MX2008008236A - Low energy, long life micro-fluid ejection device - Google Patents

Abstract

Micro-fluid ejection heads and methods for extending the life of micro-fluid ejection heads. One such micro-fluid ejection head includes a substrate having a plurality of thermal ejection actuators. Each of the thermal ejection actuators has a resistive layer and a protective layer thereon. A flow feature member is adjacent the substrate and defines a fluid feed channel, a fluid chamber associated with at least one of the actuators and in flow communication with the fluid feed channel, and a nozzle. The nozzle is offset to a side of the chamber opposite the feed channel. A polymeric layer having a degradation temperature of less than about 400°C. overlaps a portion of the at least one actuator associated with the fluid chamber and positioned less than about five microns from at least an edge of the at least one actuator opposite the fluid feed channel.

Description

LONG-LIFE AND LOW-POWER MICRO-FLUID EXPULSION DEVICE FIELD OF THE INVENTION The description refers to micro-fluid ejection devices and in a particular modality, to long-lasting and low-energy devices, to eject small droplets of liquid.

BACKGROUND OF THE INVENTION Micro-fluid ejection devices are classified by a mechanism used to expel fluid. Two of the most important types of micro-fluid ejection micro-devices include thermal actuators and piezoelectric actuators;; The thermal actuators depend on the ability to heat the fluid to a core forming temperature where a gas bubble is formed which expels the fluid through a nozzle. The duration of such thermal actuators depends on a number of factors including, but not limited to, dielectric breakdown, corrosion, fatigue, electromigration, contamination, thermal mismatch, electrostatic discharge, delamination material compatibility, and humidity, to name a few. A thermal resistor used in a micro-fluid ejection device can be exposed for all these failure mechanisms. For example, it is well known that cavitation pressures are powerful enough to strike through any solid material, from concrete dams to ship propellers. During each fire cycle, the thermal resistor can be exposed to similar cavitation impacts. When the gas bubble collapses, a local pressure of about 10J to 104 atmospheres is generated. Such cavitation impacts can be focused on a submicron point of the thermal resistor for several nanoseconds. After 107 to 108 cavitation impacts, the thermal resistor may fail due to mechanical erosion. In addition, because the thermal resistor requires extremely high temperatures to ensure the formation of homogeneous bubble core, a distortion energy in the heater attributable to the thermal expansion can be generated in the same order of importance as the distortion energy due to the collapse of the bubble. A combination of thermal expansion and cavitation impacts can result in premature heater failure. To protect the fragile thermal resistor films, the films can be hermetically sealed to prevent corrosion caused by moisture, but the surface of the thermal resistor is directly exposed to the liquid. In the most critical areas of the heater, a smaller surface opening due to defect, wear, pitch coverage, or delamination may result in a catastrophic failure of the thermal resistor. Therefore, the exotic resistor films and the multiple protective layers that provide a thermal battery are used to supply the thermal resistors robust enough to withstand the cavitation and thermal expansion abuses described above. However, the overall thickness of the thermal cell must be minimized because the input energy is a linear function of the thermal cell thickness. To provide competitive actuating devices for power dissipation and flow perspective production, the thermal battery should not be arbitrarily swelled to mitigate the effects of cavitation, overcome pass coverage issues, overcome delamination problems, reduce discharge electrostatic, etcetera. In other words, the reliability of the thermal resistor enhanced by the over-design of the protective and resistive thin film layers can result in a non-competitive product. Micro-fluid ejection micro-heads can be classified as permanent, semi-permanent or disposable. The protective films used in the thermal resistors of the disposable micro-fluid ejection heads need only last until the fluid in the coupled fluid cartridges is depleted. The installation of a fluid cartridge involves the installation of a new fluid ejection micro-head. A more difficult problem of the duration of the thermal resistor is presented for permanent or semi-permanent micro-fluid ejection heads. There is a need, therefore, for a method and apparatus for improving the duration of the thermal resistor without renouncing jet measurements and energy consumption.

SUMMARY OF THE INVENTION With respect to the foregoing, the exemplary embodiments of the description provide micro-fluid ejection heads having a long duration and relatively low energy consumption and methods for making micro-fluid ejection heads with prolonged duration and consumption. of relatively low energy. Such a fluid ejection micro-head includes a substrate having a plurality of thermal ejection actuators placed therein. Each of the thermal ejecting actuators includes a resistive layer and a protective layer to protect a surface of the resistive layer. Together the resistive layer and the protective layer define a thickness of the actuator stack. A circulation characteristic element is adjacent (eg, coupled to) the substrate and defines a fluid supply channel, a fluid chamber associated with at least one of the thermal ejection actuators and in flow communication with the channel of fluid feed, and a nozzle. The nozzle is balanced on one side of the fluid chamber opposite the fluid feed channel. A polymeric layer having a degradation temperature of less than about 400 ° C overlaps a portion of at least one thermal ejection actuator, and is placed at less than about five microns from at least one edge of at least one actuator opposite the fluid feed channel. In another embodiment, a method is provided for prolonging the duration of a thermal ejection actuator for a fluid ejection micro-head. A substrate has a plurality of thermal ejection actuators and a protective layer therefor deposited therein, and has a circulation characteristic element defining a fluid supply channel, a fluid chamber related at least to one of the thermal ejection actuators and in the flow communication with the fluid feed channel, and a nozzle. The nozzle is compensated on one side of the distal fluid chamber from the fluid supply channel. The method comprises depositing a polymeric layer having a degradation temperature of less than about 400 ° C in overlapping relationship with at least a portion of at least one thermal ejecting actuator. The polymer layer overlaps less than about five microns of at least one actuator adjacent to a distal edge thereof of the fluid supply channel. An advantage of at least some of the exemplary embodiments of the description is that thermal energy does not increase while the duration of the actuators improves considerably. Another poial advantage of at least some of the described modes is the ability to change the duration of an ejector actuator without significantly changing the energy requirements for ejecting fluids.

BRIEF DESCRIPTION OF THE FIGURES The additional advantages of the modalities will be evident by reference to the detailed description of the exemplary modalities when considered together with the figures, in which similar reference characters indicate similar elements: or similar through several figures as follows: Figure 1 is a cross-sectional view, not to scale, of a portion of a fluid ejection micro-head of the prior art; Figure 2 is a graphical representation of jet injection energy versus the thickness of protective layer for micro-fluid ejection heads; Figure 3 is a photomicrographic plane view of a fluid ejection micro-actuator of the prior art having a cavitation damage therein; Figure 4 is a photomicrographic cross-sectional view of a prior art fluid ejecting micro actuator having cavitation damage thereto; Figure 5 is a plan view, not to scale, of a portion of a fluid ejection micro-head of the prior art; Figure 6 is a cross-sectional view, not to scale, of a portion of a fluid ejection micro-head according to a first embodiment of the description; Figure 7 is a plan view, not to scale, of a portion of a micr D-fluid ejection head according to the first embodiment of the description; Figure 8 is the temperature profile for a fluid ejecting micro-actuator in accordance with the description; Figure 9 is a cross-sectional view, not to scale, of a portion of a fluid ejection micro-head in accordance with a second embodiment of the description; Figure 10 is a plan view, not to scale, of a portion of a fluid ejection micro-head according to the second embodiment of the description; and Figure 11 is a perspective view, not to scale, of a fluid cartridge for a fluid ejection micro-head in accordance with the description.

DETAILED DESCRIPTION OF THE INVENTION In accordance with the embodiments described in the present invention, micro-fluid ejection heads that have improved energy consumption and prolonged duration will now be described. For purposes of this description, the terms "thermal battery", "ejector stack", and "actuator stack" are intended to refer to an ejection actuator having a combined layer thickness of a layer of resistive material and the passivation or layer of protective material. The pssivation or layer of protective material is applied to a surface of the layer of resistive material to protect the actuator from, for example, chemical or mechanical corrosion or erosion effects of the fluids expelled by the micro-ejection device. fluid. To more fully appreciate the benefits of exemplary embodiments, reference is made to FIG. 1, which is a cross-sectional view, not to scale, of a portion of a fluid ejection micro-head 10 of the prior art. The cross-sectional view of figure 1 shows a fluid ejection micro-actuator 12 contained in a fluid ejection micro-head. Ejector actuators 12 are formed on a substrate 14. Substrate 14 can be made from a wide variety of materials including plastics, ceramics, glass, silicon, semiconductor material, and the like. In the case of a substrate of semiconductor material, a layer of thermal insulation 16 is applied to the substrate between the substrate 14 and the ejection actuators 12. The ejection actuators 12 can be formed of a layer of electrically resistive material 18, such as TaAl, Ta2N, TaAl (0, N), TaAlSi, TaSiC, Ti (N, 0), WSi (0, N), TaAlN, and TaAl / Ta. The thickness of the layer of resistive material 18 can be extended from about 300 to about 1000 angstroms. The thermal insulator layer 16 can be formed of a thin layer of silicon dioxide and / or silicon glass with additive to coat the relatively thick substrate 14. The total thickness of the thermal insulator layer 16 can be extended from about 1 to about 3 microns thick. The underlying substrate 14 may have a thickness extending from about 0.2 to about 0.8 millimeters in thickness. A protective layer 20 covers the ejection micro-actuators 12. The protective layer 20 can be a layer of a SOJ.O material or a combination of layers of various materials.In the illustration of FIG. The protective layer 20 includes a first passivation layer 22, a second passivation layer 24, and a cavitation layer 26. The protective layer 20 is effective in preventing fluid or other contaminants from adversely affecting the operation and electrical properties of the devices. fluid ejection actuators 12 and provide protection from mechanical abrasion or shock due to collapse of the fluid bubble The first passivation layer 22 can be formed of a dielectric material, such as silicon nitride, or diamond-like carbon with silicon additive (Si-DLC) having a thickness ranging from about 1000 to about 3200 angstroms in thickness The second passivation layer 24 can also be formed from n Dielectric material, such as silicon carbide, silicon nitride, or diamond-like carbon with silicon additive (Si-DLC) having a thickness ranging from about 500 to about 1500 angstroms in thickness. The combined thickness of the first and second passivation layers 22 and 24 typically extends from about 1000 to about 5000 angstroms. The cavitation layer 26 is typically formed of tantalum having a thickness greater than about 500 angstroms in thickness. The cavitation layer 26 can also be made of TaB, Ti, T W, TiN, WSi, or any other material with a similar thermal capacitance and relatively high hardness. The maximum thickness of the cavitation layer 26 is such that the total thickness of the protective layer 20 is less than about 7200 angstroms in thickness. The total thickness of the protective layer 20 is less defined as a distance from an upper surface 28 of the material resistive layer 18 to an outermost surface 30 of the protective layer 20. The thickness of the ejector stack 32 is defined as the combined thickness of the layers 18 and 20. The ejecting actuator 12 is defined by depositing and etching a conductive metal layer 34 in the resistive layer 18 to provide ground and current conductors 34A and 34B as illustrated in FIG. 1. conductive layer 34 is typically selected from conductive metals, including but not limited to, gold, aluminum, silver, copper, and the like and has a range that ranges from about 4,000 to about 15,000 angstroms. The coating of the earth and current conductors 34A and 34B is another layer of insulator or dielectric layer 36 typically composed of photoresist epoxy materials, polyimide materials, silicon nitride, silicon carbide, silicon dioxide, spin on glass (SOG per its acronym in English) rotated in glass, laminated polymer and the like. The insulator layer 36 and has a thickness ranging from about 5,000 to about 20,000 angstroms and provides insulation between a second metal layer and the conductive layer 34 and corrosion protection of the conductive layer 34. Layers 14, 16, 18 , 20, 34, and 36 provides a semiconductor substrate 40 for use in the fluid ejection micro-head 10. A nozzle plate 42 is adjacent (eg, coupled, such as by an adhesive 44) to the semiconductor substrate 40. In the prior art embodiment illustrated in Figure 1, the nozzle plate 42 contains nozzles 46 which correspond to the respective ones of the plurality of ejection actuators 12. During a fluid ejection operation, a fluid in fluid chamber 48 it is heated by the ejection actuators 12 to a core forming temperature of approximately 325 ° C. To form a fluid bubble which expels fluid from the fluid chamber 48 through the nozzles 46. A fluid supply channel 50 supplies fluid to the fluid chamber 48. A disadvantage of the fluid ejection micro-head 10 described above is that the multiplicity of the protective layers 20 within the fluid ejection micro-head 10 increases the thickness of the ejection stack 32, thereby increasing a general injection energy required to eject a drop of fluid at through the nozzles 46. Once the ejecting actuator 12 is activated, some of the energy ends up as wasted thermal energy used to heat the protective layer 20 by conduction, while the rest of the energy is used to heat the fluid adjacent the surface 30 of the cavitation layer 26. When the surface 30 reaches a superheat limit of fluid, a vapor bubble forms. As soon as the vapor bubble is formed, the fluid is thermally disconnected from the surface 30. Therefore, the vapor bubble prevents the transfer of additional thermal energy to the fluid. The thermal energy transferred in the fluid, before the bubble formation, is the one that leads the change of state from liquid to vapor of the fluid. Since the thermal energy must pass through the protective layer 20 before heating the fluid, the protective layer 20 is also heated. Heating the protective layer 20 takes a finite amount of energy. The amount of energy required to heat the protective layer 20 is directly proportional to the thickness of the protective layer 20 and the thickness of the resistive layer 18. An illustrative example of the relationship between the thickness of the protective layer 20 is shown in Figure 2. and the injection energy required for a specific size of ejector actuator 12. The injection energy is related to the power (power that is a product of the energy and the firing frequency of the fluid ejection micro-actuators 12). The temperature increase experienced by the substrate 40 is also related to energy. The fluid characteristics and sufficient ejection performance, such as the print quality in the case of an ink ejection device, are related to the temperature rise of the substrate 40. For the disposable micro-fluid ejection heads, the Thickness of protective layer 20 can be minimized to reduce energy consumption. However, for longer duration micro-fluid ejection heads, such as permanent or semi-permanent ejector heads, which increase the thickness of the protective layer 20 to extend the life of the ejection heads can adversely affect the energy consumption. of the ejection heads as described above. For example, a disposable ejection head can provide up to approximately 10 million ejection cycles before the ejection head fails. However, longer-term ejection heads may require up to 1 billion ejection cycles or more before failure. Accordingly, methods and apparatuses can be provided to prolong the life of the heads without adversely affecting the ejection energy requirements, such as by the following exemplary embodiments.

As described above, the thermal expansion distortions and the cavitation impacts are combined to reduce the duration of the fluid ejection micro-actuators. Figures 3 and 4 show evidence of the cavitation and thermal expansion target effects shown in the photomicrographs of the fluid ejection micro-actuators of the prior art. Figure 3 is a plan view of a fluid ejection micro-actuator 52 of the prior art showing a wear pattern 54 adjacent the distal edge 56 of the fluid supply channel 50 (Figure 1). Figure 4 is a cross-sectional view of a fluid ejection micro-head 58 showing the erosion pattern adjacent the edge 56 of the fluid ejection micro-actuator 52 of the prior art. As more clearly shown in Fig. 5, the fluid ejecting micro-actuator 52 of the prior art is an elongate thermal resistor having a length L greater than an amplitude W. Typically the actuator 52 has a length of component. at width ranging from about 1.5: 1 to about 3: 1. The general heating area of the actuator 52 can be extended from about 200 square micras to about 1200 square micras.

A nozzle 60 can be biased toward the distal edge 56 of the fluid ejecting micro-actuator 52, such as to reduce entrapment of air in the fluid chamber 48 (Figure 1). However, diverting the nozzle 60 towards the distal edge 56 increases the damage by cavitation and thermal expansion adjacent the distal edge 56 of the fluid ejection micro-actuator, as shown in FIGS. 3 and 4. The methods and methods will now be described. apparatuses to reduce or eliminate the damage by thermal expansion and cavitation for the fluid ejection micro-actuators with reference to figures 6-9. Figure 6 is a cross-sectional view, not to scale, of a fluid ejection micro-head 70 according to a first embodiment of the description. In this embodiment, the ejection head 70 includes a circulation feature element 72 coupled, either by an adhesive 74, adjacent (e.g., a) to a semiconductor substrate 76. The circulation feature element 72 has a thickness that is extends from about 5 to 65 microns, and can be made from a chemically resistant polymer such as polyamide. Circulation characteristics, such as a fluid chamber 78, a fluid supply channel 80 and a nozzle 82, can be formed in the circulation feature element 72 by conventional techniques, such as laser ablation. The embodiments described in the present invention are not limited by the preceding circulation feature element 72. In an alternative embodiment, the circulation feature element may comprise fluid chambers and the fluid supply channel in a thick film layer at the which a nozzle plate is coupled, or the flow characteristics can be formed both from a thick film layer and from a nozzle plate. Figure 9, described below, illustrates an embodiment of a fluid ejection micro-head 84 having a thick film layer head and a nozzle plate 88 coupled to the thick film layer 86. The semiconductor substrate 76 to which the circulation feature element 72 includes a support substrate 90 made of an insulating or semiconducting material as described above with reference to Figure 1. In the case of a semiconductor material for the substrate 90, an insulating layer 92 similar to the insulating layer 16, it is applied to the substrate 90. A resistive layer 94 similar to the resistive layer 18, described above, is applied to the insulating layer 92. Likewise, a conductive layer 96 similar to the layer conductive 34, applies to the resistive layer 94 and is recorded to supply the power and ground conductors 96A and 96B to activate a fluid ejection micro-actuator 98 that is defined between the conductors 96 A and 96B. An advantage of at least some of the described embodiments is that the number and thickness of the protective layers of the fluid ejection micro-actuator 98 can be reduced to reduce energy consumption without adversely affecting the duration of the micro-actuators of fluid ejection 98. Unlike the ejection head 10 illustrated in figure 1, the ejection head 70 has a single protective layer 100 and, optionally, a relatively thin layer of cavitation 102. The protective layer 100 can be provided by a material that is selected from the group consisting of diamond-like carbon (DLC), diamond-like carbon with silicon additive (Si-DLC), titanium, tantalum, silicon nitride and a rusty metal The thickness of the protective layer 100 can be extended from about 400 to about 3000 angstroms. Such a thickness of protective layer 72 provides a stack of ejection actuators 104 having a thickness extending from about 1200 to about 6500 angstroms. When used, the cavitation layer 102 can have a thickness ranging from about 500 to about 3000 angstroms.

To, for example, reduce the damage caused by thermal expansion and adjacent cavitation a distal edge 106 of the fluid ejection micro-actuator 98, a polymeric layer 108 having a degradation temperature of less than about 400 ° C. it is applied to the protective layers 100 and 102 and to the conductive layer 96 so that the polymeric layer overlaps a portion of the fluid ejection micro-actuator 98 as shown in the plan view of Figure 7 adjacent the distal edge 106 thereof. . Due to the relatively low degradation temperature of the polymeric layer 108, the overlapped portion of the actuator 98 must be less than about five microns. Typically, the overlapped portion of the actuator 98 extends from about one to about four microns. In Figure 8 a temperature profile for the fluid ejection micro-actuator 98 is shown by the curve A. As shown in Figure 8, the fluid ejection micro-actuator 98 has a temperature of about 400 ° C. in a central portion of the actuator while, the edge 106 of the actuator has a temperature of about 150 ° C. At about five microns from edge 106 of actuator 98, at point B on curve A, the temperature is about 325 ° C which is the core formation temperature indicated by dotted line 110 to eject fluid from the micro- fluid ejection head 70. Therefore, if less than five microns of the actuator 98 are lapped at the adjacent edge 106 with the polymeric layer 108, the polymeric layer may be below its decomposition temperature. An appropriate polymeric layer 108 having a degradation temperature below about 400 ° C is of an epoxy-entangled resin material as described in US Pat. No. 6,830,646 to Patil et al., Description of which is included by reference in the present invention. The polymeric layer 108, in the case of the fluid ejection micro-head 70, can be applied as a planarization layer having an average thickness of about one to about ten microns. Spray coating, submerging, or spinning processes can be used to apply the polymeric layer 108 to the conductive layer 96 and the protective layers 100 and 102. It will be appreciated that the overlapping portion of the actuator 98 may have a thickness greater than polymer layer 108 so that a relatively smooth planarization layer can be obtained. With reference to Figures 9 and 10, alternative embodiments of the description will be described. As stated above, the fluid ejection micro-head 84 illustrated in FIGS. 9 and 10 includes a layer of thick film 86 to provide the circulation feature element containing a fluid chamber 120 and a fluid supply channel. 122. The thick film layer 86 can also be made of an epoxy-entangled resin material as set forth above. However, the thick film layer 86 has a thickness ranging from about 4 to about 40 microns or more. As with the polymeric layer 108, the thick film layer overlaps a portion of the fluid ejection micro-actuator 98 as shown in Figures 9 and 10. The overlapping portion adjacent the distal edge 106 may also be less than about five microns and can range from approximately one to approximately four micras. The thick film layer 86 can be made from the same material of the polymeric layer 108; in which case there may not be any need for a polymeric layer 108 between the thick film layer 86 and the conductive layer 96 and the protective layers 100 and 102. The thick film layer 86 may be applied in the same manner as the polymeric layer 108 described above. Each of the polymeric layer 108 and the thick film layer 86 can be photographed and developed utilizing conventional photography and development techniques to provide less than five microns of the actuator 98. In the case of the thick film layer 86, photography and development techniques can also be used to provide the fluid chamber 120 and the fluid supply channel 122 therein. After photographing and revealing the thick film layer 86, a nozzle plate 88 made of a polyamide material or a photo material resistant to the thick film layer 86 can be coupled. In the case of a polyamide nozzle plate 88 , a nozzle 124 can be made by laser ablation for each of the actuators in the nozzle plate 88. If the nozzle plate 88 is made of a photo-resistant material, the photography and development techniques can be used to make the nozzle 124. In another alternative embodiment, as illustrated in Figures 9 and 10, a polymeric layer 126 may overlap a proximal edge 128 of the actuator 98 so that both the distal edge 106 and the proximal edge 128 of the actuator 98 overlap. less than about five microns, typically from about one to about four microns. The polymeric layer 126, as illustrated in Figures 9 and 10, can be applied equally to overlap the proximal edge 128 of the actuator illustrated in Figures 6 and 7. In the embodiment illustrated in Figures 9 and 10, the polymeric layer 126 it can be the same as the thick film layer 86 except that the thickness of the polymeric layer 126 will be reduced in the fluid supply channel 122 of the ejection head 84 to the photograph and reveal the polymeric layer 126. The micro-head of fluid ejection 70 or 84 can be attached permanently or removably to a fluid supply cartridge 128 as shown in Figure 11. As shown in Figure 5, the ejection head 70 or 84 can be attached to a ejection head portion 130 of the fluid cartridge 128. A main body 132 of the cartridge 128 includes a fluid supply reservoir to the fluid ejection micro-head 70 or 84. A flexible circuit or automated link circuit by tape 134 ( ) which contains electrical contacts 136 for connection of an ejection head control device, such as an inkjet printer, which is coupled to the main body 132 of the cartridge 128. electrical tracking 138 of the electrical contacts 136 is coupled to the substrate 76 (Figures 6 and 9) to provide activation of the fluid ejection micro-actuator 98 at the request of the control device to which the fluid cartridge 128 is coupled. The description , however, it is not limited to the fluid cartridges 128 as illustrated in Figure 11 as a fluid ejection micro-head 70 or 84 in accordance with the description can be used for a wide variety of fluid cartridges, wherein the ejecting head 70 or 84 may be remote from the main body fluid reservoir 128. It will be considered, and will be apparent to those skilled in the art of the foregoing description and appended figures. Thus, modifications and changes in the modalities of the description can be made. Therefore, it is expressly intended that the foregoing description and the appended figures are illustrative of the exemplary embodiments only, not restrictive thereto, and that the true spirit and scope of the present disclosure are determined by reference to the appended claims.

Claims (20)

NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, the content of the following is claimed as property: CLAIMS

1. - A fluid ejection micro-head, comprising: a substrate having a plurality of thermal ejection actuators placed therein, each of the thermal ejection actuators includes a resistive layer and a protective layer to protect a surface of the resistive layer, together the resistive layer and the protective layer define a thickness of the actuator stack; a flow characteristic element adjacent to the substrate defines a fluid supply channel, a fluid chamber associated with at least one of the thermal ejection actuators and in flow communication with the fluid supply channel, and a nozzle, wherein the nozzle is diverted to a fluid chamber opposite the fluid feed channel; and a polymeric layer having a degradation temperature of less than about 400 ° C which overlaps a portion of at least one thermal ejection actuator associated with the fluid chamber and placed less than about five microns from at least one edge of the fluid chamber. at least one actuator opposite the fluid feed channel.

2. The fluid ejection micro-head according to claim 1, characterized in that the stack thickness of the actuator extends from approximately 1200 to approximately 6500 angstroms and provides an ejection energy per unit volume from approximately 2 to approximately 4 giga joule per cubic meter.

3. The fluid ejection micro-head according to claim 1, characterized in that the resistive layer has a thickness ranging from approximately 300 to approximately 1000 angstroms.

4. - The fluid ejection micro-head according to claim 1, characterized in that each of the thermal ejection actuators has a fluid heating area that extends from approximately 200 square microns to approximately 1200 microns square

5. The fluid ejection micro-head according to claim 1, characterized in that the protective layer has a thickness ranging from approximately 900 to approximately 5500 angstroms.

6. - The fluid ejection micro-head according to claim 1, characterized in that the resistive layer comprises a tantalum-aluminum alloy and the protective layer comprises a material selected from the group eme consisting of carbon similar to diamond , carbon similar to diamond with silicon additive, silicon nitride, titanium, tantalum, and a layer of oxidized metal.

7. The fluid ejection micro-head according to claim 6, characterized in that the resistive layer comprises a material that is selected from the group consisting of tantalum-aluminum (TaAl), tantalum-nitride (TaN), tantalum -aluminium-nitride (TaAl: N), and layers composed of tantalum and tantalum-aluminum (Ta + TaAl).

8. The fluid ejection micro-head according to claim 1, characterized in that the polymer layer comprises an epoxy-crosslinked resin material.

The fluid ejection micro-head according to claim 1, characterized in that the polymer layer overlaps an edge of at least one actuator in an amount ranging from about 1 to about 4 microns.

10. - The fluid ejection micro-head according to claim 1, characterized in that the polymer layer overlaps at least one ejection actuator adjacent to the opposite edges thereof in an amount ranging from about 1 to about 4 microns.

11. The fluid ejection micro-head according to claim 1, characterized in that the actuators are elongated actuators having a width to length ratio ranging from approximately 1.5: 1 to approximately 5: 1.

12. A method for extending the duration of a thermal ejection actuator for a fluid ejection micro-head comprising a substrate having a plurality of thermal ejection actuators and a protective layer deposited therein., and has a fluid characteristic element defining a fluid feed channel, a fluid chamber associated with at least one of the thermal ejection actuators and in flow communication with the fluid feed channel, and a nozzle , wherein the nozzle is diverted to one side of the distal fluid chamber from the fluid supply channel, the method characterized in that it comprises: depositing a polymeric Cc.pa having a degradation temperature of less than about 400 ° C in relation to of overlap with at least one portion of the at least one thermal ejection actuator wherein the polymer layer overlaps less than about five microns of at least one stirrer adjacent a distal edge thereof from the fluid feed channel.

13. The method according to claim 12, characterized in that the fluid characteristic element comprises a layer of polymeric thick film.

14. The method according to claim 13, characterized in that the act of depositing a polymer layer provides the polymeric thick film layer.

15. The method according to claim 12, characterized in that the fluid feature element comprises a unitary polyamide member having fluid feed channels, fluid chambers, and nozzles.

16. The method according to claim 15, characterized in that the polymer layer comprises a planarization layer having a thickness ranging from about 1 to about 6 microns.

17. - The method according to claim 16, characterized in that the planarization layer comprising: an epoxy-crosslinked resin material.

18. The method according to claim 12, characterized in that the polymer layer is deposited so that the polymer layer overlaps opposite edge portions of at least one actuator.

19. The method according to claim 18, characterized in that the polymer layer is deposited at least :; in an actuator so that the overlapping portions extend from about 1 to about 4 microns from the opposite edge portions thereof.

20. A micro-fluid ejection head manufactured in accordance with the method of claim 12.