JP2007296706A - Inkjet recording head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact and high-performance inkjet heater board configuration. <P>SOLUTION: Penetration electrodes 610 and 620 of a metal such as Cu, Al or Au which is a material of a greatly good thermal conductivity are formed immediately below or near a heater. Heat generated at an electrothermal converting element 300 is directly radiated to a base material 100 via the penetration electrodes 610 and 620, whereby thermal storage of a substrate can be made minimum. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is applied to an ink jet recording technique, particularly an ink jet recording head that requires high definition and high speed.

  In recent years, inkjet recording technology has rapidly spread along with colorization and personalization of printing technology, and is now becoming a standard in offices and homes as well as electrophotographic technology.

  In addition, the quality of printing has been rapidly improved by making the droplets smaller and various image processing technologies, and now the quality that surpasses silver halide photography has come to be obtained.

As another conventional example, Patent Document 1 can be cited.
JP 2003-072079 A

  However, in the thermal ink jet recording method that utilizes the phase change of the ink liquid that is currently the mainstream in the ink jet recording method, there are various types due to the heat for changing the phase and the temperature change of the recording unit portion of the ink and recording head An adverse effect occurred.

  That is, the main issues include the following.

  1. The heat generated from the electrothermal conversion element is mainly stored in the substrate and the temperature of the substrate changes, so that the characteristics of the ink droplets to be discharged change, and the print quality is greatly affected.

  2. Conventionally, a resistor which is an electrothermal conversion element and an electrode for energizing the resistor are formed on the same plane. Further, in order to reduce the electrical resistance, the electrode generally uses AL in consideration of cost and the like. Further, in order to reduce the wiring resistance, the thickness is generally about 0.2 μm at the minimum, and when it is thick, it is generally formed about 0.6 to 1 μm. However, since it has such a thickness, the AL wiring portion has a thickness difference as described above, and the protective film to be coated on the wiring may not be able to completely cover the AL wiring.

  3. Furthermore, in the case of a generally used protective film of a thin film, particles are present with a certain probability for reasons of the manufacturing process. These particles remarkably deteriorate the covering property of the protective film. However, when the particles are present in the stepped portion of the above-described AL, the covering property is remarkably deteriorated, and when a pinhole is generated, the ink liquid is used. Causes corrosion of AL.

  4). In the case of the thin film wiring using the AL wiring, it is extremely difficult to reduce the wiring resistance because the thickness of the thin film wiring is limited in the process. The power consumption due to the wiring resistance is usually 10% to 30% or more, and is not only consumed as wasted power, but also has a great adverse effect on the characteristics of ink jet recording due to the temperature rise.

  5. Furthermore, in the current ink jet recording head, the heat generated by the resistor is generally dissipated from the substrate to the substrate to which the substrate is bonded via the organic adhesive bonding the substrate. However, in the case of the above configuration, first, since heat is diffused to the substrate itself, the temperature of the substrate is increased, the temperature of the resistor formed on the substrate is increased, and the characteristics as the electrothermal conversion element are changed. There was an effect. In addition, the organic adhesive has a very poor thermal conductivity, and has been a cause of heat storage on the substrate. That is, it is very important how the heat generated by the resistor is radiated to the base material without affecting the other.

  6). In addition, in order to achieve high image quality in recent ink jet recording apparatuses, it is necessary to eject minute ink droplets. To that end, the ink flow path that leads ink to the electrothermal conversion element has been miniaturized. It is essential. However, since the liquid resistance of the ink flow path increases with miniaturization, there has been a serious problem that sufficient fluid characteristics cannot be obtained. In order to solve this problem, it is necessary to form the ink flow path between the electrothermal conversion element and the ink supply port in the shortest time. However, it was difficult to reduce the distance from the vapor ink flow path.

  FIG. 4 is a diagram showing a conventional example.

  The present invention has found a solution to the above problems.

  Means and actions for solving the present invention are as follows.

  1. By forming a through electrode of a metal such as Cu, Al, or Au, which is an extremely good heat conductive material, directly under or in the vicinity of the heater, the heat generated by the electrothermal conversion element is directly applied to the substrate through the through electrode. By dissipating heat, it is possible to minimize the heat storage of the substrate.

  2. Conventionally, a conductive electrode formed on the same surface as the electrothermal conversion element can be used as a penetrating electrode and conducted to a surface facing the electrothermal conversion element formation surface, thereby greatly reducing the planar area. An extremely large cost reduction is possible.

  3. As described in item 2 above, the conductive electrode can be eliminated or formed to a minimum, so that the reliability of the electrode, which has conventionally been a problem around the electrothermal transducer, is dramatically improved. It becomes possible. Specifically, although the conductive electrode is generally formed of AL, since AL does not have corrosion resistance to the ink liquid, the protective film of the electrode has defects such as cracks and pinholes even at one location. In such a case, the wiring electrodes corrode very quickly and can no longer be used. Therefore, improving the reliability of the wiring electrode is very effective for improving the reliability of the inkjet head.

  4). The wiring electrode described in item 3 above is usually designed to be as thick as possible in order to reduce its electrical resistance. However, when the wiring electrode is made thicker, a step is generated at the end of the wiring, and there is a possibility that the above-described reliability may be hindered in a portion where the protective film has poor coverage. According to the present invention, it is possible to reduce the resistance of the wiring electrode without causing the step portion.

  5. By forming the wiring electrode described so far on the surface facing the electrothermal conversion element, there is no wiring in the vicinity of the electrothermal conversion element, and the ink supply port can be formed in the immediate vicinity of the electrothermal conversion element. It was. Therefore, the flow resistance of the ink flow path can be kept extremely low, and a low resistance ink flow path that cannot be achieved by a conventional inkjet head is made possible.

  A low-resistance ink flow path that cannot be achieved by a conventional inkjet head is made possible.

  Next, details of the present invention will be described in accordance with the description of the embodiments.

  A first embodiment of the present invention is shown in FIG.

  FIG. 1a shows a top view, a cross-sectional view, and a bottom view of the present invention.

  FIG. 1b shows a cross-sectional view including the ink flow path and the discharge port.

  In order to electrically connect the insulating film, the electrothermal conversion element 300, the protective film 400, the through electrodes 610 and 620, the through holes 800 and 810 for supplying ink, and the electrothermal conversion element 300 and the through electrodes 610 and 620 on the substrate 100 Via holes 210 and 220 are formed.

  In addition, an orifice is formed on the electrothermal conversion element 300 so as to communicate with the through holes 800 and 810 and form an ink supply path and a discharge port for teaching ink to a discharger.

  Here, the base material 100 can be either a semiconductor substrate such as Si or an insulating substrate such as alumina. However, in the semiconductor substrate, the through electrodes 610 and 620 and the base material 100 are electrically insulated. The insulating layer 200 is essential between the through electrodes 610 and 620 and the substrate 100.

  There are methods such as dry etching with corrosive gas, wet etching with corrosive liquid, or laser method by laser ablation to form through electrodes 610,620 and through holes 800,810. Any method is possible.

  Incidentally, if the through electrodes 610 and 620 are formed so as to protrude from the back surface of the substrate 100, it is convenient for connection to an external electrode.

  FIG. 2 shows a second embodiment.

  In this embodiment, the through holes 800 and 810 are formed in a different direction from the through electrodes 610 and 620, and there is a possibility that the electrode connection from the through electrodes 610 and 620 to the external electrode becomes easy.

  FIG. 3 shows a third embodiment.

  In this embodiment, the electrode is taken out from the electrothermal conversion element 300 at one end by the through electrode 620 and the other end by a general wiring on the electrothermal conversion element 300 surface side. In this example, since only one electrode is connected on the back surface side, there is a possibility that a variety of electrical connections can be facilitated.

(A) Example 1, (b) Sectional drawing of 1st Example including an orifice. Second embodiment. 3rd Example. Conventional example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Base material 200 Insulating layer 210,220 Via hole 300 Electrothermal conversion element 400 Protective film 610,620 Through electrode 700 Wiring electrode 800,810 Through hole (ink supply path)

Claims (4)

In an inkjet recording head comprising an electrothermal conversion element for ejecting ink and a substrate on which at least electrodes connected thereto are formed.
The electrothermal conversion element is formed on one plane of the base, and the electrode formed so as to penetrate from the electrothermal conversion element side of the base to the opposite plane and penetrates the plane opposite from the electrothermal conversion element side of the base An ink jet recording head comprising a through hole formed as described above.   2. The ink jet recording head according to claim 1, wherein the through hole is a liquid path for supplying the discharge liquid to the electrothermal conversion element.   3. The ink jet recording head according to claim 2, wherein the base is made of Si, and an insulating film is formed in advance on a surface on which the electrothermal conversion element is formed, and then the through hole for forming the through electrode is formed. When forming the hole and the through hole for the discharge liquid flow path at the same time and forming the through electrode, the insulating film is formed, and then the conductor is formed. An ink jet recording head characterized in that the through electrode and the through hole are isolated.   4. The ink jet recording head according to claim 3, wherein the electrothermal conversion element is a resistor, and at least one of electrodes for energizing the resistor is a through electrode, and the almost through electrode is directly connected to the resistor. They are in contact with each other or are electrically connected via another electrode formed on the same plane as the resistor, and the resistor and the through electrode are electrically connected by a film having a substantially uniform thickness. An ink jet recording head characterized by being insulated.

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