JPH06155051A - Ultrasonic bonding method for metal foil - Google Patents

Abstract

(57) [Abstract] [Purpose] It is an object of the present invention to obtain an ultrasonic bonding method for metal foils, which enables bonding without breaking the metal foils. [Structure] A metal foil 2 is stacked on a metal plate 3 on a machined surface 1a of an anvil 1, and a machined surface 4a of an ultrasonic horn 4 that vibrates substantially parallel to the machined surface 1a of the anvil 1 is pressed against the metal foil 2. In the ultrasonic bonding method of the metal foil 2 for bonding the metal foil 2 and the metal plate 3, the processed surface 1a of the anvil 1 is a sandblasted rough surface, and the processed surface of the ultrasonic horn 4 is Reference numeral 4a denotes an uneven surface processed at a constant pitch. This metal foil 2 is placed on the processed surface 1a of the anvil 1 and overlaps with the metal plate 3, and the surface of the metal plate 3 which is not in contact with the metal foil is super-extended. This is an ultrasonic bonding method for metal foils pressed against the processed surface 4a of the sonic horn 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for ultrasonically bonding a metal foil, which is suitable for bonding a collector foil and a lead in a lithium ion secondary battery, for example.

[0002]

2. Description of the Related Art Conventionally, as a method of welding metal plates,
The ultrasonic welding method was widely used. This is done by stacking a metal plate and a metal plate on the machined surface of the anvil and pressing the machined surface of an ultrasonic horn that oscillates substantially parallel to the machined surface of the anvil from above and press the metal plate and metal This is a method of joining with a plate. Here, the processed surface of the anvil and the processed surface of the ultrasonic horn are each a concavo-convex surface processed in a pyramid shape at a constant pitch, and the metal plate is applied to those having a thickness of 50 μm or more. Was there.

[0003]

However, in the above-described conventional ultrasonic bonding method for a metal plate, when a metal plate having a thickness of 50 μm or less is used, the metal plate will be broken and the one which can be used. It could not be manufactured.

For example, when an ultrasonic horn is pressed from the side of the copper foil having a thickness of 10 μm, the copper foil having a thickness of 10 μm joins at the point of contact with the horn, but the copper foil breaks around the joint. Will end up. Further, when a pyramid-shaped surface is used for the anvil, there is a problem that holes are easily formed in the foil and the joining condition is not easy.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an ultrasonic bonding method for metal foils, which enables bonding without breaking the metal foils.

[0006]

As shown in FIG. 1, for example, as shown in FIG. 1, a method for ultrasonically bonding metal foils according to the present invention is such that a metal foil 2 is superposed on a processed surface 1a of an anvil 1 and a metal plate 3 and then, The processed surface 4a of the ultrasonic horn 4 that vibrates substantially parallel to the processed surface 1a of the anvil 1 is pressed against the metal foil 2
In the ultrasonic bonding method of the metal foil 2 for bonding the metal plate 3 and the metal plate 3, the machined surface 1a of the anvil 1 is a roughened surface subjected to sandblasting, and the machined surface 4a of the ultrasonic horn 4 has a constant pitch. This is a processed uneven surface, and this metal foil 2 is arranged on the processed surface 1 a of the anvil 1 to be a metal plate 3.
And the processed surface 4a of the ultrasonic horn 4 is pressed against the surface side of the metal plate 3 which is not in contact with the metal foil.

The ultrasonic bonding method of the metal foil of the present invention is the ultrasonic bonding method having the above-mentioned structure in which the thickness of the metal foil 2 is 5 μm to 30 μm.

[0008]

According to the ultrasonic bonding method for metal foils of the present invention, the metal foil 2 and the metal plate 3 are superposed on the processed surface 1a of the anvil 1.
From above, press the processed surface 4a of the ultrasonic horn 4 that vibrates substantially parallel to the processed surface 1a of the anvil 1,
In the ultrasonic bonding method of the metal foil 2 for bonding the metal foil 2 and the metal plate 3, the processed surface 1a of the anvil 1 is a sandblasted rough surface, and the processed surface 4a of the ultrasonic horn 4 is The metal foil 2 is an uneven surface machined at a constant pitch, and the metal foil 2 is placed on the machined surface 1a of the anvil 1 and overlapped with the metal plate 3. By using the method of pressing with the processed surface 4a of No. 4, it is possible to join the metal foils without forming holes due to cutting or tearing in the metal foils.

Further, according to the ultrasonic bonding method of the metal foil of the present invention, by using the ultrasonic bonding method having the above-mentioned constitution in which the thickness of the metal foil 2 is 5 μm to 30 μm, even in an extremely thin metal foil, It is possible to join the metal foils without forming holes due to breakage or tears.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the ultrasonic bonding method for metal foils of the present invention will be described below with reference to FIGS.

FIG. 1 shows the entire apparatus used in the ultrasonic bonding method for the metal foil of this embodiment. Here, 1 indicates an anvil, and rectangular processing surfaces 1a are provided on both sides of each surface in the longitudinal direction of the anvil 1, and a total of eight surfaces are provided on each side (Fig. 2). The processed surface is sandblasted.

On the machined surface 1a of the anvil 1, a metal foil indicated by 2 and leads indicated by 3 are installed. In this case, the portion where the metal foil 2 and the lead 3 are to be joined is just processed. It is necessary to be within the range of the surface 1a. Copper foil as the metal foil 2 (thickness is 5 μm to 30 μm)
Alternatively, aluminum foil (thickness: 5 μm to 30 μm) is used, and the lead 3 is a nickel plate (thickness: 50 μm to 100 μm).
m) or aluminum plate (thickness is 100 μm to 200 μm)
Was used.

Reference numeral 4 denotes an ultrasonic horn, and this ultrasonic horn 4 generates ultrasonic waves vibrating in the central axis direction. Near the tip of the ultrasonic horn 4, the processed surface (group) 4a is symmetrical to the horizontal surface including the central axis on the upper surface side and the lower surface side.
Are provided (see FIGS. 3 and 4). This processing surface 4
Pyramid-shaped irregularities are provided at a with a constant pitch. In order to join the metal foil 2 and the lead 3,
By pushing down the ultrasonic horn 4 in the vertical direction, the processed surface 4 a of the ultrasonic horn 4 is pressed against the lead 3.

Next, various conditions adopted in this embodiment will be described.

Order of stacking metal foil and lead As shown in FIG. 1, the metal foil 2 is placed on the anvil 1 side and the lead 3 is placed on the ultrasonic horn 4 side, and the ultrasonic horn 4 is pressed from the lead 3 side, Ultrasonic oscillating and joining.

The reason why the ultrasonic horn 4 is pressed from the lead 3 side, in other words, the ultrasonic horn 4 is not pressed from the metal foil 2 side, is as follows. Is. First, metal foil 2
This is due to the large amount of damage caused by the horns, and the peeling strength after joining decreases. When the copper foil 2 and the nickel plate 3 are joined under the same conditions, and then the peel strength is measured (see FIG. 5), when the ultrasonic horn 4 is pressed against the nickel plate 3 side and joined, the peel strength P = 1 kg.
On the other hand, when joining from the copper foil 2 side, P =
It is 0.3 kg, and about 3 times the strength is obtained. Further, after bonding, holes are formed in the copper foil (thickness 10 μm), and nickel is easily exposed. This also causes a short circuit. In addition, wrinkles are likely to occur in the metal foil after joining, and the range of optimum conditions is narrow.

Surface roughness of machined surface of anvil The machined surface of anvil is sandblasted, and its surface roughness is Rm.
The range was ax = 18 to 25 μm. Table 1 shows the surface roughness of the anvil, the finishing method, and the result of ultrasonic bonding.

[0018]

[Table 1]

As can be seen from the results shown in Table 1, sample C and sample D, that is, surface roughness Rmax = 18 to
In the range of 25 μm, slippage of the metal foil did not occur and good joining results were obtained. When the surface roughness Rmax of the machined surface of the anvil is less than 8 μm, the gripping force of the metal foil at the time of joining is reduced, and after the joining, wrinkles are often generated on the metal foil. When the surface roughness Rmax is 25 μm or more,
Holes are formed in the copper foil after joining, nickel is easily exposed, and the joining strength is reduced. In addition, if the processed surface of the anvil is sandblasted, there will be no holes in the copper foil after joining,
It has advantages such as low processing cost and no metal foil sticking to the anvil after joining.

Conditions of ultrasonic horn The processing pitch of the horn eyes of the ultrasonic horn is 0.3 mm to
The range was 0.7 mm. If the processing pitch is less than 0.3 mm, the grip force between the horn and the lead (tab) is reduced, and after the joining, wrinkles are often generated in the metal foil. on the other hand,
If it exceeds 0.7 mm, the joining area is reduced and the peeling strength is reduced.

The contact pressure of the ultrasonic horn is shown in Table 2 in each case of the combination of the nickel plate lead and the copper foil and the combination of the aluminum plate lead and the aluminum foil.
The range is as shown in.

[0022]

[Table 2]

When the contact pressure is lower than the lower limit of the range shown in Table 2, sufficient bonding strength cannot be obtained and slippage occurs between the metal foil and the lead plate. On the contrary, when the contact pressure is higher than the upper limit value shown in Table 2, there is a disadvantage that the diaphragm in the ultrasonic actuator causes seizure.

The end face amplitude of the ultrasonic horn was set in the range of 10 to 15 μm in each case of the combination of the nickel plate lead and the copper foil and the combination of the aluminum plate lead and the aluminum foil. If the amplitude is smaller than the above range, sufficient bonding strength cannot be obtained. Further, if the amplitude is larger than this range, perforation occurs in the metal foil, resulting in a decrease in bonding strength.

The bonding energy of the ultrasonic horn was set to the range shown in Table 3 in each of the combination of the nickel plate lead and the copper foil and the combination of the aluminum plate lead and the aluminum foil.

[0026]

[Table 3]

If the bonding energy is smaller than the above range, sufficient bonding strength cannot be obtained. Further, if the energy is larger than this range (only in the case of the combination of the lead of the nickel plate and the copper foil), perforation occurs in the copper foil, resulting in a decrease in the bonding strength.

From the above, according to this example, it is possible to join the metal foils without forming holes due to breaks or tears in the metal foils. Therefore, it is useful for stable joining of ultra-thin sheets and has a wide range of applications. Further, the peeling strength after joining can be improved, and the adhesion of the metal foil to the anvil, that is, the occurrence of biting can be prevented. In addition, the optimum range of conditions for bonding (pressure, bonding energy, range of eyes, etc.) is wide, and the conditions can be easily set.

The present invention is not limited to the above-mentioned embodiments, and it goes without saying that various other configurations can be adopted without departing from the gist of the present invention.

[0030]

As described above, according to the present invention,
Since the metal foils can be bonded to each other without causing holes due to breakage or tears in the metal foils, it is useful for stable bonding of the ultrathin sheets and can be applied in a wide range of applications. Further, the peeling strength after joining can be improved, and the adhesion of the metal foil to the anvil, that is, the occurrence of biting can be prevented. In addition, the optimum range of conditions for bonding (pressure, bonding energy, range of eyes, etc.) is wide, and the conditions can be easily set.

[Brief description of drawings]

FIG. 1 is a perspective view showing an entire apparatus used in the ultrasonic bonding method for metal foils of the present invention.

FIG. 2 is a structural diagram of an anvil used in the ultrasonic bonding method for metal foils of the present invention.

FIG. 3 is a structural diagram of a horn used in the ultrasonic bonding method for metal foils of the present invention.

FIG. 4 is a structural diagram of a horn used in the ultrasonic bonding method for metal foils of the present invention.

FIG. 5 is a perspective view showing a peeling strength measuring method.

[Explanation of symbols]

 1 Anvil 1a Processing surface 2 Metal foil 3 Lead (tab) 4 Ultrasonic horn 4a Processing surface 5 Ultrasonic bonding actuator

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[Procedure amendment]

[Submission date] March 15, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0023

[Correction method] Change

[Correction content]

When the contact pressure is lower than the lower limit of the range shown in Table 2, sufficient bonding strength cannot be obtained and slippage occurs between the metal foil and the lead plate. On the contrary, when the contact pressure is higher than the upper limit value shown in Table 2, there is a disadvantage that the diaphragm in the ultrasonic actuator is seized , cracked or the like .

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 4

[Correction method] Change

[Correction content]

[Figure 4]

Claims (2)

[Claims] 1. A metal foil is superposed on a metal plate on a machined surface of an anvil, and a machined surface of an ultrasonic horn that vibrates substantially in parallel to the machined surface of the anvil is pressed against the metal foil to form the metal foil. In the ultrasonic bonding method of the metal foil for bonding the metal plate, the processed surface of the anvil is a sandblasted rough surface, and the processed surface of the ultrasonic horn is an uneven surface processed at a constant pitch. Yes, the above-mentioned metal foil is arranged on the processed surface of the anvil and overlapped with the metal plate, and the surface of the metal plate that is not in contact with the metal foil is pressed by the processed surface of the ultrasonic horn. Sonic bonding method. 2. The ultrasonic bonding method for a metal foil according to claim 1, wherein the thickness of the metal foil is 5 μm to 30 μm.