U.S. patent application number 13/876662 was filed with the patent office on 2013-08-22 for electrical element package.
The applicant listed for this patent is Noriaki Masuda, Takeshi Sakurai, Toru Shiragami, Hiroki Yamazaki, Yasuo Yamazaki. Invention is credited to Noriaki Masuda, Takeshi Sakurai, Toru Shiragami, Hiroki Yamazaki, Yasuo Yamazaki.
Application Number | 20130213852 13/876662 |
Document ID | / |
Family ID | 45893224 |
Filed Date | 2013-08-22 |
United States Patent
Application |
20130213852 |
Kind Code |
A1 |
Yamazaki; Yasuo ; et
al. |
August 22, 2013 |
ELECTRICAL ELEMENT PACKAGE
Abstract
Provided is an electrical element package, comprising an element
substrate on which an electrical element is provided, a sealing
substrate provided at a distance from a surface of the element
substrate on a side of the electrical element so as to be opposed
to the element substrate, and a glass frit for hermetically sealing
a gap between the element substrate and the sealing substrate so as
to surround the electrical element, wherein the electrical element
package comprises a protective film for protecting an electrode
from laser light applied in welding the glass frit, the protective
film being provided between the element substrate and the glass
frit.
Inventors: |
Yamazaki; Yasuo; (Shiga,
JP) ; Shiragami; Toru; (Shiga, JP) ; Masuda;
Noriaki; (Shiga, JP) ; Sakurai; Takeshi;
(Shiga, JP) ; Yamazaki; Hiroki; (Shiga,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Yamazaki; Yasuo
Shiragami; Toru
Masuda; Noriaki
Sakurai; Takeshi
Yamazaki; Hiroki |
Shiga
Shiga
Shiga
Shiga
Shiga |
|
JP
JP
JP
JP
JP |
|
|
Family ID: |
45893224 |
Appl. No.: |
13/876662 |
Filed: |
September 30, 2011 |
PCT Filed: |
September 30, 2011 |
PCT NO: |
PCT/JP2011/072527 |
371 Date: |
April 25, 2013 |
Current U.S.
Class: |
206/701 |
Current CPC
Class: |
H05B 33/04 20130101;
C03C 3/19 20130101; C03C 8/08 20130101; C03C 8/24 20130101; B65D
85/00 20130101; H01L 2924/16195 20130101; H01L 51/5246
20130101 |
Class at
Publication: |
206/701 |
International
Class: |
B65D 85/00 20060101
B65D085/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 1, 2010 |
JP |
2010-223888 |
Nov 25, 2010 |
JP |
2010-261986 |
Claims
1. An electrical element package, comprising: an element substrate
on which an electrical element is provided; a sealing substrate
provided at a distance from a surface of the element substrate on a
side of the electrical element so as to be opposed to the element
substrate; and a glass frit for hermetically sealing a gap between
the element substrate and the sealing substrate so as to surround
the electrical element, wherein the electrical element package
comprises a protective film for protecting an electrode from laser
light applied in welding the glass frit, the protective film being
provided between the element substrate and the glass frit.
2. An electrical element package, comprising: an element substrate
on which an electrical element is provided; a sealing substrate
provided at a distance from a surface of the element substrate on a
side of the electrical element so as to be opposed to the element
substrate; and a glass frit for hermetically sealing a gap between
the element substrate and the sealing substrate so as to surround
the electrical element, wherein: the electrical element package
comprises a reflective film for reflecting laser light applied in
welding the glass frit, the reflective film being provided between
the element substrate and the glass frit; and the reflective film
is formed of a multilayer dielectric film obtained by alternately
laminating a low-refractive index dielectric layer and a
high-refractive index dielectric layer.
3. The electrical element package according to claim 2, wherein the
multilayer dielectric film is welded directly to the glass
frit.
4. The electrical element package according to claim 2, wherein the
multilayer dielectric film is formed directly on an electrode
connected to the electrical element.
5. The electrical element package according to claim 2, wherein the
low-refractive index dielectric layer has a refractive index of 1.6
or less, and the high-refractive index dielectric layer has a
refractive index of 1.7 or more.
6. The electrical element package according to claim 2, wherein the
multilayer dielectric film has a reflectance of 50% or more to the
laser light.
7. The electrical element package according to claim 2, wherein the
glass frit contains 80 to 99.7 mass % of inorganic powder
comprising SnO-containing glass powder and 0.3 to 20 mass % of a
pigment.
8. The electrical element package according to claim 7, wherein the
SnO-containing glass powder contains, as a glass composition in
terms of mol %, 35 to 70% of SnO and 10 to 30% of
P.sub.2O.sub.5.
9. An electrical element package, comprising: an element substrate
on which an electrical element is provided; a sealing substrate
provided at a distance from a surface of the element substrate on a
side of the electrical element so as to be opposed to the element
substrate; and a glass frit for hermetically sealing a gap between
the element substrate and the sealing substrate so as to surround
the electrical element, wherein the electrical element package
comprises a metal oxide film for protecting an electrode from laser
light applied in welding the glass frit, the film being provided
between the element substrate and the glass frit.
10. The electrical element package according to claim 9, wherein
the metal oxide film has a thickness of 10 to 500 nm.
11. The electrical element package according to claim 9, wherein
the metal oxide film comprises any one of SiO.sub.2, ZrO.sub.2,
Y.sub.2O.sub.3, TiO.sub.2, Al.sub.2O.sub.3, Ta.sub.2O.sub.5, and
Nb.sub.2O.sub.5.
12. The electrical element package according to claim 9, wherein
the metal oxide film is welded directly to the glass frit.
13. The electrical element package according to claim 9, wherein
the metal oxide film is formed directly on an electrode connected
to the electrical element.
14. The electrical element package according to claim 9, wherein
the glass frit contains 80 to 99.5 mass % of inorganic powder
comprising SnO-containing glass powder and 0.05 to 20 mass % of a
pigment.
15. The electrical element package according to claim 14, wherein
the SnO-containing glass powder contains, as a glass composition in
terms of mol %, 35 to 70% of SnO and 10 to 30% of P.sub.2O.sub.5.
Description
TECHNICAL FIELD
[0001] The present invention relates to an electrical element
package in which an electrical element such as an OLED, sensitive
to an ambient environment, is hermetically sealed to prevent
deterioration caused by oxygen, water, and the like in the ambient
environment.
BACKGROUND ART
[0002] As is known, there have been made various research and
development activities on an OLED display device (OLED display). In
some fields such as a small-sized display device used for a cellar
phone or the like, the OLED display device has already been put
into practical use.
[0003] An OLED element (OLED layer) used for the OLED display
device is a sensitive element which easily deteriorates when
exposed to oxygen or water in an ambient environment. Therefore,
for the practical use, the OLED layer is incorporated into the OLED
display device in a state in which the layer is hermetically sealed
so as to maintain display quality of the device and prolong a
lifetime thereof.
[0004] An OLED element package in which an OLED layer is
hermetically sealed generally has a structure in which a sealing
substrate is provided at a distance from an element substrate on
which the OLED layer is provided so as to be opposed to the element
substrate, and a gap between the element substrate and the sealing
substrate is hermetically sealed with a glass frit so as to
surround the OLED layer provided on the element substrate. At this
time, laser light is applied from the sealing substrate side to
heat the glass frit so that the glass frit softens to be welded to
the element substrate and the sealing substrate, to thereby form a
hermetically sealed structure.
[0005] When the laser light is applied to the glass frit, however,
an electrode (for example, an ITO electrode) for supplying electric
power from the exterior to the OLED layer and the OLED layer may be
damaged by irradiation heat of the laser light. The reason is as
follows. Specifically, the electrode for supplying electric power
from the exterior to the OLED layer is provided below the glass
frit. Therefore, if no countermeasure against the irradiation heat
of the laser light is taken, the electrode located below the glass
frit is unduly heated by the irradiation heat of the laser light to
be thermally damaged and, in some cases, disconnection may occur.
Moreover, if the electrode is heated as described above, the heat
may be transmitted through the electrode to the OLED layer to bring
about a situation in which the OLED layer is thermally damaged.
[0006] Therefore, in general, when the OLED element package is
manufactured, various countermeasures against heat, for preventing
the irradiation heat of the laser light from being transmitted to
the electrode or the OLED layer, are implemented.
[0007] For example, Patent Literatures 1 and 2 disclose that a
laminate of a metal layer and an improvement layer for improving an
adhesive force is provided on a substrate side on which an OLED
element is provided, and a glass frit is welded to the improvement
layer so as to join a substrate on which the OLED layer is
provided, and a substrate opposed thereto. With this, even if laser
light is applied in welding the glass frit, the laser light can be
reflected by the metal layer. Therefore, the transmission of the
irradiation heat of the laser light to the electrode connected to
the OLED layer becomes hard. Thus, an effect of preventing the
electrode and the OLED layer from being thermally damaged can be
expected.
CITATION LIST
[0008] Patent Literature 1: JP 2010-80341 A [0009] Patent
Literature 2: JP 2010-80339 A
SUMMARY OF INVENTION
Technical Problem
[0010] In the case where the metal layer functioning as a
reflective film for reflecting the laser light is used as disclosed
in Patent Literatures 1 and 2, however, if the glass frit is
directly welded to the metal layer, an adhesive force therebetween
cannot be sufficiently maintained. Therefore, it is indispensably
necessary to provide the improvement layer for improving the
adhesive force between the metal layer and the glass frit.
Moreover, when the metal layer is held in contact with the
electrode connected to the OLED element, there arises a problem in
that the metal layer and the electrode become conductive to each
other. Therefore, it becomes also indispensably necessary to
provide an insulating layer between the metal layer and the
electrode. Therefore, a problem of a lowered degree of freedom in
design of the OLED element package may arise.
[0011] It should be noted that, although the OLED element has been
described above as an example, the same problem may arise even for
an electrical element other than the OLED element when the
electrical element is liable to be affected by an external
environment and is hermetically sealed with the glass frit.
Moreover, even in other fields such as a lighting device and a
solar cell as well as the display device, the same problem may
arise when the electrical element package is used.
[0012] In view of the current conditions described above, a
technical object of the present invention is to reduce a situation
in which an electrode or an electrical element is damaged by
irradiation heat of laser light applied in welding a glass frit as
much as possible while ensuring the degree of freedom in design of
an electrical element package.
Solution to Problem
[0013] In order to achieve the technical object as above, the
present invention provides an electrical element package,
comprising, an element substrate on which an electrical element is
provided, a sealing substrate provided at a distance from a surface
of the element substrate on a side of the electrical element so as
to be opposed to the element substrate, and a glass frit for
hermetically sealing a gap between the element substrate and the
sealing substrate so as to surround the electrical element, wherein
the electrical element package comprises a protective film for
protecting an electrode from laser light applied in welding the
glass frit, the protective film being provided between the element
substrate and the glass frit. The present invention includes, as
specific embodiments thereof, a first aspect and a second aspect
shown below.
[0014] The first aspect of the present invention is an electrical
element package, comprising, an element substrate on which an
electrical element is provided, a sealing substrate provided at a
distance from a surface of the element substrate on a side of the
electrical element so as to be opposed to the element substrate, a
glass frit for hermetically sealing a gap between the element
substrate and the sealing substrate so as to surround the
electrical element, and a reflective film for reflecting laser
light applied in welding the glass frit, the film being provided
between the element substrate and the glass frit, wherein the
reflective film is formed of a multilayer dielectric film obtained
by alternately laminating a low-refractive index dielectric layer
and a high-refractive index dielectric layer.
[0015] According to the configuration described above, the
reflective film for reflecting the laser light applied in welding
the glass frit is formed of the multilayer dielectric film obtained
by alternately laminating the low-refractive index dielectric layer
and the high-refractive index dielectric layer. The dielectric
layers constituting the multilayer dielectric film have excellent
adhesiveness to the glass frit. Therefore, even without
additionally providing a bonding-force improvement layer only for
increasing the adhesive force to the glass frit, in addition to the
multilayer dielectric film, the adhesive force to the glass frit
can be well maintained. Moreover, the dielectric layers
constituting the multilayer dielectric film do not have
conductivity. Therefore, even without additionally providing an
insulating layer, electric insulation from the electrode connected
to the electrical element can be maintained. Accordingly,
additionally providing the bonding-force improvement layer for
improving the adhesive force to the glass frit and the insulating
layer is not an indispensable condition. As a result, the degree of
freedom in the design of the electrical element package can be
ensured.
[0016] Moreover, with the multilayer dielectric film as described
above, a high reflectance can be easily realized in a wavelength
band of the used laser light by selecting a material and adjusting
a thickness for each of the low-refractive index dielectric layer
and the high-refractive index dielectric layer. Therefore, when the
laser light is applied to weld the frit glass, the laser light is
reliably reflected at the multilayer dielectric film toward the
frit glass so as to be effectively used to heat the frit glass.
Therefore, the laser light transmitted through the multilayer
dielectric film to be applied to the electrode or the like is
reduced as much as possible. Accordingly, it becomes possible to
reliably prevent a situation in which the electrode or the
electrical element is unduly heated by the laser light to be
thermally damaged.
[0017] In the above-mentioned configuration, the multilayer
dielectric film may be welded directly to the glass frit, or the
multilayer dielectric film may be formed directly on an electrode
connected to the electrical element.
[0018] Specifically, as already described above, the multilayer
dielectric film has a high adhesive force to the glass frit and
insulation property, and therefore can be directly welded to the
glass frit or directly formed on the electrode connected to the
electrical element. With this, the configuration of the electrical
element package is simplified to facilitate the manufacturing.
[0019] In the above-mentioned configuration, it is preferred that
the low-refractive index dielectric layer have a refractive index
of 1.6 or less, and the high-refractive index dielectric layer have
a refractive index of 1.7 or more.
[0020] With this, a difference in refractive index between the
low-refractive index dielectric layer and the high-refractive index
dielectric layer can be appropriately kept so as to well maintain
the reflectance to the laser light.
[0021] In the above-mentioned configuration, it is preferred that
the multilayer dielectric film have a reflectance of 50% or more to
the laser light.
[0022] With this, most part of the laser light applied in welding
the glass frit can be reflected toward the glass frit. Therefore,
it is possible to more reliably prevent a situation in which the
electrode or the electrical element is damaged by the irradiation
heat of the laser light.
[0023] In the above-mentioned configuration, the glass frit may
contain 80 to 99.7 mass % of inorganic powder comprising
SnO-containing glass powder and 0.3 to 20 mass % of a pigment.
Herein, the term "SnO-containing glass powder" means glass powder
containing, as a glass composition, 20 mol % or more of SnO.
Moreover, the term "inorganic powder" means powder of an inorganic
material other than (excepting) a pigment and generally means a
mixture of glass powder and a refractory filler.
[0024] With this, the glass frit comprises the SnO-containing glass
powder. Therefore, a softening point of the glass powder is lowered
to lower a softening point of the whole glass frit. Then, when the
inorganic powder comprising the SnO-containing glass powder is set
within the above-mentioned range, the softening point of the glass
frit is adequately lowered. Therefore, welding (sealing) with the
laser light can be completed within a short period of time, whereas
a welding strength thereof can also be increased. It should be
noted that, if the content of the inorganic powder is less than 80
mass %, the glass frit does not soften and flow sufficiently when
welding with laser light, and therefore, it becomes difficult to
maintain a high welding strength.
[0025] Further, the glass frit contains 0.3 to 20 mass % of the
pigment. When the content of the pigment is controlled to 0.3 mass
% or more, the laser light becomes more likely to be absorbed by
the glass frit. Therefore, the irradiation heat of the laser light
can efficiently act on the glass frit. Thus, only a portion of the
glass frit, which is to be welded, is more likely to be locally
heated. As a result, the electrode and the electrical element can
be prevented from being thermally damaged. On the other hand, when
the content of the pigment is restricted to 20 mass % or less, a
situation in which the glass frit devitrifies can be prevented when
the glass frit is welded by the irradiation heat of the laser
light.
[0026] In this case, the SnO-containing glass powder may contain,
as a glass composition in terms of mol %, 35 to 70% of SnO and 10
to 30% of P.sub.2O.sub.5.
[0027] With this, the water resistance of the glass frit can be
easily increased while a low-melting-point characteristic of the
glass frit is maintained.
[0028] Next, the second aspect of the present invention is an
electrical element package, comprising, an element substrate on
which an electrical element is provided, a sealing substrate
provided at a distance from a surface of the element substrate on a
side of the electrical element so as to be opposed to the element
substrate, and a glass frit for hermetically sealing a gap between
the element substrate and the sealing substrate so as to surround
the electrical element, wherein the electrical element package
comprises a metal oxide film for protecting an electrode from laser
light applied in welding the glass frit, the film being provided
between the element substrate and the glass frit.
[0029] According to the configuration described above, the metal
oxide film is formed between the element substrate and the glass
frit. Therefore, when the laser light is applied to the glass frit
to melt the glass frit, that is, at the time of laser welding, the
contact between the glass frit and the electrode can be avoided as
much as possible while the heat generated by the applied laser
light is suppressed.
[0030] Further, according to the configuration described above, a
high welding strength can be obtained even without additionally
providing an improvement layer for increasing the adhesive force to
the glass frit. Moreover, the metal oxide film does not have
conductivity. Therefore, the electric insulation from the electrode
connected to the electrical element can be maintained even without
additionally providing the insulating layer. As a result, the
degree of freedom in the design of the electrical element package
is improved, which in turn leads to a reduction in the
manufacturing cost of the electrical element package.
[0031] In the above-mentioned configuration, it is preferred that
the metal oxide film have a thickness of 10 to 500 nm. With this,
the electrode can be reliably protected while separation occurring
between the glass frit and the metal oxide film after the laser
welding is prevented.
[0032] In the above-mentioned configuration, it is preferred that
the metal oxide film comprise any one of SiO.sub.2, ZrO.sub.2,
Y.sub.2O.sub.3, TiO.sub.2, Al.sub.2O.sub.3, Ta.sub.2O.sub.5, and
Nb.sub.2O.sub.5. Such the metal oxide films have particularly
excellent adhesiveness to the glass frit and insulating
property.
[0033] In the above-mentioned configuration, it is preferred that
the metal oxide film be welded directly to the glass frit, or
formed directly on an electrode connected to the electrical
element. With this, the configuration of the electrical element
package can be simplified. Therefore, the manufacturing efficiency
of the electrical element package is improved. As described above,
the metal oxide film is excellent in adhesive force to the glass
frit as well as in insulating property. Therefore, the metal oxide
film can be directly welded to the glass frit, or the metal oxide
film can be directly formed on the electrode connected to the
electric element.
[0034] In the above-mentioned configuration, it is preferred that
the glass frit contain 80 to 99.5 mass % of inorganic powder
comprising SnO-containing glass powder and 0.05 to 20 mass % of a
pigment. With this, the glass frit comprises the SnO-containing
glass powder. Therefore, a softening point of the glass powder is
lowered to lower a softening point of the glass frit. Then, when
the inorganic powder comprising the SnO-containing glass powder is
set within the above-mentioned range, the softening point of the
glass frit is adequately lowered. Therefore, laser welding can be
completed within a short period of time, whereas a welding strength
thereof can also be increased.
[0035] In this case, it is preferred that the SnO-containing glass
powder contain, as a glass composition in terms of mol %, 35 to 70%
of SnO and 10 to 30% of P.sub.2O.sub.5. With this, the water
resistance of the glass frit can be easily increased while a
low-melting-point characteristic of the glass frit is
maintained.
Advantageous Effects of Invention
[0036] As described above, according to the present invention, it
is possible to reduce a situation in which the electrode or the
electrical element is damaged by the irradiation heat of the laser
light applied in welding the glass frit as much as possible while
the degree of freedom in the design of the electrical element
package is ensured.
BRIEF DESCRIPTION OF DRAWINGS
[0037] FIG. 1 A longitudinal sectional view illustrating a
schematic configuration of an OLED element package according to an
embodiment of the first aspect of the present invention.
[0038] FIG. 2 A sectional view taken along the line A-A in FIG.
1.
[0039] FIG. 3 A longitudinal sectional view illustrating a
schematic configuration of an OLED element package according to an
embodiment of the second aspect of the present invention.
[0040] FIG. 4 A sectional view taken along the line A-A in FIG.
3.
[0041] FIG. 5 A graph showing the results of simulation of
frequency characteristics of reflectance of multilayer dielectric
films.
[0042] FIG. 6 A graph showing the results of actual measurement of
frequency characteristics of reflectance of multilayer dielectric
films.
[0043] FIG. 7 A graph showing the results of actual measurement of
temperature of electrodes at the time of laser welding.
[0044] FIG. 8 A graph showing the results of actual measurement of
temperature of electrodes at the time of laser welding.
[0045] FIG. 9 A graph showing the results of actual measurement of
temperature of glass frits at the time of laser welding.
[0046] FIG. 10 A schematic diagram illustrating a softening point
of glass powder (SnO-containing glass powder) or a glass frit when
measured with a macro-type DTA apparatus.
DESCRIPTION OF EMBODIMENTS
[0047] First, an embodiment of the first aspect of the present
invention is described referring to the accompanying drawings. It
should be noted that an OLED element package to be incorporated
into an OLED display device is described below as an example of an
electrical element package.
[0048] FIG. 1 is a longitudinal sectional view illustrating a
schematic configuration of an OLED element package according to
this embodiment. An OLED element package 1 comprises, as a basic
configuration, an element substrate 3 on which an OLED layer 2 is
formed, a sealing substrate 4 provided opposite to the element
substrate 3 at a distance from a surface of the element substrate 3
on the OLED layer 2 side, and a glass frit 5 for surrounding the
OLED layer 2 in a frame-like fashion so as to hermetically seal a
gap between the element substrate 3 and the sealing substrate
4.
[0049] Each of the element substrate 3 and the sealing substrate 4
is formed of a glass substrate having a thickness of, for example,
0.05 to 0.7 mm in this embodiment.
[0050] A first electrode 6 and a second electrode 7, which are
respectively connected to a back side and a front side of the OLED
layer 2, are provided on the element substrate 3. The electrodes 6
and 7 pass below the glass frit 5 to be guided from the OLED layer
2 to the exterior of the package 1 so as to supply electric power
to the OLED layer 2. It should be noted that the electrodes 6 and 7
branch according to a predetermined pattern, as illustrated in FIG.
2. The first electrode 6 on the back surface side of the OLED layer
2 is formed of, for example, a transparent electrode film (ITO
film), whereas the second electrode 7 on the front surface side of
the OLED layer is formed of, for example, a metal electrode film
such as aluminum. It should be noted that the first electrode 6 and
the second electrode 7 may both be formed of a transparent
electrode film.
[0051] Then, as illustrated in FIGS. 1 and 2, laser light emitted
from a laser L is applied from the sealing substrate 4 side to the
glass frit 5 to heat the glass frit 5 so that the glass frit
softens and flows to be welded to the element substrate 3 and the
sealing substrate 4. With this, a hermetically-sealed structure of
the package 1 is formed. As the laser L, for example, an
infrared-ray laser (having a wavelength of 700 to 2500 nm) is
used.
[0052] If the electrodes 6 and 7 are heated by irradiation heat of
the laser light when the glass frit 5 is welded, there is a
possibility of thermally damaging the electrodes 6 and 7. Moreover,
there is another possibility of transmitting the heat through the
electrodes 6 and 7 to the OLED layer 2 to thermally damage the OLED
layer 2. Therefore, in this embodiment, a multilayer dielectric
film 8 functioning as a reflective film is provided between the
glass frit 5 and each of the electrodes 6 and 7 so as to reflect
the laser light to the glass frit 5 side corresponding to the side
opposite to the electrodes 6 and 7.
[0053] The multilayer dielectric film 8 is formed by alternately
laminating a low-refractive index dielectric layer and a
high-refractive index dielectric layer, and is set to have a
reflectance of 50% or more (preferably 90% or more) in a wavelength
band of the used laser light (for example, at 808 nm).
[0054] Specifically, the low-refractive index dielectric layer is
made of a material having a refractive index of 1.6 or less,
preferably a refractive index of 1.33 to 1.6. Examples of such
material include silica (SiO.sub.2), alumina (Al.sub.2O.sub.3),
lanthanum fluoride (LaF.sub.3), magnesium fluoride (MgF.sub.2), and
sodium aluminum hexafluoride (Na.sub.3AlF.sub.6). When the
refractive index and thickness of the low-refractive index
dielectric layer is defined as n1 and d1, respectively, and a
wavelength of the laser light is defined as .lamda., an optical
thickness (n1.times.d1) of the low-refractive index dielectric
layer is set to .lamda./4.
[0055] The high-refractive index dielectric layer is made of a
material having a refractive index of 1.7 or more, preferably a
refractive index of 1.7 to 2.5. Examples of such material include a
material obtained by adding small amount of titanium oxide
(TiO.sub.2), tin oxide (SnO), or cerium oxide (CeO.sub.2), to
titanium oxide (TiO.sub.2), zirconium oxide (ZrO.sub.2),
tantalumpentoxide (Ta.sub.2O.sub.5), niobiumpentoxide
(Nb.sub.2O.sub.5), lanthanum oxide (La.sub.2O.sub.3), silicon
nitride (Si.sub.3N.sub.4), yttrium oxide (Y.sub.2O.sub.3), zinc
oxide (ZnO), zinc sulfide (ZnS), or indium oxide (In.sub.2O.sub.3)
as a main component. When the refractive index and thickness of the
high-refractive index dielectric layer is defined as n2 and d2,
respectively, and a wavelength of the laser light is defined as
.lamda., an optical thickness (n2.times.d2) of the high-refractive
index dielectric layer is set to an integral multiple of .lamda./4.
It should be noted that, when the laser light having .lamda. of
1200 nm or more, SiO.sub.2 can also be used. When the laser light
having .lamda. of 1700 nm or more, GeO.sub.2 can also be used.
[0056] It should be noted that, as the multilayer dielectric film
8, the number of laminated low-refractive index dielectric layers
and high-refractive index dielectric layers is preferably four or
more in total.
[0057] Further, it is preferred to provide different thermal
expansion coefficients to the low-refractive index dielectric layer
and the high-refractive index dielectric layer of the multilayer
dielectric film 8. With this, as compared with the case where the
refractive film for the laser light is formed to have a single
layer, a stress due to thermal expansion at the time of welding
with the laser light is significantly relieved. As a result, a
crack is unlikely to be generated in the film. As a result, a
situation in which oxygen or water enters from a portion of the
multilayer dielectric film 8 can be reliably prevented. The reason
is as follows. Specifically, when a multilayer film is formed on a
substrate having a low thermal expansion coefficient such as glass,
the multilayer film with high reliability can be formed with a
laminated structure in which a layer having a compressive stress as
an internal stress and a layer having a tensile stress as an
internal stress are alternately laminated so that an internal
stress of the whole multilayer film becomes small. In particular,
an internal stress of the multilayer film formed on a substrate
having a low thermal expansion coefficient
(37.times.10.sup.-7/.degree. C. or less) such as alkali-free glass
exhibits the characteristics as described above. As a specific
example, when SiO.sub.2 which is a low-refractive index material
and TiO.sub.2 which is a high-refractive index material are
laminated on an alkali-free glass substrate, the internal stress of
the SiO.sub.2 film is likely to become a compressive stress,
whereas the internal stress of the TiO.sub.2 film is likely to
become a tensile stress. Therefore, the internal stresses of the
SiO.sub.2 film and the TiO.sub.2 film are cancelled out. As a
result, the internal stress becomes small as the whole multilayer
film.
[0058] Here, a material for the glass frit 5, for example, there
may be used a material comprising 80 to 99.7 mass % of inorganic
powder comprising SnO-containing glass powder and 0.3 to 20 mass %
of a pigment.
[0059] In this case, the content of the inorganic powder is
preferably 90 to 99 mass %, more preferably 95 to 99 mass %,
particularly preferably 97 to 99 mass %. If the content of the
inorganic powder is small, the glass frit 5 does not soften and
flow sufficiently at the time of welding, and it becomes difficult
to enhance the welding strength at the time of the welding. On the
other hand, if the content of the inorganic powder is more than
99.9 mass %, the content of the pigment becomes relatively small,
and hence laser-light absorption performance of the glass frit 5
itself decreases. On the other hand, if the content of the pigment
is too large, the thermal stability of glass is liable to
deteriorate.
[0060] The average particle diameter D.sub.50 of the SnO-containing
glass powder is preferably less than 15 .mu.m, more preferably 0.5
to 10 .mu.m, particularly preferably 1 to 5 .mu.m. When the average
particle diameter D.sub.50 of the SnO-containing glass powder is
restricted to less than 15 .mu.m, the gap between the element
substrate 3 and the sealing substrate 4 can be easily narrowed.
Accordingly, a time necessary for performing laser welding is
shortened, and cracks and the like do not easily occur in a welding
portion of the glass frit 5 even if there is a difference in
thermal expansion coefficient between each of the element substrate
3 and the sealing substrate 4 and the glass frit 5. Herein, the
term "average particle diameter D.sub.50" refers to a value
measured by laser diffractometry, and refers to a particle diameter
at which the cumulative amount of particles starting from a
particle having the smallest diameter reaches 50% in a cumulative
particle size distribution curve on a volumetric basis in the
measurement by laser diffractometry.
[0061] A maximum particle diameter D.sub.max of the SnO-containing
glass powder is preferably 30 .mu.m or less, more preferably 20
.mu.m or less, particularly preferably 10 .mu.m or less. When the
maximum particle diameter D.sub.max of the SnO-containing glass
powder is restricted to 30 .mu.m or less, the gap between the
element substrate 3 and the sealing substrate 4 can be easily
narrowed, and cracks and the like do not easily occur in a welding
portion of the glass frit 5, as in the above-mentioned case where
the average particle diameter is restricted. Herein, the term
"maximum particle diameter D.sub.max" refers to a value measured by
laser diffractometry, and refers to a particle diameter at which
the cumulative amount of particles starting from a particle having
the smallest diameter reaches 99% in a cumulative particle size
distribution curve on a volumetric basis in the measurement by
laser diffractometry.
[0062] The SnO-containing glass powder preferably contains 35 to
70% of SnO and 10 to 30% of P.sub.2O.sub.5 as a glass composition.
The reasons why the glass composition is limited to such the range
are described below. It should be noted that, in the description of
the range of a glass composition, the expression "%" refers to "mol
%" unless otherwise specified.
[0063] SnO is a component that contributes to lowering the melting
point of glass. The content of SnO is preferably 35% or more, more
preferably 35 to 70%, still more preferably 40 to 70%, most
preferably 50 to 68%. Particularly when the content of SnO is 50%
or more in glass, the glass easily softens and flows at the time of
laser welding. If the content of SnO is less than 35% in glass, the
viscosity of the glass becomes too high and it becomes difficult to
perform laser welding with a desired laser output. On the other
hand, if the content of SnO is more than 70% in glass, the
vitrification of the glass is liable to be difficult.
[0064] P.sub.2O.sub.5 is a glass-forming oxide and is a component
that enhances the thermal stability of glass. The content of
P.sub.2O.sub.5 is preferably 10 to 30%, more preferably 15 to 27%,
particularly preferably 15 to 25%. If the content of P.sub.2O.sub.5
is less than 10% in glass, the thermal stability of the glass is
liable to deteriorate. On the other hand, if the content of
P.sub.2O.sub.5 is more than 30% in glass, the weather resistance of
the glass deteriorates, and hence it becomes difficult to ensure
the long-term reliability of the OLED element package.
[0065] The following components can be added in addition to the
above-mentioned components.
[0066] ZnO is an intermediate oxide and is a component that
stabilizes glass. The content of ZnO is preferably 0 to 30%, more
preferably 1 to 20%, particularly preferably 1 to 15%. If the
content of ZnO is more than 30% in glass, the thermal stability of
the glass may be liable to deteriorate.
[0067] B.sub.2O.sub.3 is a glass-forming oxide, is a component that
stabilizes glass, and is a component that enhances the weather
resistance of glass. The content of B.sub.2O.sub.3 is preferably 0
to 20%, more preferably 1 to 20%, particularly preferably 2 to 15%.
If the content of B.sub.2O.sub.3 is more than 20% in glass, the
viscosity of the glass may become too high and it may become
difficult to perform laser welding with a desired laser output.
[0068] Al.sub.2O.sub.3 is an intermediate oxide and is a component
that stabilizes glass. Further, Al.sub.2O.sub.3 is a component that
lowers the thermal expansion coefficient of glass. The content of
Al.sub.2O.sub.3 is preferably 0.1 to 10%, particularly preferably
0.5 to 5%. If the content of Al.sub.2O.sub.3 is more than 10% in
glass powder, the softening point of the glass powder improperly
may rise and it may become difficult to perform laser welding with
a desired laser output.
[0069] SiO.sub.2 is a glass-forming oxide and is a component that
stabilizes glass. The content of SiO.sub.2 is preferably 0 to 15%,
particularly preferably 0 to 5%. If the content of SiO.sub.2 is
more than 15% in glass powder, the softening point of the glass
powder may improperly rise and it may become difficult to perform
laser welding with a desired laser output.
[0070] In.sub.2O.sub.3 is a component that enhances the thermal
stability of glass and the content of In.sub.2O.sub.3 is preferably
0 to 5%. If the content of In.sub.2O.sub.3 is more than 5%, batch
cost may rise.
[0071] Ta.sub.2O.sub.5 is a component that enhances the thermal
stability of glass and the content of Ta.sub.2O.sub.5 is preferably
0 to 5%. If the content of Ta.sub.2O.sub.5 is more than 5% in glass
powder, the softening point of the glass powder may improperly rise
and it may become difficult to perform laser welding with a desired
laser output.
[0072] La.sub.2O.sub.3 is a component that enhances the thermal
stability of glass and is a component that enhances the weather
resistance of glass. The content of La.sub.2O.sub.3 is preferably 0
to 15%, more preferably 0 to 10%, particularly preferably 0 to 5%.
If the content of La.sub.2O.sub.3 is more than 15%, batch cost may
rise.
[0073] MoO.sub.3 is a component that enhances the thermal stability
of glass and the content of MoO.sub.3 is preferably 0 to 5%. If the
content of MoO.sub.3 is more than 5% in glass powder, the softening
point of the glass powder may improperly rise and it may become
difficult to perform laser welding with a desired laser output.
[0074] WO.sub.3 is a component that enhances the thermal stability
of glass and the content of WO.sub.3 is preferably 0 to 5%. If the
content of WO.sub.3 is more than 5% in glass powder, the softening
point of the glass powder may improperly rise and it may become
difficult to perform laser welding with a desired laser output.
[0075] Li.sub.2O is a component that contributes to lowering
melting point of glass and the content of Li.sub.2O is preferably 0
to 5%. If the content of Li.sub.2O is more than 5% in glass, the
thermal stability of the glass may be liable to deteriorate.
[0076] Na.sub.2O is a component that contributes to lowering
melting point of glass and the content of Na.sub.2O is preferably 0
to 10%, particularly preferably 0 to 5%. If the content of
Na.sub.2O is more than 10% in glass, the thermal stability of the
glass may be liable to deteriorate.
[0077] K.sub.2O is a component that contributes to lowering melting
point of glass and the content of K.sub.2O is preferably 0 to 5%.
If the content of K.sub.2O is more than 5% in glass, the thermal
stability of the glass may be liable to deteriorate.
[0078] MgO is a component that enhances the thermal stability of
glass and the content of MgO is preferably 0 to 15%. If the content
of MgO is more than 15% in glass powder, the softening point of the
glass powder may improperly rise and it may become difficult to
perform laser welding with a desired laser output.
[0079] BaO is a component that enhances the thermal stability of
glass and the content of BaO is preferably 0 to 10%. If the content
of BaO is more than 10% in glass, the balance of the components in
the composition of the glass may be impaired, and the glass may be
liable to denitrify to the worse.
[0080] F.sub.2 is a component that contributes to lowering melting
point of glass and the content of F.sub.2 is preferably 0 to 5%. If
the content of F.sub.2 is more than 5% in glass, the thermal
stability of the glass may be liable to deteriorate.
[0081] In view of providing thermal stability and low-melting-point
characteristic, the total content of In.sub.2O.sub.3,
Ta.sub.2O.sub.5, La.sub.2O.sub.3, MoO.sub.3, WO.sub.3, Li.sub.2O,
Na.sub.2O, K.sub.2O, MgO, BaO, and F.sub.2 is preferably 10% or
less.
[0082] In addition to the above-mentioned components, other
components (such as CaO and SrO) can be added, for example, up to
10%.
[0083] It should be noted that, from the standpoint of reducing the
batch cost of the SnO-containing glass powder, the content of
transition metal oxides in the SnO-containing glass powder is
preferably 10% or less, more preferably 5% or less, particularly
preferably substantially zero. Herein, the phrase "substantially
zero" refers to a case where the content of transition metal oxides
in a glass composition is 3000 ppm (by mass) or less, preferably
1000 ppm (by mass) or less.
[0084] In addition, it is preferred that the SnO-containing glass
powder be substantially free of PbO from an environmental
standpoint. Herein, the phrase "substantially free of PbO" refers
to a case where the content of PbO in the glass composition is 1000
ppm (by mass) or less.
[0085] On the other hand, it is preferred to use, as the pigment,
an inorganic pigment, it is more preferred to use one kind or two
or more kinds selected from carbon, Co.sub.3O.sub.4, CuO,
Cr.sub.2O.sub.3, Fe.sub.2O.sub.3, MnO.sub.2, SnO, and
Ti.sub.nO.sub.2n-1 (n represents an integer), and it is
particularly preferred to use carbon. These pigments have excellent
chromogenic property and absorb laser light well.
[0086] The pigment is preferably substantially free of Cr-based
oxides from an environmental standpoint. Herein, the phrase
"substantially free of Cr-based oxides" refers to a case where the
content of Cr-based oxides in a pigment is 1000 ppm (by mass) or
less.
[0087] The average particle diameter D.sub.50 of the pigment is
preferably 0.1 to 3 .mu.m, particularly preferably 0.3 to 1 .mu.m.
Further, the maximum particle diameter D.sub.max of the pigment is
preferably 0.5 to 10 .mu.m, particularly preferably 1 to 5 .mu.m.
If the particle size of the pigment is too large, the particles of
the pigment may not easily disperse uniformly in the glass frit 5,
and glass may not soften and flow locally at the time of laser
welding. If the particle size of the pigment is too small,
particles of the pigment easily aggregate to each other as well,
and hence glass may also not soften and flow locally at the time of
laser welding. The average particle diameter D.sub.50 of primary
particles of the pigment is preferably 1 to 5000 nm, 3 to 1000 nm,
5 to 500 nm, particularly preferably 10 to 100 nm. If the size of
the primary particles of the pigment is too small, particles of the
pigment easily aggregate to each other, and hence it may become
difficult to disperse the pigment uniformly in the glass frit 5.
Therefore, there is a possibility in that the glass frit 5 may not
soften and flow locally at the time of laser sealing. On the other
hand, if the size of the primary particles of the pigment is too
large, it may become difficult to disperse the pigment uniformly in
the glass frit 5 as well, and hence the glass frit 5 may not soften
and flow locally at the time of laser sealing.
[0088] Further, the inorganic powder comprising the SnO-containing
glass powder preferably comprises a refractory filler. With this,
the thermal expansion coefficient of the glass frit 5 can be
reduced and the mechanical strength of the glass frit 5 can be
enhanced. The mixing ratio of the SnO-containing glass powder to
the refractory filler in the inorganic powder is, in terms of vol
%, preferably 40 to 100%:0 to 60%, particularly preferably 50 to
90%:10 to 50%. If the content of the refractory filler is more than
60 vol %, the ratio of the SnO-containing glass powder becomes
relatively small and the efficiency of laser welding may be liable
to deteriorate.
[0089] As the refractory filler, there may be used zircon,
zirconia, tin oxide, quartz, .beta.-spodumene, cordierite, mullite,
quartz glass, .beta.-eucryptite, .beta.-quartz, zirconium
phosphate, zirconium phosphate tungstate, zirconium tungstate, a
compound having a basic structure of [AB.sub.2 (MO.sub.4).sub.3]
such as NbZr(PO.sub.4).sub.3, where A represents Li, Na, K, Mg, Ca,
Sr, Ba, Zn, Cu, Ni, Mn, or the like, B represents Zr, Ti, Sn, Nb,
Al, Sc, Y, or the like, and M represents P, Si, W, Mo, or the like,
and a solid solution thereof.
[0090] The maximum particle diameter D.sub.max of the refractory
filler is preferably 30 .mu.m or less, more preferably 20 .mu.m or
less, particularly preferably 10 .mu.m or less. If the maximum
particle diameter D.sub.max of the refractory filler is more than
30 .mu.m, some parts of welding portions of glass frit 5 are liable
to have a thickness of 30 .mu.m or more, and hence the gap between
the element substrate 3 and the sealing substrate 4 may become
non-uniform in the OLED element package 1, and consequently, it may
become difficult to reduce the thickness of the OLED element
package 1, that is the OLED display device. Further, when the
maximum particle diameter D.sub.max of the refractory filler is
restricted to 30 .mu.m or less, the gap between the element
substrate 3 and the sealing substrate 4 can be easily narrowed.
Accordingly, a time necessary for performing laser welding is
shortened, and cracks and the like do not easily occur in a welding
portion of the glass frit 5 even if there is a difference in
thermal expansion coefficient between each of the element substrate
3 and the sealing substrate 4 and the glass frit 5.
[0091] The softening point of the glass frit 5 is preferably
450.degree. C. or less, more preferably 420.degree. C. or less,
particularly preferably 400.degree. C. or less. If the softening
point of the glass frit 5 is more than 450.degree. C., the
efficiency of laser welding may be liable to deteriorate. The lower
limit of the softening point of the glass frit 5 is not
particularly limited, but in view of the thermal stability of
glass, the softening point is preferably controlled to 300.degree.
C. or more. Herein, the term "softening point" refers to a value
measured under a nitrogen atmosphere with a macro-type differential
thermal analysis (DTA) apparatus, and in the DTA, the measurement
starts from room temperature and the temperature increase rate is
set to 10.degree. C./min. It should be noted that the softening
point measured with the macro-type DTA apparatus refers to a
temperature (Ts) at a fourth inflection point illustrated in FIG.
10.
[0092] At present, an active matrix drive system, in which an
active element such as a TFT is arranged at each pixel for driving,
is adopted as a drive system in an OLED display. In this case,
alkali-free glass (such as OA-10G manufactured by Nippon Electric
Glass Co., Ltd.) is used for glass substrates for the OLED display.
The thermal expansion coefficient of alkali-free glass is usually
40.times.10.sup.-7/.degree. C. or less. On the other hand, the
thermal expansion coefficient of a glass frit is 76 to
83.times.10.sup.-7/.degree. C. in many cases. Thus, it was
difficult to match the thermal expansion coefficient of a glass
frit strictly to the thermal expansion coefficient of alkali-free
glass. In contrast, the above-mentioned SnO-containing glass powder
has good compatibility with a low-expansion refractory filler, in
particular, NbZr(PO.sub.4).sub.3 and zirconium phosphate.
Therefore, the thermal expansion coefficient of the glass frit 5
can be remarkably reduced. Thus, when such refractory filler is
used, the thermal expansion coefficient of the glass frit 5 can be
easily controlled to 75.times.10.sup.-7/.degree. C. or less. In
this case, the thermal expansion coefficient of the glass frit 5 is
more preferably 65.times.10.sup.-7/.degree. C. or less, more
preferably 55.times.10.sup.-7/.degree. C. or less, particularly
preferably 49.times.10.sup.-7/.degree. C. or less. With this, the
stress on the welding portion of the glass frit 5 becomes smaller
to prevent the occurrence of stress destruction at the welding
portion. Herein, the term "thermal expansion coefficient" refers to
an average value of values each measured with a push-rod-type
thermal expansion coefficient measurement (TMA) apparatus in the
temperature range of 30 to 250.degree. C.
[0093] Next, a process of manufacturing the OLED element package 1
configured as described above is described.
[0094] First, the glass frit 5 in a paste form is applied onto the
peripheral portion of the sealing substrate 4 at a thickness of,
for example, 15 .mu.m and is then preliminarily fired so as to be
temporarily cured on the sealing substrate 4.
[0095] On the other hand, on the element substrate 3, after the
first electrode 6 is formed in a predetermined pattern at a
thickness of, for example, 300 nm, the OLED layer 2 is formed.
Then, the second electrode 7 is formed thereon in a predetermined
pattern. Further, in the peripheral portion of the element
substrate 3, SiO.sub.2 films (low-refractive index layers), each
having a thickness of 139 nm, and Si.sub.3N.sub.4 films
(high-refractive index layers), each having a thickness of 100.6
nm, are alternately formed over the electrodes 6 and 7 so that the
number of layers is nine in total, thereby forming the multilayer
dielectric film 8. It should be noted that the multilayer
dielectric film 8 is formed by alternately laminating the
low-refractive index layers and the high-refractive index layers
by, for example, a CVD method, a sputtering method, or a vacuum
deposition method.
[0096] Thereafter, the element substrate 3 and the sealing
substrate 4 are provided opposite to each other, and the glass frit
5 and the multilayer dielectric film 8 are brought into contact
with each other. Then, laser light is applied from the sealing
substrate 4 side to the glass frit 5 to melt the glass frit 5 so as
to directly weld the glass frit 5 and the multilayer dielectric
film 8. With this, the outer peripheral portions of the element
substrate 3 and the sealing substrate 4 are joined over the entire
periphery. As a result, the OLED layer 2 is hermetically
sealed.
[0097] In addition, with the OLED element package 1 configured as
described above, the following functions and effects are
enjoyed.
[0098] Specifically, each of the dielectric layers constituting the
multilayer dielectric film 8 can well maintain an adhesive force to
the glass frit 5 as compared with a metal layer. Therefore, even
without additionally providing a layer in addition to the
multilayer dielectric film 8 only for the purpose of enhancing the
adhesive force to the glass frit 5, the adhesive force to the glass
frit 5 can be well maintained. Moreover, each of the dielectric
layers constituting the multilayer dielectric film 8 does not have
conductivity. Therefore, even without additionally providing
another insulating layer, electric insulation from the electrodes 6
and 7 connected to the OLED layer 2 can be maintained. Thus,
additionally providing an improvement layer for improving the
adhesive force to the glass frit 5 or another insulating layer is
not an indispensable condition. Accordingly, the degree of freedom
in the design of the OLED element package 1 can be ensured.
[0099] Moreover, with the multilayer dielectric film 8 as described
above, an excellent reflectance can be easily realized in the
wavelength band of the laser light emitted from the laser L by
selecting a material and adjusting a thickness for each of the
low-refractive index dielectric layers and the high-refractive
index dielectric layers. Thus, when the laser light is applied from
the sealing substrate 4 side to the glass frit 5 at the time of
welding of the glass frit 5, the laser light is reliably reflected
at the multilayer dielectric film 8 to the glass frit 5 side so as
to be effectively used to heat the glass frit 5. Therefore, the
laser light transmitted through the multilayer dielectric film 8 to
be applied to the electrodes 6 and 7 is reduced as much as
possible. Accordingly, it is possible to reliably prevent a
situation in which the electrodes 6 and 7 and the OLED layer 2 are
unduly heated by the laser light to be thermally damaged.
[0100] It should be noted that the first aspect of the present
invention is not limited to the embodiment described above and can
be carried out in various modes. For example, although the case
where the multilayer dielectric film 8 is formed directly on the
electrodes 6 and 7 has been described in the above embodiment, an
insulating layer may be provided therebetween. Similarly, although
the case where the multilayer dielectric film 8 is welded directly
to the glass frit 5 has been described, an intermediate layer may
be provided between the multilayer dielectric film 8 and the glass
frit 5.
[0101] Further, although the transparent electrode made of ITO and
the metal electrode made of Al have been exemplified as the first
electrode 6 and the second electrode 7 in the embodiment described
above, other transparent electrodes made of IZO, AZO, and the like,
and other metal electrodes made of Ti, Ag, Cu, Cr, Mo, and the like
may also be used.
[0102] Further, although the OLED element package (OLED display
device) has been described as an example in the embodiment
described above, the first aspect of the present invention is
similarly applicable to an electrical element package used for
other devices such as an OLED lighting device or a solar cell.
[0103] Further, various types of glass frits other than the one
exemplified above can be used. Specifically, for example, a glass
frit containing V.sub.2O.sub.5-containing glass powder and
.beta.-eucryptite or zirconium phosphate tungstate or a glass frit
containing Bi.sub.2O.sub.3-containing glass powder and cordierite
or willemite may be used.
[0104] Next, an embodiment of the second aspect of the present
invention is described referring to the drawings. It should be
noted that, an OLED element package to be incorporated into an OLED
display device is described below as an example of an electrical
element package.
[0105] FIG. 3 is a longitudinal sectional view illustrating a
schematic configuration of an OLED element package according to
this embodiment. An OLED element package 1 comprises, as a basic
configuration, an element substrate 3 on which an OLED layer 2 is
formed, a sealing substrate 4 provided at a distance from a surface
of the element substrate 3 on the OLED layer 2 side so as to be
opposed to the element substrate 3, and a glass frit 5 for
surrounding the OLED layer 2 in a frame-like fashion so as to
hermetically seal a gap between the element substrate 3 and the
sealing substrate 4.
[0106] Each of the element substrate 3 and the sealing substrate 4
is formed of a glass substrate having a thickness of, for example,
0.05 to 2 mm in this embodiment. It should be noted that, in some
cases, a cavity having a given depth is formed on the sealing
substrate 4 so as to avoid contact with the OLED layer 2 or to
provide a hygroscopic material therein.
[0107] A first electrode 6 and a second electrode 7, which are
respectively connected to a back side and a front side of the OLED
layer 2, are provided on the element substrate 3. The electrodes 6
and 7 pass below the glass frit 5 to be guided from the OLED layer
2 to the exterior of the OLED element package 1 so as to supply
electric power to the OLED layer 2. It should be noted that the
electrodes 6 and 7 branch according to a predetermined pattern, as
illustrated in FIG. 4. Further, the first electrode 6 on the back
surface side of the OLED layer 2 is formed of, for example, a
transparent electrode film (ITO film), whereas the second electrode
7 on the front surface side of the OLED layer 2 is formed of, for
example, a metal electrode film such as aluminum. It should be
noted that the first electrode 6 and the second electrode 7 may
both be formed of a transparent electrode film.
[0108] Then, as illustrated in FIGS. 3 and 4, laser light emitted
from a laser L is applied from the sealing substrate 4 side to the
glass frit 5 to heat the glass frit 5 so that the glass frit
softens and flows to weld the element substrate 3 and the sealing
substrate 4. With this, a hermetically-sealed structure of the OLED
element package 1 is formed. It should be noted that, as the laser
L, for example, a near-infrared semiconductor laser (having a
wavelength of 800 to 1100 nm) is used.
[0109] If the electrodes 6 and 7 are heated at the time of the
laser welding of the glass frit 5, there is a possibility of
thermally damaging the electrodes 6 and 7. Moreover, there is
another possibility of transmitting the heat through the electrodes
6 and 7 to the OLED layer 2 to thermally damage the OLED layer 2.
Therefore, in this embodiment, a metal oxide film 9 functioning as
a protective film is provided between the glass frit 5 and each of
the electrodes 6 and 7 so as to protect the electrodes 6 and 7 from
laser light.
[0110] The metal oxide film 9 functioning as the protective layer
is preferably excellent in adhesiveness to the glass frit 5 and the
electrodes 6 and 7 and exhibits insulating property. As a material
thereof, SiO.sub.2, ZrO.sub.2, Y.sub.2O.sub.3, TiO.sub.2,
Al.sub.2O.sub.3, Ta.sub.2O.sub.5, and Nb.sub.2O.sub.5 can be
given.
[0111] The thickness of the metal oxide film 9 is preferably to 500
nm, 10 to 300 nm, particularly preferably 30 to 300 nm. If the
thickness of the metal oxide film 9 is less than 5 nm, the effect
of protecting the electrodes 6 and 7 is lowered. On the other hand,
when the thickness is more than 500 nm, the amount of a stress due
to a difference in thermal expansion between the glass frit 5 and
the metal oxide film 9 becomes large. As a result, separation is
liable to occur between the glass frit 5 and the metal oxide film 9
after the laser welding. Moreover, the thickness becomes a factor
of increasing the manufacturing cost of the electrical element
package.
[0112] The glass frit 5 is suitable to contain 80 to 99.95 mass %
of inorganic powder comprising SnO-containing glass powder and 0.05
to 20 mass % of pigment. In this case, the content of the inorganic
powder is preferably 90 to 99.95 mass %, 95 to 99.95 mass %,
particularly preferably 99 to 99.95 mass %. If the content of the
inorganic powder is small, the glass frit 5 does not soften and
flow sufficiently at the time of laser welding, and becomes
difficult to increase a welding strength. On the other hand, when
the content of the inorganic powder is more than 99.95 mass %, the
content of the pigment becomes relatively small, and hence the
laser-light absorption performance of the glass frit 5 is
lowered.
[0113] Moreover, when the content of the pigment is controlled to
0.05 mass % or more, the glass frit becomes more likely to absorb
the laser light, and hence the efficiency of laser welding is
improved to easily prevent the electrodes and the electrical
element from being thermally damaged. On the other hand, when the
content of the pigment is restricted to 20 mass % or less, it
becomes easy to prevent a situation in which the glass frit
devitrifies at the time of laser welding.
[0114] Preferred aspects of the average particle diameter D.sub.50,
the maximum particle diameter D.sub.max, and the glass composition
of the SnO-containing glass powder are the same as those described
above, and therefore the detailed description thereof is omitted
for convenience.
[0115] It is preferred to set the softening point of the
SnO-containing glass powder to the same as the softening point
described above.
[0116] The pigment is preferably an inorganic pigment, more
preferably is one kind or two or more kinds selected from carbon,
Co.sub.3O.sub.4, CuO, Cr.sub.2O.sub.3, Fe.sub.2O.sub.3, MnO.sub.2,
SnO, Ti.sub.nO.sub.2n-1 (n represents an integer), particularly
preferably carbon. As the carbon, amorphous carbon and graphite are
preferred. These pigments are excellent in chromogenic property and
have satisfactory laser-light absorption performance. It is
preferred to set the average particle diameter D.sub.50 of the
pigment and the average particle diameter D.sub.50 of the primary
particles of the pigment to the same values as those described
above. In addition, from an environmental point of view, the
pigment is preferably substantially free of a Cr-based oxide.
[0117] The glass frit 5 preferably further comprises a refractory
filler. With this, the thermal expansion coefficient of the glass
frit 5 can be lowered, while the mechanical strength of the glass
frit 5 can be enhanced. A mixing ratio of the SnO-containing glass
powder to the refractory filler in the inorganic powder is
preferably adjusted to the same as that described above.
[0118] Preferred aspects of the material and the maximum particle
diameter D.sub.max of the refractory filler are the same as those
described above.
[0119] A preferred range of the thermal expansion coefficient of
the glass frit 5 is the same as that described above.
[0120] The glass frit 5 and a vehicle are preferably kneaded and
processed into a paste material to be used. With this, application
workability and the like can be enhanced. It should be noted that
the vehicle usually contains a resin binder and a solvent. The same
resin binder and solvent as those described above are preferred,
and the detailed description thereof is omitted for
convenience.
[0121] Separation of the binder from the paste is preferably
carried out in an inert atmosphere, particularly in an N.sub.2
atmosphere. With this, it becomes easy to prevent a situation in
which the SnO-containing glass powder deteriorates at the time of
separation.
[0122] Further, the paste is preferably subjected to laser welding
in an inert atmosphere, particularly in an N.sub.2 atmosphere. With
this, it becomes easy to prevent a situation in which the
SnO-containing glass powder deteriorates at the time of laser
welding.
[0123] Next, a process of manufacturing the OLED element package 1
is described.
[0124] First, the glass frit 5 in a paste form is applied to the
peripheral portion of the sealing substrate 4 at a thickness of
about 40 .mu.m and a width of about 0.6 mm by, for example, a
screen printer, and is then dried and fired to decompose and
volatilize a resin component and a solvent component in the paste.
Thereafter, the glass frit is caused to soften and flow so as to
firmly adhere to the sealing substrate 4. A thickness of the glass
frit 5 after being fired is, for example, about 15 .mu.m. In order
to enhance the precision of the laser welding, a surface of the
glass frit after being fired is required to be smoothed.
Specifically, it is preferred to set surface roughness, the Ra
value and the RMS value to 0.7 .mu.m or less and, to 1 .mu.m or
less, respectively.
[0125] On the other hand, on the element substrate 3, after the
first electrode 6 is formed in a predetermined pattern at a
thickness of, for example, 150 nm, the SiO.sub.2 film 9 is formed
at a thickness of, for example, 100 nm on a region to be opposed to
the peripheral portion of the sealing substrate 4 where the glass
frit 5 has been printed and fired. It should be noted that the
SiO.sub.2 film 9 is formed by, for example, a CVD method, a
sputtering method, or a vacuum deposition method. Thereafter, the
OLED layer 2 is formed. Then, the second electrode 7 is formed
thereon in a predetermined pattern.
[0126] Subsequently, the element substrate 3 and the sealing
substrate 4 are provided so as to be opposed to each other so that
the glass frit 5 and the SiO.sub.2 film 9 are brought into contact
with each other. Then, laser light is applied from the sealing
substrate 4 side to the glass frit 5 so that the glass frit 5 is
melted to soften and flow to directly weld the glass frit 5 and the
SiO.sub.2 film 9. With this, the outer peripheral portions of the
element substrate 3 and the sealing substrate 4 are joined over the
entire periphery. As a result, the OLED layer 2 is hermetically
sealed.
[0127] It should be noted that the second aspect of the present
invention is not limited to the embodiment described above and can
be carried out in various modes. For example, although the case
where the SiO.sub.2 film 9 is formed directly on the first
electrode 6 has been described in the embodiment described above,
the film may be provided on the glass frit 5 on the sealing
substrate 4 side.
[0128] Further, although the transparent electrode made of ITO and
the metal electrode made of Al have been exemplified as the first
electrode 6 and the second electrode 7 in the embodiment described
above, other transparent electrodes made of IZO, AZO, FTO, ZnO, and
the like, and other metal electrodes made of Ti, Ag, Cu, Cr, Mo,
multilayer films thereof, and the like may also be used.
[0129] Further, although the OLED element package (OLED display
device) has been described as an example in the embodiment
described above, the second aspect of the present invention is
similarly applicable to an electrical element package used for
other devices such as an OLED lighting device or a solar cell.
[0130] Further, various types of glass frits other than the one
exemplified above can be used. Specifically, for example, a glass
frit containing V.sub.2O.sub.5-containing glass powder and
.beta.-eucryptite or a glass frit containing
Bi.sub.2O.sub.3-containing glass powder and cordierite or willemite
may be used.
Example 1
[0131] First, the first aspect of the present invention is
described in detail based on examples. It should be noted that the
first aspect of the present invention is not limited to the
following examples. The following examples are mere
exemplifications.
[0132] (Simulation of Frequency Characteristic of Reflectance)
[0133] Design values of film configurations of examples (No. 2 to
No. 4) of the multilayer dielectric film used for the electrical
element package according to the first aspect of the present
invention are shown in Table 1. It should be noted that, in Table
1, a single-layer dielectric film is shown as a comparative example
(No. 1).
TABLE-US-00001 TABLE 1 No. 1 No. 2 No. 3 No. 4 No. 5 First layer
Si.sub.3N.sub.4 Si.sub.3N.sub.4 Si.sub.3N.sub.4 Si.sub.3N.sub.4
Si.sub.3N.sub.4 (Thickness (nm)) (100.6) (100.6) (100.6) (100.6)
(100.6) Second layer -- SiO.sub.2 SiO.sub.2 SiO.sub.2 SiO.sub.2
(Thickness (nm)) (139.0) (139.0) (139.0) (139.0) Third layer --
Si.sub.3N.sub.4 Si.sub.3N.sub.4 Si.sub.3N.sub.4 Si.sub.3N.sub.4
(Thickness (nm)) (100.6) (100.6) (100.6) (100.6) Fourth layer -- --
SiO.sub.2 SiO.sub.2 SiO.sub.2 (Thickness (nm)) (139.0) (139.0)
(139.0) Fifth layer -- -- Si.sub.3N.sub.4 Si.sub.3N.sub.4
Si.sub.3N.sub.4 (Thickness (nm)) (100.6) (100.6) (100.6) Sixth
layer -- -- -- SiO.sub.2 SiO.sub.2 (Thickness (nm)) (139.0) (139.0)
Seventh layer -- -- -- Si.sub.3N.sub.4 Si.sub.3N.sub.4 (Thickness
(nm)) (100.6) (100.6) Eighth layer -- -- -- -- SiO.sub.2 (Thickness
(nm)) (139.0) Ninth layer -- -- -- -- Si.sub.3N.sub.4 (Thickness
(nm)) (100.6) Total thickness 100.6 340.1 579.7 819.2 1058.8
(nm)
[0134] Although being based on the simulation, the multilayer
dielectric films having the film configurations as shown in Table 1
exhibited wavelength characteristics of the reflectance as shown in
FIG. 5. As shown in FIG. 5, as compared with the comparative
example (No. 1) with single layer configuration, the wavelength
characteristic of the reflectance became better as the number of
layers increases. In the example (No. 5) with nine layers
configuration, the maximum reflectance reached even about 90%. In
addition, with the design of the examples (No. 2 to No. 5), the
reflectance to infrared laser light having a wavelength of 808 nm
became maximum.
Example 2
[0135] (Measured Values of Frequency Characteristic of
Reflectance)
[0136] Examples of film configurations of examples (No. 6 to No. 8)
of the multilayer dielectric film used for the electrical element
package according to the first aspect of the present invention are
shown in Table 2.
TABLE-US-00002 TABLE 2 No. 6 No. 7 No. 8 First layer
Si.sub.3N.sub.4 Si.sub.3N.sub.4 Si.sub.3N.sub.4 (Thickness (nm))
(100.6) (100.6) (100.6) Second layer SiO.sub.2 SiO.sub.2 SiO.sub.2
(Thickness (nm)) (139.0) (139.0) (139.0) Third layer --
Si.sub.3N.sub.4 Si.sub.3N.sub.4 (Thickness (nm)) (100.6) (100.6)
Fourth layer -- SiO.sub.2 SiO.sub.2 (Thickness (nm)) (139.0)
(139.0) Fifth layer -- Si.sub.3N.sub.4 Si.sub.3N.sub.4 (Thickness
(nm)) (100.6) (100.6) Sixth layer -- SiO.sub.2 SiO.sub.2 (Thickness
(nm)) (139.0) (139.0) Seventh layer -- -- Si.sub.3N.sub.4
(Thickness (nm)) (100.6) Eighth layer -- -- SiO.sub.2 (Thickness
(nm)) (139.0) Total thickness 239.6 718.8 958.4 (nm)
[0137] Frequency characteristics of the reflectance of the examples
(No. 6 to No. 8) are as shown in FIG. 6. Both the example with six
layers (No. 7) and the example with eight layers (No. 8) had the
maximum reflectance in the vicinity of the wavelength of 808 nm,
and about 70% of the maximum reflectance was realized with the
example with eight layers (No. 8).
Example 3
[0138] (Temperature Measurement of Electrodes at the Time of Laser
Welding)
[0139] The glass frit in a paste form was printed by screen
printing at a thickness of 15 .mu.m on the peripheral portion of
the glass substrate with a dimension of 40 mm in length by 50 mm in
width by 0.5 mm in thickness. Thereafter, preliminary firing was
performed at 500.degree. C. for one hour to temporarily cure the
glass frit, thereby manufacturing the sealing substrate.
[0140] In this case, the glass frit containing 99 mass % of the
inorganic powder and 1 mass % of the pigment was used. The
inorganic powder contained in the glass frit comprises 60 vol % of
SnO-based glass powder and 40 vol % of the refractory filler. The
SnO-based glass powder contains, as a glass composition in terms of
mol %, 59% of SnO, 20% of P.sub.2O.sub.5, 5% of ZnO, 15% of
B.sub.2O.sub.3, and 1% of Al.sub.2O.sub.3. Further, the glass
powder has an average particle diameter D.sub.50 of 2.5 .mu.m and a
maximum particle diameter D.sub.max of 7 .mu.m. The refractory
filler is made of zirconium phosphate powder, and has an average
particle diameter D.sub.50 of 2 .mu.m and a maximum particle
diameter D.sub.max of 8 .mu.m. On the other hand, the pigment
contained in the glass frit is made of carbon powder, and has an
average particle diameter D.sub.50 of 0.5 .mu.m and a maximum
particle diameter D.sub.max of 3 .mu.m.
[0141] On the other hand, the first electrode made of ITO was
formed and patterned at a thickness of 150 nm on the glass
substrate with a dimension of 40 mm in length by 50 mm in width by
0.5 mm in thickness. Thereafter, the OLED layer and the second
electrode made of Al were formed on the glass substrate by the
vacuum deposition method to manufacture the element substrate.
[0142] Thereafter, in a state in which the element substrate and
the sealing substrate were provided so as to be opposed to each
other under a nitrogen atmosphere, laser light having a wavelength
of 808 nm was applied from the sealing substrate side to weld the
glass frit to perform hermetic sealing. It should be noted that the
laser light was applied at an output of 20 W on the peripheral
portion of the glass substrate while being moved at 5 mm/s.
[0143] Then, temperatures of the first electrode and the second
electrode at the time of laser welding were measured by a radiation
thermometer. The temperature measurement at the time of laser
welding was first carried out for the first electrode made of ITO.
Specifically, the temperature measurement was carried out for:
[0144] (1) as a comparative example, the first electrode on which
the multilayer dielectric film was not provided (No. 9);
[0145] (2) as an example, the first electrode on which the
multilayer dielectric film with two layers in the same
configuration as that of the above-mentioned example (No. 6) was
provided (No. 10); and
[0146] (3) as an example, the first electrode on which the
multilayer dielectric film with eight layers in the same
configuration as that of the above-mentioned example (No. 8) was
provided (No. 11). The results are shown in FIG. 7.
[0147] As can be seen from FIG. 7, the temperature of the first
electrode (ITO) of the comparative example (No. 9) without the
multilayer dielectric film exceeded 400.degree. C., whereas the
temperatures of the first electrodes of the examples (No. 10 and
No. 11) on which the multilayer dielectric films are respectively
provided were below 400.degree. C. In particular, in the case of
the example (No. 11) using the multilayer dielectric film with
eight layers, the temperature of the second electrode dropped to
about 220.degree. C. Therefore, a sufficient effect of preventing
the first electrode from being thermally damaged can be
recognized.
[0148] Next, the temperature measurement at the time of laser
welding was carried out for the second electrode made of Al.
Specifically, the temperature measurement was carried out for:
[0149] (1) as a comparative example, the second electrode on which
the multilayer dielectric film was not provided (No. 12);
[0150] (2) as an example, the second electrode on which the
multilayer dielectric film with two layers in the same
configuration as that of the above-mentioned example (No. 6) was
provided (No. 13);
[0151] (3) as an example, the second electrode on which the
multilayer dielectric film with six layers in the same
configuration as that of the above-mentioned example (No. 7) was
provided (No. 14); and
[0152] (4) as an example, the second electrode on which the
multilayer dielectric film with eight layers in the same
configuration as that of the above-mentioned example (No. 8) was
provided (No. 15). The results are shown in FIG. 8.
[0153] As can be seen from FIG. 8, the temperature of the second
electrode (Al) of the comparative example (No. 12) without the
multilayer dielectric film rises to about 700.degree. C., whereas
the temperatures of the second electrodes of the examples (Nos. 13
to 15) on which the multilayer dielectric films were respectively
provided were below the above temperature. In particular, in the
cases of the example (No. 14) using the multilayer dielectric film
with six layers and the example (No. 15) using the multilayer
dielectric film with eight layers, the temperature of the second
electrode dropped to about 150.degree. C. Therefore, a sufficient
effect of preventing the second electrode from being thermally
damaged can be recognized.
Example 4
[0154] (Presence or Absence of Thermal Damage of Electrodes at the
Time of Laser Welding)
[0155] At the time of laser welding, laser light at an output of 12
W was applied on the peripheral portion of the glass substrate
while being moved at 3 mm/s to melt the glass frit. The presence or
absence of thermal damage of an electrode at this time was
inspected. Specifically, ITO was used as a material of the
electrode, and the inspection on the electrode was carried out
for:
[0156] (1) as a comparative example, the electrode on which the
multilayer dielectric film was not provided (No. 16);
[0157] (2) as an example, the electrode on which the multilayer
dielectric film with two layers in the same configuration as that
of the above-mentioned example (No. 6) was provided (No. 17);
and
[0158] (3) as an example, the electrode on which the multilayer
dielectric film with eight layers in the same configuration as that
of the above-mentioned example (No. 8) was provided (No. 18). It
should be noted that whether or not the electrode was thermally
damaged was determined based on the presence or absence of
conduction. Specifically, in the case where the electrode maintains
a conductive state, it is determined that thermal damage is
"absent". In the case where the electrode is in a non-conductive
state, it is determined that thermal damage is "present". This is
because, if the electrode is thermally damaged, the conductive path
is disconnected. The results are shown in Table 3.
TABLE-US-00003 TABLE 3 No. 16 No. 17 No. 18 Presence or absence of
thermal damage Present Absent Absent
[0159] Further, along with the inspection, temperatures of the frit
glass at the time of laser welding were inspected. The results are
shown in FIG. 9.
[0160] As shown in FIG. 9, as compared with a comparative example
without the multilayer dielectric film on the electrode (No. 16),
in the examples (Nos. 17 and 18) in which the multilayer dielectric
films were respectively provided on the electrodes, the
temperatures of the frit glass became high. Even based on such the
results, it can be recognized that the laser light was reflected by
the multilayer dielectric film to the frit glass side so that the
laser light is effectively used to heat the frit glass in the
examples (Nos. 17 and 18).
Example 5
[0161] Hereinafter, the second aspect of the present invention is
described in detail based on examples. It should be noted that the
following examples are mere exemplifications. The second aspect of
the present invention is not limited to the following examples.
[0162] Table 4 shows examples (Sample Nos. 1 to 4) and a
comparative example (Sample No. 5) of the second aspect of the
present invention.
TABLE-US-00004 TABLE 4 Comparative Examples Example No. 1 No. 2 No.
3 No. 4 No. 5 Protective film SiO.sub.2 SiO.sub.2 SiO.sub.2
SiO.sub.2 None Thickness (nm) 50 100 300 1000 Laser-light Glass
frit 730 750 740 750 740 irradiation average temperature (.degree.
C.) conditions A Resistance Before 80 80 80 80 80 Output: 22 W
value irradiation Speed: 25 mm/s (.OMEGA. cm) After 90 80 80 80 No
conduction Beam diameter: irradiation .phi.0.8 mm HAST test
.smallcircle. .smallcircle. .smallcircle. x .smallcircle.
Laser-light Glass frit 640 630 640 630 640 irradiation average
temperature (.degree. C.) conditions B Resistance Before 80 80 80
80 80 Output: 15 W value irradiation Speed: 10 mm/s (.OMEGA. cm)
After 80 80 80 80 120 Beam diameter: irradiation .phi.0.8 mm HAST
test .smallcircle. .smallcircle. .smallcircle. x .smallcircle.
Laser-light Glass frit 680 690 685 680 690 irradiation average
temperature (.degree. C.) conditions C Resistance Before 80 80 80
80 80 Output: 12 W value irradiation Speed: 3 mm/s (.OMEGA. cm)
After 85 85 80 80 No conduction Beam diameter: irradiation .phi.0.8
mm HAST test .smallcircle. .smallcircle. .smallcircle. x
.smallcircle.
[0163] First, the glass frit and a vehicle were kneaded so that a
viscosity became about 150 Pas (25.degree. C. and a shear rate of
4), and then further kneaded with a three-roll mill to obtain a
paste thereof.
[0164] Herein, the glass frit containing 99.75 mass % of the
inorganic powder and 0.25 mass % of the pigment was used. The
inorganic powder in the glass frit contained 60 vol % of SnO-based
glass powder and 40 vol % of the refractory filler. And the
SnO-based glass powder contained, as a glass composition in terms
of mol %, 59% of SnO, 20% of P.sub.2O.sub.5, 5% of ZnO, 15% of
B.sub.2O.sub.3, and 1% of Al.sub.2O.sub.3. Further, the glass
powder had an average particle diameter D.sub.50 of 2 .mu.m and a
maximum particle diameter D.sub.max of 5 .mu.m. The refractory
filler was made of zirconium phosphate powder, and had an average
particle diameter D.sub.50 of 1.5 .mu.m and a maximum particle
diameter D.sub.max of 3.5 .mu.m. The pigment contained in the glass
frit was made of carbon powder, and had an average particle
diameter D.sub.50 of primary particles of about 30 nm. A
polyethylene carbonate resin (MW: 129000) was used as a resin
component of the vehicle, whereas propylene carbonate was used as a
solvent component. It should be noted that a softening point of the
glass frit was 400.degree. C., and a thermal expansion coefficient
of the glass frit was 49.times.10.sup.-7/.degree. C. (measurement
temperature range of 30 to 300.degree. C.). Herein, the softening
point was a value measured with a DTA apparatus, whereas the
thermal expansion coefficient was a value measured with a TMA
apparatus.
[0165] Next, the glass frit in a paste form prepared as described
above was printed by screen printing on the peripheral portion of a
glass substrate (OA-10G manufactured by Nippon Electric Glass Co.,
Ltd.) with a dimension of 40 mm in length by 50 mm in width by 0.5
mm in thickness so that the glass frit had a thickness of about 30
.mu.m and a width of about 0.6 mm, followed by drying under the
conditions of 120.degree. C. for 30 minutes under an air
atmosphere. After that, the resultant was fired under the
conditions of 480.degree. C. for 10 minutes under a nitrogen
atmosphere to decompose and volatilize a resin component in the
paste and to cause the glass frit to firmly adhere to the glass
substrate, thereby preparing a sealing substrate. A thickness of
the glass frit after being fired was about 16 .mu.m. Surface
roughness of the glass frit after being fired was measured. The Ra
value was 0.5 .mu.m, and the RMS value was 0.8 .mu.m.
[0166] On the other hand, the first electrode made of ITO was
formed and pattered at a thickness of 150 nm on a glass substrate
(OA-10G manufactured by Nippon Electric Glass Co., Ltd.) with a
dimension of 50 mm in length by 50 mm in width by 0.5 mm in
thickness. Thereafter, the SiO.sub.2 film was formed at a thickness
of 50 nm, 100 nm, 300 nm, or 1000 nm in the region where the glass
frit was to adhere. The SiO.sub.2 film was formed at a width of
about 1 mm so as to prevent the glass frit and the ITO film from
coming in contact with each other. It should be noted that the
oxide film was not formed for Sample No. 5. Thereafter, the OLED
layer and the second electrode made of Al were formed on the glass
substrate by the vacuum deposition method to form the element
substrate.
[0167] Subsequently, in a state in which the sealing substrate and
the element substrate were provided so as to be opposed to each
other under the nitrogen atmosphere, laser light having a
wavelength of 808 nm was applied from the sealing substrate side
along the glass frit to weld the sealing substrate and the element
substrate. It should be noted that the laser-light irradiation
conditions were as described in the table.
[0168] Sample Nos. 1 to 5 were evaluated as follows.
[0169] The temperature of the glass frit at the time of irradiation
with laser light was measured by using the radiation
thermometer.
[0170] The electric resistance of the ITO film located immediately
below the glass frit was measured before and after the irradiation
with laser light so as to evaluate whether or not the ITO film
thermally deteriorated.
[0171] After a HAST test (highly accelerated temperature and
humidity stress test) was conducted for the glass frit which had
been subject to the laser welding, whether or not the separation of
the glass frit was observed. The glass frit without separation was
evaluated with Symbol "o", whereas the glass frit for which the
separation occurred was evaluated with Symbol "x". It should be
noted that the HAST test was conducted under the conditions of
121.degree. C., 100% RH, and 2 atm for 24 hours.
[0172] As is apparent from Table 4, no great change was observed in
the resistance value of the ITO film for Sample Nos. 1 to 4,
between before and after the irradiation of laser light. This fact
shows that the SiO.sub.2 film was able to properly protect the ITO
film to prevent the ITO film from thermally deteriorating due to
the irradiation of laser light. In particular, no unfavorable
situation such as separation was observed in Sample Nos. 1 to 3
after the HAST test. This fact shows that the glass frit and the
SiO.sub.2 film firmly adhered to each other.
[0173] On the other hand, in sample No. 5 without the SiO.sub.2
film, the resistance value of the ITO film increased after the
irradiation of laser light. In particular, under the laser-light
irradiation conditions A and C, the ITO film was thermally damaged
to a severe extent, and therefore it was impossible to measure the
resistance value of the ITO film.
REFERENCE SIGNS LIST
[0174] 1 OLED element package [0175] 2 OLED layer [0176] 3 element
substrate [0177] 4 sealing substrate [0178] 5 glass frit [0179] 6
first electrode [0180] 7 second electrode [0181] 8 multilayer
dielectric film [0182] 9 metal oxide film (SiO.sub.2 film) [0183] L
laser
* * * * *