Printing of multilayer circuits on graphics

Abstract

The present invention is and includes apparatuses, systems, and methods of printing multilayer circuits, graphically. The multilayer printing can include forming an electronic human-machine interface, a sensor readout or driver circuit, for example, can include continuously printing at least two functional ink layers on a substrate including one of a thermoform and an overmold, the at least two functional ink layers including at least one electrically conductive layer and at least one dielectric layer; printing at least one non-conductive, patterned ink layer in the sequence of continuous printing; curing each of the continuous printed layers after printing each of the continuous printed layers, wherein the curing of the continuous printed functional ink layers includes at least ultraviolet curing; and squeegeeing at least the one electrically conductive layer with a squeegee having a low durometer.

Description

[0001] Cross Reference to Related Applications

[0002] This application claims priority to U.S. Provisional Application No. 62 / 750,702, filed October 15, 2018, the entire contents of which are incorporated herein by reference as if set forth in their entirety. BACKGROUND TECHNICAL FIELD

[0004] The present invention relates generally to additive manufacturing printing, and more particularly, to an apparatus, system, and method for printing multi-layer circuits on graphics. BACKGROUND

[0006] In known technologies of human machine interfaces (HMI), sensor readout and driver circuits, it is common to manufacture the circuits using flexible printed circuit board (PCB) technology. When a need for graphics arises, such as for HMIs used in appliances, it is common to incorporate or glue active conductive circuits to the graphics as needed. In large part due to the fact that only this incorporation or gluing implementation is suitable to withstand the problems that arise in the complex manufacturing process of the HMI, such as thermoforming or overmolding, which are commonly used to create HMIs. Unfortunately, the expense and complexity of manufacturing using gluing and bonding, as well as such as creating active circuits separately on flexible or non-flexible printed circuit boards (PCBs), limits the available complexity and performance of the circuits currently used in typical HMIs.

[0007] Furthermore, the complexity of these incorporation, gluing, and / or PCB based implementations requires the use of many different types of equipment in the manufacturing process to produce the HMI. Therefore, there is a need to have the ability to manufacture HMIs, sensor readouts, and driver circuits using additional processes in multi-layers with a small and consistent set of equipment, allowing for additional complexity and improved performance of the HMI.

[0008] Therefore, there is a need for an apparatus, system, and method for printing multi-layer circuits on graphics. SUMMARY

[0009] The present invention is and includes apparatuses, systems, and methods of printing multi-layer circuits on graphics. The multi-layer printing can include forming an electronic human-machine interface, a sensor readout or driver circuit, for example, can include continuously printing at least two functional ink layers on a substrate that includes one of a thermoform and an overmold, the at least two functional ink layers including at least one electrically conductive layer and at least one dielectric layer; printing at least one non-conductive, patterned ink layer in the sequence of continuous printing; curing each of the continuously printed layers after printing each of the continuously printed layers, wherein the curing of the continuously printed functional ink layers includes at least ultraviolet curing; and squeegeeing at least the one electrically conductive layer with a squeegee having a low durometer, for example, less than about 70 durometer.

[0010] The sequence of continuously printed functional ink layers can include an electrically conductive layer, followed by two dielectric layers, followed by another electrically conductive layer, followed by a dielectric layer. Embodiments can also include printing an encapsulation layer over the last of the continuously printed layers. The patterned ink layer can also include a non-carbon.

[0011] The present invention can also include apparatuses, systems, and methods of forming a human-machine interface. The apparatuses, systems, and methods can include a thermoformed substrate; a plurality of ultraviolet cured functional ink layers including at least touch responsive circuitry, backlight drive circuitry adapted to illuminate the touch responsive circuitry, and a plurality of dielectric layers at least imparting functionality and protection to the touch responsive and backlight drive circuitry; and at least one patterned ink layer associating a graphic with the touch responsive circuitry.

[0012] Accordingly, the present invention provides apparatuses, systems, and methods of printing multi-layer circuits on graphics. BRIEF DESCRIPTION OF DRAWINGS

[0013] The present invention is illustrated by way of example, and not by way of limitation, in the accompanying drawings in which like reference numerals indicate similar elements and in which:

[0014] Figure 1 indicates a plurality of additively manufactured printed layers;

[0015] Figures 2A-2C indicates an exemplary multi-layer printing embodiment for a human-machine interface;

[0016] Figure 3A and 3B indicates a multi-layer printed circuit that is broken and unbroken, respectively;

[0017] Figure 4 indicates a stress point and an encapsulation layer in a multi-layer printed article; and

[0018] Figure 5 is a flowchart indicating a multi-layer printing method. DETAILED DESCRIPTION

[0019] The accompanying drawings and descriptions provided herein may have been simplified to illustrate aspects relevant to a clear understanding of the apparatuses, systems, and methods described herein, while other aspects that may be found in typical similar apparatuses, systems, and methods have been omitted for clarity. Those skilled in the art will recognize that other elements and / or operations may be necessary and / or essential for implementing the apparatuses, systems, and methods described herein. However, because such elements and operations are well known in the art and do not contribute to a better understanding of the invention, a discussion of such elements and operations may not be provided herein. Nevertheless, the invention is considered to inherently include all such elements, variations, and modifications to the described aspects that will be known to those skilled in the art.

[0020] The terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may also be intended to include the plural forms unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having” are inclusive and thus specify the presence of the stated feature, integer, step, operation, element, and / or component, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. Unless explicitly determined as an order of execution, the method steps, processes, and operations described herein should not be construed as requiring them to be performed in the specific order discussed or shown. It should also be understood that additional or alternative steps may be employed.

[0021] When an element or layer is referred to as being “on,” “joined to,” “connected to,” or “linked to” another element or layer, it may be directly on, directly joined to, directly connected to, or directly linked to the other element or layer, or there may be intermediate elements or layers present. Conversely, when an element is referred to as being “directly on,” “directly joined to,” “directly connected to,” or “directly linked to” another element or layer, there may be no intermediate elements or layers present. Other terms used to describe relationships between elements should be interpreted in a similar manner (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items.

[0022] Although the terms first, second, third, etc., may be used herein to describe various elements, components, regions, layers, and / or portions, these elements, components, regions, layers, and / or portions should not be limited by these terms. These terms are used only to distinguish one element, component, region, layer, or portion from another. Unless the context clearly indicates otherwise, terms such as “first,” “second,” and other numerical terms, when used herein, do not imply order or sequence. Therefore, without departing from the teachings of exemplary embodiments, the first element, component, region, layer, or portion discussed below may be referred to as the second element, component, region, layer, or portion.

[0023] This document discloses computer-implemented platforms, engines, systems, and methods of use. The embodiments of these platforms, engines, systems, and methods are intended to be exemplary and not restrictive. Therefore, the systems and methods described herein are adaptable to provide various types of interaction, data exchange, etc., and can be extended to provide enhancements and / or additions to the exemplary platforms, engines, systems, and methods. Therefore, this invention is intended to include all such extensions.

[0024] Furthermore, it is understood that the terms "module" or "engine" as used herein do not limit functionality to a specific physical module, but can include any number of tangible implementations of software and / or hardware components that have a transformative effect on at least a portion of the system. Typically, a computer program product according to one embodiment includes a tangible computer-usable medium (e.g., standard RAM, optical disc, USB drive, etc.) having computer-readable program code embodied therein, wherein the computer-readable program code is adapted to be executed by a processor (working in conjunction with an operating system) to implement one or more functions and methods as described below. In this respect, the program code can be implemented in any desired language and can be implemented as machine code, assembly code, bytecode, interpreted source code, etc. (e.g., via C, C++, C#, Java, Actionscript, Objective-C, JavaScript, CSS, XML, etc.).

[0025] To address the challenges of thermoforming and overmolding, such as for human-machine interface (HMI) consoles, or for appliances like washing machines, embodiments provide matching ink sets and improved 3D printing processes for multi-layer printing including graphic and functional ink layers. That is, the provided ink sets and improved printing methods allow for the use of in-print markings, for example, for the aforementioned HMIs. Furthermore, as used throughout this document, the terms “print,” “printing,” “prints,” “printings,” etc., can refer to any known type of printing method, although some embodiments may specifically use additional printing methods, such as screen printing. The type of printing used in the embodiments can vary based on the substrate used for printing (e.g., thermoforming versus overmolding versus a thin or thick film substrate added later on the thermoforming or overmolding), based on the final consumption environment for printing, and / or can vary layer-by-layer in a given print.

[0026] As used herein, thermoforming is a manufacturing process in which a thermoplastic sheet is heated to a flexible forming temperature. The thermoformed body is then shaped into a specific form and, as needed, molded and / or trimmed to produce a usable product. Historically, printing on thermoformed parts, either before or after thermoforming, has been very difficult due to the handling required for thermoforming assembly into products such as appliance HMIs. If additive printing is performed on a thermoformed part before heating, the additive printing will typically be damaged by the heat; and if printing is performed after thermoforming, the print is exposed to the remainder of the manufacturing process and the assembly of the thermoformed part, often resulting in damage to the additional print. In known art, this damage to additive printing in a thermoforming environment is exacerbated, where additive printing comprises multiple printed layers consisting of functional and graphic ink layers.

[0027] Overmolding is an injection molding process that provides significant product flexibility and improved product appearance. Therefore, it has historically been frequently used in manufacturing where the final product, such as a finished appliance with an HMI, uses complex final molded component designs. In a typical overmolding process, a pre-mold is formed by inserting a material into the mold, which is then transferred to a second mold. The molding on the insert becomes integral with the main part upon cooling. In short, in overmolding, a new layer of plastic is formed around the first molded component. As discussed above regarding thermoforming, in any attempt to use additive printing in an overmolded HMI, the processes required to form the overmolded HMI have historically led to failures, especially if the additive printing involves both functional ink layers and graphic ink layers.

[0028] As used herein, a Human Machine Interface (HMI) includes the electronics required to signal and control the status of devices and machines, where control signals are generated based on human interaction with the HMI. As a non-limiting example, HMIs can range from basic LED status indicators to backlit manual buttons to large HMI panels with responsive backlighting and capacitive or similar touchscreen interfaces. HMI applications require mechanical robustness and protection against water, dust, moisture, and over a wide temperature range, and in some environments, communication and / or secure network communication should be provided.

[0029] In short, thermoformed or overmolded HMIs may require the use of both graphic inks and functional inks. As a non-limiting example, an HMI may have two graphic ink layers and at least three, such as five, functional ink layers. Accordingly, the ink properties and substrate properties between the various functional and non-functional layers must comprise a matching set of inks to provide optimal operability of the HMI and further ensure its long lifespan.

[0030] Figure 1 This illustrates an exemplary 7-layer ink group implementation, combining functional and graphic ink groups in a uniform print. As shown, layers 1 and 2, 102 and 104 may include graphic inks 102a and 104a, respectively. Layer 3, 106, may provide conductive circuitry 106a, such as capacitive touch circuitry, allowing human interaction with the partially printed HMI. Layers 4 and 5, 108 and 110, may include dielectric layers, as may layer 7, 112. Layer 6, 114, may also provide a conductive layer allowing additional electronic conduction to provide specific active HMI aspects of the exemplary embodiment.

[0031] It is worth noting that, in the embodiments, layer 102 may be a patterned ink layer formed on the substrate of the remaining portion of the multilayer printing. The substrate may then be attached to, for example, an overmolded or thermoformed part by an adhesive. Alternatively, layer 102 may form a substrate printing layer directly printed on a receiving substrate (e.g., a receiving overmolded or thermoformed part).

[0032] Figure 2 shows more specifically the three-layer ink print for an HMI device. As shown in the figure, and as... Figure 1In the illustration, layer 1, 202, includes patterned ink printing. For reasons discussed throughout this document, by way of non-limiting example, the patterned ink layer(s) used herein may be non-conductive ink, i.e., non-carbon-based ink. In this illustration, the additive layer, i.e., layer 2, 204, includes a functional ink layer for a capacitive touch circuit 204a, which is also adapted to provide LED backlighting. As described herein, the functional conductive ink layer may be printed using silver conductive ink, as a non-limiting example, such as those provided by Henkel. As discussed throughout, the functional dielectric ink layer may be provided by DuPont, as a non-limiting example, such as, for example, DuPont's ME773 and / or ME775 dielectric inks.

[0033] In the illustrative embodiment, the capacitive touch circuit 204a may include LED driving capability for the LED backlight 206a of the capacitive touchscreen, such as... Figure 2C As shown. That is to say, in Figure 2C In the illustration, LEDs 206a are used to illuminate capacitive touch buttons in the HMI. Needless to say, in embodiments such as those shown in Figure 2, a microcontroller 210 can be employed to provide LED operation and reception of capacitive touch data. As an example, an exemplary microcontroller could be an Atmel SAM D10 Smart ARM-based microcontroller.

[0034] Needless to say, the conductive layer shown may comprise a conductive printing ink, such as Henkel Abestlek 2030 SC. LED driving capability can be provided by any means known to those skilled in the art, such as using a Panasonic DMC26404 driver. Furthermore, at least for the purpose of providing LED operation and data exchange, the conductive layer shown may be connected to a power source. As a non-limiting example, power can be provided by the device / machine to which the HMI interface is connected, such as an appliance. For example, a 5V power supply may be connected in-line. Figure 2B and 2C The circuit(s) shown can be converted from the 120V or 220V common power supply of the device to which the HMI is connected.

[0035] More specifically, and by way of non-limiting example only, Tables 1-5 below represent exemplary inks, screens, substrates, printers, scrapers, etc., to allow for the generation of Figure 1 And / or the HMI shown in 2, more specifically, although ink curing in the examples of Tables 1-5 can be performed by oven-based heating, in the exemplary embodiments, one or more layers can be cured by ultraviolet light on the ink instead of oven-based curing.

[0036] Table 1

[0037]

[0038] Table 2

[0039]

[0040] Table 3

[0041]

[0042] Table 4

[0043]

[0044] Table 5

[0045]

[0046] In some embodiments, the use of UV curing can offer various advantages over known techniques. For example, in oven / heat curing embodiments, UV curing limits or eliminates the presence of pinholes in the printed ink layer, which are formed at least because the ink tends to collapse, causing partial shrinkage of the ink layer. This layer collapse can result in pinholes being thinner in areas of the printed trace than in other areas. On the other hand, because light-based curing involves crosslinking rather than heating, the printed layer using light curing does not collapse in any part, thus essentially eliminating pinholes. Of course, those skilled in the art will understand that other methods can be used to address pinholes in one or more layers of the embodiments, such as the degree of oven / heat curing used in any of those other layers. For example, the thickness of the printed ink layer can be increased, or excess printing can occur on any given printed layer to allow for heat curing and layer shrinkage without significant pinholes.

[0047] As shown in Figure 3, without the remedial features provided in the embodiments, multilayer printing, as described in the embodiments, may produce additional problems. As a non-limiting example, Figure 3A This represents a break 302 between a first conductive layer trace 304 and a second conductive layer trace 306 located in the same layer as the first trace 304, wherein the second trace 306 of the same conductive layer is printed on a dielectric layer portion 308, but the first trace 304 is not. In previously known embodiments, the varying step height 310 caused by the addition of a dielectric layer portion 308 below the second conductive trace 306 typically results in an interruption of conductivity 302, for example, when a doctor blade is applied to a printed conductive layer comprising the first and second traces 304, 306. As those skilled in the art will understand, doctor blades are frequently used in additive printing processes to flatten the printed layer, thereby allowing subsequent printing and / or removing excess printing material.

[0048] In an exemplary embodiment, therefore, as Figure 3B As shown, a lower hardness scraper 320 is used to provide additional "tolerance" when brushing the scraper onto the printed layer at varying step heights. As a non-limiting example, the disclosed embodiments may employ a scraper 320 with a hardness in the range of 75 or less, for example, a scraper with a hardness of approximately 60. This additional tolerance, superior to known techniques, allows for the removal of less print thickness at step height 310, thereby eliminating the frequent and significant defects in known techniques. Figure 3A The conductivity of 302 shown is interrupted.

[0049] Furthermore, as will be understood, encapsulation is frequently used in known multilayer printed embodiments to protect components. However, in a manner similar to the step height discussed above, the encapsulation layer 402 may create one or more stress points 404 in the printed layer. Figure 4 This indicates that stress points 404 are generated through the encapsulation layer 402, so that a dielectric layer 406 with ink that "matches" the conductive layer 408 can be printed on the conductive layer, such that the subsequent encapsulation layer 402 does not contact the conductor, thereby preventing stress from being applied to the conductor at any of the various stress points.

[0050] It is worth noting that the overprinted dielectric layer 406 may only cover the portion of the conductive layer 408 most likely to experience stress, may only cover the conductive trace portion of the conductive layer, or may cover the entire conductive layer. Thus, as a non-limiting example, for instance... Figure 1 Layer 7 in the middle can be used globally or locally to protect the conductive layer from damage caused by [unclear text - likely a continuation of a previous sentence]. Figure 4 The effect of stress points caused by the encapsulation layer 402 shown.

[0051] As described above, and as those skilled in the art will understand, multilayer circuits with matching ink sets, such as those disclosed herein, may require curing each consecutively printed ink layer. Therefore, it is essential that the curing of one ink layer does not cause additional damage to the performance of previously printed and cured ink layers. Thus, as referenced throughout, embodiments may use ultraviolet curing methods, i.e., light-based curing methods, for at least those layers immediately adjacent to the conductive layer, if not all layers of the disclosed print.

[0052] For example, refer to again Figure 1 Table 6 below shows the process from printing the conductive layer to printing the first and second dielectric layers (e.g. Figure 1 Layers 4 and 5) maintain essentially similar resistance in the conductive layer. Conductive layer (e.g., Figure 1The consistency of the resistance of layer 3 indicates that the conductive layer retains its properties despite undergoing multiple curing processes after the conductive layer has cured (i.e., the first and second dielectric layers have cured). This retention of the conductive layer's properties through multiple curing processes is partly due to the use of ultraviolet curing in the embodiments.

[0053] Table 6

[0054] Test Resistance (Ω) 1 : Silver only 5.36±.653 2: After first dielectric 5.05±.591 3: After second dielectric 4.93±.545

[0055] Of course, other considerations can be incorporated into the development of the matching ink sets described herein. For example, it is preferable that the non-functional, i.e., patterned ink layers are non-conductive and / or require minimal curing. Therefore, as discussed herein, non-carbon inks may be preferred for patterned layers, and / or UV curing may be applied to these layers.

[0056] Furthermore, regarding the matching ink set, the RMS (root mean square of surface height) value of the patterned ink layer printing, i.e., the roughness, should be less than the thickness of the conductive layer printed on the patterned layer. In other words, if the roughness of the patterned layer is too large, the peaks and valleys generated during the printing of the conductive layer may cause the conductivity of the conductive layer to be interrupted in a manner similar to the step height problem described above. In an exemplary embodiment, the thickness of the conductive layer can be at least 2-3 times the roughness in the patterned layer. Of course, those skilled in the art will understand that other methods can be employed to "smooth" the roughness of the patterned layer printing. For example, an intermediate dielectric layer with a specific thickness, solubility, or diffusion can be provided, which will "absorb" the roughness of the patterned layer, such that when the conductive layer is printed on the intermediate dielectric layer, the conductive layer experiences a relatively smooth printing substrate in the form of the intermediate dielectric layer.

[0057] Figure 5 This is a flowchart illustrating a method 500 for forming an HMI according to an embodiment. It is worth noting that, as will be understood, regarding... Figure 5 The number and type of layers discussed are provided only as examples. That is, without departing from... Figure 5 As described above, the number and type of layers can vary for different purposes.

[0058] In step 501, a substrate is provided, such as a thermoformed part for use in an HMI. In step 502, a graphic layer formed of non-conductive, non-carbon ink is printed on the substrate. In step 504, the layer is cured using any known method. In step 506, a dielectric layer is printed, and in step 508, the layer is cured using any known method. In step 510, a conductive layer is printed. In step 512, the layer is subjected to low-hardness scraping, and in step 514, it is UV cured.

[0059] In steps 516 and 520, two dielectric layers are printed, and UV curing is performed in both steps 518 and 522. In step 530, a conductive layer is printed, which is then smoothed using a low-hardness scraper in step 532 and UV cured in step 534. Finally, a dielectric layer is printed in step 540 and UV cured in step 542.

[0060] As will be apparent from the foregoing detailed description, various features are combined in a single embodiment to simplify the invention in order to achieve the following objectives. The disclosed methods should not be construed as reflecting an intent to require more features than explicitly described herein. That is, the enumerated embodiments are provided merely as examples, and the invention includes any embodiments having more or fewer elements than the exemplary embodiments, as will be apparent to those skilled in the art from the discussion herein.

Claims

1. A method for continuous printing to form an electronic human-machine interface, comprising: At least two functional ink layers, including at least one conductive layer and at least one dielectric layer, are continuously printed on a substrate. Prior to any one of the continuously printed functional ink layers, a continuously printed patterned ink layer, including a non-carbon ink layer, is printed. The thickness of the conductive layer is 2-3 times the roughness of the patterned ink layer. The substrate is adapted to be physically bonded to one of a thermoformed part and an overmolded part. At least one non-conductive patterned ink layer is printed in a continuous printing sequence; Each continuously printed layer is cured after printing each continuously printed layer, wherein the curing of the continuously printed functional ink layers includes ultraviolet curing; as well as An encapsulation layer is printed on top of the last layer in a series of printed layers, and the last layer in the series of printed layers includes a portion of a dielectric layer that covers only the conductive traces of the conductive layer. Apply at least one conductive layer using a scraper with a hardness of less than 70.

2. The method according to claim 1, wherein, The sequence of the functional ink layers in continuous printing includes a conductive layer, followed by two dielectric layers, then another conductive layer, and then another dielectric layer.

3. The method according to claim 1, wherein, The continuously printed graphic ink layer comprises two continuously printed graphic ink layers.

4. The method according to claim 1, wherein, The combination of the continuously printed functional ink layer and the graphic ink layer comprises seven layers.

5. The method according to claim 1, wherein, The scraper has a hardness of 60.

6. A human-machine interface formed by the continuous printing method according to any one of claims 1-5, comprising: Thermoformed substrate; At least two functional ink layers, including at least one conductive layer and at least one dielectric layer, are continuously printed on the substrate, and the continuously printed patterned ink layer is printed before any of the continuously printed functional ink layers. The UV-cured functional ink layer includes at least one conductive layer, comprising at least a touch response circuit, a backlight driving circuit adapted to illuminate the touch response circuit, and a dielectric layer that imparts functionality and protection to at least the touch response and backlight driving circuit. At least one graphic ink layer that associates graphics with touch response circuitry; The thickness of the conductive layer is 2-3 times the roughness of the patterned ink layer; At least one of the UV-curable functional ink layers also includes a scraping layer, wherein the scraper has a hardness of less than 70. as well as A protective encapsulation layer is printed on the last consecutive layer of the plurality of UV-curable functional ink layers, and the last layer of the consecutive printed layers includes a portion of the dielectric layer that only covers the conductive traces of the conductive layer.

7. The human-machine interface according to claim 6, wherein, At least one patterned ink layer includes at least one UV-curable patterned ink layer.

8. The human-machine interface according to claim 6, wherein, The at least one patterned ink layer includes two patterned ink layers.

9. The human-machine interface according to claim 6, wherein, The light source used for the touch response circuit includes at least one light-emitting diode.

10. The human-machine interface according to claim 6, wherein, The touch response circuit includes a capacitive touch response circuit.

Images