JP5556364B2 - Metal lead and its manufacturing method - Google Patents

Description

  The present invention relates to a metal lead with a copper plate made of an aluminum plate used for a nonaqueous electrolyte device or the like, and a method for manufacturing the same.

  For example, non-aqueous electrolyte batteries such as lithium ion batteries are used as power sources for small electronic devices. This non-aqueous electrolyte battery has a structure in which a positive electrode plate, a negative electrode plate, and an electrolytic solution are accommodated in an enclosure made of a multilayer film, and leads connected to the positive electrode plate and the negative electrode plate are sealed and taken out to the outside. Are known. In this case, a lead material made of an aluminum plate or an alloy conductor thereof is usually used on the positive electrode side.

  A lead made of an aluminum plate cannot be easily connected by soldering. In some cases, a plurality of nonaqueous electrolyte devices are connected in series to obtain a desired voltage. In this case, the lead of the aluminum plate and the lead of the copper plate are connected in electrical contact, but if moisture due to condensation adheres to the contact part, a local battery is formed between different types of metals, and the metal with the higher ionization tendency Has the problem of corrosion. In order to improve this, for example, Patent Document 1 discloses a lead member in which a copper lead member is joined to an aluminum lead member by cold welding.

JP 2008-108584 A

  FIGS. 7A to 7C schematically show a form in which the aluminum lead member 11 and the copper lead member 12 disclosed in Patent Document 1 are joined by cold welding. In order to pressurize the joint portion 13, dies (pressing dies) 14 and 15 are arranged above and below the joint portion. The pressing surface of at least one of the dies 14 and 15 (for example, the upper die 14) is provided with a convex portion 14a for causing deformation of the joint surface. The pressing surface of the other die 15 is flat or provided with a recess 15a corresponding to the protrusion 14a.

  The joining portion 13 of the aluminum lead member 11 and the copper lead member 12 is plastically deformed and closely joined by the dies 14 and 15 having irregularities on the pressing surface. In addition, as shown in FIG. 7D, the lead member processed as described above is covered with two insulating resin films 16 composed of an inner layer 16a and an outer layer 16b, for example. The sealing portion is used to seal the outer body of the water electrolyte battery.

  The insulating resin film must be closely adhered to the pressure contact portion of the lead member (aluminum plate and copper plate). However, in the above lead member, there is an unevenness in which the uneven shape of the die is copied at the pressure contact portion, and therefore a gap is likely to occur when an insulating resin film is applied thereto. If unevenness is provided on the pressing surface of the die, the processing cost increases. Therefore, it is more cost effective to use a flat die without unevenness.

  The present invention has been made in view of the above-described circumstances, and provides a metal lead in which a copper plate is connected and integrated with an aluminum plate by cold pressure welding using a flat pressure welding die having no unevenness on the pressing surface, and a method for manufacturing the same. With the goal.

Metal lead according to the present invention, the copper plate is joined by cold welding to one end portion of the rectangular aluminum plate, the bonded portion of a metal lead covered non-aqueous electrolyte for a device with an insulating resin film, the bonding portion is joined to the copper plate in a state where oxide films of the bonding surface of the end portion of the aluminum plate has been removed, characterized in that there are no irregularities in the joint portion.
The metal lead manufacturing method according to the present invention also includes a metal lead for a non-aqueous electrolyte device in which a copper plate is joined to one end portion of a rectangular aluminum plate by cold pressure welding, and the joined portion is covered with an insulating resin film. in the manufacturing method, the bonding portion was removed by polishing or diagonal shear an oxide film of the bonding surface of the end portion of the aluminum plate, and bonding the copper plate pressing surface is a flat crimping die, so that uneven bonding portion does not occur To .

  According to the metal lead and the method for manufacturing the same according to the present invention, since there is no unevenness in the connection portion, it is easy to reliably attach the insulating resin. Also, the processing cost of the die is low.

It is a figure explaining the outline of the metal lead by this invention. It is a figure which shows an example of the nonaqueous electrolyte device using the metal lead by this invention. It is a figure explaining an example which joins the aluminum plate and copper plate by this invention by cold pressure welding. It is a figure explaining the other example which joins the aluminum plate and copper plate by cold pressure welding by this invention. It is a figure explaining the other example which joins the aluminum plate and copper plate by cold pressure welding by this invention. It is a figure which shows the test result which joined the aluminum plate and copper plate by this invention by cold pressure welding. It is a figure explaining the subject which the conventional technology should solve.

Embodiments of the present invention will be described with reference to the drawings. 1A shows an example of a metal lead according to the present invention, FIG. 1B is a front view thereof, and FIG. 1C is a cross-sectional view thereof.
An aluminum lead 3 according to the present invention has a rectangular copper conductor plate 7 (hereinafter referred to as a copper plate), which will be described later, on one end of a rectangular aluminum conductor plate 5 (hereinafter referred to as an aluminum plate). And the joining portion is covered with an insulating resin film 6. The copper plate 7 includes a nickel-plated copper plate having a nickel plating on the outer peripheral surface thereof.

  The insulating resin film 6 covering the joint portion between the aluminum plate 5 and the copper plate 7 is stuck so as to protrude from the width direction of the plate and sandwich the joint portion of the plate from both sides. As shown in FIG. 1C, the insulating resin film 6 is formed of two layers of an inner layer 6a that is bonded or welded to the aluminum plate 5 and the copper plate 7, and an outer layer 6b that is fused to the battery outer package or the like. can do. The inner layer 6a is brought into close contact with an aluminum plate, a copper plate, and a joint portion thereof by heating and melting. The outer layer 6b has a higher melting point than the inner layer 6a, and retains its shape when sealed to the battery outer package.

2A shows an example in which the aluminum lead 3 shown in FIG. 1 is used for a nonaqueous electrolyte device such as a lithium ion battery or a capacitor, and FIG. 2B shows an example of sealing a metal lead. It is.
In the non-aqueous electrolyte battery 1, an aluminum lead 3 made of metal aluminum that does not dissolve in the electrolyte solution at a high potential is used on the positive electrode side, and the negative electrode side is made of nickel-plated copper. Copper leads 4 are often used. In the electric double layer capacitor, aluminum leads are used for both the positive electrode side and the negative electrode side.

The nonaqueous electrolyte battery 1 stores a positive electrode plate and a negative electrode plate, and an electrolyte solution, which are laminated via a separator, in an exterior body 2 made of a multilayer film containing a metal foil, as shown in FIG. In addition, the aluminum lead 3 on the positive electrode side and the copper lead 4 on the negative electrode side are taken out from the seal portion 2d of the outer package 2 through the insulating resin film 6 and configured.
The aluminum lead 3 is arranged so that a portion of the copper plate 7 is exposed to the outside, and is used for solder connection or direct connection with a copper conductor. The other end portion of the aluminum plate 5 remains an aluminum conductor and is connected to the electrode plate lead 8 in the battery as shown in FIG.

  The exterior body 2 serves as an exterior case for the nonaqueous electrolyte battery 1 and is sealed by, for example, sealing the seal portions 2d around the two rectangular multilayer films by heat welding. The multilayer film forming the outer package 2 is composed of a laminate of at least three layers, and the innermost layer film 2a is suitable for preventing the electrolyte from leaking out from the seal portion 2d without being dissolved by the electrolyte. A polyolefin resin (eg, maleic anhydride-modified low density polyethylene or polypropylene) is used. The metal foil layer 2b is made of a metal foil such as aluminum, copper, or stainless steel, and enhances the sealing performance against the electrolytic solution. The outermost layer film 2c is for protecting the thin metal foil layer 2b, and is formed of polyethylene terephthalate (PET) or the like.

  Both the aluminum lead 3 and the copper lead 4 are hermetically sealed by thermally sealing the insulating resin film 6 to the multilayer film of the outer package 2. The insulating resin film 6 can be formed of, for example, two layers of an inner layer 6a and an outer layer 6b, as described with reference to FIG. Then, the outer layer 6b and the exterior body 2 are fused to each other so that the metal foil 2b and the lead in the exterior body 2 are not electrically short-circuited and sealed. be able to.

  The non-aqueous electrolyte battery 1 described above can be integrated by connecting a protection circuit board 9 that protects the battery by monitoring the battery temperature and controlling the charge and discharge during actual use, or the positive side of a plurality of batteries. In some cases, the lead 3 and the lead 4 on the negative electrode side are electrically connected in series. In such a case, solder connection is not possible when ordinary aluminum leads are used. However, as shown in FIG. 2, by using the aluminum lead 3 having the solderable copper plate 7, it can be directly connected to the conductor pattern 9a of the protective circuit board 9 and can be easily assembled. In addition, it is possible to use the aluminum lead 3 on the positive electrode side and the copper lead 4 on the negative electrode side of a plurality of batteries connected in series.

  3-5 is a figure explaining the method to join the said aluminum plate 5 and the copper plate 7 by cold rolling. FIG. 3 shows an example in which an aluminum plate and a copper plate having the same thickness are joined to each other. As shown in FIG. 3A, the end portions of the aluminum plate 5 and the copper plate 7 having the same thickness are overlapped with each other. Shall be joined. As shown in FIG. 3B, the end portion of the aluminum plate 5 to be joined is obliquely sheared to form an oblique joining surface 5a from which the surface oxide film is removed. Similarly, the end portion of the copper plate 7 is also sheared obliquely to form a slanted joint surface 7a from which surface contamination and a nickel plating layer have been removed.

  Next, as shown in FIG. 3C, the diagonal joining surfaces 5a and 7a of both plates are brought into contact with each other, and press-contact dies 10a and 10b are arranged up and down. When the oblique joining surfaces 5 a and 7 a are overlapped with each other, the joining surface 7 a of the copper plate 7 that naturally overlaps the upper surface rises upward from the joining surface 5 a of the aluminum plate 5. The upper press-contacting die 10a and the lower press-contacting die 10b are both formed with flat pressing surfaces.

Next, as shown in FIG. 3D, a pressing force (load stress) is applied to the upper and lower pressing dies 10a and 10b to cold-weld the joined portions. By this pressure welding, the joining surfaces 5a and 7a are joined and integrated. At this time, the joining surfaces 5a and 7a before joining are plastically deformed into an indefinite shape as shown by the joining end portions 5c and 7c and are tightly joined. The remaining plate thickness after pressure welding deformation at the center portion of the pressure welding is (a) where the aluminum plate 5 side is (a) and the copper plate 7 side is (b). is (a + b) is approximately the thickness of the plate preparative ing.

  FIG. 4 shows an example in which an aluminum plate and a copper plate having different thicknesses are joined to each other. As shown in FIG. 4 (A), the thick aluminum plate 5 and the thin copper plate 7 ′ are joined to each other. It shall be. As shown in FIG. 4 (B), the end portion of the aluminum plate 5 to be joined is obliquely sheared in the same manner as in the example of FIG. 3 to form an oblique joining surface 5a from which the oxide film on the surface is removed. Similarly, the end portion of the copper plate 7 ′ is also obliquely sheared to form a slanted joint surface 7′a from which surface dirt and oxide layers have been removed.

  Next, as shown in FIG. 4C, the diagonal joining surfaces 5a and 7'a of both plates are brought into contact with each other, and the dies 10a and 10b are arranged above and below. Note that the pressing surfaces of the upper pressing die 10a and the lower pressing die 10b are both flat as in the example of FIG.

  Thereafter, as shown in FIG. 4D, a pressing force is applied to the upper and lower pressing dies 10a and 10b to cold-weld the joined portions. By this pressure welding, the joining surfaces 5a and 7'a are joined and integrated. At this time, the joining surfaces 5a and 7′a before joining are plastically deformed into an indeterminate shape as shown by the joining end portions 5c and 7′c by pressure welding and are tightly joined. The remaining plate thickness after the pressure deformation at the center portion of the pressure contact is (a) on the aluminum plate 5 side and (b) on the copper plate 7 ′ side, and (a> b), the joining thickness (a + b) Are compressed and bonded to each other than the thickness on the thick aluminum plate 5 side.

  FIG. 5 is an example in which an aluminum plate and a copper plate having different thicknesses are joined to each other. As shown in FIG. 5A, the end portions of the thick aluminum plate 5 and the thin copper plate 7 ′ are joined to each other in a plane. Shall. As shown in FIG. 5B, the end face of the aluminum plate 5 to be joined is polished to form a joining surface 5b from which the oxide film on the surface has been removed. Also, the end portion of the copper plate 7 ′ is similarly polished to form a bonding surface 7′b from which the surface dirt and oxide film have been removed.

  Next, as shown in FIG. 5C, the polished joining surfaces 5b and 7'b are overlapped, and the dies 10a and 10b are arranged above and below. The upper die 10a and the lower die 10b have flat pressing surfaces as in the example of FIGS.

  Thereafter, as shown in FIG. 5D, a pressing force is applied to the upper and lower press-connecting dies 10a and 10b to cold-weld the joined portions. By this pressure welding, the joining surfaces 5b and 7'b are joined and integrated. At this time, the joining surfaces 5b and 7'b before joining are plastically deformed into an indefinite shape as shown by the joining end portions 5c and 7'c by pressure welding and are tightly joined. The remaining plate thickness after the pressure deformation at the center portion of the pressure contact is (a) on the aluminum plate 5 side and (b) on the copper plate 7 'side (a ≧ b), and the joining thickness (a + b) is Compressed and bonded to the thickness of a thick aluminum plate or below.

FIG. 6 is a diagram showing test results obtained by cold-welding an aluminum plate and a copper plate in the various forms described above, and the bonding state of samples 1 to 7 was examined. The test was performed by joining one short side of an aluminum plate (long side 50 mm, short side 10 mm) and a copper plate (long side 50 mm, short side 10 mm). In addition, the judgment criteria of the evaluation was “○” if the aluminum plate or the copper plate was lifted after being joined and lifted without peeling, and “X” if the other was peeled and not lifted. .
In addition, the residual thickness in the pressure-welded part after cold pressure welding is the value measured in the center part of pressure welding as demonstrated in FIGS. 3-5, (a) on the aluminum plate side, (b) on the copper plate side. The value in [] represents the residual ratio (= plate thickness after pressure welding / plate thickness before pressure welding × 100).

In Samples 1 and 2, the thicknesses of both the aluminum plate and the copper plate were set to 0.2 mm, and the edge portions were subjected to oblique shearing to remove oxide films and the like. The end portions were overlapped with each other in the form shown in FIG. 3, and a pressure stress of 8000 MPa was applied to Sample 1 and 3000 MPa was applied to Sample 2 by applying pressure stress to the pressure contact die.
As a result, the remaining thicknesses [residual ratios] a and b are as follows. Sample 1 has a = 0.05 mm [25%], b = 0.14 mm [70%], and Sample 2 has a = 0.06 mm [25%]. ], B = 0.14 mm [70%], and the bonding state was “◯” in both cases.

In Samples 3 and 4, the thickness of the aluminum plate was 0.4 mm, the thickness of the copper plate was 0.2 mm, and the end portion was obliquely sheared to remove the oxide film or the like. The end portions were overlapped with each other in the form shown in FIG. 4, and a pressure stress of 1000 MPa was applied to sample 3 and a pressure stress of 4000 MPa was applied to sample 4 and pressed.
As a result, the remaining thicknesses [residual ratios] a and b are as follows. Sample 3 has a = 0.26 mm [65%], b = 0.19 mm [95%], and Sample 4 has a = 0.25 mm [63%]. ], B = 0.17 mm [85%], and the bonding state was “◯” in both cases.

Samples 5 to 7 have an aluminum plate thickness of 0.4 mm and a copper plate thickness of 0.2 mm. Samples 5 and 6 have an oxide film or the like removed from the joint surface at the end as shown in FIG. However, Sample 7 was not treated. The joining surfaces were overlapped with each other in the form shown in FIG. 5, and a pressure stress of 16000 MPa was applied to the sample 5, 500 MPa to the sample 6, and 16000 MPa to the sample 7 by applying pressure stress to the pressure die.
As a result, the remaining thicknesses [residual ratios] a and b are as follows: sample 5 is a = 0.19 mm [48%], b = 0.18 mm [90%], and sample 6 is a = 0.30 mm [75%]. ], B = 0.19 mm [95%], sample 7 was a = 0.18 mm [45%], b = 0.18 mm [90%], and sample 5 had a bonding state of “◯”. However, Samples 6 and 7 were “x”.

From the above test results, as in sample 6, if the load stress applied to the pressure welding die is too small, insufficient pressure welding results in poor bonding. From the results of Sample 3, it is sufficient that the load stress is about 1000 Mpa. Above this, there is no significant difference in the remaining thickness due to the magnitude of the load stress. Further, from the result of the sample 7, it was found that when the oxide film or the like on the bonding surface was not removed and the oxide film remained, bonding failure occurred even when pressed with a large load stress.
Moreover, when the aluminum plate and the copper plate are cold-welded, the compression spread of soft aluminum is larger than that of copper, the remaining rate of the aluminum plate thickness (30 to 65%) is small, and the thickness of the copper plate The residual ratio (70 to 95%) was larger.

  From the above results, a pressure welding die with a flat pressing surface is used by removing the oxide film at the joining end portion on the aluminum plate side, dirt and plating layer on the copper plate side by joining by cold pressure welding of the aluminum plate and the copper plate. Thus, an aluminum lead with copper can be manufactured at low cost. Moreover, the increase in the thickness of the joined portion between the aluminum plate and the copper plate is sufficiently suppressed, so that the unevenness does not occur and the processing for compressing the thickness is not required.

DESCRIPTION OF SYMBOLS 1 ... Non-aqueous electrolyte battery, 2 ... Exterior body, 3 ... Aluminum lead, 4 ... Copper lead, 5 ... Aluminum plate, 5a, 5b ... Joining surface, 6 ... Insulating resin film, 6a ... Inner layer, 6b ... Outer layer, 7, 7 '... Copper plate, 7a-7'c ... Joining surface, 8 ... Electrode plate lead, 9 ... Protection circuit board, 10a, 10b ... Pressure welding die.

Claims (3)

A metal lead for a non-aqueous electrolyte device in which a copper plate is joined to one end portion of a rectangular aluminum plate by cold welding, and the joined portion is covered with an insulating resin film,
The joint portion is joined to the front Symbol copper plate in a state where oxide films of the bonding surface of the end portion of the aluminum plate has been removed, metal leads, characterized in that there are no irregularities in the joint portion. A method for producing a metal lead for a non-aqueous electrolyte device in which a copper plate is joined to one end portion of a rectangular aluminum plate by cold welding, and the joined portion is covered with an insulating resin film,
Metal, characterized in that bonding the bonding portion by the pressing surface flat crimping die pre Symbol copper plate after removing the oxide film of the bonding surface of the end portion of the aluminum plate, no irregularities in the joint portion Lead manufacturing method.   3. The method of manufacturing a metal lead according to claim 2, wherein the oxide film on the joint surface of the end portion of the aluminum plate is removed by polishing or oblique shearing.

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