Evaporation method and application thereof

Abstract

The invention provides an evaporation method and application thereof, and relates to the technical field of vacuum evaporation, the evaporation method comprises the following steps: preheating an evaporation boat, a tungsten mesh and a solid aluminum source arranged on the tungsten mesh; pre-melting treatment is conducted, the solid aluminum source is melted, and molten aluminum covering part of the surface of the tungsten net is formed; pre-evaporation treatment is conducted, the molten aluminum is evaporated, and an initial infiltration area is formed; in the primary wire feeding stage, aluminum wires are fed at the first wire feeding speed, molten aluminum obtained after the aluminum wires are molten is spread in the initial infiltration area till the tungsten mesh is completely infiltrated by the molten aluminum, and at least part of the tungsten mesh is consumed; in the secondary wire feeding stage, aluminum wires are fed at the second wire feeding speed, and the tungsten net is completely consumed; and an evaporation stage: evaporating an aluminum metal layer on the base film. According to the evaporation method provided by the invention, the spreading uniformity and evaporation stability of the molten aluminum are improved, and the technical problems of narrow liquid level, frequent splashing and non-uniform coating thickness caused by non-uniform heat distribution in the traditional process are solved.

Description

Technical Field

[0001] This invention relates to the field of vacuum evaporation technology, and in particular to an evaporation method and its application. Background Technology

[0002] In vacuum evaporation deposition of aluminum films, especially in the production of composite current collectors, the uniformity and stability of the molten aluminum spread within the evaporation boat directly determine the evaporation efficiency and coating quality. In the vacuum evaporation process of composite current collectors (such as aluminum deposition on polymer base films like PET / PP), a heating method with multiple evaporation boats arranged densely is often employed.

[0003] Currently, due to intense heat radiation between the boats, the temperature at the edge of the evaporation boat is much higher than the temperature in the central area where the molten aluminum is cooled. The molten aluminum cannot spread to the high-temperature edge within the boat due to the Malagni effect (thermocapillary effect), resulting in problems such as a narrow liquid surface, small evaporation area, poor uniformity of vapor deposition, and low efficiency. Furthermore, the uneven distribution of the molten aluminum easily leads to splashing.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] One of the objectives of this invention is to provide an aluminum vapor deposition method based on a tungsten mesh evaporation boat, so as to at least solve one of the technical problems existing in the prior art.

[0006] The second objective of this invention is to provide an application of an aluminum vapor deposition method based on a tungsten mesh evaporation boat in the preparation of composite current collectors.

[0007] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: In a first aspect, the present invention provides a vapor deposition method, comprising the following steps: A tungsten mesh is placed in a material trough on the upper surface of an evaporation boat. A solid aluminum source is placed on the tungsten mesh. The evaporation boat, the tungsten mesh, and the solid aluminum source on the tungsten mesh are preheated to remove gas and moisture from the evaporation boat, the tungsten mesh, and the solid aluminum source. The pre-melting process melts the solid aluminum source to form molten aluminum covering part of the tungsten mesh surface; The pre-evaporation treatment causes the molten aluminum to evaporate, forming an initial wetting area; In the first wire feeding stage, aluminum wire is fed in at the first wire feeding rate. The molten aluminum wire spreads in the initial wetting area until the tungsten mesh is completely wetting by the molten aluminum, and the tungsten mesh is at least partially consumed. In the secondary wire feeding stage, aluminum wire is fed in at the second wire feeding rate, and the tungsten mesh is completely consumed. In the vapor deposition stage, an aluminum metal layer is vapor deposited onto the base film.

[0008] Furthermore, the tungsten mesh is embedded in the bottom of the material-holding trough on the upper surface of the evaporation boat; Preferably, the tungsten mesh has a mesh count of 18-300 meshes per inch and a wire diameter of 0.06 mm-0.2 mm.

[0009] Furthermore, the volume ratio of the solid aluminum source to the material container on the upper surface of the evaporation boat is 4-6:100; Preferably, the solid aluminum source includes one or both of aluminum sheets and aluminum wires.

[0010] Furthermore, the first wire feeding rate is less than the second wire feeding rate.

[0011] Furthermore, during the preheating process, the power of the preheating evaporation source is no more than 50% of the total power of the evaporation source; Preferably, the preheating time is 15-25 minutes.

[0012] Furthermore, during the pre-melting process, the evaporation source power is 65%-75% of the total evaporation source power. Preferably, the pre-melting treatment time is 10-20 min.

[0013] Furthermore, during the pre-evaporation process, the power of the evaporation source is 80%-85% of the total power of the evaporation source. Furthermore, the vapor deposition method also satisfies at least one of the following conditions: (1) In the first wire feeding stage, the evaporation source power in the first wire feeding stage is 89%-92% of the total evaporation source power; Optionally, the duration of the single wire feeding stage is 3-8 minutes; Optionally, the first wire feeding rate is 150-200 mm / min; (2) In the secondary wire feeding stage, the evaporation source power in the secondary wire feeding stage is 90-92% of the total evaporation source power; Optionally, the duration of the secondary wire feeding stage is 3-8 minutes; Optionally, the second wire feeding rate is 350-450 mm / min.

[0014] Furthermore, during the vapor deposition stage, the power of the evaporation source in the vapor deposition stage is 87%-89% of the total power of the evaporation source.

[0015] Secondly, the present invention provides an application of the vapor deposition method described above in the preparation of composite current collectors.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The vapor deposition method provided by this invention comprises steps that cooperate with each other and proceed step by step. Preheating treatment: removes adsorbed moisture and gas from the material to avoid subsequent gas release disturbances to the vacuum and prevent boiling over. Pre-melting treatment: melts the aluminum source under controlled temperature rise, and relies on the porous structure and capillary action of the tungsten mesh to form a layer of molten aluminum covering part of the tungsten mesh surface, expanding the initial evaporation area and inhibiting droplet aggregation. Pre-evaporation treatment completely vaporizes the molten aluminum, simultaneously reducing and removing the oxide layer on the tungsten mesh surface, exposing a clean, active tungsten surface, and generating AlN in situ at the boron nitride boat interface, forming the initial wetting area. In the first wire feeding stage, the first wire feeding is at a first speed... The introduction of aluminum wire allows the freshly molten aluminum to rapidly wet the surface of the activated tungsten mesh, resulting in interfacial interactions that significantly improve wettability, drive spreading, and simultaneously initiate the aluminum-tungsten reaction, achieving partial consumption of the tungsten mesh and tight adhesion between the boat and the mesh. In the secondary wire feeding stage, the increased feeding rate enhances the scouring force of the molten aluminum, completely stripping away residual tungsten mesh and brittle reaction products, which are then migrated and enriched at the edge of the tank. This not only completes the consumption of the tungsten mesh but also forms a natural barrier zone to stabilize the evaporation front. The vapor deposition stage is carried out under the previously established conditions of uniform spreading, interface stability, and controlled impurities in the molten aluminum. The vapor deposition method provided by this invention improves the uniformity of molten aluminum spreading and evaporation stability, solving the technical problems of narrow liquid surface, frequent splashing, and uneven coating thickness caused by uneven heat distribution in traditional processes. Attached Figure Description

[0017] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 A process flow diagram of the vapor deposition method provided by the present invention; Figure 2 This is a top view of the evaporation boat for the vapor deposition method provided by the present invention.

[0019] Illustration: 10 - Evaporation boat; 20 - Tungsten mesh. Detailed Implementation

[0020] Unless otherwise defined herein, the scientific and technical terms used in conjunction with this invention shall have the meanings commonly understood by one of ordinary skill in the art. The meaning and scope of terms shall be clear; however, in any case of potential ambiguity, the definitions provided herein shall prevail over any dictionary or foreign definitions. In this application, unless otherwise stated, the use of "or" means "and / or". Furthermore, the use of the term "comprising" and other forms is non-limiting.

[0021] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] like Figure 1 As shown, the first aspect of the present invention provides a method for aluminum vapor deposition in an evaporation boat based on a tungsten mesh, comprising the following steps: S1, such as Figure 2 As shown, a tungsten mesh 20 is placed in a material container on the upper surface of the evaporation boat 10. A solid aluminum source is placed on the tungsten mesh. The evaporation boat, the tungsten mesh, and the solid aluminum source placed on the tungsten mesh are preheated to remove gas and moisture from the evaporation boat, the tungsten mesh, and the solid aluminum source. S2. Pre-melting treatment, which melts the solid aluminum source to form molten aluminum covering part of the surface of the tungsten mesh; S3. Pre-evaporation treatment, which causes the molten aluminum to evaporate and form an initial wetting area; S4. In the first wire feeding stage, aluminum wire is fed in at the first wire feeding rate. The molten aluminum wire spreads in the initial wetting area until the tungsten mesh is completely wetting by the molten aluminum, and the tungsten mesh is at least partially consumed. S5. Secondary wire feeding stage: Aluminum wire is fed in at the second wire feeding rate, and the tungsten mesh is completely consumed. S6. In the vapor deposition stage, it is preferable to maintain the second wire feeding rate to vapor deposit an aluminum metal layer on the base film.

[0023] This invention specifically relates to a process for aluminum vapor deposition using an evaporation boat with a tungsten mesh in the production of composite current collectors. By placing the tungsten mesh inside the evaporation tank of the evaporation boat, the porous tungsten mesh increases the surface area. Under the action of capillary force, the aluminum liquid spreads more easily along the pores and surface of the tungsten mesh. Through process control, the maximum spreading state of the aluminum liquid is achieved, improving evaporation efficiency, facilitating the formation of a uniform aluminum liquid, and eliminating splashing caused by droplet aggregation and breakage due to uneven liquid surface spreading.

[0024] In some preferred embodiments, a tungsten mesh is embedded in the material-holding tank (hereinafter referred to as the evaporation tank) on the upper surface of the evaporation boat. The tungsten mesh has a mesh count of 18 to 300 meshes per inch and a wire diameter of 0.06 mm to 0.2 mm. If the mesh count of the tungsten mesh is too low (<18 mesh), the pores will be too large, the capillary driving force will be insufficient, and the aluminum liquid will easily agglomerate into droplets instead of forming a film. If the mesh count is too high (>300 mesh), the porosity will decrease and the flow resistance will increase. Furthermore, if the wire diameter is too thin, the resistance to melting and corrosion at high temperatures will decrease, and it will be prone to local breakage. The 0.06-0.2 mm wire diameter of the tungsten mesh in this invention, combined with the 18-300 mesh range, can maintain the integrity of the tungsten mesh structure while ensuring sufficient specific surface area and capillary lift.

[0025] In some preferred embodiments, the volume ratio of solid aluminum source to evaporation tank is (4-6):100. When this volume ratio is below 4:100, the amount of molten aluminum is insufficient to fully fill the pores of the tungsten mesh and cover its surface through capillary action, resulting in a discontinuous and uneven initial wetting zone. This is detrimental to the formation of an effective initial wetting area after the solid aluminum source is evaporated, disrupting the continuity of subsequent wetting. When the volume ratio is above 6:100, excessive aluminum accumulation occurs. On the one hand, this may cause excessive aluminum to overflow from the evaporation tank; on the other hand, melting excessive aluminum requires more energy and time, prolonging the initial stage of the process. Furthermore, excessive initial aluminum may cause the tungsten mesh to be consumed or encased too quickly, hindering the subsequent spreading of the aluminum. Therefore, the above volume ratio range ensures that the molten aluminum just wets and covers the central area of ​​the tungsten mesh, preventing excessive overflow of the evaporation tank after melting. Here, "4-6" can be, for example, 4, 5, or 6.

[0026] In some preferred embodiments, the solid aluminum source includes one or both of aluminum sheets and aluminum wires. In this invention, tungsten mesh and aluminum sheets are stacked in the evaporation tank of an evaporation boat. The tungsten mesh is embedded at the bottom of the evaporation tank, covering the bottom of the tank, and the aluminum sheets are placed on the tungsten mesh. Alternatively, aluminum wires can be cut into sections, bent, and placed on the tungsten mesh.

[0027] Specifically, the contact area between the aluminum sheet and the tungsten mesh is typically larger and more closely fitted than that of the aluminum wire. This facilitates a more uniform and rapid transfer of heat from the tungsten mesh to the aluminum, reducing localized overheating and resulting in a smoother and more uniform initial melting process for the aluminum. It also helps to form a more continuous and stable initial wetting zone, laying a better foundation for subsequent capillary spreading. The aluminum wire is a commonly used consumable in vapor deposition and does not require customization; the aluminum wire commonly used in the production line can be directly used as the initial material, saving costs.

[0028] In some preferred embodiments, during the preheating treatment, the power of the evaporation source is no more than 50% of the total power of the evaporation source. At this power, through a certain period of preheating, gases from the evaporation boat, tungsten mesh, and solid aluminum source are expelled, ensuring the stability of the evaporation environment. This step is one of the most important technical effects of preheating. Furthermore, preheating the evaporation boat stabilizes its temperature, preventing it from cracking due to a rapid temperature increase, which would affect its use. The total power of the evaporation source is 5-8 kW, and the value of the total power includes, but is not limited to, 5 kW, 6 kW, 7 kW, 8 kW, or any range between the aforementioned. It should be noted that the total power is generally the rated power, but it can be adjusted according to actual conditions to make the total power lower than the rated power. Additionally, the power of each evaporation boat can be independently controlled.

[0029] In some preferred embodiments, during the pre-melting treatment, the power of the evaporation source is 65%-75% of the total power of the evaporation source, for example, 65%, 70%, 75%, etc. This power range allows the solid aluminum source to be fully melted, forming an aluminum liquid film covering the surface and pores of the tungsten mesh. When the power is below 65%, the aluminum source is not completely melted, and the aluminum liquid cannot spread continuously; when it is above 75%, the aluminum liquid is locally overheated, generating bubbles, destroying the integrity of the liquid film, and ultimately affecting the continuity of the initial wetting area.

[0030] Specifically, by controlling the power of the evaporation source in the pre-melting treatment to increase at a rate of 0.1% / s to 0.2% / s to 65%-75% of the total power of the evaporation source, the power increase rate is within this range, which can ensure the melting efficiency of the solid aluminum source and also help ensure the stability of the evaporation boat, preventing damage to the evaporation boat due to excessive speed.

[0031] In some preferred embodiments, during the pre-evaporation treatment, the evaporation source power is 80%-85% of the total evaporation source power, for example, 80%, 81%, 82%, 83%, 84%, 85%, etc. This power range ensures complete evaporation of the molten aluminum, and both the initial aluminum wire and tungsten mesh surfaces have a dense oxide film. When heated to a high temperature, liquid aluminum acts as a strong reducing agent, reacting with the tungsten oxide on the tungsten mesh surface. This reaction removes the oxide from the tungsten mesh surface, exposing a clean tungsten mesh surface. The clean metal surface significantly reduces the interfacial energy, making it easier for the molten aluminum to spread after melting during subsequent wire feeding. Furthermore, the main material of the evaporation boat is boron nitride. The molten aluminum reacts fully with the surface of the evaporation boat tank to generate aluminum nitride, forming an interface region with enhanced wettability, thus forming the initial wetting zone. When the power is below 80%, the molten aluminum cannot evaporate completely, affecting subsequent wetting; when it is above 85%, the molten aluminum evaporates too quickly and cannot fully react on the tank surface to generate aluminum nitride.

[0032] In some preferred embodiments, the evaporation source power during the first wire feeding stage is 89%-92% of the total evaporation source power, for example, 89%, 90%, 91%, 92%, etc. This power range allows the freshly molten aluminum to rapidly wet the surface of the clean tungsten mesh and spread quickly in the initial wetting zone. Under the action of capillary force, the aluminum liquid spreads along the pores and surface of the tungsten mesh, and the tungsten mesh is completely wetted into the aluminum liquid, undergoing an interfacial reaction with the aluminum liquid and at least partially consuming the tungsten mesh. When the power is below 89%, the evaporation boat temperature is insufficient, the amount of aluminum liquid melted is insufficient, resulting in poor aluminum liquid fluidity, slow wetting, and incomplete reaction; when the power is above 92%, the aluminum liquid is overheated, the evaporation rate is too fast, and the tungsten mesh is not completely wetted into the aluminum liquid, resulting in incomplete and uneven consumption of the tungsten mesh, which can easily generate contamination sources that affect subsequent evaporation deposition.

[0033] In some preferred embodiments, the evaporation source power in the secondary wire feeding stage is 90-92% of the total evaporation source power, for example, 90%, 91%, 92%, etc. This power range can maintain sufficient fluidity of the molten aluminum at this wire feeding speed, while ensuring that the molten aluminum does not accumulate excessively, preventing it from overflowing the evaporation boat and causing splashing. On the other hand, it allows the remaining tungsten mesh to react fully with the molten aluminum until it is completely consumed, while simultaneously promoting the migration and accumulation of reaction products and impurities at the edge of the evaporation tank. When the power is below 90%, the aluminum wire melts slowly, resulting in insufficient scouring force of the molten aluminum, and impurities cannot migrate effectively; when the power is above 92%, the boiling of the molten aluminum intensifies, causing greater fluctuations in the liquid surface, which is not conducive to impurity migration.

[0034] In some preferred embodiments, during the vapor deposition stage, the evaporation source power is 87%-89% of the total evaporation source power. This power range keeps the molten aluminum in a stable evaporation state, ensuring uniform aluminum deposition of the base film. When the power is below 87%, the evaporation rate decreases, resulting in uneven film thickness; when the power is above 89%, the molten aluminum temperature is too high, which can easily cause splashing and affect the film quality.

[0035] In this invention, the power settings at each stage work in tandem. From pre-melting to pre-evaporation, the aluminum melt evaporation reaction forms the initial wetting zone and purifies the tungsten mesh interface. From primary to secondary wire feeding, the aluminum melt is spread within the evaporation boat, and the tungsten mesh is consumed while impurities migrate directionally. This entire power gradient avoids the violent fluctuations and splashing of the liquid surface caused by sudden power changes in traditional processes, ensuring the uniformity of aluminum melt spreading and the stability of evaporation.

[0036] In some preferred embodiments, the first wire feeding rate is lower than the second wire feeding rate. By gradually increasing the wire feeding rate, a smooth transition of the wire feeding rate is achieved, avoiding violent fluctuations in the liquid surface caused by sudden changes in the rate when the vapor deposition is started.

[0037] In some preferred embodiments, the first wire feeding rate is 150-200 mm / min. During a single wire feeding stage, aluminum wire is fed in at this rate for melting, the tungsten mesh is completely wetted by the molten aluminum and an interfacial reaction occurs, and at least part of the tungsten mesh is consumed. If the rate is below 150 mm / min, insufficient replenishment of molten aluminum may result in inadequate wetting of the tungsten mesh; if it is above 200 mm / min, the impact force of the molten aluminum is too great, easily causing displacement of the tungsten mesh or localized splashing.

[0038] In some preferred embodiments, the second wire feeding rate is 350-450 mm / min. This rate increases the scouring force of the molten aluminum, ensuring complete consumption of the remaining tungsten mesh, while simultaneously migrating and enriching reaction products and impurities at the edge of the evaporation tank. If the rate is below 350 mm / min, insufficient impurity migration may occur; if it is above 450 mm / min, increased surface disturbance will affect the stability of the liquid surface.

[0039] In this invention, the two rate stages work together with power control to achieve the technical effects of expanding the aluminum liquid spreading area, stabilizing the evaporation front, and achieving uniform coating thickness.

[0040] This invention employs a phased process design. In the primary wire feeding stage, a uniform and dense interfacial reaction layer is established at a moderate rate and power, anchoring the tungsten mesh, enhancing wetting, and promoting spreading. In the secondary wire feeding stage, the rate and power are increased, utilizing the flow of molten aluminum to directionally migrate and enrich reaction products and impurities at the edge of the evaporation tank, forming a stable barrier zone. This prevents molten aluminum from overflowing, ensures a constant shape of the evaporation zone, and effectively expands the evaporation area. Throughout the process, preheating, pre-melting, and pre-evaporation steps ensure a tight fit between the tungsten mesh and the evaporation boat, eliminating poor thermal contact caused by warping and ensuring high consistency in the process state for each batch. The consumption of the tungsten mesh is gradual and controllable, avoiding violent peeling that generates large particles of impurities, significantly improving the cleanliness and thickness uniformity of the coating.

[0041] In a preferred embodiment of the present invention, the aluminum vapor deposition method based on a tungsten mesh evaporation boat includes the following stages performed sequentially: S1. Place the evaporation boat in the vapor deposition equipment, embed a tungsten mesh in the material tank on the upper surface of the evaporation boat, and place aluminum sheets on the tungsten mesh. Preheat the evaporation boat, tungsten mesh and aluminum sheets to remove gas and moisture from the material of the evaporation boat. At this time, adjust the power of the evaporation source to no more than 50% of the total power of the evaporation source. The time of this stage is 15-25 minutes, for example, 15 minutes, 20 minutes, 25 minutes, etc.

[0042] S2. Perform pre-melting treatment, control the power of the evaporation source to 65-75% of the total power of the evaporation source, and increase the power of the evaporation source at a rate of 0.1% per second, and maintain for 10-20 minutes, for example, 10 minutes, 15 minutes, 20 minutes, etc.

[0043] Specifically, the porous tungsten mesh is embedded at the bottom of the evaporation boat, which significantly increases the effective contact area between the liquid aluminum source and the evaporation boat. During the pre-melting stage, the aluminum sheet is heated and melted into a liquid state, while the tungsten mesh remains solid. At this time, under the capillary force generated by the porous structure of the tungsten mesh, the liquid aluminum is more likely to spread along the pores and surface of the tungsten mesh, forming a thin film. This effectively inhibits the liquid aluminum from agglomerating into spheres or accumulating locally due to surface tension, thereby establishing a stable evaporation surface in the evaporation boat. Preferably, the volume ratio of the aluminum sheet or aluminum wire used in S1 and 2 to the volume of the evaporation trough is (4-6):100, so that the molten aluminum can just wet and cover the central area of ​​the tungsten mesh without overflowing.

[0044] S3. Perform pre-evaporation treatment, and control the power of the evaporation source to 80-85% of the total power of the evaporation source.

[0045] Specifically, in the pre-evaporation stage, the spread aluminum liquid is rapidly evaporated at 80%-85% of the total power. This avoids excessive reaction of the tungsten mesh caused by prolonged aluminum liquid residence and allows the aluminum liquid to react in situ with the boron nitride tank of the evaporation boat at high temperature to form aluminum nitride (AlN). This aluminum nitride layer adheres to the surface of the tank, reducing the interfacial energy between the aluminum liquid and the tank, forming an area with enhanced wettability, i.e., the initial wetting area, which is beneficial for the stable spreading of aluminum liquid in the subsequent wire feeding stage. At the same time, the liquid aluminum at high temperature acts as a strong reducing agent, reacting with the tungsten oxide on the surface of the tungsten mesh, removing the oxide layer and exposing a clean, highly active tungsten metal surface, significantly improving the wettability of the aluminum liquid on the tungsten mesh. After the aluminum liquid is completely evaporated, the tungsten mesh remains solid, and due to the filling of the aluminum liquid and its reaction with the evaporation boat tank, the tungsten mesh adheres tightly to the evaporation boat tank, effectively preventing the aluminum liquid from washing the tungsten mesh out of the evaporation boat during the subsequent wire feeding process.

[0046] S4. First wire feeding stage (i.e., slow wire feeding stage): At this time, the first wire feeding speed V1 is controlled to feed the aluminum wire at a speed of 150-200 mm / min, and the power of the evaporation source is controlled to 89-92% of the total power of the evaporation source, and maintained for 3-8 minutes, for example, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, etc.

[0047] Specifically, after the clean tungsten mesh surface is exposed, aluminum wire is continuously fed in at a rate of 150–200 mm / min. The freshly molten aluminum immediately comes into contact with it, forming physical adsorption and short-range chemical bonding between aluminum and tungsten atoms, generating an extremely thin interface layer. This significantly reduces the interfacial tension between the aluminum and the tungsten mesh, increases the bonding work between the aluminum and the solid, leading to a smaller contact angle and significantly improved wettability. At this point, the freshly molten aluminum preferentially spreads rapidly within the initial wetting area formed by S3. As the aluminum continues to melt and drip, it gradually fills the entire evaporation tank under the capillary action of the tungsten mesh, completely wetting the tungsten mesh into the aluminum. Simultaneously, the aluminum further reacts with the tank to form aluminum nitride, expanding wetting. The area enhances overall spreading stability and improves the spreading ability of the aluminum liquid during subsequent coating. Furthermore, the flowing aluminum liquid presses the tungsten mesh, which may slightly warp due to heat, against the bottom of the tank, ensuring complete wetting and participation in the reaction. At 89%-92% power, aluminum and tungsten undergo an interfacial reaction to generate intermetallic compounds such as Al4W. The flowing aluminum liquid washes away and erodes this brittle interfacial reaction layer or the already loosened tungsten surface, achieving gradual consumption of the tungsten mesh. Slow wire feeding ensures a smooth process, preventing the tungsten mesh from being impacted, displaced, or swept out of the evaporation boat, ultimately causing at least partial disappearance of the tungsten mesh, removing potential impurity sources for subsequent stable evaporation.

[0048] S5, Secondary wire feeding stage (i.e., rapid wire feeding stage): At this time, the aluminum wire is fed in at a speed of V2 = 350-450 mm / min, and the power of the evaporation source is controlled to 90-92% of the total power of the evaporation source, and maintained for 3-8 minutes, for example, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, etc.

[0049] Specifically, at 90%-92% power, the molten aluminum maintains good fluidity, coupled with a relatively high wire feed rate of 350–450 mm / min. Increasing the wire feed rate increases the flow rate and momentum of the molten aluminum, which begins to flush the molten aluminum in the evaporation tank. This gradually peels off and carries forward the reaction products (mainly the brittle aluminum-tungsten compound layer) and other impurities generated in stage S4 or S5, pushing the liquid surface spreading front towards the edge of the evaporation boat. This maintains stable evaporation in the evaporation zone, and the reaction products and impurities are pushed to the edge of the evaporation tank, forming a blocking effect to prevent the molten aluminum from overflowing and causing uneven film thickness. Increasing the wire feed rate also allows the wire feed speed to gradually approach the wire feed rate during evaporation, achieving a smooth transition and avoiding violent fluctuations in the liquid surface caused by sudden changes in rate at the start of evaporation. Under these conditions, the tungsten mesh is completely consumed, leaving only uniformly spread molten aluminum in the evaporation tank, laying the foundation for subsequent stable evaporation.

[0050] S6, Evaporation Stage: After the liquid surface stabilizes, maintain the wire feeding rate of S5 and control the evaporation source power to be reduced to 87-89% of the total evaporation source power, such as 87%, 88%, 89%, etc., and start continuous evaporation of the PET base film. Since the evaporation source power has increased to the target power in the S5 stage, although the power has not changed, the temperature of the evaporation boat is still rising. In order to prevent the aluminum liquid from boiling due to higher temperature, the power needs to be reduced to maintain the stability of the evaporation boat temperature and the stability of liquid surface evaporation. At this time, the aluminum liquid spreads over a large area and the aluminum liquid evaporation is stable, which helps to reduce splashing.

[0051] A second aspect of the present invention provides an application of a vapor deposition method in the preparation of composite current collectors.

[0052] The present invention will be further illustrated by the following examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or purchased directly from the market.

[0053] Example 1 This embodiment provides a vapor deposition method, wherein the total power is 6 kW; the vacuum vapor deposition equipment is equipped with a gas analyzer and an image acquisition device; the tungsten mesh has a mesh count of 200 meshes per inch and a wire diameter of 0.08 mm; the vacuum degree is 3 × 10⁻⁶. - 3 Pa, the volume ratio of aluminum sheet to evaporation boat is 5:100; The method includes the following steps: S1: Tungsten mesh and aluminum sheets are stacked in the evaporation tank of the evaporation boat. The tungsten mesh is embedded at the bottom of the evaporation tank, covering the bottom. The aluminum sheets are placed on the tungsten mesh. The evaporation boat, tungsten mesh, and aluminum sheets are preheated in the vapor deposition equipment. The power of the evaporation source is increased to 50% of the total power (3kW). The moisture pressure curve in the chamber is detected by a gas analyzer. When the moisture pressure curve gradually rises and stabilizes, this stage is complete. This stage takes approximately 20 minutes. S2: When the water pressure curve gradually rises to a stable level, pre-melting treatment is performed. The power of the evaporation source is controlled to 70% of the total power of the evaporation source (4.2KW). The power increase rate of the evaporation source is 0.1% / s. This is maintained for 15 minutes to control the melting of the aluminum sheet. At this time, the melting of the aluminum sheet can be seen in the image acquisition device. The aluminum liquid fluctuates and spreads in the evaporation tank.

[0054] S3: When the image acquisition device shows that the aluminum liquid has finished spreading and has stabilized, a pre-evaporation process is performed, controlling the power of the evaporation source to 82% of the total power of the evaporation source (4.92KW). The disappearance of the evaporated aluminum liquid is observed through the viewing window, indicating that this stage is complete.

[0055] S4: After the aluminum liquid evaporates and disappears as observed through the image acquisition device, a slow wire feeding stage begins. At this stage, the wire feeding speed is controlled at V1 = 180 mm / min, and the evaporation source power is controlled to 90% of the total evaporation source power (5.4KW), maintained for 5 minutes. The image acquisition device observes that the liquid surface is spread out, the tungsten mesh is completely wetted by the aluminum liquid without warping, the liquid surface is stable without fluctuations, and the current feedback shows a stable current, indicating the completion of this stage.

[0056] S5: Rapid wire feeding stage. At this stage, the aluminum wire is fed in at a speed of V2 = 400 mm / min, and the evaporation source power is controlled to 91% of the total evaporation source power (5.46KW) and maintained for 5 minutes. The liquid surface is observed to be stable without fluctuation and with a large spreading area through the viewing window, and the current is observed to be stable through current feedback, indicating that this stage is complete.

[0057] S6: Evaporation stage: After the liquid level stabilizes, maintain the wire feeding rate V3 = 400 mm / min as in S5, control the evaporation source power to 88% of the total evaporation source power (5.28KW), and start continuous evaporation deposition on the PET base film.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A vapor deposition method, characterized in that, Includes the following steps: A tungsten mesh is placed in a material trough on the upper surface of an evaporation boat. A solid aluminum source is placed on the tungsten mesh. The evaporation boat, the tungsten mesh, and the solid aluminum source on the tungsten mesh are preheated to remove gas and moisture from the evaporation boat, the tungsten mesh, and the solid aluminum source. The pre-melting process melts the solid aluminum source to form molten aluminum covering part of the tungsten mesh surface; The pre-evaporation treatment causes the molten aluminum to evaporate, forming an initial wetting area; In the first wire feeding stage, aluminum wire is fed in at the first wire feeding rate. The molten aluminum wire spreads in the initial wetting area until the tungsten mesh is completely wetting by the molten aluminum, and the tungsten mesh is at least partially consumed. In the secondary wire feeding stage, aluminum wire is fed in at the second wire feeding rate, and the tungsten mesh is completely consumed. In the vapor deposition stage, an aluminum metal layer is vapor deposited onto the base film.

2. The vapor deposition method according to claim 1, characterized in that, The tungsten mesh is embedded in the bottom of the material trough on the upper surface of the evaporation boat; Preferably, the tungsten mesh has a mesh count of 18-300 meshes per inch and a wire diameter of 0.06 mm-0.2 mm.

3. The vapor deposition method according to claim 1, characterized in that, The volume ratio of the solid aluminum source to the material container on the upper surface of the evaporation boat is 4-6:100; Preferably, the solid aluminum source includes one or both of aluminum sheets and aluminum wires.

4. The vapor deposition method according to claim 1, characterized in that, The first wire feeding rate is less than the second wire feeding rate.

5. The vapor deposition method according to claim 1, characterized in that, During the preheating process, the power of the preheating evaporation source shall not exceed 50% of the total power of the evaporation source. Preferably, the preheating time is 15-25 minutes.

6. The vapor deposition method according to claim 1, characterized in that, During the pre-melting process, the evaporation source power is 65%-75% of the total evaporation source power. Preferably, the pre-melting treatment time is 10-20 min.

7. The vapor deposition method according to claim 1, characterized in that, During the pre-evaporation process, the power of the evaporation source is 80%-85% of the total power of the evaporation source.

8. The vapor deposition method according to claim 4, characterized in that, The vapor deposition method also satisfies at least one of the following conditions: (1) In the first wire feeding stage, the evaporation source power in the first wire feeding stage is 89%-92% of the total evaporation source power; Optionally, the duration of the single wire feeding stage is 3-8 minutes; Optionally, the first wire feeding rate is 150-200 mm / min; (2) In the secondary wire feeding stage, the evaporation source power in the secondary wire feeding stage is 90-92% of the total evaporation source power; Optionally, the duration of the secondary wire feeding stage is 3-8 minutes; Optionally, the second wire feeding rate is 350-450 mm / min.

9. The vapor deposition method according to claim 1, characterized in that, During the vapor deposition stage, the power of the evaporation source is 87%-89% of the total power of the evaporation source.

10. The application of the vapor deposition method according to any one of claims 1-9 in the preparation of composite current collectors.

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