Evaporation coating method

Abstract

The application discloses an evaporation coating method, comprising the following steps: S1, inputting a base film to be coated into a vacuum chamber, and arranging an evaporation boat in the vacuum chamber corresponding to the base film; S2, providing a pre-melting area corresponding to a wire feeding position, the pre-melting area has a temperature higher than a melting temperature of a metal wire, and the pre-melting area has a space for pre-melting and heating of metal melting products, so as to sufficiently heat and melt the metal melting products; and S3, electrifying the evaporation boat to perform evaporation coating. In the evaporation coating process, the metal wire melting products are controlled to enter the space in the pre-melting area, and the metal particles are sufficiently heated and melted in the flowing process in the space, so that splashing of the particles in the subsequent metal solution evaporation process is reduced.

Description

Technical Field

[0001] This invention relates to the field of current collector technology, and more particularly to an evaporation coating method. Background Technology

[0002] The most common method for uniformly coating metals, especially aluminum, is high-vacuum belt evaporation. The process involves bringing an aluminum wire close to an evaporation boat, where the wire melts and sublimates into aluminum vapor. The substrate to be coated is then passed over the evaporation boat, and the aluminum vapor is deposited as a thin metallic layer on the substrate surface.

[0003] Current vapor deposition methods generally employ evaporators (evaporation boats) using either a drum-type or suspended design. During the vapor deposition process, the surface temperature of the evaporation boat reaches the vaporization temperature of the molten metal under a certain vacuum, thus evaporating the metal. However, due to the fixed wire feeding point, the metal wire melts at a fixed position on the boat and diffuses to both sides of the boat. Since there is less molten aluminum on both sides along the length of the boat, the temperature of the unwetted parts of the boat is relatively higher, which may cause the molten aluminum to boil violently during the wetting and diffusion process.

[0004] In the prior art, to address the above problems, several grooves / holes are set on the surface of the boat to improve the wettability of the boat surface and the dispersion of the molten metal in order to fully spread the molten aluminum, such as Chinese patent CN216141608U, thereby improving the problem of aluminum sputtering; there are also methods to control the resistance of each area of ​​the evaporation boat to maintain the stability of the evaporation boat current, so that the surface temperature of the evaporation boat is uniform, thereby improving the uniformity of the coating, such as CN219280011U.

[0005] Considering the process of aluminum wire undergoing evaporation coating, from solid to liquid on the evaporation boat, and then thermally diffused from liquid to gas, spatter occurs when fine solid aluminum particles or impurity particles are impacted by high-temperature steam. In existing technologies, during the melting process of the metal wire, a small amount of unmelted metal particles or impurities remain in the molten material. Simultaneously, these particles diffuse with the molten liquid to the high-temperature zone of the boat, where gas molecules generated during evaporation impact these particles, causing aluminum sputtering and affecting the porosity. Therefore, further improvements are needed. Summary of the Invention

[0006] This invention aims to at least partially solve one of the technical problems in the related art. To this end, one object of this invention is to provide an evaporation coating method that, during wire feeding, extends the preheating and melting time of the molten metal wire at a temperature lower than that of its surrounding environment, thereby improving the porosity of the evaporated film.

[0007] The technical solution of the present invention is as follows:

[0008] An evaporation coating method includes the following steps:

[0009] S1 inputs the base film to be coated into the vacuum chamber, and an evaporation boat is set up in the vacuum chamber corresponding to the base film;

[0010] S2 provides a pre-melting zone corresponding to the wire feeding point, which has a temperature above the melting temperature of the metal wire, and the pre-melting zone has space for pre-melting and heating of the molten metal to fully heat and melt the molten metal;

[0011] S3 powers the evaporation boat to perform vapor deposition.

[0012] Furthermore, a movement path for the molten metal is provided on the pre-melting zone, and part of the movement path is located in the heating space inside the pre-melting zone.

[0013] Furthermore, the total length of the moving path is greater than the straight-line distance between the liquid inlet port of the moving path and the surface of the evaporation boat.

[0014] Furthermore, the temperature of the pre-melting zone increases from top to bottom.

[0015] Furthermore, the temperature of the pre-melting zone is not higher than the evaporation temperature of the molten metal in the vacuum environment.

[0016] Furthermore, the pre-melting zone is equipped with a space for temporary storage and residence of the molten material.

[0017] Furthermore, the space is a buffer zone connected to the movement path. The buffer zone deviates from the movement trajectory of the movement path, thereby creating an accumulation zone of molten material in the buffer zone, allowing a small amount of particulate matter to remain and be heated and melted.

[0018] Furthermore, the pre-melting zone is a raised island structure set on the evaporation surface of the evaporation boat corresponding to the wire feeding point.

[0019] Furthermore, the pre-melting zone is designed as a frustum or column shape.

[0020] Furthermore, the pre-melting zone includes a liquid inlet side corresponding to the wire feeding point, and the liquid inlet port of the moving path is located on the liquid inlet side;

[0021] In addition, the drain port of the moving path is located on the drain side near the evaporation surface.

[0022] Furthermore, the center lines of the inlet of the liquid inlet path and the center line of the outlet of the liquid outlet path do not coincide with the central axis of the buffer zone.

[0023] Furthermore, a compensation zone is set at the bottom of the evaporation boat corresponding to the pre-melting zone to increase the temperature at the bottom of the pre-melting zone.

[0024] Furthermore, the compensation zone is a section with a cross-sectional area protruding from the bottom of the hull.

[0025] The beneficial effects of this invention are as follows: Based on the vapor deposition method of this invention, by controlling the molten metal wire to enter the space within the pre-melting zone during the vapor deposition process, and fully heating and melting the metal particles during the flow in the space, the splashing of the particles during the subsequent evaporation of the metal solution is reduced. Attached Figure Description

[0026] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0027] Figure 1 This is a flowchart of the vapor deposition method of the present invention;

[0028] Figure 2 This is a schematic diagram of the evaporation coating method proposed in this invention;

[0029] Figure 3 for Figure 2 A schematic diagram of the cross-sectional structure;

[0030] Figure 4 This is a schematic diagram of the cross-sectional structure of the second type of pre-melting zone;

[0031] Figure 5 This is a schematic diagram of the cross-sectional structure of the third type of pre-melting zone;

[0032] Figure 6 This is a schematic diagram of the cross-sectional structure of the fourth type of premelting zone;

[0033] Figure 7 This is a schematic diagram of the cross-sectional structure of the fifth type of pre-melting zone.

[0034] In the figure: 1-Boat; 11-First surface; 12-Second surface; 13-Evaporation surface; 14-Compensation zone; 2-Pre-melting zone; 21-Liquid inlet side; 211-Liquid inlet path; 212-Buffer zone; 22-Liquid outlet side; 221-Liquid outlet path.

[0035] x represents the length direction; z represents the thickness direction. Detailed Implementation

[0036] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0037] Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the invention, and should not be construed as limiting the invention.

[0038] Reference Figure 1 An evaporation coating method includes the following steps:

[0039] S1 inputs the base film to be coated into the vacuum chamber, and an evaporation boat is set up in the vacuum chamber corresponding to the base film;

[0040] like Figure 2 As shown, the evaporation boat includes a boat body 1, with a first surface 11 and a second surface 12 at both ends of the boat body 1 for contacting and being clamped and fixed with electrodes; the evaporation side of the boat body 1 is provided with an evaporation surface 13 for carrying and heating the evaporating molten metal. Figure 1 The paper only shows a planar boat structure for the evaporation surface 13. In the prior art, slotted evaporation boats or other irregularly shaped evaporation boats should also be included within the scope of protection of this application.

[0041] S2 provides a pre-melting zone 2 corresponding to the wire feeding point, which has a temperature above the melting temperature of the metal wire, and the pre-melting zone has space for pre-melting and heating of the molten metal to fully heat and melt the molten metal;

[0042] S3 powers the evaporation boat to perform vapor deposition. This type of evaporation boat is installed in the same way as a conventional evaporation boat, clamped inside the electrodes, and an appropriate voltage is set according to the material to be deposited.

[0043] The implementation method of the evaporation boat structure is as follows:

[0044] Example 1

[0045] Further reference Figure 2 and Figure 3 The pre-melting zone 2 is configured as a trapezoidal island-shaped protrusion with a path for the molten metal to move. A liquid inlet side 21 is provided corresponding to the wire feeding point, with the liquid inlet port of the moving path located on the liquid inlet side 21. A liquid outlet side 22 is located near the evaporation surface, with the liquid outlet port of the moving path located on the liquid outlet side 22. This island-shaped protrusion can be directly die-cast together with the boat body (using the same material as the boat body), or it can be subsequently press-fitted to the boat body (with corresponding locking slots on the boat body). Similarly, the path within it can be directly molded, or holes can be opened later. The pre-melting zone as a whole can also be configured in other shapes, such as a cylinder, elliptical cylinder, or rectangle.

[0046] The moving path includes an inlet path 211 corresponding to the inlet side 21, with the centerline of the inlet path 211 pointing vertically downwards and perpendicular to the surface of the boat hull 1. Simultaneously, the moving path also includes a drain path 221 corresponding to the drain side 22, which is connected to the inlet path 221. In this embodiment, each drain side 22 is provided with a drain path. The actual path can be selected according to requirements. In principle, a drain path is provided along the length of the boat hull to facilitate the spreading of molten metal. However, the required amount of molten metal is relatively small along the width of the boat hull, so no path or a path with a smaller diameter may be provided. The design selection is based on the pre-melting zone and the size of the boat hull.

[0047] The aforementioned liquid inlet path 211 and liquid outlet path 221 are paths located inside the pre-melting zone 2. Of course, the path where the molten metal wire drips onto the surface of the liquid inlet side 21 and overflows towards the liquid inlet path 211 should also be considered a moving path (the liquid inlet side 21 is preferably recessed to facilitate the flow of molten metal). Similarly, the path where the molten metal discharged from the liquid outlet path 221 slides down the wall along the liquid outlet side 22 is also a moving path. Clearly, the total length of the moving paths is greater than the straight-line distance between the liquid inlet port of the moving path and the surface of the evaporation boat. The liquid outlet path 221 is inclined towards the surface of the boat, with an inclination angle not exceeding 10°.

[0048] Since the pre-melting zone 2 protrudes from the surface of the boat body, is far from the heat source, and increases the cross-sectional area of ​​the boat body, reducing the resistance, its overall temperature will be lower than the surface temperature of the boat body, and the temperature increases from top to bottom. The temperature of the pre-melting zone is preferably not higher than the evaporation temperature of the molten metal in the vacuum environment. On the one hand, this avoids boiling over in the pre-melting zone, and on the other hand, it helps to control the magnitude of the voltage applied to the boat body, which has a smaller impact on the relevant parameters in the vapor deposition process, and thus will not have a significant impact on the equipment.

[0049] A prominent pre-melting zone is provided, along with a built-in path channel for the flow of molten metal. This reduces the exposure of molten metal to the outside to a certain extent, preventing unmelted particles or impurities in the molten metal from flowing directly onto the surface of the boat and reducing the probability of splashing. In this embodiment, the inlet path 211 is configured with a hole structure with decreasing aperture. The vapor-deposited molten metal flows down the side wall of the inlet path 211 to the inlet of the outlet path 221, and then flows from the side wall of the outlet path 221 to the evaporation surface of the boat 1. During this process, the molten material is continuously heated, allowing the incompletely melted metal particles to be fully melted.

[0050] In this implementation, the diameter of the liquid inlet path is set in a decreasing manner, while the diameter of the liquid outlet path is set in an increasing manner.

[0051] Example 2

[0052] Further reference Figure 4To further reduce the impact of particulate matter on the vapor deposition process, a space for temporary storage and residence of molten material is provided in the pre-melting zone. Specifically, in this embodiment, a recessed buffer zone 212 is set at the end of the liquid inlet path 211. The depth of the buffer zone 212 is deeper than that of the inlet end of the liquid outlet path 221, thereby creating a molten material accumulation zone in the buffer zone 212. At the same time, the buffer zone 212 is close to the surface of the boat and has a relatively higher temperature, which can promote the melting of unmelted aluminum particles. The buffer zone 212 provides a residence space for particulate matter, and since the density of particulate matter is generally greater than that of molten liquid, particulate matter is more likely to accumulate in the buffer zone and is not easily discharged directly to the surface of the boat, thereby reducing the impact of the particulate matter on the entire molten system.

[0053] Meanwhile, a compensation zone 14 is set at the bottom of the boat hull corresponding to the pre-melting zone 2. It is a block with an increased cross-sectional area, which reduces the local resistance (impedance) to a certain extent, increases the temperature at that location (especially the temperature at the bottom of the pre-melting zone), and further increases the heating temperature of the buffer zone 212.

[0054] Example 3

[0055] Reference Figure 5 The difference between this embodiment and Embodiment 2 is that the liquid inlet path 211 is designed with a continuously bent path structure, and its inlet (partially) is offset from the bottom buffer zone 212, that is, the centerline does not coincide with the central axis of the buffer zone; thus, the upper path forms a barrier, which can reduce the splashing of molten material near the surface of the boat from the holes, and also increases the heating movement path to a certain extent, which can fully preheat the molten material and melt a small amount of unmelted metal particles. In this example, the diameter of the liquid inlet path is uniform.

[0056] In addition, the liquid inlet path 211 can also be set as a spiral (not shown); or it can be a path structure with increasing pore size (not shown), which increases the internal volume and is beneficial for the dispersion of the melt.

[0057] Example 4

[0058] Reference Figure 6 The difference between this embodiment and embodiment three is that a horizontal groove is also formed on the side wall of the liquid inlet path 211, which serves as a buffer zone 212 for the flow of the molten material; similarly, it also provides a temporary storage space for the flowing molten material.

[0059] In addition, other buffer structures that communicate with the sidewalls of the inlet path 211 and / or outlet path 221 should also be covered within the scope of protection of this application.

[0060] Example 5

[0061] Reference Figure 7The difference between this and Example 3 is that the bottom sidewall of the drain path 221 forms a bowl-shaped cavity structure for temporarily storing the molten material, which serves as a buffer zone 212. It forms a certain angle α with the horizontal plane, preferably not exceeding 5°, to avoid accumulating too much molten metal and affecting the temperature uniformity of the boat. It can also work in conjunction with the groove-shaped buffer zone formed at the bottom.

[0062] Hole Data Detection

[0063] Further vapor deposition is performed, and the number of pores in the vapor-deposited film is detected using CCD vision.

[0064] Comparative Example 1: A conventional evaporation boat structure was selected, with dimensions of 130*35*10 mm (tank depth 5 mm, tank length 100 mm). The evaporation voltage was controlled at 9.6V and dynamically adjusted based on the evaporation boat's illumination status. The vacuum level was controlled at 10... -2 For MBA and above, 6μm PET film is selected as the film material, and the evaporation is carried out in 2 passes. The evaporation is performed with the wire feeding speed controlled at 300mm / min. The diameter of the aluminum wire is 1.8mm.

[0065] In Comparative Example 2, only a conical boss with a diameter of 6 / 10 mm (both large and small diameters) and a height of 7 mm is set as a support platform for the molten aluminum.

[0066] An evaporation boat with the pre-melting zone path structure of Examples 1 to 5 was selected. The pre-melting zone was a conical boss with a diameter of 6 / 10 mm and a height of 7 mm. A conical hole was obtained by directly machining it with a conical drill bit. The large hole diameter was 4 mm and the small hole diameter was 2 mm. The bending path was obtained by die casting and its diameter was 2 mm. In Example 4, the buffer zone thickness of the internal path was 0.5 mm and the depth was 1 mm, and 6 sets were set. In the above examples, the inclination of the bottom (upward or downward) of the drain path was 3°. The width of the bottom buffer zone was 2 mm and the depth was 1.2 mm. The other parameters were the same as those in Comparative Example 1.

[0067]

[0068]

[0069] As can be seen from the above data, directly setting the boss as the carrier and pre-melting zone of the molten material can preheat the molten material of the metal wire to a certain extent. Therefore, the boiling situation caused by the temperature difference of the solution is improved and the overall porosity is improved to a certain extent. However, there are still cases where unmelted metal particles flow into the surface of the boat along with the solution.

[0070] Based on the technical solution in this application, it can be seen that by setting a pre-melting space inside the pre-melting zone, the part of the flow path that passes through the high temperature is much larger than the external flow, resulting in a better pre-melting effect. When it flows into the surface of the evaporation boat, it has little impact on the temperature of the molten metal spread on the surface of the boat, and the metal particles have basically melted, thus reducing the number of large-diameter holes.

[0071] Further setting up a pre-melting zone can further increase the residence time of the molten material and provide storage space for particulate matter, reducing the overflow of unmelted particles or impurities onto the evaporation surface of the boat, thus further improving the porosity level; at the same time, the temporary storage zone being off-center from the centerline and off-center from the liquid inlet path can also improve the aluminum splashing caused by internal boiling phenomena.

[0072] In this application, the structures and connections not described in detail are all prior art, and their structures and principles are well known, so they will not be described in detail here.

[0073] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," or "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0074] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0075] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An evaporation coating method, characterized in that, Includes the following steps: S1 Inputs the base film to be coated into the vacuum chamber, and an evaporation boat is set up in the vacuum chamber corresponding to the base film; S2 provides a pre-melting zone corresponding to the wire feeding point, which has a temperature above the melting temperature of the metal wire, and the pre-melting zone has space for pre-melting and heating of the molten metal to fully heat and melt the molten metal; S3 energizes the evaporation boat to perform vapor deposition; The temperature of the pre-melting zone increases from top to bottom in the thickness direction; and the temperature of the pre-melting zone is not higher than the evaporation temperature of the molten metal in the vacuum environment; a movement path for the molten metal is provided on the pre-melting zone, part of which is located in the heating space inside the pre-melting zone, and the flow path of the molten metal in the preheating zone is carried out entirely in a vertical inclined channel, while the temperature of the pre-melting zone is set from low to high in the vertical direction.

2. The evaporation coating method as described in claim 1, characterized in that, The total length of the moving path is greater than the straight-line distance between the liquid inlet port of the moving path and the surface of the evaporation boat.

3. The evaporation coating method as described in claim 2, characterized in that, The pre-melting zone has a space for temporary storage and residence of the molten material.

4. The evaporation coating method as described in claim 3, characterized in that, The space is a buffer zone connected to the movement path. The buffer zone deviates from the trajectory of the movement path, thereby creating an area where molten material can accumulate.

5. The evaporation coating method as described in claim 4, characterized in that, The pre-melting zone is a raised island structure set on the evaporation surface of the evaporation boat corresponding to the wire feeding point.

6. The evaporation coating method as described in claim 5, characterized in that, The pre-melting zone includes the liquid inlet side set at the corresponding wire feeding point, and the liquid inlet port of the moving path is set at the liquid inlet side; In addition, the drain port of the moving path is located on the drain side near the evaporation surface.

7. The evaporation coating method as described in claim 5 or 6, characterized in that, The centerlines of the inlet of the liquid inlet path and the centerline of the outlet of the liquid outlet path do not coincide with the central axis of the buffer zone.

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