WO2021183134A1

WO2021183134A1 - Device with fluid directing trenches

Info

Publication number: WO2021183134A1
Application number: PCT/US2020/022565
Authority: WO
Inventors: Jose Luis Ramos; Daniel W. Petersen; Cary G. Addington
Original assignee: Hewlett-Packard Development Company, L.P.
Priority date: 2020-03-13
Filing date: 2020-03-13
Publication date: 2021-09-16

Abstract

An example fluid ejection device includes a package comprising a molded compound surrounding a fluidic die and a fluid directing trench formed within the molded compound to control fluid flow on a surface of the molded compound and the fluidic die.

Description

DEVICE WITH FLUID DIRECTING TRENCHES

Background

[0001] Fluid devices, such as for manipulation and testing of fluids, may use a combination of electronics and fluidic channels. In one implementation of fluid devices, for example, fluid ejection systems may operate by ejecting a fluid from nozzles to form images on media and/or to form three-dimensional objects, for example. In some implementations, a fluidic die may be used to expel fluid and may be connected to a larger fluid ejection device comprising a molded structure. A fluidic die, as well as electrical components of the larger fluid ejection device, may be protected, for instance from electrical shorts, using an encapsulation material in some implementations.

Brief Description of the Drawings

[0002] Figure 1 is a diagram of an example fluid ejection device according to the present disclosure.

[0003] Figure 2 is a top view of a portion of an example fluid ejection device including a fluidic die and a fluid directing trench according the to present disclosure.

[0004] Figure 3 is another top view of a portion of an example fluid ejection device including a plurality of fluidic dies and fluid directing trenches according to the present disclosure.

[0005] Figure 4 is a cross-sectional view of a portion of an example fluid ejection device including a plurality of fluid directing trenches.

[0006] Figure 5 is yet another top view of a portion of an example fluid ejection device including a plurality of fluidic dies, a plurality of fluid directing trenches, and a set of encapsulation beads according to the present disclosure.

Detailed Description

[0007] Returning to the example of a fluid ejection device, noted above, fluid may travel through fluid feed holes towards ejection chambers containing fluid actuators (e.g., thermal resistors, piezo elements, etc.). Actuation of the fluid actuators can cause fluid droplets to be ejected, via nozzles, and onto media (e.g., a print medium). In some examples, nozzles may be formed as an opening in a thin film layer applied over a fluidic die in which a fluid feed hole is formed. The thin film layer may also form the ejection chambers. In other examples, the nozzles may be formed in the fluidic die, and a substrate connected to the fluidic die may contain the fluid feed holes (e.g., an inverted inkjet fluidic die).

[0008] As noted above, the fluidic die includes electronic components (e.g., wire traces, bond pads, etc.), such as to provide an electrical connection to other components of the fluid ejection device. An encapsulation material (e.g., and adhesive material) may be used to avoid fluidic contact with the electronic components, such as might cause electrical shorts. The encapsulation material can be applied to a desired portion of the fluidic die, such as exposed electrical traces on a top side of the fluidic die, as a bead of encapsulation materials or set of beads in a state in which the encapsulation material initially flows. These beads of encapsulation materials are referred to herein as “encapsulation beads”.

[0009] The encapsulation beads can experience spillover in which the encapsulation material spills over the desired locations for encapsulation, flows too quickly when dispensed, and/or and spreads onto parts of a package of the fluid ejection device, resulting in inconsistent coverage of the encapsulation material. This can cause electrical shorts if the coverage is inadequate in particular areas of the package (e.g., electrical shorts caused by fluids contacting exposed electronic components), cause encapsulation material flow to be outside of specifications of the fluid ejection device, or it can cause failure of components not meant to interact with the encapsulation material such as a wiper or a pen/pen body of the fluid ejection device.

[0010] In some implementations, fluid ejection devices include blocks of fluidic dies with large surface areas including trenches in a photoresist layer of the fluid dies. Due, in part, to the surface area of the fluidic dies, these trenches can capture excess encapsulation material to reduce spillover. Other implementations, however, include fluidic dies without large surface areas with trenches large enough to accommodate significant excess encapsulation material. For instance, in examples in which fluidic ejection devices include fluidic die slivers (e.g., fluidic dies that are significantly narrower than the width of the die) within a molded compound, trenches (if any) in the fluidic dies may not be effective at slowing a flow of encapsulation material, rerouting encapsulation material (e.g., “wi eking away” from a protected component), or capturing excess encapsulation material, which may result in damage to the fluidic die or other components of an associated package and/or fluid ejection device.

[0011] In contrast, examples of the present disclosure include fluid directing trenches formed within a molded compound of a package of a fluid ejection device and between fluidic dies of the package. The molded compound can include an epoxy molded compound (EMC), a liquid crystal polymer (LCP), a polyethylene naphthalate (PEN), a polyethylene terephthalate (PET), a polyphenylene sulfide (PPS), a polyamide, a photoresist, a polymer, a multi- layered lead-frame, a plastic, or a metal, among others. The fluid directing trenches can control a flow an encapsulation material in a fluidic forme on a surface of the molded compound and a fluidic die surrounded by the molded compound. For instance, encapsulation material spillover can be controlled and contained using the fluid directing trenches, protecting the surface of the molded compound and the fluidic dies from an inconsistent or excess amount of encapsulating material. The fluid directing trenches direct an encapsulation material in a fluidic form that is different than the fluid ejected from a fluid ejection device (e.g., encapsulation material vs. printing fluid).

[0012] The figures herein follow a numbering convention in which the first digit or digits correspond to the drawing figure number and the remaining digits identify an element or component in the drawing. Similar elements or components between different figures may be identified by the use of similar digits. For example, 108 may reference element “08” in Figure 1, and a similar element may be referenced as 208 in Figure 2. Multiple analogous elements within one figure may be referenced with a reference numeral followed by a hyphen and another numeral or a letter. For example, 108-1 may reference element 08-1 in Figure 1 and 108-2 may reference element 08-2, which can be analogous to element 08-1. Such analogous elements may be generally referenced without the hyphen and extra numeral or letter. For example, elements 108-1 and 108-2 may be generally referenced as 108.

[0013] Elements shown in the various figures herein can be added, exchanged, and/or eliminated so as to provide a number of additional examples of the present disclosure. In addition, the proportion and the relative scale of the elements provided in the figures are intended to illustrate the examples of the present disclosure and should not be taken in a limiting sense. As used herein, the designator “m”, “n”, and “p” particularly with respect to reference numerals in the drawings, indicates that a number of the particular feature so designated can be included with examples of the present disclosure. The designators can represent the same or different numbers of the particular features.

[0014] Figure 1 is a diagram of an example fluid ejection device 100 according to the present disclosure. The fluid ejection device 100 can include a pen body 120 (e.g., an inkjet pen body) and a package 106 comprising a molded compound 110 surrounding a plurality of fluidic dies (e.g., silicon fluidic dies) 108-1, 108-2. 108-n. Adjacent to the package 106 can be a set of encapsulation beads 104-1, 104-2. An encapsulation material in a fluid form (e.g., a fluidic state) can be used to form the set of encapsulation beads 104 onto the package 106. The set of encapsulation beads 104 may act to protect components of the fluid ejection device (e.g., flexible circuits, such as the flexible circuit 102).

[0015] The fluid ejection device 100 also includes a fluid directing trench 112 to control fluid flow on a surface of the molded compound 110 (e.g. the top surface visible in Figure 1) and on the fluidic dies 108. Controlling fluid flow can include, in some examples, keeping the encapsulation material in a fluid form on the surface of the molded compound 110 at a desired level (e.g., within a specification of the fluid ejection device 100). For instance, when the set of encapsulation beads 104 are applied to package 106 as fluid, the encapsulation material in the fluid form may spill over the boundaries of one or both of the desired locations of the encapsulation beads 104-1 , 104-2. Without the fluid directing trench 112, encapsulation material in a fluid form may spill into undesired locations of the package 106 or other areas of the fluid ejection device 100.

[0016] The fluid directing trench 112 can capture the excess encapsulation material in a fluid form and keep it from causing damage to components of the fluid ejection device 100 or interruptions to a fluid ejection process or direct excess encapsulation material in a fluid form away from the package 106. For instance, the fluid directing trench can direct encapsulation material in a fluid form away from an undesired location on the package responsive to a level of the encapsulation material in a fluid form reaching a threshold level on the molded compound 110. The threshold level, for instance, can include a level set by specifications of the fluid ejection device 100 and/or a level determined to cause damage to components of the fluid ejection device 100. While one fluid directing trench 112 is illustrated in Figure 1, more than one fluid directing trench 112 may be formed in the molded compound 110. Forming of the fluid directing trench 112 can include etching, laser engraving, molding, using a vibration stylus, or using a micromilling machine, among other engraving and/or etching approaches to form the fluid directing trench 112 into the molded compound 110. The fluid directing trench 112 is formed in the molded compound 110.

[0017] A size and shape of the fluid directing trench 112, as well as the number of fluid directing trenches 112 formed in the molded compound 110 can be dependent on a strength of the package 106. For instance, a stronger package 106 and associated molded compound 110 (e.g., deeper, wider, denser, etc.) can support a deeper and/or wider fluid directing trench 112. Similar, a stronger package 106 and associated molded compound 110 (e.g., deeper, wider, denser, etc.), may support more numerous fluid directing trenches 112, as compared to a weaker package 106 and associated molded compound 110 (e.g., thinner, narrower, less dense, etc.). [0018] In some examples, the shape and size of the fluid directing trench 112 and/or the number of trenches 112 formed in the molded compound 110 can be dependent on a viscosity of the encapsulation material in a fluid form released from the set of encapsulation beads 104. For instance, a thinner encapsulation material in a fluid form may flow faster than a thicker encapsulation material in a fluid form resulting in faster spillover as compared to a slower spillover of the thicker encapsulation material in a fluid form. In such an example, the fluid directing trench 112 may be deeper, wider, and/or there may be a plurality of fluid directing trenches 112 to control fluid flow on a surface of the molded compound 110 and the fluidic dies 108. In contrast, the fluid directing trench 112 may be shallower, thinner, and/or there may a single fluid directing trench 112 to control fluid flow on a surface of the molded compound 110 and the fluidic dies 108. A material of the molded compound may also be considered when determining a fluid directing trench 112 size, shape, etc. For instance, different materials may allow for faster or slower fluid flow. In some examples, the fluid directing trench 112 can serve as a reservoir for excess encapsulation material in a fluid form or encapsulation material in a fluid form in the fluid directing trench can be moved elsewhere in the fluid ejection device.

[0019] Figure 2 is a top view of a portion of an example fluid ejection device including a fluidic die 208 and a fluid directing trench 212 according the to present disclosure. A package 206 can include a molded compound 210 (e.g., an EMC) surrounding a fluidic die 208 and having a fluid directing trench 212 formed therein. The package 206, in some examples, can include a precision over mold (POM) package, which can include a package having silicon slivers over-molded in an EMC (e.g., molded compound 210).

[0020] An encapsulation bead and/or a set of encapsulation beads (not illustrated here) in a fluid form can be formed to protect components of the package 206 and components of the fluid ejection device. When doing so, the flow of the encapsulation material in a fluid form can be controlled using the fluid directing trench 212, to control an encapsulation material in a fluid form level on a surface of the molded compound 210 (e.g., the surface visible in Figure 2), and the fluidic die 208. For instance, after the encapsulation material in a fluid form is placed on package 206, excess encapsulation material in a fluid form can flow into the fluid directing trench 212 via an on-die fluid directing trench 214 present on the fluidic die 208. While one fluid directing trench 212 and one fluidic die 208 are illustrated here, more fluid directing trenches 212 and/or fluidic dies 208 may be present in the package 206.

[0021] Figure 3 is another top view of a portion of an example fluid ejection device including a plurality of fluidic dies 308-1, 308-2. 308-n and fluid directing trenches 312-1. 312-2 according to the present disclosure.

Figure 3 includes a package 306 including a molded compound 310 surrounding a plurality of fluidic dies 308 (e.g., silicon fluidic dies) positioned substantially parallel to one another. The molded compound 310 can include a first fluid directing trench 312-1 and a second fluid directing trench 312-2 located between and substantially orthogonal to each one of the plurality of silicon fluidic dies 308 and formed within the molded compound 310. Substantially orthogonal can comprise, for example, a little more than orthogonal or a little less than orthogonal, but within a threshold. For example, a substantially orthogonal direction can comprise a direction that is closer to orthogonal than parallel. Similarly, substantially parallel can comprise a little more than parallel or a little less than parallel, but within a threshold. For example, a substantially parallel direction can comprise a direction that is closer to parallel than orthogonal.

[0022] The first and the second fluid directing trenches 312 can capture encapsulation material in a fluid form and control fluid flow on a surface of the molded compound 310 (e.g., the visible surface in Figure 3) and the plurality of fluidic dies 308. For instance, encapsulation material in a fluid form can be us to protect components (e.g., flexible circuits, electrical traces, etc.) of the package 306 and components of the fluid ejection device. When doing so, the flow of the encapsulation material in a fluid form can be controlled using the fluid directing trenches 312 to control a fluid level on a surface of the molded compound 310 (e.g., the surface visible in Figure 2), and the fluidic dies 308.

For instance, the encapsulation material in a fluid form can be placed on package 306 and excess can flow into the fluid directing trenches 312. For instance, excess encapsulation material in a fluid form on the fluidic die 308-1 can flow into fluid directing trenches 312, via on-die fluid directing trenches 314- 1 and 314-n+1 present on the fluidic dies 308. Excess encapsulation material in a fluid form on the fluidic die 308-2 can flow into fluid directing trenches 312 via on-die fluid directing trenches 314-2 and 314-n+2 present on the fluidic die 308- 2, and excess encapsulation material in a fluid form on the fluidic die 308-n can flow into fluid directing trenches 312 via the on-die fluid directing trenches 314-n and 314-2n present on the fluidic die 308-n. The first fluid directing trench 312- 1 and/or the second fluid directing trench 312-2 may direct the encapsulation material in a fluid form elsewhere on the fluid ejection device or may act as a reservoir for excess fluid, in some examples.

[0023] While two fluid directing trenches 312 and three fluidic dies are illustrated in Figure 3, more or fewer fluid directing trenches 312 and/or fluidic dies 308 may be present. For instance, additional trenches may be formed in positions substantially parallel to the first fluid directing trench 312-1 and the second fluid directing trench 312-2 and additional fluidic dies may be positioned substantially parallel to the plurality of fluidic dies 308. The fluid directing trenches 312 may be located in positions different than those shown in Figure 3, may be different sizes (e.g., smaller, bigger, wider, deeper, shallower, longer, shorter, etc.) than those shown in Figure 3, and/or may be different shapes (e.g., rectangle, trapezoid, sinusoidal, etc.) than those shown in Figure 3. In some examples, sidewalls of the fluid directing trenches 312 may be different shapes including, for instance, straight, angled, or stepped, among others. The shape and sizes of the fluid directing trenches 312 may not be uniform, in some instances. Similar principles with respect to fluid flow as previously described are applicable when more or fewer fluid directing trenches 312 and/or fluidic dies 308 are present and/or when different shapes, sizes, positions, etc. of fluid directing trenches 312 are present.

[0024] Figure 4 is a cross-sectional view of a portion of an example fluid ejection device including a plurality of fluid directing trenches 412-1 and 412-2, as viewed from cross-sectional line A in FIG. 3. For instance, the fluid directing trenches 412-1 and 412-2 can be analogous to the fluid directing trenches 312- 1 and 312-2. Figure 4 illustrates a package 406 (e.g., a POM package) including a molded compound 410 (e.g., an EMC) having the plurality of fluid directing trenches 412 formed therein. For instance, the fluid directing trenches 412 can be formed in the molded compound 410 by etching the molded compound 410, molding the fluid directing trenches 412, or engraving the molded compound 410 using a vibration stylus, micromilling machine, laser, etc., or saw, among others. Fluid flow on the molded compound 410 and/or on the fluidic dies from a set of encapsulation beads can be controlled by capturing the encapsulation material in a fluid form in the fluid directing trenches 412 and/or directing it away from areas of the package 406 of fluid ejection device that may be damaged by excess encapsulation material in a fluid form.

[0025] Figure 4 illustrates that the fluid directing trenches 412 may be different depths. For instance, fluid directing trench 412-1 is shallower than fluid directing trench 412-2. While the depths are a differentiator here, the trenches may also be different widths and/or shapes, may have different sidewall angles, may not be uniform, and/or may have different trench-bottom shapes, among others.

[0026] Figure 5 is a yet another top view of a portion of an example fluid ejection device including a plurality of fluidic dies 508-1. 508-n, a plurality of fluid directing trenches 512-1. 512-p, and a set of encapsulation beads 504-

1 , 504-2 according to the present disclosure. The set of encapsulation beads 504 can be released as fluid (e.g., as an encapsulation material) to protect components of a package 506 of the fluid ejection device.

[0027] The package 506 can include a molded compound 510, the fluidic dies 508, the fluid directing trenches 512 formed in the molded compound 510, and on-die fluid directing trenches 518-1, 518-2, 518-3. 518-m formed on each one of the fluidic dies 508. In the example illustrated in Figure 5, the on- die fluid directing trenches 518 are located near each encapsulation bead of the set of encapsulation beads 504, however examples are not so limited. For instance, the one-die fluid directing trenches 518 may be located similarly to the on-die fluid directing trenches 214, 314 illustrated in Figures 2 and 3 or may be co-located on the fluidic dies 508 with other on-die fluid directing trenches. [0028] The fluid directing trenches 512 and the on-die fluid directing trenches 518 can control fluid flow from the set of encapsulation beads 504 on a surface of the molded compound 510 (e.g., the surface visible in Figure 5) and the fluidic dies 508. For instance, as encapsulation material in a fluid form begins to spill over the boundaries of the set of encapsulation beads 504, it can flow into the fluid directing trenches 518. As the encapsulation material in a fluid form spills over the fluid directing trenches 518, the encapsulation material in a fluid form can flow into the fluid directing trenches 512, reducing inconsistent or undesired amounts of encapsulation material in a fluid form. In some examples, as the encapsulation material in a fluid form is passing between encapsulation bead 504-1 and encapsulation bead 504-2, the encapsulation material in a fluid form may spill over the fluidic dies 508 and spill into the fluid directing trenches 512. The fluid directing trenches 512, in some instances, can serve as reservoirs for the encapsulation material in a fluid form and/or can direct the encapsulation material in a fluid form elsewhere in the fluid ejection device.

[0029] In the foregoing detailed description of the present disclosure, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration how examples of the disclosure may be practiced. These examples are described in sufficient detail to enable those of ordinary skill in the art to practice the examples of this disclosure, and it is to be understood that other examples may be utilized and that process, electrical, and/or structural changes may be made without departing from the scope of the present disclosure.

Claims

What is claimed:

1. A fluid ejection device, comprising: a package comprising a molded compound surrounding a fluidic die; and a fluid directing trench formed within the molded compound to control fluid flow on a surface of the molded compound and the fluidic die.

2. The device of claim 1 , wherein the package is a precision over mold (POM) package.

3. The device of claim 1 , wherein the package further includes an additional fluidic die.

4. The device of claim 3, wherein the fluid directing trench is located between the fluidic die and the additional fluidic die.

5. The device of claim 1 , further comprising the fluid directing trench to direct encapsulation material in a fluid form away from an undesired location on the package responsive to a level of the encapsulation material in a fluid form reaching a threshold level on the molded compound.

6. The device of claim 1 , wherein the first fluid directing trench is molded into the molded compound.

7. The device of claim 1 , wherein the fluid directing trench is etched into the molded compound.

8. A fluid ejection device, comprising: a package comprising a molded compound surrounding a first silicon fluidic die and a second silicon fluidic die; the molded compound comprising: a first fluid directing trench located between and substantially orthogonal to the first silicon fluidic die and the second silicon fluidic die and formed within the molded compound; and a second fluid directing trench located between and substantially orthogonal to the first silicon fluidic die and the second silicon fluidic die and formed within the molded compound, wherein the first and the second fluid directing trenches capture encapsulation material in a fluid form and control flow of the encapsulation material in a fluid form on a surface of the molded compound, the first silicon fluidic die, and the second silicon fluidic die.

9. The device of claim 8, further comprising a third fluid directing trench within the first silicon fluidic die and positioned in parallel with the first and the second fluid directing trenches.

10. The device of claim 8, wherein the first fluid directing trench and the second fluid directing trench are laser engraved into the molded compound.

11. The device of claim 8, wherein the encapsulation material in a fluid form comprises an adhesive encapsulation material.

12. The device of claim 8, wherein the molded compound is an epoxy molded compound (EMC).

13. A fluid ejection device, comprising: a precision over mold (POM) package, comprising: an epoxy molded compound (EMC); a plurality of silicon fluidic dies located on the EMC; a plurality of fluid directing trenches formed within the EMC to control flow of an encapsulation material in a fluid form on a surface of the EMC and the plurality of silicon fluidic dies; and an on-die fluid directing trench formed on each one of the plurality of silicon fluidic dies to control flow of encapsulation material in the fluid form on the surface of the EMC and the plurality of silicon fluidic dies.

14. The device of claim 13, wherein a first one of the fluid directing trenches and a second one of the plurality of fluid directing trenches formed within the EMC are different sizes.

15. The device of claim 13, further comprising a flexible circuit coupled to the package and protected by a set of encapsulation beads.