JP2001176932A - Ultrasonic vibrator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ultrasonic vibrator which has stable vibration property even in high loading and realizes good flip-chip bonding. SOLUTION: A vertical vibration transmission part 3 is provided with a combination part 8 of an inertia measure 4 and a deflection vibration part 5, and a body device, and the combination part 8 is provided with a vibration damper 9 for restraining transverse vibration leak. The vibration relief 9 has enough twist rigidity in a pressurizing direction and can relief transverse vibration. At least two deflection vibration parts 5 are provided and shearing force and moment in loading are balanced. Thereby, a ultrasonic vibrator 1 with stable vibration characteristic even in high loading can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic vibrator used for flip-chip bonding, which is a mounting method for bare chips, etc., and ultrasonic fine joining of lead wires in various electronic components.

2. Description of the Related Art Conventionally, a flip-chip mounting method in which an electrode of an electronic component and a mounting substrate are bonded via gold bumps or the like has been used. It is. As a conventional technique in the ultrasonic combined thermocompression bonding method, for example, Japanese Unexamined Patent Publication No.
A system described in 1-74315 is known. FIG. 7 shows an ultrasonic vibrator used in a conventional flip chip mounting method. In FIG. 7, 101 is an ultrasonic vibrator, 102 is a coupling portion used for coupling to a main body device (not shown), 103 is a joining tool, 104 is a flip chip, and 105 is a flip chip 104 formed in advance. Bonding bumps, 106 is a mounting board,
Reference numeral 107 denotes a vibration direction, and the ultrasonic vibrator 101 and the coupling portion 102 have a circular cross-sectional shape. In the configuration shown in FIG. 7, a flip chip 104 on which bonding bumps 105 are formed in advance for face-down bonding is arranged at the tip of the bonding tool 103, and the flip chip 104 is mounted on a mounting substrate to be bonded. Handling is performed so that the positions of the bonding electrodes (not shown) and the bonding bumps 105 match. The mounting board is fixed on a heat stage (not shown), and the temperature of the flip chip 104 and the mounting board 106 is maintained at about 200 degrees. At the time of joining, a pressing force is applied from a main body device (not shown) through the joining portion 102 through the joining portion 102, and the applied pressure is transmitted to the flip chip 104 by the ultrasonic vibrator 101 and the joining tool 103, and the joining force is applied. The bump 105 is thermocompression-bonded. At the same time, the ultrasonic vibration body 101 is supplied with ultrasonic vibration from an ultrasonic vibration source (not shown) and longitudinally vibrates in the vibration direction 106 at its own resonance frequency. The ultrasonic vibration of the ultrasonic vibrating body 101 is transmitted to the joining tool 103 to excite the bending vibration of the joining tool 103, and to vibrate the joining bump 105 via the flip chip 104 to promote the joining.

However, in the prior art shown in FIG. 7, the joining tool and the ultrasonic vibrator are separated. Since the joining tool is worn by repeated joining and needs to be replaced, the joining tool is fastened to the ultrasonic vibrator by a method such as split fastening.
Depending on the fastening state, the excitation state of the flexural vibration of the joining tool becomes unstable, which causes the occurrence of poor joining. In addition, since the increase in the number of bumps on the flip chip requires an increase in the pressing force at the time of joining, a change in the vibration mode due to the occurrence of bending of the joining tool itself, a change in the state of the tool fastening portion, and furthermore, the Induction of torsion that occurs at the joint of the cable and large changes in electrical characteristics such as impedance characteristics in addition to ultrasonic vibration characteristics make it difficult to control the electric circuit system such as resonance frequency tracking, and the joining quality Is significantly reduced. Furthermore, when joining a large chip, the contact portion of the joining tool with the chip must be increased, and as shown in FIG. If there is a great difference, it becomes difficult to excite the bending vibration of the welding tool itself. Therefore, in order to perform good ultrasonic bonding in the conventional technology, the chip is limited to a relatively small chip, and it is necessary to keep the substrate and the flip chip at about 200 degrees and use a thermocompression bonding method together. Also, the ultrasonic flip chip method itself cannot be applied to a chip having low resistance to a rapid temperature gradient. Further, in the structure as shown in FIG. 7, the coupling portion 102 is provided at a node of the vibration of the ultrasonic vibrating body 101, and the ultrasonic vibrating body 101 is formed of several beams (not shown) or a circular flange structure. Is combined with When a large pressing force is applied for joining, the joint is twisted, and an unnecessary vibration component is induced in the vibration direction of the joining tool 103 to reduce the joining property. Alternatively, when the torsional rigidity of the joining portion is high, unnecessary resonance is caused around the resonance frequency originally used for joining due to the influence of the leakage of vibration to the joining portion 102 due to the Poisson's ratio of the ultrasonic vibrator 101 and the attachment to the main body device. This causes problems such as malfunction of control such as frequency tracking and deterioration of bonding property due to induction of unnecessary vibration. SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a high-rigidity ultrasonic vibrator for bonding that has high rigidity and good vibration characteristics even under high load, enables good flip-chip bonding even at low temperatures, and is applicable to large-area chips. The purpose is to provide.

In order to solve such problems, an ultrasonic vibrator according to the present invention comprises an ultrasonic vibrator for generating ultrasonic longitudinal vibration, and an ultrasonic vibrator generated by the ultrasonic vibrator. A longitudinal vibration transmitting unit for transmitting ultrasonic longitudinal vibration, a coupling unit provided at a node of vibration of the longitudinal vibration transmitting unit for coupling with a main unit, and an ultrasonic vibration transmitting unit provided at a part of the coupling unit. A vibration damping part that prevents leakage to the coupling part, an inertial mass provided at the tip of the longitudinal vibration transmitting part, and a flexural vibrating part that branches from the inertial mass and transmits ultrasonic waves, At least two or more flexural vibrating portions are provided, and bonding is performed by ultrasonic vibration of at least one end of the flexural vibrating portion. Further, at the time of joining, a pressing force in a direction perpendicular to a joining surface of the tip of the bending vibration portion is supplied from a main body device connected to the joining portion, and the pressing force and the longitudinal force of the joining portion and the vibration damping portion are supplied. With a configuration in which the torsional rigidity in the axial direction orthogonal to the longitudinal vibration direction of the vibration transmitting unit is higher than the torsional rigidity in the pressing direction, good joining performance can be realized.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is directed to an ultrasonic vibrator for generating ultrasonic longitudinal vibration, and a longitudinal vibration transmitting for transmitting ultrasonic longitudinal vibration generated by the ultrasonic vibrator. A coupling part provided at a node of the vibration of the longitudinal vibration transmitting part for coupling with a main body device; and a vibration provided at a part of the coupling part for preventing leakage of ultrasonic vibration to the coupling part. A relaxation section, an inertial mass section provided at the tip of the longitudinal vibration transmission section, and a flexural vibration section that branches from the inertial mass section and transmits ultrasonic waves, wherein at least two or more flexural vibration sections are provided. And bonding is performed by ultrasonic vibration of at least one end of the bending vibration portion, thereby achieving stable vibration characteristics and enabling good bonding performance. The invention according to claim 2 is an ultrasonic vibrator that generates ultrasonic longitudinal vibration, a longitudinal vibration transmitting unit that transmits ultrasonic longitudinal vibration generated by the ultrasonic vibrator, and a vibration of the longitudinal vibration transmitting unit. A coupling portion provided at the section of the section for coupling with the main device;
A vibration damping portion provided at a part of the coupling portion for preventing leakage of ultrasonic vibration to the coupling portion, an inertial mass portion provided at a tip of the longitudinal vibration transmitting portion, and branching from the inertial mass portion At least two or more flexural vibrating portions for transmitting ultrasonic waves, and joining is performed by ultrasonic vibration using at least one end of the flexural vibrating portion as a joining surface, and a joining surface of the tip of the flexural vibrating portion at the time of joining Is supplied from a main unit connected to the connecting portion in a vertical direction,
The coupling portion and the vibration damping portion have a configuration in which the torsional rigidity in the axial direction orthogonal to the pressing force and the longitudinal vibration direction of the longitudinal vibration transmitting portion is higher than the torsional rigidity in the pressing force direction. Realizes stable vibration characteristics and enables good bonding performance. The invention according to claim 3 is
3. The ultrasonic vibrator according to claim 1, wherein the flexural rigidity of the inertial mass portion in the flexural longitudinal vibration direction is 100 times or more the flexural rigidity of the flexural vibration portion. It realizes stable vibration characteristics by approaching the ideal state and enables good bonding performance. According to a fourth aspect of the present invention, the ultrasonic vibration body according to any one of the first to third aspects has a configuration in which a part or the entirety of the longitudinal vibration transmitting portion has an ultrasonic longitudinal vibration expanding function. As a result, more stable vibration characteristics are realized and good bonding performance is enabled. According to a fifth aspect of the present invention, in the ultrasonic vibrating body according to any one of the first to fourth aspects, a configuration is provided in which a part or all of the flexural vibration portion has an ultrasonic flexural vibration expanding function. As a result, more stable vibration characteristics are realized and good bonding performance is enabled. According to a sixth aspect of the present invention, in the ultrasonic vibrating body according to any one of the first to fifth aspects, a joining tool is provided at a tip of the flexural vibrating portion.
Easy exchange of tools and always enable good bonding performance. According to a seventh aspect of the present invention, there is provided an ultrasonic vibrator that generates ultrasonic longitudinal vibration, a longitudinal vibration transmitting unit that transmits ultrasonic longitudinal vibration generated by the ultrasonic vibrator, and a vibration of the longitudinal vibration transmitting unit. A coupling portion provided at a section of the joint for coupling with the main body device; a vibration reducing portion provided at a part of the coupling portion for preventing leakage of ultrasonic vibration to the coupling portion; and the longitudinal vibration transmitting portion. An inertial mass portion provided at the tip of the device has at least two flexural vibrating portions that transmit ultrasonic waves by branching off from the inertial mass portion, and at least one of the flexural vibrating portions has Bonding is performed by sonic vibration, and at least one of the flexural vibrating portions is configured not to perform bonding, thereby realizing more stable vibration characteristics and enabling good bonding performance. According to an eighth aspect of the present invention, in the ultrasonic vibrating body according to the seventh aspect, a moment generated by a shear force applied to a flexural vibrating portion and an inertial mass portion that perform joining in a state where a load is applied at the time of joining. In this configuration, the moment generated by the shear force applied to the inertial mass portion is balanced by the flexural vibrating portion that does not perform the above, so that more stable vibration characteristics are realized and good bonding performance is enabled. According to a ninth aspect of the present invention, in the ultrasonic vibrator according to the seventh or eighth aspect, the flexural rigidity of the flexural vibrating portion in the inertial mass portion in the vibration direction of the flexural vibrating portion is the flexural rigidity of the flexural vibrating portion. With a configuration of 100 times or more, the boundary condition of the flexural vibrating portion is brought close to an ideal state, and good bonding performance is enabled. The invention according to claim 10 is
The ultrasonic vibration body according to any one of claims 7 to 9, wherein a part or the whole of the longitudinal vibration transmitting portion has a function of expanding the ultrasonic longitudinal vibration, so that more stable vibration characteristics can be obtained. Realized and enables good bonding performance. According to an eleventh aspect of the present invention, in the ultrasonic vibrating body according to any one of the seventh to tenth aspects, a configuration is provided in which a part or all of the flexural vibrating portion has an ultrasonic flexural vibration expanding function. Thereby, more stable vibration characteristics can be realized and bonding can be realized. According to a twelfth aspect of the present invention, in the ultrasonic vibrating body according to any one of the seventh to eleventh aspects, by providing a joining tool at a tip of the flexural vibrating portion, the tool can be easily exchanged to always provide good bonding. Enable performance. According to a thirteenth aspect of the present invention, there is provided an ultrasonic bonding apparatus including the ultrasonic vibrator according to any one of the first to twelfth aspects. Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 6. (Embodiment 1) FIG. 1 is a perspective view of an ultrasonic oscillator according to Embodiment 1 of the present invention. In the figure, 1 is an ultrasonic vibrator, 2 is an ultrasonic vibrator including a piezoelectric element, 3 is a longitudinal vibration transmitting section for transmitting ultrasonic longitudinal vibration generated in the ultrasonic vibrator 2, 4 is an inertial mass section, 5 A flexural vibrating section, 6 is a joining tool, 7 is a tube attaching section for attaching a tube to a suction hole for negatively adsorbing a flip chip to the joining tool, and 8 is connected to a main body device (not shown). 9 is a vibration damping mechanism for preventing the ultrasonic vibration of the longitudinal vibration transmitting section from leaking to the joining section, and 10 is a through hole for fastening to a main unit (not shown). Hereinafter, a method of manufacturing the ultrasonic vibrator of the present invention will be described. First, an ultrasonic oscillation frequency required for bonding used for bonding is determined, and the ultrasonic vibrator 2 is manufactured. The oscillation frequency of the ultrasonic wave depends on the size of the chip to be joined, and it is desirable to select a frequency such that at least the dimension of the chip in the vibration direction becomes 1/20 or less of the wavelength of the ultrasonic wave in the longitudinal vibration transmitting unit 3. . The ultrasonic transducer 2 has a structure in which at least one piezoelectric element is sandwiched between metal blocks on both sides. The piezoelectric element is processed into a desired size using polishing or an ultrasonic processing machine, and electrodes are formed on both opposing surfaces by baking silver or the like, and polarization processing is performed. The metal block is processed to a desired size by general machining such as a lathe, and a laminated structure is formed by bonding or the like. As the piezoelectric element, PZT or lead titanate-based piezoelectric ceramic can be used. Further, as the metal material, aluminum, stainless steel, duralumin, titanium alloy and the like can be used. When mechanical robustness is required, a through hole is manufactured in the piezoelectric element using an ultrasonic machine, etc., and fastening structures such as screws and screw holes are provided in the metal blocks on both sides, making it suitable for sandwiched piezoelectric elements. What is necessary is just to make it be in the state where the proper tightening torque was loaded. If an even number of piezoelectric elements are used and the layers are stacked with the polarization directions reversed in order, the metal blocks on both sides can be used as a common ground, so safety during handling is improved and the electrical impedance can be set low. it can. In order to facilitate wiring, a structure in which a copper foil or the like is sandwiched between piezoelectric ceramics and a part thereof is exposed may be employed. A fastening structure such as a screw is manufactured by machining on the connection side of the metal block for connection with the vertical vibration transmission unit. The manufactured ultrasonic vibrator 2 generates a resonance of 1/2 wavelength of the longitudinal vibration mode or an odd multiple thereof in the longitudinal direction at a desired frequency, and becomes an ultrasonic vibration source. Next, the longitudinal vibration transmitting section 3, the inertial mass section 4, the flexural vibration section 5, and the connecting section 8 are integrally manufactured. Suitable materials include aluminum, stainless steel, duralumin, and titanium alloy. As shown in FIG.
The coupling portion 8 is provided with a vibration damping mechanism 9. Although not explicitly shown in FIG. 1, when it is necessary to adsorb the chip to the joining tool 6, a suction hole is provided through the flexural vibration section 5 and the inertial mass section 4. For the entire production, a combination of general machining such as a milling machine and a drilling machine, or a wire electric discharge machining can be used. The dimension of the inertial mass section 4 in the longitudinal vibration direction is set to a length that is equal to or less than 1/15 of the wavelength of the ultrasonic wave in the longitudinal vibration transmission section 3. The dimension in the direction perpendicular to the longitudinal vibration direction is 1
It is desirably set to be equal to or less than a half wavelength, and desirably set to be equal to or less than a quarter. The dimensions of the flexural vibration section 5 in the longitudinal vibration direction and the width direction are set to be equal to or smaller than the dimensions of the inertial mass section 4 in the longitudinal vibration direction and the width direction. The length dimension is such that the condition of the flexural vibration at the joint between the inertial mass portion 4 and the flexural vibration portion 5 satisfies the sliding support condition, and the flexure at the predetermined frequency including the welding tool 6 or the suction tube mounting portion 7. Set the length to resonate. The order of the flexural vibration does not necessarily have to be the primary resonance, and an appropriate order can be selected from the entire configuration from the joining system. However, the static flexure generated by the pressing force applied at the time of joining is sufficiently large. It is necessary to consider that a small and good bending vibration can be excited. Desirably, the aspect of the flexural vibration dimension and the length dimension is set to one or more. In FIG. 1, the flexural vibration section 5 on the welding tool side has a function of amplifying the flexural vibration amplitude at the distal end and is configured to have an amplitude expansion factor as needed. If it is not necessary to amplify the amplitude, a uniform sectional shape may be used. Longitudinal vibration transmission unit 3
Can be set to a size at which the resonance including the inertial mass portion and the flexural vibration portion as a whole is １ ／ wavelength resonance or an odd multiple thereof, but is applied at the time of bonding. Select a dimension that can sufficiently reduce the static deflection generated by the pressing force. It is desirable that the dimension in the direction perpendicular to the longitudinal vibration direction is set to 波長 wavelength or less, preferably １ ／ or less. In FIG. 1, the longitudinal vibration transmitting unit 3
Of the inertial mass part 4 has a function of amplifying the longitudinal vibration amplitude of the inertial mass part 4, and the amplitude expansion rate may be set as necessary. If it is not necessary to amplify the amplitude, a uniform sectional shape may be used. The inertial mass unit 4 is driven by the longitudinal vibration transmitting unit 3 to longitudinally vibrate, and excites the flexural vibration to the flexural vibration unit 5. As a result, deformation occurs during operation. This deformation causes a shift in the resonance frequency of the flexural vibrating section 5 and causes deterioration of the vibration characteristics of the ultrasonic vibrator. Therefore, the flexural vibration of the inertial mass section 4 in the flexural vibration direction is sufficiently controlled so as to suppress this deformation. The rigidity is set sufficiently higher than the flexural rigidity of the flexural vibrating section 5, and ideally 100 times or more. In the configuration of FIG. 1, since the longitudinal vibration transmitting unit 3 supports the front surface of the inertial mass unit 4, the bending rigidity of 100 times or more can be realized. The coupling portion 8 for coupling with the main body device is disposed at a node of the longitudinal vibration of the longitudinal vibration transmitting portion 3 and has a structure extending in a direction perpendicular to the direction of the pressing force applied during joining and the longitudinal vibration direction. . A vibration mitigation mechanism 9 that is long in the pressure direction and short in the direction perpendicular to the direction in which the pressure is applied and the direction of the vertical vibration is provided in the immediate vicinity of the joint with the vertical vibration transmission unit 3. Further, a through hole 10 is provided outside the vibration damping mechanism 9 to allow a bolt or the like to pass therethrough for coupling with the main body device. Coupling part 8
Are provided on both sides of the longitudinal vibration transmitting section 3, and the portion outside the vibration mitigation mechanism 9 is set to a size having torsional rigidity for suppressing torsion that adversely affects the joining due to the pressing force at the time of joining to a sufficient level. A fastening structure such as a screw is manufactured by machining on the coupling side of the longitudinal vibration transmitting unit 3 for coupling with the ultrasonic vibrator 2, and the ultrasonic vibration 2 is fastened to the ultrasonic vibrator 2 with an appropriate tightening torque. The body 1 is manufactured. Apart from these, the joining tool 6 and, if necessary, the tube mounting portion 7
Is manufactured using electric discharge machining or machining, and is coupled to the flexural vibration section 5 of the ultrasonic vibrator 1. Figure 2 shows the joining tool 6
FIG. 4 is a cross-sectional view of a distal end portion of the flexural vibration section 5 used for joining, showing a mounting structure of the flexural vibration section 5. FIG.
In the figure, 11 is a through hole for suction inside the bending vibration part, 12 is a through hole for chip suction inside the joining tool, 13
Is a screw hole for fixing the joining tool, 14 is a fixing screw, 15 is a fitting groove for determining the orientation of the joining tool, and 16 is a chip suction surface. In the configuration shown in FIG. 2, the chip suction surface 16 is processed into an appropriate shape depending on the size and shape of the chip to be joined. For example, in the case of a rectangular chip, it is processed into a rectangle having the same size or a slightly larger shape as the chip. In order to determine the direction of the suction surface of the chip, the joining tool 15 is provided with a fitting groove 15 which is machined linearly, for example, perpendicularly to the cross section of FIG. 2, and the joining tool 6 has a fitting groove. A structure that determines the fit direction,
For example, a cylindrical structure that partially forms a fitting structure inside the through hole 11 having a circular cross section is formed. Also,
The flexural vibration section 5 is provided with a fixing screw hole 13 and a fixing screw 14 is inserted therein. The joining tool 6 is inserted into the flexural vibration part 5 as shown in FIG.
Is determined by adjusting the fixing screw. In order not to have a significant effect on the flexural vibration of the flexural vibration section 5, the position where the fixing screw hole 13 is provided is set on the distal end side from the joint position of the flexural vibration closer to the joint surface of the flexural vibration section 5, In addition, the dimension of a portion of the joining tool 6 that is inserted into the through hole 11 for fixing is also set so as to be smaller than the above-described joint position. In addition to the configuration shown in FIG. 2, for example, when the suction surface 16 of the joining tool 6 is circular and has no direction, a screw structure is provided on the tip side of the through hole 11 and the insertion portion of the joining tool 6. A method may be considered in which the joining tool 6 is rotated and inserted into the through hole 11 and fastened by the screw structure. In that case, it is convenient to provide a D-cut structure or the like in a part of the joining tool 6 so that the fastening can be performed well. FIG. 3 is a cross-sectional view showing the connection between the connecting portion 8 and the main body device. In FIG. 3, reference numeral 16 denotes a bracket having a coupling function with the main body device, reference numeral 17 denotes a fixing bolt, and reference numeral 18 denotes a slit in the vibration damping mechanism 9. FIG. 4 is a schematic diagram showing the operation of the relaxation mechanism during vibration. FIG.
Numeral 19 indicates the state of deformation in the lateral direction during the operation of the vibration damping mechanism 9. As shown in FIG. 3, the vibration damping mechanism 9 according to the first embodiment of the present invention is constituted by a crank having a slit structure 18. The coupling part 9 is arranged at a node of the longitudinal vibration of the longitudinal vibration transmitting part 3. During the operation of the ultrasonic vibrator 1, the coupling portion 9 hardly vibrates in the longitudinal vibration direction, but the vibration in the direction orthogonal to the longitudinal vibration direction as shown in FIG. 4 due to the Poisson's ratio of the material of the longitudinal vibration transmitting portion. Get excited. At this time, the vibration mitigation mechanism 9 is deformed as shown by a lateral deformation 19 in FIG. 4 to reduce the vibration and suppress the leakage of the vibration to the coupling portion 8. The cut depth of the slit 18 and the coupling width with the longitudinal vibration transmitting portion are such that the natural frequency of the lowest mode as the crank structure of the vibration damping mechanism 9 is sufficiently, preferably, twice as high as the resonance frequency of the ultrasonic vibrator 1. The dimensions of each part are set so as to be higher. Further, the thickness of the coupling portion 8 is
It is necessary to set a dimension that can secure rigidity that does not easily cause deformation due to a shearing force or a moment applied to the joint, and desirably, the depth of the slit 18 is set to half or more of the joint 8. It is desirable to set so that FIG. 5 is a diagram showing an operation at the time of joining the ultrasonic vibrator 1. In FIG. 5, reference numeral 20 denotes a pressing force applied from a main body device (not shown) via the bracket 16, 21 denotes a reaction force generated on the joint surface, 22 denotes a longitudinal vibration excited by the ultrasonic vibrator 2, and 23 denotes a pressing force. A moment generated at the joint by the pressure 20 and the reaction force 21; 24, a flip chip to be joined; 25, a mounting board; 26, a flexural vibration distribution in the flexural vibration section 5 for joining;
7 is a flexural vibration distribution in the flexural vibrating section 5 not performing the joining, and 28 is the flexural vibrating section 5 performing the joining and the inertial mass section 4.
The shear force generated at the joint surface between the flexural vibrating portion 5 and the inertial mass portion 4 that do not perform joining, and the shear force 30 generated between the flip chip 24 and the joining tool 6 during joining. Shows the frictional force that occurs. As shown in FIG. 5, a pressing force of 2
When 0 is applied, a reaction force 21 is generated, and as a result, a coupling moment indicated by 23 is generated in the coupling portion 8. At this time, the ultrasonic vibrator 1 is deformed though it is minute. In particular, the torsion generated in the coupling portion 8 and the vibration damping mechanism 9 deteriorates the parallelism of the flip chip 24 and the mounting substrate 25 to be bonded to the bonding tool 6, and thus causes deterioration of bonding performance. Since the connecting portion 9 in the first embodiment of the present invention is set to have a thickness that secures sufficient torsional rigidity as described above, deformation due to the connecting portion moment mainly occurs in the vibration damping mechanism 9. FIG. 6 is a schematic diagram showing a torsional deformation generated in the vibration damping mechanism 9 at the time of pressurization, and is a perspective view of the longitudinal vibration transmitting unit 3 as viewed from the side. 6, reference numeral 31 denotes a coupling surface on the coupling portion 8 side of the vibration damping mechanism 9 having a crank structure, 32 denotes a coupling surface on the longitudinal vibration transmitting portion 3 side, and 33 denotes a torsional deformation of the longitudinal vibration transmitting portion 3 caused by a pressing force. Is shown. The torsional deformation due to the connecting portion moment 23 in the first embodiment of the present invention is concentrated on the connecting portion of the vibration damping mechanism 9 having the lowest torsional rigidity. The magnitude of the torsional deformation is determined by the torsional rigidity as a physical property value determined by the material and shape of the structure and the length of the structure in the torsion axis direction. In the first embodiment of the present invention, the length in the torsion axis direction of the connecting portion at both ends of the vibration damping mechanism 9 can be set by the slit width for forming the crank structure. Therefore, by setting the slit width as narrow as possible, the torsional deformation generated by the coupling moment 23 can be suppressed to a range that does not cause deterioration of the joining performance. As shown in FIGS. 4 and 6, the vibration damping mechanism 9 reduces the vibration with the crank structure against the lateral vibration excited by the longitudinal vibration transmitting unit 3 and, on the surface orthogonal to the above-mentioned lateral vibration. It has a structure that can sufficiently suppress torsional deformation with respect to the generated joint moment, suppresses the vibration leakage to the joint 9 due to the lateral vibration, suppresses the occurrence of parasitic resonance, etc., and affects the joint performance. By suppressing the rotation of the ultrasonic vibrating body 1 around the joint 9, the parallelism between the joining tool 6 and the work can be maintained, and good joining can be performed. Further, considering the operation of the ultrasonic vibrating body 1 at the time of joining, the inertial mass 4
The shearing forces 28 and 29 and a moment (not shown) are applied to the connection portion of the flexural vibration portion 5. The dimensions of the inertial mass portion 4 are set such that the deformation caused by these mechanical actions is sufficiently small. Further, a frictional force 30 is generated in the joining tool 6 by the flip chip 24 and the mounting board 25 to be joined. The frictional force 30 acts as a driving force in the direction of reducing the load on the tip when viewed from the ultrasonic vibrator 2 and increases the resonance frequency of the entire ultrasonic vibrator 1. For example, when the flexural vibrating portion used for joining and the flexural vibrating portion not used for joining have the same dimensions, the shear force 28 in the unloaded state.
And 29 are equal in magnitude and orientation, and the moments generated at the joint are balanced as a whole because they are equal in magnitude and opposite in direction. However, at the time of welding, the shear force 28 and the moment change as a reaction due to the frictional force at the connecting portion of the bending vibration portion 5 and the inertial mass portion 4 on the welding tool side as described above, and the side not used for the welding does not change. The balance between the shear force 29 and the moment of the slab is broken. These generate a couple with respect to the inertial mass. The shearing force and the moment are alternating forces synchronized with the resonance frequency of the ultrasonic vibrator 1, and have a possibility of exciting unnecessary modes such as slip and torsion in the inertial mass unit 4 and the longitudinal vibration transmitting unit 3. In the first embodiment of the present invention, as shown in FIG. 1, the shape of the flexural vibration portion 5 on the joining side and the non-joining side are different. Thus, in a state where a load is applied, the shear force 28, 2
9 and the moment can be set to be balanced. The change in the shearing force 28 and the moment at the joining portion on the joining side under a load varies depending on the dimensions of the flip chip to be joined, the state of the chip surface, the state of the mounting substrate surface, or the state of the load such as the applied pressure. Therefore, a dynamic change due to a load condition may be estimated in advance by a change in resonance frequency at the time of load through an experiment or the like, and may be fed back to the design.
Although FIG. 1 illustrates the case where there are two flexural vibrating portions, it is not necessary to have two flexural vibrating portions. For example, a configuration in which three flexural vibrating portions are provided and two are used for joining may be considered. Further, regarding the flexural vibration distribution in FIG.
Although the non-joining side is in the primary mode, the moment and the shearing force as a whole need only be balanced even if the vibration order is different. In the configuration shown in FIGS. 1 to 6 described above, the ultrasonic vibrator according to the first embodiment of the present invention realizes stable vibration characteristics even under a load, causing leakage of vibration at the coupling portion and rotational deformation of the whole. And the like, and good bonding performance can be obtained. In addition, it is possible to perform good bonding by using an ultrasonic bonding apparatus using such an ultrasonic vibrator.

As described above, according to the ultrasonic vibrator of the present invention, good vibration characteristics can be realized even under a load, and good flip chip bonding performance can be obtained. Further, by using this, it is possible to provide an ultrasonic bonding apparatus capable of performing good bonding.

[Brief description of the drawings]

FIG. 1 is a schematic view of an ultrasonic vibrator according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the tip of the bending tool according to the first embodiment of the present invention.

FIG. 3 is a sectional view of a joint according to the first embodiment of the present invention;

FIG. 4 is a characteristic diagram showing a lateral operation principle of the vibration damping mechanism according to the first embodiment of the present invention.

FIG. 5 is an operation explanatory view of the ultrasonic vibrator according to the first embodiment of the present invention.

FIG. 6 is a characteristic diagram showing an operation principle in a torsional direction of the vibration damping mechanism according to the first embodiment of the present invention.

FIG. 7 is a schematic view of a conventional ultrasonic flip chip bonding.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ultrasonic vibrator 2 Ultrasonic vibrator 3 Longitudinal vibration transmitting part 4 Inertial mass part 5 Flexural vibrating part 6 Joining tool 7 Suction tube mounting part 8 Coupling part 9 Vibration mitigation mechanism 10 Through hole 11 Suction through hole 12 Suction Through hole 13 Fixing screw hole 14 Fixing screw 15 Fitting groove 16 Bracket 17 Fixing bolt 18 Slit 19 Lateral deformation 20 Pressing force 21 Reaction force 22 Longitudinal vibration 23 Coupling moment 24 Flip chip 25 Mounting board 26 Flexural vibration distribution 27 Flexural vibration distribution 28 Shear force 29 Shear force 30 Friction force 31 Coupling surface on coupling side 32 Combination surface on longitudinal vibration transmitting part 33 Torsional deformation 101 Ultrasonic vibrator 102 Bonding part 103 Bonding tool 104 Bonding bump 105 Flip Chip 106 Mounting board 107 Vibration direction

Claims (13)

[Claims] 1. An ultrasonic transducer for generating ultrasonic longitudinal vibration, a longitudinal vibration transmitting section for transmitting ultrasonic longitudinal vibration generated by the ultrasonic transducer, and a node of vibration of the longitudinal vibration transmitting section. A coupling unit provided with the main unit, a vibration damping unit provided at a part of the coupling unit to prevent the ultrasonic vibration from leaking to the coupling unit, and a tip unit of the longitudinal vibration transmitting unit. Inertial mass portion, having a flexural vibrating portion that transmits ultrasonic waves branched from the inertial mass portion, provided at least two or more flexural vibrating portions, at least of the flexural vibrating portion
An ultrasonic vibrating body characterized in that joining is performed by ultrasonic vibration of one tip. 2. An ultrasonic transducer for generating ultrasonic longitudinal vibration, a longitudinal vibration transmitting section for transmitting ultrasonic longitudinal vibration generated by the ultrasonic transducer, and a node of vibration of the longitudinal vibration transmitting section. A coupling unit for coupling to the main unit, a vibration damping unit provided at a part of the coupling unit to prevent ultrasonic vibration from leaking to the coupling unit, and a coupling unit provided at a tip of the longitudinal vibration transmitting unit. The inertial mass part, having at least two or more flexural vibrating parts that branch off from the inertial mass part and transmit ultrasonic waves, at least one end of the flexural vibrating part is a joining surface by ultrasonic vibration. Bonding is performed, and a pressing force in a direction perpendicular to a bonding surface of the tip of the bending vibration portion is supplied from a main body device connected to the connecting portion at the time of bonding, and the pressing force and the pressing force of the connecting portion and the vibration reducing portion are Longitudinal vibration direction of longitudinal vibration transmission part Ultrasonic vibrators torsional rigidity in the axial direction perpendicular, wherein the higher than torsional rigidity of the pressure direction. 3. The ultrasonic vibrator according to claim 1, wherein the flexural rigidity of the inertial mass portion in the flexural vibration direction is at least 100 times the flexural rigidity of the flexural vibration portion. 4. The ultrasonic vibrating body according to claim 1, wherein a part or all of the vertical vibration transmitting portion has an ultrasonic longitudinal vibration expanding function. 5. The ultrasonic vibrator according to claim 1, wherein a part or all of the flexural vibrator has an ultrasonic flexural vibration expanding function. 6. The ultrasonic vibrating body according to claim 1, wherein a joining tool is provided at a tip of the flexural vibrating portion for performing the joining. 7. An ultrasonic vibrator for generating ultrasonic longitudinal vibration, a longitudinal vibration transmitting section for transmitting ultrasonic longitudinal vibration generated by the ultrasonic vibrator, and a node of vibration of the longitudinal vibration transmitting section. A coupling unit for coupling to the main unit, a vibration damping unit provided at a part of the coupling unit to prevent ultrasonic vibration from leaking to the coupling unit, and a coupling unit provided at a tip of the longitudinal vibration transmitting unit. Having an inertial mass portion, and at least two flexural vibrating portions that transmit ultrasonic waves by branching from the inertial mass portion, and at least one of the flexural vibrating portions is joined by ultrasonic vibration at a tip end thereof. And at least one of the flexural vibrators does not bond. 8. A moment generated by a shear force applied to a flexural vibrating portion and an inertial mass portion that perform joining in a state where a load is applied during joining, and a shear force applied to the inertial mass portion by a flexural vibrating portion that does not perform joining. 8. The moment generated by the balance is balanced.
The ultrasonic vibrator according to the above. 9. The flexural rigidity of the inertial mass portion in the direction of vibration of the flexural vibration portion is at least 100 times the flexural rigidity of the flexural vibration portion of the flexural vibration portion. Ultrasonic vibrator. 10. The apparatus according to claim 7, wherein a part or all of the longitudinal vibration transmitting portion has an ultrasonic longitudinal vibration expanding function.
10. The ultrasonic vibrator according to any one of items 1 to 9, above. 11. The ultrasonic vibrator according to claim 7, wherein a part or all of the flexural vibrator has an ultrasonic flexural vibration expanding function. 12. The bonding tool according to claim 7, wherein a joining tool is provided at an end of the flexural vibration portion for joining.
2. The ultrasonic vibrating body according to any one of 1. 13. An ultrasonic bonding apparatus comprising the ultrasonic vibrator according to claim 1.