U.S. patent application number 16/393948 was filed with the patent office on 2020-02-13 for high-speed electroplating method.
This patent application is currently assigned to YUAN ZE UNIVERSITY. The applicant listed for this patent is YUAN ZE UNIVERSITY. Invention is credited to Cheng En HO, Bau Chin HUANG, Yu Kun WU, Cheng Hsien YANG.
Application Number | 20200048786 16/393948 |
Document ID | / |
Family ID | 69405573 |
Filed Date | 2020-02-13 |
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United States Patent
Application |
20200048786 |
Kind Code |
A1 |
HO; Cheng En ; et
al. |
February 13, 2020 |
HIGH-SPEED ELECTROPLATING METHOD
Abstract
A high-speed electroplating method is provided. The high-speed
electroplating method includes the following steps: providing a
substrate containing a conductive layer on its surface; coating a
dry-film photoresist on the conductive layer of the substrate, and
patterning the dry-film photoresist; performing a pretreatment
process to clean the substrate; disposing the substrate in an
electroplating solution; turning on an ultrasonic oscillation
machine to vibrate the electroplating solution, and turning on a
jet flow device to agitate the electroplating solution, and
performing a pre-electroplating process with a plating current
density of 0.5 A/dm.sup.2 to 5 A/dm.sup.2, and then performing a
high-speed electroplating process with a plating current density of
6 A/dm.sup.2 to 100 A/dm.sup.2; depositing a conductive pillar on
areas without the dry-film photoresist; and removing the dry-film
photoresist being coated on the conductive layer of the substrate.
Thus, the high-speed electroplating method can achieve high-speed
electrodeposition with uniform microstructures.
Inventors: |
HO; Cheng En; (Taoyuan,
TW) ; HUANG; Bau Chin; (Taoyuan, TW) ; WU; Yu
Kun; (Taoyuan, TW) ; YANG; Cheng Hsien;
(Taoyuan, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
YUAN ZE UNIVERSITY |
Taoyuan |
|
TW |
|
|
Assignee: |
YUAN ZE UNIVERSITY
Taoyuan
TW
|
Family ID: |
69405573 |
Appl. No.: |
16/393948 |
Filed: |
April 24, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C25D 3/38 20130101; C25D
7/00 20130101; C25D 5/34 20130101; C25D 5/022 20130101; C25D 5/10
20130101; C25D 3/48 20130101; C25D 21/10 20130101; C25D 3/46
20130101; C25D 3/50 20130101; C25D 5/00 20130101; C25D 5/08
20130101; C25D 3/12 20130101 |
International
Class: |
C25D 5/08 20060101
C25D005/08; C25D 5/02 20060101 C25D005/02; C25D 21/10 20060101
C25D021/10; C25D 5/34 20060101 C25D005/34 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 9, 2018 |
TW |
107127821 |
Claims
1. A high-speed electroplating method, comprising: providing a
substrate containing a conductive layer on its surface; coating a
dry-film photoresist on the conductive layer of the substrate, and
patterning the dry-film photoresist; disposing the substrate in an
electroplating solution; turning on an ultrasonic oscillation
machine to vibrate the electroplating solution, and turning on a
jet flow device to agitate the electroplating solution, and
performing a pre-electroplating process with a plating current
density of 0.5 A/dm.sup.2 to 5 A/dm.sup.2, and then performing a
high-speed electroplating process with a plating current density of
6 A/dm.sup.2 to 100 A/dm.sup.2; depositing a conductive pillar on
areas without the dry-film photoresist; and removing the dry-film
photoresist being coated on the conductive layer of the
substrate.
2. The method according to claim 1, wherein ultrasonic oscillation
of the electroplating solution is controlled to a frequency of 5
kilohertz (KHz) to 100 KHz.
3. The method according to claim 1, wherein metallic ions in the
electroplating solution are selected from the group consisting of
silver ions, gold ions, nickel ions, cobalt ions, palladium ions,
and copper ions.
4. The method according to claim 1, wherein the step of removing
the dry-film photoresist being coated on the conductive layer of
the substrate, further comprises: using tetrahydrofuran (THF) or
sodium hydroxide (NaOH) to remove the dry-film photoresist being
coated on the conductive layer of the substrate.
5. A high-speed electroplating method, comprising: providing a
substrate; forming a blind-hole structure or a through-hole
structure on the substrate through laser drilling or mechanical
drilling; forming a conductive layer on a surface of the substrate
and a hole wall of the blind-hole structure or the through-hole
structure; performing a pretreatment process to clean the
substrate; disposing the substrate in an electroplating solution;
and turning on an ultrasonic oscillation machine to vibrate the
electroplating solution, and turning on a jet flow device to
agitate the electroplating solution, and performing a
pre-electroplating process with a plating current density of 0.5
A/dm.sup.2 to 5 A/dm.sup.2, and then performing a high-speed
electroplating process to fill the blind-hole structure or the
through-hole structure with a metal conductive material with a
plating current density of 6 A/dm.sup.2 to 100 A/dm.sup.2.
6. The method according to claim 5, wherein ultrasonic oscillation
of the electroplating solution is controlled to a frequency of 5
KHz to 100 KHz.
7. The method according to claim 5, wherein metallic ions in the
electroplating solution are selected from the group consisting of
silver ions, gold ions, nickel ions, cobalt ions, palladium ions,
and copper ions.
8. A high-speed electroplating method, comprising: providing a
component containing a gap between two adjacent metal parts;
performing a pretreatment process to clean the component; disposing
the component in an electroplating solution; and turning on an
ultrasonic oscillation machine to vibrate the electroplating
solution, and turning on a jet flow device to agitate the
electroplating solution, and performing a pre-electroplating
process with a plating current density of 0.5 A/dm.sup.2 to 5
A/dm.sup.2, and then performing a high-speed electroplating process
to fill the gap with a plating current density of 6 A/dm.sup.2 to
100 A/dm.sup.2 to metallize the gap.
9. The method according to claim 8, wherein ultrasonic oscillation
of the electroplating solution is controlled to a frequency of 5
KHz to 100 KHz.
10. The method according to claim 8, wherein metallic ions in the
electroplating solution are selected from the group consisting of
silver ions, gold ions, nickel ions, cobalt ions, palladium ions,
and copper ions.
Description
CROSS-REFERENCE STATEMENT
[0001] All related applications are incorporated by reference
[0002] The present application is based on, and claims priority
from, Taiwan Application Serial Number 107127821, filed Aug. 9,
2018, the disclosure of which is hereby incorporated by reference
herein in its entirety.
BACKGROUND
Technical Field
[0003] The invention relates to an electroplating method. In
particular, the invention pertains to a high-speed
electrodeposition enhanced by ultrasonic oscillation.
Related Art
[0004] With the trend of thinner, lighter, and more
multifunctional, the microelectronic products are urgently needed
to increase the device quantity through the stacking package
technique in recent years.
[0005] In the design of stacking packages, each wiring layer of
different packaging levels needs to be connected with each other to
achieve electrical conduction. To meet such requirements, some
manufacturing methods are provided, for example, depositing a
conductive pillar between two different wiring layers through the
electroplating method, and then soldering the conductive pillar
with other wiring layer.
[0006] Nowadays, a low plating current density (for example, 0.5
A/dm.sup.2 to 3 A/dm.sup.2) electroplating process was commonly
utilized in the printed circuit board (PCB) field, but there is
still a concern regarding the long electroplating time. To avoid
this time-consuming process, a high-speed electroplating method
through increasing the plating current density has been proposed.
Unfortunately, the traditional high-speed electroplating method
might result in non-uniform electrodeposition and microstructure,
such as grain size. Please refer to FIG. 1, which is a scanning
electron microscopy image showing the cross-sectional view of a
copper pillar deposited via high-speed electroplating. It may be
seen that there is a problem of non-uniform grain size existed in
the copper pillar deposited via high-speed electroplating.
Specifically, smaller copper grains might appear in the upper layer
of the copper electrodeposition formed by high-speed
electroplating, and the smaller grains indicate that there are more
grain boundaries enclosing impurities, so that the increase in the
number of grain boundaries means that more impurities are included
in the copper plating, thereby reducing the conductive
characteristic of the copper pillars.
[0007] In conclusion, the prior art has the problem of
microstructure inhomogeneity; therefore, it is necessary to propose
an improved technical solution to avoid the inhomogeneous copper
microstructure.
SUMMARY
[0008] In view of the foregoing, the invention provides a
high-speed electroplating method.
[0009] According to one embodiment, the present invention provides
a high-speed electroplating method, and the method includes the
following steps: providing a substrate containing a conductive
layer on its surface; coating a dry-film photoresist on the
conductive layer of the substrate, and patterning the dry-film
photoresist; performing a pretreatment process to clean the
substrate; disposing the substrate in an electroplating solution;
turning on an ultrasonic oscillation machine to vibrate the
electroplating solution, and turning on a jet flow device to
agitate the electroplating solution, and performing a
pre-electroplating process with a plating current density of 0.5
A/dm.sup.2 to 5 A/dm.sup.2, and then performing a high-speed
electroplating process with a plating current density of 6
A/dm.sup.2 to 100 A/dm.sup.2; depositing a conductive pillar on
areas without the dry-film photoresist; and removing the dry-film
photoresist being coated on the conductive layer of the
substrate.
[0010] According to another embodiment, the present invention
provides a high-speed electroplating method, and the method
includes the following steps: providing a substrate; forming a
blind-hole structure or a through-hole structure on the substrate
through laser drilling or mechanical drilling; forming a conductive
layer on a surface of the substrate and a hole wall of the
blind-hole structure or the through-hole structure; performing a
pretreatment process to clean the substrate; disposing the
substrate in an electroplating solution; and turning on an
ultrasonic oscillation machine to vibrate the electroplating
solution, and turning on a jet flow device to agitate the
electroplating solution, and performing a pre-electroplating
process with a plating current density of 0.5 A/dm.sup.2 to 5
A/dm.sup.2, and then performing a high-speed electroplating process
to fill the blind-hole structure or the through-hole structure with
a metal conductive material with a plating current density of 6
A/dm.sup.2 to 100 A/dm.sup.2.
[0011] According to the other embodiment, the present invention
provides a high-speed electroplating method, and the method
includes the following steps: providing a component containing a
gap between two adjacent metal parts; performing a pretreatment
process to clean the component; disposing the component in an
electroplating solution; and turning on an ultrasonic oscillation
machine to vibrate the electroplating solution, and turning on a
jet flow device to agitate the electroplating solution, and
performing a pre-electroplating process with a plating current
density of 0.5 A/dm.sup.2 to 5 A/dm.sup.2, and then performing a
high-speed electroplating process to fill the gap with a plating
current density of 6 A/dm.sup.2 to 100 A/dm.sup.2 to metallize the
gap.
[0012] As described above, and the difference between the
conventional technology and the present invention is that
performing high plating current density electroplating by disposing
a substrate or a component in an electroplating solution vibrated
by ultrasonic waves and agitated by a jet flow.
[0013] By aforementioned technology means, the present invention
may provide metal depositions with uniform microstructures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The invention will become more fully understood from the
detailed description given herein below illustration only, and thus
is not limitative of the present invention, and wherein:
[0015] FIG. 1 is a scanning electron microscopy image showing the
cross-sectional view of a copper pillar deposited via high-speed
electroplating;
[0016] FIG. 2 is a flowchart showing the steps for operating a
high-speed electroplating method, according to the first embodiment
of the present invention;
[0017] FIG. 3A is a schematic drawing of an embodiment of step 110
of FIG. 2;
[0018] FIG. 3B is a schematic drawing of an embodiment of step 120
of FIG. 2;
[0019] FIG. 3C is a schematic drawing of an embodiment of step 140
and step 150 of FIG. 2;
[0020] FIG. 3D is a schematic drawing of an embodiment of step 160
of FIG. 2;
[0021] FIG. 3E is a schematic drawing of an embodiment of step 170
of FIG. 2;
[0022] FIG. 4A is a top view schematic drawing of first embodiment
of FIG. 3B;
[0023] FIG. 4B is a top view schematic drawing of second embodiment
of FIG. 3B;
[0024] FIG. 5 is a flowchart showing steps for operating a
high-speed electroplating method, according to the second
embodiment of the present invention;
[0025] FIG. 6 is a schematic drawing of an embodiment of step 140
and step 350 of FIG. 5;
[0026] FIG. 7A is a scanning electron microscopy image showing the
cross-sectional view of an embodiment of a copper pillar deposited
via the high-speed electroplating method of FIG. 2;
[0027] FIG. 7B is a scanning electron microscopy image showing the
cross-sectional view of an embodiment of a copper pillar deposited
via the high-speed electroplating method of FIG. 5;
[0028] FIG. 8 is a flowchart showing steps for operating a
high-speed electroplating method according to the third embodiment
of the present invention;
[0029] FIG. 9A is a schematic drawing of an embodiment of a
blind-hole structure of step 420 of FIG. 8;
[0030] FIG. 9B is a schematic drawing of an embodiment of a
through-hole structure of step 420 of FIG. 8;
[0031] FIG. 10A is a schematic drawing of an embodiment of a
blind-hole filling via the blind-hole structure of step 460 of FIG.
8;
[0032] FIG. 10B is a schematic drawing of an embodiment of a
through-hole filling via the through-hole structure of step 460 of
FIG. 8;
[0033] FIG. 11 is a flowchart showing steps for operating a
high-speed electroplating method according to the fourth embodiment
of the present invention;
[0034] FIG. 12 is a flowchart showing steps for operating a
high-speed electroplating method according to the fifth embodiment
of the present invention;
[0035] FIG. 13A is a schematic drawing of an embodiment of a
component containing a gap between two adjacent metal parts of step
610 of FIG. 12;
[0036] FIG. 13B is a schematic drawing of an embodiment of
metallization of the gap of step 640 of FIG. 12; and
[0037] FIG. 14 is a flowchart showing steps for operating a
high-speed electroplating method according to the sixth embodiment
of the present invention.
DETAILED DESCRIPTION
[0038] The following embodiments of the present invention are
herein described in detail with reference to the accompanying
drawings. These drawings show specific examples of the embodiments
of the present invention. It is to be understood that these
embodiments are exemplary implementations and are not to be
construed as limiting the scope of the present invention in any
way. Further modifications to the disclosed embodiments, as well as
other embodiments, are also included within the scope of the
appended claims. These embodiments are provided so that this
disclosure is thorough and complete, and fully conveys the
inventive concept to those skilled in the art. Regarding the
drawings, the relative proportions and ratios of elements in the
drawings may be exaggerated or diminished in size for the sake of
clarity and convenience. Such arbitrary proportions are only
illustrative and not limiting in any way. The same reference
numbers are used in the drawings and description to refer to the
same or like parts.
[0039] As used herein, the term "or" includes any and all
combinations of one or more of the associated listed items.
[0040] Please refer to FIG. 2 and FIGS. 3A to 3E, wherein FIG. 2 is
a flowchart showing steps for operating a high-speed electroplating
method according to the first embodiment of the present invention,
and FIGS. 3A to 3E are schematic drawings of an embodiment of steps
110, 120, 140 and 150, 160, and 170 of the high-speed
electroplating method of FIG. 2. In this embodiment, the high-speed
electroplating method includes the following steps: providing a
substrate containing a conductive layer on its surface (step 110);
coating a dry-film photoresist on the conductive layer of the
substrate, and patterning the dry-film photoresist (step 120);
performing a pretreatment process to clean the substrate (step
130); disposing the substrate in an electroplating solution (step
140); turning on an ultrasonic oscillation machine to vibrate the
electroplating solution, and performing a pre-electroplating
process with a plating current density of 0.5 A/dm.sup.2 to 5
A/dm.sup.2, and then performing a high-speed electroplating process
with a plating current density of 6 A/dm.sup.2 to 100 A/dm.sup.2
(step 150); depositing a conductive pillar on areas without the
dry-film photoresist (step 160); and removing the dry-film
photoresist being coated on the conductive layer of the substrate
(step 170).
[0041] Please refer to FIG. 2 and FIG. 3A. In step 110, the
thickness D of the substrate 200 may be, but not limited to, 0.2 to
1 millimeter (mm), and the substrate 200 may be the bismaleimide
triazine (BT) substrate, the flame retardant 4 (FR4) substrate, the
copper substrate or the ajinomoto build-up films (ABF) substrate,
and the material of the substrate 200 may be, but not limited to,
selected from the group consisting of glass fiber, epoxy resin,
polyphenylene oxide (PPO), polyimide (PI), and polypropylene (PP).
In this embodiment, the substrate 200 may be, but not limited to, a
printed circuit board. There is a conductive layer 210 formed on
the double-sided surfaces of the substrate 200 respectively.
However, this embodiment is not intended to limit the present
invention, and may be adjusted according to actual requirements.
For example, there is a conductive layer 210 only formed on the
single-sided surface of the substrate 200. Since the substrate 200
is a non-conductor, it is required to perform an electroless
plating process, a physical vapor deposition (PVD) process or a
chemical vapor deposition (CVD) process on the surface thereof, so
that the surface of the substrate 200 has a conductive layer 210 to
facilitate subsequent electroplating. Electroplating is performed
on the conductive layer 210 to form a conductive pillar 50. The
material of the conductive layer 210 may be selected from the group
consisting of silver, gold, nickel, cobalt, palladium and copper,
and may be adjusted according to actual requirements.
[0042] Please refer to FIG. 2 and FIG. 3B. Since the conductive
pillars 50 are to be deposited on the conductive layer 210 of the
substrate 200 instead of being electroplated with a metal film on
the conductive layer 210, in step 120, the dry-film photoresist 60
may be uniformly attached to the conductive layer 210 through a
laminator. In this embodiment, the dry-film photoresist 60 may be a
negative dry-film photoresist, and then perform an exposure and
development process on the dry-film photoresist 60 by using a
correspondingly shaped mask (i.e., patterning the dry-film
photoresist 60) according to the user's requirement for the
appearance of the conductive pillars 50 (i.e., the shape of the
bottom surface of each conductive pillar 50) to make the exposed
dry-film photoresist 60 be polymerized and hardened, and make the
unexposed dry-film photoresist 60 be the original monomers and be
stripped by the developer, and then patterning the dry-film
photoresist 60 according to the shape of the mask and creating the
required appearance of the conductive pillar 50 (i.e., the shape of
the bottom surface of the conductive pillar 50), but this
embodiment is not intended to limit the invention. For example, the
dry-film photoresist 60 may be a positive dry-film photoresist.
When an exposure and development process is performed on the
dry-film photoresist 60, the exposed dry-film photoresist 60 is
decomposed and then may be stripped by the developer, and the
dry-film photoresist 60 is patterned according to the shape of the
mask and the required appearance of the conductive pillar 50 (i.e.,
the shape of the bottom surface of the conductive pillar 50) is
created.
[0043] In addition, since the height of the conductive pillar 50 is
less than or equal to the height Q of the dry-film photoresist 60
attached to the conductive layer 210, when the dry-film photoresist
60 is uniformly attached to the conductive layer 210 through the
laminator, it should be noted that the height Q of the dry-film
photoresist 60 uniformly attached to the conductive layer 210
conforms to the user's requirement of the conductive pillars 50
(that is, the height Q of the dry-film photoresist 60 uniformly
attached to the conductive layer 210 needs to be greater than or
equal to the height Q of the conductive pillar 50 on the conductive
layer 210 the user expects).
[0044] In this embodiment, the expected conductive pillars 50 may
be cylindrical pillars, so that the expected appearance of the
conductive pillars 50 (i.e., the shape of the bottom surface of the
conductive pillars 50) may be a circle (as shown in FIG. 4A, which
is a top view schematic drawing of first embodiment of FIG. 3B).
The diameter of the circle may be, but not limited to, 120
micrometers (.mu.m) to 10 millimeters (mm), but this embodiment is
not intended to limit the invention, and may be adjusted according
to actual requirements. For example, the expected conductive
pillars 50 may be a square pillar, so that the expected appearance
of the conductive pillars 50 (i.e., the shape of the bottom surface
of the conductive pillars 50) may be a square (as shown in FIG. 4B,
which is a top view schematic drawing of second embodiment of FIG.
3B), and the side length of the square may be, but not limited to,
120 .mu.m to 10 mm.
[0045] Please refer to FIG. 2, the pretreatment process described
in step 130 may include: sequentially cleaning the conductive layer
210 of the substrate 200 with water, a detergent and pickle liquor.
More specifically, the pretreatment process may clean the stains on
the conductive layer 210 and remove the oxide layer on the surface
thereof, and prevent bubbles from being left on the conductive
layer 210. Water may be, but not limited to, deionized water. It
should be noted that when the pickle liquor used for pickling and
cleaning does not contain metallic ions of the electroplating
solution, the conductive layer 210 of the substrate 200 may be
washed again with water to avoid affecting the quality of the
subsequent electroplating metal, and then the procedure of the
subsequent steps 140 to 170 is performed.
[0046] Next, please refer to FIG. 2, FIG. 3C and FIG. 3D. After
performing the exposure development process (i.e., step 120) and
the pretreatment process (i.e., step 130), the substrate 200 having
the conductive layer 210 and the patterned dry-film photoresist 60
is disposed in the electroplating solution 30 (i.e., step 140), and
the ultrasonic oscillating device 10 is turned on to vibrate the
electroplating solution 30 and the power supply device 20 is used
to perform the pre-electroplating process with the plating current
density of 0.5 A/dm.sup.2 to 5 A/dm.sup.2, and then perform the
high-speed electroplating process with the plating current density
of 6 A/dm.sup.2 to 100 A/dm.sup.2 (i.e., step 150), that is,
performing the high-speed electroplating with ultrasonic waves,
thereby depositing the conductive pillars 50 on areas where the
conductive layer 210 is not coated with the dry-film photoresist 60
(i.e., step 160). When step 140 is performed, the substrate 200
having the conductive layer 210 and the patterned dry-film
photoresist 60 is disposed at the position of the cathode, and the
position of the anode may be configured with a soluble anode, which
is used to supplement the consumption of metallic ions of the
electroplating solution, or an insoluble anode, such as a titanium
net and an iridium/tantalum oxide composite anode. In the
embodiment, the anode may be, but not limited to, an
iridium/tantalum oxide composite insoluble anode. In addition,
since double-sided electroplating is to be performed in the
embodiment, the position of the substrate 200 containing the
conductive layer 210 and the patterned dry-film photoresist 60 may
be located at the center of the electroplating bath, and two anodes
are disposed at the both sides of the electroplating bath. In the
embodiment, the metallic ions in the electroplating solution 30 may
be selected from the group consisting of silver ions, gold ions,
nickel ions, cobalt ions, palladium ions and copper ions, and may
be adjusted according to the material of the conductive pillars 50
that is expected to be deposited. During the high-speed
electroplating process with ultrasonic waves (i.e., step 150), the
power supply device 20 may be used to perform the
pre-electroplating process with the plating current density of 0.5
A/dm.sup.2 to 5 A/dm.sup.2, and then increase the plating current
density (i.e., the plating current density is 6 A/dm.sup.2 to 100
A/dm.sup.2) to perform the high-speed electroplating to reduce the
required time for electroplating.
[0047] According to Faraday's law,
.delta. = M .times. .eta. z .times. F .times. .rho. .times. j
.times. t , ##EQU00001##
wherein .delta. is the height of the conductive pillar 50 (unit:
.mu.m), j is the plating current density (unit: A/dm.sup.2), t is
the electroplating time (unit: minute), .eta. is the current
efficiency, M is the molecular weight (unit: g/mol), z is the
valence of the metal (i.e., the number of electrons transferred in
each metallic ion), F is the Faraday constant (i.e., 96485 C/mol),
and .rho. is the density of the electrolyte, it is known that the
required time for electroplating may be derived from the plating
current density and the height of the conductive pillar 50 that is
expected to be deposited via electroplating. In the embodiment, it
is expected that the height of the conductive pillars 50 deposited
via electroplating may be 130 .mu.m to 500 .mu.m. For example, when
it is expected that the conductive pillars 50 deposited via
electroplating may be copper pillars, and the height of the
conductive pillars 50 may be 168 .mu.m, Faraday's law shows that
the corresponding formula is .delta.=0.22.times.j.times.t, so it
may be pre-electroplated for approximately 15 minutes with the
plating current density of 3 A/dm.sup.2 to deposit 10 .mu.m copper
pillars, and then electroplated for approximately 9 minutes with
the plating current density of 5 A/dm.sup.2 to deposit 10 .mu.m
copper pillars (at this time, the height of each copper pillar is
20 .mu.m), and then electroplated for approximately 56 minutes with
the plating current density of 12 A/dm.sup.2 to deposit 148 .mu.m
copper pillars (at this time, the height of each copper pillar is
168 .mu.m).
[0048] In addition, in the embodiment, the ultrasonic oscillation
of the electroplating solution is controlled to a frequency of 5
kilohertz (KHz) to 100 KHz, and the electroplating solution 30 may
contain, in addition to copper ions, a solvent (e.g., water and
sulfuric acid) and additives (e.g., brightener, carrier, leveler,
wetting agent, and chloride ions).
[0049] Next, please refer to FIG. 2 and FIG. 3E. After the
conductive pillars 50 with the expected height is obtained
according to the plating current density and the corresponding
electroplating time, tetrahydrofuran (THF) or sodium hydroxide
(NaOH) may be used to strip the patterned dry-film photoresist 60
be coating on the conductive layer 210 to reveal the conductive
pillars 50 deposited via electroplating.
[0050] In addition, the electroplating layer would be deposited in
a slower rate when the temperature of the electroplating solution
30 is lower than 25.degree. C., and the additive is unstable when
the temperature of the electroplating solution 30 is higher than
30.degree. C. Thus, in this embodiment, the high-speed
electroplating method may further include the step of controlling
the temperature of the electroplating solution to be 25.degree. C.
to 30.degree. C. through a temperature control device (not
drawn).
[0051] Please refer to FIG. 5, which is a flowchart showing steps
for operating a high-speed electroplating method according to the
second embodiment of the present invention, the high-speed
electroplating method includes the following steps: providing a
substrate containing a conductive layer on its surface (step 110);
coating a dry-film photoresist on the conductive layer of the
substrate, and patterning the dry-film photoresist (step 120);
performing a pretreatment process to clean the substrate (step
130); disposing the substrate in an electroplating solution (step
140); turning on an ultrasonic oscillation machine to vibrate the
electroplating solution, and turning on a jet flow device to
agitate the electroplating solution, and performing a
pre-electroplating process with a plating current density of 0.5
A/dm.sup.2 to 5 A/dm.sup.2, and then performing a high-speed
electroplating process with a plating current density of 6
A/dm.sup.2 to 100 A/dm.sup.2 (step 350); depositing a conductive
pillar on areas without the dry-film photoresist (step 160); and
removing the dry-film photoresist being coated on the conductive
layer of the substrate (step 170).
[0052] In other words, the difference between this embodiment and
the first embodiment is that the high-speed electroplating method
of this embodiment may further include the step of: turning on the
jet flow device 40 to agitate the electroplating solution 30 (as
shown in FIG. 6, which is a schematic drawing of an embodiment of
step 140 and step 350 of FIG. 5) to improve the fluidity of the
electroplating solution 30 and enhance mixing effect. The jet flow
rate of the jet flow device 40 may be, but not limited to, less
than or equal to 10 liters per minute.
[0053] Please refer to FIG. 7A and FIG. 7B, wherein FIG. 7A is a
scanning electron microscopy image showing the cross-sectional view
of an embodiment of a copper pillar deposited via the high-speed
electroplating method of FIG. 2, and FIG. 7B is a scanning electron
microscopy image showing the cross-sectional view of an embodiment
of a copper pillar deposited via the high-speed electroplating
method of FIG. 5.
[0054] In FIG. 7A, it may be known that the copper pillar deposited
via the high-speed electroplating method of FIG. 2 has relatively
uniform grain sizes, which solves the problem that the copper
pillar deposited via the conventional high-speed electroplating has
non-uniform grain sizes and solves the problem of smaller grains in
the upper region. Due to the cavitation of the ultrasonic waves,
the electroplating solution may be more fully entered into the hole
(that is, the groove formed by the conductive layer and the
patterned dry-film photoresist), and the copper ions and additives
may be immediately replenished to enhance the mass transfer in the
hole. Thus, the copper pillar deposited via the high-speed
electroplating method of FIG. 2 has relatively uniform grain sizes.
In FIG. 7B, it may be known that the copper pillar deposited via
the high-speed electroplating method of FIG. 5 not only has
relatively uniform grain sizes but also has no necking which the
copper pillar deposited via the high-speed electroplating method of
FIG. 2 has, thereby improving the mechanical properties of the
overall copper pillar.
[0055] In addition, a series of indentation tests is performed on
the copper pillar deposited via the high-speed electroplating
method of FIG. 5 (as shown in FIG. 7B) and the copper pillar of
FIG. 1 deposited via the conventional high-speed electroplating by
a nanoindenter. The hardness of the copper pillar deposited via the
high-speed electroplating method of FIG. 5 may be approximately 2.0
GPa to 2.2 GPa, the Young's modulus of the copper pillar deposited
via the high-speed electroplating method of FIG. 5 may be
approximately 98.9 GPa to 105.6 GPa, and the stiffness of the
copper pillar deposited via the high-speed electroplating method of
FIG. 5 may be approximately 2.48.times.10.sup.5 N/m to
2.61.times.10.sup.5 N/m. However, the hardness of the copper pillar
deposited via conventional high-speed electroplating may be
approximately 1.6 GPa to 1.7 GPa, the Young's modulus of the copper
pillar deposited via conventional high-speed electroplating may be
approximately 91.8 GPa to 104.6 GPa, and the stiffness of the
copper pillar deposited via conventional high-speed electroplating
may be approximately 2.16.times.10.sup.5 N/m to 2.57.times.10.sup.5
N/m. Therefore, it is known that the mechanical properties of the
copper pillar deposited via the high-speed plating method of FIG. 5
are higher than those of copper pillar deposited via conventional
high-speed electroplating.
[0056] The high-speed electroplating method of the present
invention may be used to form the above-mentioned conductive
pillars, and further used to fill the blind-hole structure or the
through-hole structure. For details, please refer to FIG. 8 to FIG.
10B, wherein FIG. 8 is a flowchart showing steps for operating a
high-speed electroplating method according to the third embodiment
of the present invention, FIG. 9A is a schematic drawing of an
embodiment of a blind-hole structure of step 420 of FIG. 8, FIG. 9B
is a schematic drawing of an embodiment of a through-hole structure
of step 420 of FIG. 8, FIG. 10A is a schematic drawing of an
embodiment of a blind-hole filling via the blind-hole structure of
step 460 of FIG. 8, and FIG. 10B is a schematic drawing of an
embodiment of a through-hole filling via the through-hole structure
of step 460 of FIG. 8. In the embodiment, the high-speed
electroplating method includes the following steps: providing a
substrate (step 410); forming a blind-hole structure or a
through-hole structure on the substrate through laser drilling or
mechanical drilling (step 420); forming a conductive layer on a
surface of the substrate and a hole wall of the blind-hole
structure or the through-hole structure (step 430); performing a
pretreatment process to clean the substrate (step 440); disposing
the substrate in an electroplating solution (step 450); and turning
on an ultrasonic oscillation machine to vibrate the electroplating
solution, and performing a pre-electroplating process with a
plating current density of 0.5 A/dm.sup.2 to 5 A/dm.sup.2, and then
performing a high-speed electroplating process to fill the
blind-hole structure or the through-hole structure with a metal
conductive material with a plating current density of 6 A/dm.sup.2
to 100 A/dm.sup.2 (step 460).
[0057] In step 410, the thickness D of the substrate 300 may be,
but not limited to, 0.2 mm to 3 mm, and the substrate 300 may be
the BT substrate, the FR4 substrate, the copper substrate or the
ABF substrate, and the material of the substrate 300 may be, but
not limited to, selected from the group consisting of glass fiber,
epoxy resin, PPO, PI, and PP. In this embodiment, the substrate 300
may be, but not limited to, a printed circuit board.
[0058] In step 420, the blind-hole structures 70 (as shown in FIG.
9A) or the through-hole structures 80 (such as FIG. 9B) are formed
on the substrate 300 through a laser drilling process or a
mechanical drilling process. The number and location of the
blind-hole structures 70 or the through-hole structures 80 may be
adjusted according to actual requirements. When the blind-hole
structure 70 is a circular blind hole (that is, its top view is a
circle), the diameter of the circle may be 50 .mu.m to 200 .mu.m,
and the AR value (i.e., the aspect ratio, the ratio of the
thickness of the substrate 300 to the diameter of the circle) may
be 0.5 to 4.0. When the through-hole structure 80 is a circular
through hole (that is, its top view is a circle), the diameter of
the circle may be 50 .mu.m to 200 .mu.m, and the AR value may be
1.0 to 20. In addition, the substrate 300 may have a bottom copper
layer 72 for conducting the blind-hole structures 70 respectively,
and the bottom copper layer 72 may be formed by a lamination
process or an electroless plating process.
[0059] In step 430, since the substrate 300 is a non-conductor, it
is required to perform an electroless plating process, a physical
vapor deposition (PVD) process or a chemical vapor deposition (CVD)
process to make the surface of the substrate 300 and the hole wall
of the blind-hole structures 70 or the through-hole structures 80
with the conductive layer 85 to facilitate subsequent
electroplating for blind-hole/through-hole fillings. The material
of the conductive layer 85 may be selected from the group
consisting of silver, gold, nickel, cobalt, palladium and copper.
The thickness of the conductive layer 85 may be, but not limited
to, 1 .mu.m.
[0060] In step 440, the pretreatment process may include:
sequentially cleaning the surface of the substrate 300 and the hole
wall of the blind-hole structures 70 or the hole wall of the
through-hole structures 80 with water, a detergent and pickle
liquor. More specifically, the pretreatment process may clean the
stains on the conductive layer 85 and remove the oxide layer on the
surface thereof, and prevent bubbles from being left on the
conductive layer 85. Water may be, but not limited to, deionized
water. It should be noted that when the pickle liquor used for
pickling and cleaning does not contain metallic ions of the
electroplating solution, the conductive layer 85 of the substrate
300 may be washed again with water to avoid affecting the quality
of the subsequent electroplating metal, and then the procedure of
the subsequent steps 450 to 460 is performed.
[0061] After step 410 to step 440 are performed, the substrate 300
is disposed in the electroplating solution (i.e., step 450), and
the ultrasonic oscillating device is turned on to vibrate the
electroplating solution, and the power supply device is used to
perform the pre-electroplating process with the plating current
density of 0.5 A/dm.sup.2 to 5 A/dm.sup.2, and then perform the
high-speed electroplating process to fill the blind-hole structures
70 or the through-hole structures 80 with a conductive material
with the plating current density of 6 A/dm.sup.2 to 100 A/dm.sup.2
(i.e., step 460). When step 450 is performed, the substrate 300 is
disposed at the position of the cathode, and the position of the
anode may be configured with a soluble anode, which is used to
supplement the consumption of metallic ions of the electroplating
solution, or an insoluble anode, such as a titanium net and an
iridium/tantalum oxide composite anode. In the embodiment, the
anode may be, but not limited to, an iridium/tantalum oxide
composite insoluble anode, the metallic ions in the electroplating
solution 30 may be selected from the group consisting of silver
ions, gold ions, nickel ions, cobalt ions, palladium ions and
copper ions, and may be adjusted according to the material of the
blind-holes/through-holes that are expected to be deposited. During
the high-speed electroplating process with ultrasonic waves (i.e.,
step 460), the power supply device may be used to perform the
pre-electroplating process with the plating current density of 0.5
A/dm.sup.2 to 5 A/dm.sup.2, and then increase the plating current
density (i.e., the plating current density is 6 A/dm.sup.2 to 100
A/dm.sup.2) to perform the high-speed electroplating, wherein the
times for the pre-electroplating process and perform the high-speed
electroplating may be adjusted by actual requirements.
[0062] Due to the cavitation effect of the ultrasonic waves, the
electroplating solution may be more fully entered into the
blind-hole structure 70 or the through-hole structure 80, and the
metallic ions and additives are immediately replenished, so that
the blind-hole structure 70 or the through-hole structure 80 is
filled with metal conductive material corresponding to the metallic
ions, thereby depositing the blind-hole 75 (as shown in FIG. 10A)
or the through-hole 82 (as shown in FIG. 10B), and avoiding
appearance and structural defects (e.g., void formation and
non-uniform grain distribution).
[0063] In addition, please refer to FIG. 11, which is a flowchart
showing steps for operating a high-speed electroplating method
according to the fourth embodiment of the present invention. The
high-speed electroplating method may include the following steps:
providing a substrate (step 410); forming a blind-hole structure or
a through-hole structure on the substrate through laser drilling or
mechanical drilling (step 420); forming a conductive layer on a
surface of the substrate and a hole wall of the blind-hole
structure or the through-hole structure (step 430); performing a
pretreatment process to clean the substrate (step 440); disposing
the substrate in an electroplating solution (step 450); and turning
on an ultrasonic oscillation machine to vibrate the electroplating
solution, and turning on a jet flow device to agitate the
electroplating solution, and performing a pre-electroplating
process with a plating current density of 0.5 A/dm.sup.2 to 5
A/dm.sup.2, and then performing a high-speed electroplating process
to fill the blind-hole structure or the through-hole structure with
a metal conductive material with a plating current density of 6
A/dm.sup.2 to 100 A/dm.sup.2 (step 560).
[0064] In other words, the difference between this embodiment and
the third embodiment is that the high-speed electroplating method
of this embodiment may further include the step of: turning on the
jet flow device to agitate the electroplating solution to improve
the fluidity of the electroplating solution and enhance mixing
effect. The jet flow rate of the jet flow device may be, but not
limited to, less than or equal to 10 liters per minute.
[0065] The high-speed electroplating method of the present
invention may be used to deposit the above-mentioned conductive
pillars and blind-holes/through-holes, and further used to
metallize a gap (which may be applied to the three-dimensional (3D)
integrated circuit (IC) packaging technology or the 3D electronic
assembly). The technology of metallization of the gap may be used
to directly remove the solder, and solve the damage problem caused
by solder shrinkage or aging, and also avoid the formation of the
brittle intermetallic compound joint (IMC joint) and the formation
of microvoids in the micro joint. For details, please refer to
FIGS. 12 to 13B, wherein FIG. 12 is a flowchart showing steps for
operating a high-speed electroplating method according to the fifth
embodiment of the present invention, FIG. 13A is a schematic
drawing of an embodiment of a component containing a gap between
two adjacent metal parts of step 610 of FIG. 12, and FIG. 13B is a
schematic drawing of an embodiment of metallization of the gap of
step 640 of FIG. 12. In this embodiment, the high speed
electroplating method includes the following steps: providing a
component containing a gap between two adjacent metal parts (step
610); performing a pretreatment process to clean the component
(step 620); disposing the component in an electroplating solution
(step 630); and turning on an ultrasonic oscillation machine to
vibrate the electroplating solution, and performing a
pre-electroplating process with a plating current density of 0.5
A/dm.sup.2 to 5 A/dm.sup.2, and then performing a high-speed
electroplating process to fill the gap with a plating current
density of 6 A/dm.sup.2 to 100 A/dm.sup.2 to metallize the gap
(step 640).
[0066] In step 610, the component 400 has two or more metal parts
76, and the gap 90 is between two adjacent metal parts 76. The
spacing of the gap 90 maybe, but not limited to, 10 .mu.m to 100
.mu.m. The material of the metal parts 76 may be selected from the
group consisting of silver, gold, nickel, cobalt, palladium and
copper, and the shape of the metal parts 76 may be circular or
square. When the metal parts 76 are round metal parts (i.e., the
top view is circular), the diameter may be 10 .mu.m to 200 .mu.m;
when the metal parts 76 are square metal parts (that is, the top
view thereof is square), the length and/or width may be 10 .mu.m to
200 .mu.m.
[0067] In step 620, the pretreatment process may include the step
of: sequentially cleaning the component 400 with water, a detergent
and pickle liquor. More specifically, the pretreatment process may
clean the stains on the gap 90, remove the oxide layer on the
surface thereof, and prevent bubbles from being left on the gap 90.
Water may be, but not limited to, deionized water. It should be
noted that, when the pickle liquor used for pickling and cleaning
does not contain metallic ions of the electroplating solution, the
gap 90 may be washed again with water to avoid affecting the
quality of the subsequent electroplating metal, and then the
procedure of the subsequent steps 630 to 640 is performed.
[0068] After step 610 to step 620 are performed, the component 400
is disposed in the electroplating solution (i.e., step 630), and
the ultrasonic oscillating device is turned on to vibrate the
electroplating solution, and the power supply device is used to
perform the pre-electroplating process with the plating current
density of 0.5 A/dm.sup.2 to 5 A/dm.sup.2, and then perform the
high-speed electroplating process to fill the gap 90 with the
plating current density of 6 A/dm.sup.2 to 100 A/dm.sup.2 to
metallize the gap 90 (i.e., step 640). When step 630 is performed,
the component 400 is disposed at the position of the cathode, and
the position of the anode may be configured with a soluble anode,
which is used to supplement the consumption of metallic ions of the
electroplating solution, or an insoluble anode, such as a titanium
net and an iridium/tantalum oxide composite anode. In the
embodiment, the anode may be, but not limited to, an
iridium/tantalum oxide composite insoluble anode, the metallic ions
in the electroplating solution 30 may be selected from the group
consisting of silver ions, gold ions, nickel ions, cobalt ions,
palladium ions and copper ions, and may be adjusted according to
actual requirements. During the high-speed electroplating process
with ultrasonic waves (i.e., step 640), the power supply device may
be used to perform the pre-electroplating process with the plating
current density of 0.5 A/dm.sup.2 to 5 A/dm.sup.2, and then
increase the plating current density (i.e., the plating current
density is 6 A/dm.sup.2 to 100 A/dm.sup.2) to perform the
high-speed electroplating, wherein the times for the
pre-electroplating process and perform the high-speed
electroplating may be adjusted by actual requirements.
[0069] Due to the cavitation effect of the ultrasonic waves, the
electroplating solution may be more fully entered into the gap 90,
and the metallic ions and additives are instantly replenished, so
that the gap 90 is filled with metal conductive material
corresponding to the metallic ions, thereby metallizing the gap 90
(as shown in FIG. 13B), and avoiding appearance and structural
defects (e.g., void formation and non-uniform grain
distribution).
[0070] In addition, please refer to FIG. 14, which is a flowchart
showing steps for operating a high-speed electroplating method
according to the sixth embodiment of the present invention. The
high-speed electroplating method may include the following steps:
providing a component containing a gap between two adjacent metal
parts (step 610); performing a pretreatment process to clean the
component (step 620); disposing the component in an electroplating
solution (step 630); and turning on an ultrasonic oscillating
device to vibrate the electroplating solution, and turning on a jet
flow device to agitate the electroplating solution, and performing
a pre-electroplating process with a plating current density of 0.5
A/dm.sup.2 to 5 A/dm.sup.2, and then performing a high-speed
electroplating process to fill the gap with a plating current
density of 6 A/dm.sup.2 to 100 A/dm.sup.2 to metallize the gap
(step 740).
[0071] In other words, the difference between this embodiment and
the fifth embodiment is that the high-speed electroplating method
of this embodiment may further include the step of: turning on the
jet flow device to agitate the electroplating solution to improve
the fluidity of the electroplating solution and enhance mixing
effect. The jet flow rate of the jet flow device may be, but not
limited to, less than or equal to 10 liters per minute.
[0072] As described above, and the difference between the
conventional technology and the present invention is that
performing high plating current density electroplating by disposing
a substrate or a component in an electroplating solution vibrated
by ultrasonic waves, thereby solving the problem of microstructure
inhomogeneity deposited via conventional high-speed electroplating,
and providing metal depositions with uniform microstructures.
[0073] Although the invention has been described with reference to
specific embodiments, this description is not meant to be construed
in a limiting sense. Various modifications of the disclosed
embodiments, as well as alternative embodiments, will be apparent
to persons skilled in the art. It is, therefore, contemplated that
the appended claims will cover all modifications that fall within
the true scope of the invention.
* * * * *