WO2021206732A1

WO2021206732A1 - Blocking fluid progression among layers of fluidic devices

Info

Publication number: WO2021206732A1
Application number: PCT/US2020/027667
Authority: WO
Inventors: Donald W. Schulte; Yao Qian; Terry Mcmahon
Original assignee: Hewlett-Packard Development Company, L.P.
Priority date: 2020-04-10
Filing date: 2020-04-10
Publication date: 2021-10-14

Abstract

Examples are described herein for blocking fluid progression among layers of fluidic devices. In various examples, a fluidic device may include a cover layer with an inner boundary that defines a window through the cover layer, a circuit layer adjacent the cover layer, and a fluidic die disposed on the circuit layer within the window. The circuit layer may include a void that is adjacent the inner boundary of the window of the cover layer. An encapsulant may overlay an electrical coupling between the fluidic die and a conductive path of the circuit layer. The encapsulant may permeate into the void to form a plug that blocks progression of fluid along the inner boundary towards the electrical coupling.

Description

BLOCKING FLUID PROGRESSION AMONG LAYERS OF FLUIDIC DEVICES

Background

[0001] Fluidic devices are devices through which fluids and/or electric signals may propagate. Fluidic devices may be used by printing devices, such as fo eject fluids on a print medium. Fluidic devices may also be used for bio-medical devices, such as to perform tests on fluids.

[0002] Fluidic devices may include multiple layers. For example, some layers referred to herein as“circuit layers” may include conductive paths. Other layers may be provided as protective cover layers, e.g., on top of circuit Sayers. Other Sayers still may be adhesive Sayers. And yet other layers may take the form of molded encapsulants that are deposited at particular locations to protect particular components. These various Sayers may contact each other at various interfaces.

Brief Description of the Drawings

[0003] Features of the present disclosure are illustrated by way of example and not limited in the following figure(s), in which like numerals indicate like elements.

[0004] Figs. 1A and 1B schematically depict an example of a fluidic device that includes selected aspects of the present disclosure.

[0005] Figs. 2A, 2B, and 2C schematically depict one stage of assembly of a fluidic device configured with selected aspects of the present disclosure. [0006] Figs. 3A, 3B, and 3C schematically depict another stage of assembly of a fluidic device configured with selected aspects of the present disclosure. [0007] Figs. 4A, 4B, and 4C schematically depict another stage of assembly of a fluidic device configured with selected aspects of the present disclosure. [0008] Figs. 5Ά, 5B, and 5G schematically depict another stage of assembly of a fluidic device configured with selected aspects of the present disclosure. [0009] Figs. 6A, 6B, and 6C schematically depict another stage of assembly of a fluidic device configured with selected aspects of the present disclosure. [0010] Figs. 7A, 7B, and 7G schematically depict three stages of an alternative assembly process, in accordance with select aspects of the present disclosure.

[0011] Fig. 8 depicts an example method for practicing selected aspects of the present disclosure.

[0012] Fig. 9 depicts a simplified block diagram of an inkjet printing system in which fluidic devices configured with selected aspects of the present disclosure can be deployed, according to an example of the present disclosure.

Detailed Description

[0013] For simplicity and Illustrative purposes, the present disclosure is described by referring mainly to an example thereof. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. It will be readily apparent however, that the present disclosure may be practiced without limitation to these specific details. In other instances, some methods and structures have not been described in detail so as not to unnecessarily obscure the present disclosure, [0014] Additionally, it should be understood that the elements depicted in the accompanying figures may include additional components and that some of the components described in those figures may be removed and/or modified without departing from scopes of the elements disclosed herein, it should also be understood that the elements depicted in the figures are not drawn to scale and thus, the elements may have different sizes and/or configurations other than as shown in the figures.

[0015] When multi-layered circuits (which or may not be flexible in some cases) used for creating electrical interconnection with fluidic devices such as thermal inkjet ( " TIJ") printheads are assembled, small pockets, cracks, or gaps may form at or along the edges of various patterned interfaces between layers. As one example, a circuit layer may be partially or wholly overlaid by a cover layer constructed with, for instance, ethylene vinyl acetate (“EVA”), The cover layer In turn may be cut, e.g,, using coherent light (e.g., a laser) or other means, to create a window through the cover layer. In some cases, a fluidic die may be mounted within this window.

[0016] An inner boundary or perimeter of this window may be subsequently covered, e.g., with an encapsulant that protects an electrical coupling between the fluidic die and a conductive path of the circuit layer. However, pockets, cracks, and/or other irregularities or imperfections may form at the inner boundary of the window. Consequently, fluid, such as ink, may have a tendency to seep aiong the window’s inner boundary towards the electrical coupling, e.g., the fluid contacting electrical couplings causing a short, damaging or rendering inoperable the fluidic device.

[0017] Examples are described herein for blocking fluid progression among layers of fluidic devices, particularly among interfaces between layers. Examples described herein may be applicable, for instance, with TIJ or piezo-electric inkjet (“Plj”) printheads, printing components used for two-dimensional and/or three- dimensional printing, and/or bio-medical devices. [0018] in various examples, layer(s) in a circuit may inciude planned void(s) or cavities at various locations. These planned void(s) or cavities may be created in the layers during manufacturing and/or created post-manufacturing, e.g., using coherent light, etching, physical cutting, etc. The planned voids/cavities may take various shapes, such as elongate holes of various sizes, in various examples, a planned void or cavity may be sized, shaped, and/or positioned to receive a molded material — e.g., the encapsuiant mentioned previously — that permeates into the void/cavity and sets. Once set, this encapsuiant effectively forms what may be referred to as a “plug/’ This plug may subsequently block progression of fluid along the inner boundary of the cover layer window.

[0019] The locations at which the planned void(s) or cavities are created may be selected as being spatially aligned and/or adjacent with interfaces between, e.g., patterned edges of, various layers. For example, a planned void/cavity may be placed at a location crossing a patterned layer edge where fluid progression has been observed. The resultant plug of materia! filling this cavity may block this fluid progression along the interface at the patterned edge, e.g., to protect circuit components that may be sensitive to fluid such as ink. In some examples, the selected location may be the location of an interface between a cover layer window's inner boundary, and underlying circuit layer, and an encapsuiant that is deposited over that location, e.g., to protect an electrical connection between a fluidic die and conductive path(s) of the circuit layer.

[0020] Figs. 1 A and 1 B schematically depict a fluidic device 100 at two different stages of assembly, respectively. Fluidic device 100 may serve various purposes. In some examples, fluidic device 100 may be used to eject a fluid {e.g. , ink) onto a medium such as paper. For example, fluidic device 100 may be a print module of a printing device comprising ejection chambers for ejecting printing fluids onto a substrate or build material. In this case, fluidic device 100 may comprise a replaceable printhead module, for example. For instance, a print bar of the printing device may include a number of fluidic devices 100, which may operate in concert in order to form objects, text, and/or images on a target material. [0021] In another implementation, fluidic device 100 may be a component to be used for diagnostic tests on biological fluids. For instance, fluidic device 100 may take the form of a diagnostic test device into which fluids, such as blood, may be introduced for testing. In this case, fluidic device 100 may be a component that is replaceable after each test, such to enable successive tests with reduced amounts of waste and/or cost.

[0022] Fluidic device 100 includes a first layer 102 and a second layer 106. In some examples, first layer 102 takes the form of a circuit layer that includes conductive path(s) 104. These conductive path(s) 104 may be disposed on/in first layer 102 using various techniques, such as etching, deposition, adhesives, etc. First layer 102 may take various forms, such as a flexible or inflexible (e.g., rigid) printed circuit board. In some examples, first layer 102 may be one of multiple sections created as part of a reel or sheet.

[0023] in some examples, second layer 106 overlays all or a portion of first layer 102 and acts as a protective "cover” layer. In some examples, second layer 106 may be constructed with EVA or other similar materials, including but not limited to: polyethylenes; polypropyienes; ethylene-propylene rubbers; ethylene-propylene-diene rubbers; polyimides such as 4,4'-oxydiphenylene- pyromeilitimide; poly(1 -butene); polystyrene; poly(2-butene); poly(1-pentene); poly(2-pentene); poly(3-methy!-1-pentene); poly(4-methyl-1-pentene); 1 ,2-poly- 1,3-butadiene; 1 , 4-poly- 1 ,3-butadiene; polyisoprene; polychioroprene; poly(vinyl acetate); poly(vinylidene chloride); and mixtures and derivatives thereof, in Fig. 1A, second layer 106 has been cut, e.g., using coherent light, a blade, etching, etc,, to include a cover layer window 107 that is defined by an inner boundary 108.

[0024] A fluidic die 110 has been disposed within window 107 and an electrical coupling has been formed between fluidic die 110 and conductive path(s) 104. Fluidic die 110 refers to a die In the context of integrated circuits, and may be constructed with various materials, such as silicon. Fluidic die 110 may be used, for instance, as a base upon which structural features, such as integrated circuit elements (e.g., resistors, capacitors, transistors, etc.) may be formed through processes such as photolithographic processes and other like build-up or machining processes,

[0025] Although not shown in Fig. 1, in some examples, bonded wires may be added or manipulated to electrically couple conductive path(s) 104 of first layer 102 with fluidic die 110, As shown in Fig, 1B, this electrical coupling may be protected using, for instance, a molded material/encapsuiant 116 that is applied over part of both the first layer 102 and second layer 106, including covering part of the inner boundary 108 of cover layer window 107.

[0026] Any appropriate type of encapsulant 116 may be used in accordance with the principles described herein . For example, encapsulant 116 may be made of a ceramic, plastic, epoxy, thermoset polymer, silicone, polyurethane, another type of material, or combinations thereof. Encapsulant 116 can be used to prevent physical damage, corrosion, moisture contamination, or other undesirable conditions from reaching the electrical coupling between fluidic die 110 and conductive path(s) 104 of first layer 102, other portions of first layer 102, portions of fluidic die 110, other electronic components, or combinations thereof, [0027] The material used for encapsulant 116 may be applied to the desired areas in various ways, e g., by pouring a liquid resin over a desired area until the area is covered with the liquid resin such as with a needle dispense mechanism, a jet dispense mechanism, a spray coating mechanism, an adhesive stamping mechanism, another type of mechanism, or combinations thereof. In the absence of active shaping mechanisms, the encapsulation material will form a shape that is determined by the encapsulation material surface tension, rheology, viscosity, and other characteristics.

[0028] As noted previously, the interface between first layer 102, second layer 106, and encapsulant 116, which corresponds to or tracks inner boundary 108 of window 107, may include imperfections and/or irregularities that result in cracks, gaps, or spaces. These cracks, gaps, or spaces may provide passageways through which fluid, such as ink from fluidic die 110, can seep or progress. As shown by the arrow A in Fig. 1A, this fluid progression may ultimately reach conductive path(s) 104 and/or bonded wires that form part of the electrical connection between first layer 102 and fluidic die 110, causing various types of damage to fluidic device 100.

[0029] Accordingly, in various examples, a planned void or cavity 114 may be created in first layer 102. In Fig. 1 a single void 114 is depicted on the right-hand side for illustrative purposes. However, in practice, multiple voids 114 may be applied, e.g., one near each comer of cover layer window 107. When encapsulant 116 is applied, it may be permeated into void 114 to form a plug (also referenced with 114). In some examples, encapsulant 116 may be applied on opposite surfaces of first !ayer 102, including the surface that is visible in the figures and a bottom surface facing away from the reader. In some such examples, encapsulant 116 may permeate into void 114 from the two opposite sides of first layer 102, As shown at arrow B of Fig, 1 A, void/plug 114 may block progression of fluid such as ink along inner boundary 108 of window 107.

[0030] Void 114 may have various shapes, such as the elongate shape depicted in Fig. 1A. In some such examples, the elongate void 114 may be oriented such that it is substantially perpendicular to inner boundary 108 of window 107. Void 114 may also come in various sizes. In some examples, void 114 may be between 50 and 400 μm wide, and between 300 and 900 μm long, such as between 350 and 450 μm long. These dimensions are not limiting, and other dimensions are contemplated.

[0031] Figs. 2A, 2B, and 2C schematically depict one stage of assembly of a fluidic device configured with selected aspects of the present disclosure. In Fig, 2A, first layer 102 once again takes the form of a circuit layer having conductive path(s) 104 etched or otherwise disposed on its surface. The conductive paths 104 shown in the Figures are for illustrative purposes, and are not meant to be limiting in any way.

[0032] First layer 102 also includes an opening 120 that may be included for a variety of purposes, such as accommodating a fluidic die. Cross-sectional lines B and C demonstrate perspectives from which cross sectional views 2B and 2C, respectively, are taken. These same cross-sectional lines will be used throughout Figs. 2A-6C, As indicated by the ellipses on other side of first layer 102, in some examples, first layer 102 may be part of a reel or sheet of multiple circuit layers 102 having the same or similar shapes.

[0033] In Figs. 2A-C, two planned voids 114 have been formed in (e.g., through) first layer 102. This may occur during manufacturing, e.g., at the same time opening 120 is created. Alternatively, voids 114 may be created or formed post manufacturing, e.g., using coherent Sight. Notably, voids 114 are at locations of first layer 102 that are selected to underlie an inner boundary of a window of a second, cover layer (not yet included in Figs. 2A-C) disposed on first layer 102. As noted previously, voids 114 may be positioned to receive a molded material such as encapsulant 116. In each void 114, the received encapsuiant may form a plug to block progression of fluid along the Inner boundary of the cover layer window. For the remainder of Figs. 3A-6C, the void 114 at right in Figs. 3A, 4A, 5A, and 6A will be referenced, but that description may be applicable to other voids 114 created in first layer 102.

[0034] Figs. 3A, 3B, and 3C schematically depict another stage of assembly of the same fluidic device. In Figs. 3A-C, a second, cover layer 106 has been disposed on top of (relative to the reader) first layer 102, which is why first layer 102 is not visible (although in practice, cover layer 106 may be clear, in which case the underlying first layer 102 would still be visible). As noted previously, cover layer 106 may be formed with various different materials, such as EVA. As shown best in Fig. 3C, void 114 is now covered on one side by cover layer 106.

[0035] Figs. 4A, 4B, and 4C schematically depict another stage of assembly of the same fluidic device. A window 107 has been created in cover layer 106 so that a portion of first layer 102 is once again visible in Fig. 4A. Window 107 defines an inner boundary 108 that is adjacent to void 114. For example, in Fig. 4A, void 114 is seen to cross inner boundary 108 substantially perpendicularly. In Fig. 4G, inner boundary 108 of window 107 can be seen to extend partially across void 114. In other examples (such as that depicted in Figs. 7A-C), void 114 may be cut in both cover layer 106 and first layer 102, in which case void 114 would be more or less aligned (e.g., on one side) with inner boundary 108 of window 107, [0036] Figs. 5A, SB, and 50 schematicaily depict another stage of assembly of the same fluidic device, in Figs. 5A-G, a fluidic die 110 has be disposed within window 107 and electrically coupied with conductive path(s) 104. if left exposed, this electrical coupling between fluidic die 110 and conductive path(s) 104 of first layer 102 may be vulnerable to whatever elements may be present in the environment, including but not limited to fluid such as ink that is manipulated by fluidic die 110.

[0037] Accordingly, and as shown in Figs. 6A-C, an encapsulant 116 is applied over the electrical coupling between fluidic die 110 and conductive path(s) 104. Notably, encapsulant 116 is also applied over ail or part of void 114. Consequently, encapsulant is permeated into void 114, as depicted best in Fig. 6C, to create a plug. This piug may halt or block progression of fluid such as ink towards conductive path(s) 104 and/or the electrical coupling between them and fluidic die 110, which may include bonded wire(s).

[0038] As also shown in Fig, SC, in some examples, two encapsuiants, 116 and 122, may be applied on opposite surfaces of first layer 102. In some such examples, these encapsuiants 116, 122 may Include the same materials as each other or different materials from each other. In addition to either or both encapsulant 116, 122 forming alt or part of the resulting piug, in some examples, they may form together during application and may bond and/or set together, e.g., as a unitary mass. This unitary mass may, in addition to blocking fluid as described previously, also strengthen the fluidic device as a whole, and/or may strengthen a force that holds encapsuiants 116 and 122 to each other and to first and second layer 102 and 106.

[0039] Figs. 7A~C depict an alternative to that assembly process demonstrated in Figs. 2A-6C, and are from perspectives similar to that of Figs. 20, 30, 40, 5C, and 60. Rather than creating a void 114 through first layer 102 before application of cover layer 106, the void 114 is created through both first and second layers 102, 106, after they are assembled with each other.

[0048] in Fig. 7 A, cover layer 106 has been disposed on first layer 102. This is similar to Figs. 3A-C, except no void 114 yet exists in either layer. In Fig. 7B, window 107 has been cut in cover layer 106, e.g., similar to Figs, 4A~C. in Fig, 7C, a void 114 has been created through both first layer 102 and cover layer 106, such that void 114 through each layer individually more or less spatially coincides, e.g., is flush, with void 114 through the other layer. Encapsulant (e.g., 116, 122) may then be applied as described previously.

[0041] Fig. 8 depicts an example method 800 for creating a plug to block against fluid progression towards a bonded wire of a fluidic device, where the bonded wire is connected to a fluidic die on a first end and to a conductive path of a circuit layer on a second end. Operations of method 800 may be reordered, omitted, or added.

[0042] At block 802, encapsulation [e.g., 116) may be applied over a bonded wire that electrically couples a fluid die (e.g,, 110) with a conductive path (e g., 104) of a circuit layer (e.g., 102). At block 804, the encapsulation may be permeated, e.g.. by its own viscosity and/or by being deliberately deposited, into a planned void (e.g., 114) in the circuit layer. As described previously, this may create a plug to block fluid progression along an interface between multiple layers of the fluidic device.

[0043] Fig. 9 schematically depicts a block diagram of a fluid ejection device 950 according to one example of the principles described herein. The fluid ejection device 950 includes an electronic controller 970 and prlnthead(s) 988 configured with selected aspects of the present disclosure. If fluid ejection device 950 is a color printer, then there may be multiple printheads 968, e.g., one each for cyan, magenta, yellow, and black (“CMYK”). The fluid ejection assembly 900 may be any example fluid ejection assembly described,

Illustrated, and/or contemplated by the present disclosure. As shown in Fig. 9, printhead 988 may include a fluidic device 100 that includes a fluidic die 110, encapsulant 116, and voids 114 that are filled with material (e.g., encapsulant 116) for form plugs that block fluid progression towards vulnerable components of fluidic device 100,

[0044] The electronic controller 970 may include a processor, firmware, and other electronics for communicating with and controlling integrated circuitry (not depicted) that in turn operates printhead 968 in order to eject fluid droplets in a precise manner. The electronic controller 970 receives data from a host system (not depicted), such as a computer. The data represents, for example, a document and/or file to be printed and forms a pri nt job that incl udes print job command(s) and/or command parameter(s). From the data, the electronic controller 970 defines a pattern of drops to eject which form characters, symbols, and/or other graphics or images.

[0045] in one example, the fluid ejection device 950 may be an inkjet printing device. In this example, the fluid ejection device 950 may further include a fluidly coupled jettabie materia! reservoir 972 fiuidiy coupled to printhead 968 and fluidic device 100 to supply jettabie material thereto.

[0046] A media transport assembly 974 may be included in the fluid ejection device 950 to provide media for the fluid ejection device 950 in order to create images on the media via ejection of the jettabie material. The fluid ejection device 950 may further include a power supply 976 to power the various electronic elements of the fluid ejection device 950.

[0047] Although described specifically throughout the entirety of the instant disclosure, representative examples of the present disclosure have utility over a wide range of applications, and the above discussion is not intended and should not be construed to be limiting, but is offered as an illustrative discussion of aspects of the disclosure.

Claims

CLAIMS What is claimed is:

1. A fiuidic device, comprising a cover layer with an inner boundary that defines a window through the cover layer; a circuit layer adjacent the cover layer, the circuit layer including a void that is adjacent the inner boundary of the window of the cover layer; a fluidic die disposed on the circuit layer within the window; and an encapsulant that overlays an electrical coupling between the fluidic die and a conductive path of the circuit layer, wherein the encapsulant permeates into the void to form a plug that blocks progression of fluid along the inner boundary towards the electrical coupling.

2. The fluidic device of claim 1 , wherein the void has an elongate shape that is substantially perpendicular to the inner boundary of the cover layer.

3. The fluidic device of claim 1 , wherein the encapsulant permeates into the void from two opposite sides of the circuit layer.

4. The fluidic device of claim 1 , wherein the void of the circuit layer crosses the inner boundary of the window of the cover layer,

5. The fluidic device of claim 1 , wherein the void of the circuit layer coincides spatially with another void of the cover layer.

6. The fluidic device of claim 1 , wherein the cover layer is constructed with ethylene vinyl acetate (“EVA").

7. The fluidic device of claim 1, wherein the void Is between 50 and 400 μm wide.

8. The fluidic device of claim 1 , wherein the void is between 300 and 900 μm tong.

9. The fluidic device of claim 1, wherein the void is between 350 and 450 μm long.

10. A method for creating a plug to block against fluid progression towards a bonded wire of a fluidic device, the bonded wire being connected to a fluidic die on a first end and to a conductive path of a circuit layer on a second end, the method comprising: applying encapsulation over the bonded wire; and permeating the encapsulation into a planned void in the circuit layer to create the plug to block progression of fluid towards the bonded wire.

11. The method of claim 10, comprising cutting the void into the circuit layer using coherent light

12. The method of claim 11 , wherein the cutting comprises cutting another void in a cover layer overlaying alt or part of the circuit layer.

13. The method of claim 10, comprising cutting a window into a cover layer overlaying all or part of the circuit layer so that an inner boundary of the window crosses the void in the circuit layer.

14. A circuit layer for use with a fluidic device, the circuit layer comprising a planned void through the circuit layer at a location of the circuit layer that is selected to underlie an inner boundary of a window of a cover layer disposed on the circuit layer, the void to receive a molded material that forms a plug to block progression of fluid along the inner boundary of the cover layer window.

15. The circuit layer of claim 14, wherein the planned void has an elongate shape.