JP2015213945A - Ultrasonic junction method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic junction method for solving a problem that an anvil and a workpiece stick after junction so that the workpiece becomes hard to leave, and for improving the strength of the junction.SOLUTION: After a forging press was so set with only a power collection terminal 11 as was arranged between no-protrusion forging tools 12 and 13, the power collection terminal 11 is compressed under a pressure vertically by the two no-protrusion forging tools 12 and 13 and is work-hardened. After the compression, the power collection terminal 11 is set together with an electrode foil 14 between an anvil 15 and a horn 16 of an ultrasonic junction machine, and is joined by applying a vertical pressure and an ultrasonic vibration in any direction of a joint surface.

Description

  The present invention relates to metal bonding, and more particularly, to an ultrasonic bonding method for battery electrode foil and current collecting terminal.

  Currently, in the process of ultrasonically bonding the electrode foil and the current collecting terminal of the battery, studies are being made to increase the bonding strength at the bonding interface between the electrode foil and the current collecting terminal by using soft metal as the current collecting terminal.

  In ultrasonic bonding, an electrode foil on the horn (vibration source) side is arranged, and a current collecting terminal is arranged on the anvil (fixed end) side. At this time, the greater the difference in movement in the vibration direction between the electrode foil and the current collecting terminal, the greater the frictional heat and the more likely the bonding strength is born. However, if the current collecting terminal on the anvil side is too soft, the joint surface of the current collecting terminal is deformed more than necessary due to the vertical pressurization during joining, and the vibration of the horn and the electrode foil is hindered.

  As an example of such joining, Patent Document 1 describes that a metal and a current collecting terminal are sandwiched between an anvil and a horn having protrusions, and the metal and the current collecting terminal are joined by ultrasonically vibrating the horn. Yes.

JP 2006-181623 A

  The present invention has been made to solve such a problem, and solves the problem that an anvil and a current collecting terminal (work) are stuck after joining, making it difficult to remove the current collecting terminal. The object is to increase the bonding strength in metal bonding.

  The invention according to the present invention includes a step of pressing and compressing a current collecting terminal from both sides with a non-projecting tool, a pressure-compressing current collecting terminal, and the electrode foil from the electrode foil side. A step of applying pressure and ultrasonic waves with a projection tool and bonding the electrode foil and the current collecting terminal.

  According to the present invention, it is possible to suppress the friction / deformation of the protruding portion of the anvil which is a protruding tool, and it is difficult to remove the current collecting terminal, and the bonding surface is prevented from being excessively deformed to improve the bonding strength. Can be made.

It is a figure which shows the process of the joining method concerning embodiment. It is a figure of the photograph which shows the observation direction of the junction part using the joining method concerning embodiment. It is a figure of the photograph which shows the comparison of the cross-sectional shape of the junction part using the joining method concerning embodiment, and the joining method which does not perform pressurization and hardening before ultrasonic joining. It is a figure which shows the motion of the horn in the joining method which does not perform pressurization and hardening before ultrasonic joining. It is a figure which shows the comparison of the joining strength of the joining method concerning embodiment, and the joining method which does not perform pressurization and hardening before ultrasonic joining.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram illustrating each step of the bonding method according to the embodiment.
A forging press is installed for use in processes prior to ultrasonic bonding. Then, as shown in FIG. 1A, only the aluminum current collecting terminal 11 is disposed between the protrusion-free forging tools 12 and 13 and set in the forging press. As a material for the current collecting terminal, soft metals other than aluminum can be used. For example, soft metals such as copper, silver, and aluminum alloys are suitable.

  In a typical example, in the state set in the forging press, the upper surface of the forging tool 12 is flat and has no protrusions. In the same state, the lower surface of the forging tool 13 is also flat and has no protrusions. The current collecting terminal 11 to be set is preferably one in which the shape used for the current collecting terminal of the battery is previously cut and processed. For example, a shape such as a flat plate is suitable.

  After the setting, as shown in FIG. 1B, the current collecting terminal 11 is pressed and compressed from above and below with two non-projecting forging tools 12 and 13 and work-cured. As a guide, the current collecting terminal 11 is compressed until the terminal plate thickness is reduced by 2 to 5% with respect to the plate thickness before pressurization, as shown in FIG.

  After compression, as shown in FIG. 1D, the electrode foil 14 is placed on the cured surface of the current collecting terminal 11, and the current collecting terminal 11 and the electrode foil 14 are connected to the anvil 15 and the horn 16 of the ultrasonic bonding machine. Set in between, pressurization in the vertical direction and joining by applying ultrasonic vibration in any direction of the joining surface. Specifically, the current collector terminal 11 and the electrode foil 14 are set on the anvil 15 having the protrusion, the horn 16 having the protrusion is brought into contact with the electrode foil 14 side, and the ultrasonic vibration is applied from the horn 16. To do.

Examples of the bonding method according to the embodiment are shown below.
The electrode foil is formed by stacking 40 metal thin films having a thickness of about 15 μm. The current collecting terminal is a metal plate having a thickness of 1 mm processed into a predetermined shape.

  In FIG. 2, it is a figure which shows the observation direction of the joined current collection terminal. As shown in FIG. 2, the joined member was cut along a plane perpendicular to the joining surface. And the cross-sectional photograph observed from the direction perpendicular | vertical with respect to the cut surface is shown in FIG.

  FIG. 3A is a cross-sectional view when ultrasonic bonding is performed without pressurizing the current collecting terminal. When the current collecting terminal is pressurized together with the ultrasonic bonding without being pressurized and cured in advance before the ultrasonic bonding, the current collecting terminal is deformed from a flat surface to a shape having a recess. As a result, gaps are generated between the electrode foils or between the current collecting terminal and the electrode foil.

  That is, when pressure and curing are not performed before ultrasonic bonding, the original ultrasonic vibration of the horn 16 is hindered and moves along the concave portion of the bonding surface 17 as shown in FIG. The terminal and the electrode foil cannot be kept in close contact with each other, resulting in a situation in which friction is difficult to occur.

  On the other hand, in the joining method according to the present embodiment, since the current collecting terminal is cured in advance, the joining surface of the current collecting terminal is kept flat, and the current collecting terminal and the electrode foil are in close contact with each other. Friction occurs due to ultrasonic vibration in the joint surface direction.

  FIG. 3B is a cross-sectional view when the current collector terminal is pressed and cured and then pressed together with ultrasonic bonding. In the bonding method of the present embodiment, when the pressure is applied together with the ultrasonic bonding, the current collecting terminal is kept flat, so that the current collecting terminal is in contact with the electrode foil and vibrates, and friction is generated. . As a result, the electrode foils are closely bonded, and the current collecting terminals and the electrode foil are also bonded without a gap.

  Thus, since the joining method according to the present embodiment can generate sufficient friction between the current collector terminal and the electrode foil by ultrasonic vibration, the strength of joining by friction is improved.

  The improved strength will be described with reference to FIG. FIG. 5 is a diagram showing a comparison of bonding strength depending on a bonding method. The case where pressure and curing are not performed before ultrasonic bonding is shown as a soft terminal in FIG. 5, and the bonding strength is 129N. On the other hand, the case where pressure and curing are performed before ultrasonic bonding is shown as a hard terminal, and the bonding strength is 494N. That is, the bonding strength is improved nearly four times by applying pressure and curing before ultrasonic bonding.

  In addition, since a tool having no protrusion is used for the pressurization before joining, the tool with a protrusion at the time of joining only needs to be pressurized at the time of ultrasonic joining, and friction and deformation are reduced.

  As described above, the bonding method according to the present embodiment can be applied to the bonding of the electrode foil and the current collecting terminal in the battery manufacturing process, and before the ultrasonic bonding process, a soft metal such as aluminum is used as the material. Forging only the part to be joined of the terminal to be welded with a non-protruding tool different from the protruding tool, increasing the material density and hardening the terminal by pressing, and then ultrasonically bonding with the protruding tool In the process of pressurizing and curing before joining, it is not necessary to use a tool with protrusions, so it is possible to suppress friction and deformation of the protrusions of the anvil, which is a protrusion tool used for ultrasonic bonding, and It is possible to prevent the electric terminal from being easily detached, and to prevent excessive deformation of the bonding surface and improve the bonding strength.

11 Current collecting terminals 12, 13 Forging tool 14 Electrode foil 15 Anvil 16 Horn

Claims (1)

  A step of pressing and compressing the current collecting terminal from both sides with a non-projecting tool, curing the pressure collecting terminal and the electrode foil, and pressing the electrode foil from the electrode foil side with a protruding tool A method of joining the electrode foil and the current collecting terminal, comprising the step of joining by applying ultrasonic waves.