Patent Publication Number: US-7909439-B2

Title: Liquid ejecting head and liquid ejecting apparatus

Description:
This application claims priority to Japanese Patent Application No. 2008-075312, filed Mar. 24, 2008, the entire disclosure of which is expressly incorporated by reference herein. 
     BACKGROUND 
     1. Technical Field 
     The present invention relates to a liquid ejecting head and a liquid ejecting apparatus capable of ejecting a liquid, and particularly to an ink jet printing head and an ink jet printing apparatus capable of ejecting ink as the liquid. 
     2. Related Art 
     As an ink jet printing head which is a liquid ejecting head, there is known an ink jet printing head which includes a flow passage forming substrate provided with pressure generating chambers individually communicating with nozzle openings and a communication section communicating with the pressure generating chambers, piezoelectric elements formed on one surface of the flow passage forming substrate, and a reservoir forming substrate provided with a reservoir section joined with the surface of the flow passage forming substrate on which the piezoelectric elements are formed and forming a part of a reservoir together with the communication section. In the ink jet printing head, the flow passage forming substrate and the reservoir forming substrate are adhered to each other through an adhesive layer (for example, see JP-A-2006-082529). 
     However, the ink jet printing head having the above-described configuration has a problem in that crack may occur in an area corresponding to liquid passages of an elastic film formed on the flow passage forming substrate. 
     This problem occurs not only in the ink jet printing head ejecting ink but also in the other liquid ejecting heads ejecting a liquid other than ink. 
     SUMMARY 
     An advantage of some aspects of the invention is that it provides a liquid ejecting head and a liquid ejecting apparatus improving reliability by preventing crack from occurring in an area corresponding to liquid passages of an elastic film. 
     According to an aspect of the invention, there is provided a liquid ejecting head including: a flow passage forming substrate which is provided with a liquid passage having a pressure generating chamber communicating with a nozzle opening for ejecting a liquid and a communication section communicating with the liquid passage; an elastic film which is formed above one surface of the flow passage forming substrate and has an opening in an area opposed to the communication section; a pressure generating unit which applies pressure to the inside of the pressure generating chamber; and a reservoir forming substrate which is adhered onto the flow passage forming substrate above a side of the pressure generating unit and is provided with a reservoir section communicating with the communication section to form a part of a reservoir. An intermediate layer patterned inward from the opening of the elastic film is formed in an area which is the periphery of the communication section on the elastic film and corresponds to the liquid passage, and the flow passage forming substrate and the reservoir forming substrate are adhered to each other through at least the intermediate layer. In addition, an end portion of the intermediate layer on a side of the opening of the elastic film is formed as a tapered portion of which a thickness is gradually smaller, and a cross-section shape in a direction in which the thickness of the tapered portion is gradually smaller is a concavely curved plane. 
     According to the liquid ejecting head, the end portion of the intermediate layer above the side of the opening of the elastic film is formed as the tapered portion of which the thickness is gradually smaller and the cross-section shape in the direction the thickness of the tapered portion is gradually smaller is the concavely curved plane. Therefore, even when the adhesive layer is thermally expanded and stress thus occurs due to occurrence of bubbles in the adhesive layer or mixing of a foreign substance, the stress is not focused on the end portion of the intermediate layer above a side of the elastic film. Accordingly, it is possible to prevent crack from occurring in an area corresponding to the liquid passages of the elastic film. Moreover, it is possible to improve reliability. 
     The liquid ejecting head according to this aspect of the invention may further include a metal layer which is provided to cover at least a part of an upper surface of the intermediate layer and the end portion of the intermediate layer on the side of the opening of the elastic film. A surface of the metal layer in an area corresponding to the tapered portion of the intermediate layer is shaped in a concavely curved plane. With such a configuration, the stress is not focused on the end portion of the intermediate layer on the side of the opening of the elastic film. Accordingly, it is possible to prevent crack from occurring in the area corresponding to the liquid passages of the elastic film. Moreover, it is possible to improve reliability. 
     In the liquid ejecting head according to this aspect of the invention, the pressure generating unit may be a piezoelectric element including a lower electrode, a piezoelectric layer, and an upper electrode, the intermediate layer may be formed of an insulating film, and the metal layer may be a discontinuous metal layer which is formed of the same material as that of a lead electrode drawn from the piezoelectric element and is discontinuous from the lead electrode. With such a configuration, it is possible to prevent crack from occurring in the area corresponding to the liquid passages of the elastic film. 
     According to another aspect of the invention, there is provided a liquid ejecting apparatus including the liquid ejecting head. With such a configuration, by preventing crack from occurring in the area corresponding to the liquid passages of the elastic film, it is possible to provide the liquid ejecting apparatus improved in reliability. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements. 
         FIG. 1  is an exploded perspective view illustrating the overall configuration of a printing head according to a first embodiment. 
         FIGS. 2A and 2B  are a top view and a sectional view illustrating the printing head according to the first embodiment, respectively. 
         FIG. 3  is an expanded sectional view illustrating the vicinity of a reservoir of the printing head according to the first embodiment. 
         FIGS. 4A to 4C  are sectional views illustrating a method of manufacturing the printing head according to the first embodiment. 
         FIGS. 5A to 5C  are sectional views illustrating the method of manufacturing the printing head according to the first embodiment. 
         FIGS. 6A to 6C  are sectional views illustrating the method of manufacturing the printing head according to the first embodiment. 
         FIGS. 7A to 7C  are sectional views illustrating the method of manufacturing the printing head according to the first embodiment. 
         FIG. 8  is a schematic diagram illustrating an example of an ink jet printing apparatus according to an embodiment. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Hereinafter, an embodiment of the invention will be described in detail. 
       FIG. 1  is an exploded perspective view illustrating the overall configuration of an ink jet printing head as an example of a liquid ejecting head according to the embodiment.  FIGS. 2A and 2B  are a top view of  FIG. 1  and a sectional view taken along the line IIB-IIB of  FIG. 2A , respectively.  FIG. 3  is an expanded sectional view illustrating the vicinity of a reservoir. 
     As illustrated in the drawings, in this embodiment, a flow passage forming substrate  10  is formed of a silicon single crystal substrate. In addition, an elastic film  50  formed of silicon dioxide is formed in advance on one surface of the flow passage forming substrate  10 . Pressure generating chambers  12  partitioned by a plurality of partition walls  11  are arranged in parallel in the flow passage forming substrate  10  in the width direction (transverse direction). Ink supply passages  14  and communication passages  15  are partitioned by the partition walls  11  in one ends in a longitudinal direction of the pressure generating chambers  12  of the passage forming substrate  10 . A communication section  13  communicating with the communication passages  15  is formed outside the communication passages  15 . As described in detail, the reservoir forming substrate  30  is joined onto the surface of the flow passage forming substrate  10  on the side of the elastic film  50 . In addition, the communication section  13  communicates with a reservoir section  31  provided in the reservoir forming substrate  30  to form a part of a reservoir  100  which is a common ink chamber of the pressure generating chambers  12 . That is, in this embodiment, the pressure generating chambers  12 , the ink supply passages  14 , the communication passages  15  are provided as liquid passages formed in the flow passage forming substrate  10 . The liquid passages communicate with the communication section  13 . 
     A nozzle plate  20  through which nozzle openings  21  individually communicating with the pressure generating chambers  12  are punched is fixed and adhered to an opening surface of the flow passage forming substrate  10  by an adhesive or a heat welding film. The nozzle plate  20  is formed of glass ceramics, a silicon single crystal substrate, stainless steel, or the like, for example. 
     On the other hand, the elastic film  50  is formed opposite the opening surface of the passage forming substrate  10 , as described above, and an insulating film  55  as an intermediate layer is formed on the elastic film  50 . 
     Piezoelectric elements  300  each including a lower electrode film  60 , a piezoelectric layer  70 , and an upper electrode film  80  are formed on the insulating film  55 . In this embodiment, the lower electrode film  60  serves as a common electrode of the piezoelectric elements  300  and the upper electrode film  80  serves as an individual electrode of each of the piezoelectric elements  300 . However, the reverse configuration is also possible depending on the restriction on a driving circuit or wirings. 
     A lead electrode  90  is drawn from the upper electrode film  80  of each of the piezoelectric elements  300 . Voltage is selectively applied to the piezoelectric element  300  through the lead electrode  90 . In addition, the lead electrode  90  includes an underlying layer  91  made of nickel chrome (NiCr), for example, and a metal layer  92  formed on the underlying layer  91  and made of gold (Au), for example. The underlying layer  91  serves as an underlying layer for closely contacting the metal layer  92  and the insulating film  55  and also serves as a barrier layer for preventing metal forming the upper electrode film  80  and the metal layer  92  from chemically reacting. 
     A discontinuous metal layer  190  formed of the same material layers of the underlying layer  91  and the metal layer  92  included in each of the lead electrodes  90  and formed so as to be discontinuous from the lead electrodes  90  is formed in an area which is the periphery of the communication section  13  on the elastic film  50  and corresponds to the liquid passages. The upper surface of the discontinuous metal layer  190  is covered with the adhesive layer  35  formed of an epoxy-based adhesive, for example. The reservoir forming substrate  30  provided with the reservoir section  31  in the area opposed to the communication section  13  through the adhesive layer  35  is joined to the flow passage forming substrate  10  provided with the piezoelectric elements  300 . By providing the discontinuous metal layer  190  in the area which is the periphery of the communication section  13  on the elastic film  50  and corresponds to the liquid passages, it is possible to prevent an excess adhesive from leaking without causing unevenness of the height of the periphery of the communication section  13  and the height of the lead electrodes  90 , when the flow passage forming substrate  10  and the reservoir forming substrate  30  are adhered to each other. 
     As shown in  FIG. 3 , the elastic film  50  has an opening  52  in an area opposed to the communication section  13 . The insulating film  55  is formed on the elastic film  50  and an opening  56  larger than the opening  52  of the elastic film  50  is formed. That is, the insulating film  55  is patterned more inward than the opening  52  of the elastic film  50 . In the insulating film  55 , the end portion on a side of the opening of the elastic film  50  is formed as a tapered portion of which the thickness is gradually smaller and the cross-section shape in a direction in which the thickness of the tapered portion is gradually smaller is a concavely curved plane. In other words, the cross-section of the opening  56  of the insulating film  55  is formed in the concavely curved plane. 
     The underlying layer  91  of the discontinuous metal layer  190  is formed so as to cover a part of the upper surface of the insulating film  55 , the cross-section of the opening  56  of the insulating film  55 , and the cross-section of the opening  52  of the elastic film  50 . In addition, in the metal layer  92  of the discontinuous metal layer  190 , the end portion on the side of the opening of the elastic film  50  protrudes toward the opening  52  of the elastic film  50  more than the opening  56  of the insulating film  55 . In the underlying layer  91  and the metal layer  92  forming the discontinuous metal layer  190 , surfaces ( 91   a  and  92   a ) of areas corresponding to the tapered portion of the insulating film  55  each have a concavely curved plane. 
     In this way, the insulating film  55  has the tapered portion formed such that the end portion on the side of the opening of the elastic film  50  is gradually narrowed and the cross-section shape in the direction in which the thickness of the tapered portion is gradually smaller is the concavely curved plane. With such a configuration, even when the adhesive layer  35  is thermally expanded and stress thus occurs due to occurrence of bubbles in the adhesive layer  35  or mixing of a foreign substance, the stress is not focused on the end portion on the side of the opening of the insulating film  55 . In a known configuration, since stress occurring from the adhesive layer is easily focused on the end portion on the side of the opening of the insulating film, crack occurs in a portion of the elastic film contacting with the end portion on the side of the opening of the insulating film. In this embodiment, however, since the stress is dispersed in the tapered portion of the insulating film  55 , it is possible to prevent crack from occurring in the area corresponding to the liquid passages of the elastic film  50 . 
     In the reservoir forming substrate  30 , a piezoelectric element preserver  32  ensuring a space so as not to interrupt the movement of the piezoelectric elements  300  is formed in an area opposed to the piezoelectric elements  300 . The piezoelectric element preserver  32  has the space so as not to interrupt the movement of the piezoelectric elements  300 . In addition, the space may be sealed in an airtight manner or not sealed. Only the reservoir section  31  may be configured to serve as a reservoir by partitioning the communication section  13  of the flow passage forming substrate  10  into a plurality of portions in every pressure generating chamber  12 . That is, only the pressure generating chambers  12  and the ink supply passages  14  may be formed in the flow passage forming substrate  10 . It is preferable that the reservoir forming substrate  30  is made of a material such as glass or a ceramic material having the substantially same thermal expansibility as that of the passage forming substrate  10 . 
     Connection wirings  200  having a predetermined pattern are provided on the reservoir forming substrate  30  and a driving circuit  210  for driving the piezoelectric elements  300  is mounted on the connection wirings  200 . The driving circuit  210  can be formed of a circuit substrate or a semiconductor integrated circuit (IC), for example. The driving circuit  210  and the lead electrodes  90  are electrically connected to each other through driving wirings  220  formed of a conductive wire such as a bonding wire. 
     A compliance substrate  40  including a sealing film  41  and a fixing plate  42  is joined onto an area corresponding to the reservoir section  31  of the reservoir forming substrate  30 . The sealing film  41  is made of a material having a low rigidity and a flexible property. One surface of the reservoir section  31  is sealed by the sealing film  41 . The fixing plate  42  is made of a material such as metal having a hard property. Since an area opposed to the reservoir  100  of the fixing plate  42  is an opening  43  completely removed in the thickness direction, one surface of the reservoir  100  is sealed only by the sealing film  41  having a flexible property. 
     In an ink jet printing head I according to this embodiment, ink is supplied from an external ink supply member (not shown), the inside from the reservoir  100  to the nozzle openings  21  is filled with the ink, and ink droplets are ejected from the nozzle openings  21  by applying voltage between the lower electrode film  60  and the upper electrode film  80  corresponding to each of the pressure generating chambers  12  in accordance with a print signal supplied from the driving circuit  210 , deforming the elastic film  50 , the insulating film  55 , the lower electrode film  60 , and the piezoelectric layer  70  so as to be bent, and increasing the pressure of each of the pressure generating chambers  12 . 
     Hereinafter, a method of manufacturing the ink jet printing head will be described with reference to  FIGS. 4A to 4C  to  FIGS. 7A to 7C .  FIGS. 4A to 4C  to  FIGS. 7A to 7C  are sectional views illustrating pressure generating chambers of a flow passage forming substrate wafer in the longitudinal direction. 
     As shown in  FIG. 4A , a flow passage forming substrate wafer  110  as a silicon wafer is first subjected to thermal oxidation in a diffusion furnace of about 1100° C. to form a silicon dioxide film  51  for forming the elastic film  50  on the surface of the flow passage forming substrate wafer  110 . Subsequently, as shown in  FIG. 4B , the insulating film  55  made of zirconium oxide is formed on the elastic film  50  (the silicon dioxide film  51 ). Specifically, after a zirconium (Zr) layer is formed on the elastic film  50  (the silicon dioxide film  51 ) by a sputtering method, for example, the zirconium layer is subjected to thermal oxidation in the diffusion furnace in the range of 500° C. to 1200° C., for example, to form the insulating film  55  made of zirconium oxide (ZrO 2 ). 
     Subsequently, as shown in  FIG. 4C , after the lower electrode film  60  is formed by laminating platinum and iridium, for example, on the insulating film  55 , the lower electrode film  60  is patterned in a predetermined shape. 
     Subsequently, as shown in  FIG. 5A , the piezoelectric layer  70  made of lead zirconate titanate (PZT), for example, and the upper electrode film  80  made of iridium, for example, are formed on the entire surface of the flow passage forming substrate wafer  110 . Subsequently, as shown in  FIG. 5B , the piezoelectric layer  70  and the upper electrode film  80  are patterned in an area opposed to each of the pressure generating chambers  12  to form the piezoelectric element  300 . In addition, a method of forming the piezoelectric layer  70  is not particularly limited. In this embodiment, for example, the piezoelectric element  70  is formed by a so-called sol-gel method made of metal oxide by dissolving and dispersing a metal organic substance with a solvent, by applying and drying a so-called sol to make a gel, and by again baking the gel at a high temperature to obtain the piezoelectric layer  70 . 
     Subsequently, a mask pattern (not shown) is formed, and the insulating film  55  and the elastic film  50  are patterned by ion milling through the mask pattern to form a through-portion for exposing the surface of the flow passage forming substrate wafer  110  by perforating the insulating film  55  and the elastic film  50  in an area where the communication section (not shown) of the flow passage forming substrate wafer  110  is formed, as shown in  FIG. 5C . Specifically, the opening  56  is formed in the insulating film  55  and the opening  52  is formed in the elastic film  50 . At this time, the end portion on the side of the opening of the insulating film  55  is formed as the tapered portion of which thickness is gradually smaller and the cross-section shape in the direction in which the thickness of the tapered portion is gradually smaller becomes the concavely curved plane. That is, the opening surface of the opening  56  of the insulating film  55  is shaped in the concavely curved plane. Specifically, in a process of forming the resist serving as a mask pattern, by allowing the shape of the end portion of the opening of a resist as a defocus to become the concavely curved plane, the shape of the resist is transferred to the insulating film  55  at the time of forming the opening  56  in the insulating film  55  by ion milling to obtain the end portion on the side of the opening of the insulating film  55  having a desired shape. With such a configuration, even when the adhesive layer  35  is thermally expanded and stress thus occurs due to occurrence of bubbles or mixing of a foreign substance in the manufacturing process, the stress is dispersed in the tapered portion of the insulating film  55 . Since the stress is not focused on the end portion on the side of the opening of the insulating film  55 , it is possible to prevent crack from occurring in the area corresponding to the liquid passages of the elastic film  50 . 
     Subsequently, as shown in  FIG. 6A , the lead electrode  90  is formed. Specifically, the metal layer  92  is first formed on the entire surface of the flow passage forming substrate wafer  110  through the underlying layer  91 , and the discontinuous metal layer  190  including the underlying layer  91  and the metal layer  92  is formed. In addition, a mask pattern (not shown) formed of a resist, for example, is formed on the discontinuous metal layer  190 , and the lead electrode  90  is formed by patterning the metal layer  92  and the underlying layer  91  in every piezoelectric element  300  through the mask pattern. At this time, the discontinuous metal layer  190  discontinuous with the lead electrode  90  remains in an area opposed to the through-portion to seal the through-portion by the discontinuous metal layer  190 . In addition, in the discontinuous metal layer  190 , it is preferable that the surface of the area opposed to the tapered portion of the above-described insulating film  55  is shaped in the concavely curved plane. 
     Here, the major material of the metal layer  92  is not particularly limited, as long as the material is a material having a relatively high conductive property. For example, gold (Au), platinum (Pt), aluminum (Al), and copper (Cu) can be used. In this embodiment, gold (Au) is used. The material of the underlying layer  91  is a material ensuring a close contacting property of the metal layer  92 . Specifically, titanium (Ti), titanium-tungsten compound (TiW), nickel (Ni), chrome (Cr), nickel-chrome compound (NiCr), or the like can be used. In this embodiment, titanium-tungsten compound (TiW) is used. 
     Subsequently, as shown in  FIG. 6B , a reservoir forming substrate wafer  130  is adhered to the flow passage forming substrate wafer  110  through the adhesive layer  35 . Specifically, both the flow passage forming substrate  110  and the reservoir forming substrate wafer  130  are adhered by applying an adhesive to the adhering surface of the reservoir forming substrate wafer  130 , and then heating and hardening the adhesive in a state of pressing the reservoir forming substrate wafer  130  against the flow passage forming substrate wafer  110  under predetermined pressure. At this time, when bubbles occur or a foreign substance is mixed in the adhesive layer  35 , stress occurs due to thermal expansion or the like, but the stress is dispersed in the taper portion of the insulating film  55  having the above-described configuration. That is, the stress is not focused on the end portion on the side of the opening of the insulating film  55 . Accordingly, crack does not occur in the area corresponding to the liquid passages of the elastic film. 
     The reservoir section  31 , the piezoelectric element preserver  32 , and the like are formed in advance in the reservoir forming substrate wafer  130 . The above-described connection wirings  200  are formed in advance in the reservoir forming substrate wafer  130 . In addition, the reservoir forming substrate wafer  130  is a silicon wafer having a thickness of about 400 μm, for example. By adhering the reservoir forming substrate wafer  130 , the rigidity of the flow passage forming substrate wafer  110  is considerably improved. 
     Subsequently, as shown in  FIG. 6C , the flow passage forming substrate wafer  110  is formed so as to have a predetermined thickness. In this embodiment, the flow passage forming substrate wafer  110  is processed by grinding and wet etching so as to have the thickness of about 70 μm, for example. Subsequently, as shown in  FIG. 7A , a mask film  54  made of silicon nitride (SiN), for example, is newly formed on the flow passage forming substrate wafer  110  and patterned in a predetermined shape. Subsequently, as shown in  FIG. 7B , the flow passage forming substrate wafer  110  is subjected to anisotropic etching (wet etching) through the mask film  54  to form the liquid passages (the pressure generating chambers  12 , the ink supply passages  14 , and the communication passages  15  in this embodiment), the communication section  13 , and the like in the flow passage forming substrate wafer  110 . Specifically, the flow passage forming substrate wafer  110  is etched by an etching solution such as a potassium hydroxide water solution until the elastic film  50  and the underlying layer  91  are exposed, in order to simultaneously form the pressure generating chambers  12 , the communication section  13 , the ink supply passage  14 , and the communication passage  15 . 
     When the communication section  13  and the like are formed in this manner, the opening is sealed the discontinuous metal layer  190  including the underlying layer  91  and the metal layer  92 . Accordingly, the etching solution does not flow to a side of the reservoir forming substrate wafer  130  through the opening. With such a configuration, the etching solution is not attached to the connection wirings  200  formed on the surface of the reservoir forming substrate wafer  130  and a defect such as line disconnection can be prevented from occurring. Moreover, a problem with etching of the reservoir forming substrate wafer  130  caused when the etching solution penetrates into the inside of the reservoir section  31  does not occur. 
     When the pressure generating chambers  12  and the like are formed, the surface of the reservoir forming substrate wafer  130  opposite the flow passage forming substrate wafer  110  may be again sealed with a sealing film made of a material such as PPS (polyphenylene sulfide) or PPTA (polyphenylene terephthalamide) having an alkali resistant property. With such a configuration, a defect such as line disconnection of the wirings formed on the surface of the reservoir forming substrate wafer  130  can be more reliably prevented from occurring. 
     Subsequently, as shown in  FIG. 7C , a part of the discontinuous metal layer  190  inside the opening is removed from a side of the communication section  13  by etching. That is, the underlying layer  91  and the metal layer  92  exposed to the side of the communication section  13  is removed by wet etching or the like. 
     Subsequently, the driving circuit  210  is mounted on the connection wirings  200  formed in the reservoir forming substrate wafer  130  and the driving circuit  210  and the lead electrodes  90  are connected to each other through the driving wirings  220  (see  FIGS. 2A and 2B ). Subsequently, unnecessary portions of the outer circumferences of the flow passage forming substrate wafer  110  and the reservoir forming substrate wafer  130  are removed by cutting such as dicing. Subsequently, the nozzle plate  20  provided with the nozzle openings  21  punched therein is joined to the surface of the flow passage forming substrate wafer  110  opposite the reservoir forming substrate wafer  130 . The compliance substrate  40  is joined to the reservoir forming substrate wafer  130 . Then, the ink jet printing head having the above-described configuration is manufactured by dividing the flow passage forming substrate wafer  110  and the like into the flow passage forming substrates  10  and the like having one chip size, as in  FIG. 1 . 
     As described above, the liquid ejecting head according to this embodiment is provided with the insulating film  55  patterned inward from the opening of the elastic film  50  in the adhered area on the liquid passages of the periphery of the communication section  13  on the elastic film  50 . The end portion on the side of the insulating film  55  on the side of the opening of the elastic film  50  is formed as the tapered portion of which the thickness is gradually smaller. The cross-section shape in the direction in which the thickness of the tapered portion is gradually smaller is the concavely curved plane. With such a configuration, even when the adhesive layer  35  is thermally expanded and stress thus occurs due to occurrence of bubbles in the adhesive layer  35  or mixing of a foreign substance, the stress is not focused on the end portion on the side of the communication section  13  of the insulating film  55 . Accordingly, it is possible to prevent crack from occurring in the elastic film  50  on the flow passage forming substrate  10 . 
     Accordingly, the liquid ejecting head according to this embodiment is considerably improved in durability and reliability. 
     OTHER EMBODIMENTS 
     The embodiment of the invention has been described, but the invention is not limited to the above-described embodiment in the basic configuration. In this embodiment, the insulating film  55  serves as the intermediate layer, but the invention is not limited thereto. The intermediate layer is formed in the adhered area of the reservoir forming substrate  30  on the liquid passages in the periphery of the communication section  13  on the elastic film  50 . For example, the insulating film  55  and the lower electrode film  60  may serve as the intermediate layer. When the intermediate layer is formed by the insulating film  55  and the lower electrode film  60 , the end portion of the lower electrode film  60  on a side of the opening of the elastic film  50  is formed as the tapered portion of which the thickness is gradually smaller and the cross-section shape in the direction in which the thickness of the tapered portion is gradually smaller is the concavely curved plane. 
     In the above-described embodiment, the metal layer is formed of the discontinuous metal layer  190  discontinuous from the lead electrode  90 . However, the metal layer may be made of a material different from that of the lead electrode  90  or may not be necessarily formed. 
     In the above-described embodiment, the intermediate layer (the insulating film  55 ) and the metal layer (the discontinuous metal layer  190 ) are formed in the periphery of the communication section  13  on the elastic film  50 . However, in only the intermediate layer (and the metal layer) formed in the periphery of the communication section  13  and the area corresponding to the liquid passages, the end portion of the intermediate layer on the side of the opening of the elastic film is formed as the tapered portion of which the thickness is gradually smaller and the cross-section shape in the direction in which the thickness of the tapered portion is gradually smaller is the concavely curved plane. Of course, in the intermediate layer formed in an area where the liquid passages are not formed, the end portion on the side the opening may be also shaped in the concavely curved plane. 
     The above-described ink jet printing head forms a part of a printing head unit having an ink passage communicating with an ink cartridge and the like and is mounted on an ink jet printing apparatus.  FIG. 8  is a schematic diagram illustrating an example of the ink jet printing apparatus. 
     As shown in  FIG. 8 , an ink jet printing apparatus II includes printing head units  1 A and  1 B which each have an ink jet printing head I. The printing head units  1 A and  1 B are provided such that cartridges  2 A and  2 B forming an ink supply unit are detachably mounted. A carriage  3  mounted with the printing head units  1 A and  1 B is provided to freely move along a carriage shaft  5  attached to an apparatus main body  4  in a shaft direction. The printing head units  1 A and  1 B are each configured to eject black ink and color ink, for example. 
     The carriage  3  mounting the printing head units  1 A and  1 B is moved along the carriage shaft  5  by delivering a driving force of a driving motor  6  to the carriage  3  through a plurality of toothed-gears (not shown) and a timing belt  7 . On the other hand, a platen  8  is formed along the carriage shaft  5  in the apparatus main body  4 . In addition, a printing sheet S as a printing medium such as a paper sheet fed by a sheet feeding roller or the like (not shown) is wound by the platen  8  so as to be transported. 
     In the above-described embodiment, the ink jet printing head I has been described as an example of the liquid ejecting head. However, the invention is devised so as to be applied to various liquid ejecting heads. Of course, the invention is applicable to a method of manufacturing the liquid ejecting head for ejecting a liquid other than ink. Examples of the liquid ejecting head include various printing heads used for an image printing apparatus such as a printer, a color material ejecting head used to manufacture a color filter such as a liquid crystal display, an electrode material ejecting head used to form electrodes such as an organic EL display or an FED (Field Emission Display), and a bio organism ejecting head used to manufacture a bio chip.