JP2007245129A - Ultrasonic cleaner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a jet type ultrasonic cleaner having high cleaning capacity and simple structure, cleaning by spraying a cleaning solution applied with ultrasonic vibration to a cleaning object. <P>SOLUTION: An outer periphery of a stainless steel pipe 14 of an outer diameter of 8 mm and an inner diameter of 4 mm is ground to form the outer periphery into a quadrate. Piezoelectric ceramic pieces, piezoelectric elements 13, are jointed to four sides with epoxy resin. The piezoelectric ceramic piece has dimensions of L of 58.5 mm, H of 3 mm and W of 0.51 mm, and has the polarization direction in the direction H. The natural vibration frequency of only the piezoelectric ceramic piece mainly in the direction H in a vibration mode is 1.029MHz. Silver electrodes (not shown) are provided on two faces vertical to the polarization direction. The axial direction of the pipe is set coincidental with the direction L of the piezoelectric ceramic piece. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ultrasonic cleaning apparatus, and more particularly to an injection type ultrasonic cleaning apparatus that performs cleaning by spraying a cleaning liquid to which ultrasonic vibration is applied to an object to be cleaned.

  High-frequency ultrasonic cleaning equipment is used for precision cleaning for fine processing of semiconductor silicon wafers, liquid crystal glass, hard disks, etc., and in particular, jet-type ultrasonic cleaning equipment with little dirt reattachment is used. ing.

  The jet type ultrasonic cleaning device has a structure in which cleaning liquid with ultrasonic vibration is blown out from the nozzle-like jet port and sprayed obliquely against the object to be cleaned to remove the dirt. The cleaning effect is very small.

  FIG. 13 is a conceptual diagram showing a conventional ultrasonic cleaner. As shown in FIG. 13, the nozzle body 1 has a cleaning liquid outlet 7 and a conical nozzle portion 11 that communicates with the cleaning liquid outlet 7 and has an inner diameter that decreases as the cleaning liquid outlet 7 is approached. Further, as shown in the figure, an ultrasonic vibrator 2 is provided above the nozzle portion 11, and this ultrasonic vibrator 2 corresponds to the cleaning liquid 9 supplied into the nozzle body 1 from the cleaning liquid supply pipe 3. Apply ultrasound. The ultrasonic wave applied from the ultrasonic transducer 2 is radiated from the cleaning liquid outlet 7 together with the cleaning liquid 9 and reaches the object 10 to be cleaned which is a substrate. At this time, the cleaning effect can be enhanced by rotating the substrate. When the ultrasonic cleaner is used in this way, the cleaning effect by the cleaning liquid 9 and the cleaning effect by the ultrasonic wave can be obtained. As the cleaning liquid 9 supplied to the ultrasonic cleaner, pure water, ammonia water, hydrogen peroxide water, or the like can be used, and these cleaning liquids 9 may be used at a high temperature of about 80 ° C. .

  By the way, in the ultrasonic cleaning machine, the chemical liquid that is relatively easy to vaporize as described above is used as the cleaning liquid 9 and may be used at a high temperature. Therefore, bubbles are generated inside the cleaning liquid supply pipe 3 and the nozzle body 1. appear. The generated bubbles reach the nozzle body 1 together with the cleaning liquid 9, and the cleaning liquid 9 flows toward the cleaning liquid ejection port 7 in the nozzle main body 1, but the bubbles rise because the specific gravity is lighter than the cleaning liquid 9. Thus, it remains in the vicinity of the ultrasonic transducer 2. When bubbles remain in this way, the ultrasonic energy radiated from the ultrasonic transducer 2 is blocked by the bubbles and is not sufficiently transmitted to the cleaning liquid 9, and the ultrasonic waves radiated from the nozzle body 1 are weakened, resulting in a sufficient cleaning effect. Can't get.

  In addition, when the area occupied by the bubbles is increased, energy is not released from the ultrasonic transducer 2, which not only shortens its life but also causes damage to the ultrasonic transducer 2. For this reason, as shown in FIG. 13, an air vent pipe 4 is provided on the side surface of the nozzle body 1 facing the cleaning liquid supply pipe 3 so that the generated bubbles are discharged from the air vent pipe 4 together with the cleaning liquid 9.

  However, in the ultrasonic cleaning machine shown in FIG. 13, the air vent pipe 4 is below the liquid contact surface with the cleaning liquid 9 of the ultrasonic vibrator 2, so that bubbles remain in the lower part of the ultrasonic vibrator 2. There was a problem. Further, since the nozzle portion 11 of the ultrasonic transducer 2 has a conical shape whose inner diameter decreases as it approaches the cleaning liquid ejection port 7, the jetted cleaning liquid 9 flows straight at the center of the cleaning liquid ejection port 7, but at the end. Since it flows toward the inside, the cleaning liquid 9 converges outside the nozzle body and then disperses. For this reason, the cleaning power varies depending on the distance from the cleaning liquid ejection port 7, and there is also a problem that the cleaning power decreases when the cleaning liquid ejection port 7 is too far away.

  In order to solve the above-described problem of air bubble retention and cleaning liquid 9 focusing, an ultrasonic cleaning machine as shown in FIG. 14 has been proposed. In the ultrasonic cleaning machine shown in FIG. 14, the air vent pipe 4 provided on the side surface of the nozzle body 1 facing the cleaning liquid supply pipe 3 is provided at a position higher than the liquid contact surface of the ultrasonic vibrator 2. . Therefore, most of the cleaning liquid 9 supplied from the cleaning liquid supply pipe 3 is ejected from the cleaning liquid outlet 7, the remaining part is discharged from the air vent pipe 4, and bubbles in the nozzle portion 11 are removed from the air vent pipe 4. At this time, since the position of the air vent pipe 4 is higher than the liquid contact surface of the ultrasonic vibrator 2, the buoyancy of the bubbles acts in the direction of the air vent pipe 4, and the bubbles are generated. It becomes easy to come out.

  Further, a parallel flow path 12 having a uniform inner diameter is provided at the lower part of the nozzle part 11 of the nozzle body 1, and the cleaning liquid 9 supplied from the cleaning liquid supply pipe 3 to the nozzle body 1 is accelerated at the upper part of the nozzle part 11. In addition, since the entire cleaning liquid is arranged to flow in the same direction by passing through the parallel flow path 12, it is possible to maintain the cleaning power with increased momentum. (For example, Patent Documents 1 and 2)

JP-A-10-305248 JP 2001-62350 A

  The conventional ultrasonic cleaner is configured as described above. However, in the conventional ultrasonic cleaner shown in FIG. 13, the ultrasonic waves emitted from the ultrasonic transducer 2 travel in parallel and hit the side surface of the nozzle unit 11. Then, a part of the ultrasonic waves generated from the ultrasonic vibrator 2 pass straight through the cleaning liquid ejection port 7 and a part of the other ultrasonic waves is reflected by the side surface of the nozzle part 11. The ultrasonic waves that have been further reflected at the lower part of the nozzle and passed through the cleaning liquid spout 7 are focused outside the cleaning liquid spout 7. In the ultrasonic cleaner shown in FIG. 13, the number of times of reflection of the ultrasonic wave at the nozzle section 11 is several times. However, in the ultrasonic cleaner shown in FIG. Since the ultrasonic waves are reflected at an angle, there is a problem that the ultrasonic waves are attenuated and the cleaning effect is reduced.

  Further, in the conventional ultrasonic cleaner shown in FIGS. 13 and 14, since the air vent pipe 4 is provided on the side surface of the nozzle body 1, the cleaning liquid is discharged from the air vent pipe together with the bubbles. There was a problem that the pressure of the cleaning liquid sprayed from the outlet 7 was lowered and the cleaning effect was lowered.

  The present invention has been made in view of the above-mentioned problems, and it is possible to improve the cleaning effect by reducing the attenuation of ultrasonic waves and the fluid pressure loss of the cleaning liquid. It is an object of the present invention to provide an injection type ultrasonic cleaning apparatus that performs cleaning.

In a jet type ultrasonic cleaning apparatus that performs cleaning by spraying cleaning liquid with ultrasonic vibrations on the object to be cleaned, a piezoelectric element is bonded to the outer surface of the tube, and the cleaning liquid flowing in the tube is almost orthogonal to the flow direction of the cleaning liquid. The ultrasonic vibration is applied from the direction.

  Assuming that the shape of the piezoelectric element is L in the length direction of the tube, T in the radial direction of the tube, and W in the direction perpendicular to L and T, T is greater than W and L is 2T. It ’s bigger.

  The piezoelectric element has a ring shape and a plurality of piezoelectric elements. And it is located at equal intervals in the length direction of the tube.

  It is possible to provide an injection type ultrasonic cleaning apparatus that performs cleaning by spraying a cleaning liquid to which an ultrasonic vibration is applied, on which an ultrasonic vibration is applied, with small ultrasonic attenuation and fluid pressure loss.

  FIG. 1 is a perspective view showing a basic configuration showing an embodiment of the present invention.

  The outer peripheral portion of a stainless steel tube 14 having an outer diameter of 8 mm and an inner diameter of 4 mm is polished so that the outer peripheral portion is a regular square. Eight piezoelectric ceramics which are the piezoelectric elements 13 are joined to the four sides by an epoxy resin. The dimensions of the piezoelectric ceramic are 58.5 mm for L, 3 mm for H and 0.51 mm for W, and the polarization direction is the H direction as indicated by the arrow. And the natural frequency of the vibration mode mainly in the H direction of the piezoelectric ceramic is 1.029 MHz. Although not shown, silver electrodes are provided on two surfaces perpendicular to the polarization direction. Further, the axial direction of the tube is matched with the L direction of the piezoelectric ceramic. The shape of the piezoelectric ceramic used here is shown in the perspective view of FIG.

  FIG. 2 is a perspective view showing only the tube 14. Although the inside of the tube 14 is exaggerated, it mainly vibrates in the radial direction.

  FIG. 3 further shows the deformation only inside the tube 14, where the dotted line is before deformation and the solid line is deformed. As indicated by the deformed solid line, it expands and contracts in the radial direction.

  FIG. 4 shows the height of the pressure of the cleaning liquid from the position a to the position b of the tube due to the deformation inside the tube shown in FIG. An upward arrow in the figure indicates that the pressure is high, and a downward arrow indicates that the pressure is low. In this way, a close-packed wave is formed in the axial direction.

  Further, in order to efficiently obtain the vibration in the direction of the arrow in FIG. 5, it is desirable to use the longitudinal effect having high electromechanical conversion efficiency of the piezoelectric ceramic that is the piezoelectric element 13, and for that purpose, in the direction H in the direction of the arrow in FIG. Piezoelectric ceramic polarization is required. Longitudinal vibration in which the vibration direction coincides with the polarization direction is a vibration mode with high electromechanical conversion efficiency and high energy efficiency.

  In order to efficiently obtain the desired vibration mode of the vibration in the direction of the arrow in FIG. 5, it is necessary that at least H is greater than W, and the relationship of Equation 1 is necessary.

Formula 1

W <H

  In order to apply ultrasonic energy long in the axial direction, the length L of the piezoelectric ceramic is preferably larger than twice H. When this is expressed by an equation, the relationship of Equation 2 is necessary.

Formula 2

H <L / 2

  If the relationship of Formula 1 and Formula 2 is combined into one formula, the relationship of Formula 3 is obtained.

Formula 3

W <H <L / 2

  When the outside of the shape of the tube 14 is a circle, the surface of the piezoelectric element 13 in contact with the tube is formed in an arc shape as shown in FIG. Here, W is an average value of the arc on the upper surface and the arc on the lower surface. Then, when the long side is L and the height is H, the relationship of the expression 3 is necessary as in FIG. 5 in order to efficiently obtain the vibration in the arrow direction of FIG.

  Next, a voltage having a frequency of about 1 MHz is applied to the piezoelectric ceramic that is the piezoelectric element 13 from an ultrasonic oscillation circuit (not shown), and the cleaning liquid 9 is caused to flow through the cleaning liquid supply port 6 that is one end of the stainless steel circular tube 14. Then, the cleaning liquid 9 to which ultrasonic vibration is applied is ejected from the cleaning liquid outlet 7 at the other end. Then, ultrasonic cleaning is performed on an object to be cleaned (not shown).

  The stainless steel circular tube 14 expands and contracts in the radial direction by the ultrasonic vibration of the piezoelectric element 13 as shown in the conceptual diagrams 2 to 4. When the pipe extends in the radial direction, the pressure of the cleaning liquid 9 in the pipe decreases and the so-called cleaning liquid density becomes rough. When the pipe contracts in the radial direction, the pressure increases and the so-called cleaning liquid density becomes dense.

  The flowing cleaning liquid becomes a dense wave in the flow direction, and the ultrasonic wave is placed on the cleaning liquid and hits the object to be cleaned, so that the cleaning effect by the cleaning liquid and the cleaning effect by the ultrasonic wave are obtained.

  In the conventional ultrasonic cleaning machine of the nozzle type shown in FIG. 13 and FIG. Further, the structure is complicated and the pressure loss of the cleaning liquid is large.

  On the other hand, since the structure of the present invention uses the pipe as it is, the pressure loss of the cleaning liquid can be greatly reduced as compared with the conventional complicated structure. Further, since ultrasonic vibration can be applied to the cleaning liquid from the cleaning liquid inlet 6 to the cleaning liquid outlet 7, it is considered that there is almost no attenuation of the ultrasonic waves.

  Further, since the metal pipe as a pipe can be used as it is as an ultrasonic cleaning apparatus, it can be miniaturized and can be manufactured at low cost as an ultrasonic cleaning apparatus.

Furthermore, the internal cross-sectional area of the metal tube is 3 cm ² or less, preferably 1 cm ² or less. This is because if the tube cross-sectional area is large, the rough wave does not develop sufficiently.

  Although four piezoelectric ceramics are bonded in the radial direction in FIG. 7, a plurality of ring-shaped piezoelectric elements 13 are bonded to the tube 14 as shown in FIG. Also good. The reason why a plurality of ring-shaped piezoelectric elements 13 are used here is to reduce the attenuation of ultrasonic vibration of the tube along the axial direction of the tube 14 as much as possible. For that purpose, the number of ring-shaped piezoelectric elements 13 is preferably three or more.

  The polarization direction of the ring-shaped piezoelectric element 13 is the thickness direction as shown in FIG. The thickness must be smaller than the outer diameter. This condition is for exciting the piezoelectric element 13 to vibrate in the radial direction.

  Furthermore, as shown in the side view of FIG. 9 and the plan view of FIG. 10, the metal tube 14 may be tapered, and the piezoelectric element 13 may be joined to the tapered portion 5. In the conventional configuration, the ultrasonic wave is reflected and attenuated by the taper portion 5, but in the present invention, since the piezoelectric element 13 is joined to the taper portion 5, the taper portion 5 also generates radial stretching vibration. There is no attenuation of ultrasonic waves.

  Also in this embodiment, the tube 14 is made of stainless steel, but other metals may be used, for example, titanium, aluminum or the like.

  In the present embodiment, the material of the tube 14 is a metal, but any material that can propagate ultrasonic waves may be used. For example, a glass tube may be used.

  Furthermore, in the present embodiment, the outer and inner shapes of the tube 14 are circles, but the outer and inner shapes of the tube may be polygons including a quadrangle.

  The ultrasonic cleaning apparatus of the present invention is used for precision cleaning for fine processing of semiconductor silicon wafers, glass for liquid crystals, hard disks, etc., but can also be used as a processing liquid discharge pipe for resist and developer. .

  The ultrasonic cleaning apparatus of the present invention can be used, for example, in which a hole 16 penetrating the central axis of the end mill 15 is provided, and the hole 16 is made to flow into a cleaning liquid or a cutting liquid. That is, it is the structure which provided the drill blade for processing in the outer peripheral part of a pipe | tube. FIG. 11 is a plan view of the end mill 15, and a hole 16 through which a cleaning liquid or a cutting liquid flows is provided in the central axis of the end mill 15. FIG. 12 shows the end mill 15 with the piezoelectric element 13 attached.

  The present invention can be used in a jet type ultrasonic cleaning apparatus that performs cleaning by spraying a cleaning liquid to which ultrasonic vibration is applied to an object to be cleaned.

It is a perspective view which shows embodiment of this invention. It is a perspective view which shows only the pipe | tube of FIG. It is a perspective view which shows the vibration displacement inside a pipe | tube. 4 is a pressure distribution of the cleaning liquid when the vibration displacement of the tube in FIG. It is a perspective view which shows the shape of the piezoelectric ceramic used for FIG. It is a perspective view which shows the shape of another piezoelectric ceramic. It is a perspective view which shows the ultrasonic cleaning machine which attached the annular piezoelectric ceramic to the pipe | tube. It is a perspective view which shows the piezoelectric ceramic used for FIG. It is a top view of the ultrasonic cleaning machine which attached the piezoelectric ceramic to the taper tube. FIG. 10 is a side view of FIG. 9. It is a top view which shows the end mill which provided the hole in the central axis. It is the top view which joined the piezoelectric element to the end mill of FIG. It is side surface sectional drawing which shows the conventional nozzle type ultrasonic cleaning machine. It is side surface sectional drawing which shows another conventional nozzle type ultrasonic cleaner.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Nozzle body 2 Ultrasonic vibrator 3 Cleaning liquid supply pipe 4 Air vent pipe 5 Tapered part 6 Cleaning liquid inflow port 7 Cleaning liquid jet outlet 8 Ultrasonic cleaning apparatus 9 Cleaning liquid 10 Object to be cleaned 11 Nozzle part 12 Parallel flow path 13 Piezoelectric element 14 Pipe 15 End mill 16 holes

Claims (3)

In a jet type ultrasonic cleaning apparatus that performs cleaning by spraying cleaning liquid with ultrasonic vibrations on the object to be cleaned, a piezoelectric element is bonded to the outer surface of the tube, and the cleaning liquid flowing in the tube is almost orthogonal to the flow direction of the cleaning liquid. It is characterized by applying ultrasonic vibration from the direction.   When the shape of the piezoelectric element is L in the length direction of the tube, T in the radial direction of the tube, and W in the direction orthogonal to L and T, T is greater than W and L is greater than 2T. The ultrasonic cleaning apparatus according to claim 1, wherein the ultrasonic cleaning apparatus is large.   The piezoelectric element has a ring shape and a plurality of piezoelectric elements. The ultrasonic cleaning apparatus according to claim 1, wherein the ultrasonic cleaning apparatus is located at substantially equal intervals in the length direction of the tube.

Images