USOO9627646B2
`
`(12)
`
`United States Patent
`Ellinger et al.
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 9,627,646 B2
`Apr. 18, 2017
`
`(54) METHOD FOR ENCAPSULATING AN
`ELECTRONIC ARRANGEMENT
`
`(75) Inventors: Jan Ellinger, Hamburg (DE); Thorsten
`Krawinkel, Hamburg (DE); Klaus
`Keite-Telgenbischer Hamburg (DE):
`Ania stainer. Hambur (DE)
`s
`ger,
`9.
`(73) Assignee: tesa SE, Norderstedt (DE)
`(*) Notice:
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 283 days.
`
`9, 1977 McWhorter
`4,051, 195 A
`4,125,665 A 1 1/1978 Bemmels et al.
`4,552,604 A 11/1985 Green
`4,985.499 A
`1/1991 Nishikawa et al.
`5,104,938 A
`4, 1992 Toyama et al.
`5,705,571 A *
`1, 1998 Tsiang et al. ................. 525,338
`6.294.270 B1* 9/2001 Clough ......................... 428,620
`7,645,507 B2
`1/2010 Vermunicht et al.
`2002/0188053 Al 12/2002 Zang et al.
`2004/0225.025 A1
`11/2004 Sullivan et al.
`(Continued)
`FOREIGN PATENT DOCUMENTS
`
`(21) Appl. No.: 12/549,767
`(22) Filed:
`Aug. 28, 2009
`
`CN
`CN
`
`1, 2006
`1715355A A
`2, 2008
`101.133134. A
`(Continued)
`
`Prior Publication Data
`
`OTHER PUBLICATIONS
`
`M.E. Gross, et al., “Ultrabarrier Protective Coatings for Atmo
`spherically Sensitive Thin-Film Electronic Devices'. Society of
`Vacuum Coaters, pp. 89-92, 2003.
`(Continued)
`
`Primary Examiner — Galen Hauth
`(74) Attorney, Agent, or Firm — Norris McLaughlin &
`Marcus, P.A.
`
`(57)
`
`ABSTRACT
`
`The present invention relates to a method for encapsulating
`an electronic arrangement against permeants, in which a
`pressure-sensitive adhesive composition based on vinylaro
`matic block copolymers is provided, and in which the
`pressure-sensitive adhesive composition is applied onto and/
`or around the regions of the electronic arrangement which
`are to be encapsulated.
`
`(65)
`
`(30)
`
`Mar. 18, 2010
`US 201O/OO68514 A1
`Foreign Application Priority Data
`
`Sep. 18, 2008 (DE) ........................ 10 2008 O47 964
`
`(51) Int. Cl.
`B32B 37/2
`HOIL 5/52
`C09J 153/02
`(52) U.S. Cl.
`CPC ........ HOIL 51/5246 (2013.01); C09J 153/02
`(2013.01); C09J 153/025 (2013.01); Y10T
`428/2835 (2015.01)
`
`(2006.01)
`(2006.01)
`(2006.01)
`
`(58) Field of Classification Search
`USPC ............................. 264/271.1, 272.11, 272.17
`See application file for complete search history.
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`7/1972 Korpman ............... 428,355 BL
`3,676.202 A *
`3, 1977 Bullard et al.
`4,010, 140 A
`4,024.312 A * 5/1977 Korpman ...................... 428,343
`
`22 Claims, 2 Drawing Sheets
`
`y 4
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`-----------------------------------------------------------------------------------------
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`5b.
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`US 9,627,646 B2
`Page 2
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`8/2005 Bamborough et al.
`2005/0182150 A1
`2005/0228.096 A1 10, 2005 Kirsten et al.
`2005/0287363 A1 12/2005 Ring et al.
`2005/0288436 Al 12/2005 Ring et al.
`2005/0288437 A1 12/2005 Ring et al.
`2006/010O299 A1
`5/2006 Malik et al. .................... 522/31
`2007/0092722 A1
`4/2007 Vermunicht et al.
`2007. O135552 A1
`6, 2007 Wrosch et al.
`Bargmann et al.
`2007/O 137775 A1
`6, 2007
`2007/0270553 A1 11/2007
`Bohm et al.
`2008. O139734 A1
`6, 2008
`Nakashima et al.
`2008/0214717 A1
`9, 2008
`Yao et al.
`2008/0249236 A1 10, 2008
`Nakashima et al.
`2008/0286571 A1 11, 2008
`Ichimura et al.
`Fujita et al. .................. 313,504
`2009/0026934 A1* 1/2009
`
`FOREIGN PATENT DOCUMENTS
`
`CN
`DE
`DE
`EP
`EP
`EP
`EP
`EP
`EP
`JP
`JP
`JP
`JP
`JP
`JP
`
`101.313044 A
`102004.031188 A1
`102004.031189 A1
`1311559 B1
`1674 432 A1
`1743 928 A1
`1857515 A2
`1900.771 A1
`19752.17 A2
`2000080339
`2000219860
`2003209421
`2004O22277
`2007 503478
`2OO752.3979
`
`11/2008
`1, 2006
`1, 2006
`5, 2003
`6, 2006
`1, 2007
`11/2007
`3, 2008
`10, 2008
`3, 2000
`8, 2000
`T 2003
`1, 2004
`2/2007
`8, 2007
`
`2007297503 A 11, 2007
`JP
`2008115383 A
`5, 2008
`JP
`2009520042 A
`5, 2009
`JP
`2009 127031 A
`6, 2009
`JP
`2009 1498.29 A
`T 2009
`JP
`2004.04858 A
`4/2004
`TW
`98.21287 A1
`5, 1998
`WO
`OOf 39.189 A1
`T 2000
`WO
`02/26908 A1
`4, 2002
`WO
`03/065470 A1
`8, 2003
`WO
`2006/095O15 A1
`9, 2006
`WO
`2007/087281 A1
`8/2007
`WO
`WO WO 2007087281 A1 * 8, 2007
`
`OTHER PUBLICATIONS
`
`A.G. Erlat et al., “Ultra-high Barrier Coatings on Polymer Sub
`stances for Flexible Optoelectronics: Water Vapor Transport and
`Measurement Systems', 47th Annual Technical Conference Pro
`ceedings—Society of Vacuum Coaters, pp. 654-659, 2004.
`P. Dufour, et al., Chemistry & Technology of UV & EB Formulation
`for Coatings, Inks & Paints, Markets and Curing Equipment, vol. 1,
`pp. 15-46, 1991.
`English Translation of Taiwanese Office Action for related Taiwan
`ese Patent Application No. 098.131177 mailed Jan. 3, 2014.
`English Translation of Taiwanese Office Action for related Taiwan
`ese Patent Application No. 098.131177 mailed Aug. 21, 2014.
`English Translation of Japanese Office Action for related Japanese
`Patent Application No. 2009-215102 mailed Aug. 6, 2014.
`English Translation of Japanese Office Action for related Japanese
`Patent Application No. 2009-215102 dated Dec. 18, 2014.
`English Translation of Taiwanese Office Action for related Taiwan
`ese Patent Application No. 098.131177 mailed Jun. 15, 2015.
`* cited by examiner
`
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`U.S. Patent
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`Apr. 18, 2017
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`Sheet 1 of 2
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`US 9,627,646 B2
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`'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
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`Fig. 1
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`U.S. Patent
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`Apr. 18, 2017
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`Sheet 2 of 2
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`US 9,627,646 B2
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`1.
`METHOD FOR ENCAPSULATING AN
`ELECTRONIC ARRANGEMENT
`
`US 9,627,646 B2
`
`2
`water vapour. In addition, there are a large number of further
`requirements for Such (opto)electronic arrangements. The
`flexible adhesive solutions are therefore intended not only to
`achieve a good adhesion between two Substrates, but addi
`tionally to fulfil properties such as high shear strength and
`peel strength, chemical resistance, ageing resistance, high
`transparency, simple processability and also high flexibility
`and pliability.
`One approach that is common according to the prior art is
`therefore to place the electronic arrangement between two
`Substrates that are impermeable to water vapour and oxygen.
`Afterwards, sealing is then effected at the edges. For inflex
`ible structures, glass or metal Substrates are used, which
`offer a high permeation barrier but are very susceptible to
`mechanical loading. Furthermore, these substrates cause the
`entire arrangement to have a relatively large thickness. In the
`case of metal Substrates, moreover, there is no transparency.
`For flexible arrangements, by contrast, use is made of planar
`Substrates. Such as transparent or non-transparent films,
`which can be embodied in multilayer fashion. Combinations
`of different polymers as well as inorganic or organic layers
`can be used in this case. The use of Such planar Substrates
`enables a flexible, extremely thin construction. In this case,
`a wide variety of substrates Such as e.g. films, woven fabrics,
`nonwovens and papers or combinations thereof are possible
`for the various applications.
`In order to achieve a best possible sealing, special barrier
`adhesive compositions are used. A good adhesive composi
`tion for the sealing of (opto)electronic components has a low
`permeability to oxygen and in particular to water vapour, has
`a sufficient adhesion on the arrangement and can flow well
`on the latter. A low adhesion on the arrangement reduces the
`barrier effect at the interface, thereby enabling oxygen and
`water vapour to enter independently of the properties of the
`adhesive composition. It is only if the contact between
`composition and Substrate is continuous that the properties
`of the composition are the determining factor for the barrier
`effect of the adhesive composition.
`In order to characterize the barrier effect, the oxygen
`transmission rate OTR and the water vapour transmission
`rate WVTR are usually specified. In this case, the respective
`rate indicates the area- and time-related flow of oxygen and
`water vapour through a film under specific conditions of
`temperature and partial pressure and, if appropriate, further
`measurement conditions such as relative air humidity. The
`lower these values, the better the suitability of the respective
`material for encapsulation. In this case, the specification of
`the permeation is not only based on the values for WVTR or
`OTR but also always includes a specification with regard to
`the average path length of the permeation, such as e.g. the
`thickness of the material, or a normalization to a specific
`path length.
`The permeability P is a measure of how permeable a body
`is to gases and/or liquids. A low P value denotes a good
`barrier effect. The permeability P is a specific value for a
`defined material and a defined permeant under steady-state
`conditions for a specific permeation path length, partial
`pressure and temperature. The permeability P is the product
`of diffusion term D and solubility term S:
`
`The solubility term S in the present case describes the
`affinity of the barrier adhesive composition for the permeant.
`In the case of water vapour, for example, a low value is
`achieved for S by hydrophobic materials. The diffusion term
`D is a measure of the mobility of the permeant in the barrier
`material and is directly dependent on properties such as the
`
`10
`
`15
`
`The present invention relates to a method for encapsulat
`ing an electronic arrangement in accordance with the pre
`amble of Claim 1 and to the use of a pressure-sensitive
`adhesive composition for encapsulating an electronic
`arrangement in accordance with the preamble of Claim 5.
`(Opto)electronic arrangements are being used more and
`more often in commercial products or are about to be
`introduced to the market. Such arrangements comprise inor
`ganic or organic electronic structures, for example organic,
`organometallic or polymeric semiconductors or else combi
`nations thereof. Depending on the desired application, these
`arrangements and products are embodied in rigid or flexible
`fashion, where there is an increasing demand for flexible
`arrangements. Such arrangements are produced for example
`by printing methods such as relief printing, intaglio printing,
`screen printing, planographic printing or else so-called “non
`impact printing such as, for instance, thermal transfer
`printing, inkjet printing or digital printing. In many cases,
`however, use is also made of vacuum methods, such as e.g.
`chemical vapour deposition (CVD), physical vapour depo
`sition (PVD), plasma-enhanced chemical or physical depo
`sition methods (PECVD), sputtering, (plasma) etching or
`vapour deposition, wherein the patterning is generally
`effected by means of masks.
`Examples that may be mentioned here of (opto)electronic
`applications that are already commercial applications or are
`interesting in terms of their market potential include elec
`trophoretic or electrochromic structures or displays, organic
`or polymeric light-emitting diodes (OLEDs or PLEDs) in
`indication and display devices or as lighting, electrolumi
`nescent lamps, organic Solar cells, preferably dye or polymer
`Solar cells, inorganic Solar cells, preferably thin-film Solar
`cells, in particular based on silicon, germanium, copper,
`indium and selenium, organic field effect transistors, organic
`Switching elements, organic optical amplifiers, organic laser
`diodes, organic or inorganic sensors or else organically or
`inorganically based RFID transponders.
`What can be regarded as a technical challenge for real
`izing sufficient lifetime and function of (opto)electronic
`arrangements in the field of inorganic and/or organic (opto)
`electronics, but especially in the field of organic (opto)
`electronics, is protecting the components contained therein
`45
`against permeants. Permeants can be a multiplicity of low
`molecular-weight organic or inorganic compounds, in par
`ticular water vapour and oxygen.
`A large number of (opto)electronic arrangements in the
`field of inorganic and/or organic (opto)electronics, espe
`cially when using organic raw materials, are sensitive both
`to water vapour and to oxygen, where the penetration of
`water vapour is rated as a fairly major problem for many
`arrangements. Protection by means of an encapsulation is
`necessary during the lifetime of the electronic arrangement,
`therefore, since otherwise the performance deteriorates over
`the application period. Thus, for example as a result of an
`oxidation of the constituents for instance in the case of
`light-emitting arrangements such as electroluminescent
`lamps (EL lamps) or organic light-emitting diodes (OLED)
`the luminosity, in the case of electrophoretic displays (EP
`displays) the contrast or in the case of Solar cells the
`efficiency can decrease drastically within a very short time.
`In the case of inorganic and/or organic (opto)electronics,
`in particular in the case of organic (opto)electronics, there is
`a particular need for flexible adhesive solutions that consti
`tute a permeation barrier to permeants such as oxygen and/or
`
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`US 9,627,646 B2
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`molecular mobility or the free volume. Relatively low
`values are often achieved for D in the case of highly
`crosslinked or highly crystalline materials. However, highly
`crystalline materials are generally less transparent and
`higher crosslinking leads to a lower flexibility. The perme
`ability Pusually rises with an increase in molecular mobility,
`for instance even if the temperature is increased or the glass
`transition point is exceeded.
`Approaches for increasing the barrier effect of an adhe
`sive composition have to take account in particular of the
`two parameters D and S with regard to the influence on the
`permeability of water vapour and oxygen. In addition to
`these chemical properties, effects of physical influences on
`the permeability also have to be considered, in particular the
`average permeation path length and interface properties
`(flowing behaviour of the adhesive composition, adhesion).
`The ideal barrier adhesive composition has low D values and
`S values in conjunction with very good adhesion on the
`substrate.
`A low solubility term S is usually insufficient for achiev
`ing good barrier properties. One classic example of this is
`siloxane elastomers, in particular. The materials are
`extremely hydrophobic (small solubility term) but have a
`comparatively small barrier effect against water vapour and
`oxygen as a result of their freely rotatable Si-O bond (large
`diffusion term). A good balance between solubility term S
`and diffusion term D is necessary, therefore, for a good
`barrier effect.
`To date, liquid adhesives and adhesives based on epoxides
`have primarily been used for this purpose (WO98/21287 A1;
`U.S. Pat. No. 4,051,195 A: U.S. Pat. No. 4,552,604 A).
`These have a small diffusion term D as a result of high
`crosslinking. Their main area of use is edge adhesive bond
`ings of rigid arrangements, but also moderately flexible
`arrangements. Curing is effected thermally or by means of
`UV radiation. A whole-area adhesive bonding is virtually
`impossible on account of the shrinkage occurring as a result
`of the curing, since stresses occur between adhesive and
`Substrate during curing, which stresses can in turn lead to
`delamination.
`40
`The use of said liquid adhesives entails a series of
`disadvantages. This is because low-molecular-weight con
`stituents (VOC volatile organic compound) can damage
`the sensitive electronic structures of the arrangement and
`hinder handling in production. The adhesive has to be
`applied to each individual constituent of the arrangement in
`a complicated manner. It is necessary to procure expensive
`dispensers and fixing devices in order to ensure accurate
`positioning. Moreover, the manner of application prevents a
`fast continuous process and the lamination step Subsequently
`required can also make it more difficult to achieve a defined
`layer thickness and adhesive bonding width within narrow
`limits as a result of the low viscosity.
`Furthermore, such highly crosslinked adhesives have only
`a low flexibility after curing. The use of thermally cross
`linking systems is limited in the low temperature range or in
`two-component systems by the pot life, that is to say the
`processing time until gelation has taken place. In the high
`temperature range and in particular in the case of long
`reaction times, the sensitive (opto)electronic structures in
`turn limit the usability of Such systems—the maximum
`temperatures that can be employed in the case of (opto)
`electronic structures are often around 60° C. since prelimi
`nary damage can already occur starting at this temperature.
`In particular flexible arrangements which contain organic
`electronics and are encapsulated with transparent polymer
`films or composites composed of polymer films and inor
`
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`4
`ganic layers impose narrow limits here. This also applies to
`lamination steps under high pressure. In order to achieve an
`improved durability, what is advantageous here is dispens
`ing with a thermally loading step and lamination under
`lower pressure.
`As an alternative to the thermally curable liquid adhe
`sives, radiation-curing adhesives are now also being used in
`many cases (US 2004/0225.025 A1). The use of radiation
`curing adhesives avoids a lengthy thermal loading of the
`electronic arrangement. However, the irradiation gives rise
`to a momentary heating of the arrangement at points, since
`in general a very high proportion of IR radiation is also
`emitted alongside a UV radiation. Further abovementioned
`disadvantages of liquid adhesives such as VOC, shrinkage,
`delamination and low flexibility are likewise retained. Prob
`lems can arise as a result of additional volatile constituents
`or disassociation products from the photoinitiators or sen
`sitizers. In addition, the arrangement has to be transmissive
`to UV light.
`Since constituents of organic electronics, in particular,
`and many of the polymers used are often sensitive to UV
`loading, relatively lengthy exterior use is not possible with
`out further additional protective measures, for instance fur
`ther covering films. The latter can only be applied after UV
`curing in the case of UV-curing adhesive systems, which
`additionally increases the manufacturing complexity and the
`thickness of the arrangement.
`US 2006/0100299 A1 discloses a UV-curable pressure
`sensitive adhesive tape for encapsulating an electronic
`arrangement. The pressure-sensitive adhesive tape com
`prises an adhesive composition based on a combination of a
`polymer having a softening point of greater than 60° C., a
`polymerizable epoxy resin having a softening point of less
`than 30° C. and a photoinitiator. The polymers can be
`polyurethane, polyisobutylene, polyacrylonitrile, polyvi
`nylidene chloride, poly(meth)acrylate or polyester, but in
`particular an acrylate. Adhesive resins, plasticizers or fillers
`are furthermore contained.
`Acrylate compositions have a very good resistance to UV
`radiation and various chemicals, but have very different
`bond strengths on different substrates. While the bond
`strength on polar Substrates Such as glass or metal is very
`high, the bond strength on non-polar Substrates such as
`polyethylene or polypropylene, for example, is rather low.
`Here there is the risk of diffusion at the interface to a
`pronounced extent. Moreover, these compositions are highly
`polar, which fosters a diffusion of water vapour, in particu
`lar, despite Subsequent crosslinking. This tendency is further
`amplified by the use of polymerizable epoxy resins.
`The embodiment as a pressure-sensitive adhesive com
`position mentioned in US 2006/0100299 has the advantage
`of a simple application, but likewise suffers from possible
`dissociation products as a result of the photoinitiators con
`tained, a necessary UV transmissivity of the construction
`and a reduction of the flexibility after curing. Moreover,
`owing to the Small proportion of epoxy resins or other
`crosslinkers, which is necessary for maintaining the tack and
`in particular the cohesion, the crosslinking density that can
`beachieved is only very much lower than that which can be
`achieved by means of liquid adhesives.
`Pressure-sensitive adhesive tapes generally require a cer
`tain time, Sufficient pressure and a good balance between
`Viscous fraction and elastic fraction owing to the relatively
`high-molecular-weight polymers in contrast to liquid adhe
`sives for a good wetting and adhesion on the Surface. The
`Subsequent crosslinking of the adhesive compositions gen
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`erally leads to a shrinkage of the composition. This can lead
`to a reduction of the adhesion at the interface and in turn
`increase the permeability.
`WO 2007/087281 A1 discloses a transparent flexible
`pressure-sensitive adhesive tape based on polyisobutylene
`(PIB) for electronic applications, in particular OLED. Poly
`isobutylene having a molecular weight of more than 500 000
`g/mol and a hydrogenated cyclic resin are used in this case.
`The use of a photopolymerizable resin and of a photoinitia
`tor is optionally possible.
`On account of their low polarity, adhesive compositions
`based on polyisobutylene have a good barrier against water
`vapour, but a relatively low cohesiveness even at high
`molecular weights, for which reason they often have a low
`shear strength at elevated temperatures. The fraction of
`low-molecular-weight constituents cannot be reduced arbi
`trarily since otherwise the adhesion is significantly reduced
`and the interface permeation increases. When using a high
`fraction of functional resins, which is necessary on account
`of the very low cohesion of the composition, the polarity of
`the composition is increased again and the solubility term is
`thus increased.
`By contrast, a pressure-sensitive adhesive composition
`with pronounced crosslinking exhibits good cohesion, but
`the flow behaviour is impaired. The pressure-sensitive adhe
`sive composition can adapt to the roughness of a Substrate
`surface only to an insufficient extent, whereby the perme
`ation at the interface is increased. Moreover, a pressure
`sensitive adhesive composition with pronounced crosslink
`ing can dissipate deformation energy, such as occurs under
`loading, only to a relatively small extent. The bond strength
`is reduced by both phenomena. By contrast, a slightly
`crosslinked pressure-sensitive adhesive composition can
`indeed readily flow on rough Surfaces and dissipate defor
`mation energy, Such that the requirements made of adhesion
`can be met, but the pressure-sensitive adhesive composition
`withstands a loading only to an inadequate extent on account
`of a reduced cohesion.
`The prior art additionally discloses a pressure-sensitive
`40
`adhesive composition without barrier properties (WO
`03/065470 A1), which is used as a transfer adhesive com
`position in an electronic construction. The adhesive com
`position contains a functional filler that reacts with oxygen
`or water vapour within the construction. A simple applica
`tion of a scavenger within the construction is thus possible.
`For sealing the construction towards the outside, a further
`adhesive having low permeability is used.
`An adhesive composition based on vinylaromatic block
`copolymers is known from the prior art, for example from
`U.S. Pat. No. 4,985,499 A1. Said document describes vari
`ous advantageous formulations of the adhesive composition.
`Furthermore, the barrier effect of block copolymers is
`known from the prior art (US 2002/0188053 A1). Polymers
`based thereon are used here for the sealing of electrophoretic
`displays in that after application they are coated with a
`sealing layer and thus fixed.
`It is an object of the present invention to specify a method
`for encapsulating an electronic arrangement against per
`meants, in particular water vapour and oxygen, which can be
`carried out in a simple manner and by means of which at the
`same time a good encapsulation is obtained. Furthermore,
`the intention is to increase the lifetime of (opto)electronic
`arrangements by the use of a suitable, in particular flexible,
`adhesive composition.
`The present invention solves the problem described above
`by means of a method in accordance with claim 1. Patent
`
`50
`
`45
`
`55
`
`60
`
`65
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`6
`Claim 5 and 19 describe coordinate solutions. The respective
`dependent claims relate to preferred configurations and
`developments.
`The present invention is firstly based on the insight that,
`despite the disadvantages described above, it is nevertheless
`possible to use a pressure-sensitive adhesive composition for
`encapsulating an electronic arrangement in the case of which
`the disadvantages described above with regard to pressure
`sensitive adhesive compositions do not occur or occur only
`to a reduced extent. This is because it had been found that
`a pressure-sensitive adhesive composition based on
`vinylaromatic block copolymers is particularly suitable for
`encapsulating electronic arrangements. According to the
`invention, a pressure-sensitive adhesive composition based
`on vinylaromatic block copolymers is correspondingly pro
`vided and applied to the regions of the electronic arrange
`ment that are to be encapsulated. Since the adhesive com
`position is a pressure-sensitive adhesive composition,
`application is particularly simple since there is no need to
`effect pre-fixing or the like. Depending on the configuration
`of the pressure-sensitive adhesive composition, Subsequent
`treatment is no longer necessary either.
`In the field of adhesives, pressure-sensitive adhesive
`compositions are distinguished in particular by their perma
`nent tack and flexibility. A material having permanent tack
`has to have a suitable combination of adhesive and cohesive
`properties at every point in time. This characteristic distin
`guishes the pressure-sensitive adhesive compositions from
`reactive adhesives, for example, which afford hardly any
`cohesion in the unreacted State. For good adhesion proper
`ties it is necessary to adjust pressure-sensitive adhesive
`compositions such that there is an optimum balance between
`adhesive and cohesive properties.
`In the present case, encapsulation denotes not only an
`all-encompassing enclosure with said pressure-sensitive
`adhesive composition but also even a regional application of
`the pressure-sensitive adhesive composition on the regions
`of the (opto)electronic arrangement that are to be encapsu
`lated, for example a covering on one side or a framing of an
`electronic structure.
`By virtue of the selection of the constituents of the
`pressure-sensitive adhesive composition and the resultant
`low polarity resulting from a non-polar block of the
`vinylaromatic block copolymer and the resultant low solu
`bility term (S) of the diffusion coefficient, a low permeation
`capability of permeants such as water vapour and oxygen,
`but in particular of water vapour, is achieved. Owing to the
`formation of at least two domains within the block copoly
`mer, in addition a very good cohesion and at the same time
`improved barrier properties are obtained. By means of
`further components, as described below, depending on the
`requirements of the (opto)electronic arrangement, it is pos
`sible, for instance by means of a crosslinking reaction, for
`the properties to be advantageously adapted to the require
`mentS.
`The advantage of this present invention, then, in com
`parison with other pressure-sensitive adhesive composi
`tions, is the combination of very good barrier properties with
`respect to oxygen and primarily with respect to water vapour
`in conjunction with good interface adhesion on different
`Substrates, good cohesive properties and, in comparison with
`liquid adhesives, a very high flexibility and simple applica
`tion in the (opto)electronic arrangement and during/in the
`encapsulation. Depending on the embodiment of the pres
`Sure-sensitive adhesive composition, adhesive compositions
`based on vinylaromatic block copolymers afford a good
`resistance to chemicals and ambient influences. Further
`
`Ex.1014
`APPLE INC. / Page 7 of 15
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`7
`more, specific embodiments also comprise transparent adhe
`sive compositions, which can be employed especially for
`use in (opto)electronic arrangements since a reduction of
`incident or emerging light is kept very small.
`The pressure-sensitive adhesive composition based on
`vinylaromatic block copolymers is therefore distinguished
`not only by good processability and coatability but also by
`good product properties with regard to adhesion and cohe
`sion and by a good barrier effect with respect to oxygen and
`a very good barrier effect with respect to water vapour, in
`particular in comparison with pressure-sensitive adhesive
`compositions based on acrylates, silicones, or vinylacetate.
`Such a pressure-sensitive adhesive composition can be inte
`grated in a simple manner into an electronic arrangement, in
`particular also into Such an arrangement requiring high
`flexibility. Further particularly advantageous properties of
`the pressure-sensitive adhesive composition are similarly
`good adhesion on different Substrates, high shear strength
`and high flexibility. Moreover, a low interface permeation is
`also obtained as a result of a very good adhesion to the
`Substrate. Advantageous arrangements that combine the
`abovementioned advantages and thereby accelerate and sim
`plify the encapsulation process are obtained by the use of the
`formulations described here for the encapsulation of (opto)
`electronic structures.
`Since, in specific embodiments of the pressure-sensitive
`adhesive composition, no further thermal process steps or
`irradiation are/is necessary, no shrinkage occurs as a result
`of a crosslinking reaction and the pressure-sensitive adhe
`sive composition is present as a web-type material or in a
`form correspondingly adapted to the electronic arrangement,
`it is the case that the composition can be integrated into the
`process for the encapsulation of the (opto)electronic con
`struction simply and rapidly under low pressure. The dis
`advantages usually associated with the processing steps
`avoided, such as thermal and mechanical loadings, can thus
`be minimized. An encapsulation by lamination of at least
`parts of the (opto)electronic structures with a planar barrier
`material (e.g. glass, in particular thin glass, metal-oxide
`coated films, metal films, multilayer Substrate materials) is
`possible with a very good barrier effect in a simple role-to
`role process. The flexibility of the entire construction
`depends, besides the flexibility of the pressure-sensitive
`adhesive composition, on further factors, such as geometry
`and thickness of the (opto)electronic structures or the planar
`barrier materials. The high flexibility of the pressure-sensi
`tive adhesive composition makes it possible, however, to
`realize very thin, pliable and flexible (opto)electronic struc
`tures. The term “pliable' used should be understood to mean
`the property that the curvature of a curved object such as a
`drum with a specific radi