Patent Publication Number: US-6988316-B1

Title: Process for manufacturing a fluid jetting apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of Korean Application No. 98-54149, filed Dec. 10, 1998, in the Korean Patent Office, the disclosure of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a process for manufacturing a fluid jetting apparatus, and more particularly, to a process for manufacturing a fluid jetting apparatus of a print head employed in output apparatuses such as an ink jet printer, a facsimile machine, etc., to jet fluid through a nozzle. 
     2. Description of the Related Art 
     A print head is a part or a set of parts which are capable of converting output data into a visible form on a predetermined medium using a type of printer. Generally, such a print head used for an ink jet printer, and the like, uses a fluid jetting apparatus which is capable of jetting a predetermined amount of fluid through a nozzle to an exterior of a fluid chamber holding the fluid by applying a physical force to the fluid chamber. 
     According to methods for applying a physical force to the fluid within the fluid chamber, a fluid jetting apparatus is roughly grouped into a piezoelectric system and a thermal system. The piezoelectric system pushes out ink within the fluid chamber through a nozzle through an operation of a piezoelectric element which is mechanically expanded in accordance with a driving signal. The thermal system pushes the fluid through the nozzle by means of bubbles which are produced out of the fluid within the fluid chamber by the heat generated by an exothermic body. Recently, also, a thermal compression system has been developed, which is an improved form of the thermal system. The thermal compression system jets the fluid by driving a membrane by instantly heating a vaporizing fluid which acts as working fluid. 
       FIG. 1  is a vertical sectional view of a fluid jetting apparatus according to a conventional thermal compression system. A fluid jetting apparatus of the thermal compression system includes a heat driving part  10 , a membrane  20 , and a nozzle part  30 . 
     A substrate  11  of the heat driving part  10  supports the heat driving part  10  and the whole structure that will be constructed later. An insulated layer  12  is defused on the substrate  11 . An electrode  14  is a conductive material for supplying an electric power to the heat driving part  10 . An exothermic body  13  is a resistive material having a predetermined resistance for expanding a working fluid by converting electrical energy into thermal energy. Working fluid chambers  16  and  17  contain the working fluid, to maintain the pressure of the working fluid which is expanded by heat, are connected by a working fluid introducing passage  18 , and are formed with a working fluid barrier layer  15 . 
     Further, the membrane  20  is a thin diaphragm which is adhered to an upper portion of the working fluid barrier layer  15  and the working fluid chambers  16  and  17  are moved upward and downward by the pressure of the expanded working fluid. The membrane  20  includes a polyimide coated layer  21  and a polyimide adhered layer  22 . 
     Jetting fluid chambers  37  and  38  are chambers, formed to enclose the jetting fluid, which are designed to jet the fluid only through a nozzle  35  formed in the nozzle plate  34  when the pressure transmitted through the membrane  20  is applied to the jetting fluid. The jetting fluid is the fluid which is pushed out of the jetting fluid chambers  37  and  38  in response to the driving of the membrane  20 , and finally jetted to the exterior. A jetting fluid introducing passage  39  connects the jetting fluid chambers  37  and  38 . The jetting fluid chambers  37  and  38  and the jetting fluid introducing passage  39  are formed in a jetting fluid barrier layer  36 . The nozzle  35  is an orifice through which the jetting fluid which is held using the membrane  20  and the jetting fluid chambers  37  and  38  is emitted to the exterior. Another substrate  31  of the nozzle part  30  is temporarily employed for constructing the nozzle part  30 , and the substrate  31  of the nozzle part  30  should be removed before the nozzle part  30  is assembled. 
     A process for manufacturing the fluid jetting apparatus according to the conventional thermal compression system will be described below. 
       FIG. 2  shows a process for manufacturing a fluid jetting apparatus according to a conventional roll method. 
     As shown in  FIG. 2 , a nozzle plate  34  is transferred from a feeding reel  51  to a take-up reel  52 . In the process of transferring the nozzle plate  34  from the feeding reel  51  to the take-up reel  52 , a nozzle is formed on the nozzle plate  34  by laser processing equipment  53 . After the nozzle is formed, air is jetted from an air blower  54  so as to eliminate extraneous substances attached to the nozzle plate  34 . Next, an actuator chip  40  is bonded with the nozzle plate  34  by a tab bonder  55 , and accordingly, the fluid jetting apparatus is completed. The completed fluid jetting apparatuses are wound around the take-up reel  52  to be preserved, and then sectioned in pieces in the manufacturing process for the print head. Accordingly, each piece of the fluid jetting apparatuses is supplied into the manufacturing line of a printer. 
       FIGS. 3A and 3B  are views for showing a process for manufacturing the heat driving part and  FIG. 3C  is a view for showing a process for manufacturing the membrane on the heat driving part of the conventional fluid jetting apparatus.  FIGS. 4A  to  4 C are views for showing a process for manufacturing the nozzle part. 
     In order to manufacture the conventional fluid jetting apparatus, the heat driving part  10  and the nozzle part  30  should be manufactured separately. Here, the heat driving part  10  is completed as the separately-made membrane  20  is adhered to the working fluid barrier layer  15  of the heat driving part  10 . After that, by reversing and adhering the separately-made nozzle part  30  to the membrane  20 , the fluid jetting apparatus is completed. 
       FIG. 3A  shows a process for diffusing the insulated layer  12  on the substrate  11  of the heat driving part  10 , and for forming the exothermic body  13  and the electrode  14  on the insulated layer  12  in turn. Referring to  FIG. 3B , the working fluid chambers  16  and  17  and the working fluid introducing passage  18  are formed by an etching process of the working fluid barrier layer  15  through a predetermined mask patterning. More specifically, the heat driving part  10  is formed as the insulated layer  12 , the exothermic body  13 , the electrode  14 , and the working fluid barrier layer  15  are sequentially laminated on the substrate  11  (which is a silicon-substrate). The working fluid chambers  16  and  17  which are filled with the working fluid to be expanded by heat, are formed on the etched portion of the working fluid barrier layer  15 . The working fluid is introduced through the working fluid introducing passage  18 . 
       FIG. 3C  shows the separately-made membrane  20  being adhered to the upper portion of the completed heat driving part  10 . The membrane  20  is a thin diaphragm, which is to be driven in a direction of the jetting fluid chamber  37  (see  FIG. 1 ) by the working fluid which is heated by the exothermic body  13 . 
       FIG. 4A  shows a process for forming the nozzle  35  by the laser processing equipment  53  after an insulated layer  32  and the nozzle plate  34  are sequentially formed on a substrate  31  of the nozzle part  30 .  FIG. 4B  shows a process for forming a jetting fluid barrier layer  36  on the upper portion of the construction shown in  FIG. 4A , and then for forming the jetting fluid chambers  37  and  38  and the fluid introducing passage  39  (see  FIG. 1 ) by an etching process through a predetermined mask patterning.  FIG. 4C  shows a process for exclusively removing the nozzle plate  34  from the conductive layer  32  and the substrate  31  of the nozzle part  30 . The nozzle part  30  includes the jetting fluid barrier layer  36  and the nozzle plate  34 . On the etched portion of the jetting fluid barrier layer  36 , the jetting fluid chambers  37  and  38  which are filled with the fluid to be jetted and the fluid introducing passage  39 , are formed. The jetting fluid such as an ink, or the like, is introduced through the jetting fluid introducing passage  39  (see FIG.  1 ). The nozzle  35  is formed on the nozzle plate  34  to be interconnected with the jetting fluid chamber  37 , so that the fluid is jetted out through the nozzle  35 . The nozzle part  30  is manufactured by the processes that are shown in  FIGS. 4A  to  4 C. First, the nozzle plate  34  inclusive of the nozzle  35 , is formed on the substrate  31  having the insulated layer  32  through an electroplating. Next, the jetting fluid barrier layer  36  is laminated thereon, and the jetting fluid chambers  37  and  38  and the jetting fluid introducing passage  39  are formed through a lithographic process. Finally, as the insulated layer  32  and the substrate  31  are removed, the nozzle part  30  is completed. The completed nozzle part  30  is reversed, and then adhered to the membrane  20  which has been pre-assembled with the heat driving part  10 . More specifically, the jetting fluid barrier layer  36  of the nozzle part  30  is adhered to the polyimide coated layer  21  of the membrane  20 . 
     The operation of the fluid jetting apparatus according to the thermal compression system will be described below with reference to the construction shown in FIG.  1 . 
     First, an electric power is supplied through the electrode  14 , and an electric current flows through the exothermic body  13  which is connected to the electrode  14 . In such a situation, the exothermic body  13  generates a heat due to its resistance. The fluid within the working fluid chamber  16  is subjected to a resistance heating, so that the fluid starts to vaporize when the temperature thereof exceeds a predetermined temperature. As the fluid vaporizes more and more due to the heat, the vapor pressure accordingly increases. As a result, the membrane  20  is driven upward. More specifically, as the working fluid undergoes thermal expansion, the membrane  20  is pushed upward toward the direction indicated by the arrow in FIG.  1 . As the membrane  20  is pushed upward, the fluid within the jetting fluid chamber  37  is jetted to the exterior through the nozzle  35 . 
     Then, when the supply of electric power is stopped, the heat from the exothermic body  13  is no longer generated. Accordingly, the fluid within the working fluid chamber  16  is cooled to a liquid state, so that the volume thereof decreases and the membrane  20  recovers its original shape. 
     Meanwhile, a conventional material of the nozzle plate  34  is mainly made of nickel, but the trend in using a polyimide synthetic resin has increased recently. When the nozzle plate  34  is made of the polyimide synthetic resin, it is fed by a reel type. The fluid jetting apparatus is completed by the way in which a chip is bonded on the nozzle plate  34  fed in the reel type. 
     With the conventional fluid jetting apparatus, however, since the nozzle plate and the jetting fluid barrier layer should be separately formed during the manufacturing process of the nozzle part, numerous complex processes are required. As a result, the productivity thereof is decreased. Further, if the conventional electroplating method is employed, pressures are not uniformly exerted over the whole area of the substrate due to the uneven thickness, and also due to the technical problems in forming the jetting fluid chambers. Also, according to the conventional system, since the heat driving part-membrane assemblies, and the nozzle parts have to be sectioned in pieces into the respective units to be attached to each other, productivity decreases and the reliability deteriorates. 
     SUMMARY OF THE INVENTION 
     The present invention has been made to overcome the above-described problems of the related art, and accordingly, it is an object of the present invention to provide a process for manufacturing a fluid jetting apparatus in which, during the manufacturing process of a nozzle part, a nozzle is integrally formed with jetting fluid chambers on one substrate to be adhered to a heat driving part-membrane assembly on another substrate, and then the final assembly thereof is sectioned in pieces into complete fluid jetting apparatuses. 
     Additional objects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention. 
     In order to accomplish the above and other objects of the present invention, a method of manufacturing a fluid jetting apparatus according the present invention includes (A) forming a heat driving part, a membrane, and a nozzle part; and (B) forming a nozzle and jetting fluid chambers sequentially by using one nozzle plate, and assembling the heat driving part, the membrane, and the nozzle part, sequentially. 
     The step (B) includes (1) laminating the nozzle plate on a substrate; (2) forming the nozzle on the nozzle plate; (3) forming the jetting fluid chambers by extending the nozzle in a depth direction, and (4) separating the nozzle plate from the substrate. 
     It is preferable that the nozzle plate is adhered to the substrate, and the nozzle plate is abraded to have a predetermined thickness before the step (2). 
     It is also preferable that the nozzle plate is abraded to have a predetermined thickness by a chemo-mechanical polishing, and the nozzle plate is made of silicon. 
     It is further preferable that the steps (2) and (3) are carried out through a lithography, respectively, and the step (3) is carried out through an anisotropic etching of the lithography. 
     Here, it is preferable that the step (4) is executed after the step of sequentially assembling the heat driving part, the membrane, and the nozzle part. 
     In order to accomplish the above and other objects of the present invention, a process for manufacturing a fluid jetting apparatus includes (A) forming a heat driving part, a membrane, and a nozzle part; and (B) assembling the heat driving part, the membrane, the nozzle part, sequentially, the step (B) including: (1) laminating a nozzle plate of silicon on a substrate; (2) abrading the nozzle plate to have a predetermined thickness by a chemo-mechanical polishing; (3) forming a nozzle in the nozzle plate through a lithography; (4) forming a jetting fluid chamber on an area where the nozzle is formed by an anisotropic etching of the lithography; and (5) separating the substrate from the nozzle plate. 
     As a result, since the nozzle and the jetting fluid chambers are integrally formed on one substrate of a silicon diaphragm, fewer processes are required. Further, since a flatness of the substrate is excellent, the heat driving part-membrane assembly on one substrate may be assembled with the nozzle part on another substrate. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above objects and advantages will become more apparent and more readily appreciated by describing the preferred embodiment in greater detail with reference to the accompanying drawings, in which: 
         FIG. 1  is a vertical sectional view showing a construction of a fluid jetting apparatus according to a conventional thermal compression system; 
         FIG. 2  is a view showing a process for manufacturing a fluid jetting apparatus according to a conventional roll method; 
         FIGS. 3A and 3B  are views showing a process for manufacturing a heat driving part and  FIG. 3C  is a view drawing a process for manufacturing a membrane on the heat driving part of the conventional fluid jetting apparatus; 
         FIGS. 4A  to  4 C are views showing a process for manufacturing a nozzle part of the fluid jetting apparatus according to the conventional thermal compression system; 
         FIG. 5  is a vertical sectional view of a fluid jetting apparatus according to an embodiment of the present invention; 
         FIGS. 6A and 6B  are views showing a process for manufacturing a heat driving part and  FIG. 6C  is a view showing a processing for manufacturing a membrane on the beat driving part of the fluid jetting apparatus according to the embodiment of the present invention; and 
         FIGS. 7A  to  7 D are views showing a process for manufacturing a nozzle part of the fluid jetting apparatus according to the embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Reference will now made in detail to the present preferred embodiment of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiment is described below in order to explain the present invention by referring to the figures. 
       FIG. 5  is a vertical sectional view of a fluid jetting apparatus according to an embodiment of the present invention. Here, a reference numeral  110  is a heat driving part,  120  is a membrane, and  130  is a nozzle part. 
     The process for manufacturing the fluid jetting apparatus according to an embodiment of the present invention includes the processes of forming the heat driving part  110 , forming the membrane  120 , forming the nozzle part  130 , and sequentially assembling the heat driving part  110 , the membrane  120 , and the nozzle part  130 . 
     With respect to the heat driving part  110 , reference numerals  116  and  117  refer to working fluid chambers, respectively,  114  is an electrode, and  113  is an exothermic body. 
     Further, the reference numeral  112  is an insulated layer,  111  is a substrate,  115  is a working fluid barrier layer, and  118  is a working fluid passage. 
     With respect to the membrane  120 , the reference numeral  121  is a polyimide coated layer, and  122  is a polyimide adhered layer. 
     With respect to the nozzle part  130 , the reference numeral  134  is a nozzle plate,  135  is a nozzle,  136  is a jetting fluid barrier layer, and  137  and  138  are jetting fluid chambers. 
     As shown in  FIG. 5 , a wafer substrate  111  is used for a plurality of the heat driving parts  110 , a plurality of the membranes  120  are adhered to the heat driving parts  110 , the separately-made nozzle parts  130  are integrally adhered to the membranes  120 , and finally, the final assembly thereof is sectioned in pieces into complete fluid jetting apparatuses. 
       FIGS. 6A and 6B  are views for showing a process for manufacturing the heat driving part  110  and  FIG. 6C  is a view for showing a process for manufacturing a membrane  120  of the fluid jetting apparatus according to the present invention, and  FIGS. 7A  to  7 D are views for showing the manufacturing process for the nozzle part  130  of the fluid jetting apparatus according to the embodiment of the present invention. 
     Here, the processes for forming the heat driving part  110  and the membrane  120  may be carried out through the conventional method. Accordingly, the description thereof will be briefly described below with reference to  FIGS. 6A  to  6 C, and then the main aspect of the present invention, i.e., the process of forming the nozzle part  130 , will be described in greater detail with reference to  FIGS. 7A  to  7 D. 
     First, as shown in  FIG. 6A , metal layers are formed on the substrate  111  which has an insulated layer  112  formed thereon. Initially, a first metal layer is formed on the insulated layer  112 , and then the exothermic body  113  is formed by an etching process. After that, another metal layer is formed on the exothermic body  113 , then the electrode  114  is formed by an etching process. Next, as shown in  FIG. 6B , a working fluid barrier layer or a working fluid diaphragm  115  is formed on the upper portion of the construction shown in  FIG. 6A , and then working fluid chambers  116  and  117  and a working fluid passage  118  are formed through the etching process. As a result, the heat driving part  110  is formed. Additionally, a membrane  120 , inclusive of a polyimide coated layer  121  and a polyimide adhered layer  122 , which is formed on another substrate (not shown), is adhered to the working fluid barrier layer  115 . Here, the membrane  120  may be formed on the another substrate and then adhered to the working fluid barrier layer  115 , or the membrane  120  may be directly formed on the working fluid barrier layer  115  via a sacrificial layer, or the like. 
     Meanwhile, the nozzle part  130  is formed on still another substrate. More specifically, as shown in  FIG. 7A , a nozzle plate  134  of a silicon material is laminated on a substrate  131  with an insulated layer  132  by an adhesive or through an anodic-bonding process. Then, the nozzle plate  134  is abraded to have a predetermined thickness that is suitable for forming a nozzle  135  and jetting fluid chambers  137  and  138  and the jetting fluid barrier  136  and a jetting fluid barrier  136  (which are shown in FIG.  7 C), through a chemo-mechanical polishing process. Then, as shown in  FIG. 7B , the nozzle  135  is formed on a pre-determined area on the nozzle plate  134 , through the lithographic process. 
     Next, as shown in  FIG. 7C , the nozzle plate  134  further undergoes the lithographic process, so that the jetting fluid chambers  137  and  138  are formed. In this situation, it is preferable that the etching process of the lithography is carried out by anisotropic etching which has a vertical orientation with respect to the nozzle plate  134 . Accordingly, at the same time the surface of the nozzle plate  134  is etched to a uniform depth in a vertical direction, an area where the nozzle  135  has already been formed is more deeply etched than other areas. As a result, the nozzle  135  is formed at a desired position.  FIG. 7C  shows the jetting fluid chambers  137  and  138  and the jetting fluid barrier  136  and the jetting fluid passage therebetween extending further in a vertical direction by the etching process. 
     Meanwhile, with respect to the lithographic process to form the nozzle  135  and the jetting fluid chambers  137  and  138  and the jetting fluid barrier  136 , the etching process may be a wet etching, or may be a dry etching, such as a reactive ion etching, or the like. 
     Thus, as shown in  FIGS. 7A and 7B , the nozzle is pre-formed by etching the nozzle plate  134  (the result being shown in FIG.  7 B). After this, the nozzle plate  134  is re-etched at the pre-etched state (FIG.  7 B), then the nozzle  135 , the jetting fluid barrier  136 , and the jetting fluid chambers  137  and  138  are formed. 
     Next, as shown in  FIG. 7D , the nozzle part  130  which is now formed with the nozzle  135  and jetting fluid chambers  137  and  138  and the jetting fluid barrier  136 , is reversed and assembled with the upper portion of the membrane-heat driving part assembly, i.e., to the membrane  120  of the membrane-heat driving part assembly. An adhesive, or anodic bonding are employed for this assembling process, and here, the respective structures are assembled while being on their respective substrates. Finally, as the substrate  131  and insulated layer  132  are separated from the nozzle part  130 , the structure of the fluid jetting apparatuses is completed. Here, the substrate  131  may be separated from the nozzle part  130  before adhering the nozzle part-membrane assembly to the heat driving part  110 . Taking into account the property of the assembly work, however, it is more preferable that the substrate  131  is separated from the nozzle part  130  after the completion of the assembly process. After that, the final assembly of the completed fluid jetting apparatuses is sawed into individual fluid jetting apparatuses. The individual fluid jetting apparatuses are then transferred for a process of manufacturing print heads. 
     As described above, according to the present invention, since the nozzle  135  is formed on a single silicon diaphragm together with the fluid jetting chambers  137  and  138 , productivity is increased in comparison with the conventional manufacturing method in which the sectioned nozzle  135  and the fluid jetting chambers  137  and  138  are separately made and assembled with each other. Further, by employing a single diaphragm, the thickness difference on the whole substrate is minimized. As a result, the membrane-heat driving part assembly and nozzle part are enabled to be assembled while being on their own substrates, so that productivity and reliability are greatly increased. According to the present invention, multiple fluid jetting apparatuses are manufactured by bonding a plurality of the heat driving parts  110 , on which a plurality of membranes  120  (FIG.  6 C), with a plurality of nozzle parts (elements  134  and  136 ) ( FIG. 7C ) are formed under the same conditions. Therefore, the thickness of the fluid jetting apparatus formed on one substrate  111  is almost always uniform. 
     While the present invention has been particularly shown and described with reference to the preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be effected therein without departing from the spirit and scope of the invention as defined by the appended claims.