Patent Description:
The printing fluid may be ejected from a printhead. The printheads may be packaged and sealed to prevent the printing fluid from leaking during transport.

<CIT> describes a printhead die with a trench and a centrally located opening formed in a barrier layer made of a polymer material and covered by a metallic nozzle plate.

<CIT> discloses a printhead die with a firing chamber formed in a barrier layer having a thickness of about <NUM> covered by an orifice plate having a thickness of <NUM> to <NUM>.

<CIT> discloses a printhead die with a liquid chamber formed by a plate member having an inclination toward an ink-contacting surface.

The present invention refers to a printhead die according to claim <NUM>.

Examples described herein provide an integrated printhead with an improved unsupported top hat layer and chamber to prevent tearing of the top hat layer during a de-taping process. For example, printheads can be packaged and sealed after manufacturing to ensure that the printing fluid in the printhead does not leak or evaporate before use.

As printhead technology has advanced, the materials used in the manufacturing processes have also changed. In some examples, tape can be placed over the printhead to prevent the printing fluid from leaking. However, when the tape is removed, the removal of the tape may create deflection and stress on the portions of the printhead that can result in damage to the printhead. The resulting damage can cause the printing fluid to leak or escape.

Mechanical solutions can be created, but the mechanical solutions can be expensive to implement. Tape is a relatively low cost material that can help to reduce the overall costs of the printhead.

Examples herein provide a printhead that minimizes beam length (e.g., a width across an unsupported top hat portion) where taping begins to minimize an amount of deflection when the tape is removed. Minimizing the amount of deflection at the point of initiation of tape adhesive to the unsupported top hat layer may prevent the top hat layer from being damaged when the tape is removed. As a result, tape can still be used to seal the printing fluid in the printhead without damaging the top hat layer of the printhead during removal of the tape by the customer.

<FIG> illustrates a top view of an example printhead die <NUM> and <FIG> illustrates a cross-sectional view of the example printhead die <NUM> along a dashed line <NUM>. The reader may refer to <FIG> and <FIG> simultaneously to view the different layers of the printhead die <NUM> that are discussed in <FIG>, but may be difficult to see in the top view illustrated in <FIG>.

In one example, the printhead die <NUM> may be part of an integrated printhead (IPH). IPHs may be devices that combine an ink cartridge with a printhead. In other words, unlike some printers that have distinct printheads and printing fluid containers (e.g., off-axis ink supply with permanent printheads), the printhead may be integrated into the ink cartridge in an IPH.

In one example, the printhead die <NUM> may include a substrate <NUM> that includes slotted portions <NUM><NUM> - <NUM>n that form a fluidic connection to the printhead (hereinafter also referred to individually as a slotted portion <NUM> and collectively as slotted portions <NUM>). In an example, the substrate <NUM> may be a silicon substrate. The slotted portions <NUM> may each be associated with a different colored printing fluid.

Although multiple slotted portions <NUM> are illustrated in <FIG>, it should be noted that a single slotted portion may be included in a single printhead die <NUM>. In other words, printhead die <NUM> can be fabricated with multiple slotted portions <NUM> for multiple colors or can be fabricated with a single slotted portion <NUM> for a single color.

The number of slotted portions <NUM> created in the substrate <NUM> may be a function of a number of different colors of printing fluid that are dispensed by the printhead die <NUM>. For example for a printhead die <NUM> that dispenses cyan, yellow, and magenta colors, the printhead die <NUM> may have three slotted portions <NUM> (e.g., a cyan slot, a yellow slot, and a magenta slot on a single printhead substrate <NUM>).

In one example, the slotted portions <NUM> may include a top hat layer <NUM>, and a chamber layer <NUM> (illustrated in <FIG>) that is beneath the top hat layer <NUM> that is etched to form walls <NUM>. As shown in <FIG>, the top hat layer <NUM> may be arranged above the chamber layer <NUM> and also above the substrate <NUM>. Thus, as illustrated in <FIG>, the top hat layer <NUM> is to be understood as being arranged above both the substrate <NUM> and the chamber layer <NUM> (e.g., in the z-axis, coming out of the page). The walls <NUM> are illustrated as dashed lines that surround a perimeter of the slotted portions <NUM>. <FIG> illustrates how the walls <NUM> support the outer edges of the top hat layer <NUM>.

The portions of the chamber layer <NUM> that are etched away may form a void <NUM>. The void <NUM> is illustrated in diagonal lines in the top view illustrated in <FIG>. <FIG> illustrates the void <NUM> as a volume formed between the top hat layer <NUM>, the walls <NUM> of the chamber layer <NUM>, and the substrate <NUM>. The portions of the top hat layer <NUM> that are over the void <NUM> may be referred to as the unsupported top hat layer <NUM>. The portions of the top hat layer <NUM> that rest on the chamber layer <NUM> and/or the walls <NUM> may be referred to as the supported top hat layer portion.

In one example, the top hat layer <NUM> may include an initial unsupported top hat layer portion <NUM>. The initial unsupported top hat layer portion <NUM> may be defined by a first end <NUM> and a second end <NUM>. <FIG> illustrates a more detailed view of the initial unsupported top hat layer portion <NUM>, and is discussed in further details below.

As illustrated in <FIG>, the void <NUM> in the chamber layer <NUM> may form a volume to store printing fluid <NUM>. The void <NUM> may run along a length of the slotted portion <NUM> and may also be referred to as a fluid channel that runs along a length of the slotted portion <NUM>. The printing fluid <NUM> may be fed through an ink feed hole <NUM> (shown in dashed lines in <FIG>) formed through the substrate <NUM>, as shown in <FIG>.

The printing fluid <NUM> may then be ejected via printing fluid ejection chambers <NUM><NUM> to <NUM>m (of which only <NUM><NUM>, <NUM><NUM>, and <NUM>m are labeled, hereinafter also referred to individually as a printing fluid ejection chamber <NUM> or collectively as printing fluid ejection chambers <NUM>). The printing fluid ejection chambers <NUM> may be formed or coupled to opposite sides of the fluid channel and along a length of the chamber layer <NUM> and top hat layer <NUM>. Said another way, in <FIG>, if the top view of the slotted portion <NUM> were divided along a length of the slotted portion (e.g., left to right when viewing the page), the printing fluid ejection chambers <NUM> may be formed on opposite sides (e.g., along the perimeter on both sides of the slotted portion <NUM> when viewed from the top as shown in <FIG>). An opening <NUM><NUM> to <NUM>p (of which only <NUM><NUM>, <NUM><NUM>, <NUM><NUM>, and <NUM>p are labeled; hereinafter also referred to individually as an opening <NUM> or collectively as openings <NUM>) may be formed in the top hat layer <NUM> over each one of the printing fluid ejection chambers <NUM>.

The printing fluid ejection chambers <NUM> are shown formed as a portion of the cross-section of <FIG> shown by dashed lines. The volume created by the void <NUM> may store the printing fluid <NUM> that is fed through the ink feed hole <NUM>. The printing fluid <NUM> may be fed to each one of the printing fluid ejection chambers <NUM> during operation of the printhead die <NUM>. For example, the printing fluid <NUM> may flow through the fluid channel that runs into and out of the page in <FIG>.

<FIG> illustrates the openings <NUM> of the printing fluid ejection chambers <NUM>. The openings <NUM> may allow the printing fluid <NUM> to be ejected one drop at a time. The printing fluid may be ejected by an actuator <NUM> that forces the printing fluid through the openings <NUM> (e.g., a resistive element, a piezo actuator, etc.).

According to the invention, the top hat layer <NUM> and the chamber layer <NUM> are formed or fabricated from the same material. For example, the top hat layer <NUM> and the chamber layer <NUM> may be fabricated from a photo definable polymer or negative photoresist material. An example of the photo definable polymer may include SU8. The photo definable polymer may be soft or flexible.

The chamber layer <NUM> is formed by depositing the photo definable polymer onto the substrate <NUM>. A lithography and etching process may be applied to the photo definable polymer to form the void <NUM>. The top hat layer <NUM> may be a thin layer that is deposited on top of the chamber layer <NUM> via a plastic film that can be removed. Lithography and etching steps can be applied to form openings <NUM> in the top hat layer <NUM> at the locations of the printing fluid ejection chambers <NUM>.

In one example, the printing fluid ejection chambers <NUM> may eject the printing fluid <NUM> using a thermal resistor in the actuator <NUM>. For example, to eject the printing fluid <NUM>, a thermal resistor may heat a fluid in the printing fluid ejection chambers <NUM>. The heat may cause a steam bubble to be formed in the fluid and burst towards an opening of the printing fluid ejection chamber <NUM>. The printing fluid may be fed into the printing fluid ejection chambers <NUM> from the void <NUM> and the force of the bubble formation may cause a droplet of printing fluid <NUM> to be ejected from the printing fluid ejection chambers <NUM>.

It should be noted that the printhead <NUM> has been simplified for ease of explanation. The printhead die <NUM> may include additional components and circuitry that are not shown. For example, the printhead die <NUM> may include connection interfaces to a controller or other electronics, a housing, thin film dielectrics, thin film conductors, and the like.

Referring back to <FIG>, the printhead die <NUM> may be shipped with an adhesive tape <NUM> over each slotted portion <NUM> or a single piece of the adhesive tape <NUM> over all three slotted portions <NUM>. The adhesive tape <NUM> may be applied to prevent the printing fluid from leaking out of the openings <NUM> in the top hat layer <NUM> over the printing fluid ejection chambers <NUM> during shipping. However, when the adhesive tape <NUM> is removed before the printhead die is used, the adhesive tape <NUM> may damage the top hat layer <NUM>. For example, a portion of the top hat layer <NUM> can be damaged or torn by tape adhesive forces on the unsupported top hat layer portions of the top hat layer <NUM> causing the printing fluid <NUM> to leak from the chamber layer void <NUM>.

The present disclosure improves the initial unsupported top hat layer portion <NUM> to prevent damage during removal of the adhesive tape <NUM>. In one example, the initial unsupported top hat layer portion <NUM> may be soft or flexible and be damaged from removal of the adhesive tape <NUM>. However, the present disclosure forms the initial unsupported top hat layer portion <NUM> to minimize or significantly reduce the amount of deflection or stress applied to the top hat layer <NUM> when the adhesive tape <NUM> is removed. The amount of deflection created by the adhesive tape <NUM> may be a function of the width of a surface that is attached to the adhesive tape <NUM>.

<FIG> illustrates a more detailed view of the initial unsupported top hat layer portion <NUM>. The unsupported top hat layer portion <NUM> is formed to gradually increase a width (w<NUM>) from the first end <NUM> to a gradually wider width (w<NUM>) to a desired width (wd) at the second end <NUM>. In other words, wd > w<NUM> > w<NUM>. The widths w<NUM>, w<NUM>, and wd may also be referred to as the beam length of the top hat layer <NUM>.

The first end <NUM> may be an end where the adhesive tape <NUM> begins. The second end <NUM> may be where a desired width of the top hat layer <NUM> is reached and where the printing fluid ejection chambers <NUM> begin. The width, w<NUM>, of the first end <NUM> may be at a particular width that minimizes the amount of deflection of the adhesive tape <NUM> at a point of initiation of the adhesive tape <NUM> to the printhead die <NUM>.

The width is gradually increased until a desired width, wd, of the top hat layer <NUM> is reached. For example, the width of the first end <NUM> may be less than the width of the second end <NUM>. The first end <NUM> may be narrower than the second end <NUM>. Said another way, the first end <NUM> may be a narrow end and the second end <NUM> may be a wide end.

In one example, the first end <NUM> may have a beam length or a width that is approximately one tenth of a beam length or a width of the second end <NUM>. For example, the first end <NUM> may have a width of approximately <NUM>-<NUM> microns and the second end <NUM> may have a width of approximately <NUM>-<NUM> microns. In one example, the first end <NUM> may have a width of approximately <NUM> microns and the second end <NUM> may have a width of approximately <NUM> microns.

Said another way, the first end <NUM> of the initial unsupported top hat layer portion <NUM> may be tapered relative to the second end <NUM> of the initial unsupported top hat layer portion <NUM>. In one example, the side walls <NUM> of the initial unsupported top hat layer portion <NUM> (and corresponding portions of the chamber layer that form the walls <NUM>) may be formed at a particular angle θ from the first end <NUM> towards the second end <NUM>. The angle θ may be relative to an imaginary point where the two side walls <NUM> may meet if the walls were continued to the imaginary point, as shown by line <NUM> in <FIG>. In one example, the angle may be approximately <NUM> - <NUM> degrees. In one example, the angle may be approximately <NUM> degrees.

Thus, the form of the initial unsupported top hat layer portion <NUM> may allow the initial deflection and stress caused from the initial removal of the adhesive tape <NUM> to be minimized. Minimization of the deflection force may prevent damage to the initial unsupported top hat layer portion <NUM> as well as the remaining supported top hat layer portions of the top hat layer <NUM>. As the length of the adhesive tape <NUM> that is removed increases, the deflection force and stress may start to gradually increase as the beam length of the initial unsupported top hat layer portion <NUM> is increased. The gradually increasing stress may reduce failure rates compared with starting with a beam length of the unsupported top hat layer portion <NUM> that is large. Thus, the width of the initial unsupported top hat layer portion <NUM> is gradually increased up to the desired width of the second end <NUM> of the initial unsupported top hat layer portion <NUM>.

<FIG> illustrates a top view of an example of a slotted portion <NUM> of a printhead die. In one example, the slotted portion <NUM> may include a top hat layer <NUM> and a void <NUM> (shown as diagonal lines) formed in a portion of a chamber layer, and printing fluid ejection chambers <NUM> similar to the slotted portion <NUM>, illustrated in <FIG> and described above. The printing fluid ejection chambers <NUM> may be coupled to or formed on opposite sides of the fluid channel, and along a length of the walls <NUM>.

In one example, the slotted portion <NUM> may also include openings <NUM> in the top hat layer <NUM> over locations of the printing fluid ejection chambers <NUM>. The slotted portion <NUM> may also include the ink feed hole <NUM>.

The void <NUM> may be formed in the chamber layer to create a volume. The void <NUM> may store printing fluid <NUM>. The printing fluid <NUM> may be ejected by the printing fluid ejection chambers <NUM>, as described above. The slotted portion <NUM> may also include an initial unsupported top hat layer portion <NUM>.

The initial unsupported top hat layer portion <NUM> may also be formed to minimize deflection and/or stress caused by removal of adhesive tape applied to the slotted portion <NUM> before shipping. For example, the initial unsupported top hat layer portion <NUM> may also have a tapered shape or a trapezoidal shape, as described above in reference to the initial unsupported top hat layer portion <NUM> of the slotted portion <NUM>.

However, the slotted portion <NUM> may include pillars <NUM><NUM> to <NUM>I (hereinafter also referred to individually as a pillar <NUM> or collectively as pillars <NUM>). In one example, the pillars <NUM> may provide extra support. For example, the pillars <NUM> may provide a structure or surface to bond to the unsupported top hat layer portion <NUM>. This bond may further prevent the unsupported top hat layer portion <NUM> from being damaged when the adhesive tape <NUM> is removed.

In one example, the pillars <NUM> may be fabricated from the same material as the top hat layer <NUM> and the chamber layer. For example, the pillars <NUM> may also be fabricated from a photo definable polymer or negative photoresist material, such as SU8, for example.

In one example, the pillars <NUM> may have a diameter that is a function of a size of the slotted portion <NUM>. For example, the larger (e.g., width and length) the slotted portion <NUM> is, the larger the diameter of the pillars <NUM> may be. In one example, the diameter of the pillars <NUM> may be approximately <NUM>-<NUM> microns. In one example, the diameter of the pillars <NUM> may be approximately <NUM> microns.

In one example, the pillars <NUM> may have the same diameters. In one example, the pillars <NUM> may have different diameters.

In one example, some of the pillars <NUM> may be located in different areas of the initial unsupported top hat layer portion <NUM>. For example, the pillars <NUM><NUM> and <NUM><NUM> may be located towards a tip or first end of the initial unsupported top hat layer portion <NUM>. The pillars <NUM><NUM>-<NUM>I may be located through the void <NUM> closer to a second end of the initial unsupported top hat layer portion <NUM>.

<FIG> illustrates a cross-sectional view along a dashed line <NUM> illustrated in <FIG>. The cross-section view illustrates an example of the void <NUM> with the pillars <NUM>. In one example, the void <NUM> may be formed in the chamber layer to create a volume created by a surface of the substrate <NUM>, the side walls <NUM> of the chamber layer and the top hat layer <NUM>. The volume created by the void <NUM> may store a printing fluid <NUM>. The printing fluid <NUM> may be fed to each one of the printing fluid ejection chambers <NUM> during operation of the printhead die <NUM>.

As shown in <FIG>, the pillars <NUM> may be formed through the void <NUM>. The pillars <NUM> may be bonded to the top hat layer <NUM> and the surface of the substrate <NUM>. Thus, the pillars <NUM> help to further prevent the initial unsupported top hat layer portion <NUM> from being damaged, torn, pulled off, and so forth, when the adhesive tape <NUM> is removed from the slotted portion <NUM>.

It should be noted that although a particular arrangement of the pillars <NUM> is illustrated in <FIG> that the pillars <NUM> may be arranged in any shape or distribution. For example, more than two pillars may be arranged in the supported top hat layer portion of the top hat layer <NUM> and less than, or more than, five pillars <NUM> may be arranged in a regular or irregular pattern through the void <NUM> in the initial unsupported top hat layer portion <NUM>.

<FIG> illustrates a block diagram of other examples of initial unsupported top hat layer portions <NUM> of slotted portions of a printhead die of the present disclosure. For example, the slotted portions <NUM> and <NUM> illustrated in <FIG> and <FIG> illustrate an unsupported top hat layer portion <NUM> that has a trapezoidal shape with straight lined side walls <NUM>. The side walls <NUM> extend from the first end <NUM> to the second end <NUM> in a symmetrical form.

However, it should be noted that the side walls <NUM> between the first end <NUM> and the second end <NUM> may be formed in other shapes and forms. For example, the slotted portion <NUM> may have an initial unsupported top hat layer portion <NUM> formed by a top hat layer <NUM> over a void <NUM>. The initial unsupported top hat layer portion <NUM> may have side walls <NUM> that form a domed or "fire-hydrant" shape. For example, a first end <NUM> of the initial unsupported top hat layer portion <NUM> may have an initial width and then curve out gradually to a desired width.

In one example, a slotted portion <NUM> may have an initial unsupported top hat layer portion <NUM> formed by a top hat layer <NUM> over a void <NUM>. The initial unsupported top hat layer portion <NUM> may have side walls <NUM> that form multiple "points" on a first end <NUM>. For example, the initial unsupported top hat layer portion <NUM> may have an "M" shape or any other shape with multiple "points". Each point may have a width that gradually increases from the first end <NUM> and meets to a desired width.

In one example, a slotted portion <NUM> may have an initial unsupported top hat layer portion <NUM> formed by a top hat layer <NUM> over a void <NUM>. The initial unsupported top hat layer portion <NUM> may have irregular shaped side walls <NUM>. For example, the side walls <NUM> of the initial unsupported top hat layer portion <NUM> may have multiple curves as the width gradually increases from the first end <NUM> to a desired width.

It should be noted that the slotted portions <NUM>, <NUM>, and <NUM> illustrated in <FIG> are provided as additional examples and should not be considered limiting. For example, the initial unsupported top hat layer portion <NUM> of the printhead may have other shapes that are not illustrated in <FIG>, <FIG>, and <FIG>. For example, although the sidewalls are shown each having the same shape, the sidewalls of the initial unsupported top hat layer portion <NUM> may have different shapes. For example, one side wall may be straight and the opposite side wall may have a curve or an irregular shape.

In one example, the shape of the initial unsupported top hat layer portion <NUM> may be a function of other components in the printhead. For example, the printhead may have a deflection plate or other component that may be covered by the initial unsupported top hat layer portion <NUM>. Thus, the unsupported top hat layer portion <NUM> may have a gradual increase in width from a first end as long as all of the components within the respective slotted portion of the printhead die are covered by the initial unsupported top hat layer portion <NUM>.

<FIG> illustrates a flow diagram of an example process flow <NUM> for fabricating a printhead die of the present disclosure. In an example, the process flow <NUM> may be performed by different tools or equipment that are operated individually or collectively by a single controller or processor.

At block <NUM>, the method <NUM> begins. At block <NUM>, the method <NUM> provides a substrate. For example, substrate may be a silicon wafer and may include integrated circuit thin films and processes. Each silicon wafer may be processed to form multiple printhead dies. In one example, an ink feed hole may be etched out of the substrate to allow printing fluid to enter the printhead die.

At block <NUM>, the method <NUM> deposits a first layer of photo definable polymer onto the substrate. The photo definable polymer may be a negative photo resist material such as SU8. The photo definable polymer material may be deposited onto portions of the printed circuit board where the printheads may be formed. The first layer of photo definable material may form the chamber layer.

At block <NUM>, the method <NUM> applies a mask to the first layer of the photo definable polymer to form a void. For example, the mask may be applied to the first layer to define areas in the photo definable polymer where the void to store printing fluid will be formed.

At block <NUM>, the method <NUM> performs photolithography and etching processes to form the void in the first layer of the photo definable polymer. For example, the photolithography steps may include exposing portions of the photo definable polymer to certain types of light. The etching process may include wet etch and/or dry etch processes to remove the portions of the photo definable polymer that are exposed to the light. In one example, the etching process may include wet etch and/or dry etch processes to remove the portions of the photo definable polymer that were not exposed to the light.

In one example, the remaining portions of the chamber layer may form the walls to support portions of a subsequently deposited top hat layer. In one example, pillars may also be formed in the first layer of the photo definable polymer. For example, the pillars may be formed via a masking, photolithography, and etching processes. The pillars may provide a surface to bond to an initial unsupported top hat layer portion that is formed, as discussed above. The bond may provide more support to the initial unsupported top hat layer portion, and as such may reduce occurrences of damage to the top hat layer when adhesive tape applied to the slotted portion is removed.

At block <NUM>, the method <NUM> deposits a second layer of the photo definable polymer over the first layer of the photo definable polymer. For example, the second layer of the photo definable polymer may be pushed onto the previously deposited chamber layer using a plastic film to form a top hat layer. According to the invention, the top hat layer is much thinner than the chamber layer.

In one example, the portions of the top hat layer that rest on the remaining walls of the chamber layer may form supported or rigid portions of the top layer. The portions of the top hat layer that sit over a void formed in the chamber layer may form unsupported portions of the top hat layer.

At block <NUM>, the method <NUM> may apply photolithography and etching steps to form openings in the second layer of the photo definable polymer over each printing fluid ejection chamber and to form an initial unsupported top hat layer portion that is tapered. For example, the initial unsupported top hat layer portion may be formed with the first end at an initial width. The side walls of the initial unsupported top hat layer portion may gradually move away from one another to form a second end having a second width. The second width may be greater than the first width. The second width may be a desired width of the top hat layer of the printhead die. The chamber layer may also be etched to have an end that has a tapered portion that matches the shape of the initial unsupported top hat layer portion in block <NUM>.

Claim 1:
A printhead die (<NUM>), comprising:
a substrate (<NUM>) comprising one or more slotted portions (<NUM>);
wherein each of the one or more slotted portions comprises (<NUM>):
a chamber layer (<NUM>) formed on the substrate (<NUM>), wherein the chamber layer (<NUM>) comprises a void (<NUM>) to store printing fluid, wherein the void (<NUM>) runs along a length of the corresponding slotted portion (<NUM>);
a plurality of printing fluid ejection chambers (<NUM>) coupled to opposite sides of the void (<NUM>) and along a length of the chamber layer (<NUM>); and
a top hat layer (<NUM>) formed on the chamber layer (<NUM>) and the plurality of printing fluid ejection chambers (<NUM>), wherein the top hat layer (<NUM>) comprises an unsupported top hat layer portion over the void (<NUM>), wherein an initial portion (<NUM>) of the unsupported top hat layer portion has a width across the unsupported top hat layer portion that gradually increases from a first width (w<NUM>) at a first end (<NUM>) of the initial portion (<NUM>) of the unsupported top hat layer portion to a second width (wd) at a second end (<NUM>) of the initial portion (<NUM>) of the unsupported top hat layer portion, wherein said first and second ends (<NUM>, <NUM>) are separated along the length of the corresponding slotted portion (<NUM>);
characterized in that the top hat layer (<NUM>) and the chamber layer (<NUM>) are made of the same material; and
in that the top hat layer (<NUM>) is a photo definable polymer layer thinner than the chamber layer (<NUM>).