JP2023051628A - Suction nozzle for mounting - Google Patents

Abstract

To provide a suction nozzle for mounting which has excellent mechanical strength such as bending strength and fracture toughness inherent in zirconia and is particularly suitable for mounting minute components.SOLUTION: In a suction nozzle for mounting with a brim made of partially stabilized zirconia and, if necessary, a conductive material, which has a tip suction surface that suctions and holds an object to be suctioned, and a rear end shaft that is fitted to a cylindrical flange at the rear stage, the outer peripheral surface of the suction nozzle for mounting other than the suction surface at the tip is a non-polished surface, and a flat portion with two molding marks extending in the axial direction is provided at an opposing position of the cross section of the rear end shaft portion.SELECTED DRAWING: Figure 1

Description

Detailed description of the invention

The present invention relates to a suction nozzle for mounting made of partially stabilized zirconia, which is suitably used in an electronic component mounting machine for mounting electronic chip components such as capacitor chips and resistor chips on circuit boards.

2. Description of the Related Art In recent years, in the field of circuit board mounting, the development of electronic component mounting machines capable of mounting minute chip components at high speed and with high precision has been progressing along with the high integration and high precision of boards. In this electronic component mounter, a nozzle for sucking and holding chip components is attached to the tip of a vacuum suction head for sucking outside air, and the head portion reciprocates between a feeder portion and a circuit board. At this time, the chip components vacuum-sucked by the nozzle are mounted on the circuit board after the chip component suction state and component mounting position are determined by image analysis while the head section is moving between the feeder section and the circuit board. This image analysis is performed by irradiating light from the front of the nozzle toward the chip component and the suction surface, and analyzing the shape of the chip component and the position of the electrodes from the difference in the amount of reflected light.

FIG. 4 is a schematic diagram showing an example of a process of mounting chip components onto a circuit board using this electronic component mounting machine.

An electronic component mounting machine 10 shown in FIG. A light 13 that emits light toward the chip component 11 that is sucked and held by the suction nozzle 1, a CCD camera 14 that receives the reflected light from the chip component 11, and an image of the reflected light received by the CCD camera 14. and an image analysis device 15 for processing. Here, as shown in FIG. 2, the mounting suction nozzle 1 has a suction surface 2 at its tip for sucking and holding an electronic component by vacuum suction, and a through-hole communicating from the rear end to the suction surface. It has a structure having a hole 4 in the axial center of the nozzle, and the chip component 11 is sucked and held on the suction surface 2 by sucking outside air from the front end to the rear end of the through hole 4. is.

In this electronic component mounter 10 , when the suction nozzle 1 for mounting moves to the tray 12 and picks up the chip components 11 arranged on the tray 12 , the light 13 is directed toward the chip components 11 picked up by the nozzle 1 . Light is emitted from the body of the chip component 11, and the reflected light reflected by the body of the chip component 11 is received by the CCD camera 14. is measured, and based on the data, the nozzle 1 that has picked up the chip component 11 is moved to a predetermined position on the circuit board (not shown), and the chip component 11 is mounted on the circuit board. .

By the way, in recent years, as described above, the miniaturization of chip parts has progressed along with the high integration and high precision of circuit boards. In addition to being forced to strengthen and further improve dimensional accuracy, etc., a nozzle that causes electrostatic damage to chip parts during mounting, and that allows chip parts that are adsorbed and held by the nozzle to be taken back without separating even if the adsorption is released. new problems caused by static electricity. As a countermeasure, we made the nozzle semi-conductive to remove static electricity, strengthened the nozzle material and made it more precise, and from the viewpoint of heat resistance, etc., we used ceramics as the material, especially partial stability with excellent bending strength and fracture toughness. In addition to the active movement to change to zirconia-made nozzles, when assembling the nozzles into electronic component mounting machines, the rear end shaft of the nozzle is designed to reduce the impact on the components as shown in Fig. 2. It is fitted to the metal cylindrical flange 8 and assembled in an assembled form, but in order to improve the assembly accuracy, the side surface of the nozzle other than the adsorption surface and the rear end shaft part of the nozzle that comes into contact with the flange 8 are polished (hereinafter referred to as In the present invention, secondary processing such as polishing and grinding is simply referred to as "polishing" for assembly.

However, partially stabilized zirconia has the problem that the crystalline phase undergoes a phase transformation due to excessive polishing of the outer peripheral surface of the nozzle after molding and firing and heat history in the operating atmosphere, resulting in a significant decrease in bending strength and fracture toughness. Was. For this reason, for example, Patent Document 1 reports a method for specifying the grain size of zirconia to be used, but it is not possible to suppress the decrease in strength and fracture toughness due to the phase transformation peculiar to zirconia, and the size of the nozzle is greatly reduced. was an obstacle.

WO2009-91061

SUMMARY OF THE INVENTION It is an object of the present invention to provide a nozzle suitable for mounting minute parts, which has excellent mechanical strength such as bending strength and fracture toughness inherent in zirconia.

In order to solve the above problems, the present inventors investigated in detail the material properties of zirconia, especially the effect of heat history during nozzle polishing on mechanical strength, and intensively studied the best way to avoid polishing. Based on the knowledge that polishing the surface of the nozzle greatly reduces the ratio of tetragonal zirconia in the crystal phase and greatly impairs the high mechanical strength peculiar to zirconia, in order to avoid polishing, the nozzle rear end shaft The inventors have found that the most efficient and practical method is to provide a structure in which a flat portion with molding traces is left, and have completed the present invention.

That is, the first aspect of the present invention is made of partially stabilized zirconia, and is provided with a front end attracting surface that attracts and holds an object to be attracted, and a rear end shaft portion that is fitted to a rear cylindrical flange. In a mounting suction nozzle with a flange, the outer peripheral surface of the mounting suction nozzle other than the tip suction surface is a non-polished surface, and two molding marks extending in the axial direction are formed at opposing positions in the cross section of the rear end shaft portion. A second aspect of the present invention is a suction nozzle for mounting, characterized in that a flat portion is provided, and a second aspect of the present invention is directed to the rear end shaft portion of the nozzle of the first aspect, except for the shaft diameter A connecting the flat portions and the flat portion. A suction nozzle for mounting, wherein the ratio A/B of the shaft diameter B is 0.85 to 0.98. A mounting suction nozzle in which 90% or more of the phase is composed of tetragonal crystals, and a fourth invention is the nozzle of the first invention, wherein the nozzle includes a conductivity imparting material, and the tip suction surface and the The suction nozzle for mounting has a resistance value of 10 ² to 10 ¹⁰ Ω with the rear end shaft portion. The suction nozzle for mounting is made of at least one selected from iron, chromium oxide, cobalt oxide, nickel oxide, silicon carbide, and silicon nitride.

According to the present invention, there is provided a suction nozzle for mounting with a flange, which is made of partially stabilized zirconia and has a suction surface for suctioning and holding a chip component at its tip, in which a molding trace is left on the rear end shaft portion of the nozzle. By providing a flat portion, the outer periphery other than the adsorption surface can be used as a non-polished surface, suppressing deterioration in strength such as bending strength and fracture toughness due to changes in the zirconia crystal phase due to polishing. The joint strength with the cylindrical flange is greatly improved, and the practical durability of the nozzle is dramatically improved. It also contributes to the improvement of accuracy.

Further, if the partially stabilized zirconia further contains a conductivity-imparting material, the suction nozzle for mounting of the present invention can cause electrostatic breakdown of the chip components during mounting, and the chip components sucked and held by the nozzle can be prevented from being sucked. It is also possible to solve a new problem caused by the static electricity of the nozzle, such as not separating from the nozzle even after the nozzle is released.

FIG. 1 is a perspective view showing an example of a suction nozzle for mounting according to the present invention. [FIG. 2] is a side cross-sectional view schematically showing an example of assembly of the mounting suction nozzle of the present invention and a subsequent cylindrical flange. [Fig. 3] (a) is an example of a back view of the suction nozzle for mounting of the present invention as seen from the rear end shaft side, and (b) in the same figure is the rear view indicated by the dashed circle in (a). FIG. 4 is a partially enlarged cross-sectional view showing an example of a flat portion provided on the end shaft portion; FIG. 4 is a schematic diagram showing a configuration example of an electronic component mounting apparatus that mounts chip components on a circuit board using an electronic component mounting machine equipped with the mounting suction nozzle of the present invention.

The present invention will be described in detail below.

FIG. 1 is a perspective view showing an example of a mounting suction nozzle of the present invention, and FIG. 2 is a cross-sectional view showing an example of the configuration when this mounting suction nozzle is assembled to a rear cylindrical flange.

A suction nozzle 1 for mounting shown in FIGS. 1 and 2 includes a front end suction surface 2 for sucking and holding an object to be suctioned, and a rear end shaft portion 3 fitted to a cylindrical flange 8 at a rear stage. A suction nozzle for mounting with a collar 5 having a through-hole 4 extending from the rear end shaft portion 3 from the mounting suction nozzle 1, wherein the outer peripheral surface of the mounting suction nozzle 1 other than the tip suction surface 2 is a non-polished surface, and A flat portion 6 having two molding marks 7 extending in the axial direction (see FIG. 3(b) to be described later) is provided at opposing positions of the cross section of the end shaft portion.

The mounting suction nozzle 1 of the present invention is prepared by kneading a mixture of partially stabilized zirconia and, if necessary, a conductivity-imparting material with a binder, a molding aid, etc., and drying the mixture by a known method such as a spray dryer. After preparing a powder or granular raw material, this is injection molded into a nozzle shape with a flange, and a sintered molded body mainly made of partially stabilized zirconia is produced through the process of removing solvent and firing. be.

In the present invention, the zirconia partial stabilizer is preferably one of yttrium oxide, magnesium oxide, calcium oxide, cerium oxide, etc. Among them, yttrium oxide is preferable. The amount of yttrium oxide to be added is 1 to 5 mol%, preferably 2 to 4 mol%. If it is less than 1 mol%, the amount of monoclinic zirconia increases and many cracks occur inside the sintered body, resulting in a decrease in mechanical strength. On the other hand, if the amount of yttrium oxide added exceeds 5 mol%, a large amount of cubic zirconia is formed in the sintered body, and in this case also high mechanical strength cannot be expected. In this case, there arises a problem that the formation of tetragonal zirconia, which produces the stress-induced phase transformation function peculiar to zirconia, is reduced.

In addition, the average crystal grain size of the partially stabilized zirconia used in the present invention is preferably 0.2 to 3.0 μm. If the average crystal grain size is less than 0.2 μm, the stress-induced phase transformation function is not sufficiently exhibited. While excellent mechanical strength such as bending strength and fracture toughness cannot be obtained, if the average crystal grain size is larger than 3.0 μm, deterioration over time at a relatively low temperature of about 100 to 300° C. tends to progress. Otherwise, abrasion resistance, impact resistance, etc. will decrease.

On the other hand, the conductivity-imparting material used as necessary in the present invention is not particularly limited as long as it is a material that can impart conductivity. Among them, oxygen deficient titanium oxide, iron oxide, chromium oxide, cobalt oxide, At least one selected from metal oxides, carbides, and nitrides such as nickel oxide, manganese oxide, silicon carbide, and silicon nitride is preferable because it can impart electrical conductivity with a relatively small amount of addition. The amount of these conductivity imparting materials added is the tip of the nozzle required to avoid troubles caused by static electricity and electrification of the nozzle, such as electrostatic breakdown and take-away of parts when mounting electronic parts, blowing off parts, contamination, etc. and the rear end may be appropriately determined according to the type of the conductivity imparting material so that the electrical resistance value between the and the rear end is 10 ² to 10 ¹⁰ Ω. It is preferably added in an amount of 20 to 40% by weight with respect to zirconia, and in the case of oxygen-deficient titanium oxide, it is preferably added in an amount of 10 to 20% by weight with respect to partially stabilized zirconia.

Here, oxygen-deficient titanium oxide is obtained by reducing and firing a compact obtained by adding titanium dioxide or the like to partially stabilized zirconia under conditions of 1300 to 1500°C in an atmosphere of argon, nitrogen, or the like, thereby It is preferable to have an average crystal grain size of about 0.03 to 0.30 μm, represented by the chemical formula TiOx (1.50≦X≦1.95). That is, titanium dioxide is white at room temperature and is an insulator, but when it is reduced and fired at a high temperature, oxygen deficiency occurs and the color changes from gray to bluish-black to deep black, and electrical conductivity increases. When the X value in the chemical formula TiOx of the oxygen-deficient titanium oxide is less than 1.50, the crystal tends to change to a NaCl type structure, causing volume shrinkage and strength reduction, while the X value is less than 1.95. If it exceeds, the desired mounting nozzle cannot be obtained due to insufficient blackness and conductivity.

In the present invention, the amount of oxygen in the oxygen-deficient titanium oxide, that is, the X value of TiOx is usually determined by oxidizing the oxygen-deficient titanium oxide at a temperature of 500 to 600° C. in the atmosphere to form titanium dioxide, turning black into white. Therefore, the mounting nozzle after reduction firing was subjected to thermal analysis (TG-DTA) at a temperature increase rate of 20°C/min in the atmosphere at room temperature to 1000°C, and the weight increase during that time was measured by oxygen due to oxidation. can be calculated by obtaining the X value as the amount of increase in .

The suction nozzle 1 for mounting of the present invention is made of the above partially stabilized zirconia, the outer peripheral surface of the nozzle other than the suction surface 2 at the tip end of the nozzle is a non-polished surface, and the cross section of the rear end shaft portion of the nozzle is A flat portion 6 having two molding marks 7 extending in the axial direction is provided at opposing positions.

That is, in the conventional suction nozzle for mounting, not only the suction surface for sucking the electronic component, but also the other outer peripheral surface must surely suck and hold the component, convey it to a predetermined position on the circuit board, and mount it. For this reason, in order to increase the accuracy of assembly with other parts such as flanges and sleeve parts in the subsequent stage for fixing the nozzle, it was essential to perform polishing for finishing with high dimensional accuracy and surface accuracy.

However, in the case of zirconia, as described above, mechanical strength such as bending strength and fracture toughness is greatly affected by the state of the crystal phase, that is, the proportion of tetragonal zirconia in the total zirconia crystal phase determined by X-ray diffraction. When the sintered nozzle is polished, part of the crystal phase changes from tetragonal to monoclinic due to thermal history such as frictional heat during polishing. As a result, the stress-induced phase transformation function does not work and high mechanical strength cannot be obtained, which has been a major obstacle to miniaturization of nozzles.

From the above point of view, the suction nozzle 1 for mounting of the present invention has a non-polished outer peripheral surface of the nozzle other than the tip suction surface 2. Specifically, 90% or more of the zirconia crystal phase on the outer peripheral surface of the nozzle is tetragonal. If the proportion of tetragonal crystals is less than 90%, high mechanical strength due to the stress-induced phase transformation cannot be obtained, and miniaturization of nozzles becomes difficult.

Here, the stress-induced phase transformation function of partially stabilized zirconia means that the crystalline state of the zirconia sintered body has three states: cubic, tetragonal, and monoclinic. It refers to the property of undergoing stress-induced phase transformation due to stress and undergoing phase transformation to monoclinic zirconia. At this time, the volume expansion associated with the phase transformation from tetragonal to monoclinic causes minute microcracks to occur around zirconia. However, since the progression of external stress is prevented, the flexural strength and fracture toughness of zirconia are increased.

In the present invention, the tetragonal zirconia of the outer peripheral surface other than the adsorption surface is calculated by X-ray diffraction according to the method described in JP-A-2010-254493. After determining the content (% by volume) of cubic zirconia (measured at a diffraction angle of 70 to 77 degrees), the content of tetragonal zirconia was determined by the following formula.

formula 1

Tetragonal zirconia content (% by volume) = 100 - monoclinic zirconia content - cubic zirconia content

Further, in the present invention, in order to increase the hardness of the suction nozzle for mounting and to make the surface roughness uniform within the range that does not impair the performance of the nozzle, blasting treatment, silicic acid film treatment, HIP treatment, etc. are performed by well-known methods. It may be applied, or may be one to which other ceramic materials such as alumina or molybdenum are added.

The suction nozzle 1 for mounting according to the present invention has a rear end that is fitted to a rear cylindrical flange 8 as shown in FIGS. A flat portion 6 having two molding marks 7 extending in the axial direction is provided at opposing positions in the cross section of the shaft portion 3 .

That is, mounting suction nozzles are usually manufactured by an injection molding machine in consideration of mass productivity. A mold for molding the part that reaches the rear end (hereinafter referred to as "mold (1)") and a mold that molds the part from the rear end of the collar to the rear end of the shaft (hereinafter referred to as "mold (2) ▼”) are arranged in the direction of the nozzle axis, and the raw material for the nozzle is injection molded into the communicating mold (1) and mold (2), and after cooling the molded body, each metal A method is adopted in which the mold is opened and the compact is taken out. At that time, the mold (1) can use an integrated mold because the molded body tapers toward the tip adsorption surface, but a mold that molds the part from the rear end of the collar to the rear end of the shank. (2) requires the use of a pair of split molds separated in two directions in order to take out the compact smoothly. However, with this pair of split molds, molding marks such as burrs and chips remain at the joints of the molds due to pressure during injection molding. had to be removed.

In order to eliminate the need to remove such molding marks, the mounting suction nozzle 1 of the present invention has a flat portion 6 in which two molding marks 7 extending in the axial direction remain at opposing positions on the cross section of the rear end shaft portion of the nozzle. It was established. As shown in FIG. 3, the two flat portions 6 extending in the axial direction are arranged substantially in the center of the molding marks 7 left at the joints of the split molds. A clearance can be created between the inner circumference and the outer circumference of the rear end shaft portion, and even a relatively large molding mark can be accommodated within the clearance, so that it can be used in an unpolished state.

Since the suction nozzle for mounting of the present invention has the flat portion 6 on the rear end shaft portion as described above, it is not necessary to polish the outer peripheral surface of the nozzle, including the removal of molding traces, which has been indispensable until now. In addition to shortening the nozzle processing process and reducing costs, the reduction in strength of the partially stabilized zirconia due to the polishing process described above is suppressed, and when assembling with the cylindrical flange at the later stage, the flange inner circumference and It has a number of excellent features, such as a stronger adhesive fixation due to a larger clearance with the rear end shaft, and suppression of nozzle rotation. It is something to do.

In the nozzle of the present invention, the size of the flat portion 6 is such that the ratio A/B of the shaft diameter A connecting the flat portions shown in FIG. 98, preferably 0.90 to 0.95. The reason for this is that if the shaft diameter ratio is less than 0.85, the strength of the rear end shaft portion is weakened, resulting in durability problems, while if the shaft diameter ratio is greater than 0.98, molding marks are left in the clearance. This is because it cannot be accommodated and requires polishing. In the present invention, since the shaft diameter ratio can be increased as the height of the molding mark is smaller, it is needless to say that the pressure, molding temperature, etc. during injection molding must be optimized.

In the present invention, the flat portion 6 does not necessarily have to be a flat surface, and may have a slightly curved surface or irregularities as long as the molded product can be taken out from the split mold.

Hereinafter, in order to facilitate understanding of the present invention, experimental examples in which changes in mechanical strength of a partially stabilized zirconia molded article were examined depending on whether or not polishing was performed will be described, but the present invention is not limited to these examples.

(Experimental Examples 1-3, Control Examples 1-3)
15% by weight of titanium dioxide having an average particle size of 0.07 μm is added to partially stabilized zirconia having an average crystal particle size of 1.0 μm containing 3 mol % of yttrium oxide, followed by an acrylic or ethylene vinyl acetate binder and wax. A raw material for a compound was prepared by adding ingredients, etc., kneading and drying. Then, this compound raw material was injection molded under conditions of a mold temperature of 40° C. and an extrusion temperature of 150° C. to obtain a molded product. After removing the solvent in the atmosphere at 450 to 900° C., the molded product was fired in an inert gas containing nitrogen as the main component at a temperature of 1100 to 1600° C. for 1 hour. A test piece with a thickness of 40 mm was produced. The obtained test pieces were either unpolished or polished to obtain samples with different contents of tetragonal zirconia in the surface zirconia crystal phase.

The crystal phase, bending strength, and electrical resistance of the obtained samples were evaluated by X-ray diffractometry, and the results are summarized in Table 1. The surface crystal phase of the obtained sample consisted only of monoclinic zirconia and tetragonal zirconia, and the presence of cubic zirconia was not recognized.

In this experimental example and the control example, bending strength and electrical resistance were evaluated by the following methods.

The bending strength was measured for each sample by the method of four-point bending strength according to JISR1601 (2008).

The electrical resistance value was obtained by connecting electrodes to the adsorption surface and the rear end surface of the nozzle illustrated in FIG. voltage was applied, and the resistance value (Ω) between the tip and the rear end of the nozzle was measured.

As can be seen from the results in Table 1, the tetragonal zirconia surface crystal phase of the polished sample is low, resulting in low flexural strength and poor electrical conductivity. On the other hand, it was confirmed that the non-polished sample had a high tetragonal zirconia content and was excellent in bending strength and electrical conductivity. In Table 1, the conductivity is deteriorated by polishing, but this is because the oxygen-deficient titanium oxide used as the conductivity-imparting material was partially oxidized by the polishing in the atmosphere. guessed.

The suction nozzle for mounting of the present invention is excellent in mechanical strength such as bending strength and fracture toughness in the midst of miniaturization of chip parts and increase in mounting speed. Due to the numerous advantages that troubles such as electrostatic breakdown and blow-off of parts occur very little, it can be very suitably used for mounting electronic parts, especially in the field of mounting minute parts.

1; suction nozzle for mounting 2; front end suction surface 3; rear end shaft portion 4; through hole 5; 13; light 14; CCD camera 15; image analysis device

Claims (5)

A suction nozzle for mounting with a flange, which is made of partially stabilized zirconia and has a front end suction surface for suctioning and holding an object to be suctioned and a rear end shaft portion that is fitted to a cylindrical flange at a subsequent stage, the suction nozzle for mounting. is a non-polished outer peripheral surface other than the tip attracting surface, and two flat portions with forming traces extending in the axial direction are provided at opposing positions of the cross section of the rear end shaft portion. Suction nozzle for mounting. 2. The suction for mounting according to claim 1, wherein the cross-sectional shape of the rear end shaft portion has a ratio A/B of a shaft diameter A connecting the flat portions to a shaft diameter B other than the flat portions, which is 0.85 to 0.98. nozzle. 3. The suction nozzle for mounting according to claim 1, wherein 90% or more of the zirconia crystal phase on the outer peripheral surface of the nozzle other than the tip suction surface is composed of tetragonal crystals. 4. The suction for mounting according to any one of claims 1 to 3, wherein said suction nozzle for mounting contains a conductive material, and a resistance value between said front end suction surface and said rear end shaft portion is 10 ² to 10 ¹⁰ Ω. nozzle. 5. The suction nozzle for mounting according to claim 1, wherein said conductivity imparting material is at least one selected from titanium oxide, iron oxide, chromium oxide, cobalt oxide, nickel oxide, silicon carbide and silicon nitride.

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