JP2022518132A - Methods and systems for welding copper and other metals using a blue laser - Google Patents

Abstract

Visible light laser system and operation for welding materials together. A blue laser system that forms an essentially perfect weld on copper-based materials. Blue laser system and operation for welding conductive elements, especially thin conductive elements together, for use in energy storage devices such as battery packs. [Selection diagram] None

Description

This application claims the benefit of the filing date of U.S. Provisional Patent Application No. 62 / 786,511 filed on December 30, 2018 under Article 119 (e) (1) of the U.S. Patent Act, the entire disclosure thereof. Is incorporated herein by reference.

The present invention relates to laser processing of materials, in particular laser bonding of copper materials using a laser beam having wavelengths from about 350 nm to about 500 nm and above.

Laser welding of copper has proven to be very difficult due to its high reflectance, high thermal conductivity, and high heat capacity. Many methods have been developed for welding copper, from ultrasonic welding to IR laser welding. However, these conventional copper welding methods have many drawbacks and limitations. For example, one market where these limitations are found is in the field of high performance electronics for the growing electric vehicle market. Manufacturing high-performance batteries and electronic devices for the growing automotive market requires faster and better welding quality than can be achieved with these traditional technologies.

When using an IR laser light source at 1030 nm, the high reflectance of copper at this wavelength makes it difficult to bind power to the material and heat and weld it. One way to overcome high reflectance is to initiate keyhole welding using a high power level (> 1 kW) IR laser, thereby binding power to the material. The problem with this welding method is, among other things, that the steam in the keyhole causes a micro-explosion that sprays molten copper over the entire welded part or opens a hole that completely penetrates the part to be welded by the micro-explosion. There is a possibility that it will happen. As a result, researchers have to rely on rapid modulation of laser power to prevent these defects during welding. It turns out that these defects are a direct result of the process itself, as when trying to weld copper with a laser, the laser first heats the copper to its melting point and then rapidly transitions to copper vaporization. There is. As the copper vaporizes to form keyholes and the laser coupling rises rapidly from the initial 5% to 100%, this transition occurs so rapidly that the amount of heat combined is the amount of heat required to weld the part. Rapidly exceeds, resulting in the micro-explosion described above.

Laser welding of copper using current infrared laser methods and systems is difficult and has problems due to its high reflectance, high thermal conductivity, low vaporization point, and high heat capacity. Attempts have been made to weld copper with IR lasers in a variety of ways, including combinations of IR lasers and green lasers, spot wobbling in molten pools, vacuum operations, and high frequency laser modulation. These approaches are currently used in some copper welding applications, but have been found to be generally desirable or unoptimal due to the narrow process window, uncontrolled spatter, and unpredictable welding variability. ing. One of the more difficult copper welding processes is the method of welding copper foil laminates (stacked copper foils) to each other and to thicker busbars. Today, this cannot be done reliably with IR lasers or in a way that produces the weld quality required by the manufacturer. For this reason, manufacturers have relied on ultrasonic welding methods to bond these foils together. These ultrasonic methods are also not optimal and have problems. For example, in ultrasonic welding, sonotrod can wear during manufacturing, resulting in process variability from incomplete welds to welds that leave debris. These defects limit manufacturing yield, limit the internal resistance of the battery, limit the resulting energy density of the battery, and often limit the reliability of the battery.

The term "copper-based material" should be given as broadly as possible, unless otherwise stated, copper, copper material, copper metal, copper electroplated material, at least about 10% to 100 weight. Metallic materials containing% copper, metals and alloys containing at least about 10% to 100% by weight copper, metals and alloys containing at least about 20% to 100% by weight copper, at least about 10% to 100% by weight. From metals and alloys containing% copper, metals and alloys containing at least about 50% to 100% by weight copper, metals and alloys containing at least about 70% to 100% by weight copper, and from at least about 90% by weight. Includes metals and alloys containing 100% by weight copper.

The terms "laser processing", "laser processing of materials", and similar such terms should be given the broadest possible meaning, unless otherwise specified, welding, soldering, smelting, joining, etc. Includes annealing, softening, tacking, resurfacing, peening, heat treatment, fusion, sealing and stacking.

As used herein, unless otherwise stated, "UV", "ultraviolet", "UV spectrum", and "UV portion of spectrum" and similar terms should be given their broadest meaning. Yes, it contains light with wavelengths from about 10 nm to about 400 nm, and from 10 nm to 400 nm.

As used herein, unless otherwise stated, the terms "visible," "visible spectrum," and "visible portion of the spectrum" and similar terms should be given their broadest meaning. Includes light with wavelengths from about 380 nm to about 750 nm, and 400 nm to 700 nm.

As used herein, unless otherwise stated, the terms "blue laser beam", "blue laser" and "blue" should be given their broadest meaning and generally provide a laser beam. Refers to a system, a laser beam, a laser beam having a wavelength of about 400 nm to about 500 nm or a laser source such as a propagating laser beam or light such as a laser and a diode laser. The wavelength of a typical blue laser is in the range of about 405-495 nm. The blue laser includes wavelengths of 450 nm, about 450 nm, 460 nm, and about 470 nm. Blue lasers have bandwidths from about 10 pm (picometers) to about 10 nm, about 5 nm, about 10 nm, about 20 nm, and larger and smaller values.

As used herein, unless otherwise stated, the terms "green laser beam", "green laser" and "green" should be given their broadest meaning and generally provide a laser beam. Refers to a system, a laser beam, a laser beam or light having a wavelength of about 500 nm to about 575 nm, such as a propagating laser and a laser source such as a diode laser. The green laser includes wavelengths of 515 nm, about 515 nm, 532 nm, about 532 nm, 550 nm, and about 550 nm. Green lasers have bandwidths of about 10 pm to 10 nm, about 5 nm, about 10 nm, and about 20 nm, and larger and smaller values.

As used herein, terms such as "at least" and "greater than" also mean "greater than or equal to" unless otherwise stated, i.e. such terms are lower values unless otherwise stated. Exclude.

In the present specification, the room temperature is 25 ° C. unless otherwise specified. The standard temperature and standard pressure are 25 ° C. and 1 atm. Unless otherwise stated, all tests, test results, physical properties, and temperature-dependent, pressure-dependent, or both values are provided at standard temperature and standard pressure.

In general, the term "about" and the symbol "~" as used herein are of ± 10% variance or range, of any experiment or instrument associated with obtaining the stated values, unless otherwise stated. Includes errors, and preferably the larger of these.

As used herein, unless otherwise stated, a range of values, a range from about "x" to about "y", and similar terms and quantifications are separate values within that range. It is just a way to omit referencing individually. Therefore, they include each item, function, value, quantity, or quantity within that range. As used herein, unless otherwise stated, all individual points within the scope are incorporated herein and are part of this specification as if they were described individually herein. Make.

The description of this background art of the invention is intended to introduce various aspects of the art that may be relevant to embodiments of the invention. Therefore, the above description in this description provides a framework for a better understanding of the invention and should not be considered as a prior art approval.

Continuously and for better welding quality, faster welding, and better reproducibility, reliability, higher tolerances and higher robustness in metal welding, especially copper metal welding for electronic components and batteries. There are increasing needs. Included in these needs is the need for improved methods for welding copper to itself and other metals. Then there is a need to address the problems associated with welding copper foil laminates and welding these laminates to thicker copper or aluminum parts. The present invention, among other things, solves these needs by providing the improvements, manufactured goods, devices and processes taught and disclosed herein.

The present invention is a method of laser welding a plurality of copper foils together, in which a plurality of copper foils containing at least about 50% copper are placed on a welding stand; a clamping force is applied to the plurality of copper foils. A step of clamping copper foils together in a welding stand; a step of directing a blue laser beam to multiple copper foils along a laser beam path, wherein the laser beam is (i) at least 500 watts of power :( ii) Has the characteristics of a beam parameter product of about 44 mmrad or less, (iii) a spot size of about 400 μm or less, (iv) an average intensity of at least about 400 kW / cm ² , and (v) a peak intensity of at least about 800 kW / cm ² . Then, the blue laser beam is configured to superimpose and weld the plurality of copper foils at a certain welding speed; (e) The laser beam path in which the laser beam travels in free space from the optical element to the plurality of copper foils. In the space along, there is a step of removing plume material from the laser beam path and providing a non-oxidizing clearing gas that prevents oxidation of multiple copper foils; the welding speed, the clamping force, and the non-oxidation. The flow rate of the sex beam clearing gas provides a method that is configured to be pre-determined to provide lap welding without visible spatter and visible porosity.

Further, these welds, laser systems, and weld methods have one or more of the following features: That is, the beam is a CW beam; the beam is a pulse beam; the beam has a wavelength of about 450 nm; the optics are selected from the group consisting of lenses, fiber surfaces, and windows; the clearing gas is argon. , Argon-CO ₂ , selected from the group consisting of air, helium, and nitrogen; the laser beam is not wobbled and a wobble-free laser welding process is provided; multiple copper foils are 10 to 50 pieces of copper. It has a foil; the copper foil has a thickness of about 80 μm to 500 μm; each of the plurality of copper foils has a thickness of about 80 μm to 500 μm; the welding speed is at least 10 m / min.

Further, a system and a method for laser welding a plurality of metal pieces together are provided, in which the method is a step of placing the plurality of metal pieces in a welding stand; a clamping force is applied to the plurality of metal pieces to apply the welding force. A step of clamping the pieces of metal together in a stand; a step of directing a blue laser beam toward the pieces of metal along a laser beam path, wherein the laser beam is (i) at least 500 watts of power, (ii). ) Beam parameter product of about 44 mm mad or less, (iii) spot size of about 400 μm or less, (iv) average intensity of at least about 400 kW / cm ² ; (v) having peak intensity characteristics of at least about 800 kW / cm ² . The blue laser beam is adapted to weld the plurality of metal pieces together at one welding rate: a laser beam path through which the blue laser beam travels in free space from an optical element to a plurality of copper foils. In the space along, there is a step of providing a non-oxidizing beam clearing gas that removes plume material from the laser beam path and prevents oxidation of multiple copper foils; the welding speed, the clamping force, and the non-welding. The flow rate of the oxidative clearing gas is predetermined to provide a weld with no visible spatter and no visible porosity.

In addition, these welds, laser systems, and weld methods have one or more of the following features: That is, the welding stand has an air gap under the piece of metal; the metal consists of aluminum, stainless steel, copper, aluminum-based metal, stainless steel-based metal, copper-based metal, aluminum alloy, stainless steel alloy and copper alloy. Selected from the group; the laser beam has a wavelength of about 450 nm; the laser beam is wobbling-free, thereby providing a wobbling-free laser welding process; welding is lap welding, butt welding, bead-on-plate welding, And selected from a group of welds consisting of conduction mode welds.

Further provided are systems and methods of laser welding multiple copper foils together, the method placing multiple copper foils containing at least about 50% copper and having a thickness of about 80 μm to 500 μm on a welding stand. Step; A step of applying a clamping force to the plurality of copper foils to clamp the copper foils together in the welding stand; a step of directing a blue laser beam toward the plurality of copper foils along a laser beam path. The laser beam has (i) a power of at least 600 watts, (ii) a beam parameter product of about 44 mm mad or less, (iii) a spot size of about 200 μm to about 400 μm, and (iv) at least about 2.1 MW / cm ² . It has characteristics of average intensity, (v) peak intensity close to at least about 4.5 MW / cm2, and the blue laser beam is adapted to weld the plurality of metal pieces together at a welding rate of at least 10 m / min. Steps; In the space along the laser beam path where the laser beam travels in free space from the optical element to the plurality of copper foils, the plume material is removed from the laser beam path to prevent oxidation of the plurality of copper foils. To provide a non-oxidizing beam clearing gas; the welding speed, clamping force, and flow rate of the non-oxidizing clearing gas do not have visible spatter and visible porosity. It is made to be pre-determined to provide welding.

Also provided is a method of forming a complete weld on the copper-based material, which is the step of placing a workpiece containing the first copper-based material in contact with the second copper-based material in the laser system. A step of directing a blue laser beam at the workpiece to form a weld between the first piece of copper-based material and the second piece of copper-based material; The portion contains a HAZ and a resolidification region, and the copper-based material, the HAZ, and the microstructure of the resolidification region are made to be the same.

Further provided are these welds, systems, and methods having one or more of the following features: That is, the same microstructure does not show identifiable differences in the weld that may indicate weld fragility; the same microstructure contains crystal growth regions of similar size; the weld is in conduction mode. It is formed by welding; the weld is formed by keyhole mode welding; the first and second pieces have a thickness of about 10 μm to about 500 μm; the first piece is a plurality of copper foils. The first part is a copper metal; the first piece is a copper alloy with about 10 to about 95 weight percent of copper; the laser beam has a power density of less than 800 kW / cm ² . Is directed at the workpiece as a focused spot; the laser beam is directed at the workpiece as a focused spot with a power density of less than 500 kW / cm ² ; the laser beam is directed at about 100 kW / cm ² to about 800 kW / cm ² . Directed to the workpiece as a focused spot with power density; the laser beam is directed to the workpiece as a focused spot with a power density greater than 100 kW / cm ² ; the laser beam has a power of less than 500 W; the laser beam is less than 275 W. The laser beam has a power of less than 150 W; the laser beam has a power in the range of 150 W to about 750 W; the laser beam has a power in the range of about 200 W to about 500 W; the laser beam has a power of about 200 W to about 500 W. Directed to the workpiece as focused spots with a spot size of about 50 μm to about 250 μm; the laser beam has a wavelength of about 405 nm to about 500 nm; welds are formed without spatter; the laser does not evaporate the workpiece ..

Further, a method of forming a complete weld on a copper-based material, the step of placing the first copper-based material piece in a laser system so as to be in contact with the second copper-based material piece; It has a step of directing a blue laser beam at the workpiece, thereby forming a weld between a piece of copper-based material and a piece of copper-based material of the second; the weld. Provided is a method of forming a complete weld in a copper-based material, comprising the HAZ and a resolidification region, the hardness range of the HAZ being set to be within the hardness range of the copper-based material.

Further provided are these welds, systems, and methods having one or more of the following features: That is, the hardness range of the resolidification region is within the hardness range of the copper-based material; the microstructure of the copper-based material, HAZ and the resolidification region is the same; the same microstructure is the fragility of the weld. Does not show identifiable differences in welds that may indicate sex; the same microstructure does not show identifiable differences in welds that may indicate vulnerability in welds; said identical microstructure. Includes a crystal growth region of similar size.

In addition, a workpiece containing a piece of the first copper material that is in contact with the piece of the second copper material, which is a method of forming a complete weld on the copper material, is placed in the laser system. Steps to: Direct the blue laser beam at the workpiece, thereby having a step of forming a weld between the first copper-based material piece and the second copper-based material piece. A method of forming a complete weld on a copper-based material is provided such that the weld includes the HAZ and the resolidification region and the hardness range of the resolidification region is within the hardness range of the copper-based material.

Further provided are the welding of copper using a blue laser having a wavelength range of 405 nm to 500 nm, and the welds and products formed by this weld.

In addition, these welds, methods, and systems are provided that include one or more of the following features: That is, weld copper in conduction mode; weld copper in conduction mode without vaporization of the molten pool during the welding process; weld copper in conduction mode with a crystal growth region similar in size to the base metal. Form a microstructure similar to the base metal; weld copper as in conduction mode to form a microstructure similar to the base metal in the heat affected area (HAZ); weld copper in conduction mode, Form a microstructure similar to the base metal in the weld bead; weld copper in conduction mode to produce the same hardness as the base metal in the heat affected area; weld copper in conduction mode into the weld bead Produces hardness similar to the base metal; welds copper to make the microstructure of the weld different from the base metal; welds copper to make the microstructure in the HAZ similar to the base metal.

In addition, these welds, methods, and systems are provided that include one or more of the following features: That is, weld copper in keyhole mode; weld copper in keyhole mode so that very low spatter occurs during welding and little or no spatter is observed on the surface of the copper after welding; power density. Welds copper at a welding speed of 500 kW / cm ² or higher that allows the keyhole to remain open; a welding speed that allows the keyhole to remain open at a power density of 400 kW / cm ² or higher. Weld copper with; at a power density of 100 kW / cm ² or higher, the welding speed is fast enough to prevent the transition to the keyhole welding method; to improve the penetration depth during welding. Preheat to weld copper; weld copper with Ar-CO ₂ assist gas; weld copper with Ar-H ₂ assist gas; weld copper with Ar assist gas; with air Weld copper; Weld copper with He assist gas; Weld copper with N ₂ assist gas; Weld copper with assist gas.

In addition, these welds, methods, and systems are provided that include one or more of the following features: That is, the laser power is modulated from 1 Hz to 1 kHz; the laser power is modulated from 1 kHz to 50 kHz; the elongated blue laser spot is used to keep the keyhole open; the robot is used to quickly spot the spot. Move in a circular, vibrating, or rectangular vibrating motion; use a mirror attached to the galvanometer to vibrate the spot parallel to the welding direction; use a mirror attached to the galvanometer Vibrate the spot perpendicular to the welding direction; use a pair of mirrors attached to a pair of galvanometers to quickly move the spot in a circular, vibrating, or rectangular vibrating motion.

In addition, a method of forming a keyhole weld in a copper-based material is provided, in which the workpiece is laser systemized so that a piece of the first copper-based material is in contact with a piece of the second copper-based material. A keyhole containing a HAZ and a resolidification region between a piece of the first copper-based material and a piece of the second copper-based material with a blue laser beam directed at the workpiece. Includes steps to form welds in the mode.

In addition, these welds, methods, and systems are provided that include one or more of the following features: That is, the laser power of the keyhole weld is less than 1000 kW; the laser power of the keyhole weld is less than 500 kW; the laser power of the keyhole weld is less than 300 kW; the laser beam to suppress spatter from the keyhole. Stretches; Modulates the laser power to suppress spatter from the keyhole; Rapidly scans the beam to suppress spatter in the keyhole mode of the weld; After the weld is started automatically or manually Rapidly reduce laser power; use low atmospheric pressure to reduce gas and spatter trapped during the welding process; apply shield gas; shield gas selected from the group He, Ar, N ₂ Apply; Apply a shield gas mixture selected from the group consisting of Ar-H ₂ , N ₂ , N ₂ -H ₂ ; Apply a shield gas and add hydrogen to the shield gas to remove the oxide layer. And promotes wetting of welds.

It is a photograph of the embodiment of the conduction mode welded portion of copper without spatter according to the present invention.

It is a photograph of the embodiment of the copper keyhole welded portion according to the present invention.

It is a chart showing the relationship between the penetration depth and the velocity in the embodiment of the present invention with respect to copper having a thickness of 127 μm, and copper is completely melted up to a velocity of 8 m / min.

It is a chart showing the relationship between the penetration depth and the velocity in the embodiment of the present invention with respect to copper having a thickness of 254 μm, and copper is completely melted at a velocity of 0.5 to 0.75 m / min.

It is a chart which shows the relationship between the penetration depth and the velocity in embodiment of this invention.

It is a chart which shows the penetration depth at several different rates in embodiment of this invention.

FIG. 3 is an annotated photograph showing an embodiment of a conduction mode weld on a 70 μm thick copper foil according to the present invention.

It is a photograph with annotation of the cross section of the keyhole mode welded part by this invention.

Absorption curves of various metals, showing the difference in absorption between IR and visible lasers.

It is a schematic diagram of an embodiment of conduction mode welding propagation to a material according to the present invention.

It is a schematic diagram of the embodiment of the keyhole welding propagation to a material according to the present invention.

It is a perspective view of one Embodiment of the component holder for laser welding by this invention.

It is sectional drawing of the component holder of FIG.

It is a perspective view of the embodiment of the component holder for holding a thin component for performing lap welding according to the present invention.

It is sectional drawing of the component holder of FIG.

It is a photograph of a bead on a plate for conduction mode welding according to the present invention.

It is a photograph of the laminated body of the foil welded in the conduction welding mode by this invention.

It is a photograph of a bead on a plate for keyhole mode welding according to the present invention.

It is a photograph of the embodiment of the laminated body of 40 copper foils welded in the keyhole mode according to the present invention.

It is a graph of the penetration depth of copper for various power levels and various speed embodiments according to the present invention.

It is a schematic diagram of an embodiment of a 150 watt blue laser system for use in carrying out an embodiment of the laser welding method according to the embodiment of the present invention.

FIG. 6 is a schematic diagram of ray tracing of an embodiment using two 150 watt blue laser systems to make a 300 watt blue laser system according to the present invention.

FIG. 6 is a schematic diagram of ray tracing of an embodiment using four 150 watt blue laser systems to make an 800 watt blue laser system according to the present invention.

Beam caustic radius (micron (μm)) and displacement from focus of the embodiment when using a 100 mm focal length lens at 600 W for a circular aperture with 95% enclosed power according to the present invention. It is a graph of the relationship of (μm).

6 is a graph of an embodiment of a copper 110 bead (BOP) test on a plate showing the relationship between penetration (μm) and speed m / min according to the present invention.

It is a graph of the embodiment of the butt welding test of copper 110 which shows the relationship between the penetration (μm) and the speed m / min by this invention.

It is a graph of the embodiment of conduction mode welding by this invention, and shows the influence of the plate thickness on the penetration depth.

It is a graph of the BOP test embodiment of aluminum 1100 by this invention, and shows the relationship between the penetration (μm) and the speed m / min.

It is a graph of the BOP test embodiment of aluminum 1100 by this invention, and shows the relationship between the penetration (μm) and the speed m / min.

It is a graph of the BOP test embodiment of the stainless steel 304 according to the present invention, and shows the relationship between the penetration (μm) and the speed m / min.

It is a photograph of an embodiment of a longitudinal cross section of a plate of keyhole welded copper 110, showing the start of a complete penetration region.

FIG. 3 is a photograph of an embodiment of 1.016 mm thick copper welded at 1.1 m / min with minimal porosity and spatter according to the present invention.

It is a graph which shows the relationship between the penetration depth (μm) and the velocity (m / min) of the BOP test embodiment of the copper 110 welded with the spot size of 200 μm at 600 watts by this invention.

It is a photograph of the embodiment of the keyhole lap welding of four stainless steel 304s according to the present invention.

It is a graph of embodiment of the lap welding test with respect to the laminated body of the foil of copper 110 by this invention.

FIG. 5 is a photograph of an embodiment of a laminate of 40 copper 110 foils with a thickness of 10 μm welded with a 500 watt, 400 μm spot blue laser according to the present invention.

The present invention generally relates to metals, in particular aluminum, stainless steel, copper, aluminum-based metals, stainless steel-based metals, copper-based metals, and lasers, laser beams, systems and methods for welding these alloys. The present invention further generally assists in the welding process by introducing a method of applying a laser beam, beam size, beam power, a method of holding a part (part to be welded), and a shield gas, eg, preventing oxidation of the part. It also relates to how plume management prevents the plume from interfering with the laser beam.

In one embodiment, the invention provides high quality welds, high weld speeds, or both to copper-based materials in many areas including electronic components and further including batteries. In one embodiment, the invention provides high quality welds, high weld speeds, or both for copper-based materials in automotive components, including automotive electronic components, including batteries.

In one embodiment, the invention provides high quality welds, high weld speeds, or both for stainless steel materials in many areas including electronic components and further including batteries. In one embodiment, the present invention provides high quality welds, high weld speeds, or both to stainless steel-based materials in automotive components, including automotive electronic components, including batteries.

In one embodiment, the invention provides high quality welds, high weld speeds, or both for aluminum-based materials in many areas including electronic components and further including batteries. In one embodiment, the present invention provides high quality welds, high weld speeds, or both for aluminum-based materials in automotive parts including automotive electronic components including batteries.

In one embodiment of the invention, a high power blue laser light source (eg, about 450 nm) solves the problems of conventional copper welding techniques. The blue laser light source has a copper absorptance of about ~ 65% and provides a blue laser beam at wavelengths at which laser power can be efficiently coupled to the material at all power levels. This system and method provides stable welding in many welding techniques, including conduction mode and keyhole welding mode. This system and method minimizes, reduces, and preferably eliminates vaporization, spatter, microexplosions, and combinations and variations thereof.

In one embodiment, copper blue laser welding at power levels ranging from 150 watts to 275 watts with a spot size of about 200 μm or less achieves stable low spatter welding over the entire power range. In one embodiment of this welding system and method, welding is in conduction mode and the resulting weld microstructure resembles a base metal.

Preferably, in embodiments, the laser wavelength can be from 350 nm to 500 nm, and the spot size (diameter, or cross section) can range from 100 microns (μm) to 3 mm, with larger spot sizes as well. Also planned. The spot can be circular, elliptical, linear, square, or any other pattern. Preferably, the laser beam is continuous. In embodiments, the laser beam can be, for example, a pulse of about 1 microsecond or longer.

FIG. 6 shows the relationship between penetration depth and power at various welding speeds. This weld was performed using the type of system described in Example 1 (discussed below). Welding was performed on 500 μm copper with a power of 275 W for the laser beam, without assist gas.

The photograph of FIG. 7 shows a conduction mode welded portion in a copper foil having a thickness of 70 μm, and shows the microstructure of the HAZ (heat-affected zone) and the welded portion. This weld was made using the parameters described in Example 1. The penetration depth of each sample was determined by first cutting the sample and then etching the sample to reveal the microstructure of the weld and HAZ regions. Further, one of the samples was cross-sectioned, but the Vickers hardness of the entire base metal was in the range of 133-141 HV, the weld bead was in the range of about 135 HV, and the HAZ was in the range of 118-132 HV. The conclusion is that the hardness of the base metal HAZ and the weld bead (resolidification region, etc.) is close to that of the base metal. Moreover, the microstructures of the conduction mode weld beads, HAZ, and base metal are very similar, with slight differences. Welds with these properties have never been observed when copper is welded by laser or other means. This welding quality is shown in FIG. 7, in which the welded portion of the sample is cut in the transverse direction and etched to clarify the microstructure.

As described above, the embodiment of the present invention includes a method of welding a copper-based material in order to obtain the following welded portion, and the resulting welded portion itself. These methods and welds include welding two or more copper-based materials together, and in the area surrounding the weld, approved and established hardness tests (such as Vickers hardness, ASTM test, etc.) The hardness of the material (measured in) is that the hardness of the weld bead is within the hardness of the base metal, the hardness of the weld bead is within 1% of the hardness of the base metal, and the hardness of the weld bead (for example, the resolidification region) is the mother. The hardness of the material is made to be within 5%, and the hardness of the weld bead is made to be within 10% of the hardness of the base material. These methods and welds include welding two or more copper-based materials together, and in the area surrounding the weld, approved and established hardness tests (such as Vickers hardness, ASTM test, etc.) The hardness of the material (measured in) is that the HAZ hardness is within the hardness of the base material, the HAZ hardness is within 1% of the hardness of the base material, the HAZ hardness is within 5% of the hardness of the base material, and the HAZ hardness is the hardness of the base material. It should be within 10% of. These methods and welds include welding two or more copper-based materials together, and in the area surrounding the weld, the base metal, beads (eg, resolidification area), and HAZ micronities. The structure is identical and there is no discernible difference in microstructure that suggests or indicates the weakness of the weld structure in the weld area or the weakness of the weld area.

FIG. 8 is the microstructure observed for a sample of copper sheet with a thickness of 500 μm when working in keyhole welding mode. During the keyhole weld process, the steam plume was clearly visible and the molten copper was slowly extruded along the length of the weld. There were no signs of spatter during welding, usually observed when welding with an IR laser, during or after this weld. It demonstrates a stable and well-controlled keyhole process suitable for making high quality welds on electrical components. A very high quality and uniform keyhole mode weld cross section of the type shown in FIG. 8 is obtained with a low power density of 800 kW / cm ² or less. The recoagulation region [1]-[2] was 442 μm to 301 μm, and the HAZ [2] was 1314 μm.

Embodiments of the present invention provide a visible laser system to achieve efficient heat transfer rates to copper materials, stable molten pools, in particular these advantages in either the conduction mode or the keyhole mode of welding. Regarding methods, devices, and systems for using to weld copper to copper or other materials. Copper is highly absorbent in the blue wavelength range, as shown in FIG. The preferred blue laser beam and laser beam system and method according to the present invention combine laser power with copper very efficiently. The laser beam system and method heat the matrix (material to be welded, eg copper) faster than heat is conducted away from the laser spot. This provides very efficient and excellent welding properties for conduction mode laser welding. That is, the material in the laser beam is rapidly heated to the melting point and maintained at the melting point by the continuous laser beam to form a stable weld bead. In this conduction mode weld, the metal melts rapidly, but the penetration depth of the weld is determined by thermal diffusion into the material and advances into the material in a spherical shape. FIG. 10 shows a schematic view of an embodiment of the conductive mode welding 1000, and the direction of welding is indicated by an arrow 1004. For example, a blue wavelength laser beam 1001 is focused and maintained in the molten pool 1002. Behind the molten pool 1002 is the solid welding material 1003. Base materials such as copper metal and copper alloys are below the weld. Shielded gas stream 1005 is also used.

One embodiment of the present invention relates to copper keyhole welding using a blue laser system. These methods and systems open up new possibilities for welding thick copper materials and laminates, including thick laminates of copper foil. This keyhole mode weld occurs when the laser energy is rapidly absorbed and the material to be welded melts and vaporizes. The vaporized metal creates a high pressure in the metal to be welded, opening holes or capillaries through which the laser beam propagates and is absorbed. When the keyhole mode is started, deep penetration welding is performed. The absorption of the laser beam changes from 65% initial absorption of the copper blue laser to 100% absorption at the keyhole. This high absorption can be due to multiple reflections on the wall of the keyhole, where the laser beam is continuously absorbed. Combined with the high absorbency of copper at blue wavelengths, the power required to initiate and maintain a keyhole is significantly lower than when using an IR laser. FIG. 11 shows a schematic view of an embodiment of the keyhole mode welded portion 2000, and the direction of welding is indicated by an arrow 2007. Keyhole 2006 has a metal / vapor plasma. The blue laser beam 2001 forms the plasma cloud 2002, the molten pool 2003, and the solid weld metal 2004. Shielded gas stream 2005 is also used.

Comparing the keyhole weld of FIG. 11 with the conduction mode weld of FIG. 10, the wall of the final weld resolidification region of the keyhole weld is more vertical through the component or base metal than the conduction mode weld.

Preferably, the high power laser beam for embodiments of the system and method (eg, visible laser beam, green laser beam, and blue laser beam) is focused through an optical system within the system to a spot size of about 50 μm or greater. It has the performance of 10W or more. The power of the laser beam including the blue laser beam can be 10W, 20W, 50W, 100W, 10-50W, 100-250W, 200-500W, and 1,000W, and higher power and lower power are also assumed. And all wavelengths within these ranges are assumed. Spot sizes for these powers and laser beams (longest cross-sectional distance, diameter in the case of a circle) range from about 20 μm to about 4 mm, less than about 3 mm, less than about 2 mm, about 20 μm-about 1 mm, about 30 μm-about 50 μm, about 50 μm. -About 250 μm, about 50 μm-about 500 μm, about 100 μm-about 4000 μm, more and less, and all sizes within these ranges. The power density of the laser beam spot is about 50 kW / cm 2-5 MW / cm ² , about 100 kW / cm 2-4.5 MW / cm ² , about 100 kW / cm ^{2-1000 kW} / cm ² , about 500 kW / cm ^{2 -2} MW. / Cm ² , about 50 kW / cm over ² , about 100 kW / cm over ² , about 500 kW / cm over ² , about 1000 kW / cm over ² , about 2000 kW / cm over ² , and higher and lower power densities, And all power densities within these ranges. Welding speeds of copper range from about 0.1 mm / sec to about 10 mm / sec and can be slower or faster speeds, and all speeds within these ranges, depending on various conditions. Since the speed depends on the thickness of the material to be welded, the speed mm / sec / mm per unit thickness (mm) is, for example, 0.1 / sec for copper with a thickness of 10 μm to 1 mm. Can be from 1000 / sec.

Embodiments of the methods and systems of the invention can use one, two, three, or more laser beams to form welds. The laser beam can be focused on the same area to initiate welding. Laser beam spots can overlap or coincide. Multiple laser beams can be used in unison at the same time. Welding can be started using a single laser beam and then a second laser beam can be added. Welding can be initiated using multiple laser beams and then continued using fewer beams, such as a single beam. The plurality of laser beams can be of different powers or the same power, the power densities can be different or the same, the wavelengths can be different or the same, and can be combinations and variants thereof. The use of additional laser beams can be simultaneous or sequential. Combinations and variants of these embodiments using multiple laser beams can also be used. When a plurality of laser beams are used, spatter from the weld can be suppressed, and the deep penetration welding method can also suppress the spatter.

In embodiments, hydrogen gas H ₂ can be mixed with an inert gas to remove the oxide layer from the base metal during the welding process. The hydrogen gas is flowed into the welded area. Hydrogen gas also promotes wetting of welds. Hydrogen gas can be added to the shield gas or mixed with the shield gas and applied to the weld as part of the shield gas. These mixed gases include, for example, Ar-H ₂ , He-H ₂ , and _N2 -H ₂ .

FIG. 18 shows examples of penetration depth into copper, laser beam power, and welding speed for various embodiments of laser system configurations and material thicknesses ranging from 127 μm to 500 μm.

Method of conducting mode welding of copper, copper alloys, and other metals using a blue laser system

The system overcomes the problems and difficulties associated with IR welding when applied to copper-based materials. The high absorptivity (65%) of copper in the laser beam and beam spot at the blue wavelength according to the present invention overcomes the thermal diffusivity of the material and can be achieved at relatively low power levels of about 150 watts or less. The interaction of this blue laser beam with copper allows copper to easily reach its melting point, allowing for a wider process window.

In one embodiment, by using a component holding device or fixture, steady conduction mode welding is performed and high quality welding is obtained at a stable and rapid rate.

Weld fixtures are used to hold the material to be welded in place during the thermal transients induced in the part by the laser beam. The fixtures of FIGS. 12 and 12A are perspective views and cross-sectional views of weld clamps that can be used for lap welding, butt welding, and even edge welding, respectively. The weld fixative 4000 has a base plate or support structure 4002. Attached to the base plate 4002 are two clamp members or holddowns 4001. The holddown 4001 has a tab that rests on the surface of the base plate 4002 and a free end that contacts and holds the workpiece to be welded. The base plate 4002 in the region between the free ends of the holddown 4001 has, for example, a slot 4003 having a width of 2 mm and a depth of 2 mm. The four bolts 4004 (other types of adjustment tightening devices can also be used) adjust, tighten and hold the clamp to the workpiece to hold or secure the workpiece.

The fixture material is a low thermal conductivity material such as stainless steel, which is preferred because it is rigid enough to apply the clamping pressure required to hold the part in place during welding. In embodiments, the clamp, base plate, or both can provide insulating or insulating effect to the workpiece during the welding process. The use of low thermal conductivity materials in the fixture prevents, minimizes, and reduces the rapid conduction of heat stored in the component by the fixture itself. This provides additional advantages when welding high thermal conductivity materials such as copper. Therefore, the material selected for the clamp, the width of the clamp, and the gap under the part are all parameters that determine the penetration depth of the weld, the width of the weld bead, and the overall quality of the weld bead. Referring to FIG. 14, a cross section (after etching) is shown in which the conduction mode weld is identified by the circular shape 6001 of the base metal, eg, the weld bead in the workpiece. The weld has this shape due to the isotropic process of heat transfer of copper or other material when heat is applied to the top surface of the part.

In a preferred embodiment, the base plate 4002 of the fixture 4000 is made of stainless steel and is cut so that a 2 mm wide gap 4003 is located beneath the weld region to minimize oxidation of the back surface of the weld. Is infused with an inert gas such as argon, helium, or nitrogen (as a cover gas or shield gas). The cover gas can be a mixture of hydrogen and an inert gas. The clamp 4001 is designed to press the part to be welded at 2 mm from the edge of the gap 4003 of the base plate 4002. Therefore, in this embodiment, a 6 mm wide region of the part to be welded is open to the laser beam (the laser beam is slightly separated from the clamp). This arrangement of clamps not only allows the laser beam to easily access the surface, but also allows the part to be clamped firmly. This type of clamp is preferred for butt welding two copper foils or sheets with a thickness of 50 μm to several mm. This fixative is also suitable for laminating and welding two thicker copper plates in the range of 200 μm to a few mm. The magnitude of the clamping pressure is very important, depending on the magnitude of the laser power, the speed of the weld, the thickness of the part, and the type of weld performed, the clamp bolt is 0.05 Newton m (Nm), It can be tightened with a torque of up to 3 Nm, or more for thicker materials. This torque value is largely related to the size of the bolt, the meshing of the threads, and the distance from the center of the bolt to the clamp point.

In one embodiment, high quality and excellent welds are obtained by providing sufficient clamping force to prevent the movement of parts during welding while minimizing parasitic heat loss to the fixture itself. The fixture embodiments of FIGS. 12 and 12A represent a cross section of a weld fixator and represent any 2D path (eg, -S-, -C-, -W-" for welding any type of shape. Etc.) can be designed. In another embodiment, the fixture can be preheated or heated during the welding process to increase the rate or depth of weld penetration while reducing parasitic heat loss to the fixture. .. Heating the fixative to a few hundred degrees Celsius can more than double the welding speed, or penetration depth and quality. As shown in FIG. 10, the shield gas on the upper surface of the weld is supplied in the vertical direction from the front in the welding progress direction to the back in the weld progress direction. A bead-on-plate conduction mode weld performed using this fixture 4000 on a 254 μm thick copper sheet is shown in FIG. The solidification pattern of the weld bead shows a spherical melt pattern typical of this type of weld.

Overlapping welding of two parts using the conduction mode welding process requires the parts to be placed and held in close contact. The two parts (collectively workpieces) can preferably be placed in the type of fixative shown in FIGS. 13 and 13A (perspective, cross-sectional view). Fixture 5000 has a base plate 5003 and two clamps 5002. The clamp has four slots 5010 corresponding to the holddown bolt 5001. Therefore, the relative position of the clamp with respect to the workpiece and the magnitude of the clamping force or pressure can be adjusted and fixed. Fixtures can be fitted with magnets to assist in positioning and fixation. The clamp 5002 has an internal channel 5004 for feeding the shield gas. Channel 5004 communicates fluid with the shield gas outlet 5005. The shield gas outlet and shield gas channel from the shield gas supply system are in the clamp. Thus, the gas supply system is a row of holes along the length of the clamp that supplies an inert gas such as argon, helium, or nitrogen. Argon is a preferred gas because it is heavier than air and replaces oxygen and stays in the component, preventing oxidation of the top surface of the component. A small amount of hydrogen can be added to the inert gas to facilitate the removal of the oxide layer on the component and promote the wetting of the component during the melting process.

There is also an insert 5006, which is used to force individual foils within the laminate to keep and maintain contact with each other within the laminate. The insert 5006 can stretch the foil and bring it into firm and uniform contact with each other. In the embodiment of FIGS. 13 and 13A, the insert 5006 is inverted V-shaped. It can be curved, humped, or other shaped, depending on the laminate of foils, and their individual thickness. Further, in the embodiments of FIGS. 13 and 13A, the insert 5006 is adjacent to the clamp 5002 but not covered by the clamp 5002. The insert can be removed from the end of the clamp. Alternatively, one or both of the clamps may partially cover the insert.

In a preferred embodiment, the base plate 5000, like the clamp 5002, is made of stainless steel. Fixtures can be made of ceramic or insulating material. The hump 5006 applies pressure from beneath the weld to bring the overlapping plates (2, 3, 10, etc.) into close contact. In this embodiment, the means for the shield gas is incorporated into the clamp (2) in the form of a row of holes along the length of the clamp to supply an inert gas such as argon, helium, or nitrogen. It has become. Argon is heavier than air and is a preferred gas to replace oxygen and stay in the component to prevent oxidation of the top surface of the component. The insert hump 5006 of the base plate 5003 may also have a set of channels, holes or slots for supplying a cover or shield gas to the back of the weld to prevent oxidation. As shown in the figure, the fixative 5000 represents a cross section of the weld and can be designed in any 2D path for welding any shape together. In this application, the torque value of the bolt may be important depending on the nature of the workpiece, and if the torque value is too low, such as 0.1 Nm, the parts will not stay in contact and the torque value will be over 1 Nm. If too high, parasitic heat transfer reduces the efficiency of the weld process and reduces penetration and weld bead width.

How to weld copper, copper alloys and other metals in keyhole mode using a blue laser system

Blue laser light has a much higher level of absorption (65%) than IR lasers (as opposed to the 2,000-3,000 watts required for IR systems to initiate the keyhole welding process). In) keyhole welding can be started at a relatively low power level of 275 watts. At the start, the IR system further faces the problem of runaway, among other problems. When the keyhole mode is initiated on the blue laser system, absorption increases, but does not result in a runaway as it increases from 65% to about 90% and then to 100%. Thus, current keyhole welding processes have an absorption time profile that is significantly different from IR. The blue laser keyhole welding process according to the present invention has an absorption time profile of 35% or less from the start to the progress of welding. The initiation of the blue laser welding process using the laser welding system according to the present invention and the transition to continuous welding are the rapid laser power levels and welding speeds required to prevent spatter when using IR lasers. It is done without any changes. A high-speed video of the initiation of keyhole welding with a blue laser shows a stable process in which multiple layers of copper foil and plate can be welded with minimal spatter emissions from the keyhole. Cross sections of the two keyhole welded samples are shown in FIGS. 16 and 17. The material solidification pattern here is clearly different from the shape of the conduction mode welded sample shown in FIG. As can be seen in FIGS. 16 and 17, the formation of a material solidification pattern perpendicular to the surface of the material is different from conduction mode welding, which is the key for heat transfer to extend through the surface of the part to the final weld depth. This is because it occurs along the entire length of the hole. This is in contrast to conduction mode welding, where all laser energy is stored on the surface of the material.

The keyhole welding process, like the conduction mode welding process, requires that the part be held in a fixture to prevent any movement during welding. The keyhole mode is typically used in a lap weld configuration in which a keyhole penetrates a part and welds a laminate of two or more parts together (see, eg, FIG. 17).

The laser system of FIG. 20 can generate a 275 W blue laser beam with a power density of 800 kW / cm ² at the spot. The laser system of FIG. 20 has a first laser module 1201 and a second laser module 1202, and the laser beam exits the laser module and follows the laser beam path as indicated by the ray trajectory 1200. The laser beam travels through the turning mirrors 1203, 1204, and the condensing lens section 1205 with a 100 mm condensing lens and a 100 mm protective window. The focusing lens of the focusing lens unit 1205 forms a spot 1250.

The laser system shown in FIG. 21 can be used to form a 400 μm spot or a 200 μm spot. The laser system of FIG. 21 is composed of four laser modules 1301, 1302, 1303 and 1304. Each laser module can be of the type disclosed and taught in US Patent Publication No. 2016/0322777, the entire disclosure of which is incorporated herein by reference. For example, the module can be of the type shown in FIG. 19, and the composite beam from each laser diode subassembly 210, 210a, 201b, 210c propagates to a patterned mirror, eg 225, to this. The mirror directs and couples the beams from the four laser diode subassemblies into a single beam. The polarized beam folding assembly 227 folds the beam in half on the slow axis, doubling the brightness of the composite laser diode beam. Telescope assembly 228 expands the combined laser beam in the slow axis or compresses the fast axis, allowing the use of smaller lenses. The telescope assembly 228 shown in this example magnifies the beam 2.6 times and increases its size from 11 mm to 28.6 mm, while reducing the divergence of the slow axis by the same 2.6 times. When the telescope assembly compresses the speed axis, the speed axis is reduced from a height of 22 mm (entire composite beam) to a height of 11 mm to make a double telescope with an 11 mm x 11 mm composite beam. This is a preferred embodiment because of its low cost. The aspherical lens 229 focuses the composite beam.

It should be appreciated that at a spot of 500 watts and 200 μm, the power density is greater than 1.6 MW / cm ² which is substantially above the keyhole weld threshold at this wavelength. At this power density, even a blue laser can create spatter and porosity in the weld. However, because absorption is well controlled, spatter can be suppressed, controlled, or eliminated. The first method for suppressing spatter is to reduce the power level when spatter is started while keeping the welding speed constant. The second method of suppressing spatter is to lengthen the molten pool and discharge the shield gas and vaporized metal from the keyhole to perform welding without spatter or defects. A third method for suppressing spatter is to rock the blue laser beam using either a set of mirrors attached to a set of galvanometer motors or a robot. A fourth method of suppressing spatter is to reduce the pressure in the weld environment, including the use of vacuum. Finally, a fifth method for suppressing spatter is to modulate the laser beam power in the range of 1 Hz to 1 kHz, or up to 50 kHz. Preferably, the weld parameters are optimized to minimize spatter during the process.

Embodiments of the present invention generally include laser processing of a material, laser processing by matching a preselected laser beam wavelength to a material that is processed to have high or increased levels of absorption by the material, in particular. The present invention relates to laser welding of a material using a laser beam that is highly absorbent by the material.

One embodiment of the invention uses a laser beam having visible laser beams with wavelengths from 350 nm to 700 nm to weld or laser-bond materials with higher absorption to these wavelengths. Regarding. In particular, the laser beam wavelengths are at least about 30%, at least about 40%, at least about 50%, and at least about 60%, or more, and about 30% to about 65%, about 35% to 85%, about 80. %, About 65%, about 50%, and about 40% are pre-determined based on the material to be laser processed to have absorbency. Thus, for example, a laser having a wavelength of about 400 nm to about 500 nm for welding gold, copper, brass, silver, aluminum, nickel, alloys of these metals, stainless steel, and other metals, materials, and alloys. Beam is used.

Blue lasers for welding gold, copper, brass, silver, aluminum, nickel, nickel-plated copper, stainless steel, and other materials, plated materials, and alloys, such as wavelengths from about 405 nm to about 495 nm. It is preferred because of the high absorbency of the material at room temperature, eg, more than about 50% absorbency. One of the advantages of the present invention is the ability of a preselected wavelength laser beam, such as a blue laser beam, which better couples the laser energy into the material during laser manipulation, eg, welding process. be able to. By better coupling the laser energy to the material to be welded, the possibility of runaway in the weld is greatly reduced and preferably eliminated. Better coupling of laser energy also allows the use of lower power lasers, saving costs. Better coupling also provides better control, higher tolerances and therefore better reproducibility of welds. These features not found in IR lasers and IR laser welding operations are especially important for products in the fields of electronics and power storage.

In one embodiment, a blue laser operating in CW mode is used. CW operation is used in many applications because it quickly and completely modulates the laser power, can control the welding process with a feedback loop, and enables a reproducible process with optimal mechanical and electrical properties. Prefered over pulsed lasers.

One embodiment of the invention includes laser treatment of one, two or more components. The component is formed from any type of material that absorbs the laser beam, laser beam energy, such as plastics, metals, composites, amorphous materials, and other types of materials. In one embodiment, laser machining involves soldering two metal parts together. In one embodiment, laser machining involves welding two metal essentials together.

In one embodiment, tools, systems, and methods are provided in which the laser welding operation is selected from the group consisting of self-welding, laser hybrid welding, keyhole welding, lap welding, fillet welding, butt welding, and non-self-welding. Weld.

Laser welding techniques can be useful in many different situations, especially when welding is required to form an electrical connection, especially in a power storage device such as a battery. In embodiments of the laser welding operation and system of the present invention, only the base metal is used and can be self-welded such as keyhole welding, conduction welding, lap welding, fillet welding and butt welding, generally visible wavelength, preferably blue. Includes laser of wavelength. Laser welding can be non-native, and filler material can be added to the melt pool to "fill" the gap or create a raised bead for the strength of the weld. Laser welding techniques also include laser material deposition (“LMD”).

Embodiments of the present laser welding operation and system include lasers of visible wavelength, preferably blue wavelength, which can be hybrid welding in which an electric current is used in combination with a laser beam to provide a faster supply of filler material. Laser hybrid welding is, by definition, non-natural.

Preferably, in some embodiments, an active weld monitor, eg, a camera, can be used to check the quality of the weld on the fly. These monitors can include, for example, X-ray and ultrasonography systems. In addition, on-stream beam analysis and power monitoring can be used to fully understand the characteristics and operational characteristics of the system.

Embodiments of the laser system of the present invention can combine novel laser systems and methods with conventional milling machines and machining equipment to form hybrid systems. In this way, materials can be added and removed during manufacturing, construction, refinishing, or other processes. Examples of such hybrid systems using other embodiments of the laser system invented by one or more of the present inventors are disclosed and taught in US Patent Application No. 14 / 837,782. The entire disclosure is incorporated herein by reference.

Typically, in embodiments, laser welding involves a very low gas flow to keep the optics clean, an air knife to keep the optics clean, or an inert environment to keep the optics clean. To use. Laser welding can be performed in air, an inert environment, or other controlled environment, such as _N2 .

Embodiments of the invention have copper, pure copper, an alloy of copper, and a sufficient amount of copper to have about 40% to 75% absorbency at a blue laser wavelength, preferably from about 400 nm to about 500 nm. Great advantages can be found in welding copper materials, including all materials.

There are two preferred modes of self-welding performed in the present laser system and process embodiments, conduction welding, and keyhole welding, and the self-welding portions they produce. Conduction welding is the case of welding two metal pieces using a low-strength (<100 kW / cm ₂ ) laser beam. Here, two pieces of metal can be butted against each other, stacked on one side, and completely stacked. Conduction welds tend not to penetrate as deeply as keyhole welds and generally produce characteristic "spherical" weld joints for very strong butt welds. However, keyhole welds occur at relatively high laser beam intensities (> 500 kW / cm ₂ ), and this weld can penetrate deep into the material, often with multiple layers when the materials overlap. Can penetrate. The exact threshold for the transition from conduction mode to keyhole mode has not yet been determined with a blue laser source, but keyhole welding has a characteristic "v" shape at the top of the material, deep into the material. There are nearly parallel channels of fused recondensed material. The keyhole process transfers laser energy deep into the material by reflecting the laser beam from the sides of the metal reservoir. Although these types of welds can be performed with any laser, blue lasers are expected to have significantly lower thresholds for initiating both of these types of welds than infrared lasers.

Welding of electroplated materials that use blue laser operation to weld these materials includes materials electroplated with copper, materials electroplated with platinum, and materials electroplated with other conductive materials. It is possible to include blue laser welding of the electroplating material of.

The copper welding process requires that power be efficiently coupled to the part, the welding process is stable, low porosity and low spatter welding can be produced. The present invention achieves these and other objects. The blue laser achieves the first requirement of these requirements by having a wavelength that is highly absorbed by copper (65%) compared to the IR laser (<5%). The second requirement is not only laser absorption, but also a function of the processing ramp or time profile, fixture, beam profile and quality, and the clamping pressure used for the part. This embodiment uses a blue laser as a heat source to enable welding in both keyhole mode and conduction mode. Conduction mode welding does not cause spatter or make parts porous during the process. Welding keyhole mode allows for greater penetration. Embodiments of the high power blue CW laser light source of the present invention are ideal for porosification of very low parts and welding of copper parts with very little spatter during the process.

A bead-on-plate test in which a 1 mm thick copper plate was completely melted using a 600 watt blue laser with a slight amount of spatter left on the surface. A 600 watt CW laser is focused to a spot size of about 200 μm, resulting in an average intensity of 2.1 MW / cm ² on the surface of the component. This strength far exceeds the power density required to initiate and maintain the keyholes in the component. During the welding process, keyholes are rapidly formed and complete penetration is achieved, the melt pool shows a very stable surface and there is less turbulence in the molten pool as the weld progresses. A stable welding process is observed at a wide range of welding rates, among other things, using Ar-CO ₂ cover gas, to suppress surface oxidation during the welding process. This ability to form stable keyhole welds can be attributed, among other things, to the high absorbency of blue copper. The blue laser light is uniformly absorbed by the wall of the keyhole during the welding process, but when the turbulence in the melt pool makes the inside of the keyhole unstable, heat input is maintained and the keyhole is stable. It becomes a state.

The following examples are provided to illustrate the present laser system and various embodiments of operation, in particular a blue laser system for welding components including components within an electronic storage device. These examples are for illustration purposes only, may be predictive, and should not be considered to limit the scope of the invention.

Example 1

The laser light source is a high power blue direct diode laser capable of 0-275 watts. The beam is supplied via a 1.25x beam expander and focused by a 100 mm aspheric lens. The spot diameter of the workpiece is 200 μm × 150 μm and produces a power density of maximum power of 1.2 MW / cm ² . The sample was held in place using a stainless steel fixture and tested using He, Ar, Ar-CO ₂ , and nitrogen. All of these were beneficial and the best results were obtained with Ar-CO ₂ .

Example 1A

Initial test results using the system of Example 1 formed high quality conduction mode welds on a copper surface at a power level of 150 watts. A series of bead-on-plate (BOP) tests were performed to evaluate the characteristics of the welds produced by the high power blue laser light source. FIG. 1 shows a chevron pattern of a conduction mode weld. The unique characteristics of this weld are that there is no spatter in the welding process, it has a microstructure similar to the base metal, and the hardness of the weld is similar to the base metal. FIG. 1 shows a BOP formed when welding on a 70 μm thick copper foil at 150 watts using a blue laser.

Example 1B

Using the system of Example 1 and scaling the laser power to 275 watts, the power density increased to 1.2 MW cm ² , which is sufficient power density for the first keyhole weld of copper. FIG. 2 shows an example of a keyhole welded portion of a copper sample having a thickness of 500 μm. During the keyhole process, the vapor pressure generated in the keyhole pushes the molten copper out of the weld bead. This can be seen in FIG. 2, where the extruded copper linearly produces the edges of the weld bead. This extrusion process is stable and does not cause micro-explosions in the material and therefore does not produce the spatter pattern observed when welding copper with an IR laser source.

Example 1C
Welding experiments were performed using the system of Example 1 for copper thicknesses in the range 127-500 μm. FIG. 3-FIG. 5 summarizes the results of these BOP tests. FIG. 3 shows a complete penetration up to 9 m / min at 275 W, followed by a decrease in penetration depth at the expected rate. FIG. 4 shows the BOP results at a maximum of 0.6 m / min without an assist gas and at a maximum of 0.4 m / min when an Ar-CO2 cover gas is used. FIG. 5 shows the relationship between the penetration depth and the velocity of 500 μm copper at 275 W.

Example 2

Fixture 5000 of FIGS. 13 and 13A is used for proper lap welding of two copper foil laminates with a thickness of 178 μm in conduction mode welding. When the fixative is heated to a few hundred degrees Celsius, the energy lost due to heating the part during welding is provided by this heating, thus more than doubling the welding speed and quality. As shown in FIG. 10, the shield gas on the upper surface of the weld is sent from the front in the welding progress direction to the back in the weld progress direction.

Example 3

Two 125 μm thick copper plates were stacked together using Fixture 5000 and welded by conduction mode welding. This weld is shown in the cross-sectional photograph of FIG.

Example 4

In FIGS. 13 and 13A, a stack of 40 copper foils with a thickness of 10 μm is welded using a fixative 5000 with no porosity and no defects. A cross section of this weld is shown in FIG. Welding of this laminate depends on the method of preparing the foil, the method of clamping the foil, and the torque applied to the clamp. The foil is sheared and flattened, then washed with alcohol to remove production or handling oil, and finally stacked in the fixture. The clamp bolt 5001 is torqued to 1 Nm to ensure that the part is firmly held in place during the welding process. The lasers used to weld these parts are four 150 watt lasers shown in FIG. 19 optically combined as shown in FIG. 21 to form a 500 watt laser system. The laser produces 400 μm spots with an average power density of 400 kW / cm ² and a peak power density sufficient to initiate the keyhole welding process.

Example 5

Embodiments of this laser beam welding technique are evaluated using first fully melted bead-on-plate (BOP) welding of a 1 mm thick copper plate using a 600 watt blue laser with slight spatter remaining on the surface. Will be done. The 600 watt CW laser is focused to a spot size of about 200 μm, resulting in an average intensity of 2.1 MW / cm ² on the surface of the component. This strength is well above the power density required to initiate and maintain the keyholes in the component. During the welding process, keyholes are observed to form rapidly, and when complete penetration is achieved, the melt pool shows a very stable surface and less turbulence in the molten pool as the weld progresses. Show that. A stable welding process was observed at a wide range of welding speeds using AJ-CO2 cover gas to suppress surface oxidation during the welding process. This ability to produce stable keyhole welds may be due to the high absorptance of copper in blue and the uniformity and high quality of the laser beam. The blue laser light is uniformly absorbed by the wall of the keyhole during the welding process, but when the keyhole becomes unstable due to the turbulence of the melt pool, heat input is maintained and the keyhole remains stable. ..

Example 6

Embodiments of the invention use the high power visible lasers of the invention, particularly blue lasers, turquoise lasers and green lasers, in industrial applications such as welding. In embodiments of these processes, power levels of 500-600 watts and spot sizes of 200-400 μm are used. The wavelengths of these embodiments are in the blue range. Stable conduction mode welding of copper is observed over a wide range of speeds at both 400 μm and 200 μm spot sizes for oxygen-free copper (OFC). This welding mode is spatter-free, dense enough, and none of the welded parts show porosity. Stable keyhole mode welding is observed in copper with a spot size of only 200 μm, but with low conductivity materials such as Inconel and stainless steel, keyhole welding can be obtained even with a spot size of 400 μm. Modeling of the welding process reveals that there is a significant difference in the shape and size of the molten pool when welding copper compared to stainless steel. Stainless steel with low thermal conductivity shows the well-known teardrop-shaped molten pool, while copper with high thermal conductivity has the same power level as used for welding stainless samples and is much larger in size. Shows a small circular molten pool.

Example 7

Laser welding of metals using a blue, turquoise, or green laser beam is done without wobbling the beam. These welds are deeply fused. Therefore, these laser beams are used to provide unwabbing-free welding of metals, including copper foil, and copper plates. No wobbling welding is provided for aluminum, stainless steel, copper, aluminum-based metals, stainless steel-based metals, copper-based metals, and alloys thereof.

In this embodiment of laser welding without wobbling, blue laser welding is performed using a blue laser beam having a wavelength of 450 nm with respect to copper having a thickness of less than 1 mm.

In this embodiment of laser welding without wobbling, blue laser welding is performed using a blue laser beam having a wavelength of 450 nm with respect to aluminum having a thickness of less than 1 mm.

In this embodiment of laser welding without wobbling, blue laser welding is performed using a blue laser beam having a wavelength of 450 nm on stainless steel having a thickness of less than 1 mm.

Example 8

In one embodiment, a 600 watt laser with four 200 watt blue laser modules providing a laser beam with a wavelength of 450 nm is used. The laser diodes are individually collimated, the beam divergence is circularized as shown in FIG. 19, and the beam parameter product of each module is 22 mm mad. The laser beams from the four blue laser modules are optically sheared both horizontally and vertically to fill the aperture of the focused optics with a diameter of 100 mm, as shown in FIG. This composite beam (450 nm) has a beam parameter product of 44 mm mad and is suitable for firing into 400 μm fibers. For Examples 8A to 8K and 9, no optical fiber is used and the blue laser beam is sent to the workpiece through free space.

In these examples, an optical breadboard with a 4'x 6'optical bench that allows real-time beam diagnostics to be integrated into the setup is used. The combined power beam is sampled with a 1% beam sampler and part of the beam is sent to a far-field profile camera and power meter. The far field of view is generated by either a 100 mmF / 1 lens or a 200 mmF / 2 lens, which is a lens with the same focal length as the welded lens. Both lenses are Thorlabs BK7 aspherical lenses. The lens is underfilled to about 80 mm, and the spot on the workpiece is about 200 μm for a 100 mm FL lens and about 400 μm for a 200 mm FL lens.

Beam caustics are measured by translating the Ophir beam profiler through the focal point of a 100 mm FL lens within the beam sampling arm of the setup and measuring the beam diameter at a 95% enclosed PowerPoint. A graph of beam caustics is shown in FIG. This measurement shows that the depth of focus of the 100 mm FL lens is relatively short.

Using a FANUC 6-axis robot (FANUC M-16iB), the cover gas is provided by a 3/8 inch diameter sparger tube attached to the robot adapter and oriented along the direction of the weld. , The sample is moved through the free space beam focal point. In Examples 8A-8K and 9, the type of weld fixative shown in FIGS. 12 and 12A is used. Weld fixtures are part of the welding process and can affect the resulting penetration depth, welding speed, or both when welding high thermal conductivity materials. 12 and 12A are drawings of embodiments of the weld fixative. In one embodiment, aluminum (6061 series) is used. In another embodiment, stainless steel (316) is used. Welded fixtures of aluminum tend to draw heat from the part rapidly, while stainless steel fixtures can retain most of the heat inside the part. Both materials are evaluated along with various methods for clamping samples (workpieces, parts, etc.). An inert gas such as argon-CO ₂ is flowed over the part placed on the fixative to suppress oxidation of the part during the welding process. A small gap 4003 is placed below the center of the sample to minimize heat dissipation at the point of the bead-on plate and allow additional assist gas to be added to the back of the weld.

Welding keyhole mode can produce a strong plume during welding. Atoms and ions in the plume easily absorb 450 μm of light, so this plume needs to be controlled and preferably suppressed. A tube sparger with a diameter of 3/8 inch is used to suppress the plume by supplying 50 scfh of argon or argon-CO2 to the top of the part. Welding can be performed or formed with various gases such as argon, argon-CO2, air, helium, nitrogen to control the plume and avoid oxidation of the part. The purpose of optimizing the welding process is, among other things, to achieve maximum penetration at the highest possible speeds. The data presented in Examples 8A-8K use argon as the cover gas. For other laser welding and laser machining applications such as butt welding, plume management is desirable and preferred.

In the 500 watt welding test of Examples 8A to 8F, a lens with a focal length of 200 mm was used to focus the beam to a spot size of 400 μm, with an average intensity of over 400 kW / cm ² and a peak intensity of 800 kW / cm. Get closer to ² .

In the 600 watt welding test of Examples 8G to 8K, a 100 mm focal length lens was used to focus the beam to a spot size of 200 μm, an average intensity of about 2.1 MW / cm ² , and a peak intensity of 4. Bring it closer to 5 MW / cm ² .

Example 8A

Using the laser, process, and setup of Example 8, 500 watts, 400 μm spot size, and 400 kW / cm ² for copper (OFC), stainless steel (304), and aluminum (1100 series). Perform and evaluate bead-on-plate welds using average power density. All samples are sheared to a size of 10 mm x 45 mm and washed with acetone prior to treatment. The surface finish is provided by McMaster-Carr and looks like a roll finish for thin samples and a mill finish for thick samples. These assessments characterize the full penetration capacity of the welding process of Example 8 for a given sheet thickness.

Using the laser, process, and setup of Example 8, bead-on-plate evaluation is performed on oxygen-free copper (99.99% -110) samples ranging in thickness from 80 μm to 500 μm. FIG. 23 shows the weld rate at which a complete penetration bead is observed behind the welded sample.

The sample was wiped with acetone prior to evaluation and the bolt was torqued at 1 Newton meter to secure it to the fixture. The fixture and sample are held at an angle of 20 degrees to the beam normal to prevent back reflections on the laser, and in the case of a 200 mm FL lens the spot extends to 400 μm × 540 μm. The beam angle is from the beam normal to the trailing side of the weld. This tilt of the sample can reduce the maximum weld speed obtained due to the low strength on the part. The welding sequence confirms that the robot has been instructed to move the part with sufficient distance between the part and the laser beam, the robot has reached the programmed speed, and the weld fixture positions the laser beam. The laser is started when crossing. The part passes through the beam at a constant speed, and when it reaches the end of the weld fixture, the laser beam is turned off and the robot is instructed to return to its home position. The sample is cross-sectioned, polished and etched to reveal its microstructure. All welds showed a spherical melt solidification pattern indicating conduction mode welds.

Example 8B
The butt welds of the samples were also evaluated using the lasers, processes, and setups of Examples 8 and 8A. The parts were prepared in the same manner as in Example 8A and clamped with the same clamping force. The edges of the sample created by shearing form the basis of the butt weld. Some of the results of these tests are shown in FIG. Welding speed is the speed at which two parts are joined with full penetration welding appearing on the back side of the welded part. No spatter was seen during or on the welded parts, indicating the welding process in conduction mode.

Example 8C

During the evaluation of the copper 110 series samples of Example 8A, a dependence on the penetration depth of the weld as a function of sample thickness was observed. FIG. 25 shows how the penetration depth decreases as the thickness of the copper sample increases. This dependence is due to the high thermal mass of the component and the high thermal conductivity of copper, which rapidly dissipates heat from the weld bead. This is partly due to the high thermal conductivity and the ability of copper to effectively dissipate laser energy during the welding process. As shown in FIG. 25, at a given rate, the penetration depth can decrease to less than a quarter as the thickness of the material doubles. In the top example, the rate is much slower and the copper's ability to dissipate laser energy is saturated, so its penetration rate does not decrease as dramatically as in the other two examples. Therefore, when designing a copper welding process using the conduction mode process, it is necessary to consider the finite thickness of the parts to be welded.

Example 8D
Samples of the Aluminum 1100 series are welded and evaluated using the lasers, processes, and setups of Examples 8 and 8A. A sample of the aluminum 1100 series was prepared and attached to the weld fixative in the same manner as the copper component of Example 8A. The welding process is similar to the copper welding process of Example 8A, but only the speed of the robot is changed. The welding speed shown in FIG. 26 is for the case where a complete penetration bead is observed on the back side of the portion of the thickness. There is no spatter from the melt pool observed during the welding process.

Example 8E

Using the lasers, processes, and setups of Examples 8 and 8A, butt welds and weld tests are performed on two aluminum 1100 samples placed side by side on a weld fixture. The sample is prepared by shearing and no special preparation is made on the two edges before the weld is performed. The sample is wiped with acetone before welding. The welding process is the same as described for the copper part of FIG. 8A, except for the welding speed. The final weld rate plotted is the rate at which a complete penetration bead is obtained over the entire length of the sample to be welded. A summary of this data is shown in FIG.

Example 8F

BOP welds and weld tests are performed on 304 stainless steel samples using the lasers, processes, and setups of Examples 8 and 8A. The sample was cut to a size of 10 mm x 45 mm that fits in the fixative, wiped with acetone, and the speed of the robot was adjusted until a full penetration weld was obtained. Again, no spatter or porosity was observed in the welded sample. The results of this test are shown in FIG.

Example 8G

Welding and evaluation of the 600 watt system and process of Example 8 is performed. A lens with a focal length of 100 mm is used to focus the beam to a spot size of 200 μm, with an average intensity of approximately 2.1 MW / cm ² and a peak intensity approaching 4.5 MW / cm ² . A series of welds are performed and tested at this higher power level using a lens with a shorter focal length (100 mm) to further evaluate the melting ability of this laser at various velocities. In these tests, the average strength was 2.1 MW / cm ² , a power density well within the requirements for vaporizing copper to create keyholes. The part is tilted 20 degrees and the effective power density is reduced to 1.4 MW / cm ² , which is strong enough to initiate the keyhole welding mode of copper, aluminum and stainless steel.

The first sign of the copper keyhole process was a significant increase in spatter during the welding process. This spatter is observed with an on-axis camera while monitoring the molten pool. Weld samples are cross-sectioned, polished, and etched to reveal microstructure freezing patterns typical of keyhole welding. The cross section also shows a significant amount of porosity whenever the beam does not completely penetrate the part. However, a slight porosity was shown in the part where the beam was completely transmitted.

Example 8H

Using the lasers, processes, and setups of Examples 8 and 8G, the weld shown in the photograph of FIG. 29, showing a longitudinal cross section of a keyhole mode weld on a copper 110 plate with a thickness of 500 μm. Determine the porosity along the entire length. The first 1 cm of the weld on the right side of the photo showed a significant amount of porosity and lack of penetration into the sample. When heat builds up on the part during welding, the keyhole process completely melts into the copper plate. This result shows that if the keyhole process can be stabilized, a weld with slight spatter and porosity can be produced.

Example 8I

Using the lasers, processes, and setups of Examples 8 and 8G, based on the results from Example 8H, welding and testing is performed that can first stabilize the keyhole before moving the part. The welding process allows the laser beam to stay in the part for a short period of time, after which the robot is accelerated and the keyhole is dragged into the part. A series of tests were conducted in which the residence time was changed from 0.6 seconds to 1.5 seconds, and favorable results were obtained with a residence time of 0.6 seconds. FIG. 30 is a photograph of a cross section of a bead-on-plate welded portion of copper 110 in which a sample was allowed to stay on the sample for 0.6 seconds and then the sample was translated at a speed of 1.1 m / min. A series of welds was performed at this speed, confirming that the process was stable and well controlled. All samples showed similar results, i.e. very low porosity, and very stable keyhole welds.

Example 8J

Welding is performed and evaluated in different thickness ranges of copper 110 material using the lasers, processes, and setups of Examples 8 and 8G. A plot of the maximum weld rate achieved for complete penetration of each sample is shown in FIG. Keyhole mode welds, translation mode welds, and conduction mode welds are all observed at these weld speeds. As a result, the welding speed and penetration depth are significantly improved compared to a system at 500 watts and 400 μm.

Example 8K

Using the lasers, processes, and setups of Examples 8 and 8G, stainless steel samples are welded and evaluated. As a result, four pieces of 304 stainless steel are laminated and welded at a speed of 1.2 m / min. The cross section shown in FIG. 32 shows a standard profile of a keyhole weld sample. The porosity at the bottom of the keyhole may be due to the gap between the third and fourth sheets of the laminate. This porosity can be eliminated by optimizing this welding process.

Example 9

Using the lasers, processes, and setups of Examples 8 and 8A, a series of tests was performed with a laminate of oxygen-free copper foils and how many foils could be laminated and welded in a single pass. Is determined. The experimental setup is the same as in Example 8, but with a modified fixture and a small steel insert in the gap below the center of the foil. The foil is fixed in place, tilted at an angle of 20 degrees with respect to the beam normal, and passed through the beam while being supplied with Ar-CO ₂ cover gas. The results of these tests on up to 40 foils in the laminate are summarized in FIG. Two different lens configurations are used and very good results are obtained over a wide range of foil thicknesses and laminates.

FIG. 34 is a photograph of an example of a successful weld of 40 copper foils with no porosity and no spatter on the top surface. The laminate of foil was welded using a 200 mm FL lens corresponding to a spot size of 500 watts and 400 μm. The welding speed was 0.5 m / min. The method of clamping the sheet can affect the weld quality, and a good and uniform clamp of the sheet provides consistently high quality welds.

Headings and Embodiments

It should be understood that the use of headings herein is for the sake of clarity and is by no means limiting. Therefore, the processes and disclosures described under the headings should be read in the context of the entire specification, including various examples. The use of headings herein should not limit the scope of protection of the invention.

It is not necessary to provide or discuss the theory underlying the novel and groundbreaking processes, materials, performances, or other beneficial features and properties that are the subject of or related to embodiments of the present invention. Please note. Nevertheless, various theories are provided in this specification to further advance the technology in this field. The theory set forth herein does not limit, limit, or narrow the scope of protection given to the inventions described in the claims, unless otherwise stated. These theories will not be needed or practiced in order to utilize the present invention. Further, it is understood that the present invention may lead to new, previously unknown theories for explaining the functional features of embodiments of the methods, articles, materials, devices, and systems of the present invention. I want to be. And the theory developed after that should not limit the scope of protection given to the present invention.

Various embodiments of the systems, devices, techniques, methods, activities and operations described herein are used in various other activities and other areas in addition to those described herein. can do. In particular, embodiments of the invention are used with the methods, devices and systems of Patent Application Publication Nos. WO2014 / 179345, US2016 / 0067780, US2016 / 0067827, US2016 / 0322777, US2017 / 0343729, US2017 / 0341180, and US2017 / 0341144. Each disclosure can be incorporated herein by reference in its entirety. Further, these embodiments are used with, for example, other equipment or activities that may be developed in the future, existing equipment or activities that may be partially modified based on the teachings of this specification. be able to. Moreover, the various embodiments described herein can be used with each other in various different combinations. Thus, for example, the configurations provided in various embodiments herein can be used with each other. For example, the components of the embodiment having A, A'and B, and the components of the embodiment having A'', C and D may be in various combinations, eg, A, C, as taught herein. D and A, A'', C, D, etc. can be used with each other. The scope of protection provided to the present invention should not be limited to the particular embodiments, configurations or arrangements shown in the particular embodiments, examples, or embodiments of the drawings.

The present invention can be embodied in forms other than those specifically disclosed herein, without departing from its spirit or essential characteristics. The embodiments described should be considered in all respects only as illustrations and should be considered non-limiting.

Claims (20)

It is a method of laser welding multiple copper foils together.
a. With the step of placing multiple copper foils containing at least about 50% copper on the welding stand;
b. With the step of applying a clamping force to the plurality of copper foils and clamping the copper foils together in the welding stand;
c. A step of directing a blue laser beam toward the copper foils along a laser beam path, wherein the laser beam;
i. At least 500 watts of power;
ii. Beam parameter product of about 44 mmrad or less;
iii. Spot size of about 400 μm or less;
iv. Average intensity of at least about 400 kW / cm ² ; and v. Peak intensity of at least about 800 kW / cm ² ;
Have,
d. The blue laser beam was adapted to lap weld the plurality of copper foils at a certain welding rate, with a step;
e. Non-oxidation that prevents oxidation of the plurality of copper foils by removing the plume material from the laser beam path in the space along the laser beam path in which the laser beam travels in free space from the optical element to the plurality of copper foils. With steps to provide sex beam clearing gas;
Have,
f. The weld rate, clamping force, and flow rate of the non-oxidizing clearing gas are configured to be pre-determined to provide lap welds without visible spatter and visible porosity. Method. The method of claim 1, wherein the beam is a CW beam. The method of claim 1, wherein the beam is a pulse beam. The method of claim 1, wherein the beam has a wavelength of about 450 nm. The method of claim 1, wherein the optical element is selected from the group consisting of a lens, a fiber surface, and a window. The method of claim 1, wherein the clearing gas is selected from the group consisting of argon, argon-CO ₂ , air, helium, and nitrogen. The method of claim 1, wherein the laser beam is not wobbled, thereby providing a laser welding process without wobbling. The method of claim 1, wherein the plurality of copper foils have 10 to 50 sheets of foil. The method of claim 1, wherein the copper foil has a thickness of about 80 μm to 500 μm. The method of claim 8, wherein each of the plurality of copper foils has a thickness of about 80 μm to 500 μm. The method of claim 1, wherein the welding speed is at least 10 m / min. It is a method of laser welding multiple metal pieces together.
a. With the step of placing multiple pieces of metal in the welding stand;
b. With the step of applying a clamping force to the plurality of metal pieces to clamp the metal pieces together in the welding stand;
c. A step of directing a blue laser beam toward the plurality of metal pieces along a laser beam path, wherein the laser beam is;
i. At least 500 watts of power;
ii. Beam parameter product of about 44 mm mad or less;
iii. Spot size of about 400 μm or less;
iv. Average intensity of at least about 400 kW / cm ² ; and v. Peak intensity of at least about 800 kW / cm ² ;
Have,
d. The blue laser beam is adapted to weld the plurality of metal pieces together at a certain welding rate, with a step;
e. In the space along the laser beam path where the blue laser beam travels in free space from the optical element to the plurality of copper foils, the plume material is removed from the laser beam path to prevent oxidation of the plurality of copper foils. With the step of providing an oxidizing beam clearing gas;
Have,
f. The welding speed, clamping force, and flow rate of the non-oxidizing clearing gas are pre-determined to provide welding without visible spatter and visible porosity. 12. The method of claim 12, wherein the welding stand has an air gap beneath the piece of metal. 12. The method of claim 12, wherein the metal is selected from the group consisting of aluminum, stainless steel, copper, aluminum-based metal, stainless steel-based metal, copper-based metal, aluminum alloys, stainless steel alloys, and copper alloys. 14. The method of claim 14, wherein the laser beam has a wavelength of about 450 nm. 15. The method of claim 15, wherein the laser beam is not wobbled, thereby providing a laser welding process without wobbling. 16. The method of claim 16, wherein the weld is selected from a group of welds consisting of lap welds, butt welds, bead-on plate welds, and conduction mode welds. 12. The method of claim 12, wherein the laser beam is not wobbled, thereby providing a laser welding process without wobbling. 12. The method of claim 12, wherein the weld is selected from a group of welds consisting of lap welds, butt welds, bead-on plate welds, and conduction mode welds. It is a method of laser welding multiple copper foils together.
a. With the step of placing a plurality of copper foils containing at least about 50% copper and having a thickness of about 80 μm to 500 μm on the welding stand;
b. With the step of applying a clamping force to the plurality of copper foils and clamping the copper foils together in the welding stand;
c. A step of directing a blue laser beam toward the copper foils along a laser beam path, wherein the laser beam;
i. At least 600 watts of power;
ii. Beam parameter product of about 44 mm mad or less;
iii. Spot size from about 200 μm to about 400 μm;
iv. Average intensity of at least about 2.1 MW / cm ² ; and v. Peak intensity at least close to about 4.5 MW / cm ² ;
Have,
d. The blue laser beam is adapted to weld the plurality of metal pieces together at a welding rate of at least 10 m / min;
e. Non-oxidation that removes plume material from the laser beam path into the space along the laser beam path where the laser beam travels in free space from the optical element to the plurality of copper foils and prevents oxidation of the plurality of copper foils. With steps to provide sex beam clearing gas;
Have,
f. The welding speed, clamping force, and flow rate of the non-oxidizing clearing gas are configured to be pre-determined to provide welding without visible spatter and visible porosity. ..

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