Manufacturing multilayer devices

Abstract

A method for manufacturing multilayer devices is presented where the device comprises a first layer (104, 304) and at least one second layer (106, 306) to be deposited on top of the first layer. The method comprises mixing (200) a first solvent with a second solvent to obtain a solvent mixture, the first solvent dissolving the material of the first layer (104, 304) and the second solvent dissolving the material of the second layer (106, 306); the amount of the second solvent being larger than the amount of the first solvent; mixing (202) the solvent mixture with the material of the second layer (106, 306) to form an ink or slurry and depositing (204) the obtained ink or slurry on top of the first layer (104, 304) as the second layer (106, 306).

Description

[0001] MANUFACTURING MULTILAYER DEVICES

[0002] Technical Field

[0003] The exemplary and non-limiting embodiments of the invention relate generally to manufacturing multilayer devices.

[0004] Background

[0005] Manufacturing electronic components has been known since 1960s, but only recently the technology has advanced in such a manner that the technology is rapidly growing and widely taken into use.

[0006] Printed batteries or energy storage devices are new kinds of batteries created through advanced printing methods. These devices are made up of multiple layers of materials, such as electrolytes and electrodes, which are typically applied onto a substrate that can be flexible using various printing techniques.

[0007] Some of these devices can be classified as thin-film batteries. The substrate can be made of various materials, including aluminium, copper, or other metals. The key components of the battery's layers are the anode, cathode, and electrolyte.

[0008] In case of multilayer devices, the smooth interaction of different layers is important for the device operation.

[0009] Brief description

[0010] According to an aspect of the present invention, there is provided a method of claim 1.

[0011] According to an aspect of the present invention, there is provided a device of claim 11.

[0012] The scope of protection sought for various embodiments of the invention is set out by the independent claims.

[0013] The embodiments and or examples and features, if any, described in this specification that do not fall under the scope of the independent claims are to be interpreted as examples useful for understanding various embodiments of the invention.

[0014] Brief description of the drawings In the following the invention will be described in greater detail by means of preferred embodiments with reference to the accompanying drawings, in which

[0015] Figure 1 illustrates an example of a multilayer device;

[0016] Figure 2 is a flowchart illustrating an embodiment;

[0017] Figure 3 illustrates another example of a multilayer device;

[0018] Detailed description of some embodiments

[0019] Printing technology enables creating electronic devices as stacks of various layers in a straightforward and cost-efficient manner. Additionally, the capability to introduce new or enhanced features, such as mechanical flexibility, is a significant factor. There are various printing methods, and the choice of printing technique is influenced by the specific demands of the printed layers, the characteristics of the materials used, and both economic and technical factors related to the final products.

[0020] In electric or electronic devices such as batteries or energy storage systems it is important that the flow of electrons and ions in the respective layers is as fluent as possible. As these devices are constructed of multiple layers the vital issue is the interaction of different layers. There may be undesired interactions between various layers which cause disturbances in the ion and electron transfer across the layers of the device.

[0021] Fig. 1 illustrates a simplified example of a multilayer device. The device 100 may be a battery or energy storage device or any other electronic multilayer device. The layers of the device are typically deposited on a substrate 102. In this example, the device 100 comprises as a first layer 104 of a given material. The device further comprises a second layer 106 of another material. The border 108 between the layers is hard and may cause an additional boundary and limit transfer of electrons and ions between the layers.

[0022] The flowchart of Fig. 2 illustrates an embodiment. The flowchart illustrates an example of an embodiment of a method of manufacturing multilayer devices, where the device comprises a first layer 104 and at least one second layer 106 to be deposited on top of the first layer.

[0023] In step 200, a first solvent is mixed with a second solvent to obtain a solvent mixture. The first solvent dissolves the material of the first layer and the second solvent dissolves the material of the second layer. The amount of the second solvent is larger than the amount of the first solvent.

[0024] In an embodiment, the amount of the second solvent is at least three times the amount of the first solvent.

[0025] In an embodiment, the ratio of the first and second solvent is 1-33% to 99-67%.

[0026] In step 202, the solvent mixture is mixed with the material of the second layer to form an ink or slurry.

[0027] In step 204, the obtained ink or slurry is deposited on top of the first layer as the second layer.

[0028] In an embodiment, the first layer is on top of another layer. Thus, the described solution is not limited to two-layer structures with only the first and second layers.

[0029] In general, it is known to use solvents in the printing process. The main purpose of solvents is to dissolve the host material for subsequent deposition. After the deposition process, the solvent's role is complete, and it may be removed from the host material, typically through evaporation. Depending on the host materials, solvents can either dissolve them or keep them suspended.

[0030] When multilayer devices or structures are created using a printing process, where one layer is covered by another, it is important to control interfacial interactions, as these can affect the behavior of the entire stack of layers.

[0031] In an embodiment, the use of a mix of solvents with different dissolving properties and polarities is introduced. As illustrated in the example multilayer device of Fig.l, the device comprises a first layer 104 of a given material, which may be denoted here as material 1. The second layer 106 which is to be deposited on top of the first layer, is of another given material, which may be denoted here as material 2.

[0032] Typically, depending on the selection of solvents, material 2, after deposition, would either start dissolving and penetrating the structure of material 1 or remain on the surface without affecting material 1. In an embodiment, it is proposed to utilise a mix of solvents to dissolve material 2. This mix will consist of a main solvent, denoted here as a second solvent that dissolves material 2 of the second layer but does not dissolve material 1 of the first layer.

[0033] A secondary solvent, denoted here as the first solvent, in a smaller ratio within the mix of solvents, will have the ability to dissolve material 1 of the first layer. This composition will allow partial dissolution of the surface of material 1 with a very limited penetration into its structure. By partially dissolving the surface, a strong and well-connected interface between the layers will be created.

[0034] In an embodiment, the amount of the second solvent is at least three times the amount of the first solvent. In an embodiment, the ratio of the first and second solvent is 5-15% / 95-85 %.

[0035] In an embodiment, the boiling point of the first solvent is lower than the boiling point of the second solvent. This ensures that it evaporates first, before the second solvent, leaving the structure of material 1 intact.

[0036] The purpose of the second solvent is to dissolve the deposited material and create a homogeneous ink / slurry. The purpose of the first solvent is to predissolve the surface of the first layer beneath the deposited second layer. The second solvent has a higher boiling point than the first solvent. This leads to slower evaporation and enabling the deposited material to settle uniformly. In contrast, the first solvent has a lower boiling point and thus it evaporates faster, only partially dissolving the first layer beneath without adversely affecting it.

[0037] In an embodiment, in addition to differences in boiling points, the selection of the first and the second solvent is based on the solvability of the materials of the first and second layer. In an embodiment, the selection of the first and the second solvent takes into account the chemical properties of the materials of the first and second layer.

[0038] In an embodiment, the selection of the solvents constituting the mix may be based on Hansen solubility parameters and other chemical properties. The widely recognized system predicts material solubility and determines the suitability of solvents to dissolve the deposited material and pre-dissolve the material beneath. The system is based on a three-parameter model: dispersion forces (6d) between molecules, polar forces (6p) between molecules, and hydrogen bonding forces (6h) between molecules.

[0039] In an embodiment, binder material of the first layer is taken into account when selecting the first solvent.

[0040] In an embodiment, the first and / or second solvent are mixed from one or more ingredients.

[0041] Fig. 3 illustrates a simplified example of a multilayer device manufactured according to the above explained method. . The device 300 may be a battery or energy storage device or any other electronic multilayer device. As with the device of Fig.l, the layers of the device are deposited on a substrate 302. In this example, the device 300 comprises as a first layer 304 of a given material. The device further comprises a second layer 306 of another material. As the second layer 306 is deposited on top of the first layer with the above explained method, the border 308 between the layers is not hard but forms a smooth interface between the layers without any voids or gaps.

[0042] The materials 1 and 2 of the layers may be selected from a multitude of materials known in the art. As a non-limiting example, the first solvent may be for example dimethylformamide (DMF) having a boiling point of 153°C. The second solvent may be for example Cyrene having a boiling point of 226°C. The ratio of the solvents may be 15 / 85, for example. The first layer 304 may be an electrode that uses polyvinylidene fluoride (PVDF) as a binder material.

[0043] Cyrene dissolves the material of the second layer 306 to be deposited but does not affect the first layer 304.

[0044] DMF can dissolve the deposited material and the PVDF layer 304 beneath.

[0045] As there is a limited amount of DMF and it evaporates faster, the first layer 304 is only partially affected by the deposition process.

[0046] The pre-dissolved first layer allows the creation of a smooth interface 308 between the first and second layer with enhanced adhesion and charge transfer between the layers.

[0047] In an embodiment, in the border area between the first and second layers the content of the material of one layer uninterruptedly reduces and is replaced by the content of the other layer. This provides the smooth interface 308 between the first and second layer.

[0048] In an embodiment, the thickness of the border area 308, where the materials of the layers are intermingled, is at most a third of the thickness of either layer.

[0049] Thus, the created multilayer device comprises multiple layers where at least two layers next to each other are composed of different materials and at the border of the layers the content of the material of one layer uninterruptedly reduces and is replaced by the content of the other layer, where the thickness of the border area is at most third of the thickness of either layer.

[0050] It will be obvious to a person skilled in the art that, as the technology advances, the inventive concept can be implemented in various ways. The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims.

Claims

Claims1. A method of manufacturing multilayer devices, the device comprising a first layer (104, 304) and at least one second layer (106, 306) to be deposited on top of the first layer, characterized in that mixing (200) a first solvent with a second solvent to obtain a solvent mixture, the first solvent having a lower boiling point than the second solvent and partial dissolution of the surface of the first layer (104, 304) with limited penetration into its structure and the second solvent dissolving the material of the second layer; the amount of the second solvent being larger than the amount of the first solvent; mixing (202) the solvent mixture with the material of the second layer (106, 306) to form an ink or slurry; depositing (204) the obtained ink or slurry on top of the first layer (104, 304) as the second layer (106, 306), the selection of the solvents constituting a mix based on Hansen solubility parameters for predicting material solubility and dissolvability of the deposited material and pre-dissolve the material beneath.

2. The method of claim 1, characterized in that the amount of the second solvent is at least three times the amount of the first solvent.

3. The method of any preceding claim, characterized in that the boiling point of the first solvent is lower than the boiling point of the second solvent.

4. The method of any preceding claim, characterized in that selecting the first and the second solvent based on the solvability of the materials of the first and second layer (106, 306).

5. The method of any preceding claim, characterized in that selecting the first and the second solvent based on the chemical properties of the materials of the first and second layer (104, 304; 106, 306).

6. The method of any preceding claim, characterized in that selecting the first and the second solvent based on Hansen solubility parameters of the solvents.

7. The method of any preceding claim, characterized in that taking binder material of the first layer (104, 304) into account when selecting the first solvent.

8. The method of any preceding claim, characterized in that mixing the first and / or second solvent from one or more ingredients.

9. The method of any preceding claim, characterized in that the first layer (104, 304) is on top of a substrate.

10. The method of any preceding claim, characterized in that the first layer (104, 304) is on top of another layer.

11. A multilayer device comprising multiple layers, characterized in that at least two layers (104, 304; 106, 306) next to each other are composed of different materials and at the border of the layers the content of the material of one layer uninterruptedly reduces and is replaced by the content of the other layer, where the thickness of the border area is at most third of the thickness of either layer.

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