Laser-induced forward transfer method for forming highly-conductive metal structure

Abstract

Disclosed in the present invention is a laser-induced forward transfer method for forming a highly-conductive metal structure, comprising the following steps: A, preparing a metal transfer film and a receptor substrate; B, applying transfer laser to the metal transfer film, and depositing at the top of the receptor substrate to form an intermediate structure; and C, heating the intermediate structure to 800℃ or above, and cooling same to obtain a metal transfer structure, the metal transfer film comprising a transparent substrate and a transfer metal layer which are attached to each other, the transfer metal layer comprising copper and silver, the silver content of the transfer metal layer being 5-95%, the transfer metal layer at least comprising two transfer films, the transfer film in contact with the inner surface of the transparent substrate being a copper film or a copper alloy film, and the copper content of the copper alloy film being ≥70%. The present solution provides the transfer method which additionally provides a thermal annealing step in the transfer method and optimizes the layer structure of the transfer metal layer used for metal transfer, thus helping to obtain metal transfer structures having low porosity and low resistivity.

Description

A laser-induced forward transfer method for forming highly conductive metal structures

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application number 202311605253.7, filed with the Chinese Patent Office on November 27, 2023, entitled "A Laser-Induced Forward Transfer Method for Forming Highly Conductive Metal Structures," the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present invention relates to the technical field of laser induced transfer, and in particular to a laser induced forward transfer method for forming a highly conductive metal structure. Background Art

[0004] Laser-induced transfer technology refers to the use of pulsed laser irradiation on a material film attached to a transparent substrate. The laser energy is absorbed by the film and converted into heat, causing the film under the laser action area to melt, vaporize, etc., and then detach from the substrate under the combined action of vaporization pressure, surface tension, etc. to form jet droplets, which are finally deposited on the receptor substrate to form a two-dimensional or three-dimensional transfer structure. Laser precision processing technology, this technology is mainly used in the transfer process of metals, slurries, polymers and cell tissues.

[0005] In some applications, laser-induced forward transfer (LIFT) technology aims to produce metal transfer structures with low resistance. For example, some special devices require low-resistance metal transfer structures close to copper to ensure signal loss. However, due to limitations in existing technology, metal transfer structures prepared using LIFT technology generally have high resistance. The reason is that LIFT technology requires the use of metal films with nanometer or submicron thickness, and the volume of the sprayed droplets formed after laser irradiation is only tens of femtoliters. The small droplets cool quickly during the transfer process, resulting in an extremely short liquid phase time for the droplets deposited on the receptor substrate, making it impossible to achieve effective interface filling and metallurgical bonding. As a result, a large number of defects such as holes and amorphous layers exist within the formed metal transfer structure and at its interface with the receptor substrate, significantly increasing the resistivity of the metal transfer structure. In addition, according to existing research (Conductivity of laser printed copper structures limited by nano-crystal grain size and amorphous metal droplet shell), the research on laser-induced transfer copper film molding structures has shown that the porosity of the molded metal transfer structure is about 4-15%. At the same time, there are a large number of nanocrystals and amorphous materials inside it, which makes the resistivity of the structure as high as 6.9-17.2μΩ·cm, which is more than 4 times that of bulk copper.

[0006] Summary of the Invention

[0007] The purpose of the present invention is to propose a laser-induced forward transfer method for forming a highly conductive metal structure. By adding a thermal annealing step to the transfer method and optimizing the hierarchical structure of the transfer metal layer used for induced transfer, it is beneficial to obtain a metal transfer structure with low porosity and low resistivity, thereby overcoming the shortcomings of the prior art.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] A laser-induced forward transfer method for forming a highly conductive metal structure comprises the following steps:

[0010] A. Prepare the metal transfer film and receptor substrate;

[0011] B. applying a transfer laser to the metal transfer film and depositing it on top of the receptor substrate to form an intermediate structure;

[0012] C. heating the intermediate structure in step B to above 800° C. and cooling it to obtain a metal transfer structure;

[0013] In step A, the metal transfer film includes a transparent substrate and a transfer metal layer bonded to each other; the outer surface of the transparent substrate is used to directly contact the transfer laser, and the transfer metal layer includes copper and silver, and the silver content of the transfer metal layer is 5-95% by mass;

[0014] The transfer metal layer includes at least two transfer films, and the transfer film in contact with the inner surface of the transparent substrate is a copper film or a copper alloy film; in terms of mass percentage, the copper content of the copper alloy film is ≥70%.

[0015] Preferably, the silver content of the transfer metal layer is 71-73% by mass.

[0016] Preferably, the thickness of the transfer film in contact with the inner surface of the transparent substrate is ≤100 nm.

[0017] Preferably, the transfer metal layer includes a first transfer film and a second transfer film, and the first transfer film is in contact with the inner surface of the transparent substrate;

[0018] The second transfer film is a silver film or a silver alloy film; in terms of mass percentage, the silver content of the silver alloy film is ≥70%.

[0019] Preferably, the wavelength of the transfer laser is 300-600 nm.

[0020] Preferably, the absorbance of the transparent substrate to the transfer laser is not higher than 10%.

[0021] Preferably, the transparent substrate comprises any one of fluoride glass, quartz glass, sapphire glass, soda-lime glass and silicate glass.

[0022] The technical solution provided by the embodiment of the present invention may have the following beneficial effects:

[0023] 1. By adding a thermal annealing step to the transfer method, the intermediate structure deposited on top of the acceptor substrate is subjected to a relatively low-temperature heat treatment. This allows the deposited intermediate structure to be partially remelted or undergo atomic diffusion without damaging the acceptor substrate material. The remelted liquid metal, under the action of capillary forces, fills the internal pores of the structure, eliminating defects and significantly improving conductivity. Furthermore, because atoms within the copper-silver alloy diffuse easily and rapidly, this facilitates a rapid increase in grain size and a rapid reduction in grain boundary area, further reducing the resistivity of the metal-transferred structure.

[0024] 2. Optimizing the hierarchical structure of the transfer metal layer used for laser-induced transfer is beneficial for obtaining a metal transfer structure with a low-melting-point copper-silver alloy component. On the other hand, it is also beneficial for improving the light absorption rate of the metal transfer diaphragm to the transfer laser, realizing high energy utilization of the transfer laser in laser transfer, and improving the forming efficiency of the laser-induced transfer technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG1 is a schematic diagram of a partial structure of an intermediate structure in a laser-induced forward transfer method for forming a highly conductive metal structure according to the present invention.

[0026] FIG2 is a schematic diagram of a partial structure of a metal transfer structure in a laser-induced forward transfer method for forming a highly conductive metal structure according to the present invention.

[0027] FIG3 is a schematic diagram of the hierarchical structure of a metal transfer film in a laser-induced forward transfer method for forming a highly conductive metal structure according to the present invention.

[0028] FIG4 is a schematic diagram showing the changes of the surface temperature of the intermediate structure and the surface temperature of the receptor substrate obtained in Example 1 and Comparative Example 1 over time.

[0029] FIG5 is a schematic diagram of the size of the molten pool formed on the metal transfer film in Example 1 and Comparative Example 2 after the transfer laser is incident.

[0030] FIG6 is a schematic diagram of transferred droplets and single lines obtained from the metal transfer films in Example 1 and Comparative Example 2 after the transfer laser is incident.

[0031] FIG7 is a schematic diagram of the size of the molten pool formed on the metal transfer film in Example 1 and Comparative Example 3 after the transfer laser is incident.

[0032] Among them, there are a transparent substrate 1, a transfer metal layer 2, a first transfer film 201, and a second transfer film 202. DETAILED DESCRIPTION

[0033] The present technical solution provides a laser-induced forward transfer method for forming a highly conductive metal structure, comprising the following steps:

[0034] A. Prepare the metal transfer film and receptor substrate;

[0035] B. applying a transfer laser to the metal transfer film and depositing it on top of the receptor substrate to form an intermediate structure;

[0036] C. heating the intermediate structure in step B to above 800° C. and cooling it to obtain a metal transfer structure;

[0037] In step A, the metal transfer film includes a transparent substrate 1 and a transfer metal layer 2 bonded to each other; the outer surface of the transparent substrate 1 is directly exposed to the transfer laser (i.e., the transfer laser sequentially passes through the outer and inner surfaces of the transparent substrate 1 and irradiates the transfer metal layer 2); the transfer metal layer 2 includes copper and silver, and the silver content of the transfer metal layer 2 is 5 to 95% by mass;

[0038] The transfer metal layer 2 includes at least two transfer films, and the transfer film in contact with the inner surface of the transparent substrate 1 is a copper film or a copper alloy film; in terms of mass percentage, the copper content of the copper alloy film is ≥70%.

[0039] In order to obtain a metal transfer structure with low porosity and low resistivity, this technical solution proposes a laser-induced forward transfer method for forming a highly conductive metal structure, which mainly includes two processes: transfer (i.e., step B) and thermal annealing (i.e., step C).

[0040] Since copper and silver are used as transfer metals in the laser-induced forward transfer method of this scheme, the copper-silver alloy structure formed during the transfer process has a low melting point and the internal atomic diffusion rate is faster at the same temperature. Therefore, this scheme adds a thermal annealing step to the transfer method to perform a low-temperature heat treatment on the intermediate structure deposited on top of the receptor substrate. On the basis of not damaging the receptor substrate material, the deposited intermediate structure can be partially remelted and atoms can be diffused. The remelted liquid metal fills the internal pores of the structure under the action of capillary force, eliminates defects, and greatly improves the conductive performance, as shown in Figures 1-2 (Figure 1 is a partial schematic diagram of the intermediate structure before the thermal annealing step, and Figure 2 is a partial schematic diagram of the metal structure after the thermal annealing step). In addition, since the internal atoms of the copper-silver alloy are easy to diffuse and the diffusion rate is relatively fast, it is conducive to the rapid increase of its grain size and the rapid reduction of the grain boundary area, thereby further reducing the resistivity of the metal transfer structure.

[0041] Furthermore, in order to improve the conductivity of the metal transfer structure, this solution also optimizes the hierarchical structure of the transfer metal layer used for metal transfer. On the one hand, it is beneficial to obtain a metal transfer structure with a low melting point copper-silver alloy component. On the other hand, it is also beneficial to improve the light absorption rate of the metal transfer film to the transfer laser, thereby realizing high energy utilization of the transfer laser during the laser transfer process and improving the forming efficiency of the laser induced transfer technology.

[0042] It should be noted that the "copper and silver" in the transfer metal layer 2 comprising copper and silver refers to the copper element and the silver element. For example, the copper element can exist in the form of copper alone or copper atoms in an alloy. Furthermore, in the laser-induced forward transfer method of this embodiment, the order of executing steps B and C can be adjusted according to actual conditions. Step B can be executed first, followed by step C, or steps B and C can be performed alternately, without limitation herein.

[0043] It should be further explained that this solution does not limit the heating method of the intermediate structure in step C. The acceptor substrate and the intermediate structure in step B can be heated as a whole by a vacuum furnace, or the intermediate structure can be locally heated by a laser. When local heating is achieved by laser, the pulsed laser beam used in step B can be used, or a laser beam with other parameters can be used.

[0044] In a preferred embodiment of the present technical solution, the silver content of the transfer metal layer 2 is preferably set to 71-73%, which is more conducive to obtaining a eutectic alloy with a lower melting point and further reducing the resistivity of the metal transfer structure.

[0045] To further illustrate, the thickness of the transfer film in contact with the inner surface of the transparent substrate 1 is ≤100 nm.

[0046] In another preferred embodiment of the present technical solution, the thickness of the transfer film in contact with the inner surface of the transparent substrate 1 is preferably ≤100 nm, which is conducive to the sufficient mixing and alloying of the copper and silver elements during the transfer, thereby forming low-melting-point, highly conductive alloy droplets.

[0047] To further illustrate, the transfer metal layer 2 includes a first transfer film 201 and a second transfer film 202 , and the first transfer film 201 is in contact with the inner surface of the transparent substrate 1 ;

[0048] The second transfer film 202 is a silver film or a silver alloy film; in terms of mass percentage, the silver content of the silver alloy film is ≥70%.

[0049] In one embodiment, the metal transfer film of the present scheme includes a transparent substrate 1, a first transfer film 201 and a second transfer film 202 from top to bottom, wherein the first transfer film 201 is a copper film or a copper alloy film with a copper content ≥ 70%, and the second transfer film 202 is a silver film or a silver alloy film with a silver content ≥ 70%, as shown in Figure 3. This is conducive to further improving the forming efficiency of the laser induced transfer technology while ensuring that a highly conductive metal structure is obtained.

[0050] To further illustrate, the wavelength of the transfer laser is 300-600 nm.

[0051] Using the transfer laser in the above wavelength range is more conducive to improving the light absorption rate of the metal transfer diaphragm of this solution to the transfer laser, thereby achieving a more stable laser transfer molding process.

[0052] To further illustrate, the light absorption rate of the transparent substrate 1 to the transfer laser is not higher than 10%.

[0053] It should be noted that the absorbance refers to the light absorption rate of the transparent substrate 1 to the transferred laser light.

[0054] To further illustrate, the transparent substrate 1 includes any one of fluoride glass, quartz glass, sapphire glass, soda-lime glass and silicate glass.

[0055] The technical solution of the present invention is further illustrated below through specific implementation methods.

[0056] Example 1

[0057] A. Prepare a metal transfer film (1) and a polyimide receptor substrate (thermal decomposition temperature is 400-500° C.);

[0058] B. applying a transfer laser with a wavelength of 532 nm to the metal transfer film (1) and depositing it on top of the polyimide receptor substrate to form an intermediate structure;

[0059] C. Call another pulsed laser with a wavelength of 1064nm and focus the laser on the surface of the intermediate structure to locally heat the intermediate structure in step B at 4.2J / cm 2 The pulse energy density was set to 100 mm / s for one scan, so that the surface temperature of the intermediate structure reached 800°C and the surface temperature of the polyimide receptor substrate was lower than 400°C. After cooling, the metal transfer structure was obtained.

[0060] In this embodiment, the order of performing step B and step C of the laser-induced forward transfer method is: first perform step B several times, and then perform step C once after a complete metal three-dimensional structure is formed on the receptor substrate.

[0061] The hierarchical structure of the metal transfer film (1) is shown in the following table from top to bottom:

[0062] The porosity and resistivity of the intermediate structure obtained in step B and the metal transfer structure obtained in step C of Example 1 were measured. The intermediate structure had a porosity of 10% and a resistivity of 9.24 μΩ·cm. The metal transfer structure formed by the laser-induced forward transfer method of Example 1 had a lower porosity and excellent conductivity, with a porosity of 5% and a resistivity of 4.55 μΩ·cm.

[0063] Example 2

[0064] A. preparing a metal transfer film (2) and a metal copper receptor substrate;

[0065] B. applying a transfer laser with a wavelength of 355 nm to the metal transfer film (2) and depositing it on top of the metal copper receptor substrate to form an intermediate structure;

[0066] C. The metal copper acceptor substrate with the intermediate structure deposited thereon is placed in a vacuum furnace for heating, heated to 850° C. and maintained for 5 minutes, and then cooled to obtain the metal transfer structure.

[0067] In this embodiment, the order of performing step B and step C of the laser-induced forward transfer method is: first perform step B several times, and then perform step C once after a complete metal three-dimensional structure is formed on the receptor substrate.

[0068] The hierarchical structure of the metal transfer film (2) is shown in the following table from top to bottom:

[0069] The porosity and resistivity of the intermediate structure obtained in step B and the metal transfer structure obtained in step C of Example 2 were measured. The intermediate structure had a porosity of 12% and a resistivity of 10.45 μΩ·cm. The metal transfer structure formed by the laser-induced forward transfer method of Example 2 had a lower porosity and excellent conductivity, with a porosity of 5.5% and a resistivity of 4.18 μΩ·cm.

[0070] Example 3

[0071] A. preparing a metal transfer film (3) and a metal copper receptor substrate;

[0072] B. applying a transfer laser with a wavelength of 532 nm to the metal transfer film (3) and depositing it on top of the metal copper receptor substrate to form an intermediate structure;

[0073] C. Use the transferred laser with a wavelength of 532 nm in step B to locally heat the intermediate structure in step B in a defocused state, scanning five times with a pulse energy of 5 uJ and a scanning speed of 100 mm / s to make the surface temperature of the intermediate structure reach 800°C.

[0074] In this embodiment, the order of performing step B and step C of the laser-induced forward transfer method is: step B and step C are performed alternately until a complete metal transfer structure is formed on the receptor substrate.

[0075] The hierarchical structure of the metal transfer film (3) is shown in the following table from top to bottom:

[0076] The metal transfer structure formed by the laser-induced forward transfer method of Example 3 has a small porosity and excellent electrical conductivity. The porosity is 4% and the resistivity is 3.9 μΩ·cm.

[0077] Comparative Example 1

[0078] A. Prepare a metal transfer film (4) and a polyimide receptor substrate (thermal decomposition temperature is 400-500° C.);

[0079] B. applying a transfer laser with a wavelength of 532 nm to the metal transfer film (4) and depositing it on top of the polyimide receptor substrate to form an intermediate structure;

[0080] C. Call another pulsed laser with a wavelength of 1064nm and focus the laser on the surface of the intermediate structure to locally heat the intermediate structure in step B at 5.2J / cm 2 The pulse energy density was 100 mm / s and the scanning speed was 100 mm / s. The surface temperature of the intermediate structure reached 1100 °C, and the metal transfer structure was obtained after cooling.

[0081] In this comparative example, the order of performing steps B and C of the laser-induced forward transfer method is: first perform step B several times, and then perform step C once after a complete metal three-dimensional structure is formed on the receptor substrate.

[0082] The hierarchical structure of the metal transfer film (4) is shown in the following table from top to bottom:

[0083] It should be noted that due to the high melting point of metallic copper, at 1083°C, the temperature of the intermediate structure surface during pulsed laser irradiation in step C was controlled at 1100°C to achieve a localized remelting effect. The metal transfer structure formed by the laser-induced forward transfer method of Comparative Example 1 had a porosity of 6% and a resistivity of 5.2 μΩ·cm.

[0084] Figure 4 shows the intermediate structure obtained in Example 1 (i.e., a three-dimensional copper-silver alloy structure) and the intermediate structure obtained in Comparative Example 1 (i.e., a three-dimensional copper structure). The surface temperature of the intermediate structure and the receptor substrate surface temperature change over time after local heating in Step C are shown. Because copper metal requires a higher remelting temperature than copper-silver alloy, the temperature distribution diagram shows that when the surface temperature of the three-dimensional structure composed of pure copper reaches 1083°C, subsequent heat conduction causes the temperature of the receptor surface to rise to 500°C, which is far higher than the thermal decomposition temperature of the polyimide receptor substrate, which is 400°C. Therefore, when the material used to construct the intermediate structure has a high melting point, the high temperature required during the thermal annealing process can easily damage the receptor substrate.

[0085] Comparative Example 2

[0086] A. Prepare a metal transfer film (5) and a polyimide receptor substrate (thermal decomposition temperature is 400-500° C.);

[0087] B. applying a transfer laser with a wavelength of 532 nm to the metal transfer film (5) and depositing it on top of the polyimide receptor substrate to form an intermediate structure;

[0088] C. Call another pulsed laser with a wavelength of 1064nm and focus the laser on the surface of the intermediate structure to locally heat the intermediate structure in step B at 4.2J / cm 2 The energy density was set at 100 mm / s and the scanning speed was set at 100 mm / s. The surface temperature of the intermediate structure reached 800°C and the surface temperature of the polyimide receptor substrate was lower than 400°C. After cooling, the metal transfer structure was obtained.

[0089] In this comparative example, the order of performing steps B and C of the laser-induced forward transfer method is: first perform step B several times, and then perform step C once after a complete metal three-dimensional structure is formed on the receptor substrate.

[0090] The hierarchical structure of the metal transfer film (5) is shown in the following table from top to bottom:

[0091] The metal transfer structure formed by the laser induced forward transfer method of Comparative Example 2 had a porosity of 6% and a resistivity of 5.87 μΩ·cm.

[0092] As shown in Figure 5, it is a schematic diagram of the size of the molten pool formed by the metal transfer film (1) of Example 1 and the metal transfer film (5) of Comparative Example 2 after the transfer laser is incident. After comparing the numerical analysis results, it is found that the volume of the molten pool formed by the metal transfer film (1) after the transfer laser is incident is 3 times the volume of the molten pool formed by the metal transfer film (5) after the transfer laser is incident.

[0093] As shown in FIG6 , the transfer droplets and single lines obtained by the metal transfer film (1) of Example 1 and the metal transfer film (5) of Comparative Example 2 after the transfer laser is incident are schematically shown; wherein, FIG6(a) is a schematic diagram of the transfer droplets obtained by the metal transfer film (1) of Example 1 after the transfer laser is incident, and FIG6(b) is a schematic diagram of the transfer droplets obtained by the metal transfer film (5) of Comparative Example 2 after the transfer laser is incident; FIG6(c) is a schematic diagram of the single line obtained by the metal transfer film (1) of Example 1 after the transfer laser is incident, and FIG6(d) is a schematic diagram of the single line obtained by the metal transfer film (5) of Comparative Example 2 after the transfer laser is incident. That is, after the transfer laser is incident, the transfer droplets obtained by the metal transfer film (1) of Example 1 are larger than the transfer droplets obtained by the metal transfer film (5) of Comparative Example 2, and the width of the single line obtained by the metal transfer film (1) of Example 1 is larger than the width of the single line obtained by the metal transfer film (5) of Comparative Example 2.

[0094] In summary, this scheme optimizes the hierarchical structure of the transfer metal layer used for metal transfer, which is beneficial to improving the light absorption rate of the metal transfer diaphragm to the transfer laser, realizing high energy utilization of the transfer laser in laser transfer, and improving the forming efficiency of the laser induced transfer technology.

[0095] Comparative Example 3

[0096] A. Prepare a metal transfer film (6) and a polyimide receptor substrate (thermal decomposition temperature is 400-500° C.);

[0097] B. Apply transfer laser with a wavelength of 532 nm to the metal transfer film (6).

[0098] The hierarchical structure of the metal transfer film (6) is shown in the following table from top to bottom:

[0099] FIG7 shows a schematic diagram of the size of the molten pool formed by the metal transfer film (1) of Example 1 and the metal transfer film (6) of Comparative Example 3 after the transfer laser is incident. After comparing the numerical analysis results, it is found that the volume of the molten pool obtained by using the metal transfer film (1) is 3.5 times the volume of the molten pool obtained by using the metal transfer film (6). At the same time, it can be observed that under the pulse energy of 0.5uJ, the internal molten pool of the metal transfer film (1) completely penetrates the upper and lower surfaces of the transfer metal layer, while under the same pulse energy, the front edge of the internal molten pool of the metal transfer film (6) only reaches the surface of the copper film and does not completely penetrate the interior of the transfer metal layer. This means that under the laser irradiation of this pulse energy, the metal transfer film (6) will not form a metal transfer.

[0100] The technical principles of the present invention have been described above with reference to specific embodiments. These descriptions are intended solely to illustrate the principles of the present invention and are not to be construed in any way as limiting the scope of protection of the present invention. Based on the explanations herein, those skilled in the art will readily conceive of other specific embodiments of the present invention without inventive effort, and such embodiments will fall within the scope of protection of the present invention.

Claims

1. A laser induced forward transfer method for forming a highly conductive metal structure, characterized in that: The following steps are involved: A. Prepare metal transfer membrane and receptor substrate; B. applying a transfer laser to the metal transfer film and depositing it on the top of the receptor substrate to form an intermediate structure; C. heating the intermediate structure in step B to above 800° C. and cooling to obtain a metal transfer structure; In step A, the metal transfer film comprises a transparent substrate and a transfer metal layer which are bonded to each other; the outer surface of the transparent substrate is used to directly contact the transfer laser, the transfer metal layer comprises copper and silver, and the silver content of the transfer metal layer is 5 to 95% by mass; The transfer metal layer comprises at least two layers of transfer films, and the transfer film in contact with the inner surface of the transparent substrate is a copper film or a copper alloy film; in terms of mass percentage, the copper content of the copper alloy film is ≥70%.

2. A laser induced forward transfer method for forming a highly conductive metal structure according to claim 1, characterized in that: According to mass percentage, the silver content of the transfer metal layer is 71-73%.

3. The laser induced forward transfer method for forming a highly conductive metal structure according to claim 1, characterized in that: The thickness of the transfer film in contact with the inner surface of the transparent substrate is ≤100 nm.

4. The laser induced forward transfer method for forming a highly conductive metal structure according to claim 1, characterized in that: The transfer metal layer includes a first transfer film and a second transfer film, and the first transfer film is in contact with the inner surface of the transparent substrate; The second transfer film is a silver film or a silver alloy film; According to mass percentage, the silver alloy The silver content of the film is ≥70%.

5. The laser induced forward transfer method for forming a highly conductive metal structure according to claim 1, characterized in that: The light absorption rate of the transparent substrate to the transfer laser is not higher than 10%.

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