Laser bonding apparatus and method

Abstract

The present invention relates to an apparatus and a method for bonding different materials without damage to a lower base material by using laser irradiation heat and a filler (solder or brazing) for bonding different materials during the manufacture of battery packs. The apparatus for bonding different materials, according to an embodiment of the present invention, comprises: an upper base material arrangement unit for arranging an upper base material at a bonding position; a lower base material arrangement unit for arranging, in an overlapped manner, such that the bonding position of the lower base material faces the bonding position of the upper base material; a bonding material injection unit for injecting, between the upper base material and the lower base material, a bonding material to be melted by conduction heat generated when the upper base material is heated; and a laser irradiation unit for heating the upper base material by irradiating the upper surface of the upper base material with a laser.

Description

Laser bonding device and method

[0001] The present invention relates to a laser bonding device and method between dissimilar materials, and more particularly, to a laser bonding device and method using laser irradiation heat and filler (solder or brazing) for bonding dissimilar materials during the manufacture of a battery pack.

[0002] With the increasing technological development and demand for mobile devices such as smartphones, laptops, and digital cameras, technology related to rechargeable secondary batteries is rapidly developing. Furthermore, secondary batteries are being used as an alternative energy source to fossil fuels, which contribute to air pollution, in electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (P-HEVs), and energy storage systems (ESS).

[0003] Currently, the types of secondary batteries widely used include lithium secondary batteries, nickel cadmium batteries, nickel hydrogen batteries, and nickel zinc batteries. In particular, research and development is actively being conducted on lithium secondary batteries, which have the advantages of high operating voltage and high energy density per unit weight.

[0004] However, lithium secondary batteries have the risk of overheating or explosion due to overcharging, overcurrent, or external impact.

[0005] Therefore, it is common to manufacture a battery pack by housing lithium secondary batteries in a housing to protect them from external impacts and including a protection circuit module (PCM) that can control overcharging or overcurrent.

[0006] In order to electrically connect the protection circuit module and the secondary battery, it is necessary to bond the electrode leads and the protection circuit module.

[0007] Various known welding methods can be used for this type of joining, but from the perspective of increasing productivity, etc., laser welding, especially pulsed laser welding using a Nd:YAG laser with an oscillation wavelength of approximately 0.5-1.1㎛, is mainly used recently.

[0008] Fig. 1 is a drawing for explaining a conventional method for bonding dissimilar materials using laser irradiation. At this time, Fig. 1(a) is a perspective view showing dissimilar materials arranged to be bonded using laser irradiation, and Fig. 1(b) is a cross-sectional view showing a bonding line portion of dissimilar materials bonded using laser irradiation.

[0009] Referring to Fig. 1, as illustrated in (a) of Fig. 1, the upper base material (10) and the lower base material (20) are placed so as to face each other at the joining line (A) and overlap each other, and then a laser (30) is irradiated to the upper surface of the upper base material (10) corresponding to the joining line (A). At this time, the laser (30) irradiated to the joining line (A) penetrates the upper base material (10) and is irradiated to the lower base material (20), thereby melting the upper base material (10) and the lower base material (20) together, thereby forming an alloy at the portion of the upper base material (10) and the lower base material (20) corresponding to the joining line (A), thereby performing joining between dissimilar materials.

[0010] In this way, the conventional method of joining dissimilar materials using laser irradiation is to use a laser (30) to melt the upper base material (10) and the lower base material (20) together and join them.

[0011] However, since the conventional method of joining dissimilar materials requires that the upper base material (10) be pierced and the lower base material (20) be melted due to the nature of laser welding, a hole may be created in the lower base material (20) if the laser intensity output control fails. In particular, when this problem occurs in a cylindrical battery cell, the piercing of the lower base material (20) may cause leakage. This may act as a factor in producing defective products.

[0012] Another conventional upper / lower base material laser joining method, as disclosed in the patent document (3) below, involves inserting a predetermined filler metal between the upper / lower base materials to be joined, melting the filler metal with the ambient heat generated during welding to join the gap created between the upper / lower base materials, thereby resolving the problem of the weld bead being formed narrow and deep and the joint not being formed over a wide area when only upper / lower base material melting welding is performed. However, this welding method also causes the same problem because welding is performed by melting the lower base material.

[0013] In this way, since the conventional method of joining dissimilar materials is a method of joining while damaging the lower base material (20), when joining dissimilar materials that must not be pierced by the lower base material (20), there is a problem that damage to the components below becomes serious if the lower base material (20) is pierced. In particular, since the output of the laser intensity varies depending on the material, thickness, etc. of the upper base material (10), it becomes more difficult to control and maintain the laser intensity to prevent damage to the components placed below the joining base materials.

[0014] The present invention aims to provide a laser bonding device and method that uses laser irradiation heat and filler (solder or brazing) to bond dissimilar materials during the manufacture of a battery pack without damaging the underlying base material.

[0015] The present invention provides a laser bonding device and method that uses conductive heat generated when heating an upper base material with a laser to melt (melt) filler (solder or brazing) located between an upper base material and a lower base material to bond dissimilar materials.

[0016] An embodiment of the present invention provides a new laser bonding device and method for bonding dissimilar materials by heating only the upper base material with a laser and using the heat generated therefrom to melt a separate bonding material located between the upper base material and the lower base material.

[0017] A dissimilar material joining device according to an embodiment of the present invention comprises: an upper base material placing unit for placing an upper base material at a joining position; a lower base material placing unit for placing the joining position of the lower base material so that it overlaps with the joining position of the upper base material so that it faces each other; a joining material injection unit for injecting a joining material that is melted by heat conduction generated when the upper base material is heated between the upper base material and the lower base material; and a laser irradiation unit for heating the upper base material by irradiating a laser to the upper surface of the upper base material.

[0018] The above upper substrate and the above lower substrate are heterogeneous materials having different materials.

[0019] The above bonding material is a material that melts by heat, and is characterized by being a metal or alloy having a lower melting point than the upper base material and the lower base material, and being a solder or brazing material.

[0020] The above laser irradiation unit is positioned directly above the upper base material so that the lower base material and the joint portion are overlapped and face each other, and irradiates the laser to the upper surface of the upper base material in the downward direction to heat and melt the upper base material.

[0021] The above laser irradiation unit controls the output of the laser irradiation so that the upper substrate is not penetrated by the laser.

[0022] The device further includes a temperature measuring unit positioned at least in one of the upper substrate and the lower substrate to measure the temperature of conductive heat generated from the upper substrate, and the laser irradiation unit controls the output of the laser irradiation so that the temperature of conductive heat generated from the upper substrate does not become higher than the melting point temperature of the lower substrate using the temperature measured by the temperature measuring unit.

[0023] Preferably, the sub-base material arrangement portion further includes a heat sink that dissipates heat from the sub-base material.

[0024] The above bonding material is melted by the conductive heat of the upper base material heated by laser irradiation, and is cooled by the heat sink to bond the upper base material and the lower base material.

[0025] A method for joining dissimilar materials according to an embodiment of the present invention comprises: a joining material application step of applying a joining material to a joining portion of a lower base material; an upper base material arrangement step of arranging an upper base material on top of the lower base material to be in contact with the joining material; a laser irradiation step of irradiating a laser to an upper surface of the upper base material; and a joining material melting step of melting the joining material by transferring conductive heat generated when the upper base material is heated by the laser irradiation to the lower surface of the upper base material.

[0026] The above laser irradiation step includes a step of controlling the output of the laser irradiation so that the upper substrate is not penetrated by the laser.

[0027] The above laser irradiation step includes a step of measuring, in a temperature measuring unit, the temperature of the conductive heat generated from at least one of the upper base material and the lower base material; and a step of controlling the output of the laser irradiation so that the temperature of the conductive heat generated from the upper base material does not become higher than the melting point temperature of the lower base material using the measured temperature.

[0028] The above-mentioned bonding material melting step includes a step of irradiating a laser of a predetermined output for a predetermined period of time until the bonding material is melted; and a step of cooling the bonding material so that the upper base material and the lower base material are bonded.

[0029] Preferably, the method for joining dissimilar materials further includes a step of dissipating heat from the lower portion of the lower substrate through a heat sink.

[0030] According to another embodiment of the present invention, a method for joining dissimilar materials comprises: a step of applying a joining material to prepare an upper or lower base material; a step of arranging base materials, wherein at least one of the upper and lower base materials, on which the joining material is applied, is arranged with the other base material so that the joining material is in contact with the other base material; a step of irradiating a laser with a predetermined output for a predetermined period of time until the joining material between the arranged base materials melts; and a step of cooling the joining material so that the upper and lower base materials are joined.

[0031] According to an embodiment of the present invention, by melting only the filler (solder or brazing) and using the heat generated by the laser to join dissimilar materials, the lower base material is not melted, so there is no damage to the lower base material, and the use of a low-power laser is possible. This has the effect of making it easy to control and maintain the laser intensity by utilizing the conductive heat of the upper base material, regardless of the type and thickness of the upper base material.

[0032] In addition, when manufacturing a battery pack, damage to the underlying material can be reduced, thereby preventing leakage of battery cells, which can have the effect of improving the stability of the secondary battery.

[0033] Figure 1 is a drawing for explaining a method for joining dissimilar materials using conventional laser irradiation.

[0034] Fig. 2 is a drawing showing the configuration of a laser bonding device according to an embodiment of the present invention.

[0035] Figure 3 is a flowchart for explaining a laser bonding method according to an embodiment of the present invention.

[0036] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. However, the present invention is not limited to the embodiments disclosed below and may be implemented in various different forms. These embodiments of the present invention are provided solely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention. For the purpose of explaining the invention in detail, the drawings may be exaggerated, and like reference numerals throughout the drawings represent like elements.

[0037] Fig. 2 is a drawing showing the configuration of a laser bonding device according to an embodiment of the present invention.

[0038] Referring to FIG. 2, a laser bonding device according to an embodiment of the present invention includes an upper base material (100) and a lower base material (200) that are arranged to overlap each other so that the bonding portions face each other, a bonding material (400) (410) positioned between the upper base material (100) and the lower base material (200) and melted by conductive heat generated when the upper base material (100) is heated, and a laser irradiation unit (300) that irradiates a laser to the upper surface of the upper base material (100) to heat the upper base material (100).

[0039] At this time, the upper substrate (100) and the lower substrate (200) may be dissimilar materials having different materials, such as battery cell electrodes and bus bars, and are materials to be joined to each other through laser welding. For example, the upper substrate (100) and the lower substrate (200) may be electrode leads and a protection circuit module used when electrically connecting a protection circuit module and a secondary battery, and may be electrode leads and a bus bar of a secondary battery.

[0040] In addition, the bonding material (400) is a material that melts by heat and may be a metal or alloy having a lower melting point than the upper base material (100) and lower base material (200) to be bonded, and may be solder or brazing, as an example.

[0041] And the laser irradiation unit (300) is positioned directly above the upper base material (100) so that the lower base material (200) and the joint area are overlapped and face each other, and irradiates the laser to the upper surface of the upper base material (100) in the downward direction. The laser irradiation unit (300) of the present invention heats the upper base material (100) and melts the joint material (400) with the heat conduction thereof, but is controlled so that the lower base material (200) is not melted.

[0042] Accordingly, the upper base material (100) irradiated with the laser of the laser irradiation unit (300) can be melted (110) to a predetermined thickness at the upper portion. In addition, the conductive heat generated when the upper base material (100) is heated is transferred to the lower surface of the upper base material (100), thereby melting (410) the bonding material (400) located at the lower portion of the upper base material (100). At this time, the laser irradiation unit (300) controls the output of the laser irradiation so that the upper base material (100) is not penetrated by the laser.

[0043] To this end, the laser bonding device according to the present invention may further include a temperature measuring unit (not shown) positioned on at least one of the upper base material (100) and the lower base material (200) to measure the temperature of the conductive heat generated from the upper base material (100). The laser irradiation unit (200) can control the output of the laser irradiation using the temperature measured by the temperature measuring unit so that the temperature of the conductive heat generated from the upper base material (100) does not become higher than the melting point temperature of the lower base material (200). The measured temperature data is fed back to the control system of the laser irradiation unit (300) to control the output of the laser irradiation, thereby preventing damage to the lower base material due to overheating.

[0044] Meanwhile, the laser bonding device according to the embodiment of the present invention can irradiate a laser of a predetermined output for a predetermined period of time until the bonding material (400) positioned between the upper base material (100) and the lower base material (200) is melted, and then cool the bonding material (400) so that the upper base material (100) and the lower base material (200) are bonded.

[0045] In addition, although not shown in the drawings, the laser bonding device according to an embodiment of the present invention may further include an upper base material placement unit for placing the upper base material (100) at a bonding position, a lower base material placement unit for placing the lower base material (200) at the bonding position, a bonding material injection unit for injecting a bonding material (400) into the bonding portion of the lower base material (200), and a bonding base on which the lower base material (200) is placed and placed.

[0046] The bonding base may further include a heat sink (not shown) that comes into contact with the lower base material (200) placed on top and dissipates heat from the lower base material (200). The heat sink is configured to dissipate heat that is transferred to the lower base material (200) in excess of what is necessary when the lower base material (200) is placed on top of the bonding base. When the laser irradiation unit (300) heats the upper base material (100), the bonding material (400) is melted, but additional heat is prevented from being transferred to the lower base material (200) and the lower base material (200) is melted. In addition, the heat sink provided in the lower base material placement unit prevents excessive heat from accumulating in the lower base material.

[0047] Hereinafter, a laser bonding method according to an embodiment of the present invention will be described. The laser bonding method according to an embodiment of the present invention may be a method of processing using the aforementioned laser bonding device. Accordingly, the above-described content regarding the laser bonding device can be applied as is, and therefore, a description of redundant content may be omitted.

[0048] Figure 3 is a flowchart for explaining a laser bonding method according to an embodiment of the present invention.

[0049] Referring to FIG. 3, a laser bonding method according to an embodiment of the present invention places a lower base material (200) on a bonding base, and then applies a bonding material (400) to the bonding portion of the lower base material (100) (S10). At this time, the bonding material (400) may be injected into the bonding portion of the lower base material (200) through a bonding material injection port. The applied bonding material (400) is a material that melts by heat, and may be a metal or alloy having a lower melting point than the upper base material (100) and the lower base material (200). As an example, it may be solder or brazing.

[0050] Next, after placing the lower base material (200) at the joint position through the lower base material placement section, the upper base material (100) is placed on top of the lower base material (200) to which the jointing material (400) has been applied so as to be in contact with the jointing material (400) (S20).

[0051] And, by irradiating a laser to the upper surface of the upper base material (100) through the laser irradiation unit (300), the upper base material (100) is heated (S30). The laser irradiation unit (300) is positioned directly above the upper base material (100) so that the joint portions with the lower base material (200) are overlapped and face each other, and irradiates a laser to the upper surface of the upper base material (100) in the downward direction, thereby heating and melting the upper base material (100). And, the laser irradiation unit (300) controls the output of the laser irradiation so that the upper base material (100) is not transmitted by the laser. To this end, the temperature of at least one of the upper base material (100) and the lower base material (200) can be measured through the temperature measuring unit, and the output of the laser irradiation can be controlled so that the measured temperature does not become higher than the melting point temperature of the lower base material (200).

[0052] Accordingly, the conductive heat generated when the upper base material (100) is heated is transferred to the lower surface of the upper base material (100), melting (410) the bonding material (400) located under the upper base material (100), thereby bonding the upper base material (100) and the lower base material (200) to each other (S40). In addition, by controlling the output of the laser irradiation so as not to be higher than the melting point temperature of the lower base material (200), the lower base material (200) can be prevented from melting.

[0053] At this time, the S40 step may irradiate a laser of a predetermined output for a predetermined period of time until the bonding material (400) positioned between the upper base material (100) and the lower base material (200) is melted, and then the bonding material (400) may be cooled through a heat sink so that the upper base material (100) and the lower base material (200) are bonded. The heat sink is configured to dissipate heat that is transferred to the lower base material (200) in excess of what is necessary when the lower base material (200) is placed and raised on the bonding base, and when the laser irradiation unit (300) heats the upper base material (100), the bonding material (400) is melted, but additional heat is prevented from being transferred to the lower base material (200) and the lower base material (200) is melted.

[0054] While the preferred embodiments of the present invention have been described and illustrated using specific terms above, such terms are solely for the purpose of clearly describing the present invention, and it is to be understood that various modifications and variations may be made to the embodiments and terms described herein without departing from the spirit and scope of the appended claims. Such modified embodiments should not be construed individually from the spirit and scope of the present invention, but should be considered to fall within the scope of the claims.

Claims

1. Upper base material placement section for placing the upper base material at the joint location; A lower base material arrangement section in which the joint position of the lower base material is arranged to overlap with the joint position of the upper base material so that they face each other; A bonding material injection unit that injects a bonding material that is melted by conductive heat generated when the upper base material is heated between the upper base material and the lower base material; A laser bonding device including a laser irradiation unit that irradiates a laser to the upper surface of the upper substrate to heat the upper substrate.

2. In paragraph 1, A laser bonding device in which the upper and lower substrates are made of different materials.

3. In paragraph 1, A laser bonding device characterized in that the above bonding material is a material that melts by heat, is a metal or alloy having a lower melting point than the upper base material and the lower base material, and is a solder or brazing material.

4. In paragraph 1, The laser irradiation unit is positioned directly above the upper base material so that the lower base material and the joining portion are overlapped and face each other, and is a laser bonding device that irradiates a laser to the upper surface of the upper base material in a downward direction to heat and melt the upper base material.

5. In paragraph 4, The above laser irradiation unit is a laser bonding device that controls the output of the laser irradiation so that the upper substrate is not penetrated by the laser.

6. In paragraph 5, Further comprising a temperature measuring unit positioned at least in one of the upper and lower substrates to measure the temperature of the heat conduction generated in the upper substrate, The above laser irradiation unit is a laser bonding device that controls the output of the laser irradiation so that the temperature of the heat conduction generated from the upper base material does not become higher than the melting point temperature of the lower base material by using the temperature measured by the temperature measuring unit.

7. In paragraph 1, The above sub-material arrangement part is, A laser bonding device further comprising a heat sink that dissipates heat from the above-described sub-material.

8. In paragraph 7, A laser bonding device that bonds the upper and lower base materials by melting the above bonding material through the conductive heat of the upper base material heated by laser irradiation and cooling it through heat dissipation by the heat sink.

9. A step of applying a bonding agent to the joint area of ​​the lower part; An upper substrate placement step of placing an upper substrate on top of the lower substrate to which the above bonding material has been applied so as to be in contact with the bonding material; A laser irradiation step of irradiating a laser onto the upper surface of the upper substrate; and A laser bonding method including a bonding material melting step in which conductive heat generated when the upper base material is heated by the laser irradiation is transferred to the lower surface of the upper base material to melt the bonding material.

10. In paragraph 9, A laser bonding method, wherein the laser irradiation step includes a step of controlling the output of the laser irradiation so that the upper substrate is not penetrated by the laser.

11. In paragraph 10, The above laser irradiation step is, In a temperature measuring unit, a step of measuring the temperature of conductive heat generated from at least one of the upper substrate and the lower substrate; and A laser bonding method comprising a step of controlling the output of laser irradiation so that the temperature of the heat conduction generated from the upper base material does not become higher than the melting point temperature of the lower base material using the temperature measured above.

12. In paragraph 9, The above-mentioned bonding material melting step is, A step of irradiating a laser of a predetermined output for a predetermined period of time until the above-mentioned bonding material is melted; and A laser bonding method comprising a step of cooling the bonding material so that the upper base material and the lower base material are bonded.

13. In paragraph 9, The above dissimilar material bonding method is, A laser bonding method further comprising a step of dissipating heat from the lower portion of the substrate through a heat sink.

14. A step of applying a bonding agent to prepare the upper or lower base material; A base material arrangement step of arranging one of the upper base material and the lower base material, on which at least one bonding agent is applied, and the other base material so that the bonding agent is in contact with the other base material; A laser irradiation step of irradiating a laser of a predetermined output for a predetermined period of time until the bonding material between the arranged parent materials is melted; and A laser bonding method including a cooling step of cooling the above bonding material so that the upper base material and the lower base material are bonded.

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