JP2005059301A - Method for ejecting liquid and impact object - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To adjust the width/height of an impact object easily and appropriately. <P>SOLUTION: In the method for supplying solution to a nozzle 51 having inner diameter not larger than 25 [μm] at the forward end part thereof and ejecting charged solution, in the form of a liquid drop, from the forward end part of the nozzle toward a substrate K disposed oppositely thereto based on an ejection voltage being applied to the solution in the nozzle, the liquid drop is ejected such that the flatness factor D/d satisfies a following expression; 1≤D/d≤3, where d [μm] is the diameter of a flying liquid drop ejected from the forward end part of the nozzle, and D [μm] is the diameter of the liquid drop impacting on the liquid drop receiving surface K1 of the substrate. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a liquid ejection method for ejecting a solution onto a base material and an impacted material landed on the base material.

  As a conventional ink jet recording method, a piezo method that ejects ink droplets by deforming an ink flow path by vibration of a piezoelectric element, a heating element is provided in the ink flow path, and the heating element generates heat to generate bubbles. And a thermal method that discharges ink droplets in response to pressure changes in the ink flow path caused by bubbles, and an electrostatic suction method that charges ink in the ink flow channels and discharges ink droplets by the electrostatic suction force of the ink It has been known.

As a conventional electrostatic suction type ink jet printer, a plurality of convex ink guides that discharge ink from the tip, a counter electrode that is disposed to face the tip of each ink guide and is grounded, and each ink One having a discharge electrode for applying a discharge voltage to ink for each guide is known (for example, see Patent Document 1). The convex ink guide is characterized in that two types of ink guides having different slit widths are prepared, and that two types of droplets can be ejected by properly using these types. .
Further, this conventional ink jet printer discharges ink droplets by applying a pulse voltage to the discharge electrodes, and guides the ink droplets to the counter electrode side by an electric field formed between the discharge electrodes and the counter electrode.

A method of manufacturing a substrate by drawing a circuit wiring pattern on the surface of the substrate using an ink jet technique is also known (see, for example, Patent Document 2).
Japanese Patent Laid-Open No. 11-277747 (FIGS. 2 and 3) JP 2000-33698 A

However, the conventional example has the following problems.
(1) Stability of micro droplet formation Since the nozzle diameter is large, the shape of the droplet discharged from the nozzle is not stable.
(2) High applied voltage In order to discharge fine droplets, miniaturization of the nozzle outlet is an important factor, but the principle of the conventional electrostatic suction method is that the nozzle diameter is large. As a result, the electric field strength at the nozzle tip is weak and it was necessary to apply a high discharge voltage (for example, a very high voltage close to 2000 [V]) in order to obtain the electric field strength necessary for discharging the droplet. . Therefore, in order to apply a high voltage, voltage drive control becomes expensive, and there is also a problem in terms of safety.
(3) Discharge responsiveness In the ink jet apparatus disclosed in the above-mentioned Patent Document 1, discharge is performed by applying a high discharge voltage for the same reason as in (2) above, so that charges move to the center of the meniscus portion. The charge transfer time has an influence on the ejection response, which has been a problem in improving the printing speed.

  Therefore, a first object is to provide a liquid ejection method capable of ejecting micro droplets. At the same time, a second object is to provide a liquid ejection method capable of ejecting stable droplets. Furthermore, a third object is to provide a liquid ejection method capable of ejecting fine droplets and having high landing accuracy. It is a fourth object of the present invention to provide a liquid ejection method that can reduce the applied voltage and is inexpensive and highly safe.

  Further, in Patent Document 1 as a conventional example, in order to perform ink ejection only by applying a pulse voltage to ink, it is necessary to apply a high voltage to an electrode to which the pulse voltage is applied. , (3) there is a disadvantage that it tends to promote the problem.

In addition, when the resistance value of the circuit formed on the substrate is set to a predetermined value, the circuit wiring pattern of the substrate is landed on the droplet receiving surface of the substrate in order to have a predetermined width and height. Although it is necessary to suppress or adjust the wetting and spreading of the droplets, in the case of Patent Document 2 and the like, the droplet receiving surface of the substrate has to be treated with a predetermined hydrophilic or hydrophobic solution. Furthermore, when a circuit wiring pattern having a predetermined height is manufactured by laminating droplets, a structure or the like having a predetermined height is formed on the surface of the substrate along both sides of the wiring pattern. In this way, wetting and spreading of droplets are suppressed.
As described above, the operation for suppressing the wetting and spreading of the droplets on the surface of the base material is complicated, and it is not easy to adjust the width and height of the landing object. Accordingly, a fifth object is to provide a liquid ejection method capable of easily and appropriately adjusting the width and height of the landing object.

According to the first aspect of the present invention, a solution is supplied to a nozzle having an inner diameter of a tip portion of 25 [μm] or less, and the tip portion of the nozzle is moved from the tip portion of the nozzle based on application of a discharge voltage to the solution in the nozzle. A liquid discharge method for discharging a charged solution as droplets to a substrate disposed opposite to a part,
When the diameter of the droplet discharged from the tip of the nozzle and flying is d [μm] and the diameter of the droplet landed on the droplet receiving surface of the substrate is D [μm], the flatness ratio D / d is
1 ≦ D / d ≦ 3
It is characterized in that the liquid droplets are ejected so as to satisfy the following formula.

Here, the diameter of the flying droplet refers to the outer diameter of the flying droplet, and specifically indicates the outer diameter when the flying droplet is regarded as a sphere.
Further, the diameter of the droplet that has landed on the base material indicates the outer diameter when the landed droplet is regarded as a disk having a predetermined thickness.
Hereinafter, the term “nozzle diameter” refers to the internal diameter of the nozzle (the internal diameter of the front end of the nozzle) at the front end where the droplet is discharged. The cross-sectional shape of the liquid discharge hole in the nozzle is not limited to a circle. For example, when the cross-sectional shape of the liquid discharge hole is a polygon, a star, or other shape, the circumscribed circle of the cross-sectional shape is 25 [μm] or less. Hereinafter, in the case of the nozzle diameter or the internal diameter of the tip of the nozzle, the same applies when other numerical values are limited. In addition, the term “nozzle radius” indicates a length that is ½ of this nozzle diameter (inner diameter at the tip of the nozzle).
Furthermore, in the present invention, the “substrate” refers to an object that receives the landing of the droplets of the discharged solution, and is not particularly limited in terms of material. Therefore, for example, when the above configuration is applied to an ink jet printer, a recording medium such as paper or a sheet corresponds to a base material, and when a circuit is formed using a conductive paste, a circuit is formed. The power base should correspond to the substrate.
Moreover, in the said structure, a nozzle or a base material is arrange | positioned so that a droplet receiving surface may oppose the front-end | tip part of a nozzle. The arrangement work for realizing the mutual positional relationship may be performed by either movement of the nozzle or movement of the base material.
The solution in the nozzle is required to be in a charged state for discharging. The solution may be charged by applying a voltage using a dedicated electrode for charging in a range that is not discharged by a discharge voltage applying unit that applies a discharge voltage.

According to the first aspect of the present invention, the diameter of the droplet ejected and flying from the tip portion where the inner diameter of the nozzle is 25 [μm] or less is d [μm], and the droplet receiving surface of the base material is used. When the diameter of the landed droplet is D [μm], the flatness ratio D / d is
1 ≦ D / d ≦ 3
Since the droplets are ejected so as to satisfy the above formula, the width and height of the landing object made of the droplets that have landed on the droplet receiving surface of the substrate can be adjusted. That is, by setting the internal diameter of the tip of the nozzle to 25 [μm] or less, it is possible to discharge minute droplets, and the specific surface area S of the droplets obtained by dividing the surface area S of the droplets by the volume V. / V can be increased. Thereby, the speed at which the solvent of the droplet evaporates can be increased, and drying and solidification can be performed rapidly. If the liquid droplet has a flatness ratio D / d of more than 3, wetting spread becomes large, and it becomes difficult to control the fine shape and ensure the height of the impacted object. In the range of 1 ≦ D / d ≦ 3, it is possible to appropriately form the landing material made of droplets. Specifically, the width of the droplet can be reduced and the height can be increased by bringing the flatness ratio D / d close to 1, while the width of the liquid droplet can be reduced by bringing the flatness ratio D / d close to 3. Large and low in height.
Therefore, the width of the impacted object can be reduced without performing treatment with a predetermined hydrophilic or hydrophobic solution on the surface of the base material or a structure having a predetermined height on the surface of the base material. The height can be adjusted easily and appropriately.
In addition, even when the droplets land on the base material, the droplets that have landed on the substrate are quickly dried and solidified. Therefore, it is possible to appropriately form a landing object structure having a predetermined height and volume.

Further, the above configuration is characterized in that the electric field strength is increased by concentrating the electric field at the tip of the nozzle by using a nozzle having a nozzle diameter of 25 [μm] or less, which is not a conventional nozzle. The diameter reduction of the nozzle will be described in detail later. In such a case, it is possible to discharge liquid droplets without a counter electrode facing the tip of the nozzle. For example, when a substrate is placed facing the nozzle tip in the absence of a counter electrode, and the substrate is a conductor, the surface of the nozzle tip with reference to the droplet receiving surface of the substrate When a mirror image charge of opposite polarity is induced at a symmetrical position and the substrate is an insulator, an image charge of opposite polarity is detected at a symmetrical position determined by the dielectric constant of the substrate with respect to the droplet receiving surface of the substrate. Is induced. Then, the droplets fly by electrostatic force between the charge induced at the nozzle tip and the mirror image charge or the image charge.
However, although the configuration of the present invention can eliminate the need for the counter electrode, the counter electrode may be used in combination. When using the counter electrode together, it is desirable to arrange the base material in a state along the counter surface of the counter electrode and to arrange the counter surface of the counter electrode perpendicular to the direction of droplet discharge from the nozzle, As a result, electrostatic force due to the electric field between the nozzle and the counter electrode can be used together for the induction of the flying electrode, and if the counter electrode is grounded, the charge of the charged droplet is discharged into the air. In addition, it can be escaped through the counter electrode, and the effect of reducing charge accumulation can be obtained.

The invention described in claim 2 is the droplet discharge method according to claim 1,
When the surface area of the droplet discharged from the tip of the nozzle and flying is S and the volume of the droplet is V, the liquid surface area S / V is 0.6 or more. It is characterized by discharging droplets.

  Here, the surface area and volume of the flying droplet are calculated from the outer diameter when the flying droplet is regarded as a sphere.

According to the invention described in claim 2, it is natural that the same effect as that of the invention described in claim 1 can be obtained, in particular, the specific surface area S / V of the droplet is 0.6 or more, Since the droplets can be made very small, the solvent of the droplets ejected from the nozzles and flying, or the droplets landing on the droplet receiving surface of the base material, is accelerated and dried and solidified rapidly. be able to. More specifically, by increasing the specific surface area, it is possible to increase the moving speed and heat transfer speed of the substance from the surface of the droplet. In other words, the amount of movement-controlled evaporation of the substance from the surface of the droplet can be increased, and the amount of solute internal diffusion-controlled movement of the solute in the droplet can be increased, and the evaporation rate of the solvent of the droplet can be greatly increased. can do. Further, since the heat transfer speed can be increased, the latent heat of vaporization required for evaporation of the droplets that have landed on the base material can be rapidly supplied from the base material.
Therefore, by increasing the specific surface area of the droplet, the evaporation rate per volume of the solvent of the droplet can be increased. Since it can be solidified, it is possible to appropriately suppress the wetting and spreading of droplets on the surface of the substrate.

According to a third aspect of the present invention, in the droplet discharge method according to the second aspect,
The droplets are ejected so that the specific surface area S / V of the droplets is 1.0 or more.

  According to the third aspect of the present invention, it is natural that the same effect as that of the second aspect of the present invention can be obtained. In particular, since the specific surface area S / V of the droplet is 1.0 or more. The evaporation rate per volume of the solvent of the droplet can be further increased, and the droplet can be dried and solidified more rapidly. Thereby, suppression of the wetting and spreading of the droplets on the surface of the substrate can be more appropriately performed.

According to a fourth aspect of the present invention, in the droplet discharge method according to any one of the first to third aspects,
The internal diameter of the nozzle is less than 20 [μm].

  According to the invention described in claim 4, it is of course possible to obtain the same effect as that of the invention described in claims 1-3, and in particular, the inner diameter of the nozzle tip is less than 20 [μm]. This narrows the electric field strength distribution. As a result, the electric field can be concentrated. As a result, the formed droplets can be made minute and the shape can be stabilized, and the total applied voltage can be reduced. In addition, immediately after the droplet is ejected from the nozzle, the droplet is accelerated by an electrostatic force acting between the electric field and the electric charge. However, when the droplet is separated from the nozzle, the electric field rapidly decreases, and thereafter, the droplet is decelerated due to air resistance. However, a droplet that is a minute droplet and has a concentrated electric field is accelerated by mirror image force as it approaches the counter electrode. By balancing the deceleration by the air resistance and the acceleration by the mirror image force, it is possible to stably fly the fine droplets and improve the landing accuracy.

According to a fifth aspect of the present invention, in the droplet discharge method according to the fourth aspect,
The internal diameter of the nozzle is 10 [μm] or less.

  According to the fifth aspect of the invention, it is possible to obtain the same effect as the fourth aspect of the invention, in particular, by setting the inner diameter of the nozzle tip to 10 [μm] or less. In addition, it is possible to further concentrate the electric field, and further reduce the size of the droplets and reduce the influence of fluctuations in the distance of the counter electrode on the electric field intensity distribution during flight. It is possible to reduce the influence of the material properties and thickness on the droplet shape and the impact accuracy.

The invention described in claim 6 is the droplet discharge method according to claim 5,
The internal diameter of the nozzle is 8 [μm] or less.

According to the invention described in claim 6, it is possible to obtain the same effect as that of the invention described in claim 5. In particular, by setting the inner diameter of the nozzle tip to 8 [μm] or less. In addition, it is possible to further concentrate the electric field, and further reduce the size of the droplets and reduce the influence of fluctuations in the distance of the counter electrode on the electric field intensity distribution during flight. It is possible to reduce the influence of the material properties and thickness on the droplet shape and the impact accuracy.
Furthermore, by increasing the degree of electric field concentration, the influence of electric field crosstalk, which is a problem in increasing the density of nozzles in the case of increasing the number of nozzles, is reduced, and a higher density can be achieved.

The invention according to claim 7 is the droplet discharge method according to claim 6,
The internal diameter of the nozzle is 4 [μm] or less.

According to the seventh aspect of the invention, it is possible to obtain the same effect as the sixth aspect of the invention, in particular, by setting the inner diameter of the tip of the nozzle to 4 [μm] or less. Therefore, the concentration of the electric field can be significantly increased, the maximum electric field strength can be increased, the shape of the droplet having a stable shape can be reduced, and the initial discharge speed of the droplet can be increased. Thereby, by improving the flight stability, it is possible to further improve the landing accuracy and improve the ejection response.
Furthermore, the degree of concentration of the electric field increases, so that it becomes difficult to be affected by electric field crosstalk, which is a problem in increasing the density of the nozzles when the number of nozzles is increased, and it is possible to further increase the density.
The inner diameter of the nozzle tip is preferably larger than 0.2 [μm]. By making the inner diameter of the nozzle larger than 0.2 [μm], the charging efficiency of the droplets can be improved, and thus the droplet discharge stability can be improved.

According to an eighth aspect of the present invention, the liquid ejecting method according to any one of the first to seventh aspects comprises droplets ejected from the tip of the nozzle and landed on the droplet receiving surface of the substrate. An impact,
When the height in the direction substantially perpendicular to the droplet receiving surface is t [μm] and the distance in the direction substantially horizontal to the droplet receiving surface is W [μm], the aspect ratio W / t is
0.1 ≦ W / t ≦ 100
It is characterized by satisfying the following formula.

According to the eighth aspect of the invention, it is obvious that the same effect as that of the first to seventh aspects of the invention can be obtained. In particular, the direction substantially perpendicular to the droplet receiving surface of the base material of the landing object Is the aspect ratio W / t, where t is the height [tm] and the distance in the direction substantially horizontal to the droplet receiving surface is W [m].
0.1 ≦ W / t ≦ 100
In this range, the aspect ratio W / t of the impacted object, that is, the width and height of the impacted object can be adjusted appropriately.

The invention according to claim 9 is the landing article according to claim 8,
The distance W is characterized by having a width in a direction substantially perpendicular to the longitudinal direction of the landing object extending linearly on the droplet receiving surface.

  According to the ninth aspect of the invention, it is possible to obtain the same effect as that of the eighth aspect of the invention. In particular, the distance W is linear on the droplet receiving surface of the substrate. It is the width in a direction substantially perpendicular to the longitudinal direction of the landing object. That is, it is possible to appropriately adjust the aspect ratio W / t of the landed object formed in a linear shape.

で表される領域において駆動することが好ましい。
ただし、γ：液体の表面張力（N/m）、ε₀：真空の誘電率（F/m）、ｄ：ノズル直径（m）、h：ノズル−基材間距離（m）、ｋ：ノズル形状に依存する比例定数（1.5<k<8.5）とする。
ノズル内の溶液に対して上式（１）の範囲の吐出電圧Ｖの印加が行われる。上式（１）において、吐出電圧Ｖの上限の基準となる左側の項は、従来におけるノズル−対向電極間での電界による液滴吐出を行う場合での限界最低吐出電圧を示す。本発明は、前述したように、ノズルの超微細化による電界集中の効果により、微小液滴の吐出を、従来技術では実現されなかった従来の限界最低吐出電圧よりも低い範囲に吐出電圧Ｖを設定しても、実現することができる。
また、上式（１）における吐出電圧Ｖの下限の基準となる右側の項は、ノズル先端部における溶液による表面張力に抗して液滴の吐出を行うための本発明の限界最低吐出電圧を示す。つまり、この限界最低吐出電圧よりも低い電圧を印加しても液滴の吐出は実行されないが、例えば、この限界最低吐出電圧を境界とするこれより高い値を吐出電圧とし、これより低い値の電圧と吐出電圧とを切り替えることで、吐出動作のオンオフの制御を行うことができる。即ち、電圧の高低の切替のみにより吐出動作のオンオフの制御が可能となる。なお、この場合、吐出のオフ状態に切り替える低電圧値は、限界最低吐出電圧に近いことが望ましい。これにより、オンオフの切替における電圧変化幅を狭小化し、応答性の向上を図ることが可能となるからである。
（５）上記各請求項の構成、上記（１）、（２）、（３）又は（４）の構成において、印加する吐出電圧が1000V以下であることが好ましい。
吐出電圧の上限値をこのように設定することにより、吐出制御を容易とすると共に装置の耐久性の向上及び安全対策の実行により確実性の向上を容易に図ることが可能となる。
（６）上記各請求項の構成、上記（１）、（２）、（３）、（４）又は（５）の構成において、印加する吐出電圧が500V以下であることが好ましい。
吐出電圧の上限値をこのように設定することにより、吐出制御をより容易とすると共に装置の耐久性のさらなる向上及び安全対策の実行により確実性のさらなる向上を容易に図ることが可能となる。
（７）上記各請求項の構成、上記（１）〜（６）のいずれかの構成において、ノズルと基材との距離が500[μm]以下とすることが、ノズル径を微細にした場合でも高い着弾精度を得ることができるので好ましい。
（８）上記各請求項の構成、上記（１）〜（７）のいずれかの構成において、ノズル内の溶液に圧力を印加するように構成することが好ましい。
（９）上記各請求項の構成、上記（１）〜（８）いずれかの構成において、単一パルスによって吐出する場合、

により決まる時定数τ以上のパルス幅Δtを印加する構成としても良い。ただし、ε：溶液の誘電率（F/m）、σ：溶液の導電率（S/m）とする。 Furthermore, in the configuration of each claim,
(1) Preferably, the nozzle is formed of an electrical insulating material, and an electrode for applying a discharge voltage is inserted into the nozzle or plating that functions as the electrode is performed.
(2) In the structure of each of the above claims or the structure of (1), the nozzle is formed of an electrically insulating material, and an electrode is inserted into the nozzle or plating as an electrode is formed, and also for discharge to the outside of the nozzle. It is preferable to provide an electrode.
The ejection electrode outside the nozzle is provided, for example, on the entire circumference or a part of the end surface on the tip side of the nozzle or the side surface on the tip portion side of the nozzle.
According to (1) and (2), in addition to the functions and effects of the above claims, the discharge force can be improved, so that even when the nozzle diameter is further reduced, the liquid droplets can be discharged at a low voltage.
(3) In the configuration of each of the above claims and the configuration of (1) or (2), the base material is preferably formed of a conductive material or an insulating material.
(4) In the configuration of each of the above claims and the configuration of (1), (2) or (3), the discharge voltage V by the discharge voltage applying means is

It is preferable to drive in the region represented by
Where γ: surface tension of liquid (N / m), ε ₀ : vacuum dielectric constant (F / m), d: nozzle diameter (m), h: distance between nozzle and substrate (m), k: nozzle Proportional constant depending on the shape (1.5 <k <8.5).
The ejection voltage V in the range of the above formula (1) is applied to the solution in the nozzle. In the above equation (1), the term on the left, which is the reference for the upper limit of the discharge voltage V, indicates the minimum limit discharge voltage in the case of performing droplet discharge by an electric field between the conventional nozzle and the counter electrode. As described above, according to the present invention, due to the effect of electric field concentration due to the ultra-miniaturization of the nozzle, the discharge of the fine droplets is set to a range lower than the conventional minimum minimum discharge voltage that could not be realized by the prior art. Even if it is set, it can be realized.
Further, the term on the right side, which serves as a reference for the lower limit of the discharge voltage V in the above formula (1), indicates the minimum minimum discharge voltage of the present invention for discharging droplets against the surface tension caused by the solution at the nozzle tip. Show. In other words, even if a voltage lower than this limit minimum discharge voltage is applied, droplet discharge is not executed.For example, a value higher than this limit at the limit minimum discharge voltage is set as a discharge voltage, and a value lower than this is set. By switching between the voltage and the discharge voltage, it is possible to control the on / off of the discharge operation. In other words, it is possible to control the discharge operation on / off only by switching the voltage level. In this case, it is desirable that the low voltage value for switching to the discharge OFF state is close to the limit minimum discharge voltage. This is because it is possible to narrow the voltage change width in the on / off switching and improve the responsiveness.
(5) In the configurations of the above claims and the configurations of (1), (2), (3), or (4), it is preferable that the applied discharge voltage is 1000 V or less.
By setting the upper limit value of the discharge voltage in this way, discharge control can be facilitated, and the reliability of the apparatus can be easily improved by improving the durability of the apparatus and executing safety measures.
(6) In the configurations of the above claims and the configurations of (1), (2), (3), (4) or (5), it is preferable that the discharge voltage to be applied is 500 V or less.
By setting the upper limit value of the discharge voltage in this way, it is possible to make discharge control easier and to further improve the reliability by further improving the durability of the apparatus and executing safety measures.
(7) In the configuration of each of the above claims and the configuration of any one of (1) to (6) above, the distance between the nozzle and the substrate may be 500 [μm] or less when the nozzle diameter is made fine However, it is preferable because high landing accuracy can be obtained.
(8) In the configuration of each of the above claims and the configuration of any of (1) to (7), it is preferable that the pressure is applied to the solution in the nozzle.
(9) In the configuration of each of the above claims and the configuration of any of the above (1) to (8), when discharging by a single pulse,

It is also possible to apply a pulse width Δt greater than or equal to the time constant τ determined by. Where ε is the dielectric constant (F / m) of the solution, and σ is the conductivity of the solution (S / m).

According to the present invention, it is possible to adjust the width and height of an impacted object composed of droplets that have landed on the droplet receiving surface of the substrate. That is, by setting the internal diameter of the tip of the nozzle to 25 [μm] or less, it is possible to discharge minute droplets, and the specific surface area S of the droplets obtained by dividing the surface area S of the droplets by the volume V. Since / V can be increased, the speed at which the solvent of the droplets evaporates can be increased and drying / solidification can be performed rapidly. Furthermore, by defining the flatness ratio D / d within the range of 1 ≦ D / d ≦ 3, the landing object can be properly formed. As a result, the width of the impacted object can be reduced without performing a treatment with a predetermined hydrophilic or hydrophobic solution on the surface of the substrate or a structure having a predetermined height on the surface of the substrate. In addition, the height can be adjusted easily and appropriately.
In addition, even when the droplets land on the base material, the droplets that have landed on the substrate are quickly dried and solidified. Therefore, it is possible to appropriately form a landing object structure having a predetermined height and volume.

Further, according to the present invention, droplets are not ejected by utilizing an electrostatic force generated by an electric field formed between a nozzle and a counter electrode as in the prior art, but the nozzle has an ultrafine diameter (25 [25 [ (μm] or less nozzle diameter), the electric field is concentrated at the tip of the nozzle to increase the electric field strength, and the electrostatic force of the electric field generated between the mirror image charge on the substrate side or the image charge induced at that time. A droplet is flying.
Therefore, it is possible to discharge droplets satisfactorily regardless of whether the substrate is a conductor or an insulator. In addition, it is possible to eliminate the need for the counter electrode. Further, this makes it possible to reduce the number of equipment in the apparatus configuration. Therefore, when the present invention is applied to a commercial ink jet system, it contributes to the improvement of the productivity of the entire system and can also reduce the cost.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples.

ここで、ｑはレイリー限界を与える電荷量（C）、ε₀は真空の誘電率（F/m）、γは溶液の表面張力（N/m）、d₀は液滴の直径（m）である。
上記（３）式で求められる電荷量ｑがレイリー限界値に近いほど、同じ電界強度でも静電力が強く、吐出の安定性が向上するが、レイリー限界値に近すぎると、逆にノズルの液体吐出孔で溶液の霧散が発生してしまい、吐出安定性に欠けてしまう。
ここで、ノズルのノズル径とメニスカス部で吐出する液滴が飛翔を開始する吐出開始電圧、該初期吐出液滴のレイリー限界での電圧値及び吐出開始電圧とレイリー限界電圧値の比との関係を示すグラフを図９に示す。
図９に示すグラフから、ノズル径がφ0.2[μm]からφ4[μm]の範囲において、吐出開始電圧とレイリー限界電圧値の比が0.6を超え、液滴の帯電効率が良い結果となっており、該範囲において安定した吐出が行えることが分かった。
例えば、図１０に示すノズル径とノズルの先端部の強電界（1×10⁶[V/m]以上）の領域の関係で表されるグラフでは、ノズル径がφ0.2[μm]以下になると電界集中の領域が極端に狭くなることが示されている。このことから、吐出する液滴は、加速するためのエネルギーを十分に受けることができず飛翔安定性が低下することを示す。よって、ノズル径はφ0.2[μm]より大きく設定することが好ましい。 The nozzle diameter of the liquid ejection device described in the following embodiments is preferably 25 [μm] or less, more preferably less than 20 [μm], still more preferably 10 [μm] or less, and even more preferably 8 [μm]. ], More preferably 4 [μm] or less. The nozzle diameter is preferably larger than 0.2 [μm]. Hereinafter, the relationship between the nozzle diameter and the electric field strength will be described below with reference to FIGS. Corresponding to FIGS. 1 to 6, the electric field strength distribution is obtained when the nozzle diameter is φ0.2, 0.4, 1, 8, 20 [μm] and the nozzle diameter is φ50 [μm] that is conventionally used as a reference. Show.
Here, in each figure, the nozzle center position indicates the center position of the liquid discharge surface of the liquid discharge hole at the tip of the nozzle. Further, (a) in each figure shows the electric field intensity distribution when the distance between the nozzle and the counter electrode is set to 2000 [μm], and (b) shows the distance between the nozzle and the counter electrode being 100 [ The electric field strength distribution when set to μm] is shown. The applied voltage was fixed at 200 [V] for each condition. The distribution line in the figure shows the range of charge intensity from 1 × 10 ⁶ [V / m] to 1 × 10 ⁷ [V / m].
FIG. 7 is a chart showing the maximum electric field strength under each condition.
1 to 6, it was found that the electric field strength distribution spreads over a wide area when the nozzle diameter is φ20 [μm] (FIG. 5) or more. In addition, it was found from the chart in FIG. 7 that the distance between the nozzle and the counter electrode affects the electric field strength.
For these reasons, when the nozzle diameter is equal to or smaller than φ8 [μm] (FIG. 4), the electric field strength is concentrated and the variation in the distance of the counter electrode hardly affects the electric field strength distribution. Accordingly, when the nozzle diameter is φ8 [μm] or less, stable ejection can be performed without being affected by the positional accuracy of the counter electrode, the material characteristics of the base material, and the thickness.
Next, FIG. 8 shows the relationship between the maximum electric field strength and the strong electric field region when the nozzle diameter of the nozzle and the liquid level are at the tip position of the nozzle.
From the graph shown in FIG. 8, it has been found that when the nozzle diameter is φ4 [μm] or less, the electric field concentration becomes extremely large and the maximum electric field strength can be increased. As a result, the initial discharge speed of the solution can be increased, so that the flight stability of the droplets is increased and the charge transfer speed at the tip of the nozzle is increased, thereby improving the discharge response.
Next, the maximum charge amount that can be charged in the discharged droplets will be described below. The amount of charge that can be charged in the droplet is expressed by the following equation (3) in consideration of the Rayleigh splitting (Rayleigh limit) of the droplet.

Where q is the amount of charge that gives the Rayleigh limit (C), ε ₀ is the dielectric constant in vacuum (F / m), γ is the surface tension of the solution (N / m), d ₀ is the diameter of the droplet (m) It is.
The closer the charge amount q obtained by the above equation (3) is to the Rayleigh limit value, the stronger the electrostatic force is even at the same electric field strength, and the ejection stability is improved. Dispersion of the solution occurs at the discharge holes, resulting in lack of discharge stability.
Here, the relationship between the nozzle diameter of the nozzle and the discharge start voltage at which the droplet discharged from the meniscus starts to fly, the voltage value at the Rayleigh limit of the initial discharge droplet, and the ratio of the discharge start voltage to the Rayleigh limit voltage value The graph which shows is shown in FIG.
From the graph shown in FIG. 9, when the nozzle diameter is in the range of φ0.2 [μm] to φ4 [μm], the ratio of the discharge start voltage to the Rayleigh limit voltage value exceeds 0.6, and the droplet charging efficiency is good. It was found that stable discharge can be performed in this range.
For example, in the graph shown by the relationship between the nozzle diameter and the region of the strong electric field (1 × 10 ⁶ [V / m] or more) at the tip of the nozzle shown in FIG. 10, the nozzle diameter is φ0.2 [μm] or less. Then, it is shown that the region of electric field concentration becomes extremely narrow. This indicates that the ejected droplets cannot receive sufficient energy for acceleration and the flight stability is lowered. Therefore, the nozzle diameter is preferably set to be larger than φ0.2 [μm].

[Liquid ejection device]
(Overall configuration of liquid ejection device)
Hereinafter, the liquid ejection apparatus 100 will be described with reference to FIGS. 11 and 12. FIG. 11 is a cross-sectional view along the nozzle 51 illustrating only the configuration directly related to the solution discharge operation in the liquid discharge apparatus 100 exemplified as an embodiment to which the present invention is applied. FIG. 12 is an explanatory diagram showing the relationship with the voltage applied to the solution. FIG. 12A shows a state where no discharge is performed, and FIG. 12B shows a discharge state.

As shown in FIG. 11, the liquid ejection device 100 has an ultra-fine nozzle 51 that ejects a droplet of a chargeable solution from its tip, and a facing surface that faces the tip of the nozzle 51 and faces the nozzle 51. A counter electrode 23 that supports a substrate K that receives droplets on the surface, a solution supply unit 53 that supplies a solution into the nozzle 51, and a discharge voltage application unit 35 that applies a discharge voltage to the solution in the nozzle 51. It has. A part of the configuration of the nozzle 51 and the solution supply unit 53 and a part of the configuration of the discharge voltage applying means 35 are integrally formed by a nozzle plate 56.
For convenience of explanation, FIG. 12 shows the nozzle 51 with the tip portion facing upward, but in practice, the nozzle 51 is in the horizontal direction or downward, more preferably vertically downward. Used in the state.
Here, the configuration directly related to the liquid droplet ejection of the liquid ejection device 100 will be described first.

(solution)
Examples of the solution discharged by the liquid discharge apparatus 100 include inorganic liquids such as water, COCl ₂ , HBr, HNO ₃ , H ₃ PO ₄ , H ₂ SO ₄ , SOCl ₂ , SO ₂ Cl ₂ , and FSO _3. H etc. are mentioned. Examples of the organic liquid include methanol, n-propanol, isopropanol, n-butanol, 2-methyl-1-propanol, tert-butanol, 4-methyl-2-pentanol, benzyl alcohol, α-terpineol, ethylene glycol, glycerin, Alcohols such as diethylene glycol and triethylene glycol; phenols such as phenol, o-cresol, m-cresol, and p-cresol; dioxane, furfural, ethylene glycol dimethyl ether, methyl cellosolve, ethyl cellosolve, butyl cellosolve, ethyl carbitol, butyl Ethers such as carbitol, butyl carbitol acetate, epichlorohydrin; acetone, methyl ethyl ketone, 2-methyl-4-pentanone, aceto Ketones such as enone; fatty acids such as formic acid, acetic acid, dichloroacetic acid, trichloroacetic acid; methyl formate, ethyl formate, methyl acetate, ethyl acetate, acetic acid-n-butyl, isobutyl acetate, acetic acid-3-methoxybutyl, acetic acid- n-pentyl, ethyl propionate, ethyl lactate, methyl benzoate, diethyl malonate, dimethyl phthalate, diethyl phthalate, diethyl carbonate, ethylene carbonate, propylene carbonate, cellosolve acetate, butyl carbitol acetate, ethyl acetoacetate, cyanoacetic acid Esters such as methyl and ethyl cyanoacetate; nitromethane, nitrobenzene, acetonitrile, propionitrile, succinonitrile, valeronitrile, benzonitrile, ethylamine, diethylamine, ethylenediamine, aniline, N-methylaniline, N, N-dimethylaniline, o-toluidine, p-toluidine, piperidine, pyridine, α-picoline, 2,6-lutidine, quinoline, propylenediamine, formamide, N-methylformamide, N, N-dimethylformamide, N, Nitrogen-containing compounds such as N-diethylformamide, acetamide, N-methylacetamide, N-methylpropionamide, N, N, N ′, N′-tetramethylurea, N-methylpyrrolidone; dimethylsulfoxide, sulfolane and the like Sulfur compounds; hydrocarbons such as benzene, p-cymene, naphthalene, cyclohexylbenzene, cyclohexene; 1,1-dichloroethane, 1,2-dichloroethane, 1,1,1-trichloroethane, 1,1,1,2- Tetrachloroethane, 1,1,2,2-tetrachloro Loethane, pentachloroethane, 1,2-dichloroethylene (cis-), tetrachloroethylene, 2-chlorobutane, 1-chloro-2-methylpropane, 2-chloro-2-methylpropane, bromomethane, tribromomethane, 1-bromopropane, etc. And halogenated hydrocarbons. Further, two or more of the above liquids may be mixed and used as a solution.

Further, when a conductive paste containing a large amount of a substance having high electrical conductivity (silver powder or the like) is used as a solution and discharging is performed, the target substance to be dissolved or dispersed in the above-described liquid is a nozzle. There is no particular limitation except for coarse particles that cause clogging. Conventionally known phosphors such as PDP, CRT, FED and the like can be used without particular limitation. For example, (Y, Gd) BO ₃ : Eu, YO ₃ : Eu, etc. as red phosphors, and Zn ₂ SiO ₄ : Mn, BaAl ₁₂ O ₁₉ : Mn, (Ba, Sr, Mg) O as green phosphors. _{· α-Al 2 O 3:} Mn , etc., as a blue _{phosphor, BaMgAl 14 O 23: Eu,} BaMgAl 10 O 17: Eu and the like. Various binders are preferably added in order to firmly adhere the target substance to the recording medium. Examples of the binder used include celluloses such as ethyl cellulose, methyl cellulose, nitrocellulose, cellulose acetate, and hydroxyethyl cellulose and derivatives thereof; alkyd resins; polymethacrylic acid, polymethyl methacrylate, 2-ethylhexyl methacrylate / methacrylic acid copolymer (Meth) acrylic resins such as lauryl methacrylate / 2-hydroxyethyl methacrylate copolymer and metal salts thereof; poly (meth) acrylamide resins such as poly N-isopropylacrylamide and poly N, N-dimethylacrylamide; polystyrene, acrylonitrile Styrene resins such as styrene copolymers, styrene / maleic acid copolymers, styrene / isoprene copolymers; styrene / n-butyl methacrylate Styrene and acrylic resins such as copolymer; Saturated and unsaturated polyester resins; Polyolefin resins such as polypropylene; Halogenated polymers such as polyvinyl chloride and polyvinylidene chloride; Polyvinyl acetate, polyvinyl chloride and vinyl acetate Polyvinyl resins such as polymers; Polycarbonate resins; Epoxy resins; Polyurethane resins; Polyacetal resins such as polyvinyl formal, polyvinyl butyral, and polyvinyl acetal; Polyethylene such as ethylene / vinyl acetate copolymer and ethylene / ethyl acrylate copolymer resin Resin; Amide resin such as benzoguanamine; Urea resin; Melamine resin; Polyvinyl alcohol resin and its anionic cation modification; Polyvinylpyrrolidone and its copolymer; Polyethylene oxide, carboxyl Alkylene oxide homopolymers, copolymers and cross-linked products such as polyethylene oxide; Polyalkylene glycols such as polyethylene glycol and polypropylene glycol; Polyether polyols; SBR, NBR latex; Dextrin; Sodium alginate; Gelatin and its derivatives; Natural or semi-synthetic resins such as tragacanth gum, pullulan, gum arabic, locust bean gum, guar gum, pectin, carrageenin, glue, albumin, various starches, corn starch, konjac, fungi, agar, soybean protein; terpene resin; ketone resin; Rosin and rosin ester; polyvinyl methyl ether, polyethyleneimine, polystyrene sulfonic acid, polyvinyl sulfonic acid and the like can be used. These resins may be used not only as a homopolymer but also blended within a compatible range.

  When the liquid ejecting apparatus 100 is used as a patterning method, it can be typically used for a display application. Specifically, plasma display phosphor formation, plasma display rib formation, plasma display electrode formation, CRT phosphor formation, FED (field emission display) phosphor formation, FED rib Formation, color filters for liquid crystal displays (RGB colored layers, black matrix layers), spacers for liquid crystal displays (patterns corresponding to black matrices, dot patterns, etc.), and the like. Here, the rib generally means a barrier, and when a plasma display is taken as an example, it is used to separate plasma regions of respective colors. Other applications include micro lenses, semiconductor coatings such as magnetic materials, ferroelectrics, conductive paste (wiring, antenna), etc., and graphic applications such as normal printing, special media (films, cloth, steel plates, etc.) ) Printing, curved surface printing, printing plates of various printing plates, application using the present invention such as adhesives and sealing materials for processing applications, biopharmaceuticals for medical applications (mixing multiple trace components) N), it can be applied to the application of a sample for genetic diagnosis.

(nozzle)
The nozzle 51 is integrally formed with an upper surface layer 56 c of the nozzle plate 56 described later, and is erected vertically from the flat plate surface of the nozzle plate 56. Further, the nozzle 51 is formed with an in-nozzle channel 52 penetrating from the tip of the nozzle 51 along the center of the nozzle.

  The nozzle 51 will be described in further detail. The nozzle 51 has a uniform opening diameter at the tip and an in-nozzle flow path 52, and as described above, these are formed with an ultrafine diameter. As an example of specific dimensions of each part, the internal diameter of the nozzle internal flow path 52 is 30 [μm] or less, further less than 20 [μm], further 10 [μm] or less, further 8 [μm] or less, 4 [μm] or less is preferable, and in the present embodiment, the internal diameter of the in-nozzle flow path 52 is set to 1 [μm]. The external diameter at the tip of the nozzle 51 is set to 2 [μm], the diameter of the base of the nozzle 51 is set to 5 [μm], and the height of the nozzle 51 is set to 100 [μm]. It is formed in a truncated cone shape close to the shape. The inner diameter of the nozzle is preferably larger than 0.2 [μm].

  The shape of the in-nozzle flow path 52 does not have to be a straight line having a constant inner diameter as shown in FIG. For example, as shown in FIG. 13A, the cross-sectional shape at the end portion of the in-nozzle flow path 52 on the solution chamber 54 side, which will be described later, may be rounded. In addition, as shown in FIG. 13B, the inner diameter at the end on the solution chamber 54 side to be described later of the in-nozzle channel 52 is set larger than the inner diameter at the discharge-side end, The inner surface may be formed in a tapered circumferential shape. Furthermore, as shown in FIG. 13C, only the end portion of the in-nozzle flow path 52 on the side of the solution chamber 54 described later is formed in a tapered peripheral surface shape, and the discharge end portion side of the tapered peripheral surface has an inner diameter. It may be formed in a certain straight line shape.

(Solution supply unit)
The solution supply unit 53 is provided in the nozzle plate 56 at a position serving as the root of the nozzle 51 and communicates the solution from the external solution tank (not shown) to the solution chamber 54. A supply path 57 for guiding and a supply pump (not shown) for applying a supply pressure of the solution to the solution chamber 54 are provided.
The supply pump supplies the solution to the tip of the nozzle 51 and supplies the solution while maintaining the supply pressure in a range that does not spill out from the tip (see FIG. 12A).
The supply pump includes a case where a differential pressure due to the arrangement position of the liquid discharge head and the supply tank is used, and may be configured only by a solution supply path without providing a separate solution supply unit. Although it depends on the design of the pump system, it is basically operated when supplying a solution to the liquid discharge head at the start, the liquid is discharged from the liquid discharge head, and the supply of the corresponding solution is performed by the capillary and the convex meniscus. The solution is supplied by optimizing the volume change in the liquid discharge head by the forming means and the pressures of the supply pump.

(Discharge voltage application means)
The discharge voltage application means 35 includes a discharge electrode 58 for applying a discharge voltage provided in a boundary position between the solution chamber 54 and the nozzle flow path 52 inside the nozzle plate 56, and the discharge electrode 58 is always subjected to direct current. And a discharge power supply 31 for applying an ejection pulse voltage that is superimposed on the bias voltage and is used as a potential required for ejection.

The discharge electrode 58 is in direct contact with the solution inside the solution chamber 54 to charge the solution and apply a discharge voltage.
The bias voltage by the bias power supply 30 is applied in a constant manner within a range where the solution is not discharged, thereby reducing in advance the voltage range to be applied during discharge, thereby improving the reactivity during discharge. Yes.

ただし、γ：溶液の表面張力（N/m）、ε₀：真空の誘電率（F/m）、ｄ：ノズル直径（m）、h：ノズル−基材間距離（m）、ｋ：ノズル形状に依存する比例定数（1.5<k<8.5）とする。
一例を挙げると、バイアス電圧はDC300[V]で印加され、パルス電圧は100[V]で印される。従って、吐出の際の重畳電圧は400[V]となる。 The discharge voltage power supply 31 applies the pulse voltage superimposed on the bias voltage only when discharging the solution. At this time, the value of the pulse voltage is set so that the superimposed voltage V satisfies the condition of the following expression (1).

Where γ: surface tension of the solution (N / m), ε ₀ : vacuum dielectric constant (F / m), d: nozzle diameter (m), h: distance between nozzle and substrate (m), k: nozzle Proportional constant depending on the shape (1.5 <k <8.5).
As an example, the bias voltage is applied at DC 300 [V] and the pulse voltage is marked at 100 [V]. Therefore, the superimposed voltage at the time of ejection is 400 [V].

(Nozzle plate)
The nozzle plate 56 includes a base layer 56a positioned in the lowest layer in FIG. 11, a flow path layer 56b that forms a solution supply path positioned above the base layer 56a, and an upper surface layer formed further above the flow path layer 56b. 56c, and the discharge electrode 58 described above is interposed between the flow path layer 56b and the upper surface layer 56c.
The base layer 56a is formed of a silicon substrate or a highly insulating resin or ceramic, forms a soluble resin layer on the base layer 56a, and only a portion following a predetermined pattern for forming the connection path 57 and the solution chamber 54. The insulating resin layer is formed on the removed portion. This insulating resin layer becomes the flow path layer 56b. A discharge electrode 58 is formed on the upper surface of the insulating resin layer by plating with a conductive material (for example, NiP), and an insulating resist resin layer is further formed thereon. Since this resist resin layer becomes the upper surface layer 56 c, this resin layer is formed with a thickness in consideration of the height of the nozzle 51. Then, this insulating resist resin layer is exposed by an electron beam method or a femtosecond laser to form a nozzle shape. The in-nozzle flow path 52 is also formed by exposure and development. Then, the dissolvable resin layer according to the pattern of the in-nozzle supply path 57 and the solution chamber 54 is removed, and the in-nozzle supply path 57 and the solution chamber 54 are opened to complete the nozzle plate 56.

  The material of the nozzle plate 56 and the nozzle 51 is specifically an insulating material such as epoxy, PMMA, phenol, soda glass, or quartz glass, a semiconductor such as Si, or a conductor such as Ni or SUS. There may be. However, when the nozzle plate 56 and the nozzle 51 are formed of a conductor, it is desirable to provide a coating of an insulating material at least on the end surface of the tip of the nozzle 51, more preferably on the peripheral surface of the tip. By forming the nozzle 51 from an insulating material or forming an insulating material film on the surface of its tip, current leakage from the nozzle tip to the counter electrode 23 can be effectively suppressed when a discharge voltage is applied to the solution. This is because it becomes possible.

(Counter electrode)
The counter electrode 23 has a counter surface perpendicular to the protruding direction of the nozzle 51, and supports the base material K along the counter surface. As an example, the distance from the tip of the nozzle 51 to the opposing surface of the opposing electrode 23 is set to 100 [μm].
Further, since the counter electrode 23 is grounded, the ground potential is always maintained. Therefore, when a pulse voltage is applied, a liquid droplet ejected by an electrostatic force generated by an electric field generated between the tip of the nozzle 51 and the opposing surface is guided to the opposing electrode 23 side.
The liquid ejection device 100 ejects liquid droplets by increasing the electric field strength by concentrating the electric field at the tip of the nozzle 51 due to the ultra-miniaturization of the nozzle 51. Although it is possible to discharge droplets, it is desirable that induction by electrostatic force is performed between the nozzle 51 and the counter electrode 23. In addition, the charge of the charged droplet can be released by grounding the counter electrode 23.

(Discharge operation of micro droplets by liquid discharge device)
The discharge operation of the liquid discharge apparatus 100 will be described with reference to FIGS.
The solution is supplied to the in-nozzle channel 52, and in this state, a bias voltage is applied to the solution by the bias power supply 30 via the discharge electrode 58. In this state, the solution is charged, and a meniscus that is recessed in the solution is formed at the tip of the nozzle 51 (FIG. 12A).
Then, when an ejection pulse voltage is applied by the ejection voltage power supply 31, the solution is guided to the distal end side of the nozzle 51 by the electrostatic force due to the electric field strength of the concentrated electric field at the distal end portion of the nozzle 51, and protrudes to the outside. A meniscus is formed, and an electric field is concentrated by the apex of the convex meniscus. Finally, micro droplets are ejected to the counter electrode side against the surface tension of the solution (FIG. 12B).

Since the liquid ejection apparatus 100 ejects droplets by using a nozzle 51 having a small diameter that has not been conventionally used, the electric field is concentrated by the charged solution in the nozzle flow path 52, and the electric field strength is increased. For this reason, a nozzle with a fine diameter that has been considered impossible in practice because the voltage required for ejection is too high for conventional nozzles with a structure that does not concentrate the electric field (for example, an inner diameter of 100 [μm]). The solution can be discharged at a lower voltage than before.
And since it has a fine diameter, it is possible to easily perform control for reducing the discharge flow rate per unit time due to the low nozzle conductance, and sufficiently small droplet diameter without reducing the pulse width (see above). According to each condition, 0.8 [μm]) discharge of the solution is realized.
In addition, since the ejected droplets are charged, the vapor pressure is reduced even for very small droplets and the evaporation is suppressed, so the loss of droplet mass is reduced and the flight is stabilized. , Preventing a drop in droplet landing accuracy.

(Droplet)
Next, liquid droplets discharged from the nozzle 51 will be described.
In the liquid ejection apparatus 100 according to the present invention, the diameter of the droplet ejected from the tip of the nozzle 51 and flying is d [μm], and the diameter of the droplet landed on the droplet receiving surface K1 of the substrate K is D [ μm], the flatness ratio D / d obtained by dividing the diameter D of the droplet landed by the diameter d of the flying droplet is
1 ≦ D / d ≦ 3
The droplets are ejected so as to satisfy the following formula.
Here, the diameter of the flying droplet is the outer diameter of the flying droplet. For example, the flying droplet is regarded as a sphere, and the flying droplet using an ultra-high speed camera (not shown) is used. It is assumed that an equivalent diameter obtained by taking a picture and processing a two-dimensional image and converting the area of the droplet into a circle is shown (see FIG. 17). The diameter of the liquid droplets that have landed on the substrate K is, for example, a laser microscope (see FIG. 1) that is provided substantially perpendicular to the liquid droplet receiving surface K1 of the substrate K, assuming that the landed liquid droplets are disks of a predetermined thickness. A droplet is photographed using a not-shown image, and the captured image is subjected to image processing to indicate the equivalent diameter obtained by converting the area of the droplet into a circle (see FIG. 17).

Means for defining the flatness ratio D / d within the range of 1 ≦ D / d ≦ 3 include (1) adjustment of the specific surface area of the droplet, (2) adjustment of the discharge voltage, (3) adjustment of the solution, 4) Adjustment of nozzle diameter, (5) Adjustment of nozzle-base material distance, etc. are mentioned.
Note that the discharge rate of the droplets from the nozzles may be adjusted by changing the waveform width or waveform shape of the discharge voltage signal, thereby adjusting the flatness ratio D / d. Further, in adjusting the flatness ratio D / d, the temperature of the base material K may be adjusted. In this case, the evaporation rate can be changed by adjusting the heat transfer amount of the droplets landed on the base material K. Because it can.

(1) Adjustment of Specific Surface Area of Droplet The specific surface area S / V of the droplet is a value obtained by dividing the surface area S of the droplet ejected from the tip of the nozzle and flying by the volume V.
Here, the surface area S and volume V of the flying droplet are calculated from the diameter when the flying droplet is regarded as a sphere, for example.
In order to define the flatness ratio D / d within the range of 1 ≦ D / d ≦ 3, the specific surface area S / V of the droplet is preferably 0.6 or more, and 1.0 or more. Is more preferable. That is, by setting the specific surface area S / V of the droplet to at least 0.6 or more, it is possible to obtain a minute droplet having a diameter of 10 [μm] or less. It is possible to increase the speed at which the solvent of the droplets that have landed on the droplet receiving surface K1 of the material K evaporates, and to rapidly dry and solidify the solvent. More specifically, by increasing the specific surface area, it is possible to increase the moving speed and heat transfer speed of the substance from the surface of the droplet. In other words, the amount of movement-controlled evaporation of the substance from the surface of the droplet can be increased, and the amount of solute internal diffusion-controlled movement of the solute in the droplet can be increased, and the evaporation rate of the solvent of the droplet can be greatly increased. can do. In addition, since the heat transfer speed can be increased, the latent heat of vaporization required for evaporation of the droplets that have landed on the base material K can be quickly supplied from the base material K.

(2) Adjustment of discharge voltage By adjusting the magnitude of the discharge voltage applied to the solution in the nozzle, the charge amount of the droplet can be changed to adjust the vapor pressure.

(3) Solution adjustment Solvent adjustment: The lower the boiling point of the solvent, the higher the saturated vapor pressure at a predetermined temperature, and the higher the evaporation rate. Further, the evaporation rate can be changed by adjusting the concentration of the solvent.
Solute adjustment: The internal diffusion rate of a solute can be adjusted by selecting a solvent having an appropriate solubility parameter according to the type of solute.

(4) Adjustment of nozzle diameter By reducing the nozzle diameter, the droplets can be made minute, and the evaporation rate of the solvent from the droplets can be increased.

(5) Adjustment of the distance between the nozzle and the substrate (GAP) By increasing the distance between the nozzle and the substrate, it is possible to reduce the electric field strength. The evaporation rate of the solvent can be increased.

(Landing object)
Next, the landing object will be described.
The landing object according to the present invention is composed of liquid droplets that have landed on the droplet receiving surface K1 of the substrate K, and has a height t [μm] in a direction substantially perpendicular to the liquid droplet receiving surface K1 of the landing object. The aspect ratio W / t obtained by dividing the distance W [μm] in the direction substantially horizontal to the droplet receiving surface K1 is:
0.1 ≦ W / t ≦ 100
It has come to satisfy the formula of
Here, the landing object may extend linearly on the droplet receiving surface K1, and in this case, the distance W in the direction substantially horizontal to the droplet receiving surface K1 of the landing object is The width in the direction substantially perpendicular to the longitudinal direction of the landing object is shown. Thereby, adjustment of the aspect ratio W / t of the landed object formed linearly can be performed appropriately.

The height t of the landing material in the direction substantially perpendicular to the droplet receiving surface K1 of the base material K is determined by using, for example, a laser microscope provided substantially perpendicular to the droplet receiving surface K1 of the base material K. It is assumed that the impacted object is photographed and calculated from the measured average value in the height direction.
Further, the distance W in the direction substantially horizontal to the droplet receiving surface K1 of the base material K of the impacted object was measured by photographing the impacted object using, for example, a laser microscope in the same manner as the height t of the impacted object. Shall.

また、実施例７〜９、比較例３にあっては、銀ナノペースト（ハリマ化成製）を用いた。 Examples of the present invention and comparative examples will be described below.
(solution)
Poly (p-vinylphenol) was dissolved in 2- (2-n-butoxyethoxy) ethyl acetate, and the solids content was 40% by weight (Examples 1 and 2, Examples 10-12) and 10% by weight (implementation). The solution of Example 3, Comparative Examples 1 and 2, 4) was used.
Poly p-vinylphenol was dissolved in ethanol, and the weight solid content ratio was 10% by weight (Examples 4 to 6).
Here, Table 1 shows boiling points and evaporation rate coefficients of 2- (2-n-butoxyethoxy) ethyl acetate and ethanol. The evaporation rate coefficient is measured by ASTM D 3539, and is obtained when the evaporation rate coefficient of butyl acetate is 1.

In Examples 7 to 9 and Comparative Example 3, silver nano paste (manufactured by Harima Chemicals) was used.

(nozzle)
Material: Glass, internal diameter of tip: 2 [μm] (Examples 1 to 5, Examples 7 to 12, Comparative Example 1, Comparative Examples 3 and 4); 12 [μm] (Example 6, Comparative Example) 2)

(Distance between nozzle and substrate (GAP))
100 [μm] (Examples 1-4, Examples 6-12, Comparative Examples 2-4); 2 [μm] (Example 5, Comparative Example 1)

(Discharge voltage)
240 [V] (Examples 7 and 10); 250 [V] (Example 1); 300 [V] (Example 8); 400 [V] (Example 11); 500 [V] (Example 2) -6, Example 9, Comparative Examples 1 and 2); 700 [V] (Example 12, Comparative Example 4); 1000 [V] (Comparative Example 3)

(Calculation of flatness)
A diameter d [μm] of a droplet discharged from a nozzle and flying on a glass substrate as a base material and a diameter D [μm] of a droplet landed on a droplet receiving surface of the glass substrate were measured. A value obtained by dividing the diameter D [μm] by the diameter d [μm] was defined as the flatness ratio D / d.
The diameter d [μm] of the droplet ejected and ejected from the nozzle is obtained by photographing the flying droplet using an ultra-high speed camera, treating the droplet as a sphere, and performing image processing on a two-dimensional image. The area of the droplet was shown as an equivalent diameter in terms of a circle. Here, for example, methods disclosed in Japanese Patent Application Laid-Open Nos. 2001-150658, 2001-150659, and 2001-150696 can be applied to the method for measuring the diameter of the droplet. Specifically, a droplet enlarged through a high-magnification lens is imaged on an image sensor, and a signal output from the image sensor is subjected to image processing. Then, the outer diameter of the droplet was recognized from the density value of the outer shape portion of the droplet of the image information subjected to image processing, and the outer diameter was used as the diameter of the droplet.
In addition, the diameter D [μm] of the droplet landed on the substrate was photographed using a laser microscope (for example, a laser microscope manufactured by Keyence Corporation) provided substantially perpendicular to the droplet receiving surface of the substrate. The droplet was regarded as a disk having a predetermined thickness, and the photographed image was image-processed to show the area of the droplet as a circle equivalent diameter.
Table 2 shows the comparison results of the flatness ratios corresponding to Examples 1 to 6 and Comparative Examples 1 and 2.

(Calculation of specific surface area)
By changing the discharge voltage to 240, 300, 500 and 1000 [V], the droplet diameter was changed, thereby adjusting the specific surface area of the droplet. In each case, the surface area S and the volume V of the droplet are calculated from the diameter d [μm] obtained when the droplet is regarded as a sphere, which is obtained from an image captured by the ultrahigh-speed camera of the flying droplet. The value obtained by dividing the surface area S by the volume V was defined as the specific surface area S / V.
Table 3 shows the comparison results of specific surface areas S / V corresponding to Examples 7 to 9 and Comparative Example 3.

(Aspect ratio calculation)
The weight solid content ratio and discharge voltage in the solution are changed to 240, 400 and 700 [V], and in each case, droplets are ejected from the nozzle 100 times so as to overlap with the droplet receiving surface of the glass substrate. A landing object made of the formed droplets was formed. Then, a height t [μm] in a direction substantially perpendicular to the droplet receiving surface of the landing object and a distance W [μm] in a direction substantially horizontal to the droplet receiving surface of the landing object are calculated, and the distance W [μm] is calculated. Was divided by the height t [μm] to obtain an aspect ratio W / t.
In addition, the height t [μm] of the landing object was obtained by photographing the landing object landed on the glass substrate using a laser microscope and measuring the average height of the landing object. For the distance W [μm] of the impacted object, a value measured by photographing the impacted object using a laser microscope was used in the same manner as the height of the impacted object.
Table 4 shows comparison results of aspect ratios W / t corresponding to Examples 10 to 12 and Comparative Example 4.

  The evaluations in Tables 2 to 4 indicate the degree of deviation from the desired dimension of the dimensions (for example, height) of the impacted object. Specifically, the degree of deviation from the desired dimension is as follows. Those within 10% are indicated by “◎”, those exceeding 10% and within 25% are indicated by “◯”, and those exceeding 25% are indicated by “x”.

(Evaluation of flatness)
<Comparison of discharge voltage>
As shown in Table 2, by setting the discharge voltage to 250 [V] (Example 1), the flatness ratio D / d can be made closer to 1 compared to the case of 500 [V] (Example 2). did it. That is, the droplet volume can be reduced by lowering the discharge voltage, which increases the specific surface area of the droplet, thereby accelerating the evaporation of the solvent of the droplet and reducing the time required for evaporation. Because it can be done. In addition, the electrowetting effect can be reduced by reducing the charge amount of the droplet.
From the above, in order to reduce the flatness ratio D / d, it is considered preferable to reduce the discharge voltage.

<Comparison of solutions>
By setting the weight solid content ratio in the solution to 40% by weight (Example 2), the flatness ratio D / d could be made closer to 1 compared to the case of 10% by weight (Example 3). That is, the time required for evaporation can be shortened by reducing the weight of the solvent in the droplets. It is also considered that the viscosity increases to a power with respect to the solid content.
Compared to the case where 2- (2-n-butoxyethoxy) ethyl acetate was used (Example 3) by setting the distance between the nozzle and the substrate to 100 [μm] and using ethanol as the solvent (Example 4). Thus, the flatness ratio D / d could be made closer to 1. Further, when the distance between the nozzle and the substrate was 20 [μm] (Example 5 and Comparative Example 1), the flatness ratio D / d could be 3 or less by using ethanol as the solvent. . That is, ethanol has a lower boiling point than acetic acid 2- (2-n-butoxyethoxy) ethyl and has a large evaporation rate coefficient, so that it is a solvent having a high evaporation rate.
From the above, in order to reduce the flatness ratio D / d, it is considered preferable to use a solvent having a high solid content ratio in the solution and a high evaporation rate.

<Comparison of distance between nozzle and substrate>
When the solvent type was 2- (2-n-butoxyethoxy) ethyl acetate and the distance between the nozzle and the substrate was 20 [μm] (Comparative Example 1), the flatness ratio D / d exceeded 3, When the distance between the nozzle and the substrate was 100 [μm] (Example 3), the flatness ratio D / d could be 3 or less. Further, when the solvent type is ethanol and the distance between the nozzle and the substrate is 100 [μm] (Example 4), the flattening ratio D / d is made closer to 1 compared to 20 [μm]. I was able to. That is, it is considered that by increasing the distance between the nozzle and the substrate, the electric field strength is decreased, and the evaporation speed is increased by making the droplets smaller.
From the above, in order to reduce the flatness ratio D / d, it is considered preferable to increase the distance between the nozzle and the substrate.

<Nozzle diameter comparison>
When the solvent type was 2- (2-n-butoxyethoxy) ethyl acetate and the nozzle diameter was 12 [μm] (Comparative Example 2), the flatness ratio D / d exceeded 3, but the nozzle diameter was 2 In the case of [μm] (Example 3), the flatness ratio D / d could be 3 or less. Further, by setting the type of solvent to ethanol and the nozzle diameter to 2 [μm] (Example 4), the flatness ratio D / d could be made closer to 1 compared to 12 [μm]. That is, it is considered that by reducing the nozzle diameter, the liquid can be miniaturized, and the evaporation rate of the droplets is increased.
From the above, in order to reduce the flatness ratio D / d, it is considered preferable to reduce the nozzle diameter.

(Evaluation of specific surface area)
As shown in Table 3, when the specific surface area S / V of the droplet is less than 0.6 (Comparative Example 3), that is, when the discharge voltage is large, the droplet diameter increases and the flatness ratio D / Since d becomes large, the wetting and spreading of the droplets is remarkably deteriorated, and it becomes difficult to form a fine structure or a structure having a predetermined height. On the other hand, when the specific surface area S / V of the droplet exceeds 0.6 (Example 9), particularly when it exceeds 1.0 (Examples 7 and 8), that is, when the discharge voltage is reduced. In this case, the droplet diameter can be reduced and the flatness ratio D / d can be reduced. Therefore, it is possible to increase the speed at which the solvent of the droplets ejected from the nozzles and flying, or the droplets landed on the droplet receiving surface of the substrate, evaporate and rapidly dry and solidify. It is thought that it was because it was able to suppress appropriately.
From the above, in order to reduce the flatness ratio D / d, it is considered that the specific surface area S / V should be 0.6 or more, preferably 1.0 or more.

(Aspect ratio evaluation)
<Comparison of solutions>
As shown in Table 4, when the discharge voltage is 700 [V] and the weight solid content ratio in the solution is 10 wt% (Comparative Example 4), the aspect ratio D / t exceeds 100, that is, the droplets As a result, the wetting and spreading of the material significantly deteriorated, and it was difficult to form a fine structure or a structure having a predetermined height. On the other hand, by setting the weight solid content ratio to 40% by weight (Example 12), it was possible to appropriately suppress the wetting and spreading of the droplets and to reduce the aspect ratio D / t to 100 or less.
From the above, in order to reduce the aspect ratio D / t, it is considered preferable to increase the weight solid content ratio in the solution.

<Comparison of discharge voltage>
By reducing the discharge voltage to 700, 400, and 240 [V] (Examples 10 to 12), the droplets can be miniaturized, so that wetting and spreading of the droplets can be appropriately suppressed, and the aspect ratio D / T could be reduced.
From the above, in order to reduce the aspect ratio D / t, it is considered preferable to reduce the discharge voltage.

  Although illustration of the data is omitted, the aspect ratio D / t of the landing object on which the droplets landed 50 times under the conditions of Example 10 was 0.15.

As described above, by setting the inner diameter of the tip of the nozzle 51 to 25 [μm] or less, it is possible to discharge minute droplets and increase the specific surface area S / V of the droplets. In particular, when the specific surface area S / V of the droplet is 0.6 or more, preferably 1.0 or more, the evaporation rate per volume of the solvent of the droplet can be increased. Thus, the droplets that have been dried and landed on the substrate K can be rapidly solidified, and the wetting and spreading of the droplets on the surface of the substrate K can be easily and appropriately suppressed.
Then, within the range of 1 ≦ D / d ≦ 3, the width of the droplet can be reduced and the height can be increased by bringing the flatness D / d close to 1, while the flatness D / d is 3 By making the distance closer to, the width of the droplet can be increased and the height can be decreased.
Therefore, unlike the conventional method, the substrate K can be processed without the treatment with a predetermined hydrophilic or hydrophobic solution on the surface of the substrate K, or the production of a structure having a predetermined height on the surface of the substrate K. It is possible to easily and appropriately adjust the width and height of a landing object made up of droplets that have landed on the surface. In particular, it is possible to appropriately adjust the width and height of a circuit wiring pattern formed linearly on the surface of the substrate K.
In addition, even when the droplets landed on the base material K, the droplets that have landed are quickly dried and solidified, so that the droplets are stacked. Can be performed appropriately, and a structure of an impacted object having a predetermined height and volume can be formed.

Various improvements and design changes may be made without departing from the spirit of the present invention.
For example, in the above embodiment, in order to define the flatness ratio D / d in the range of 1 ≦ D / d ≦ 3, the specific surface area of the droplet, the discharge voltage, the solution, the nozzle diameter, and the nozzle-substrate distance However, the flatness ratio D / d may be regulated within the above range by means other than these.

[Theoretical explanation of liquid ejection device]
Hereinafter, the theoretical explanation of the liquid ejection by the liquid ejection apparatus and the basic example based on this will be described. In addition, all the contents such as the structure of the nozzle in the theory and basic example described below, the characteristics of the material of each part and the discharge liquid, the configuration added around the nozzle, the control conditions regarding the discharge operation, etc. are as much as possible in the above-described embodiment. Needless to say, the above may be applied.

λ_Cは静電吸引力によりノズル先端部からの液滴の吐出を可能とするための溶液液面における成長波長（m）であり、λ_C＝2πγh²/ε₀V²で求められる。

本発明では、静電吸引型インクジェット方式において果たすノズルの役割を再考察し、従来吐出不可能として試みられていなかった領域において、マクスウェル力などを利用することで、微小液滴を形成することができる。
このような駆動電圧低下および微小量吐出実現の方策のための吐出条件等を近似的に表す式を導出したので以下に述べる。
以下の説明は、上記各本発明の実施形態で説明した液体吐出装置に適用可能である。
いま、直径ｄのノズルに導電性溶液を注入し、基材としての無限平板導体からｈの高さに垂直に位置させたと仮定する。この様子を図１４に示す。このとき、ノズル先端部に誘起される電荷は、ノズル先端の半球部に集中すると仮定し、以下の式で近似的に表される。

ここで、Ｑ：ノズル先端部に誘起される電荷（C）、ε₀：真空の誘電率、ε：基材の誘電率（F/m）、h：ノズル−基材間距離（m）、ｄ：ノズル内部の直径（m）、Ｖ：ノズルに印加する総電圧（V）である。α：ノズル形状などに依存する比例定数で、1〜1.5程度の値を取り、特にｄ<<hのときほぼ1程度となる。 (Measures to reduce applied voltage and realize stable discharge of small droplets)
Previously, it was considered impossible to discharge droplets beyond the range determined by the following conditional expression.

λ _C is a growth wavelength (m) on the liquid surface of the solution for enabling discharge of a droplet from the nozzle tip by electrostatic attraction, and is obtained by λ _C = 2πγh ² / ε ₀ V ² .

In the present invention, the role of the nozzle in the electrostatic attraction type ink jet system is reconsidered, and a micro droplet can be formed by utilizing Maxwell force or the like in an area that has not been attempted as impossible in the past. it can.
Formulas representing the discharge conditions and the like for measures for realizing such a drive voltage drop and a small amount of discharge have been derived and will be described below.
The following description is applicable to the liquid ejection apparatus described in the above embodiments of the present invention.
Now, it is assumed that a conductive solution is injected into a nozzle having a diameter d and is positioned perpendicular to the height of h from an infinite plate conductor as a base material. This is shown in FIG. At this time, it is assumed that the charge induced in the nozzle tip is concentrated in the hemisphere at the nozzle tip, and is approximately expressed by the following equation.

Where Q: charge induced at the nozzle tip (C), ε ₀ : vacuum dielectric constant, ε: dielectric constant of substrate (F / m), h: distance between nozzle and substrate (m), d: Diameter (m) inside the nozzle, V: Total voltage (V) applied to the nozzle. α: A proportional constant depending on the nozzle shape and the like, which takes a value of about 1 to 1.5, and is about 1 when d << h.

で与えられる。ここでｋ：比例定数で、ノズル形状などにより異なるが、1.5〜8.5程度の値をとり、多くの場合5程度と考えられる。（P. J. Birdseye and D.A. Smith, Surface Science, 23 (1970) 198-210）。
今簡単のため、ｄ／２＝Ｒとする。これは、ノズル先端部に表面張力で導電性溶液がノズルの半径と同じ半径を持つ半球形状に盛り上がっている状態に相当する。
ノズル先端の液体に働く圧力のバランスを考える。まず、静電的な圧力は、ノズル先端部の液面積をS[m²]とすると、

（７）、（８）、（９）式よりα＝１とおいて、

と表される。 Further, when the substrate as the base material is a conductor substrate, it is considered that a mirror image charge Q ′ having an opposite sign is induced at a symmetrical position in the substrate. When the substrate is an insulator, a video charge Q ′ having an opposite sign is similarly induced at a symmetrical position determined by the dielectric constant.
By the way, the electric field intensity E _loc. [V / m] at the tip of the convex meniscus at the nozzle tip assumes that the radius of curvature of the convex meniscus tip is R [m].

Given in. Here, k is a proportional constant and varies depending on the nozzle shape and the like, but takes a value of about 1.5 to 8.5 and is considered to be about 5 in many cases. (PJ Birdseye and DA Smith, Surface Science, 23 (1970) 198-210).
For simplicity, let d / 2 = R. This corresponds to a state in which the conductive solution swells in a hemispherical shape having the same radius as the nozzle radius due to surface tension at the nozzle tip.
Consider the balance of pressure acting on the liquid at the nozzle tip. First, the electrostatic pressure is S [m ² ] when the liquid area at the nozzle tip is

From the equations (7), (8) and (9), α = 1 is set,

It is expressed.

ここで、γ：表面張力（N/m）、である。
静電的な力により流体の吐出が起こる条件は、静電的な力が表面張力を上回る条件なので、

となる。十分に小さいノズル直径ｄを用いることで、静電的な圧力が、表面張力を上回らせる事が可能である。
この関係式より、Ｖとｄの関係を求めると、

が吐出の最低電圧を与える。すなわち、式（６）および式（１３）より、

が、本発明の動作電圧となる。 On the other hand, if the surface tension of the liquid at the nozzle tip is Ps,

Here, γ: surface tension (N / m).
The conditions under which fluid discharge occurs due to electrostatic force is a condition where the electrostatic force exceeds the surface tension.

It becomes. By using a sufficiently small nozzle diameter d, the electrostatic pressure can exceed the surface tension.
From this relational expression, when the relationship between V and d is obtained,

Gives the lowest discharge voltage. That is, from Equation (6) and Equation (13),

Is the operating voltage of the present invention.

The dependency of the discharge limit voltage Vc on a nozzle having a certain diameter d is shown in FIG. From this figure, it is clear that the discharge start voltage decreases as the nozzle diameter decreases, considering the effect of electric field concentration by the fine nozzles.
In the conventional way of thinking about the electric field, that is, considering only the electric field defined by the voltage applied to the nozzle and the distance between the counter electrodes, the voltage required for ejection increases as the nozzle becomes smaller. On the other hand, if attention is paid to the local electric field strength, the discharge voltage can be reduced by making the nozzle fine.

ここで、ε：溶液の誘電率（F/m）、σ：溶液の導電率（S/m）である。溶液の比誘電率を10、導電率を10^-6 S/m を仮定すると、τ＝1.854×10^-5secとなる。あるいは、臨界周波数をfc[Hz]とすると、

となる。このfcよりも早い周波数の電界の変化に対しては、応答できず吐出は不可能になると考えられる。上記の例について見積もると、周波数としては10 kHz程度となる。このとき、ノズル半径2μｍ、電圧500V弱の場合、ノズル内流量Gは10^-13m³/sと見積もることができるが、上記の例の液体の場合、10kHzでの吐出が可能なので、1周期での最小吐出量は10fl（フェムトリットル、1fl：10^-15 l）程度を達成できる。 The discharge by electrostatic suction is basically charging of a liquid (solution) at the nozzle end. The charging speed is considered to be about a time constant determined by dielectric relaxation.

Here, ε is the dielectric constant (F / m) of the solution, and σ is the conductivity (S / m) of the solution. Assuming that the relative permittivity of the solution is 10 and the conductivity is 10 ⁻⁶ S / m, τ = 1.854 × 10 ⁻⁵ sec. Or, if the critical frequency is fc [Hz],

It becomes. It is considered that the ejection cannot be performed because it cannot respond to the change in the electric field having a frequency faster than fc. Estimating the above example, the frequency is about 10 kHz. At this time, if the nozzle radius is 2 μm and the voltage is less than 500 V, the flow rate G in the nozzle can be estimated to be 10 ⁻¹³ m ³ / s. However, in the case of the liquid in the above example, discharge at 10 kHz is possible, so one cycle The minimum discharge volume can be about 10 fl (femtoliter, 1 fl: 10 ^-15 l).

Each of the above-described embodiments is characterized by the electric field concentration effect at the nozzle tip and the action of the mirror image force induced on the counter substrate, as shown in FIG. For this reason, it is not always necessary to make the substrate or the substrate support conductive as in the prior art or to apply a voltage to these substrates or substrate support. That is, an insulating glass substrate, a plastic substrate such as polyimide, a ceramic substrate, a semiconductor substrate, or the like can be used as the substrate.
In each of the above embodiments, the voltage applied to the electrode may be either positive or negative.
Furthermore, the discharge of the solution can be facilitated by keeping the distance between the nozzle and the substrate at 500 [μm] or less. Although not shown, it is desirable to perform feedback control by detecting the nozzle position so as to keep the nozzle constant with respect to the substrate.
The base material may be placed and held on a conductive or insulating base material holder.

  FIG. 15 is a side sectional view of a nozzle portion of a liquid ejection apparatus as an example of another basic example of the present invention. An electrode 15 is provided on the side surface of the nozzle 1, and a controlled voltage is applied to the nozzle solution 3. The purpose of the electrode 15 is an electrode for controlling the electrowetting effect. If a sufficient electric field is applied to the insulator constituting the nozzle, the Electrowetting effect is expected to occur even without this electrode. However, in this basic example, the role of discharge control is also fulfilled by controlling more positively using this electrode. When the nozzle 1 is composed of an insulator, the tube thickness of the nozzle at the tip is 1 μm, the nozzle inner diameter is 2 μm, and the applied voltage is 300 V, an electrowetting effect of about 30 atm is obtained. This pressure is insufficient for discharge, but is meaningful from the viewpoint of supplying the solution to the nozzle tip, and it is considered that discharge can be controlled by this control electrode.

  FIG. 9 described above shows the nozzle diameter dependency of the discharge start voltage in the present invention. As the liquid ejection device, the one shown in FIG. 11 was used. It became clear that the discharge start voltage decreased as the nozzle became finer, and discharge was possible at a lower voltage than before.

  In each of the above embodiments, the solution discharge condition is a function of each of the nozzle-substrate distance (h), the discharge voltage amplitude (V), and the applied voltage frequency (f). Satisfaction is required as a discharge condition. Conversely, if any one of the conditions is not met, the other parameters must be changed.

This will be described with reference to FIG.
First, for discharge, there is a certain critical electric field Ec that does not discharge unless the electric field is higher than that. This critical electric field varies depending on the nozzle diameter, the surface tension of the solution, the viscosity, and the like, and it is difficult to discharge below Ec. When the critical electric field Ec or higher, that is, the dischargeable electric field strength, there is a generally proportional relationship between the nozzle-base distance (h) and the discharge voltage amplitude (V), and the nozzle-base distance is reduced. The critical applied voltage V can be reduced.
On the contrary, when the distance (h) between the nozzle and the substrate is extremely increased and the applied voltage V is increased, even if the same electric field strength is maintained, bursting or bursting of fluid droplets may occur due to the action of corona discharge. It will occur.

FIG. 1A shows the electric field strength distribution when the nozzle diameter is φ0.2 [μm], and FIG. 1A shows the electric field strength distribution when the distance between the nozzle and the counter electrode is set to 2000 [μm]. 1 (b) shows the electric field intensity distribution when the distance between the nozzle and the counter electrode is set to 100 [μm]. FIG. 2A shows the electric field strength distribution when the nozzle diameter is set to φ0.4 [μm]. FIG. 2A shows the electric field strength distribution when the distance between the nozzle and the counter electrode is set to 2000 [μm]. 2 (b) shows the electric field intensity distribution when the distance between the nozzle and the counter electrode is set to 100 [μm]. FIG. 3A shows the electric field strength distribution when the nozzle diameter is φ1 [μm], and FIG. 3A shows the electric field strength distribution when the distance between the nozzle and the counter electrode is set to 2000 [μm]. b) shows the electric field strength distribution when the distance between the nozzle and the counter electrode is set to 100 [μm]. FIG. 4A shows the electric field intensity distribution when the nozzle diameter is φ8 [μm], and FIG. 4A shows the electric field intensity distribution when the distance between the nozzle and the counter electrode is set to 2000 [μm]. b) shows the electric field strength distribution when the distance between the nozzle and the counter electrode is set to 100 [μm]. FIG. 5A shows the electric field strength distribution when the nozzle diameter is φ20 [μm]. FIG. 5A shows the electric field strength distribution when the distance between the nozzle and the counter electrode is set to 2000 [μm]. b) shows the electric field strength distribution when the distance between the nozzle and the counter electrode is set to 100 [μm]. FIG. 6A shows the electric field strength distribution when the nozzle diameter is φ50 [μm], and FIG. 6A shows the electric field strength distribution when the distance between the nozzle and the counter electrode is set to 2000 [μm]. b) shows the electric field strength distribution when the distance between the nozzle and the counter electrode is set to 100 [μm]. The chart which shows the maximum electric field strength on each condition of FIGS. It is a diagram which shows the relationship between the maximum electric field strength of the meniscus part of the nozzle diameter of a nozzle, and a strong electric field area | region. A line indicating the relationship between the nozzle diameter of the nozzle and the discharge start voltage at which the droplet discharged from the meniscus starts to fly, the voltage value at the Rayleigh limit of the initial discharge droplet, and the ratio of the discharge start voltage to the Rayleigh limit voltage value FIG. It is a graph represented by the relationship between a nozzle diameter and the area | region of the strong electric field of a meniscus part. It is sectional drawing along the nozzle which illustrated only the structure directly related to the discharge operation | movement of a solution among the liquid discharge devices illustrated as one embodiment with which this invention was applied. It is explanatory drawing which shows the relationship with the voltage applied to a solution, Comprising: FIG. 12 (A) is a state which does not discharge, FIG.12 (B) shows a discharge state. FIG. 13A is a partially cutaway perspective view showing an example of another shape of the flow path in the nozzle, FIG. 13A is an example in which the solution chamber is rounded, and FIG. 13B is a flow path inner wall surface. Is a taper circumferential surface, and FIG. 13C shows an example in which the taper circumferential surface and a linear flow path are combined. As an embodiment of the present invention, it is shown to explain the calculation of the electric field strength of the nozzle. 1 is a side sectional view of a liquid discharge mechanism as an example of the present invention. It is a figure explaining the discharge conditions by the relationship of distance-voltage in the liquid discharge apparatus of embodiment of this invention. It is a schematic diagram for demonstrating the flatness of a droplet.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Liquid discharge apparatus 35 Discharge voltage application means 51 Nozzle 60 Supply path 61 Solution storage part K Base material K1 Droplet receiving surface

Claims (9)

A solution is supplied to a nozzle having an inner diameter of a tip portion of 25 [μm] or less, and a substrate disposed opposite to the tip portion from the tip portion of the nozzle is applied based on application of a discharge voltage to the solution in the nozzle. In contrast, a liquid discharge method for discharging a charged solution as droplets,
When the diameter of the droplet discharged from the tip of the nozzle and flying is d [μm] and the diameter of the droplet landed on the droplet receiving surface of the substrate is D [μm], the flatness ratio D / d is
1 ≦ D / d ≦ 3
A liquid discharge method, wherein a liquid droplet is discharged so as to satisfy the following formula.   The droplet is discharged so that the specific surface area S / V of the droplet is 0.6 or more when the surface area of the droplet discharged from the tip of the nozzle is S and the volume of the droplet is V. The droplet discharging method according to claim 1, wherein the droplet is discharged.   The liquid ejection method according to claim 2, wherein the liquid droplets are ejected such that the specific surface area S / V of the liquid droplets is 1.0 or more.   The liquid ejection method according to claim 1, wherein the inner diameter of the nozzle is less than 20 [μm].   The liquid ejection method according to claim 4, wherein the inner diameter of the nozzle is 10 [μm] or less.   The liquid ejection method according to claim 5, wherein the internal diameter of the nozzle is 8 μm or less.   The liquid ejection method according to claim 6, wherein the inner diameter of the nozzle is 4 [μm] or less. A landed object composed of droplets ejected from the tip of the nozzle by the liquid ejection method according to any one of claims 1 to 7 and landed on a droplet receiving surface of the substrate,
When the height in the direction substantially perpendicular to the droplet receiving surface is t [μm] and the distance in the direction substantially horizontal to the droplet receiving surface is W [μm], the aspect ratio W / t is
0.1 ≦ W / t ≦ 100
A landing object characterized by satisfying the following formula. The landing object according to claim 8, wherein the distance W is a width in a direction substantially perpendicular to a longitudinal direction of the landing object extending linearly on the droplet receiving surface.

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