U.S. patent application number 13/596840 was filed with the patent office on 2012-12-20 for soft mold and method for fabricating the same.
This patent application is currently assigned to LG Display Co., Ltd.. Invention is credited to Gee Sung Chae, Gyoo Chul Jo, Jin Wuk Kim, Chang Hee Lee.
Application Number | 20120321739 13/596840 |
Document ID | / |
Family ID | 37566378 |
Filed Date | 2012-12-20 |
United States Patent
Application |
20120321739 |
Kind Code |
A1 |
Chae; Gee Sung ; et
al. |
December 20, 2012 |
SOFT MOLD AND METHOD FOR FABRICATING THE SAME
Abstract
A soft mold and a method for fabricating the same are disclosed.
A master mold that has a pattern on a substrate is first formed. A
first liquid high polymer precursor is formed on the master mold
and then partially cured. A support film having high UV
transmittance is attached to the partially cured high polymer. The
attached support film and the partially cured high polymer are
treated with a coupling agent and a second liquid high polymer
precursor is formed on the partially cured high polymer and the
support film. The second liquid high polymer precursor and the
partially cured high polymer are then fully cured to form a mold.
The fully cured mold is stripped from the master mold to form a
soft mold having a predetermined shape on one surface.
Inventors: |
Chae; Gee Sung; (Incheon,
KR) ; Jo; Gyoo Chul; (Gunpo-si, KR) ; Kim; Jin
Wuk; (Uiwang-si, KR) ; Lee; Chang Hee;
(Hwassong-si, KR) |
Assignee: |
LG Display Co., Ltd.
Seoul
KR
|
Family ID: |
37566378 |
Appl. No.: |
13/596840 |
Filed: |
August 28, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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|
11314637 |
Dec 20, 2005 |
8268214 |
|
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13596840 |
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Current U.S.
Class: |
425/385 |
Current CPC
Class: |
B29C 33/40 20130101;
B29C 33/3857 20130101; B29C 33/38 20130101 |
Class at
Publication: |
425/385 |
International
Class: |
B29C 59/02 20060101
B29C059/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 24, 2005 |
KR |
P2005-0055192 |
Claims
1. A soft mold comprising: a support film having UV transmittance
of about 95% or greater; and a mold surrounding the support film,
the mold having a surface containing a pattern.
2. The soft mold as claimed in claim 1, wherein the mold has a
thickness of about 1.5 mm to 6 mm.
3. The soft mold as claimed in claim 1, wherein the mold has a
substantially flat surface, the support film is arranged in the
mold substantially parallel with the substantially flat surface,
and the support film has a substantially uniform thickness.
4. The soft mold as claimed in claim 1, wherein the mold comprises
a fully cured elastic polymer or a high polymer equivalent to the
fully cured elastic polymer.
5. The soft mold as claimed in claim 4, wherein the mold comprises
at least one of PDMS, polyurethane, or polyimide.
Description
[0001] The present patent document is a divisional of U.S. patent
application Ser. No. 11/314,637, filed Dec. 20, 2005, which claims
priority to Korean Patent Application No. P2005-0055192 filed in
Korea on Jun. 24, 2005, which are hereby incorporated by
reference.
BACKGROUND
[0002] 1. Field of the Invention
[0003] The present invention relates to a soft mold for a fine
pattern, and more particularly, to a soft mold and a method for
fabricating the same, in which a support film is provided to
improve durability.
[0004] 2. Discussion of the Related Art
[0005] Generally, a soft mold is fabricated by casting rubber
(liquid high polymer precursor) in a mold such that the mold has a
pattern. The soft mold is used to form the inverted pattern on a
substrate using a particular material. For example, the soft mold
is used to form either a color filter on a color filter substrate
of a liquid crystal display device or an electrode in an organic
electroluminescent (EL) device.
[0006] Hereinafter, a related art process for fabricating a soft
mold will be described with reference to the accompanying drawings.
FIG. 1A to FIG. 1C are sectional views illustrating related art
process steps of fabricating a soft mold.
[0007] As shown in FIG. 1A, a master mold A is prepared to create a
predetermined shape on a surface of a soft mold. The master mold A
is formed by depositing an insulating material on an insulating
substrate 10 to form a preceding layer. The preceding layer is then
patterned by a photolithographic process to form a desired pattern
12.
[0008] As shown in FIG. 1B, once the master mold A is completed, an
elastic polymer (elastic rubber) solution of a pre-polymer state is
cast on the master mold A to form a pre-polymer layer 14.
[0009] Next, as shown in FIG. 1C, a polymer layer in which the
pre-polymer layer 14 is completely cured is referred to as a soft
mold 16. The soft mold 16 is stripped from the master mold (`A` of
FIG. 1B) so that the soft mold having a predetermined shape on its
surface is fabricated.
[0010] The soft mold fabricated as above is used in various fields
of soft lithography, soft molding, capillary force lithography, and
in-plane printing. For mass production of a product based on the
soft mold used in various fields, it is desirable that the soft
mold be aligned consistently. That is, it is desirable for the
material of the soft mold to retain its shape without contraction
or expansion even after the material is used several times.
However, the soft mold formed in a single structure as above
contracts or expands due to deformation if it is used several
times. For this reason, it is difficult to exactly align the soft
mold.
BRIEF SUMMARY
[0011] By way of introduction only, a soft mold in one embodiment
includes a support film and a mold surrounding the support film.
The support film has UV transmittance of about 95% or greater. The
mold has a surface containing a pattern.
[0012] In another embodiment, a method of fabricating a soft mold
is provided. A first mold material is formed on a master mold,
which has a pattern on a substrate. The first mold material is
partially cured and a support film is attached to the partially
cured first mold material. A second mold material is formed on the
partially cured first mold material and the support film. The
second mold material and the partially cured first mold material
are then fully cured to form a soft mold. The soft mold is stripped
from the master mold. A surface of the stripped soft mold has an
inverse of the pattern.
[0013] In another embodiment, a method of forming a pattern on a
substrate is presented. A layer to be patterned is deposited on the
substrate. A soft mold contacts the layer. The soft mold includes a
mold that contains a support film having UV transmittance of about
95% or greater disposed therein. A surface of the soft mold that
contacts the layer contains an inverse of the pattern. The layer
and the soft mold are then separated.
[0014] It is to be understood that both the foregoing general
description and the following detailed description of the present
invention are exemplary and explanatory and are intended to provide
further explanation of the invention as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The accompanying drawings, which are included to provide a
further understanding of the invention and are incorporated in and
constitute a part of this application, illustrate embodiment(s) of
the invention and together with the description serve to explain
the principle of the invention. In the drawings:
[0016] FIG. 1A to FIG. 1C are sectional views illustrating related
art process steps of fabricating a soft mold;
[0017] FIG. 2 is a structural sectional view illustrating a soft
mold according to the present invention; and
[0018] FIG. 3A to FIG. 3F are sectional views illustrating process
steps of fabricating a soft mold according to the embodiment of the
present invention.
DETAILED DESCRIPTION OF THE DRAWINGS AND THE PRESENTLY PREFERRED
EMBODIMENTS
[0019] Reference will now be made in detail to the preferred
embodiments of the present invention, examples of which are
illustrated in the accompanying drawings. Wherever possible, the
same reference numbers will be used throughout the drawings to
refer to the same or like parts.
[0020] A soft mold and a method for fabricating the same according
to the preferred embodiment of the present invention will be
described with reference to the accompanying drawings.
[0021] First, a soft mold according to the embodiment of the
present invention will be described. FIG. 2 is a structural
sectional view illustrating a soft mold according to the present
invention.
[0022] As shown in FIG. 2, the soft mold according to the present
invention includes a support film 33 having high UV transmittance,
and a mold 35 surrounding the support film 33. The mold 35 has an
uneven lower surface containing a predetermined pattern and a
substantially flat upper surface. The support film 33 is formed
using one or more two-way sheets having a uniform thickness.
[0023] A fully cured high polymer is used as the mold 35. The mold
35 can be fabricated by curing an elastic polymer. PDMS is widely
used as the elastic polymer, although other materials such as
polyurethane or polyimide (or a combination thereof) may be used.
More specifically, in one embodiment, the mold 35 is formed by
curing an elastic polymer solution. The elastic polymer solution in
one embodiment is a mixture of a pre-polymer with a curing agent at
a ratio of 10:1.
[0024] In one embodiment, the soft mold is formed by inserting the
support film 33 into the mold 35. This prevents the mold 35 from
being deformed (e.g. contracting or expanding) during formation
and/or use. The support film 33 has an ultraviolet (UV)
transmittance of about 95% or greater and is arranged in the mold
35 substantially parallel with the planar upper surface of the mold
35. The high amount of UV transmittance of the support film 33
permits UV irradiation of a fine pattern formed on a substrate
using the completed soft mold through the soft mold.
[0025] A method for fabricating the aforementioned soft mold
according to the embodiment of the present invention will now be
described. FIG. 3A to FIG. 3F are sectional views illustrating
process steps of fabricating a soft mold according to the first
embodiment of the present invention.
[0026] First, as shown in FIG. 3A, a master mold M is prepared to
form a predetermined shape on a surface of a soft mold. The master
mold M is formed by depositing an insulating material on an
insulating substrate 30 such as a silicon substrate or a glass
substrate to form a preceding layer. The preceding layer is
patterned by a photolithographic process to form a desired pattern
31. The pattern 31' on the substrate 30 may be formed of an
inorganic material such as Si3N4, SiO2, a metal, photoresist, or
wax.
[0027] As shown in FIG. 3B, when the master mold M is completed, an
elastic polymer (elastic rubber) of a pre-polymer state or a high
polymer material equivalent to the elastic polymer is cast on the
master mold M to form a first liquid high polymer precursor 32. The
elastic polymer may be formed of PDMS, polyurethane, and/or
polyimide. The first liquid high polymer precursor 32 has a
thickness of about 0.5 mm to 3 mm, for example about 1 mm. Note
that the about prefacing all ranges pertains to both the first and
last value. Thus, in the above example, the thickness of the first
liquid high polymer precursor 32 extends from about 0.5 mm to about
3 mm.
[0028] A mixture of pre-polymer with a curing agent at a mixture
ratio of 10:1 is used as the elastic polymer solution of the
pre-polymer state. Other mixture ratios such as 1:1 may be used
depending on the material of the elastic polymer.
[0029] Subsequently, the first liquid high polymer precursor 32 is
partially cured. More specifically, the first liquid high polymer
precursor 32 may be cured for about two hours to two days at a
temperature of about 25.degree. C. For example, the first liquid
high polymer precursor 32 may be cured for about one day at a
temperature of about 25.degree. C.
[0030] Next, as shown in FIG. 3C, the support film 33 is attached
to the partially cured high polymer 32a. Care is taken to avoid
forming bubbles in the partially cured high polymer 32a underneath
the support film 33 when depositing the support film 33. The
support film 33 may contain PET and have a thickness of about 0.1
mm to 1 mm. In addition, the support film 33 has UV transmittance
of about 95% or greater. Alternatively, other films having UV
transmittance of about 95% or greater may be used as the support
film.
[0031] When the support film 33 is fixed to the partially cured
high polymer 32a, the support film 33 is pushed by a rubber roller.
This improves the adhesion and helps to remove bubbles formed
between the support film 33 and the partially cured high polymer
32a.
[0032] Subsequently, the contour of the support film 33 and the
corner (portion defined by `C`) of the partially cured high polymer
32a are treated with a coupling agent. The coupling agent treatment
improves adhesion between the partially cured high polymer 32a and
a second liquid high polymer precursor 34 (shown in FIG. 3D). The
coupling agent treatment also aids in fixing the support film 33 to
the partially cured high polymer 32a. The coupling agent treatment
is performed using a primer. The coupling agent may also be applied
to the partially cured high polymer 32a before the support film 33
is fixed to the partially cured high polymer 32a.
[0033] After providing the coupling agent treatment, as shown in
FIG. 3D, the second liquid high polymer precursor 34 is cast on the
partially cured high polymer 32a including the support film 33. The
second liquid high polymer precursor 34 may have a thickness of
about 1 mm to 3mm, e.g. about 2 mm. The first and second liquid
high polymer precursors 32, 34 may comprise the same or different
materials.
[0034] Next, as shown in FIG. 3E, the second liquid high polymer
precursor 34 and the partially cured high polymer 32a are fully
cured to form a mold 35. This curing process is performed for about
one day to ten days, e.g. about seven days, at a temperature of
about 25.degree. C. Alternatively, the curing process may be
performed for about one hour at a temperature of about 80.degree.
C. However, in this latter case, the mold is more liable to become
deformed. In addition, the second liquid high polymer precursor 34
and the partially cured high polymer 32a may be fully cured using
UV irradiation in addition to/instead of temperature curing. In
this case, as the support film 33 has high UV transmittance, UV
radiation can be delivered throughout the structure being cured,
e.g. to the material of the mold through the support film 33.
[0035] Then, as shown in FIG. 3F, the mold 35 containing the
support film 33 is stripped from the master mold M. Thus, the soft
mold is created with a predetermined shape on one surface.
[0036] Soft molds having a support film and soft molds without a
support film were fabricated as described above. The soft molds
underwent soft lithography to measure deformation of the mold. The
results are shown in Table 1.
TABLE-US-00001 TABLE 1 Type of mold Deformation of mold Support
film not inserted 10,000 .+-. 1,000 ppm Support film inserted 212
.+-. 8 ppm
[0037] As shown in Table 1, the mold deforms (e.g.
contracts/expands) less during use if the support film is inserted
into the mold than if the support film is not inserted into the
mold. The ratio of the amount of deformation is about 50:1 for a
mold that does not have a support film to a mold that contains a
support film.
[0038] Thus, since the support film is inserted into the mold,
deformation of the mold can be decreased and thereby durability of
the mold can be improved. Accordingly, the mold is more suitable
for mass production as the durability increases.
[0039] It will be apparent to those skilled in the art that various
modifications and variations can be made in the present invention
without departing from the spirit or scope of the inventions. Thus,
it is intended that the present invention covers the modifications
and variations of this invention provided they come within the
scope of the appended claims and their equivalents.
* * * * *