JP7407475B2 - Ultrasonic bonding method - Google Patents

Description

The present invention relates to an ultrasonic bonding method for bonding metal, plastic, and other workpieces using ultrasonic vibration.

Conventionally, welding technology has been used to join plastics used in food packs and the like, and metals such as battery parts. Moreover, as one of the welding techniques, ultrasonic bonding is known, in which the tip of a bonding tip is ultrasonically vibrated and pressure is repeatedly applied to the objects to be bonded.

The electrode catheter of Patent Document 1 has an electrode with excellent contrast performance (visibility in X-ray images, etc.) so that the metal ring inserted into the body can be visually recognized in X-ray images, etc. Welding is used to attach the electrodes.

In the electrode section, the resin coating is peeled off from the tip of the lead wire to expose the metal core wire, and the metal core wire is resistance welded to the inner peripheral surface of the metal ring. Thereby, a lead wire is connected to each of the nine metal rings (Patent Document 1/Paragraph 0056, FIG. 5).

Japanese Patent Application Publication No. 2012-034852

However, in Patent Document 1, since welding is performed in a minute area, there is a problem that the joining position is difficult to visually recognize and reliable joining is difficult.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an ultrasonic bonding method that can easily perform localized bonding that is difficult to visually recognize.

The first invention vibrates the bonding tip by ultrasonic vibration that is a combination of a vibration component in a first direction perpendicular to the direction in which the bonding tip presses and a vibration component in a second direction orthogonal to the first direction. An ultrasonic welding method for joining workpieces by inserting a cylindrical or cylindrical anvil having a smaller diameter than the inner diameter of the cylindrical workpiece into the inside of the cylindrical workpiece; a step of inserting a linear workpiece having a diameter smaller than the gap into the gap between the shaped workpiece and the anvil, and moving the tip of the linear workpiece to a joining position on the inner peripheral surface of the cylindrical workpiece; applying the ultrasonic vibration by bringing the welding tip into contact with a position on the outer circumferential surface of the cylindrical workpiece corresponding to the welding position, the linear workpiece being placed along the outer circumference surface of the anvil; It is also characterized in that a guiding groove in the longitudinal direction is provided for guiding to the joining position.

In the ultrasonic bonding method of the present invention, the tip of the bonding tip is pressed against the workpiece, and ultrasonic vibration (compound vibrate) to vibrate the bonding tip. In this way, bonding is performed while removing impurities from the surface of the workpiece.

First, a cylindrical or cylindrical anvil is inserted inside a cylindrical workpiece, and then a linear workpiece is inserted into the gap between them. After that, it is necessary to move the tip of the linear workpiece to the joining position on the inner circumferential surface of the cylindrical workpiece, but since a guide groove is provided on the outer circumferential surface of the anvil, the linear workpiece must be moved into the guide groove. along the same line and guide it to the joining position. Further, a joining tip is brought into contact with the outer circumferential surface of the cylindrical workpiece, and ultrasonic vibration is applied to join the workpiece. Thereby, local joining that is difficult to visually recognize can be easily performed.

In the ultrasonic bonding method of the first invention, it is preferable that the guide groove is formed so that the groove becomes shallower as it approaches the end of the anvil.

When the linear workpiece is moved along the guide groove of the present invention with its tip end to the joining position, the position of the linear workpiece becomes higher at the joining position, and the gap between the linear workpiece and the cylindrical workpiece increases. decreases. Thereby, the cylindrical workpiece and the linear workpiece can be reliably joined.

Moreover, in the ultrasonic bonding method of the first invention, it is preferable to include a step of pressing the cylindrical workpiece from both ends in the longitudinal direction.

By pressing and restraining the cylindrical workpiece from both ends in the longitudinal direction, it is possible to prevent rotation of the cylindrical workpiece during welding and improve welding quality.

The second invention vibrates the bonding tip by ultrasonic vibration that is a combination of a vibration component in a first direction perpendicular to the direction in which the bonding tip presses and a vibration component in a second direction orthogonal to the first direction. An ultrasonic welding method for joining workpieces by inserting into the inside of a cylindrical workpiece a protrusion having a diameter smaller than that of the cylindrical workpiece, which the welding tip has; a step of inserting a linear workpiece into the inside of the linear workpiece and moving the tip of the linear workpiece to a joining position on the inner peripheral surface of the cylindrical workpiece; moving the protrusion to the joining position; applying ultrasonic vibration, and in the step of inserting the linear work, the linear work is fixed to a guide block, and the relative position of the guide block with respect to the cylindrical work is changed. shall be.

In the ultrasonic bonding method of the present invention, the bonding tip has a protrusion smaller in diameter than the cylindrical workpiece, and the protrusion is inserted into the cylindrical workpiece. Thereafter, a linear workpiece is inserted into the cylindrical workpiece and moved to a joining position. At this time, the linear workpiece is fixed to the guide block and the relative position of the guide block is changed so that the linear workpiece reaches the joining position. Thereafter, the protrusion of the bonding chip is moved to the bonding position, and ultrasonic vibration is applied to bond the chips. Thereby, local joining that cannot be visually recognized can be easily performed.

In the ultrasonic bonding method of the second invention, it is preferable that the protrusion is removable from the bonding chip.

According to this configuration, since the protrusion can be attached to an existing bonding chip and used, the shape of the protrusion can be changed depending on the bonding purpose.

1 is a diagram illustrating the overall configuration of an ultrasonic bonding apparatus according to an embodiment of the present invention. FIG. 1 is a schematic diagram (cross-sectional view) illustrating the ultrasonic bonding method of the first embodiment. (a) A sectional view of the vicinity of the joining position seen from the front side. (b) Side view of the anvil. 1 is a flowchart of the ultrasonic bonding method of the first embodiment. FIG. 6 is a schematic diagram (cross-sectional view) illustrating the ultrasonic bonding method of the second embodiment. Enlarged view of the horn tip. 2 is a flowchart of an ultrasonic bonding method according to a second embodiment.

Embodiments of the ultrasonic bonding apparatus of the present invention will be described below with reference to the drawings.

[First embodiment]
First, with reference to FIG. 1, the overall configuration of an ultrasonic bonding apparatus 1 used in the ultrasonic bonding method of the present invention will be described. The ultrasonic welding apparatus 1 is an apparatus that welds (welds) objects to be welded (workpieces) such as metal plates using ultrasonic complex vibrations, which will be described later. The ultrasonic bonding apparatus 1 is mainly used for bonding electrodes of lithium ion batteries and semiconductor devices, and metals of the same or different types.

The ultrasonic bonding apparatus 1 includes an ultrasonic vibrator 2, an ultrasonic expansion horn 3, an ultrasonic LT (Langevin type) horn 4, a horn tip 6, and an anvil 7. Further, the oscillation device 8, the pressure device 10, the sensor 12, the control device 13, and the display device 14 are also part of the ultrasonic bonding device 1.

When a power supply voltage is applied to the oscillator 8 from a power source (not shown), a voltage signal is transmitted to the + and - electrodes of the ultrasonic vibrator 2, causing the ultrasonic vibrator 2 to vibrate and generate ultrasonic vibrations (approximately 20 KHz). occurs. The ultrasonic vibrations generated by the ultrasonic vibrator 2 are transmitted to a cylindrical ultrasonic amplifying horn 3 attached to one end of the ultrasonic vibrator 2, and the vibration amplitude is expanded. Further, the ultrasonic vibrations are transmitted to a cylindrical ultrasonic LT horn 4 attached to one end of the ultrasonic amplifying horn 3 (the end on the side where the ultrasonic vibrator 2 is not provided).

Up to this point, the ultrasonic vibrations generated by the ultrasonic transducer 2 have been transmitted in the longitudinal direction of the ultrasonic amplifying horn 3 and the ultrasonic LT horn 4 (longitudinal vibration of the ultrasonic wave). The plurality of diagonal slits 4a generate vibration components that are converted from longitudinal vibrations to transverse vibrations. The ultrasonic vibration (complex vibration) is generated by a horn tip 6 (the "bonding tip" of the present invention) screwed to one end of the ultrasonic LT horn 4 (the end on the side where the ultrasonic amplifying horn 3 is not attached). equivalent).

The horn tip 6 consists of a truncated conical base portion 6a and a tip portion 6b that comes into contact with the workpiece during welding. That is, by adjusting the phase of ultrasonic vibration with the oscillator 8, compound vibration (for example, elliptical vibration) is generated at one end of the ultrasonic LT horn 4, and the tip 6b of the horn tip 6 moves the surface of the workpiece in an elliptical shape. It vibrates in an orbit. This vibration eliminates impurities on the surface of the workpiece and further promotes plastic deformation of the surface of the workpiece. Note that the horn tip 6 has various shapes and can be used interchangeably depending on the type of workpiece.

A supplementary note about compound vibration is that when the tip 6b (end surface 6c) of the horn tip 6 presses the workpiece, a vibration component is generated in a first direction perpendicular to the direction of the pressing, and a second direction perpendicular to the first direction. It is a vibration that is a combination of the vibration components of . If the vibration component in the first direction and the vibration component in the second direction are 1:1, it will be circular vibration, and if it is 2:1, it will be elliptical vibration.

Further, a highly rigid pressurizing block (not shown) is in contact with the flange portion 3a of the ultrasonic amplification horn 3. Therefore, the pressure device 10 can be controlled by the control device 13, and the ultrasonic bonding device 1 can be moved in the vertical direction via the pressure block that moves up and down.

In this embodiment, a linear workpiece Wb, which is a thin metal wire, is joined to the inner peripheral surface of a cylindrical metal workpiece Wa. For this reason, a cylindrical or cylindrical anvil 7 having a smaller diameter than the inner diameter of the cylindrical workpiece Wa is used.

Here, the linear workpiece Wb has a diameter smaller than the gap between the cylindrical workpiece Wa and the anvil 7, and the linear workpiece Wb is inserted from the end of the cylindrical workpiece Wa, and its tip is moved to the joining position. . Then, the tip 6b of the horn tip 6 is brought into contact with the outer peripheral surface of the cylindrical workpiece Wa at the joining position, and static pressure (200 to 800 N during joining) is applied.

The ultrasonic bonding apparatus 1 includes a sensor (stroke sensor) 12 that detects the displacement of the pressurizing block, and the sensor 12 acquires the pushing amount of the workpiece (cylindrical workpiece Wa) of the horn tip 6. Further, the sensor 12 feeds back the vertical coordinate change of the horn tip 6 during welding to the control device 13 (the broken line is a feedback signal), so that the pushing amount is kept constant. For this reason, the pressurizing device 10 uses an actuator with a fast response speed.

The amount of pushing can be set by the operator from the display device 14. Further, a pressure sensor may be provided in addition to the sensor 12 to control the static pressure to be kept constant. In this way, when welding workpieces, welding (solid phase welding) is reliably promoted by applying compound vibration while adjusting the pushing amount and static pressure.

To add more information about solid phase bonding, for example, the surfaces of metal atoms are covered with oil or an oxide film, which prevents the atoms from coming close to each other. In ultrasonic bonding, ultrasonic vibrations are applied to metal to generate strong frictional force on the metal surface. As a result, oxide films and the like on the metal surface are removed, and clean and activated metal atoms appear on the bonding surface.

In this state, by further applying ultrasonic vibration to the metal surface of the workpiece (the outer peripheral surface of the cylindrical workpiece Wa), the temperature rise due to frictional heat activates the movement of atoms, and mutual attraction between atoms is generated. A state of solid phase junction is created.

Next, a specific example of the first embodiment (first ultrasonic bonding method) of the present invention will be described with reference to FIGS. 2A and 2B.

First, FIG. 2A shows a cross-sectional view near the joining position X. The cylindrical workpiece Wa is a metal pipe with a diameter of a and a wall thickness of b (inner diameter a-2b). Note that the diameter a is approximately 2.0 to 3.0 [mm], and the wall thickness b is approximately 0.05 to 0.08 [mm]. Further, the linear workpiece Wb is a thin metal wire with a diameter d (approximately 0.05 to 0.10 [mm]), and the coating resin is peeled off at the tip to expose the core wire.

Further, the anvil 7 has a cylindrical shape with a diameter of c (c<a-2b), and when inserted into the inside of the cylindrical workpiece Wa, it becomes a pedestal during joining. Since the gap (=a-2b-c) between the cylindrical workpiece Wa and the anvil 7 is about 0.20 to 0.25 [mm], the linear workpiece Wb is passed through this gap, and the linear workpiece Wb is Make sure that the tip is set at joining position X.

A guide groove 7a for guiding the linear workpiece Wb is formed on the outer peripheral surface of the anvil 7 (a position facing the joining position X) (see FIG. 2B(b)). The linear workpiece Wb is moved along the guide groove 7a to the joining position X, or the leading end of the linear workpiece Wb reaches the joining position X while the linear workpiece Wb is fitted into the guiding groove 7a. Move the anvil 7 so that

Thereafter, the tip of the horn tip 6 is brought into contact with the outer circumferential surface of the cylindrical workpiece Wa at the joining position X, and ultrasonic vibration is applied to the workpiece Wa to join the workpiece. Note that the amplitude of the ultrasonic vibration is approximately 5.0 [μm] at maximum. Although the worker cannot visually recognize the joint from the outside, the linear workpiece Wb can be reliably joined to the inner peripheral surface of the cylindrical workpiece Wa.

FIG. 2B(a) is a sectional view of the vicinity of the joining position X seen from the front side. As shown in the figure, the linear workpiece Wb is at least partially fitted into the guide groove 7a, and is set on the inner circumferential surface of the cylindrical workpiece Wa at the joining position X with almost no gap. Note that the tip portion 6b of the horn tip 6 is located outside the joining position X.

FIG. 2B(b) is a diagram of only the anvil 7 viewed from the side. The anvil 7 is formed with a two-step groove that becomes shallower toward the left end, consisting of a guide groove 7a and a shallowest portion 7b. If the left end of the anvil 7 is moved to the vicinity of the welding position , the linear workpiece Wb comes into contact with the inner peripheral surface of the cylindrical workpiece Wa).

When the linear workpiece Wb is inserted from the right side in the figure, the tip (covering resin) of the linear workpiece Wb is caught and stopped at the shallowest portion 7b. The shallowest portion 7b has a depth such that approximately 70% of the diameter d of the linear workpiece Wb protrudes above the anvil 7. Note that the anvil 7 may have a cylindrical shape as long as the anvil 7 has a wall thickness sufficient to form the guide groove 7a and the shallowest portion 7b.

Alternatively, the anvil 7 with the linear workpiece Wb fitted into the guide groove 7a (the shallowest portion 7b) may be moved to the joining position X (toward the left in the figure). Also by this method, the cylindrical workpiece Wa and the linear workpiece Wb can be reliably joined.

Next, a flowchart of the first ultrasonic bonding method will be described with reference to FIG.

First, the cylindrical workpiece Wa is fixed (step S01). Specifically, the cylindrical workpiece Wa is pressed and fixed from both ends. Thereby, no positional shift occurs when moving the linear workpiece Wb to the joining position X, and furthermore, it is possible to prevent rotation of the cylindrical workpiece Wa during joining.

Next, the anvil 7 is inserted into the cylindrical workpiece Wa and moved to the joining position X (step S02), and the linear workpiece Wb is inserted along the guide groove 7a of the anvil 7 (step S03). Due to the groove shape of the guide groove 7a, the linear workpiece Wb substantially comes into contact with the inner circumferential surface of the cylindrical workpiece Wa at the joining position X.

Next, the horn tip 6 is set so that the tip 6b is located above the joining position X (the outer peripheral surface of the cylindrical workpiece Wa) (step S04). It is preferable to move the horn tip 6 reliably onto the joining position X by positioning it using an XY table or the like.

Finally, the horn tip 6 is brought into contact and ultrasonic vibration is applied to join the workpieces (step S05). Thereby, the operator can join the linear workpiece Wb to the inner circumferential surface of the cylindrical workpiece Wa, although the joining position X cannot be visually recognized from the outside.

[Second embodiment]
Next, a specific example of the second embodiment (second ultrasonic bonding method) of the present invention will be described with reference to FIGS. 4A and 4B.

First, FIG. 4A shows a cross-sectional view near the joining position Y. The same cylindrical work Wa and the linear work Wb of the first embodiment are used. Note that the linear workpiece Wb and the guide block 20 described later are shown three-dimensionally.

In this embodiment, the horn tip 16 has a structure in which a protrusion 16c is provided at the tip 16b. As shown in the figure, the protrusion 16c has a cylindrical shape with a diameter of e and a length of f. Note that the diameter e is approximately 1.5 to 3.0 [mm], and the length f is approximately 2.0 to 4.0 [mm]. Since the horn tip 16 is inserted from the end of the cylindrical workpiece Wa to reach the joining position Y, it is preferable that the joining position Y is a position relatively close to the end.

When moving the leading end of the linear workpiece Wb to the joining position Y, the linear workpiece Wb is set on the cylindrical guide block 20 and moved by a predetermined distance. It is preferable that the linear workpiece Wb is inserted from the end opposite to the end into which the horn tip 16 is inserted, of both ends of the cylindrical workpiece Wa.

During movement, the leading end of the linear workpiece Wb projects from the end of the guide block 20 by about 0.25 to 0.50 [mm]. The cylindrical workpiece Wa may be moved, and the relative position between the cylindrical workpiece Wa and the guide block 20 may be changed.

Then, by pressing the linear work Wb from above with the protrusion 16c of the horn tip 16 and applying ultrasonic vibration (amplitude is about 5.0 [μm] at maximum), the linear work Wb is shaped into a cylindrical shape. It can be joined to the inner circumferential surface of the shaped workpiece Wa.

Further, in this embodiment, the cylindrical workpiece Wa is fixed by jigs 9a and 9b that sandwich it from above and below. Since the lower jig 9a is located on the lower surface side of the bonding position Y, it also plays the role of an anvil during ultrasonic bonding.

At least one protrusion 16c is provided on the tip 16b. Since the protrusion 16c is a very small component, it is preferably molded integrally with the horn tip 16.

On the other hand, as shown in FIG. 4B, the projection 16c may be configured to be detachable from the tip 16b. When attaching the projection 16c to the tip 16b of the horn tip 16, it is necessary to provide a screw hole in the tip 16b in advance. Further, it is necessary to provide a screw thread at one end of the protrusion 16c. With this method, an appropriate protrusion can be selected depending on the joining purpose and the material of the workpiece.

Finally, a flowchart of the second ultrasonic bonding method will be described with reference to FIG.

First, the cylindrical workpiece Wa is fixed (step S11). In this embodiment, the cylindrical workpiece Wa is fixed by the jigs 9a and 9b, but when the linear workpiece Wb is moved to the joining position Y, no displacement occurs, and furthermore, rotation of the cylindrical workpiece Wa is prevented during joining. can do.

Next, the linear workpiece Wb is moved to the joining position Y (step S12). Specifically, the guide block 20 to which the linear workpiece Wb is fixed is moved to the joining position Y using, for example, an xy stage device.

Next, the protrusion 16c of the horn tip 16 is inserted into the cylindrical workpiece Wa, and set so that the protrusion 16c is above the joining position Y (step S13).

Furthermore, the workpieces are joined by bringing the horn tip 16 into contact and applying ultrasonic vibrations (step S14). Thereby, the operator can join the linear workpiece Wb to the inner circumferential surface of the cylindrical workpiece Wa, although the joining part cannot be seen from the outside.

In the embodiment described above, it is important to reliably move the linear workpiece Wb to the joining position X (joining position Y). For this reason, it is preferable to perform precise positioning using, for example, an xy stage device.

In the horn tip 16 of the second embodiment, the protrusion 16c does not need to have a cylindrical shape, and for example, a protrusion 16c having a planar joint surface may be used. Further, a convex portion or a concave portion may be formed on the bonding surface to improve the bonding efficiency.

DESCRIPTION OF SYMBOLS 1... Ultrasonic bonding device, 2... Ultrasonic vibrator, 3... Ultrasonic expansion horn, 3a... Flange part, 4... Ultrasonic LT horn, 4a... Diagonal slit, 6, 16... Horn chip, 6a... Base part, 6b, 16b... Tip portion, 6c... End face, 7... Anvil, 7a... Guide groove, 7b... Shallowest part, 8... Oscillator, 9a, 9b... Jig, 10... Pressure device, 12... Sensor, 13... Control device, 14... Display device, 16c... Projection, 20... Guide block, Wa... Cylindrical workpiece, Wb... Linear workpiece.

Claims (2)

An ultrasonic bonding method using ultrasonic complex vibration,
inserting an elongated workpiece and a guide block having a longitudinally extending groove on its outer peripheral surface into the cylindrical workpiece ;
positioning the tip of the elongated workpiece along the groove of the guide block at a joining position on the inner peripheral surface of the cylindrical workpiece;
the step of applying the ultrasonic complex vibration by bringing the bonding tip into contact with the cylindrical workpiece at a position corresponding to the bonding position;
Ultrasonic bonding method. An ultrasonic bonding device using ultrasonic complex vibration,
A joining chip,
an ultrasonic complex vibration system that applies ultrasonic complex vibration to the bonding chip;
a holding mechanism that holds a cylindrical workpiece;
a guide block that can be inserted into the cylindrical workpiece and has a longitudinal groove on the outer peripheral surface of the cylindrical member;
a positioning mechanism that positions the tip of the elongated workpiece along the groove of the guide block to a joining position on the inner circumferential surface of the cylindrical workpiece.
Ultrasonic bonding equipment.