JP4623859B2 - Discharge device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a discharge device, and in particular, a surface of an IC chip or a small electronic component is mounted on a substrate or a circuit pattern for surface mounting is written. The present invention relates to a discharge device that discharges and prints.
[0002]
[Prior art]
Conventionally, for example, in order to surface-mount IC chips or small electronic components on a substrate or to write a circuit pattern for surface mounting, a discharge device has been used to discharge and print solder and electrode paste in a fine pattern. It is used.
[0003]
Such a discharge device that discharges a highly viscous material such as solder or electrode paste must overcome the viscosity of the solder or electrode paste and friction with the inner wall surface of the nozzle hole and discharge a desired amount at a desired speed. Therefore, a reduction in viscosity and friction, such as applying a high pressure to the solder in the nozzle hole and lowering the viscosity of the solder by applying a high temperature, has been dealt with by changing the characteristics of the discharge material.
[0004]
Further, the inner wall surface of the nozzle hole is processed so as to be as smooth as possible in order to reduce friction. In addition, it has been possible to print a pattern having a diameter of about 0.5 mm by a technique such as controlling the discharge amount of solder or the like with a screw-type pressure device.
[0005]
[Problems to be solved by the invention]
In recent years, IC chips and small electronic components have become smaller, and solder for surface mounting such small IC chips and small electronic components on a substrate or circuit patterns for surface mounting have become increasingly fine patterns. Therefore, the conventional discharge device cannot be used.
[0006]
That is, in the conventional discharge device, the discharge diameter can be reduced while maintaining the desired speed and application performance by the friction of the inner wall surface of the nozzle hole in terms of discharging a highly viscous material such as solder or electrode paste. The diameter of several hundred μm was almost the limit. It was very difficult to print thin lines or mounting pads with a width smaller than this.
[0007]
For example, Japanese Patent Application Laid-Open No. 2000-120983 discloses a discharge device including a discharge nozzle and a vibration unit made of a piezoelectric element that shakes off liquid remaining at the tip of the discharge nozzle by vibration. In this discharge apparatus, the vibration unit can excite vibrations in the x and y directions, the entire tip of the discharge nozzle can be vibrated in the x and y directions, and the liquid remaining at the tip of the discharge nozzle can be shaken off by vibration. Since the entire tip of the discharge nozzle vibrates, a fine pattern required in recent years could not be formed.
[0008]
It is an object of the present invention to provide a discharge device capable of printing a liquid such as solder or electrode paste having a high viscosity in a fine pattern.
[0009]
[Means for Solving the Problems]
The discharge device of the present invention is a discharge device comprising a discharge nozzle that discharges a discharge material from a nozzle hole, and a discharge material introduction section that supplies the discharge material to the discharge nozzle, wherein the discharge nozzle is made of a piezoelectric material. Further, an even number of four or more drive electrodes are provided on the outer peripheral surface of the discharge nozzle at predetermined intervals.
[0010]
In such a discharge device, the piezoelectric material is polarized between the adjacent drive electrodes, and a voltage having a different polarity is applied to the adjacent drive electrode at a predetermined drive frequency, so that the nozzle hole of the discharge nozzle is formed. The inner wall surface can be vibrated by standing waves such as a high-frequency ellipse.
[0011]
The resistance at the time of discharge resulting from friction with the inner wall surface of the nozzle hole increases as the discharge diameter decreases. For this reason, the limit which discharges highly viscous materials, such as solder and electrode paste, is about several hundred micrometers. In order to reduce this resistance, it is necessary to reduce the friction at the interface between the inner wall surface and the highly viscous material.
[0012]
When high-frequency vibration due to piezoelectric vibration is generated on the inner wall surface of the nozzle hole, the thin flow boundary layer at the interface between the high-viscosity material that causes friction and the inner wall surface of the nozzle hole can be peeled off from the inner wall surface. The thixotropy of the high viscosity material near the inner wall can be dramatically reduced. As a result, even with a discharge material such as solder or electrode paste having high viscosity, fine wiring and mounting pads can be printed with a diameter of about several tens of μm without controlling discharge at high pressure or high temperature.
[0013]
In addition, by controlling the driving frequency, it is possible to generate a standing wave vibration on the inner wall surface of the nozzle hole and to select a vibration mode that does not change the outer shape of the discharge nozzle. It is possible to apply solder or electrode paste to a recess having a size of about 5 mm without affecting the surroundings such as vibration.
[0014]
The discharge device of the present invention is a discharge device comprising a discharge nozzle that discharges a discharge material from a nozzle hole, and a discharge material introduction unit that supplies the discharge material to the discharge nozzle, wherein the discharge material introduction unit includes It is made of a piezoelectric material, and an even number of four or more drive electrodes are provided on the outer peripheral surface of the discharge material introducing portion at a predetermined interval.
[0015]
In such a discharge device, the piezoelectric material is polarized between the adjacent drive electrodes, and a voltage having a different polarity is applied to the adjacent drive electrode at a predetermined drive frequency, so that the nozzle hole of the discharge nozzle is formed. The inner wall surface can be vibrated by standing waves such as a high-frequency elliptical shape, which allows fine wiring and mounting pads to be printed with a diameter of about several tens of micrometers, even with highly viscous solder and electrode paste discharge materials. be able to.
[0016]
In addition, by controlling the driving frequency, it is possible to generate a standing wave vibration on the inner wall surface of the nozzle hole and to select a vibration mode that does not change the outer shape of the discharge nozzle. It is possible to apply solder or electrode paste to a recess having a size of about 5 mm without affecting the surroundings such as vibration.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
As shown in FIG. 1, the discharge device of the present invention includes a cylindrical discharge nozzle 11 and a discharge material introducing portion 13 formed at one end of the discharge nozzle 11. Although not shown in the drawing, a tube or the like for supplying the discharge material to the discharge material introduction portion 13 is connected to the discharge material introduction portion 13.
[0018]
A nozzle hole 11a for discharging the discharge material is formed in the discharge nozzle 11, and a supply hole for supplying the discharge material to the discharge nozzle 11 is formed in the discharge material introducing portion 13, and the nozzle hole 11a and the supply hole are formed. Communicate. The diameter of the nozzle hole 11a is about several tens of μm, and the outer diameter of the discharge nozzle 11 is about 100 μm. The diameter of the nozzle hole 11a may be large, but is preferably 100 μm or less from the viewpoint of forming a fine pattern.
[0019]
And in this invention, the discharge nozzle 11 is comprised from the piezoelectric material, and as shown in FIG.1 and FIG.2, the rectangular-shaped drive electrode 15 formed in the axial length direction is shown in the outer peripheral surface. Four pieces are formed annularly at a predetermined interval in the width direction. More specifically, the drive electrodes 15 are formed around the outer surface of the cylindrical discharge nozzle 11 at a pitch of 90 degrees, and the shape, thickness, and material thereof are the same. That is, the drive electrode 15 is provided symmetrically in the left-right and up-down directions, and the input potential is applied so that the adjacent drive electrodes have opposite signs. In addition, the electrode is not formed in the inner wall face of the nozzle hole 11a.
[0020]
The drive electrode 15 is connected to an extraction electrode (not shown) formed on the surface of the ejection material introducing portion 13, and these extraction electrodes are connected to a power source in the ejection device that generates an input signal, A voltage having a desired polarity can be applied to each drive electrode 15 via the extraction electrode at a desired frequency.
[0021]
The discharge nozzle 11 is polarized between adjacent drive electrodes 15 and is formed so as to apply a voltage having a different sign to the adjacent drive electrode 15 via the power supply device and the extraction electrode.
[0022]
In the ejection device configured as described above, the drive frequency for vibrating the inner wall surface of the nozzle hole 11a can be selected by changing the drive frequency of the voltage applied to each drive electrode by the power supply device.
[0023]
In addition, by controlling the driving frequency, the inner wall surface of the nozzle hole 11a is vibrated, and the vibration mode in which the outer shape of the discharge nozzle 11 is not changed can be set. FIG. 2 is a conceptual diagram of the discharge nozzle 11 shown in FIG. 1B that vibrates in such a vibration mode. The inner wall surface of the nozzle hole 11a causes an elliptical standing wave vibration. On the other hand, the outer surface of the discharge nozzle 11 is in a mode that vibrates only along the outer surface (circumferential). A black circle (●) indicates a fixed point, and a drive electrode is formed in this portion.
[0024]
The present inventors conducted an FEM analysis with the structure shown in FIG. 1B and investigated what vibration mode is generated by the drive frequency. As a result, the resonance mode corresponding to FIG. 2 exists. It was confirmed. FIG. 3 shows resonance modes obtained by FEM analysis. From FIG. 3, it can be seen that the outer peripheral portion vibrates only along the circumference, and the inner peripheral portion vibrates only the inner wall surface by a standing wave such as an ellipse.
[0025]
Here, the outer shape of the discharge nozzle 11 is 100 μm, the inner diameter is 40 μm, and the piezoelectric material is PZT. In this case, it was confirmed that the vibration mode appears at about 63 MHz.
[0026]
Therefore, in the discharge device according to the present invention, even if the discharge nozzle 11 touches a component already mounted on the substrate or a convex portion of the mounting substrate having unevenness, the outer shape of the discharge nozzle 11 does not change. Since it is in the vibration mode, it does not give a vibration that hinders the structure around the discharge nozzle 11 and only the inner wall surface of the nozzle hole 11a vibrates so as to deform the space. Fine electrode patterns and mounting pads can be discharged and printed on the substrate. For example, a mounting pattern or the like can be applied to a recess having a width of about 100 μm.
[0027]
That is, piezoelectric vibrations are excited by alternately inputting high-frequency electrical signals having different signs to the drive electrodes 15 attached to the outer surface of the discharge nozzle 11, and high-frequency standing wave vibrations are generated on the inner wall surface of the nozzle hole 11a. Appears. In particular, by selecting an appropriate frequency, a vibration mode is selected, as shown in Fig. 2, in which the inner wall vibrates in a standing wave shape such as an ellipse and the outer surface vibrates while maintaining a circular shape. can do. By selecting this vibration, it is possible to apply the solder or the electrode paste to the recess of the discharge nozzle 11 with the size of the outer edge without affecting the surroundings.
[0028]
In addition, when high-frequency vibration due to piezoelectric vibration is generated on the inner wall surface of the nozzle hole 11a, a thin flow boundary layer at the interface between the high-viscosity material that causes friction and the inner wall surface of the nozzle hole 11a can be peeled off from the inner wall surface. The viscosity of the highly viscous material in the vicinity of the inner wall surface can be dramatically reduced by the thixotropy of the highly viscous material. Thereby, even with a discharge material such as solder or electrode paste having high viscosity, fine wiring and mounting pads can be printed with a diameter of about several tens of μm without being driven at high pressure or high temperature.
[0029]
In the case where there is no concern about the influence of vibration on the adjacent fine uneven pattern, it is not necessary to adopt the vibration mode shown in FIG. 2, and a mode in which the vibration of the inner wall surface is large is sufficient.
[0030]
FIG. 4 shows another discharge device of the present invention. In this discharge device, the drive electrode 25 is formed not on the discharge nozzle 11 but on the discharge material introducing portion 13.
[0031]
That is, in this discharge apparatus, a conical discharge material introducing portion 13 is connected to one end of the discharge nozzle 11, and the discharge material introducing portion 13 is made of a piezoelectric material. Four drive electrodes 25 are formed around the discharge material introducing portion 13.
[0032]
In such a discharge device, a drive electrode 25 is formed on the surface of the discharge material introducing portion 13 made of a piezoelectric material away from the discharge nozzle 11, and an electric frequency having a frequency corresponding to a desired vibration mode of the 25 discharge nozzle 11 is formed on the drive electrode. By inputting a signal, the inner wall surface of the nozzle hole 11 a can be vibrated without directly attaching the drive electrode to the outer surface of the discharge nozzle 11, and the nozzle of the discharge nozzle 11 formed at the tip of the discharge material introducing portion 13. Desired piezoelectric vibration can be excited on the inner wall surface of the hole 11a. That is, a vibration mode in which only the inner wall surface of the nozzle hole 11a vibrates can be realized by utilizing the incomplete energy confinement effect of the resonance mode.
[0033]
In this case, it is expected that the most vibrated part is separated from the electrode attachment position, and the peak of the input impedance is expected to be small depending on the drive electrode position. It is necessary to design it so that it can be generated with high accuracy. In the discharge device of FIG. 4, the discharge nozzle 11 does not need to be made of a piezoelectric material, but is made of a metal material that is advantageous for making a cylindrical shape with a small diameter and is less likely to be worn by a highly viscous material. You can choose.
[0034]
As shown in FIGS. 4 and 5, the position where the drive electrode is stretched is the outer peripheral surface of the discharge material introducing portion 13 to which the discharge nozzle 11 is mounted. If the discharge material introducing portion 13 is made of a piezoelectric body, piezoelectric vibration is excited at this portion, and this vibration is transmitted to the discharge nozzle 11. By supplying an input signal having an appropriate frequency, the discharge nozzle 11 generates a desired resonance state, thereby enabling discharge of a target high-viscosity fluid.
[0035]
When there is no concern about the influence of vibration on the fine uneven pattern near the discharge location on the mounting substrate, it is not necessary to dare to adopt the vibration mode shown in FIG. is there. In this case, in order to prevent the center axis of the ejection nozzle from vibrating and causing bleeding or the like in the ejected print pattern, as shown in FIG. It needs to be stretched to keep. At this time, the number of electrodes may be large. However, if the number of electrodes exceeds eight, even in the case of basic vibration, the vibration amplitude is reduced, so that desired characteristics may be deteriorated.
[0036]
【The invention's effect】
In the ejection device of the present invention, since an even number of four or more drive electrodes are provided on the outer peripheral surface of the ejection nozzle at predetermined intervals, the piezoelectric material is polarized between the adjacent drive electrodes and the adjacent drive is provided. By applying voltages of different polarities to the electrodes at a predetermined drive frequency, the inner wall surface of the nozzle hole of the discharge nozzle can be vibrated by standing waves such as a high-frequency elliptical shape, which enables high-viscosity solder. Even with a discharge material such as electrode paste, fine wiring and mounting pads can be printed with a diameter of about several tens of μm without being driven at high pressure or high temperature.
[0037]
In addition, by controlling the driving frequency, it is possible to generate a standing wave vibration on the inner wall surface of the nozzle hole and to select a vibration mode that does not change the outer shape of the discharge nozzle. It is possible to apply solder or electrode paste to a recess having a size of about 5 mm without affecting the surroundings such as vibration.
[Brief description of the drawings]
1A and 1B show a discharge device of the present invention, in which FIG. 1A is a perspective view and FIG. 1B is a cross-sectional view of a discharge nozzle.
FIG. 2 is an explanatory diagram showing a piezoelectric vibration mode generated in a discharge nozzle.
FIG. 3 is a diagram illustrating a simulation result for explaining a vibration mode.
FIG. 4 is a cross-sectional view showing another discharge device of the present invention.
FIG. 5 is a cross-sectional view showing still another ejection device of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Discharge nozzle 11a ... Nozzle hole 13 ... Discharge material introduction part 15, 25 ... Drive electrode

Claims (4)

A discharge device comprising: a discharge nozzle that discharges a discharge material from a nozzle hole; and a discharge material introduction section that supplies the discharge material to the discharge nozzle, wherein the discharge nozzle is made of a piezoelectric material, and the outer peripheral surface of the discharge nozzle And an even number of four or more drive electrodes at predetermined intervals. A discharge apparatus comprising: a discharge nozzle that discharges a discharge material from a nozzle hole; and a discharge material introduction section that supplies the discharge material to the discharge nozzle, wherein the discharge material introduction section is made of a piezoelectric material, and the discharge material introduction An ejection device, wherein an even number of four or more drive electrodes are provided on the outer peripheral surface of the portion at a predetermined interval. 3. The ejection device according to claim 1, wherein the piezoelectric material is polarized between adjacent drive electrodes. The discharge apparatus according to claim 1, wherein an inner wall surface of the nozzle hole of the discharge nozzle vibrates.

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