WO2021201822A1

WO2021201822A1 - Fluid ejection assemblies

Info

Publication number: WO2021201822A1
Application number: PCT/US2020/025680
Authority: WO
Inventors: Kenneth James Faase; Garrett E. Clark; Ron Tuttnauer; Teressa L. Roth
Original assignee: Hewlett Packard Development Co LP
Current assignee: Hewlett Packard Development Co LP
Priority date: 2020-03-30
Filing date: 2020-03-30
Publication date: 2021-10-07
Anticipated expiration: 2022-09-30

Abstract

Examples of fluid ejection assemblies are described herein. In some examples, a fluid ejection assembly may include a circuit board. In some examples, the fluid ejection assembly includes a fluidic die positioned adjacent to the circuit board. In some examples, the fluidic die is distanced from the circuit board. In some examples, the input side of the fluidic die is disposed coplanarly with a back of the circuit board. In some examples, the fluid ejection assembly includes an electrical interconnect coupled between an output side of the fluidic die and the circuit board. In some examples, the fluid ejection assembly includes a monolithic overmolding covering the electrical interconnect and covering a face of the circuit board.

Description

FLUID EJECTION ASSEMBLIES

BACKGROUND

[0001] Some types of printing utilize liquid. For example, some types of printing extrude liquid onto media or material to produce a printed product (e.g., two-dimensional (2D) printed content, three-dimensional (3D) printed objects). In some examples, a fluidic die may be utilized to extrude printing fluids, such as ink, onto paper to print text and/or images. In some examples, a fluidic die may be utilized to extrude fusing agent onto powder in order to form a 3D printed object.

BRIEF DESCRIPTION OF THE DRAWINGS

[0002] Figure 1 is a diagram illustrating an example of a fluid ejection assembly;

[0003] Figure 2 is a diagram illustrating an example of a cross-sectional view of a portion of a fluid ejection assembly;

[0004] Figure 3A is a diagram illustrating an example of a cross-sectional view of a portion of a fluid ejection assembly;

[0005] Figure 3B is a diagram illustrating an example of a cross-sectional view of a portion of a fluid ejection assembly;

[0006] Figure 3C is a diagram illustrating an example of a cross-sectional view of a portion of a fluid ejection assembly;

[0007] Figure 3D is a diagram illustrating an example of a cross-sectional view of a portion of a fluid ejection assembly; [0008] Figure 3E is a diagram illustrating an example of a cross-sectional view of a portion of a fluid ejection assembly;

[0009] Figure 3F is a diagram illustrating an example of a cross-sectional view of a portion of a fluid ejection assembly;

[0010] Figure 4 is a flow diagram illustrating one example of a method for manufacturing a fluid ejection assembly;

[0011] Figure 5A is a diagram illustrating a perspective view of a circuit board;

[0012] Figure 5B is a diagram illustrating a perspective view of the circuit board described in relation to Figure 5A;

[0013] Figure 5C is a diagram illustrating a perspective view of the fluidic dies described in relation to Figures 5A-B;

[0014] Figure 5D is a diagram illustrating a perspective view of an apparatus; [0015] Figure 5E is a diagram illustrating a cross-sectional perspective view of the apparatus described in relation to Figure 5D;

[0016] Figure 6A illustrates an example of printing with a 2-millimeter (mm) die-to-media spacing; and

[0017] Figure 6B illustrates an example of printing with a 3-mm die-to-media spacing.

DETAILED DESCRIPTION

[0018] A fluidic die is circuitry for extruding fluid. For example, a fluidic die may include channels, nozzles, and/or electronic circuitry (e.g., resistors, heaters, transducers, etc.) to extrude fluid onto media (e.g., paper, material, etc.) for printing (e.g., two-dimensional (2D) printing and/or three-dimensional (3D) printing). In some examples, a fluidic die may be fabricated from semiconductor material, such as silicon (Si). In some examples, a fluidic die may be positioned relative to a surface (e.g., a surface of a fluid ejection assembly, fluid ejection device, etc.). A surface with which the fluidic die may be positioned may be referred to as a headland. For instance, a fluidic die may be positioned above the surface (e.g., headland), flush with the surface (e.g., headland), or below the surface (e.g., headland).

[0019] One issue that may arise with fluidic dies is a media-head crash. A media-head crash is a collision or strike between media (e.g., paper, material, etc.) and a fluidic die. Media-head crashes may damage a fluidic die. In some examples, media-head crashes may be more likely to occur with fluidic dies that are more exposed relative to the surface.

[0020] In some examples, tradeoffs may exist between media-head crash likelihood and print quality and/or between media-head crash likelihood and serviceability. For instance, closer positioning of a fluidic die to media may provide a shorter drop flight path, higher drop placement precision on the media, and/or higher print quality, but may increase a likelihood of media-head crashes and/or fluidic die damage. In some examples, more prominent positioning of a fluidic die relative to the surface (e.g., headland) may provide greater serviceability, but may increase the likelihood of media-head crashes and/or fluidic die damage.

[0021] Some of the examples described herein may improve protection of the fluidic die from media-head crashes, may improve serviceability (e.g., access to clean the fluidic die) and/or may improve die-to-media spacing for improved print quality. Some of the examples described herein may utilize epoxy mold compound (EMC). In some examples, EMC may provide improved fluid (e.g., printing fluid, print liquid, ink, agent, etc.) erosion resistance, which may allow for less protection thickness relative to some adhesive approaches. In some examples, EMC molding may provide improved control of positional precision, which may allow for less protection thickness relative to some adhesive approaches.

[0022] Throughout the drawings, identical reference numbers may designate similar, but not necessarily identical, elements. Similar numbers may indicate similar elements. When an element is referred to without a reference number, this may refer to the element generally, without necessary limitation to any particular figure. The figures are not necessarily to scale, and the size of some parts may be exaggerated to more clearly illustrate the example shown. Moreover, the drawings provide examples and/or implementations in accordance with the description; however, the description is not limited to the examples and/or implementations provided in the drawings.

[0023] Figure 1 is a diagram illustrating an example of a fluid ejection assembly 100. The fluid ejection assembly 100 may be utilized to extrude fluid (e.g., printing fluid, print liquid, ink, agent, etc.). For example, the fluid ejection assembly 100 may be a portion of (and/or may be attached to) a fluid ejection device, print liquid supply, print liquid container, fluid reservoir, etc. In some examples, the fluid ejection assembly 100 may be designed to interface with a host device. A host device is a device that uses and/or applies fluid. Examples of a host device include printers, inkjet printers, 3D printers, etc.

[0024] The fluid ejection assembly 100 may include a circuit board 102. A circuit board is a structure that includes circuitry. Examples of the circuit board 102 may include printed circuit boards, flexible circuitry, a substrate with a conductive element or elements, a lead frame, a trace or traces, a wire or wires, etc. For example, the circuit board 102 may include metal traces on a substrate and/or embedded in non-conductive material.

[0025] The fluid ejection assembly 100 may include a fluidic die 106. In some examples, the fluidic die 106 is positioned adjacent to the circuit board 102. In some examples, the fluidic die 106 may be distanced from the circuit board 102. For example, the fluidic die 106 may be positioned adjacent to the circuit board 102 without contacting the circuit board 102. For instance, the fluidic die 106 may be positioned adjacent to the circuit board 102 and separated by a distance 104. In some examples, a transverse gap or gaps may separate the fluidic die 106 from the circuit board 102. The fluidic die 106 may be shaped in a variety of shapes. For example, the fluidic die 106 may be rectangular or irregularly shaped. The circuit board 102 may be shaped in a variety of shapes. For example, the circuit board 102 may be rectangular or irregularly shaped. In some examples, the circuit board 102 may be positioned adjacent to an edge of the fluidic die 106 and/or may be positioned partially or completely around the fluidic die 106. [0026] The fluidic die 106 may include a nozzle or nozzles, where an output side of the fluidic die 106 is a side from which a nozzle is to extrude fluid. For instance, a front side of the fluidic die 106 (a side that is in view in Figure 1 ) may be an output side of the fluidic die 106. The fluidic die 106 may include an input side. An input side of the fluidic die 106 is a side from which fluid (e.g., printing fluid, print liquid, ink, agent, etc.) is to be input. For example, an input side may include an opening or openings for a fluid feed channel or channels. An input side of the fluidic die 106 may be opposite from the output side. The input side (or back side) of the fluidic die 106 is not in view in Figure 1.

[0027] In some examples, the circuit board 102 may include a face. A face of the circuit board 102 may be a side of the circuit board 102 that corresponds to (e.g., faces a similar direction as) the output side of the fluidic die 106 and/or that includes a connection point for the electrical interconnect 108. In some examples, the circuit board 102 may include a back side. A back side of the circuit board 102 may be a side that is opposite from the face of the circuit board 102. For example, a back side of the circuit board 102 may correspond to (e.g., faces a similar direction as) an input side of the fluidic die 106.

[0028] In some examples, the input side of the fluidic die 106 is disposed coplanarly with a back of the circuit board 102. As used herein, the term “coplanar” and variations thereof may mean being situated in a same geometrical plane. For example, all or a portion of the input side of the fluidic die 106 and/or all or a portion of the back of the circuit board 102 may be situated in a geometrical plane. In some examples, the input side of the fluidic die 106 and/or the back of the circuit board 102 may or may not be exactly flat or planar while being disposed coplanarly with each other. In some examples, the input side of the fluidic die 106 and the back of the circuit board 102 may be disposed coplanarly as a result of being placed on an approximately planar surface (e.g., substrate, sacrificial substrate, etc.) during manufacturing.

[0029] In some examples, the fluidic die 106 may be positioned adjacent to the circuit board 102 on a side or sides (e.g., vertical sides, non-input and/or non-output sides) of the fluidic die. For example, the fluidic die 106 may be positioned adjacent to the circuit board 102 and/or distanced from the circuit board 102 on a side or sides of the fluidic die 106.

[0030] In some examples, the circuit board 102 may include a slot. A slot is an opening, window, or hole of a structure. A slot may be partially or completely enclosed by the structure in a dimension or dimensions. In some examples, the circuit board may completely enclose the slot in two dimensions (e.g., transverse dimensions). In other examples, a circuit board may enclose (e.g., border, limit, surround) a slot on a side and/or a portion of a side. For example, a circuit board may enclose a slot on a portion of one side, on a side, and/or on multiple sides. For instance, a circuit board may enclose or surround a slot on three sides and a portion of a fourth side. A slot may be empty, partially filled, or completely filled. Examples of slots are illustrated in Figure 5A.

[0031] In some examples, a fluid ejection assembly may include a fluidic die positioned within a slot. A fluidic die positioned within a slot of a circuit board may be an example of a fluidic die positioned adjacent to a circuit board. In some examples, a fluidic die may be distanced from the circuit board within the slot. For example, the fluidic die may be positioned within the slot without contacting the circuit board. In some examples, a transverse gap or gaps may separate the fluidic die from the circuit board.

[0032] The fluid ejection assembly 100 may include an electrical interconnect 108 coupled between an output side of the fluidic die 106 and the circuit board 102. An electrical interconnect is an electrical connection between elements. Examples of an electrical interconnect may include a wire (e.g., metal wire, gold wire, copper wire, etc.), trace, metal coupling, etc. The electrical interconnect 108 may electrically connect the circuit board 102 to the fluidic die 106. In some examples, multiple electrical interconnects may be coupled between a fluidic die and a circuit board. For example, electrical interconnects may be utilized to send signals to a fluidic die to control fluid extrusion. For instance, electrical interconnects may carry signals to resistors, heaters, and/or transducers of a fluidic die, which may cause fluid to be extruded from an output side of the fluidic die. [0033] In some examples, the fluid ejection assembly 100 may include a monolithic overmolding 110. As used herein, the term “monolithic” may denote a unitary material. For example, the monolithic overmolding 110 may be manufactured from one material (e.g., compound material, EMC, etc.) and/or may be manufactured in a single molding procedure. For example, the monolithic overmolding 110 may be manufactured with an application of liquid epoxy molding compound, which may harden and/or cure with or without the application of heat. In some examples, the monolithic overmolding 110 may not be manufactured in separate stages (e.g., separate applications) and/or may not be manufactured with multiple curing periods. For instance, the monolithic overmolding 110 may not be manufactured in separate portions that are applied in different time periods.

[0034] In some examples, the monolithic overmolding 110 may cover the electrical interconnect 108, may cover a face of the circuit board 102, and/or may fill all or a portion or all of the distance 104 between the fluidic die 106 and the circuit board 102. For example, the monolithic overmolding 110 may be molded around, may cover, and/or may protect the electrical interconnect 108. In some examples, the electrical interconnect 108 may not be covered, shielded, and/or protected with material other than the monolithic overmolding 110. For instance, the electrical interconnect 108 may not be covered with a separate sealant, protectant, adhesive, layer, material, and/or separate application of EMC.

[0035] In some examples, a monolithic overmolding may cover a portion of, or an entire face of, a circuit board. For example, the monolithic overmolding 110 may cover a face of the circuit board 102 that is a front face of the circuit board 102, that faces a nozzle output direction of the fluidic die 106, and/or that is parallel to a nozzle output plane of the fluidic die. In some examples, the monolithic overmolding 110 may not cover a back side of the circuit board 102 and/or fluidic die 106.

[0036] In some examples, a monolithic overmolding may fill all or a portion of a distance and/or slot between a fluidic die and a circuit board. For instance, the monolithic overmolding 110 may fill all or a portion of the distance 104 (e.g., a transverse gap) between the fluidic die 106 and the circuit board 102. In some examples, a monolithic overmolding may fill all or a portion of a slot that is not filled by a fluidic die. In some examples, the monolithic overmolding 110 may form a stepped structure in between the fluidic die 106 and the circuit board 102.

[0037] In some examples, a material that is separate from the monolithic overmolding may fill all or a portion of a distance (e.g., a gap, a slot) between a fluidic die and a circuit board. For example, material of the monolithic overmolding may cover, support, and/or protect an area around an electrical interconnect or interconnects, and a second material may fill another area (e.g., in the distance 104 of a gap between circuit board 102 and the fluidic die 106). In some examples, a combination of a monolithic overmolding and a second material may fill a gap between a fluidic die and a circuit board.

[0038] Figure 2 is a diagram illustrating an example of a cross-sectional view of a portion of a fluid ejection assembly 200. The fluid ejection assembly 200 described in relation to Figure 2 may be an example of the fluid ejection assembly 100 described in relation to Figure 1.

[0039] In the example illustrated in Figure 2, the fluid ejection assembly 200 includes a circuit board 218. The fluid ejection assembly 200 also includes a fluidic die 212. The fluidic die 212 may include a first portion 214 that includes fluid nozzle(s) and/or firing chamber(s). The fluidic die 212 may also include a second portion 220 that includes fluid feed channels 222a-222c. In some examples, a fluidic die may be a silicon (Si) die that includes fluid nozzle(s), firing chamber(s) and/or fluid feed channel(s). In the example illustrated in Figure 2, the upper side of the first portion 214 and/or the upper side of the second portion 220 may be included in an output side 215 of the fluidic die 212. A nozzle output side of the fluidic die 212 may include a side of the first portion 214 (e.g., upper side, outward facing side) that includes a nozzle opening or openings. An input side 221 of the fluidic die 212 may be opposite from the output side 215 of the fluidic die 212. For example, the input side 221 of the fluidic die 212 may include openings for fluid feed channels 222a-c. In some examples, the input side 221 may be parallel to the output side 215 of the fluidic die 212.

[0040] The fluidic die 212 may be positioned adjacent to the circuit board 218. The fluidic die 212 may be distanced from the circuit board 218. For example, a transverse gap 219 between an outer edge of the fluidic die 212 (e.g., second portion 220) and an inner edge of the circuit board 218 may separate the fluidic die 212 and the circuit board 218.

[0041] The fluid ejection assembly 200 may include an electrical interconnect 224 coupled between an output side 215 of the fluidic die 212 and the circuit board 218. For example, the electrical interconnect 224 may be coupled to the fluidic die 212 on an output side 215 of the fluidic die 212 (e.g., on top of the second portion 220 and alongside the first portion 214 of the fluidic die 212). In some examples, the electrical interconnect 224 may be coupled to a first side 217 of the circuit board 218 (e.g., a face, a top side, or output facing side of the circuit board 218). The input side 221 of the fluidic die 212 may be disposed coplanarly with a second side 223 (e.g., a back, a bottom side) of the circuit board 218. For example, the second side 223 of the circuit board 218 (that is opposite to the first side 217, for instance) may be disposed flush to (e.g., approximately coplanar to) an input side 221 (e.g., a bottom side) of the fluidic die 212 that is opposite to the output side 215.

[0042] In some examples, the input side 221 (e.g., bottom side, bottom plane, plane opposite to the output side 215, etc.) of the fluidic die 212 may be in contact with fluid of a fluid ejection device. For instance, the input side 221 of the fluidic die 212 may be in contact with (e.g., exposed to) fluid (e.g., printing fluid, print liquid, ink, agent, etc.) after the fluid ejection assembly 200 is incorporated into and/or attached to a fluid ejection device. In some examples, the input side 221 of the fluidic die 212 may be in contact with fluid of a fluid ejection device without intervening material and/or support. For instance, the input side 221 of the fluidic die 212 may not be in contact with a support, carrier, and/or circuit board in some examples.

[0043] In some examples, the fluid ejection assembly 200 may include a monolithic overmolding 216 covering the electrical interconnect 224, covering a face (e.g., first side 217, output-facing side, top side) of the circuit board 218, and/or filling all or a portion of the distance between the fluidic die 212 and the circuit board 218. For instance, the monolithic overmolding 216 may be molded around the electrical interconnect 224, over a face of the circuit board 218, and in the transverse gap 219 between the fluidic die 212 and the circuit board 218. For instance, the monolithic overmolding 216 may include a stepped structure between the fluidic die 212 and the circuit board 218. The stepped structure may fill the transverse gap 219. In some examples, an end of the stepped structure may be flush with (e.g., approximately coplanar to) the back of the circuit board 218 and/or the input side 221 of the fluidic die 212.

[0044] Figure 3A is a diagram illustrating an example of a cross-sectional view of a portion of a fluid ejection assembly. The fluid ejection assembly described in relation to Figure 3A may be an example of the fluid ejection assembly 100 described in relation to Figure 1. In some examples, a component or components of the fluid ejection assembly described in relation to Figure 3A may be similar to a component or components of the fluid ejection assembly 200 described in relation to Figure 2.

[0045] In the example illustrated in Figure 3A, the fluid ejection assembly includes a circuit board 324a, a fluidic die 334a (that includes a first portion 330a and a second portion 332a), an electrical interconnect 326a, and a monolithic overmolding 328a. Some examples of the techniques described herein may enable controlling a headland-to-die interface angle 336. For example, manufacturing of the monolithic overmolding may be controlled to result in a target headland-to-die interface angle 336. In some examples, the headland-to-die interface angle 336 may be controlled between 0 degrees (e.g., flush) and 180 degrees.

[0046] Figure 3B is a diagram illustrating an example of a cross-sectional view of a portion of a fluid ejection assembly. The fluid ejection assembly described in relation to Figure 3B may be an example of the fluid ejection assembly 100 described in relation to Figure 1. In some examples, a component or components of the fluid ejection assembly described in relation to Figure 3B may be similar to a component or components of the fluid ejection assembly 200 described in relation to Figure 2.

[0047] In the example illustrated in Figure 3B, the fluid ejection assembly includes a circuit board 324b, a fluidic die 334b (that includes a first portion 330b and a second portion 332b), an electrical interconnect 326b, and a monolithic overmolding 328b. Some examples of the techniques described herein may enable controlling a headland-to-die interface position 338. For example, manufacturing of the monolithic overmolding 328b may be controlled to result in a target headland-to-die interface position 338. In some examples, the headland-to-die interface position 338 may be controlled to cover a target amount of the fluidic die 334b (e.g., a target amount of the first portion 330b of the fluidic die 334b).

[0048] Figure 3C is a diagram illustrating an example of a cross-sectional view of a portion of a fluid ejection assembly. The fluid ejection assembly described in relation to Figure 3C may be an example of the fluid ejection assembly 100 described in relation to Figure 1. In some examples, a component or components of the fluid ejection assembly described in relation to Figure 3C may be similar to a component or components of the fluid ejection assembly 200 described in relation to Figure 2.

[0049] In the example illustrated in Figure 3C, the fluid ejection assembly includes a circuit board 324c, a fluidic die 334c (that includes a first portion 330c and a second portion 332c), an electrical interconnect 326c, and a monolithic overmolding 328c. Some examples of the techniques described herein may enable controlling a fluidic die 334c recession depth in the headland (e.g., relative to the monolithic overmolding 328c). For instance, the recession depth may be within a range (e.g., 0-300 micrometers (pm), 150 pm, etc.). For example, manufacturing of the monolithic overmolding 328c may be controlled to result in a target fluidic die 334c depth. In some examples, the fluidic die 334c depth may be controlled to be flush with (e.g., 0 depth relative to) a surface 340 of the monolithic overmolding 328c. For instance, a nozzle output side of the fluidic die 334c (e.g., a nozzle output side of the first portion 330c of the fluidic die 334c) may be flush (e.g., approximately coplanar) to a surface 340 of the monolithic overmolding 328c (e.g., flush with an output side, front side, or headland surface of the monolithic overmolding 328c). In some examples, a nozzle output side of a fluidic die (e.g., a nozzle output side of a first portion of the fluidic die) may be recessed (e.g., below) relative to a surface of the monolithic overmolding (e.g., below an output side, front side, or headland surface of the monolithic overmolding). Examples of a recessed fluidic die are illustrated in Figures 2, 3A, 3B, and 3D.

[0050] Figure 3D is a diagram illustrating an example of a cross-sectional view of a portion of a fluid ejection assembly. The fluid ejection assembly described in relation to Figure 3D may be an example of the fluid ejection assembly 100 described in relation to Figure 1. In some examples, a component or components of the fluid ejection assembly described in relation to Figure 3D may be similar to a component or components of the fluid ejection assembly 200 described in relation to Figure 2.

[0051] In the example illustrated in Figure 3D, the fluid ejection assembly includes a circuit board 324d, a fluidic die 334d (that includes a first portion 330d and a second portion 332d), an electrical interconnect 326d, and a monolithic overmolding 328d. Some examples of the techniques described herein may enable providing additional headland surface topography. For example, manufacturing of the monolithic overmolding 328d may be controlled to provide a mesa 342 or mesas. A mesa 342 or mesas may provide additional fluidic die 334d protection from media crashes.

[0052] Figure 3E is a diagram illustrating an example of a cross-sectional view of a portion of a fluid ejection assembly. The fluid ejection assembly described in relation to Figure 3E may be an example of the fluid ejection assembly 100 described in relation to Figure 1. In some examples, a component or components of the fluid ejection assembly described in relation to Figure 3E may be similar to a component or components of the fluid ejection assembly 200 described in relation to Figure 2.

[0053] In the example illustrated in Figure 3E, the fluid ejection assembly includes a circuit board 324e, a fluidic die 334e (that includes a first portion 330e and a second portion 332e), an electrical interconnect 326e, and a monolithic overmolding 328e. Some examples of the techniques described herein may enable covering the electrical interconnect 326e with a protruding structure 344. For instance, a portion of the electrical interconnect 326e may be disposed within a protruding structure 344 of the monolithic overmolding 328e. In some examples, a surface of the monolithic overmolding 328e (e.g., headland) may be flush with the first portion 330e of the fluidic die 334e except over the electrical interconnect 326e.

[0054] Figure 3F is a diagram illustrating an example of a cross-sectional view of a portion of a fluid ejection assembly. The fluid ejection assembly described in relation to Figure 3F may be an example of the fluid ejection assembly 100 described in relation to Figure 1. In some examples, a component or components of the fluid ejection assembly described in relation to Figure 3F may be similar to a component or components of the fluid ejection assembly 200 described in relation to Figure 2.

[0055] In the example illustrated in Figure 3F, the fluid ejection assembly includes a circuit board 324f, a fluidic die 334f (that includes a first portion 330f and a second portion 332f), an electrical interconnect 326f, and a monolithic overmolding 328f. Some examples of the techniques described herein may provide a multi-level headland surface. In some examples, a first edge of the fluidic die 334f (e.g., first edge of a first portion 330f of the fluidic die 334f) may be flush with a first level 348 of the monolithic overmolding 328f and a second edge of the fluidic die 334f (e.g., a second edge of a first portion 330f of the fluidic die 334f) may be recessed and/or covered relative to a second level 346 of the monolithic overmolding 328f.

[0056] Some examples of the techniques described herein may provide a controlled molded surface (e.g., monolithic overmolding) that may provide a benefit or benefits for capping of a fluid ejection assembly. For example, some surfaces of the fluid ejection assembly may have a discontinuous surface between encap beads and a headland surface, where the capping may be achieved on the headland surface. In some examples of the techniques described herein, a monolithic overmolding may or may not include an encap mesa or mesas. Some examples of the monolithic overmolding may provide a larger surface area per fluidic die than other approaches.

[0057] Some examples of the fluid ejection assemblies described herein may include a fluidic die or fluidic dies and a circuit board(s) electronically packaged with controlled molded surfaces. Some examples of the fluid ejection assemblies described herein may address issues with media-die crashes, and/or may offer benefits for print quality, servicing, and/or capping. For instance, some examples of the fluid ejection assemblies described herein may improve (e.g., reduce) die-to-media spacing, which may improve print quality. [0058] Figure 4 is a flow diagram illustrating one example of a method 400 for manufacturing a fluid ejection assembly. In some examples, the method 400 may be performed by an assembly machine or machines. In some examples, the method 400 may be performed to produce a fluid ejection assembly or fluid ejection assemblies described in relation to Figures 1-3F. The method 400 may include placing 402 a circuit board on a surface (e.g., substrate, sacrificial substrate, etc.). For example, the circuit board may be placed on a surface for manufacturing, on a substrate, or on a sacrificial substrate. A sacrificial substrate is a substrate to be removed. For example, a sacrificial substrate may be utilized to support components of a fluid ejection assembly during manufacturing and may be removed such that the sacrificial substrate is not included in the fluid ejection assembly after manufacturing. In some examples, a sacrificial substrate may have an adhesive surface. For example, the circuit board and/or other component(s) may adhere to the adhesive surface of the sacrificial substrate when placed on the sacrificial substrate. In some examples, an assembly machine may place 402 the circuit board on the sacrificial substrate.

[0059] The method 400 may include placing 404 a fluidic die on the surface adjacent to the circuit board. For example, an assembly machine may place the fluidic die on the surface next to the circuit board. An input side of the fluidic die and a back of the circuit board may be aligned, flush, and/or coplanar on the surface. The fluidic die may be distanced from the circuit board. For example, the fluidic die may be placed such that there is a gap between the fluidic die and the circuit board (e.g., such that the fluidic die is not in direct contact with the circuit board). In some examples, the fluidic die may be placed on the surface within a slot of the circuit board.

[0060] The method 400 may include connecting 406 an electrical interconnect between an output side of the fluidic die and the circuit board. For example, an electrical interconnect may be bonded (e.g., gold ball bonded), welded, and/or soldered to an output side of the fluidic die (e.g., to a connecting pad or trace of the fluidic die) and/or to the circuit board (e.g., to a connecting pad or trace of the circuit board). Connecting 406 the electrical interconnect between the fluidic die and the circuit board may complete a fluidic die (e.g., silicon die) and circuit board circuit in some examples.

[0061] The method 400 may include overmolding 408 the electrical interconnect and a face of the circuit board. In some examples, the method 400 may include overmolding all or a portion of the distance between the fluidic die and the circuit board. For example, an assembly machine may overmold 408 the electrical interconnect, a face of the circuit board, and/or the gap between the fluidic die and the circuit board with epoxy mold compound. Overmolding 408 may include applying, injecting, and/or curing the epoxy mold compound. [0062] In some examples, the surface may be a sacrificial substrate and the method 400 may include removing the sacrificial substrate from the circuit board and the fluidic die. For example, the sacrificial substrate may be peeled and/or dissolved from the circuit board and the fluidic die.

[0063] In some examples, the method 400 may include removing a fluid ejection assembly from an overmolded sheet. For example, overmolding 408 may include forming an overmolded sheet that extends beyond the target geometry of the fluid ejection assembly. Removing the fluid ejection assembly from the overmolded sheet may include singulating, cutting, punching, and/or slicing the fluid ejection assembly from the overmolded sheet. The fluid ejection assembly may include the fluidic die, the circuit board, the electrical interconnect, and an overmolded shape. The fluidic die may be flush to (e.g., in plane with) a surface of the overmolded shape (e.g., monolithic overmolding or headland) in some examples. [0064] Figure 5A is a diagram illustrating a perspective view of a circuit board 556. The circuit board 556 described in relation to Figure 5A may be an example of a circuit board or circuit boards described in relation to any of Figures 1 -4. The circuit board 556 may include windows 554a-d. The windows 554a-d may be examples of a slot or slots described in relation to any of Figures 1 or 4. [0065] The circuit board 556 may be placed on a sacrificial substrate 550. For example, the circuit board 556 may adhere to the sacrificial substrate 550 when placed thereon. Fluidic dies 552a-d may be placed (e.g., disposed) within the windows 554a-d of the circuit board 556. Placing the fluidic dies 552a-d within the windows 554a-d may be an example of placing a fluidic die adjacent to a circuit board. Transverse gaps between outer edges of the fluidic dies 552a-d and inner edges of the windows 554a-d may separate the fluidic dies 552a-d and the circuit board 556. As illustrated in Figure 5A, a window 554a (or slot, for instance) may surround a first edge, a second edge, a third edge, and a portion of a fourth edge of a fluidic die 552a. As illustrated in Figure 5A, a window 554b (or slot, for instance) may surround a first edge, a second edge, a third edge, and a fourth edge of a fluidic die 552b. Four windows 554a-d and fluidic dies 552a-d are illustrated in Figure 5A. In other examples, a different number of windows and/or fluidic dies may be implemented. In some examples, the electrical circuit board 556 and/or fluidic dies 552a-d may be placed as part of the method 400 described in relation to Figure 4.

[0066] Figure 5B is a diagram illustrating a perspective view of the circuit board 556 described in relation to Figure 5A. In this example, electrical interconnects 558a-d, 560a-d are connected between the fluidic dies 552a-d and the circuit board 556. The electrical interconnects 558a-d, 560a-d described in relation to Figure 5B may be an example of an electrical interconnect or electrical interconnects described in relation to any of Figures 1- 4. In some examples, the electrical interconnects 558a-d, 560a-d may be wires bridging the gaps between output sides of the fluidic dies 552a-d and a front of the circuit board 556. In some examples, input sides of the fluidic dies 552a-d may be aligned with a back of the circuit board 556. The alignment may occur due to the placement on the sacrificial substrate 550 in some examples. In some examples, the electrical interconnects 558a-d, 560a-d may be connected as part of the method 400 described in relation to Figure 4.

[0067] Figure 5C is a diagram illustrating a perspective view of the fluidic dies 552a-d described in relation to Figures 5A-B. In this example, the circuit board 556, electrical interconnects 558a-d, 560a-d, and/or sacrificial substrate 550 are overmolded to form a monolithic overmolding 562. The monolithic overmolding 562 may be an example of a monolithic overmolding or monolithic overmoldings described in relation to any of Figures 1-4. In some examples, the monolithic overmolding 562 may seal the electrical interconnects 558a-d, 560a-d (e.g., wires) and/or may be disposed in the gaps between the outer edges of the fluidic dies 562a-d and the circuit board 556. In some examples, the monolithic overmolding 562 may be molded as part of the method 400 described in relation to Figure 4. In some examples, molding the monolithic overmolding 562 may produce an overmolded sheet. In some examples, the monolithic overmolding 562 may cover a front of the circuit board 556 and not a back of the circuit board 556 (due to the sacrificial substrate 550, for example). In some examples, the sacrificial substrate 550 may be removed (after the monolithic overmolding 562 is formed, for example).

[0068] Figure 5D is a diagram illustrating a perspective view of an apparatus 564. The apparatus 564 may be an example of a fluid ejection assembly or fluid ejection assemblies described in relation to any of Figures 1-4. In some examples, the apparatus 564 may be removed (e.g., singulated, cut, sliced, punched, etc.) from the overmolded sheet as part of the method 400 described in relation to Figure 4.

[0069] Figure 5E is a diagram illustrating a cross-sectional perspective view of the apparatus 564 described in relation to Figure 5D. The apparatus 564 may be an example of a fluid ejection assembly or fluid ejection assemblies described in relation to any of Figures 1-4. Figure 5E illustrates fluidic dies 552a-c and the circuit board 556 in the apparatus 564. Figure 5E also illustrates a transverse gap or gaps 566 between outer edges of the fluidic die 552c and inner edges of a window. The monolithic overmolding may fill the gap(s) 566. Examples of fluid feed channels 570 are also illustrated in Figure 5E. [0070] In some examples, a fluid ejection device (e.g., a print module) may include the apparatus 564. A fluid ejection device is a device for printing fluid onto media. For example, a fluid ejection device may include a fluid reservoir or reservoirs (e.g., printing fluid container(s), ink container(s)) or a fluid supply or supplies and the apparatus 564. For instance, a fluid supply or fluid supplies (e.g., fluid delivery structure(s), channel(s), tube(s), fluid reservoir(s), etc.) may be attached to a back side (e.g., input side) of a fluidic die or dies 552a-d. The fluid supply(ies) of the fluid ejection device may provide fluid (e.g., printing fluid, ink, print liquid, etc.) to the fluidic dies 552a-d, which may extrude or eject the fluid onto media when in operation. In some examples, a fluid ejection device may be integrated into, and/or may be a removable (e.g., replaceable) component of a printer.

[0071] Figure 6A illustrates an example of printing with a 2-millimeter (mm) die-to-media spacing. Some examples of the fluid ejection assemblies, apparatus, and/or methods described herein may provide a benefit of improved print quality. For instance, some examples may enable disposing a fluidic die at or near a headland surface, which may enable a closer die-to-media spacing, thereby improving print quality.

[0072] Figure 6B illustrates an example of printing with a 3-mm die-to-media spacing. As illustrated in Figure 6B, print quality may decline as die-to-media spacing increases. For instance, some examples of the fluid ejection assemblies, apparatus, and/or methods described herein may enable a closer die-to-media spacing, which may improve print quality as illustrated in Figure 6A.

[0073] As used herein, the term “and/or” may mean an item or items. For example, the phrase “A, B, and/or C” may mean any of: A (without B and C), B (without A and C), C (without A and B), A and B (but not C), B and C (but not A), A and C (but not B), or all of A, B, and C.

[0074] While various examples of techniques and structures are described herein, the techniques and structures are not limited to the examples. Variations of the examples described herein may be implemented within the scope of the disclosure. For example, operations, functions, aspects, or elements of the examples described herein may be omitted or combined.

Claims

1. A fluid ejection assembly, comprising: a circuit board; a fluidic die positioned adjacent to the circuit board, wherein the fluidic die is distanced from the circuit board, and wherein an input side of the fluidic die is disposed coplanarly with a back of the circuit board; an electrical interconnect coupled between an output side of the fluidic die and the circuit board; and a monolithic overmolding covering the electrical interconnect and covering a face of the circuit board.

2. The fluid ejection assembly of claim 1 , wherein the electrical interconnect is coupled to a first side of the circuit board.

3. The fluid ejection assembly of claim 2, wherein the input side of the fluidic die comprises openings for fluid feed channels.

4. The fluid ejection assembly of claim 1 , wherein a nozzle output side of the fluidic die is flush to a surface of the monolithic overmolding.

5. The fluid ejection assembly of claim 1 , wherein a nozzle output side of the fluidic die is recessed relative to a surface of the monolithic overmolding.

6. The fluid ejection assembly of claim 1 , wherein a portion of the electrical interconnect is disposed within a protruding structure of the monolithic overmolding.

7. The fluid ejection assembly of claim 1 , wherein a first edge of the fluidic die is flush with a first level of the monolithic overmolding and wherein a second edge of the fluidic die is recessed relative to a second level of the monolithic overmolding.

8. The fluid ejection assembly of claim 1 , wherein an input side of the fluidic die is in contact with fluid of a fluid ejection device.

9. The fluid ejection assembly of claim 1 , wherein the circuit board includes a slot, and wherein the slot surrounds a first edge of the fluidic die, a second edge of the fluidic die, a third edge of the fluidic die, and a portion of a fourth edge of the fluidic die.

10. The fluid ejection assembly of claim 1 , wherein the monolithic overmolding fills all or a portion of a distance between the fluidic die and the circuit board.

11. A fluid ejection device, comprising: fluidic dies disposed within windows of a circuit board, wherein transverse gaps between outer edges of the fluidic dies and inner edges of the windows separate the fluidic dies and the circuit board; wires bridging the gaps between output sides of the fluidic dies and a front of the circuit board, wherein input sides of the fluidic dies are aligned with a back of the circuit board; a monolithic overmolding in the gaps and sealing the wires; and a fluid supply attached to the input side of a fluidic die of the fluidic dies.

12. The fluid ejection device of claim 11 , wherein the monolithic overmolding covers the front of the circuit board and not the back of the circuit board.

13. A method, comprising: placing a circuit board on a surface; placing a fluidic die on the surface adjacent to the circuit board, wherein the fluidic die is distanced from the circuit board, and wherein an input side of the fluidic die is aligned with a back of the circuit board; connecting an electrical interconnect between an output side of the fluidic die and the circuit board; and overmolding the electrical interconnect and a face of the circuit board.

14. The method of claim 13, wherein the surface is a sacrificial substrate, and wherein the method further comprises removing the sacrificial substrate from the circuit board and the fluidic die.

15. The method of claim 14, further comprising removing a fluid ejection assembly from an overmolded sheet, wherein the fluid ejection assembly comprises the fluidic die, the circuit board, the electrical interconnect, and an overmolded shape.