BACKGROUND

[0001] Printing devices are used to print images onto print media. Printing devices can use a variety of different technologies to print the images. For example, some print devices can print by jetting printing fluids (e.g., inkjet), some print devices can print using binding agents on a bed of build powder (e.g., additive printing), and some print devices can print by using electrophotography (e.g., laser printing), by way of non-limiting example.

[0002] The print devices can include a variety of different components from various modules (e.g., feeder trays, print paths, finishing modules, and the like) to smaller components (e.g., printheads). Various technologies can be used to assemble the printheads to print the images onto the print media. The printheads may be capped or taped during shipping, such as to keep the printheads from drying out or leaking.

BRIEF DESCRIPTION OF THE DRAWINGS [0003] FIG. 1 is a top view of an example printhead with adhesion features of the present disclosure;

[0004] FIG. 2 is a cross-sectional view of an example of a print nozzle of the printhead with adhesion features of the present disclosure;

[0005] FIG. 3 is a cross-sectional view of an example adhesion feature of the printhead with adhesion features of the present disclosure;

[0006] FIG. 4 is a cross-sectional view of an example print nozzle and adhesion features of the printhead with adhesion features of the present disclosure; [0007] FIG. 5 is a side cross-sectional view of an example of the printhead with adhesion features of the present disclosure;

[0008] FIG. 6 is a block diagram of example shapes of the adhesion features of the present disclosure.

DETAILED DESCRIPTION

[0009] Examples described herein provide printheads with adhesion features. As discussed above, printers can use various types of printing technologies. One type of technology is an inkjet printer.

[0010] The inkjet printer can use a printhead that stores inks. The ink can be dispensed and controlled electronically through electrodes of the printhead in communication with a controller of the printing device. One type of inkjet is a thermal inkjet (TIJ) printhead that uses a thermal resistor to locally heat a printing fluid to eject a drop of the printing fluid onto the print media.

[0011] The TIJ printhead can include a row of openings for each color that is dispensed by the TIJ printhead. During shipping the rows of openings can be covered with tape (e.g., a pressure sensitive adhesive (PSA) tape, a hot melt tape attached under temperature and applied pressure, and the like). The tape may attempt to cover the holes so that ink does not leak out of the TIJ printhead and may also prevent the different colors of ink from mixing with each other during shipping or storage.

[0012] However, the tape may not have good adhesion with ink in the openings. As a result, portions of the tape may lose adhesion and ink may leak out. In addition, where the tape does adhere to the openings when the tape is removed, the shear force from removal of the tape may damage the openings or nozzles. In addition, the top hat material of the TIJ printhead may be suspended over the chamber or slot area (e.g., unsupported from below) and may be susceptible to damage when the tape is removed.

[0013] The present disclosure provides adhesion features that can improve the adhesion of the tape to the top surface of the TIJ printhead. As a result, the ink is less likely to leak or mix with the other colors of ink. In addition, the tape may adhere better to the adhesion features. As a result, when the tape is removed, the adhesion features may absorb most of the shear force rather than the wet nozzles that dispense the ink. As a result, the adhesion features may prevent damage to the top hat layer and the wet nozzles of the TIJ printhead. [0014] FIG. 1 illustrates an example printhead 100 of the present disclosure.

It should be noted that FIG. 1 has been simplified for ease of explanation. The printhead 100 may include other components that are not shown. For example, the printhead 100 may include electronics to communicate with a controller to control ejection of printing fluid out of the printhead 100, may include a larger cartridge or body that is coupled to the printhead 100, and the like.

[0015] In an example, the printhead 100 may include a first array 102 of a plurality of print nozzles 108i-108 _n (hereinafter also referred to individually as a print nozzle 108 or collectively as print nozzles 108), a second array 104 of a plurality of print nozzles 110i — 110 _n (hereinafter also referred to individually as a print nozzle 110 or collectively as print nozzles 110), and a third array 106 of a plurality of print nozzlesl 12i — 112 _n (hereinafter also referred to individually as a print nozzle 112 or collectively as print nozzles 112). Although three arrays 102, 104, and 106 of print nozzles 108, 110, and 112, respectively, are illustrated in FIG. 1 , it should be noted that any number of array of print nozzles may be deployed.

[0016] In an example, each array 102, 104, and 106 may each be associated with a different color. In some examples, multiple arrays 102, 104, and 106 may be associated with each color (e.g., two or more arrays 102 of the print nozzles 108 for a first color, two or more arrays 104 of the print nozzles for a second color, and so forth). For example, print nozzles 108 of the array 102 may dispense a cyan color print fluid, the print nozzles 110 of the array 104 may dispense a yellow color print fluid, and the print nozzles 112 of the array 106 may dispense magenta color print fluid. In other words, a volume below the print nozzles 108, 110, and 112 may store print fluid. Thus, the print nozzles 108, 110, and 112 may also be referred to as “wet nozzles”.

[0017] In an example, the print nozzles 108, 110, and 112 may be formed on a top layer 152 of a body 150 of the printhead 100. Cross-sectional views that illustrate the volume below the print nozzles 108, 110, 112 and the various layers that form the body 150 are illustrated in the subsequent figures and discussed in further details below.

[0018] In an example, adhesion features 114 may be formed around the print nozzles 108, 110, and 112. The adhesion features 114 may be deployed in various shapes and patterns that mimic the print nozzles 108, 110, and 112.

The adhesion features 114 may not include print fluid and may also be referred to as “dry nozzles”.

[0019] In an example, the adhesion features 114 may be shared between the arrays 102, 104, and 106 of the print nozzles 108, 110, and 112, respectively. In other words, a single array or line of the adhesion features 114 may be formed between the array 102 and 104 or between the array 104 and 106, as shown in FIG. 1.

[0020] In an example, each array 102, 104, and 106 of print nozzles 108,

110, and 112, respectively, may include a separate set of adhesion features 114. In other words, adhesion features 114 may be formed around the array 102 of print nozzles 108, another set of adhesion features 114 may be formed around the array 104 of print nozzles 110, and so forth. Said another way, arrays 102, 104, and 106 may not share a line of adhesion features.

[0021] As noted above, the printhead 100 may be shipped with an adhesive layer applied to the top layer 152 over the print nozzles 108, 110, and 112. The adhesive layer may prevent the print fluid contained below the print nozzles 108, 110, and 112 from leaking or mixing during shipping and/or storage.

[0022] In an example, the design of the adhesion features 114 may cause the adhesion features 114 to absorb more of the linear peel force or sheer force compared to the print nozzles 108, 110, and 112 when the adhesive layer is removed. As a result, damage to the print nozzles 108, 110, and 112 and top hat layer (illustrated in FIG. 2 and described below) may be minimized or avoided when the adhesive layer is removed. In addition, the better adhesion of the adhesive layer to the adhesion features 114 may prevent color mixing between different colored print nozzles 108, 110, and 112.

[0023] FIG. 2 illustrates a cross-sectional view of an example print nozzle 112 (and similarly print nozzles 108 and 110) and FIG. 3 illustrates a cross- sectional view of an example adhesion feature 114. FIGs. 2 and 3 illustrate how an adhesive layer 214 interacts differently with the print nozzle 112 versus the adhesion feature 114.

[0024] Referring to FIG. 2, in an example, the print nozzle 112 may be formed on a substrate 202. The substrate 202 may be silicon or a complementary metal oxide semiconductor (CMOS) substrate.

[0025] A thermal inkjet (Tl J) resistor 218 may be fabricated on the substrate 202. The Tl J resistor 218 may include a controllable circuit that includes a resistor heater. When the circuit is activated, current may flow through the resistor heater to generate heat. The heat may locally heat a print fluid 216 contained in a chamber 230 of the print nozzle 112 to generate vapor bubbles. As the vapor bubbles burst, the force from the vapor bubbles may eject a drop of the print fluid 216 through an opening 210 of the print nozzle 112.

[0026] In an example, a primer layer 204 may be deposited on the substrate 202. The primer layer 204 may help adhesion of subsequent layers of photo definable polymers or negative photoresist material that are deposited to form the printhead 100 and the print nozzle 112. In an example, the photo definable polymers may include SU8.

[0027] In an example, layer 206 of the photo definable material may be deposited to form the chamber 230. A layer 208 of the photo definable material may be deposited on the layer 206 to form a top hat layer. The opening 210 may be formed in the layer 208 to form the print nozzle 112. The layers 206 and 208 and the opening 210 may be formed using photolithography techniques (e.g., deposition, expose, bake, and etch processes).

[0028] In an example, an adhesive layer 214 may be applied over the layer 208. The adhesive layer 214 may be a pressure sensitive adhesive (PSA) or a hot melt tape. For example, the adhesive layer 214 may include an adhesive that is melted under heat or pressure and then cooled.

[0029] In an example, a counterbore 212 may be etched into the layer 208 around the opening 210. The counterbore 212 may include a slanted or angled surface around the opening 210 to help the adhesive layer 214 to flow towards the opening 210 when melted during application. [0030] As shown in FIG. 2, when the adhesive layer 214 interacts with the opening 210, a convex bubble 220 is formed. The print fluid 216 helps to prevent adherence of the adhesive layer 214 to the sidewalls 232 of the opening 210. For example, the print fluid 216 may wet the sidewalls 232 to prevent adherence of the adhesive layer 214 to the sidewalls 232, which may cause the convex bubble 220 to be formed. As illustrated in FIG. 2, the convex bubble 220 may have a dome shape where an apex of the bubble is pointed towards the chamber 230. In addition, a minimal amount of the adhesive layer 214 interacts with sidewalls 232 of the opening 210.

[0031] FIG. 3 illustrates an example of how the adhesive layer 214 interacts with an opening 310 of the adhesion feature 114. FIG. 3 illustrates an example where the adhesive layer 214 includes an opening through the layer 206 of the photo definable material that forms a chamber 330. In other words, the adhesion feature 114 illustrated in FIG. 3 can be formed through the chamber layer of the body 150. In other examples, as illustrated in FIG. 4 and discussed below, the adhesion feature 114 may be formed through the top hat layer (e.g., the layer 208) without going through the chamber layer (e.g. , the layer 206). [0032] The adhesion feature 114 may be formed on the substrate 202 in a manner similar to the print nozzle 112 illustrated in FIG. 2. In addition, the adhesion feature 114 may be formed with the primer layer 204, the layer 206 of photo definable material, and the layer 208 of the photo definable material. However, the adhesion feature 114 may not include the TIJ resistor 218 and may be dry in the chamber 330. In other words, no print fluid 216 may be stored in the chamber 330 of the adhesion feature 114.

[0033] In an example, the opening 310 of the adhesion feature 114 may be formed through the layer 208. The adhesion feature 114 may also include the counterbore 212. In an example, a counterbore 212 may be etched into the layer 208 around the opening 310. The counterbore 212 may include a slanted or angled surface around the opening 310 to help the adhesive layer 214 to flow towards the opening 310 when melted during application.

[0034] As illustrated in FIG. 3, the adhesive layer 214 may interact differently with the opening 310 of the adhesion feature 114 compared to the opening 210 of the print nozzle 112. For example, since the adhesion feature 114 is dry (e.g., does not contain the print fluid 216), the adhesive layer 214 may form a concave bubble 322 as the adhesive layer 214 cools after application. The concave bubble 322 may have an inverted dome shape where an apex of the bubble is pointed away from the chamber 330 or towards the adhesive layer 214.

[0035] In addition, the adhesive layer 214 interacts with sidewalls 332 of the opening 310. In other words, the adhesive layer 214 may adhere to the sidewalls 332. As a result, a greater liner peel force may be applied to the adhesion features 114 compared to that of the print nozzle 112. In an example, the linear peel force of the adhesive layer 214 on the opening 310 can be approximately two times higher than the linear peel force of the adhesive layer 214 on the opening 210. When applied to an array of print nozzles 112 and adhesion features 114, the difference in linear peel force may be 10-50 times greater for the adhesion features 114.

[0036] As a result, when the adhesive layer 214 is removed when the printhead 100 is ready for use, the adhesion features 114 may absorb most of the linear peel force. The adhesion features 114 may be deformed from removal of the adhesive layer 214 and/or portions of the adhesive layer 214 inside of the opening 310 of the adhesion features 114, but the openings 210 of the print nozzles 108, 110, and 112 may remain intact or undisturbed. Thus, the printhead 100 may dispense the print fluid 216 properly during operation.

[0037] In an example, to maximize the linear peel force absorbed by the opening 310, the opening 310 may have a high aspect ratio. For example, the aspect ratio of the opening may be greater than one. The aspect ratio may be defined as a ratio of a height 324 of the opening 310 to a width 326 of the opening 310. In an example, a diameter or width 326 of the opening 310 may be approximately 10-20 microns. Thus, the height 324 (or opening depth) of the opening 310 may be approximately 5-40 microns.

[0038] FIG. 4 illustrates another example of a cross-sectional view of the printhead 100 along line A-A shown in FIG. 1 . It should be noted that FIG. 4 is not necessarily drawn to scale. For example, the distance between the print nozzle 112, the adhesion feature 114, and the print nozzle 110 shown in FIG. 4 may not necessarily be drawn to scale compared to the distance between the print nozzle 112, the adhesion feature 114, and the print nozzle 110 shown in FIG. 1.

[0039] FIG. 4 illustrates how the adhesion feature 114 may be located between print nozzles 112 and 110 of different colored print fluids or inks. In an example, the adhesion feature 114 may be formed through the layer 208 of the photo definable material (e.g., the top hat layer) and stop at the layer 206.

Unlike the example adhesion feature 114 illustrated in FIG. 3, the example adhesion feature 114 in FIG. 4 may have a solid layer 206. This may save some processing time and costs when forming the adhesion feature 114 in FIG. 4 compared to the forming the adhesion feature 114 through the layer 206 as shown in FIG. 3.

[0040] The adhesion feature 114 may include an opening 310 formed through the layer 208. In an example, the sidewalls 332 of the opening 310 may be angled, tapered, or slanted to form a counterbore. The angle of the counterbore (e.g., an angle formed between two opposite sidewalls 332 of the tapered opening 310 as shown by a line 350) may be approximately 90 degrees to 170 degrees. The counterbore may help produce additional sheer force in the adhesive layer 214, stimulating deeper penetration of the adhesive layer 214 into the opening 310. This deeper penetration may help to anchor the adhesive layer 214 into the opening 310. In other words, the cross-section of the opening 310 may have a trapezoidal shape. For example, the concave bubble 322 may be formed in the adhesive layer 214 with portions that adhere to the sidewalls 332. The angle of the sidewalls 332 may help form an anchor shape inside of the opening 310. Anchoring the adhesive layer 214 may create more liner peel force, further helping the adhesion feature 114 to absorb the liner peel force when the adhesive layer 214 is removed.

[0041] In an example, the print nozzles 110 and 112 may include similar features as the print nozzle 112 illustrated in FIG. 2. For example, the print nozzles 110 and 112 may be formed on a substrate 202. A TIJ resistor 218 may be formed on the substrate 202 in the print nozzle 110 and the print nozzle 112.

[0042] A primer layer 204 may be applied on the substrate 202. Subsequent layers of photo definable material may be deposited and etched to form the layers 206 and 208. An opening 210 may be formed through the layer 208.

The opening 210 may also have angled or slanted sidewalls 232. In other words, the cross-section of the opening 210 may have a trapezoidal shape.

Print fluid 216i may be contained in the chamber 230i of the print nozzle 112. Print fluid 216 ₂ may be contained in the chamber 230 ₂ of the print nozzle 110. [0043] As described above, the adhesive layer 214 may form a convex bubble 220 in the openings 210 of the print nozzle 110 and 112. The print fluid 216 ₁ and 216 ₂ may cause the adhesive to cool and form the convex bubble 220 where a minimal amount of the adhesive layer 214 contacts the sidewalls 232 of the openings 210 of the print nozzles 110 and 112.

[0044] Thus, the adhesion features 114 may reduce damage to the print nozzles 110 and 112 when the adhesive layer 214 is removed. The adhesion features 114 may also decrease a probability of ink under tape failure, decrease a latent ink under tape (IUT) rate, and prevent ink color mixing. Furthermore, the adhesion features 114 may allow a low surface energy (LSE) photo definable polymer to be used in the layer 208. In other words, a low surface energy top hat can be used for the printhead 100 with the adhesion features 114.

[0045] FIG. 5 illustrates a side-cross-sectional view of the example printhead 100 with adhesion features of the present disclosure. The cross-sectional view of FIG. 5 is taken along a length of the adhesion feature 114 shown in the top view illustrated in FIG. 1.

[0046] In an example, the printhead 100 may include a plurality of adhesion features 114i to 114 _m . The adhesion features 114 may be formed in the body 150 of the printhead 100. An adhesive layer 214 may be applied over the adhesion features 114 and the top surface 152 of the printhead 100. As discussed above, the design of the adhesion features 114 may absorb most of the linear peel force when the adhesive layer 214 is removed. As a result, the print nozzles 108, 110, and 112 may be protected from deformation or tearing when the adhesive layer 214 is removed.

[0047] In an example, the adhesion features 114 may be discrete adhesion features or may be a continuous feature. For example, the adhesion feature 114 may have a discrete shape (e.g., non-continuous) that is periodically spaced apart around the print nozzles 108, 110, and 112. In another example, the adhesion features 114 may be a continuous shape or line that is formed around the print nozzles 108, 110, and 112.

[0048] FIG. 6 illustrates example shapes of the adhesion features 114. Each shape illustrated in FIG 6 may have a width or diameter of approximately 10-20 microns. The height or depth of each shape may be approximately 5-40 microns to achieve a high aspect ratio of greater than 1 , as described above. In addition, each shape illustrated in FIG. 6 illustrates a top view of a possible shape of the adhesion features 114. The adhesion features 114 may be angled, tapered, or slanted to increase sheer force during tape application and to provide deeper penetration of the tape material into the adhesion features 114.

[0049] In an example, the adhesion feature 114 may include a continuous line 602. The continuous line 602 may be a meandering line that has a geometric shape. For example, the continuous line 602 may form a periodic pattern of squares or rectangles. In an example, the adhesion feature 114 may be a zig zag line 604. For example, the zig zag line 604 may include angled lines and parallel lines.

[0050] In an example, the adhesion feature 114 may be formed by discrete circular openings 606. For example, a line of separate circular openings 606 may form the adhesion feature 114.

[0051] In an example, the adhesion feature 114 may be formed by multiple arrays of discrete circular openings 608. For example, two or more lines of circular openings 608 may form the adhesion feature 114. In an example, the lines of circular openings 608 may be staggered.

[0052] In an example, the adhesion feature 114 may be formed by other discrete shapes. For example, the adhesion feature 114 may include a chevron shape 610. In an example, the adhesion feature 114 may include a line array 612.

[0053] The variety of shapes 602, 604, 606, 608, 610, and 612 illustrated in FIG. 6 may vary the adhesive layer 214 to adhesion feature 114 interfacial area. In other words, the shape of the adhesion feature 114 may be varied to control an amount of linear peel force for a particular printhead 100.

[0054] It should be noted that a few examples of possible shapes of the adhesion feature 114 are illustrated in FIG. 6. Other shapes and patterns may be within the scope of the present disclosure as long as shape has a high aspect ratio. In addition, the adhesion feature 114 may be deployed in a single shape or may include a variety or mix of different shapes. For example, adhesion features 114 in a first shape may be used around print nozzles 108 and adhesion features 114 in a second different shape may be used around the print nozzles 110 and/or 112.

[0055] It will be appreciated that variants of the above-disclosed and other features and functions, or alternatives thereof, may be combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, or variations therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.