Abstract:
A method for creating one or more ink jet chambers, the method includes the steps of providing a substrate having a thermal element covered with substantially one type of uncured photo-imageable material; providing a first mask spanning the thermal element which creates both masked and unmasked uncured photo-imageable regions; exposing the unmasked photo-imageable region; providing a second mask covering at least a portion of the thermal element; exposing a portion of the remaining unexposed photo-imageable region for forming an output nozzle; curing the exposed portions of the photo-imageable material; and removing all the remaining uncured photo-imageable material for creating the ink jet chamber.

Description:
FIELD OF THE INVENTION  
       [0001]     The invention relates generally to the field of ink jet recording heads, and in particular to a method of manufacturing an ink jet chamber. More specifically, the invention relates to the manufacture of specific ink jet chambers that enhance the performance of the ink jet recording process.  
       BACKGROUND OF THE INVENTION  
       [0002]     An ink jet recording head typically includes outlets or nozzles that serve to eject tiny droplets of liquids used in a recording process onto a media, such as any suitable paper. Situated behind those nozzles is a chamber that contains either ink or fluid and a mechanism of either electrically or mechanically ejecting the ink or fluid onto a suitable receiver.  
         [0003]     A more conventional method of manufacturing an ink jet recording head is represented in U.S. Pat. No. 5,478,606 by Ohkuma et. al., wherein a method of manufacturing an ink jet recording head has the steps of (1) forming an ink flow path pattern on a substrate with the use of a dissoluble resin, the substrate having ink ejection pressure generating elements thereon; (2) forming on the ink flow path pattern a coating resin layer, which will serve as ink flow path walls, by dissolving in a solvent a coating resin containing an epoxy resin which is solid at ordinary temperatures, and then solvent-coating the solution on the ink flow path pattern; (3) forming ink ejection outlets in the coating resin layer above the ink ejection pressure generating elements; and (4) dissolving the ink flow path pattern.  
         [0004]     Consequently, a need exists for forming a ink jet chamber which reduces complexity, reduces manufacturing steps and lowers costs.  
       SUMMARY OF THE INVENTION  
       [0005]     The present invention is directed to overcoming one or more of the problems set forth above. Briefly summarized, according to one aspect of the present invention, a method is detailed for the creation of one or more ink jet chambers, the method comprising the steps of providing a substrate having a thermal element covered with substantially one type of uncured photo-imageable material; providing a first mask spanning the thermal element which creates both masked and unmasked uncured photo-imageable regions; exposing the unmasked photo-imageable region; providing a second mask covering at least a portion of the thermal element; exposing a portion of the remaining unexposed photo-imageable region for forming an output nozzle; curing the exposed portions of the photo-imageable material; and removing all the remaining uncured photo-imageable material for creating the ink jet chamber.  
         [0006]     The above and other objects of the present invention will become more apparent when taken in conjunction with the following description and drawings wherein identical reference numerals have been used, where possible, to designate identical elements that are common to the figures.  
       ADVANTAGEOUS EFFECTS OF THE INVENTION  
       [0007]     The present invention has the following advantages in that a thermal element covered with substantially one type of uncured photo-imageable material is used in the creation of an ink jet chamber. This method when considered over the prior art provides significant advantage in reduced complexity, reduced manufacturing steps and lower costs. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]      FIG. 1  is a side view of an ink jet chamber of the present invention positioned upon a substrate, showing the creation of features by exposing a photo-imageable material through a first mask;  
         [0009]      FIG. 1   a  is a side view of an ink jet chamber of the present invention situated upon a substrate, showing the creation of features by exposing a photo-imageable material through a second mask;  
         [0010]      FIG. 1   b  is a side view of an ink jet chamber of the present invention situated upon a substrate, showing finished features after curing and removal of uncured and unexposed photo-imageable material;  
         [0011]      FIG. 2  is a side view of an ink jet chamber of the present invention, situated upon a substrate, showing multiple ink jet chambers with substantially similar chamber volumes and output nozzles;  
         [0012]      FIG. 2   a  is a side view of an ink jet chamber of the present invention, situated upon a substrate, showing multiple ink jet chambers with substantially different chamber volumes and output nozzles;  
         [0013]      FIG. 3  is a side view of an ink jet chamber of the present invention where an internal member provides a plurality of functions;  
         [0014]      FIG. 3   a  is an end view of the ink jet chamber of the present invention taken along line  3   a - 3   a  of  FIG. 3 ;  
         [0015]      FIG. 4  is a side view of an ink jet chamber of the present invention in which a gradient mask creates plurality of geometrically shaped structures;  
         [0016]      FIG. 5  is a side view of an ink jet chamber of the present invention in which a collimated light source creates plurality of geometrically shaped structures; and  
         [0017]      FIG. 5   a  is a side view of an ink jet chamber of the present invention in which an uncollimated light source creates plurality of geometrically shaped structures by exposing through a mask. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0018]     Referring to  FIG. 1 , there is shown a side view of an ink jet chamber assembly  10  situated upon a substrate  20 , which illustrates the creation of vertical structures (hereafter called a chamber wall)  30  by exposing a photo-imageable material  40  through a first mask  50 . First mask  50  is designed to both block and pass the exposing light  60 . The exposing light  60  that is passed by first mask  50  prepares the exposed portion of the photo-imageable material  40  through its entire thickness down to the substrate  20 . This produces an exposed photo-imageable material that becomes the chamber walls  30  horizontally adjacent to the thermal element  70 . The exposing light  60  used for exposing the photo-imageable material  40  through the first mask  50  can be variably adjustable in intensity, dose, and wavelength for the purpose of modifying the resultant structures produced in the photo-imageable material  40 . In regards to wavelengths of the exposing light  60 , those wavelengths can consist of a plurality of conditions including fixed, variable, single, dual, multiple or mixed.  
         [0019]     In the preferred embodiment, for example, the wavelength of the exposing light  60  is at 365 nm corresponding to the I-line of a mercury light source. The exposure is performed with a contact or proximity aligner. Alternatively an I-line stepper can be used.  
         [0020]     A typical photo-imageable material used in this invention is SU-8 2000 Photoresist available from MicroChem Corporation of Newton Massachusetts. SU-8 2000 (formulated in cyclopentanone) is a chemically-amplified, epoxy-based negative resist. Standard formulations are offered to cover a wide range of film thicknesses from &lt;1 μm to &gt;200 μms. The SU-8 2000 resist has a high functionality, high optical transparency and is sensitive to near UV radiation. Images having exceptionally high aspect ratios and straight sidewalls are readily formed in thick films by contact-proximity or projection printing. Cured SU-8 2000 is highly resistant to solvents, acids and bases and has excellent thermal stability, making it well suited for applications in which cured structures are a permanent part of the device.  
         [0021]     Referring now to  FIG. 1   a,  there is illustrated a side view of an ink jet chamber assembly  10 , of the present invention. It is positioned upon a substrate  20 , showing the creation of a horizontal structure (hereafter called a chamber roof)  80  by exposing the photo-imageable material  40  (from  FIG. 1 ) through a second mask  90 . It is apparent to those skilled in the art that the first mask  50  has been discarded and replaced by second mask  90 . Second mask  90  is designed to both block and pass the exposing light  60 . The light that is passed by second mask  90  prepares the photo-imageable material  40  for producing an exposed photo-imageable material  40 , which becomes the chamber roof  80  positioned vertically above and adjacent the thermal element  70 . This second exposure is preferably performed immediately following the first exposure described in  FIG. 1   a.  Alternatively, for robustness, a short baking under heat is performed prior to second exposure. The exposing light  60  used for exposing the photo-imageable material  40  through the second mask  90  can be variably adjustable in intensity, dose, and wavelength for the purpose of modifying the resultant structures produced in the photo-imageable material  40  (from  FIG. 1 ). In regards to wavelengths of the exposing light  60 , those wavelengths can consist of a plurality of conditions including fixed, variable, single, dual, multiple or mixed.  
         [0022]     In a preferred embodiment, the wavelength of the second exposing light  60  is at 365 nm and the process described after the first mask  50  is repeated. In an alternative embodiment, the wavelength of the second exposure light is selected from lower wavelength lines of a mercury light source. For example, lines in the 320 nm wavelength region can be used. The reduced transparency of the photo-imageable material  40  at this lower wavelength allows finer tuning of the chamber roof thickness  80  and also provides less dependence on substrate reflectivity.  
         [0023]     Still referring to  FIG. 1   a,  a shaded area that represents unexposed photo-imageable material  100  remains (formerly  40  at  FIG. 1 ). It will be instructive to note that a semi-finished ink jet chamber exists with both exposed chamber walls  30  and an exposed chamber roof  80 , and that the aforementioned controlled variability of the exposing light  60  is used to control both the height of the chamber walls  30  and the thickness of the chamber roof  80 , as described hereinabove. The lack of any exposure over the thermal element  70  creates by default an ink jet nozzle  110 . At this point, the chamber walls  30  and chamber roof  80  are baked to complete the hardening process for the exposed photo-imageable material  40 , but leaves any unexposed photo-imageable material  100  unaffected and removable. The removal of the unexposed photo-imageable material is accomplished by flushing with a solvent such as cyclopentanone. After flushing is complete, a final cure at a temperature of at most 200 degrees Centigrade finalizes the ink jet chamber assembly  10  drawn in  FIG. 1   b.    
         [0024]     Referring to  FIG. 1   b , there is illustrated a side view of the completed and processed ink jet chamber assembly  10  of the present invention. It is positioned upon a substrate  20 , and shows chamber walls  30  upon which is situated a chamber roof  80  and an ink jet nozzle  110  created by washing out the unexposed photo-imageable material  100  (the process described in the previous paragraph). The ink jet nozzle  110  is shown disposed substantially directly above and adjacent the thermal element  70 , and adjacent to a vertical support member  120 . It is instructive to note that a supply port  160  is subsequently put into the substrate  20  for permitting inks or fluids to pass into the ink jet chamber assembly  10 .  
         [0025]     Referring now to  FIG. 2 , there is shown a side view of a plurality of ink jet chambers  10 . The process as described previously was, for descriptive clarity, described for creating a single ink jet chamber  10 . However, the present invention also provides the ability to produce a plurality of ink jet chamber assemblies  10  upon the same substrate  20 , which greatly enhances the reduced complexity, reduced manufacturing steps and lower costs achieved by the methods described in this invention. Those skilled in the art will readily be able to apply the above teachings to the plurality of ink jet chambers  10 . Additionally, it is instructive to note that  FIG. 2  details a plurality of ink jet chamber assemblies  10  with essentially the same internal structure and volumes with regards to one another.  
         [0026]     Referring next to  FIG. 2   a , there is shown the ink jet chamber assemblies  10  situated on the substrate  20 , and having different internal structure and volumes with respect to one another, such as nozzle dimensions and chamber volumes. This illustrates how the present invention can be modified by using different masks along with different exposures to control the formation of different features in a plurality of ink jet chamber assemblies  10 .  
         [0027]     Referring next to  FIGS. 3 and 3   a , there is illustrated a finished and cured ink jet chamber assembly  10  situated on substrate  20 . A vertical support member  120  is a support for the chamber roof  80 , but it can also be manufactured with an additional function in mind such as filtering an impurity such as dust that may be suspended within a supplied ink or fluid (not shown). This filtering function would be engineered in a manner that integrates the filter as a plurality of posts  135  across the ink jet chamber with predetermined spacing between the posts  135  for the blocking of impurities and drawn in  FIG. 3   a . Supplied inks or fluids (not shown) would be sourced from a reservoir (not shown) through the supply port  160 . Alternatively, posts  135  may be a single integrated wall composed of a porous material for permitting the filtering. Additionally, post  135  may serve as baffles.  
         [0028]     In operate the ink jet chamber, electrical energies applied to the thermal element  70  ejects inks or fluids (not shown) from an ink jet chamber assembly  10  through an ink jet nozzle  110 . The process of ejecting ink creates shock waves within the ink jet chamber assembly  10  that are severe enough to limit the lifetime of the ink jet chamber assembly  10 . Baffles serve the function of dampening the shock waves thus increasing the lifetime of the ink jet chamber assembly  10 .  
         [0029]     Referring now to  FIG. 4 , there is shown an alternative method for producing chamber walls  30  that have a slanted chamber wall  180 . In this case, exposing light  60  passes through a gradient mask  170  for producing the slanted chamber walls.  
         [0030]     Referring next to  FIG. 5 , the same effect can be achieved by using a collimated light source  200  to directly expose the photo-imageable material  40  (referring back to  FIG. 1 ) or using an un-collimated light source  210  through a third mask  190  detailed in  FIG. 5   a.    
         [0031]     The invention has been described with reference to a preferred embodiment. However, it will be appreciated that variations and modifications can be effected by a person of ordinary skill in the art without departing from the scope of the invention.  
       PARTS LIST  
       [0000]    
       
           10  ink jet chamber assembly/assemblies  
           20  substrate  
           30  vertical structures (chamber wall)  
           40  photo-imageable material  
           50  first mask  
           60  exposing light  
           70  thermal element  
           80  horizontal Structure (chamber roof)  
           90  second mask  
           100  unexposed and uncured epoxy photo-imageable material  
           110  ink jet nozzle  
           120  vertical support member  
           135  posts  
           160  supply port  
           170  gradient mask  
           180  slanted chamber wall  
           190  third mask  
           200  collimated light source  
           210  un-collimated light source