swimming electric field is established
between the two electric poles 402, 403 of the field power source
and it is used to guide the electrical swimming metal positive ions
in the plating solution 408. The purpose of the plating power
source 405 is to produce plating current, which will cause the
positive metal ions at the extraction negative pole to gain
electrons and allow the electric extraction to perform the plating
process at the extraction negative pole 407.
[0023] Referring to FIG. 11, indicated in this invention, due to
the presence of the negative pole 403 of the driving field for
electrical swimming, the positive metal ions are affected by it to
create a flatness effect on the extraction negative pole 407 of the
plating power source 405 and thus leading to the electric
extraction on the extraction negative pole 407. In the present
invention, by using a high voltage electric field power source 401
to control the faster electrical swimming speed of the positive
ions and at the same time, using low voltage power source 405 to
control the electrical extraction rate, more metal positive ions
will accumulate on the surface of the extraction negative pole 407
as the electrical swimming speed is faster than the plating speed.
When the height (409) of the surface of the extraction negative
pole 407 is not uniform, positive ions will congregate towards the
recess 410 of the extraction negative pole 407 under the attraction
of the static electrons on the field negative pole 403, which is
located behind the extraction negative pole 407. This leads to the
positive ions tending to move closer to the field negative pole 403
and wait for new electron (411) to arrive on the extraction
negative pole 407, in order to carry out electric extraction. Due
to the plating solution volume of the invention on the extraction
negative pole 407 has more recess regions than projecting regions;
the final result of plating will tend to be uniform across the
surface and thus achieving the goal of a flat plating surface.
[0024] The main feature of the present invention is in that two
control factors, the driving field for electrical swimming and
supply of the plating current, can be independently regulated. The
number of poles can be four or it can be reduced to three in case
of the two positive poles being combined together. The design of
the circuit can also allow a single power source to generate
individually controlled current and electrical field by way of the
circuit control. It is noted that the driving field for electrical
swimming and the extraction power source in the preceding
description and in the following claims being explained separately
is for the purpose of being understood easily. Hence, it does not
have to provide two independent power sources and any change can be
possibly done as long as the goal of the positive ions residing in
the recess of the surface of the extraction negative pole and
awaiting for electronic join and extraction can reach.
[0025] While the invention has been described with reference to a
preferred embodiment thereof, it is to be understood that
modifications or variations may be easily made without departing
from the spirit of this invention, which is defined by the appended
claims.
* * * * *