Ultrasonic bonding method and ultrasonic bonding apparatus

Abstract

To provide an ultrasonic junction method that can increase heat energy generated on a bonded interface, which inhibiting damage on a workpiece, and an ultrasonic junction device.SOLUTION: An ultrasonic junction method includes a junction step of joining a workpiece W by applying ultrasonic vibrations to the workpiece W. In the junction step, the workpiece W is vibrated with amplitude smaller than amplitude of the ultrasonic vibrations.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to an ultrasonic bonding method and an ultrasonic bonding apparatus.

Background Art

[0002] For example, Japanese Patent Application Laid-Open No. 2019-126822 discloses a bonding method for bonding a plurality of metal foils to a current collector plate by applying ultrasonic vibration to the plurality of metal foils placed on the current collector plate.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When bonding metal plates by an ultrasonic bonding method, if the pressing force by a horn or the amplitude of ultrasonic vibration applied from the horn to the metal plate is increased in order to increase the frictional heat energy that causes diffusion bonding, there is a concern that the metal plate may be damaged.

[0005] An object of the present disclosure is to provide an ultrasonic bonding method and an ultrasonic bonding apparatus capable of increasing the thermal energy generated at the bonding interface while suppressing damage to the workpiece.

Means for Solving the Problems

[0006] An ultrasonic bonding method according to an aspect of the present disclosure includes a bonding step of bonding the workpiece by applying ultrasonic vibration to the workpiece, and in the bonding step, the workpiece is vibrated at an amplitude smaller than the amplitude of the ultrasonic vibration.

[0007] Further, an ultrasonic bonding apparatus according to an aspect of the present disclosure includes a holding member that holds a workpiece, a biasing member that biases the holding member toward the workpiece, and a horn that applies ultrasonic vibration to the workpiece held by the holding member. The biasing member biases the holding member toward the workpiece so that the workpiece vibrates with an amplitude smaller than the amplitude of the ultrasonic vibration.

Advantages of the Invention

[0008] According to the present disclosure, it is possible to provide an ultrasonic bonding method and an ultrasonic bonding apparatus capable of increasing the thermal energy generated at the bonding interface while suppressing damage to the workpiece.

Brief Description of the Drawings

[0009]

Figure 1

Embodiments for Carrying Out the Invention

[0010] Embodiments of the present disclosure will be described with reference to the drawings. In the drawings referred to below, the same or corresponding members are denoted by the same reference numerals.

[0011] FIG. 1 is a diagram schematically showing an ultrasonic bonding apparatus in an embodiment of the present disclosure. This ultrasonic bonding apparatus 1 is suitable for bonding dissimilar metals that form an interdiffusion layer with each other, and is preferably used, for example, for bonding an external terminal of a power storage cell and a bus bar.

[0012] The ultrasonic bonding apparatus 1 includes a holding member 10, a biasing member 20, and a horn 30.

[0013] The holding member 10 holds the workpiece W. The workpiece W has a first member W1 and a second member W2 disposed on the first member W1. In the present embodiment, an external terminal of a power storage cell is used as the first member W1, and a bus bar is used as the second member W2. The external terminal is made of copper, and the bus bar is made of aluminum. However, the first member W1 and the second member W2 are not limited to the external terminal and the bus bar as long as they are dissimilar metals that form a diffusion layer with each other.

[0014] The holding member 10 holds the first member W1. Specifically, the holding member 10 sandwiches the first member W1 from both sides in the vibration direction of the horn 30 (the left - right direction in FIG. 1). Note that the holding member 10 may also sandwich the first member W1 from both sides in the direction orthogonal to the vibration direction of the horn 30 (the direction orthogonal to the paper surface in FIG. 1).

[0015] The horn 30 applies ultrasonic vibration to the workpiece W held by the holding member 10. The horn 30 vibrates along the surface of the second member W2 as indicated by the arrow AR1 in FIG. 1.

[0016] The biasing member 20 biases the holding member 10 toward the workpiece W so that the workpiece W vibrates with an amplitude smaller than the amplitude of the ultrasonic vibration and at the same frequency as the frequency of the ultrasonic vibration. The biasing member 20 biases the holding member 10 toward the workpiece W so that the workpiece W vibrates in a direction parallel to the vibration direction of the ultrasonic vibration (the left - right direction in FIG. 1).

[0017] The biasing force by the biasing member 20 is such that the contact surface pressure acting from the holding member 10 on the workpiece W is 10 N / mm 2 or more, and is set so that the amplitude of the workpiece W is 60% or less of the amplitude of the ultrasonic vibration. The amplitude of the workpiece W is preferably 10 μm or less.

[0018] The ultrasonic bonding apparatus 1 in this embodiment is capable of executing an ultrasonic bonding method including a bonding process. The bonding process is a process of bonding the workpiece W by applying ultrasonic vibration to the workpiece W. In this bonding process, the workpiece W is vibrated at an amplitude smaller than the amplitude of the ultrasonic vibration. In this bonding process, the workpiece W is vibrated in a direction parallel to the vibration direction of the ultrasonic vibration. Further, in the bonding process, it is preferable to vibrate the workpiece W at an amplitude of 60% or less of the amplitude of the ultrasonic vibration.

[0019] In the ultrasonic bonding method described above, let the power during the vibration of the horn 30 be W1, the bonding time be t1, and the conversion efficiency from ultrasonic vibration to thermal energy at the workpiece interface be a1. On the other hand, when the workpiece W is fixed as in the prior art, let the power during the vibration of the horn 30 be W2, the bonding time be t2, and the conversion efficiency from ultrasonic vibration to thermal energy at the workpiece interface be a2.

[0020] Compared with the case where the workpiece W is fixed, in this embodiment, it is easier to vibrate the horn 30, so W1 < W2. Since the conversion efficiency from ultrasonic vibration to thermal energy at the workpiece interface decreases, a1 < a2. And since the bonding time becomes longer, t1 > t2.

[0021] However, since the relationship of W1·t1·a1 > W2·t2·a2 holds, the total amount of thermal energy generated at the bonding interface of the workpiece W is larger in this embodiment. That is, compared with the case where the workpiece W is fixed, although the conversion efficiency from ultrasonic vibration to thermal energy at the workpiece interface decreases, since the time required for bonding the workpiece W becomes longer, the thermal energy generated at the bonding interface of the workpiece W becomes larger than when the workpiece W is fixed.

[0022] Therefore, in this embodiment, it is possible to increase the thermal energy generated at the bonding interface of the workpiece W while suppressing damage to the workpiece W. For this reason, productivity is improved.

[0023] The exemplary embodiments described above are specific examples of the following aspects.

[0024] The ultrasonic bonding method in the above embodiment includes a bonding step of bonding the workpiece by applying ultrasonic vibration to the workpiece. In the bonding step, the workpiece is vibrated at an amplitude smaller than the amplitude of the ultrasonic vibration.

[0025] In this ultrasonic bonding method, although the conversion efficiency from ultrasonic vibration to thermal energy at the workpiece interface decreases compared to the case where the workpiece is fixed, the time required for bonding the workpiece becomes longer. Therefore, the thermal energy generated at the bonding interface of the workpiece becomes larger than in the case where the workpiece is fixed. Thus, while suppressing damage to the workpiece, the thermal energy generated at the bonding interface of the workpiece increases.

[0026] Also, in the bonding step, the workpiece may be vibrated at an amplitude of 60% or less of the amplitude of the ultrasonic vibration.

[0027] In this way, the above effects can be obtained more reliably.

[0028] Also, in the bonding step, it is preferable that the workpiece is vibrated in a direction parallel to the vibration direction of the ultrasonic vibration.

[0029] The ultrasonic bonding apparatus in the above embodiment includes a holding member for holding a workpiece, a biasing member for biasing the holding member toward the workpiece, and a horn for applying ultrasonic vibration to the workpiece held by the holding member. The biasing member biases the holding member toward the workpiece so that the workpiece vibrates at an amplitude smaller than the amplitude of the ultrasonic vibration.

[0030] With this ultrasonic bonding apparatus, it is possible to increase the thermal energy generated at the bonding interface of the workpiece while suppressing damage to the workpiece.

[0031] Also, it is preferable that the biasing member biases the holding member toward the workpiece so that the workpiece vibrates at the same frequency as the frequency of the ultrasonic vibration.

[0032] Also, the biasing force by the biasing member is such that the contact surface pressure acting on the work from the holding member is 10 N / mm 2 or more, and the amplitude of the work may be set to be 60% or less of the amplitude of the ultrasonic vibration.

[0033] In this way, for example, it becomes possible to use a negative electrode terminal plate of a storage battery and a bus bar as the work.

[0034] It should be noted that the embodiments and examples disclosed this time should be considered as illustrative in all respects and not restrictive. The scope of the present invention is shown not by the description of the above embodiments and examples but by the claims, and further includes all changes within the meaning and scope equivalent to the claims.

Explanation of Reference Numerals

[0035] 1 Ultrasonic bonding device, 10 Holding member, 20 Biasing member, 30 Horn, W Work.

Claims

Claim 1: A bonding step of bonding the external terminal and the bus bar of the storage cell to each other by applying ultrasonic vibration to the external terminal and the bus bar, wherein, in the bonding step, the external terminal and the bus bar are vibrated at an amplitude smaller than the amplitude of the ultrasonic vibration while the external terminal is sandwiched between a pair of holding members from both sides in the vibration direction of the ultrasonic vibration applied to the external terminal and the bus bar, wherein, in the bonding step, the contact surface pressure acting on the external terminal from the holding member is 10 N / mm2 or more, and the external terminal and the bus bar are vibrated at an amplitude of 60% or less of the amplitude of the ultrasonic vibration. An ultrasonic bonding method. Claim 2: The ultrasonic bonding method according to claim 1, wherein, in the bonding step, the external terminal and the bus bar are vibrated at an amplitude of 10 µm or less. Claim 3: The ultrasonic bonding method according to claim 1 or 2, wherein, in the bonding step, the holding member sandwiches the external terminal from both sides in a direction orthogonal to the vibration direction. Claim 4: A holding member for holding an external terminal of a storage cell, a biasing member for biasing the holding member toward the external terminal, and a horn for applying ultrasonic vibration to the external terminal held by the holding member and the bus bar placed on the external terminal, wherein the holding member sandwiches the external terminal from both sides in the vibration direction of the ultrasonic vibration applied to the external terminal and the bus bar and from both sides in a direction orthogonal to the vibration direction, and the biasing member biases the holding member toward the external terminal so that the external terminal and the bus bar vibrate at an amplitude smaller than the amplitude of the ultrasonic vibration. An ultrasonic bonding apparatus. Claim 5: The ultrasonic bonding apparatus according to claim 4, wherein the biasing member biases the holding member toward the external terminal so that the external terminal and the bus bar vibrate at the same frequency as the frequency of the ultrasonic vibration. Claim 6: The biasing force by the biasing member is such that the contact surface pressure acting from the holding member to the external terminal is 10 N / mm ２ or more, and the amplitudes of the external terminal and the bus bar are set to be 60% or less of the amplitude of the ultrasonic vibration. The ultrasonic bonding device according to claim 4 or 5.

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