U.S. patent application number 11/100977 was filed with the patent office on 2005-09-08 for process for manufacturing systems for conversion of water into hydrogen and sorption of hydrogen.
This patent application is currently assigned to SAES Getters S.p.A.. Invention is credited to Ferrario, Bruno, Gallitognotta, Alessandro, Tominetti, Stefano.
Application Number | 20050196527 11/100977 |
Document ID | / |
Family ID | 11448440 |
Filed Date | 2005-09-08 |
United States Patent
Application |
20050196527 |
Kind Code |
A1 |
Ferrario, Bruno ; et
al. |
September 8, 2005 |
Process for manufacturing systems for conversion of water into
hydrogen and sorption of hydrogen
Abstract
The invention teaches a system suitable for use in a
water-sensitive electronic device which comprises two superimposed
layers, the first material of which is formed of a material capable
of sorbing hydrogen, the second material formed of a material
capable of converting water into hydrogen; a screen of the type
with light-emitting organic diodes comprising the system according
to the invention.
Inventors: |
Ferrario, Bruno; (Rescaldina
(MI), IT) ; Tominetti, Stefano; (Milano, IT) ;
Gallitognotta, Alessandro; (Origgio (VA), IT) |
Correspondence
Address: |
PERKINS COIE LLP
P.O. BOX 2168
MENLO PARK
CA
94026
US
|
Assignee: |
SAES Getters S.p.A.
|
Family ID: |
11448440 |
Appl. No.: |
11/100977 |
Filed: |
April 6, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11100977 |
Apr 6, 2005 |
|
|
|
10256560 |
Sep 27, 2002 |
|
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Current U.S.
Class: |
427/66 ;
427/207.1; 427/256; 445/24 |
Current CPC
Class: |
Y10T 428/12792 20150115;
Y10T 428/12771 20150115; H01L 51/5259 20130101; Y10S 428/917
20130101; Y10T 428/12986 20150115; Y10T 428/12806 20150115; Y10T
156/10 20150115 |
Class at
Publication: |
427/066 ;
427/207.1; 427/256; 445/024 |
International
Class: |
B05D 005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 27, 2001 |
IT |
MI2001A2010 |
Claims
1-7. (canceled)
8. A process for manufacturing a system two superimposed layers
directly contacting each other, said first layer which is formed of
material capable of sorbing hydrogen, said second layer formed of a
material capable of converting water into hydrogen, comprising the
steps of: preparing a substrate; depositing on said substrate a
first layer of a material selected between hydrogen sorbing
material and material capable of converting water into hydrogen,
having also arranged on said substrate a masking element;
depositing a second layer of a material selected between hydrogen
sorbing material and material capable of converting water into
hydrogen wherein said second layer has a different function from
said material of the first layer.
9. The process according to claim 8 wherein said material of said
first layer is the hydrogen sorbing material.
10. The process according to claim 8 wherein said same masking
element used in said deposition of said first layer is used in said
step of depositing the second layer of material.
11. The process according to claim 8 wherein a second masking
element having different ports from those of said masking element
used in said deposition of said first layer, is used in said step
of depositing said second layer of material.
12. The process according to claim 11 wherein said second masking
element has ports of larger size than said masking element used for
said deposition of said first layer, such that said second layer
covers completely said first layer.
13. The process according to claim 8 wherein said substrate is one
of the two supports of a screen of the type with light-emitting
organic diodes.
14. The process according to claim 8 wherein said substrate is a
monoadhesive sheet.
15. The process according to claim 14 further comprising a step of
punching said monoadhesive sheet after the system according to
claim 8 has been deposited on said monoadhesive sheet.
16. The process according to claim 14 further comprising a step of
punching said monoadhesive sheet before the system according to
claim 8 is deposited on said monoadhesive sheet.
17. The process according to claim 8 wherein said substrate is a
biadhesive sheet.
18. The process according to claim 17, further comprising the steps
of: providing a biadhesive sheet comprising two sheets of
protective paper; incising one sheet of protective paper along the
edges of some portions thereof; removing said portions thus forming
cavities; filling to the top level said cavities with a first layer
of a material; arranging a masking element on said biadhesive
sheet, wherein said masking element having ports encompassing said
cavities filled to the top level; depositing a second layer of a
material; and removing said masking element.
19. The process according to claim 18, further comprising a step of
punching said biadhesive sheet while leaving integral said layer of
protective paper opposed to that on which said system has been
deposited, said punching made before the deposit of said first
layer of material or after removal of said masking element.
20. The process according to claim 17 further comprising the steps
of: providing a biadhesive sheet comprising two sheets of
protective paper; incising one sheet of protective paper along the
edges of some portions thereof; removing said portions thus forming
cavities; incising said sheet of protective paper along the
perimeter of portions encompassing said cavities; filling to the
top level said cavities with a first layer of a first material;
removing said paper covering said zones, so as to form openings
encompassing said first layer of material; arranging a second
masking element on said biadhesive sheet, said masking element
having ports coinciding with said openings; depositing a second
layer of a second material; and removing said masking element.
21. The process according to claim 20, further comprising a step of
punching said biadhesive sheet while leaving integral said layer of
protective paper opposed to that where said system is deposited,
said punching step being carried out before said deposition of said
first layer of material or after said removal of said masking
element.
22. A method comprising: providing an OLED support; forming a
hydrogen getter layer on the OLED support; forming a drier layer on
the hydrogen getter layer.
23. The method of claim 22 wherein the drier layer covers entirely
the hydrogen getter layer.
24. The method of claim 22 wherein the support includes an adhesive
sheet, and wherein the hydrogen getter layer and the drier layer
are formed on the adhesive sheet.
25. A method comprising: masking a support with a first masking
element having ports of a first size; depositing a first getter
layer on the support; masking the support with a second masking
element having ports of a second size, wherein the ports of a
second size have a larger port area than the ports of a first size;
depositing a second getter layer on the first getter layer.
26. The method of claim 25, wherein the first getter layer includes
a hydrogen getter material and the second getter layer includes a
drier material.
27. The method of claim 25 wherein the support includes an adhesive
sheet.
Description
REFERENCE TO PRIORITY DOCUMENTS
[0001] This application claims priority under 35 U.S.C. 119 to
Italian Application MI2001A2010, filed on Sep. 27, 2001, which is
incorporated by reference for all purposes.
BACKGROUND
[0002] It is generally known in the art that the functionality of
many electronic devices can be altered by the contact with water,
even if only present in traces. In semiconductor devices water can
oxidize the electric contacts or chemically alter some parts
thereof, or of laser amplifiers used in optical fiber
communications. This is described in EP-A-720260.
[0003] An electronic application of high industrial interest
wherein absence of water is requested are electroluminescent
screens based on the use of organic materials, is known in the
field as OLEDs (from "Organic Light Emitting Devices").
[0004] The structure of an OLED is formed of a first transparent,
essentially planar support, generally made of glass or of a plastic
polymer; a first series of transparent linear and mutually parallel
electrodes (generally having anode functionality), deposited on the
first support; a double layer of different electroluminescent
organic materials, of which the first layer is a conductor of
electronic vacancies (also defined "holes") and the second of
electrons, deposited on the first set of electrodes; a second
series of linear and mutually parallel electrodes (generally having
cathode functionality) that are orthogonally oriented with respect
to those of the first series, in contact with the upper side of the
double layer of organic materials, so that the latter is comprised
between both series of electrodes; and a second not necessarily
transparent support that may be made of glass, metal or plastics
and is substantially planar and parallel to the first support. The
two supports are secured to each other along their perimeter,
generally by glueing, so that the active part of the structure
(electrodes and electroluminescent organic materials) is in a
closed space. The first transparent support is the part where the
image is visualized, whereas the second support generally has only
the function of closing and backing the device, in order to confer
mechanical resistance thereto.
[0005] The anode is formed of a transparent conductive material,
generally a mixed oxide of indium and tin
(In.sub.2O.sub.3--SnO.sub.2) which has the features of a
semiconductor, known in the field with the acronym ITO (from
"Indium Tin Oxide"), whereas the cathode is formed of alkali-earth
metals, such as Ba, Ca, and Mg--Ag and Al--Li alloys. When a
potential difference is applied to the electrodes, the electrons
and the holes are conveyed to the organic material double layer and
combine leading to the formation of photons, whose wave length
depends on the nature of the organic material used.
[0006] For a description of the operating principles of OLEDs and
greater details on their structure one can refer to the abundant
literature of the field.
[0007] A problem encountered with the functioning of OLEDs is their
deterioration following to exposure to moisture, which can react
with the organic materials (generally polyunsaturated and therefore
rather reactive species), as well as with the cathode, formed of
particularly reactive metals. The portions concerned with these
reactions loose their light-emitting functionality, thus forming
black spots on the screen surface.
[0008] In order to overcome this problem, international publication
WO 99/03122 describes the introduction into the internal space of
an OLED of a gas reactive towards water, selected for example among
silanes, trimethylaluminum or triethylaluminum. These gases react
quickly with the water molecules subtracting them from the internal
space of the OLED and generating reaction products which are not
detrimental for the functioning of the device. The introduction of
a gas in an OLED during the production thereof is however difficult
to realize.
[0009] U.S. Pat. No. 5,882,761 teaches that the use of solid
materials which chemically fix water by remaining in the solid
state, such as for example calcium oxide (CaO). A possible problem
with the use of this kind of sorbers is that these materials are
generally in powder form, and therefore must be retained by a sheet
(for example a nonwoven fabric) permeable to water but able to
retain the powder particles. Due to the use of the powder material
and of the permeable sheet, the minimum thickness of the component
intended for water sorption cannot be lower than limit values of
about 0.3-0.4 mm, whereas OLEDs manufacturers, in order to fully
exploit the potentialities of these flat and thin screens, require
moisture sorbing systems which have lower thickness values than the
above mentioned ones. Another problem that does not allow the
decrease the tickness of the sorbing systems based on the use of
CaO or similar is the reduction of the water sorbing capacity.
[0010] International publication WO 98/59356 teaches the use of a
getter material arranged inside the OLED and fixed onto the second
support. This document indicates some alternatives to calcium oxide
for water sorption; in particular it indicates the possibility to
use materials such as barium, lithium, calcium, barium oxide or
similar.
[0011] In particular, the metals lithium, barium, and calcium,
being particularly reactive towards water, can be used in the
devices in limited quantities.
[0012] Said metals react with water according to the reaction:
[0013] 2M+2H.sub.2O.fwdarw.2M(OH)+H.sub.2 (wherein M: lithium)
[0014] M+2H.sub.2O.fwdarw.M(OH).sub.2+H.sub.2 (wherein M: barium
and calcium)
[0015] As it can be noted from the reaction stoichiometry, one or
two molecules of metal hydroxides and one molecule of hydrogen are
formed every two reacted water molecules. These metals are very
reactive, and a drawback is that hydrogen can collect in the OLED
thus building up a partial pressure inside the device which can
pose safety problems.
[0016] Although hydrogen diffuses through the glue used for fixing
the two supports of the device and therefore can move outwards, the
velocity of hydrogen formation can be higher than the hydrogen
permeation velocity through the OLED sealing, thus causing a
continuous increase of the gas quantity in the internal space of
the device.
BRIEF DESCRIPTION OF THE INVENTION
[0017] The present invention relates to systems for the conversion
of water into hydrogen and for hydrogen sorption in electronic
devices and to a process for manufacturing such systems. The
invention therefore provides a system for the combined removal of
water and hydrogen, to be used in water sensible devices, in a
preferred use, for screens containing electroluminescent organic
materials. In one embodiment, the system includes two superimposed
layers directly in contact with each other, one of which is formed
of a material capable of sorbing hydrogen, the other formed of a
material capable of converting water into hydrogen.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] These advantages and the features of the invention will
appear to those skilled in the art from the following detailed
description with reference to the accompanying drawings,
wherein:
[0019] FIG. 1 schematically shows in cross-section an OLED device
without a gas sorbing system;
[0020] FIG. 2 shows a support of an OLED device, whereon the system
according to a first embodiment of the invention;
[0021] FIG. 3 shows a support of an OLED device, whereon the system
according to the invention has been formed, in a alternate
embodiment of the invention;
[0022] FIG. 4 shows a support of an OLED device, whereon the system
according to the invention has been formed, in a second alternate
embodiment of the invention;
[0023] FIG. 5 schematically shows a possible manufacturing process
of the first embodiment;
[0024] FIG. 6 schematically shows a manufacturing process of the
second embodiment;
[0025] FIG. 7 schematically shows a first possible manufacturing
process of the third embodiment;
[0026] FIG. 8 schematically shows a second possible manufacturing
process of the third embodiment.
DETAILED DESCRIPTION OF THE INVENTION
[0027] As previously stated, the invention includes function of
removing traces of water and hydrogen from the internal space of
electronic devices. To this end, it includes a layer of material
capable of converting water into hydrogen and a layer of hydrogen
sorbing material which is deposited on a substrate.
[0028] Various hydrogen sorbing materials can be used in different
embodiments of the invention and include: titanium, zirconium,
titanium-zirconium alloys, alloys of titanium containing a weight
percentage of titanium not lower than 50%, zirconium alloys
containing a weight percentage of zirconium not lower than 50%.
Also, some unsaturated organic compounds coupled with traditional
hydrogenation catalysts can be used, which is described by
international publication WO 99/48125, which is incorporated by
reference. The use of unsaturated organic molecules of low
molecular weight provides significant advantage, such as for
example 1,4-bis(phenylethynylbenzene), coupled for example with
metallic palladium, since they can be easily deposited in thin
layers on substrates through evaporation.
[0029] The material for converting water into hydrogen is selected
in the group of the alkali or alkali-earth metals; although many
materials can be used barium is used in a preferred embodiment.
[0030] In the case of an OLED the layer facing the internal space
can be formed both of a hydrogen sorbing material and of a material
capable of converting water into hydrogen; preferably, it is formed
of the latter, so that in the following reference will be made to
such a configuration. Furthermore, the two layers are superimposed
and in contact with each other and can have the same or different
shape and size; preferably the external layer covers entirely the
internal one.
[0031] The substrates on which the system according to the
invention can be deposited are various: the layers can be deposited
directly on the OLED support facing the active element thereof, but
also on other substrates, such as monoadhesive or biadhesive
sheets.
[0032] Mono- and biadhesive sheets are well known and widely used
in a number of technological applications. These sheets or tapes
are generally formed of a support (a thin sheet of plastic
material) on one or both faces of which there is provided a layer
of adhesive material. For example, the support can be made in
polyethyleneterephtalate (PET), with thickness values within 4 and
20 micron (.mu.m), whereas the adhesive layers are made with
acrylic materials having thickness values of the order of the tens
of micron. Said adhesive sheets are sold by manufacturers with
sheets of paper having the function of protecting the adhesive from
contamination by external agents. Adhesive sheets or tapes of this
kind are commercially available for example by Japanese company
Nitto-Denko, with catalogue number HJ-3160W, or from Japanese
company Teraoka with catalogue number 707.
[0033] FIG. 1 shows the cross-section of an OLED device 10: on a
first transparent planar support 101 is present the active element
of the device formed of a first series 102 of transparent, linear
and mutually parallel electrodes, a double layer of
electroluminescent organic materials 103 conductors of electronic
vacancies (holes) and of electrons, and a second series 104 of
linear electrodes, mutually parallel and orthogonal to those of the
first series. A second support 105 planar and parallel to the first
support is fixed thereto by means of a glue, thus defining the
internal space 106.
[0034] FIG. 2 shows the support 105 of OLED 10, on which is
arranged the system according to the invention in a first
embodiment thereof. The system is formed of a layer 201 of material
capable of sorbing hydrogen, directly deposited on the surface of
the second support of the OLED and of a second layer 202 of a
material capable of converting water into hydrogen, deposited onto
the first layer.
[0035] Then, other embodiments are possible, which allow to obtain
the system of the invention independently of the final device, that
is, without involving elements of the latter during the preparation
of said system.
[0036] With this regard, the second embodiment of the invention is
to be considered, shown in FIG. 3, which uses as a substrate a
monoadhesive sheet: therein, the layer 304 of hydrogen sorbing
material and the layer 305 of material capable of converting water
into hydrogen have been deposited on a monoadhesive sheet 301,
formed of a support 302, an adhesive layer 303. Soon after
production, the system represented in FIG. 3 also comprises a
protective sheet of paper covering the adhesive layer, but this
protective sheet is removed before placing the system in contact
with support 105, and is thus not shown in the drawing.
[0037] The third embodiment of the invention is shown in FIG. 4;
therein, the layer 405 of hydrogen sorbing material and the layer
406 of material capable of converting water into hydrogen are
deposited on a biadhesive layer 401, formed of a support 402
covered on both sides with adhesive layers 403, 404 and with paper
sheets of which only some parts are shown in the figure.
[0038] An alternate use of the invention relates to manufacturing
processes of the system in some possible above described
embodiments.
[0039] The layer of hydrogen sorbing material can be deposited by
means of a suitable technique which allows to form thin films: in
the case of titanium and of the unsaturated organic compounds of
low molecular weight, evaporation can be used, while in the case of
the zirconium and of the alloys in general it is necessary to use
other techniques, such as Physical Vapor Deposition, also known as
PVD or "sputtering", which is well known in the art and does not
need to be described here.
[0040] The film of material capable of converting water into
hydrogen is deposited on this first layer: to this purpose various
evaporation techniques can be used, among which, in the specific
case of the barium, the technique based on the use of dispensers
formed of threads having a U-shaped cross-section, which are loaded
along the whole length thereof with an alloy of the metal.
[0041] These threads are connected to an electric current generator
and when this is activated, the threads are heated by Joule effect
thus reaching a temperature at which it is observed the formation
of vapors of barium, which is allowed to deposit onto the layer of
hydrogen sorbing material.
[0042] FIG. 5 shows the process for obtaining the first embodiment
shown in FIG. 2. Onto the OLED support 105 is positioned a first
masking element 501 having an opening 502 (FIG. 5a). Since said
openings are called in the field "ports", said term will be used in
the following. On element 501 is deposited, by means of one of the
above mentioned techniques, layer 201 of hydrogen sorbing material
(FIG. 5b). Subsequently, said masking element is removed and
substituted with a second masking element 503 having a port 504
suitable for encompassing layer 201 (FIG. 5c). The material capable
of converting water into hydrogen is then deposited on said second
masking element, thus forming layer 202 (FIG. 5d). Finally, the
second masking element is removed, leaving system 50 (FIG. 5e). In
case it is desired to obtain superimposed layers having the same
shape and size, it is not necessary to use a second masking step,
but it is possible to use a single masking element, having the
desired shape and size.
[0043] Because of the very high reactivity of the water converting
material it is essential that the system does not contact moisture
of the air; for this reason it must be protected both during the
production and subsequently, maintaining it in an inert
environment.
[0044] FIG. 6 schematically shows the process for obtaining the
second embodiment illustrated in FIG. 3: on the monoadhesive sheet
301 is positioned a masking element 601, provided with a port 602
on the surface thereof (FIG. 6a). Subsequently layer 304 of
hydrogen sorbing material is deposited (FIG. 6b). The used masking
element is then removed and replaced with a second masking element
603 having a port 604 suitable for encompassing completely layer
304 (FIG. 6c). Subsequently it is carried out the second
deposition, by evaporation, of the material capable of converting
water into hydrogen, thus forming layer 305 (FIG. 6d). The next
operation consists in removing said second masking element and
cutting the monoadhesive sheet around the perimeter of the system
thus obtaining th final system 60 (FIG. 6e).
[0045] Finally, in FIGS. 7 and 8 there are schematically shown two
possible manufacturing processes of the third embodiment of the
invention by using a biadhesive sheet as a substrate; in this case,
it is possible to deposit the layer of moisture sorbing material
through a step of filling to the top level, by using one of the two
layers of adhesive.
[0046] The process schematized in FIG. 7 consists in providing a
biadhesive sheet 401 and in incising one of the layers of paper 701
which cover it, so as to selectively remove a portion 702 thereof
and to leave uncovered the underlying adhesive 404: in this way a
"cavity" 703 with vertical walls having a height equal to the
thickness of the sheet of paper is obtained, and with the bottom
covered with adhesive (FIG. 7a). The same paper thus works as a
masking element for the next operation: said cavity is in fact
filled to the top with the hydrogen sorbing material 405 (FIG. 7b).
Then, a masking element 704 having a port 705 such as to encompass
the cavity filled to the top is superimposed to the biadhesive
(FIG. 7c) and the deposition of the material capable of converting
water into hydrogen is carried out, which takes place on the
masking element and on the cavity filled to the top with the
hydrogen sorbing material, thus forming a layer 406 (FIG. 7d). By
removing said masking element it is obtained, in correspondence of
the original cavity, system 70 according to the invention, which
can be isolated by cutting the biadhesive sheet around the
perimeter of said system (FIG. 7e).
[0047] The process of FIG. 8 involves the following steps: first,
one of the paper layers 701 of the biadhesive sheet 401 is incised
thus allowing the removal of one portion 801 and the formation of
the cavity 802 (FIG. 8a). Subsequently, the same paper layer is
incised again along the perimeter of a zone encompassing cavity 802
(FIG. 8b), thus defining a portion 803 of paper. Then, said cavity
is filled to the top with the hydrogen sorbing material thus
forming layer 405 (FIG. 8c); at this point portion 803 is removed,
leaving an opening 804 such as to encompass layer 405 of hydrogen
sorbing material (FIG. 8d). A masking element 805 having a port
coincident with said opening is laid onto the biadhesive (FIG. 8e)
and the material capable of converting water into hydrogen is
evaporated thereon thus forming layer 406 (FIG. 8f). The masking is
then removed and the biadhesive can be cut around the perimeter of
the double layer leaving system 80 (FIG. 8g).
[0048] The processes described in the case that mono- or biadhesive
sheet are used have been illustrated with reference to the
production of a single system, but, for reasons of productivity and
economicity, they can be realized continuously in a quick and
reproducible way. As a matter of fact, in the first case
continuously fed monoadhesive tapes can be used, whereon a double
masking is conducted in order to deposit selectively, by means of
evaporation, the moisture sorbing material and the barium layer so
as to form at the same time a number of systems. Subsequently the
single systems can be obtained by shearing or mechanical cut, or
alternatively, it is possible to carry out a punching step, by
cutting with suitable tools the monoadhesive sheet along the edges
of the different systems, but leaving the protective paper
integral. Continuous tapes can be obtained in this way, on which a
number of systems according to the invention are provided, which
can then be separated from time to time like adhesive labels.
[0049] The same result is obtained by carrying out the punching
step on the monoadhesive sheet before the deposition of the system
according to the invention. Two different processes can be carried
out in the case of the biadhesive sheet, as already observed. In
the first case the steps to be carried out are the following:
first, incision of one of the paper layers is carried out, defining
the portions whereon the systems according to the invention will be
formed, and the parts of paper over said portions are removed, thus
obtaining cavities with vertical walls having a height equal to the
thickness of the paper sheet, and with the bottom covered by
adhesive. Then, filling to the top of said cavities with the
hydrogen sorbing material is carried out. Subsequently, a second
masking is realized with a masking element having ports such as to
encompass the cavities filled to the top and evaporation of the
material capable of converting water into hydrogen is carried out;
when said evaporation is completed, the masking element is removed
and the step of cutting or punching is at last carried out. In the
last case, one obtains continuous tapes whereon a number of systems
according to the invention are present, which can then be separated
from time to time and applied to the supports of the final
devices.
[0050] On the contrary, in order to carry out the second process
the steps to be carried out are: first incision on one of the paper
layers in order to define the portions on which the systems
according to the invention will be formed, removal of the paper
parts on said portions with formation of cavities, second incision
along the perimeter of zones suitable for encompassing said
cavities. The subsequent steps consist in filling to the top level
the cavities with the material capable of sorbing hydrogen thus
forming the correspondent layers, in removing the paper covering
said zones encompassing the original cavities, in masking and
depositing the second layer of material capable of converting water
into hydrogen. After the removal of said masking the single systems
can be then obtained also in this case by shearing or mechanical
cut or punching.
[0051] As already observed in the case of the monoadhesive sheet,
the step of punching the biadhesive sheet can also be carried out
before the deposition of the system according to the invention.
* * * * *