JP2006263816A - Ultrasonic welding method and apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ultrasonic welding method capable of suppressing wear of a suction member that sucks and holds a tip component, and also to provide an apparatus using this method. <P>SOLUTION: Within a preset welding time, when welding of the tip component to a substrate is started, while a point of time comes for starting attenuation time, a ultrasonic generator is operated by an amplitude controller. The amplitude by ultrasonic vibration in the suction member is controlled to be smaller in proportion to the elapsed time until the time to complete the welding. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ultrasonic bonding method in which an electrode of a chip component such as an electronic component is pressed and heated on an electrode of a workpiece such as a substrate and ultrasonic vibration is applied to the bonding portion and an apparatus using the ultrasonic bonding method. .

The two bonded parts made of metal of the two members to be bonded are brought into contact with each other, and the ultrasonic wave is applied to the other member to be bonded while the one member to be bonded is held by suction. Specifically, with the start of bonding, the amplitude of the ultrasonic vibration at the bonding site is increased until a predetermined amplitude is reached. The remaining time from the time when the predetermined amplitude is reached to the end of the preset bonding time is applying ultrasonic vibration to the bonding site in a state where the amplitude of the ultrasonic vibration is kept constant (for example, Patent Documents). 1).
JP-A-8-198777

  However, the conventional method has the following problems.

  That is, when the connection part is joined while the amplitude of the ultrasonic vibration is kept constant until the ultrasonic joining is completed within a predetermined joining time, the suction member that holds and holds the member to be joined. There is a problem that the adsorbing surface is worn out in a short time. That is, the joining time is set to be longer than the average joining time or set to the maximum time in consideration of the solid difference of the members to be joined (chip parts) to be joined of the joining objects. Therefore, in the case of an object to be joined in a shorter time than these set times, the joined parts of the joined members are strongly metal-bonded at an earlier time within the joining time, and exceed the attracting force of the joined member by the attracting member. As a result, the suction surface of the suction member slides on the surface of the member to be joined and wears due to friction.

  This invention is made | formed in view of such a situation, Comprising: It aims at providing the ultrasonic bonding method and apparatus using the same which can suppress abrasion of an adsorption | suction member.

  The present invention has the following configuration in order to achieve the above object.

The first invention is an ultrasonic bonding method for applying ultrasonic vibration to both electrodes and bonding them while pressing the electrode of the chip component adsorbed and held on the adsorption member against the electrode of the work,
Of the bonding time set in advance according to the type of the chip component, the amplitude of ultrasonic vibration at the bonding portion of the electrodes is reduced after a predetermined time has elapsed.

  (Operation / Effect) According to the first invention, when both the chip component and the substrate electrode are metal-bonded within a predetermined time, the adsorption strength of the chip component by the adsorption member is weaker than the bonding strength. The suction surface of the suction member slides on the surface of the chip component and rubs. However, since the amplitude of the ultrasonic vibration is small when the suction member is rubbed, friction between the suction surface of the suction member and the surface of the chip component is suppressed. As a result, it is possible to suppress wear on the suction surface of the suction member.

  Further, transmission stress due to friction applied to the electrode mounting portion on the chip component side, which is weaker than the metal bond between the electrode of the chip component and the electrode of the substrate, is suppressed. That is, it is possible to suppress cracks that tend to occur due to transmission stress applied to the electrode mounting portion on the chip component side. As a result, it is possible to improve the bonding accuracy of chip components.

  Furthermore, since the ultrasonic vibration is continuously applied to the connection part until the joining of the two electrodes is finished even if the amplitude of the ultrasonic vibration is small, metal deformation due to pressing is promoted. Therefore, both electrodes can be joined in a shorter time than joining by pressing alone.

  The change in the amplitude of the ultrasonic vibration is, for example, decreased in proportion to the time after a predetermined time elapses in the joining time (second invention), or the time elapsed after the elapse of the predetermined time in the joining time. It is preferable to reduce the size step by step (third invention). By setting in this way, the first invention can be suitably implemented.

  According to a fourth aspect of the present invention, in the first to third aspects of the present invention, the amplitude of the ultrasonic vibration is increased in proportion to the passage of time until a predetermined time has elapsed from the start of joining the electrodes. It is preferable to go.

  (Operation / Effect) According to the fourth invention, compared to the case where the joining is started with the ultrasonic vibration having a predetermined amplitude at the same time as the joining is started, the frictional resistance due to the ultrasonic vibration applied between the chip component and the substrate is initially reduced. Can be reduced. That is, by reducing the friction between both electrodes, the transmission stress transmitted between the suction surface of the suction member and the surface of the chip component is suppressed, and wear due to the friction of the suction surface of the suction member can be suppressed. .

  According to a fifth invention, in any one of the first to fourth inventions, it is preferable that the frequency is adjusted within a predetermined frequency band in which the ultrasonic vibration is generated as the joining time elapses.

  (Operation / Effect) According to the fifth aspect of the invention, by adjusting the frequency within a predetermined frequency band for generating ultrasonic vibration, a frequency that provides the optimum ultrasonic vibration according to the electrode shape of the chip component is selected. In other words, useless slippage between the suction surface of the suction member and the surface of the chip component can be suppressed.

  According to a sixth invention, in any one of the first to fifth inventions, the ultrasonic wave vibration is applied to the joint portion between both electrodes of the workpiece and the chip component, and the joint portion is heated. preferable.

  (Operation / Effect) According to the sixth invention, the deformation of both electrodes is promoted by heating the joint portion. Therefore, the efficiency of ultrasonic bonding can be improved.

The seventh invention is an ultrasonic bonding apparatus for applying an ultrasonic vibration to both electrodes and bonding them while pressing an electrode of a chip component and an electrode of a workpiece.
First holding means for holding the chip component;
Support means for supporting the first holding means;
Ultrasonic vibration applying means for applying ultrasonic vibration to the first holding means;
Second holding means for holding the workpiece;
An elevating drive mechanism for elevating and lowering at least one of the supporting means supporting the first holding means and the second holding means;
When an ultrasonic wave is applied from the ultrasonic vibration applying unit to the first holding unit, the amplitude of the ultrasonic vibration at the joint portion between the electrode of the chip component and the workpiece is preset according to the type of the chip component. Amplitude control means for controlling so as to decrease after a predetermined time has elapsed,
It is provided with.

  (Operation / Effect) According to the seventh invention, the first holding means holds the chip component. The support means holds the first holding means. The ultrasonic vibration applying means applies ultrasonic vibration to the first holding means. The elevating drive mechanism elevates and lowers at least one of the support means supporting the first holding means and the second holding means. The amplitude control means is configured such that when the ultrasonic wave is applied from the ultrasonic vibration applying means to the first holding means, the amplitude of the ultrasonic vibration at the joining portion between the electrode of the chip component and the workpiece depends on the type of the chip component. Control is performed so as to decrease after a predetermined time has elapsed since the start of bonding.

  According to this configuration, the electrode of the chip component and the electrode of the workpiece are pressed in a heated state by raising or lowering either the support means or the second holding means. In addition, the ultrasonic vibration is applied to both the electrodes in the pressed state, and the amplitude of the ultrasonic vibration at the both electrode portions that are the connection portions is reduced after a predetermined time has elapsed. Therefore, when both electrodes of the chip component and the substrate are metal-bonded within a predetermined time, both members are suppressed from slipping due to ultrasonic vibration continuously applied on the adsorption surface of the adsorption member and the surface of the chip component. Friction is also suppressed. Therefore, the first invention can be suitably realized.

  In an eighth aspect based on the seventh aspect, the amplitude control means further controls the amplitude of the ultrasonic vibration in proportion to the passage of time until a predetermined time has elapsed from the start of joining of the electrodes. It is preferable to control so as to increase.

  (Operation and Effect) According to the eighth invention, the above-described fourth method invention can be suitably realized.

The ninth invention is the seventh or eighth invention, further comprising a frequency adjusting means for adjusting a frequency within a predetermined frequency band in which the ultrasonic vibration is generated as the joining time elapses. And

  (Operation / Effect) According to the ninth invention, the above-described fifth method invention can be suitably realized.

  In a tenth aspect of the present invention, in any one of the seventh to ninth aspects, it is preferable that the apparatus further includes a heating unit that heats a joint portion between the workpiece and the electrode of the chip component.

  (Operation and Effect) According to the tenth invention, the above-described sixth method invention can be suitably realized.

  According to the ultrasonic bonding method and the apparatus using the ultrasonic bonding method according to the present invention, when both the chip component and the substrate electrode are metal-bonded within a predetermined time, the chip component by the adsorption member is more than the bonding strength. Since the suction strength is weak, the suction surface of the suction member slides on the surface of the chip part and rubs. However, since the amplitude of the ultrasonic vibration is small when the suction member is rubbed, friction between the suction surface of the suction member and the surface of the chip component is suppressed. As a result, it is possible to suppress wear on the suction surface of the suction member.

  Further, transmission stress due to friction applied to the electrode mounting portion on the chip component side, which is weaker than the metal bond between the electrode of the chip component and the electrode of the substrate, is suppressed. That is, it is possible to suppress cracks that tend to occur due to transmission stress applied to the electrode mounting portion on the chip component side. As a result, it is possible to improve the bonding accuracy of chip components.

  Further, until the joining of both electrodes is completed, even if the amplitude of the ultrasonic vibration is small, the ultrasonic vibration is applied to the connection site, and therefore metal deformation due to pressing is promoted. Therefore, it is possible to join the electrodes in a shorter time than joining by pressing alone.

  Embodiments of the present invention will be described below with reference to the drawings. In this embodiment, a case where an electronic component with a bump is mounted on a substrate as a chip component will be described as an example. In addition, as the chip component, for example, all forms on the side to be bonded to the substrate are shown regardless of the type and size of an IC chip, a semiconductor chip, an optical element, a surface mount component, a wafer, and the like.

  Moreover, as a board | substrate, all the forms of the side joined to chip components, such as a resin substrate, a glass substrate, a film substrate, are shown, for example.

  FIG. 1 is a front view of the ultrasonic bonding apparatus according to the present embodiment.

  As shown in FIG. 1, the ultrasonic bonding apparatus according to the present embodiment includes a movable table 3 having a substrate holder 2 that holds the substrate 1 by suction, and a vertical frame 5 that is erected at the rear portion of the base 4. 6, a crimping mechanism 9 having a crimping head 8 that is mounted (bonded) to the substrate 1 by sucking and holding the chip component 7 at the tip, and the substrate 1 and the crimping head 8 held by the substrate holder 2. A camera 10 for recognizing the position of the chip component 7 to be sucked and held, a movable table 3, a pressure-bonding head 8, a pressure-bonding mechanism 9, a main controller 11 that controls driving of the camera 10, and the like are provided. The substrate holder 2 corresponds to the second holding means of the present invention.

  The movable table 3 is configured to be movable in two horizontal (X, Y) directions in the left and right and front and rear directions in the figure. Further, the substrate holder 2 provided in the movable table 3 has a suction hole (not shown) formed in the surface portion on which the substrate 1 is placed, and the suction hole is connected to a vacuum pump (not shown) through a pipe. Has been. In this embodiment, the holding of the substrate 1 in the substrate holder 2 is an adsorption type. However, the holding type is not limited to the adsorption type, and mechanical holding using a movable claw, electrostatic adsorption using static electricity, and a magnet are used. Any holding structure such as magnetic adsorption can be used.

  The crimping mechanism 9 includes a cylinder 12 fixed to the support frame 6, a main body 14 connected to a rod 13 directed vertically downward of the cylinder 12, and a crimping head 8 provided at the lower end of the main body 14. Has been. That is, the pressure bonding head 8 is configured to move up and down in conjunction with the expansion and contraction operation of the cylinder 12. The cylinder 12 corresponds to the lifting drive mechanism of the present invention.

  Further, as shown in FIG. 2, the crimping head 8 has a substantially U-shaped upside down frame 15 with a bottom surface connected to the lower part of the main body 14, and through holes formed on both side surfaces of the frame 15 on both sides. And a horn 17 that is detachably held in a state of being sandwiched between the pair of boosters 16 inside the frame 15. The frame 15 corresponds to the support means of the present invention.

  The booster 16 has a cylindrical shape with a thick central portion, and has a tapered shape in which both ends thereof taper toward the tip. In addition, the booster 16 on the left side in the figure includes an ultrasonic generator 18 including a piezoelectric element for transmitting and imparting ultrasonic vibration to the booster 16. The ultrasonic generator 18 and the booster 16, the holding portion of the booster 16 by the frame 15, and the nodes of the booster 16 and the horn 17 vibrate when they resonate due to the ultrasonic vibration applied from the ultrasonic generator 18. It is set to a nodal point where the amplitude is zero. The ultrasonic generator 18 corresponds to the ultrasonic generator of the present invention.

  The horn 17 is a thick plate-like object, and through holes are formed so as to form a lattice shape in front and rear when viewed from the front. Further, a suction member 19 made of a convex portion is provided at the center of the lower surface, and a through hole 20 connected to a vacuum pump (not shown) is formed. Moreover, a hole is formed in the lattice portion in the middle of the height direction, and the ceramic heater 22 is inserted into the hole. The attachment portion of the ceramic heater 22 is also set to a nodal point. The suction member 19 corresponds to the first holding means of the present invention.

  Further, the adsorption member 19 is coated with fluorine to suppress friction with the surface of the chip component 7 when ultrasonic vibration is applied and the chip component 7 is bonded to the substrate 1. In addition, it exists in the position where the vibration amplitude transmitted from the supersonic generator 18 via the booster 16 becomes the maximum.

  Returning to FIG. 1, the camera 10 is movable in two horizontal axes (X, Y) and up and down (Z). In addition, a lens barrel 23 that advances and retracts toward the crimping head is provided. Further, the camera 10 is moved forward in the X-axis direction and is positioned between the chip component 7 and the substrate 1 that are sucked and held by the sucking member 19 of the horn 17. In this state, the positions of the chip component 7 and the substrate 1 are recognized and observed, and the observation result is transmitted to the main control unit 11. As a means for recognizing and observing the positions of both members, all forms other than the camera that can recognize the positions of the substrate 1 and the chip component 7 are applicable regardless of the types of infrared cameras, sensors, and the like.

  The main control unit 11 selects a bonding condition according to the types of the substrate 1 and the chip component 7 to be bonded set and input from the operation unit 24 from a pattern table (not shown), and transmits the selected pattern to the amplitude control unit 25. . The main control unit 11 also comprehensively controls driving of the movable table 3, the cylinder 12, the camera 10, and the like based on information set and input from the operation unit 24.

  The amplitude control unit 25 controls the amplitude of the ultrasonic vibration in the adsorption member 19 of the horn 17 that resonates by the ultrasonic vibration generated from the ultrasonic generator 18. For example, as shown in FIG. 3, when the joining time of the chip component 7 is 1 second, the amplitude at the adsorption member 19 of the horn 17 is maintained to be the maximum from the start of joining until 0.5 seconds. Generates ultrasonic waves so that the amplitude starts at the time when 0.5 second has elapsed so that the amplitude becomes zero when the end time reaches 1 second, and the amplitude decreases in proportion to the passage of time from that time. The device 18 is operated. The attenuation start time of the amplitude of the ultrasonic vibration varies depending on the type of the chip component 7, but is set at a time when 10 to 50% has elapsed from the start of the joining in the predetermined joining start time. The amplitude control unit 25 corresponds to the amplitude control means of the present invention.

  Next, the operation of bonding the chip component 7 to the substrate 1 using the above-described embodiment apparatus will be described based on the flowchart shown in FIG.

  First, the types of the substrate 1 and the chip component 7 to be joined are selected and input from the operation unit 24, and various initial conditions such as the joining time are set (step S1).

  When the initial setting is completed, the substrate 1 is placed and held on the substrate holder 2, and the chip component 7 is sucked and held by the suction member 19 at the tip of the horn 17, and the joining process is started (step S2).

  When the joining process starts, the camera 10 operates under the control of the main control unit 11. The camera 10 advances the lens barrel 23 to acquire image data of the substrate 1 and the chip component 7 and transmits the data to the main control unit 11. Based on the received image data, the main control unit 11 obtains a relative positional deviation between the substrate 1 and the chip component 7 by calculation, and moves the movable table 3 in the X and Y directions based on the obtained detection result. The misalignment is corrected (step S3).

  When the positional deviation correction is completed, the cylinder 12 is operated based on the control of the main control unit 11, and the crimping head 8 is lowered to a predetermined position to press the chip component 7 against the substrate 1. At the same time, the horn 17 is heated to a predetermined temperature by the ceramic heater 22 and the ultrasonic generator 18 is driven to start applying ultrasonic vibration to the horn 17 (step S4).

  As the joining starts, the amplitude control unit 25 counts whether or not a preset attenuation start time has been reached. When the attenuation start time is reached, the amplitude of the horn 17 due to ultrasonic vibration is reduced as shown in FIG. 3 based on a preselected pattern (step S5).

  When the timer count by the amplitude controller 25 reaches a predetermined time (step S6), the application of ultrasonic vibration from the ultrasonic generator 18 to the horn 17 is stopped, the pressure-bonding head 8 is raised, and the substrate 1 is taken out. The main joining process ends.

  As described above, when the chip component 7 is bonded to the substrate 1 by applying ultrasonic vibration to the horn 17, the time after a predetermined time elapses in the bonding time preset for each of the chip component 7 and the substrate 1. By reducing the amplitude so that the amplitude becomes zero in proportion to the passage of time, the friction between the surface of the suction member 19 of the horn 17 and the surface of the chip component 7 is reduced. As a result, the suction member 19 The wear of the adsorption surface is also suppressed. That is, even if both the electrodes 30 and 31 of the chip component 7 and the substrate 1 are firmly metal-bonded, the amplitude decreases, so that the friction between the suction member 19 and the chip component 7 is reduced.

  Further, since the transmission stress due to friction applied to the electrode mounting portion on the chip component side, which is weaker than the metal bond between the electrode 31 of the chip component 7 and the electrode 30 of the substrate 1, is suppressed, cracks that tend to occur in the portion are suppressed. be able to. As a result, the joining accuracy of the chip component 7 can be improved.

  Further, until the joining of the electrodes 30 and 31 is completed, even if the amplitude is small, ultrasonic vibration is continuously applied to the connection site, so that metal deformation due to pressing and heating is promoted. It is done. Therefore, both electrodes 30 and 31 can be joined in a shorter time than joining by only pressing and heating.

  The present invention can also be implemented in the following forms.

  (1) In the above embodiment, the amplitude is linearly reduced in proportion to the elapsed time from the decay start time, but is not limited to this form, and is gradually reduced as time passes. You may control. Even if the amplitude is controlled in this way, the same effect as in the above-described embodiment can be obtained.

  (2) In the above embodiment, the amplitude of the bonded portion is maximized simultaneously with the start of bonding. However, as shown in FIG. 5, the amplitude due to ultrasonic vibration is increased from the bonding start to the attenuation start time. You may control so that it may go. According to this configuration, it is possible to reduce frictional resistance due to ultrasonic vibration initially applied between the chip component 7 and the electrode of the substrate 1 as compared with the case where the bonding is started at a constant amplitude all the time at the start of the bonding. Therefore, by reducing the friction between the two electrodes, the transmission stress transmitted between the suction surface of the suction member 19 and the surface of the chip component 7 is suppressed, and wear due to the friction of the suction surface of the suction member 19 is suppressed. be able to.

  (3) In the above embodiment, the frequency at which the horn 17 generates ultrasonic vibrations is kept constant, but the frequency may be adjusted with a predetermined frequency bandwidth that generates ultrasonic vibrations. According to this configuration, it is possible to select an optimum frequency of ultrasonic vibration according to the electrode shape and the like of the chip component 7, and to suppress unnecessary slippage between the suction surface of the suction member 19 and the surface of the chip component 7. can do.

It is a front view which shows the whole ultrasonic bonding apparatus which concerns on an Example. It is a front view which shows the principal part structure of a horn. It is a figure which shows the change of an amplitude. It is a flowchart explaining operation | movement of an Example apparatus. It is a figure which shows the change of the amplitude which concerns on a modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Board | substrate 2 ... Board | substrate holder 7 ... Chip component 8 ... Crimp head 11 ... Main control part 17 ... Horn 18 ... Ultrasonic generator 19 ... Adsorption member 25 ... Amplitude control part 30 ... Electrode (board | substrate)
31 ... Electrode (chip component)

Claims (10)

An ultrasonic bonding method for bonding by applying ultrasonic vibration to both electrodes while pressing the electrode of the chip component adsorbed and held by the adsorption member against the electrode of the work,
An ultrasonic bonding method characterized by reducing the amplitude of ultrasonic vibration at a bonding portion of both electrodes after a predetermined time has elapsed among predetermined bonding times set in accordance with the type of the chip component. The ultrasonic bonding method according to claim 1,
The change in the amplitude of the ultrasonic vibration is reduced in proportion to the time after a predetermined time elapses in the bonding time. The ultrasonic bonding method according to claim 1,
The change in the amplitude of the ultrasonic vibration is gradually reduced according to the elapsed time after a predetermined time has elapsed in the bonding time. In the ultrasonic bonding method according to any one of claims 1 to 3,
Furthermore, the ultrasonic bonding method is characterized in that the amplitude of ultrasonic vibration is increased in proportion to the elapse of time until a predetermined time elapses from the start of electrode bonding in the bonding time. In the ultrasonic joining method according to any one of claims 1 to 4,
A frequency is adjusted within a predetermined frequency band for generating the ultrasonic vibration as the bonding time elapses. In the ultrasonic bonding method according to any one of claims 1 to 5,
An ultrasonic bonding method comprising heating the bonding portion while ultrasonic vibration is applied to the bonding portion between both electrodes of the workpiece and the chip component. In the ultrasonic bonding apparatus that applies ultrasonic vibration to both electrodes and bonds them while pressing the electrode of the chip component and the electrode of the workpiece,
First holding means for holding the chip component;
Support means for supporting the first holding means;
Ultrasonic vibration applying means for applying ultrasonic vibration to the first holding means;
Second holding means for holding the workpiece;
An elevating drive mechanism for elevating and lowering at least one of the supporting means supporting the first holding means and the second holding means;
When an ultrasonic wave is applied from the ultrasonic vibration applying unit to the first holding unit, the amplitude of the ultrasonic vibration at the joint portion between the electrode of the chip component and the workpiece is preset according to the type of the chip component. Amplitude control means for controlling so as to decrease after a predetermined time has elapsed,
An ultrasonic bonding apparatus comprising: The ultrasonic bonding apparatus according to claim 7,
The amplitude control means further controls to increase the amplitude of the ultrasonic vibration in proportion to the elapse of time until a predetermined time elapses from the start of electrode joining in the joining time. Ultrasonic bonding device. The ultrasonic bonding apparatus according to claim 7 or 8,
The ultrasonic bonding apparatus further comprises frequency adjusting means for adjusting a frequency within a predetermined frequency band for generating the ultrasonic vibration as the bonding time elapses. The ultrasonic bonding apparatus according to any one of claims 7 to 9,
Furthermore, the ultrasonic joining apparatus characterized by the above-mentioned. The heating means which heats the junction part of both the electrode of the said workpiece | work and the said chip component.

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