PAPER-IN-RESIN ELECTRONICS - PROCESS FOR PRODUCING IT AND APPLICATION IN MANUFACTURED PRODUCTS

Abstract

The invention relates to a paper-based printed electronic device comprising one or more sheets of paper that is impregnated with a resin in way to fill the voids (or pores) of porous networks of cellulose fibers and in particular to saturate said porous networks of cellulose fibers, as well as to coat the outer surfaces of the printed electronics with said resin. A fully encapsulated electronic device is obtained which is protected against external environmental and physical damages such as against moisture and oxygen and has acquired sufficient resistance to tearing. The impregnated and encapsulated electronic device can then be successfully integrated into an object in a form of a flat or curved monolithic structure. This may especially be achieved through a lamination process, as said device sustains high pressure, high temperature, does not create bubbles, does not delaminate, and can be fully embedded into an end product.

Claims

1.-22. (canceled)

23. An electronic device comprising a plurality of sheets assembled in a direction perpendicular to the plane of the sheets, wherein at least one of said sheets is a sheet of paper comprising a printed trace, pattern, and/or layer of an electronic ink, and wherein the assembly of plurality of sheets is impregnated and encapsulated with a resin in a form of a flat or curved monolithic structure.

24. The electronic device according to claim 23, wherein at least two of the plurality of sheets are paper sheets comprising printed traces, patterns, and/or layers of a conductive ink.

25. The electronic device according to claim 23, wherein all paper sheets have a Bendtsen porosity greater than 1 ml/min.

26. The electronic device according to claim 23, wherein the at least one paper sheet comprises a printed trace, pattern, and/or layer of an electronic ink having a Bekk smoothness greater than 50 s.

27. The electronic device according to claim 23, wherein the at least one paper sheet comprises: a printed trace or layer of a semiconductive ink and/or, a printed trace or layer of a dielectric ink.

28. The electronic device according to claim 27, wherein the at least one paper sheet comprises one or more traces, patterns, and/or layers of a conductive ink, and/or one or more traces, patterns, and/or layers of a semiconductive ink, and/or one or more traces, patterns, and/or layers of a dielectric ink.

29. The electronic device according to claim 23, wherein the at least one paper sheet comprises one or more types of conductive inks, and/or one or more types of semiconductive inks, and/or one or more types of dielectric inks.

30. The electronic device according to claim 23, wherein each sheet in the plurality of sheets is a sheet of paper.

31. The electronic device according to claim 23, wherein each of the at least one paper sheet is a coated paper including a coating comprising a binder and pigments.

32. The electronic device according to claim 31, wherein each coated paper has at least one of the following features: a. It contains a coating composition comprising a binder with a glass transition temperature lower than 20 C.; b. It comprises 0.05 to 15 parts dry weight of viscosifying agent; c. It has a Bekk smoothness greater than 50 s.

33. The electronic device according to claim 32, wherein the coating of each coated paper comprises a binder selected from a group consisting of acrylic polymer, polyurethane, polymethyl methacrylate, styrene butadiene, vinyl acetate, polyamide, nitrocellulose or any other cellulose, polyvinyl alcohol, starch and a mixture thereof.

34. The electronic device according to claim 23, wherein: a. the conductive ink comprises metallic microparticles or nanoparticles and/or conducting polymers and/or b. the semiconductive ink comprises semiconducting microparticles or nanoparticles and/or semiconducting polymers and/or c. the dielectric ink comprises insulating polymers.

35. The electronic device according to claim 23, wherein the at least one sheet comprises at least one electronic component.

36. The electronic device according to claim 23, wherein the resin is selected from a group consisting of melamine formaldehyde (MF) resin, urea formaldehyde (UF) resin, urea-melamine-formaldehyde (UMF) resin, acrylic resin, phenolic resin, polyester resin, epoxy resin, and any mixtures thereof.

37. The electronic device according to claim 23, which is a near field communication (NFC) device, a radio frequency identification (RFID) device, a Bluetooth device, a Wi-Fi device or other ultra-high frequency device, a photovoltaic cell, an emissive display, an energy harvesting device, a loudspeaker, selective electromagnetic shielding or a multi-layer printed circuit board (PBC) replacement.

38. An object comprising the electronic device according to claim 23, wherein the electronic device is integrated into the object which comprises at least one electronic device integrated into its structure.

39. A method for producing an electronic device, comprising the steps of: (i) providing or producing a plurality of sheets, wherein at least one of said sheets is paper comprising at least one of a printed trace, pattern, and layer of an electronic ink; (ii) impregnating and encapsulating at least one of the sheets with resin and assembling the plurality of sheets in a direction perpendicular to a plane of the sheets; or (iii) assembling the plurality of sheets in a direction perpendicular to a plane of the sheets and impregnating and encapsulating said plurality of sheets with resin; (iv) laminating the plurality of sheets and, (v) forming a flat or curved monolithic structure from the plurality of sheets.

40. The method of claim 39, wherein at least one of the sheets includes a deposited or appended non-printed electronic component.

41. The method according to claim 39, further comprising: a. printing at least one sheet of the plurality of sheets with one or more traces, patterns, and/or layers of one or more conductive inks, and/or one or more traces, patterns, and/or layers of one or more semiconductive inks, and/or one or more traces, patterns, and/or layers of one or more dielectric inks by inkjet printing, offset printing, gravure printing, screen printing, flexography, and/or electrophotography and/or, b. curing or sintering the electronic ink.

42. The method according to claim 39, wherein the resin is selected from a group consisting of melamine formaldehyde (MF) resin, urea formaldehyde (UF) resin, urea-melamine-formaldehyde (UMF) resin, acrylic resin, phenolic resin, polyester resin, epoxy resin and any mixtures thereof.

43. The method according to claim 39, wherein step (iv) is carried out under a pressure in the range of 20 to 100 bars and a temperature in the range of 120 to 200 C. for a duration of 15 seconds to 90 minutes.

44. The method according to claim 39, wherein the electronic device comprises a plurality of sheets assembled in a direction perpendicular to the plane of the sheets, wherein at least one of said sheets is a sheet of paper comprising a printed trace, pattern, and/or layer of an electronic ink, and wherein the assembly of plurality of sheets is impregnated and encapsulated with a resin in a form of a flat or curved monolithic structure.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0109] FIG. 1: assembly of layers and sheets in an electronic device for photovoltaic application

[0110] FIG. 2: assembly of layers and sheets in an electronic device for emissive display application

[0111] FIG. 3: assembly of layers and sheets in an electronic device for energy harvesting application

[0112] FIG. 4: assembly of layers and sheets in an electronic device for loudspeaker application

[0113] FIG. 5: multilayer printed circuit board replacement

EXAMPLES

[0114] The inventors have provided illustration of devices encompassing Printed Electronics Circuitries on paper with improved properties accordingly overcoming shortcomings inherent to untreated paper which may remain physically fragile and tearable. These devices also solve the problem of devices built on paper that are not a self-sustainable structure, in particular when paper of low grammage is used. Accordingly it is generally considered that printed electronics circuitry on non-treated paper needs to be glued or embedded onto a support/product as a label or an inlay. Additionally, paper on its own contains 5% water, and is a poor barrier to water, grease or oxygen. Many applications are beyond the capabilities of Printed Electronics on paper in such conditions.

[0115] The inventors have provided improved solution by proposing an electronic device which involves impregnation and encapsulation of the paper sheets that it contains, including of the functionalized paper sheets after printing or depositing electronic components, with a resin. Accordingly the obtained structure although a monolith (as a result of assembly of sheets and final lamination) exhibits sufficient bending stiffness and resistance and also enables providing a barrier, in particular to moisture (water) and oxygen and optionally to grease.

[0116] The combination of resin use and laminates approach which is provided according to the invention to produce the electronic device is opening wide applications including due to its ability to provide combination of sheets (or layers) in the z-direction (perpendicular to the plane of the sheets), thereby enabling the piling up of layers of circuitries or active electronics components and their supply as a monolithic structure or laminate wherein the circuitry and more generally the electronic components are embedded. The electronic components are said to be embedded since the various sheets of the electronic device are strongly bound to each other and therefore may be considered to be an integral part of a monolithic or laminate structure.

[0117] At the end of the resin impregnation, encapsulation and lamination (enabling curing of the resin), the end product would be waterproof, oxygenproof and also greaseproof in a very integrated manner.

[0118] Printing of an electronic component or circuit on paper substrate can be carried out using a flat screen, rotary screen, flexographic, or inkjet printer. The electronic component or circuit printed using commercial silver-based inks (or other inks comprising metal particles) may then be sintered by high temperature IR (150-180 C.), thermal annealing, UV-curing or photonic curing. Printed dielectric or insulating (non-conductive) inks may be heat or UV-cured for circuitry insulation and cross-over bridges.

[0119] In order to integrate the electronic device into a product such as a paper (e.g. for the manufacture of functionalized end products such as functionalized wallpaper, especially obtained by lamination with the electronic device) a known roll-to-roll manufacturing process may be used.

[0120] According to the invention, the different sheets of the electronic device may be individually (or as subsets of sheets) impregnated with the resin. In such a case the type or composition of the resin may be identical or different for each sheet (or subset of sheets). In another embodiment, the assembly of sheets is impregnated with resin and encapsulated. In a further embodiment the electronic device is obtained after combining steps of resin impregnation of the individual sheets (or subsets of sheets) and impregnation and encapsulation of the assembly of sheets prior to their lamination.

[0121] In the following Examples the papers used to print or to deposit the functional electronic traces, patterns and/or layers are papers produced according to WO 2015/059157 or accordingly are papers commercialized under the trademark Powercoat XD.

Example 1: Photovoltaic Application

[0122] Using paper in a photovoltaic application would be considered very challenging for various reasons: [0123] Photovoltaic (PV) materials, in particular the organic printable ones, tend to be very sensitive to oxygen and water. Accordingly, excellent barrier is required. [0124] Most applications of PV are outdoor which may be regarded as not compatible with paper use due to its sensitivity to moisture.

[0125] It was however possible to conceive a suitable photovoltaic device (FIG. 1) using paper as a substrate to embed electrodes, PV layer and back printed electrode in a sandwich impregnated and encapsulated with resin. The arranged layers i.e., transparent conductive layer, PV layer, printed layer forming back electrode were provided on a sheet of support paper which was applied on a Kraft paper sheet. A transparent or translucent sheet obtained after resin impregnation of a Powercoat XD paper may also be added on top of the functional sheet obtained after deposit or printing of the electronic components. Alternatively, the transparent conductive layer may be deposited or printed on said transparentized Powercoat XD paper rather than overlapping with the other electronic components. A Kraft paper sheet is used as a balancing layer at the bottom of the device and it accordingly stabilizes the device. The process of producing a solar cell according to the invention is as follows:

[0126] 1/ Printing the different layers on Powercoat XD paper with a screen printing machine, in an inert gas atmosphere: [0127] First layer is an electrode printed with Orgacon silver ink SI-P1000X from Agfa, 3 m in thickness. [0128] Second layer is the PV layer printed with Lisicon PV-D series/Lisicon PV-A series blend as an active layer (200 nm) from Merk [0129] Third layer is a second electrode printed with Pedot/PSS EL-P5015 from Agfa, 400 nm in thickness

[0130] 2/ Impregnating the paper in step 1 with a solvent-base MF resin

[0131] 3/ Impregnating a Powercoat XD paper with a solvent-based MF resin to obtain a transparent paper

[0132] 4/ Pressing the different layers of paper, together with a Phenolic pre-impregnated kraft paper in a HPL process (160 C., 60 bars, 30 minutes).

[0133] The solar cell made by this method showed a Power Conversion Efficiency of 5% for 6 month at 23 C. and 50% humidity.

Example 2: Emissive Display Application

[0134] Using paper in a display application would be considered very challenging for various reasons: [0135] Display material, in particular the organic printable ones, tend to be very sensitive to water and oxygen. Accordingly, excellent barrier is required. [0136] Most applications of displays are mobile, handheld and require rugged and robust solutions which may be regarded as incompatible with paper solution due to its fragility.

[0137] Using various sheets of specialty paper it was possible to conceive a display (FIG. 2) using paper as a substrate to embed top transparent electrodes, a display stack (that may be emissive LED or OLED stack) and back printed electrode in a sandwich impregnated and encapsulated with resin. The arranged layers i.e., were provided on a sheet of support paper which was applied on a Kraft paper sheet. Alternatively, the transparent conductive layer may be deposited or printed on the transparentized Powercoat XD paper rather than overlapping with the other electronic components. The process of producing a light emitting diode stack according to the invention is as follows:

[0138] 1/ Printing the different layers on Powercoat XD paper with a screen printing machine, in an inert gas atmosphere: [0139] First layer is an electrode printed with Orgacon silver ink SI-P1000X from Agfa, 3 m in thickness. [0140] Second layer is the OLED layer printed with Livilux OLED series as an active layer (200 nm) from Merk [0141] Third layer is a second electrode printed with Pedot/PSS EL-P5015 from Agfa, 400 nm in thickness

[0142] 2/ Impregnating the previous paper with a solvent-base MF resin

[0143] 3/ Impregnating a Powercoat XD paper with a solvent-based MF resin to obtain a transparent paper

[0144] 4/ Pressing the different layers of paper, together with a Phenolic pre-impregnated kraft paper in a HPL process (160 C., 60 bars, 30 minutes).

[0145] OLED constructed by this process showed a working yield of 90% for 2 month at 23 C. and 50% humidity.

Example 3: Energy Harvesting Application

[0146] Using paper in an energy harvesting application would be considered very challenging for various reasons: [0147] Piezo materials, in particular the organic printable ones, tend to be very sensitive to water. Accordingly, excellent barrier is required. [0148] Most applications of energy harvesting is flooring or outdoor which may be regarded as not compatible with paper use due to its sensitivity to moisture, its rugged requirement, scratch resistance, etc. . . .

[0149] Using various sheets of specialty paper it was possible to conceive a display (FIG. 3) using paper as a substrate to embed top dcor paper, printed electrodes, piezo layer and back printed electrode in a sandwich impregnated and encapsulated with resin. The arranged layers i.e., were provided on a sheet of support paper which was applied on a Kraft paper sheet. On the support sheet rendered functional with the electronic components, a transparent or translucent sheet obtained after resin impregnation of a Powercoat XD paper may be added. Alternatively, the conductive electrode may be deposited or printed as a layer on the dcor paper rather than overlapping with the other electronic components. The process of producing an energy harvesting device according to the invention is as follows:

[0150] 1/ Printing the different layers on Powercoat XD paper with a screen printing machine: [0151] First layer is an electrode printed with Orgacon silver ink SI-P1000X from Agfa, 3 m in thickness. [0152] Second layer is the Piezzo layer printed with Piezotech FC25 ink P from Piezzotech ARKEMA, 4 m in thickness [0153] Third layer is printed with Orgacon silver ink SI-P1000X from Agfa, 3 m in thickness.

[0154] 2/ Poling the devices under 200 v (5 cycles).

[0155] 3/ Impregnating the previous paper with an aqueous-base MF resin

[0156] 4/ Impregnating a decor paper with an aqueous-based MF resin

[0157] 5/ Pressing the different layers of paper, together with Phenolic pre-impregnated kraft paper with an HPL process (160 C., 60 bars, 30 minutes).

[0158] When a pressure of 2 bars is applied to the system, a current of is generated from the device.

Example 4: Loudspeaker Application

[0159] The structure of the loudspeaker is exactly the same as the energy harvesting device in Example 3. In case of an energy harvesting device, vibrations as an energy source generate electricity, whereas in case of a loudspeaker, electricity generates vibrations. The process of producing a loudspeaker according to the invention is as follows:

[0160] 1/ Printing the different layers on Powercoat XD paper with a screen printing machine: [0161] First layer is an electrode printed with Orgacon silver ink SI-P1000X from Agfa, 3 m in thickness. [0162] Second layer is the Piezzo layer printed with Piezotech FC25 ink P from Piezzotech ARKEMA, 4 m in thickness [0163] Third layer is printed with Orgacon silver ink SI-P1000X from Agfa, 3 m in thickness.

[0164] 2/ poling the devices under 200 v

[0165] 3/ Impregnating the previous paper with an aqueous-base MF resin

[0166] 4/ Impregnating a decor paper with an aqueous-based MF resin

[0167] 5/ Press the different layers of papers, including also Phenolic pre-impregnated kraft paper with an HPL process (160 C., 60 bars, 30 minutes).

[0168] When an alternative tension of 24 V is applied to the loudspeaker, sound is generated by the device.

Example 5: Multi-Layer Printed Circuit Board (PCB) Replacement

[0169] Printed circuit board (PCB) is usually made of Epoxy Resin and FiberGlass. In the art, it was known to perform resin impregnation and lamination of layers of pre-impregnated fabrics or Kraft paper with copper metal foils to enable a succession of conductive circuitries. In such devices, discrete components were however soldered on top/bottom of the PCB. Air was used to cool the electronics down (thermal sink).

[0170] Printed Electronics Circuitry on Paper (FIG. 5) may be complex to handle, in particular when connecting to the external world is at stake. The solution provided by the invention enables Printed Electronics Papers assembly together in the z-direction, and the subsequent impregnation step with resin enables providing a rigid structure that can be easily connected.

[0171] In this device, resin encapsulates sensitive components or chemicals to protect them from oxygen and water or moisture. It also has a structural role to hold connector and reduce fragility in a protective monolithic structure wherein the circuitry and components are embedded.

[0172] Additionally key issue is the assembly mode that enables creating vias that are well aligned to enable circuitry continuity between the layers.

[0173] The process of producing a multi-layer printed circuit board (PCB) replacement is as follows:

[0174] 1/ Printing the first circuitry on Powercoat XD paper with a screen printing machine: [0175] First circuitry layer printed with an Orgacon silver ink SI-P1000X from Agfa, 3 m in thickness. [0176] holes drilled with a laser [0177] Via printed with an Orgacon silver ink SI-P1000X from Agfa,

[0178] 2/ Printing the second circuitry on Powercoat XD paper with a screen printing machine: [0179] First circuitry layer printed with an Orgacon silver ink SI-P1000X from Agfa, 3 m in thickness. [0180] holes drilled with a laser (3 mm in diameter) [0181] Via printed with an Orgacon silver ink SI-P1000X from Agfa,

[0182] 3/ Impregnating the previous papers with an aqueous base MF resin

[0183] 4/ Aligning the 2 layers with the via holes

[0184] 5/ Pressing the different layers of papers, together with Phenolic pre-impregnated kraft paper with an LPL process (180 C., 20 bars, 1 minute).

[0185] By contrast to systems provided in the art, the paper-in-resin electronics technology provides a device wherein each layer can present its circuitry and its electronics functions. In addition in the assembly of the invention, when electronics functions require barrier protection or thermal sinking, the impregnating resin brings this protection and performs the role of thermal vector.

Example 6: Examples of Papers_Suitable for Printing Electronic Inks and being Impregnated with a Resin

[0186]

TABLE-US-00001 TABLE 1 _PowercoatXD papers having basis weight (grammage) of 125 g and 200 g. POWERCOAT XD Paper Characteristics Apparatus Standards 125 g 200 g Basis L2200 NF EN ISO 536- RNE 129 202 Weight g/m.sup.2 Balance PC.110- RNE PC.111 Thickness m MI20 NF EN ISO 20534- PC.90 128 204 ISO 534- PC.91/PC.101 Bulk cm.sup.3/g 0.99 1.01 Smoothness Bekk [s] 136 80 Profilometer 1500 2000 Ra [nm] Porosity Bendtsen L&W NF Q 03-076-COFRAC PC.390 2 35 ml/min ISO 5636/3-COFRAC PC.391 Tear Tear tester NF EN 21974- RNE PC.60 MD 576 871 mN 60-220 CD 604 932 Tear Index MD 4 mN .Math. m.sup.2/g CD 5 5 Tensile Tensile tester NF EN ISO 1924- Force MD 134 183 MTC-100 COFRAC PC.20- N CD 70 93 COFRACPC.21 Elongation MD 3.23 2.94 mm CD 7.58 5.90 Stiffness Nmm Stiffness ISO 2493 MD 1.50 4.04 tester Frank CD 0.96 2.37 42067 Burst kPa Bursting tester NF Q 03-053- RNE PC0.40 386 489 Burst Index EC05 ISO 2758-RNE PCO.41 3 2 kPa .Math. m.sup.2/g Brightness ColorTouch CTHA 2045 NF Q 03-039- RNE PC.200 82.6 82.4 ISO 2470- RNE PC.201 Yellowing after ColorTouch CTHA 2045 Internal method 5 minutes at 2.8 2.6 curing (E) 180 C. Moisture Oven NF EN 20 287-PC.40 Wet weight 8.11 12.64 Content % Gallenkamp Kern Balance ISO 287-PC.41 Dry weight 7.72 12.12 Moisture content 4.81 4.11 Shrinkage % Unrestrained at 200 C./5 min MD 0.36 0.35 CD 0.71 0.70 Reconditioned at 23 C./50% RH MD 0.10 0.07 CD 0.19 0.14

TABLE-US-00002 TABLE 2 PowercoatXD papers having basis weight (grammage) of 84 g. POWERCOAT Paper Charateristics Apparatus Standards PWC CHAM Basis Weight g/m.sup.2 Sartorius L2200 NF EN ISO 536- RNE 84.0 Balance PC.110- RHE PC.111 Thickness m MI20 NF EK ISO 23534- PC.90 77 ISO 534- PC.91/PC.101 Bulk cm.sup.3/g 0.92 Smoothness Bekk (s) Recto 284 Verso 263 Porosity ml/min Bendtsen L&W NF Q 03-076-COFRAC PC.390 3.4 ISO 563S/3-CDFRAC PC.391 Tear mN Tear tester NF EN 21974-RNE PC.60 MB 447 63-320 CD 510 Tear Index MB 5 mN .Math. m.sup.2/g CD 6 Tensile Tensile tester NF EN ISO 1924- Force N MB 34.18 MTC-130 COFRAC PC.20- CD 45.34 COFRAC PC.21 Elongation mm MU 2.73 CD 10.48 Modulus Gpa DMA 50 C. MU 125 C. MB 200 C. MB Stiffness Nmm Stiffness tester ISO 2493 MU Frank 42867 CD Burst kPa Bursting tester NF Q 03-053- RNE PC0.40 218 Burst Index EC05 ISO 2758-RNE PCO.41 2.6 kPa .Math. m.sup.2/g Brightness Color Touch NF Q 03-039- RNE PC.200 81.5 CTHA 2045 ISO 2470- RNE PC.201 Yellowing after Color Touch Internal method 5 minutes at 180 C. 2.1 curing (E) CTHA 2045 5 minutes at 200 C. 5.2 Shrinkage % Unrestrained at 200 C./5 min MB 0.39 CD 0.65 Reconditioned at 23 C./50% RH MB 8.84 CD 3.15 Dieiectric Permittivity Internal method at 988 MHz dielectric loss (tan ) at 2.45 GHz Resistance [ohm] of a 10 cm line and 0.5 mm in width 43.4