Method for testing water vapor transmittance of adhesive layer

Abstract

The invention relates to the technical field of photovoltaics, and discloses a method for testing the water vapor transmittance of an adhesive layer. The adhesive layer comprises a pressure-sensitive adhesive layer of an aluminum foil tape, the test method comprises the following steps: providing a to-be-tested sample, the to-be-tested sample comprises a first substrate, an adhesive layer and a second substrate which are arranged in a stacked manner, the first substrate is provided with a through hole penetrating through the thickness of the first substrate, the projection of the second substrate is located in the first substrate, and the adhesive layer is formed into an annular structure; the projection of the second substrate is located outside the through hole and located in the second substrate; and arranging the sample to be tested in the water permeability test equipment to obtain the water vapor permeability of the adhesive layer. According to the invention, the effective permeation path of the water vapor in the to-be-tested sample in the adhesive layer is the same as the permeation path of the water vapor of the photovoltaic module in the edge sealing material adhesive layer, that is, the actual water vapor permeation condition of the photovoltaic module is accurately simulated, and the accurate and effective water vapor transmittance of the adhesive layer is obtained; and accurate model selection of the adhesive layer can be realized during preparation of the edge sealing material, and the edge sealing material is applied to scenes with different water blocking requirements and edge sealing requirements.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic technology, and more specifically to a method for testing the water vapor transmission rate of an adhesive layer. Background Technology

[0002] Heterojunction (HJT) modules hold a significant position in the photovoltaic market due to their high efficiency, low temperature coefficient, and bifacial power generation characteristics. A typical HJT module consists of a solar cell layer, upper and lower encapsulating glass layers positioned on the top and bottom sides of the cell layer, and an encapsulating film between the cell layer and the encapsulating glass. Heterojunction cells are extremely sensitive to moisture; moisture penetration can lead to potential-induced degradation (PID) or electrode corrosion. Therefore, the encapsulation process, especially the edge sealing process, is crucial to the long-term reliability of HJT modules. The edge sealing material is typically aluminum foil tape. After the HJT cell layer, encapsulating film, and encapsulating glass are laminated, the aluminum foil tape forms an arc-shaped C-ring around the laminate to block moisture and extend the module's lifespan.

[0003] Aluminum foil tape mainly consists of aluminum foil and an adhesive layer, typically a pressure-sensitive adhesive. The aluminum foil possesses waterproof and moisture-proof properties, enabling the tape to effectively prevent moisture and humidity from penetrating the module. Its high-temperature resistance ensures stability under high-temperature conditions. Combined with a high-quality adhesive layer, it is suitable for bonding with glass to form a reliable seal. However, when moisture does penetrate, water molecules can still seep into the module through the pressure-sensitive adhesive. Since the amorphous silicon layer of heterojunction cells is extremely sensitive to moisture, the water vapor transmission rate (WVTR) of sealing materials such as aluminum foil tape is typically required to be below 1 g / (m²). 2 Especially in high-temperature and high-humidity environments, the moisture permeability requirements for aluminum foil tape are even more stringent. As mentioned above, the barrier performance of sealing materials like aluminum foil tape is currently measured by testing the moisture permeability of the overall structure. For example, several film samples of aluminum foil tape of a certain size are cut and directly laid flat in a test chamber for moisture permeability testing. However, this testing method ignores the precise moisture permeability of the pressure-sensitive adhesive, which directly reflects the moisture permeability performance. This limits the ability to define material boundaries, optimize material selection, and improve economic efficiency.

[0004] Therefore, how to accurately measure the water vapor transmission rate of pressure-sensitive adhesive in aluminum foil tape is a technical problem that the industry urgently needs to solve. Summary of the Invention

[0005] In view of this, the present invention provides a method for testing the water vapor transmission rate of an adhesive layer, in order to solve the problem that the current method for testing the water vapor transmission rate of aluminum foil tape cannot obtain accurate water vapor transmission rate parameters of the pressure-sensitive adhesive layer.

[0006] In a first aspect, the present invention provides a method for testing the water vapor transmission rate of an adhesive layer, the adhesive layer comprising a pressure-sensitive adhesive layer of aluminum foil tape, including:

[0007] A test sample is provided, which includes a first substrate, an adhesive layer and a second substrate stacked together. The first substrate has a through hole that extends through its thickness. The projection of the second substrate is located inside the first substrate. The adhesive layer is formed into an annular structure that adheres to the first substrate and the second substrate. Its projection is located outside the through hole and inside the second substrate.

[0008] The sample to be tested is placed in a water permeability testing device to obtain the water vapor transmission rate of the adhesive layer.

[0009] Beneficial Effects: The water vapor transmission rate testing method for the adhesive layer of the present invention firstly selects a first substrate and a second substrate of different sizes. The larger first substrate forms a through-hole to provide a path for high-humidity water vapor to enter the sample to be tested. The smaller second substrate, at its outer periphery, can form a path with the inner wall of the water transmission test equipment to allow low-humidity water vapor to exit from the sample to be tested. The adhesive layer between the first and second substrates is formed into a ring structure. Water vapor passes through the inner surface of the adhesive layer in a transverse direction until it reaches the outer surface of the adhesive layer. Finally, the outer periphery of the second substrate exits with the inner wall of the water transmission test equipment. In this way, the effective penetration path of water vapor in the adhesive layer in the sample to be tested is the same as the penetration path of water vapor in the edge sealing material adhesive layer of the photovoltaic module. That is, the above-mentioned sample to be tested accurately simulates the actual conditions of water vapor transmission through the adhesive layer of the photovoltaic module, thereby obtaining an accurate and effective water vapor transmission rate of the adhesive layer. This helps to achieve accurate selection of adhesive layers when preparing edge sealing materials, so as to apply to application scenarios with different water resistance requirements and edge sealing requirements, providing optional solutions for industrial optimization and development.

[0010] In one alternative implementation, the sample to be tested is provided, including:

[0011] Provide a second substrate;

[0012] An adhesive layer is coated onto the second substrate to form an adhesive layer;

[0013] The first substrate is covered with an adhesive layer, and the first substrate and the second substrate are pressed together with the adhesive layer.

[0014] Beneficial effects: The second substrate is used as a back plate to support the adhesive layer; after the adhesive layer is coated and formed, the first substrate is used as the front plate to press the adhesive layer, thereby forming a test sample with the first substrate and the second substrate clamping and fixing the adhesive layer. The first substrate with through holes covers the adhesive layer to facilitate positioning and ensures that the surface of the adhesive layer perpendicular to the stacking direction is not exposed, thus ensuring the accuracy of the penetration path.

[0015] In one alternative embodiment, coating an adhesive layer onto the second substrate includes:

[0016] Using a first rotational speed, adhesive is spin-coated onto a portion of the surface of the second substrate;

[0017] The adhesive is homogenized using a second rotation speed to form a uniform adhesive layer of consistent thickness. The first rotation speed is less than the second rotation speed.

[0018] Beneficial Effects: The spin coating process for forming a ring-shaped adhesive layer on a second substrate can be divided into two steps. First, there is a low-speed spreading stage. During this stage, the adhesive is less affected by centrifugal force, resulting in a slow and stable flow. This avoids splashing and removes air bubbles, ensuring uniform adhesive spreading and filling minor unevenness on the second substrate surface, providing a preliminary smooth adhesive layer base. Next, there is a high-speed homogenization stage. High-speed spinning significantly increases centrifugal force, forming a thin and uniform adhesive layer. This enhances the density and mechanical properties of the adhesive layer, improving its abrasion resistance, corrosion resistance, and shear strength. It also helps reduce water absorption, accelerates solvent evaporation, and promotes rapid curing, minimizing performance degradation. In essence, this staged coating process—low-speed spreading followed by high-speed homogenization—achieves initial coverage and defect control, while high-speed homogenization enables precision molding and performance optimization. By controlling the flowability and centrifugal force of the adhesive, the entire process from initial coverage to precision molding is controlled, optimizing the adhesive layer yield.

[0019] In one optional embodiment, the first rotational speed ranges from 500 rpm to 1000 rpm, the second rotational speed ranges from 1000 rpm to 2000 rpm, the time for spin-coating the adhesive on a portion of the second substrate ranges from 10 s to 20 s, and the time for homogenizing the adhesive ranges from 30 s to 60 s.

[0020] Beneficial effects: By controlling the rotation speed and process time, precise shaping control of the adhesive layer can be achieved.

[0021] In one optional embodiment, before providing the second substrate, the method further includes: pre-treating the first substrate and the second substrate, including: performing plasma treatment on the first substrate and the second substrate; cleaning the first substrate and the second substrate, wherein the cleaning agent includes one or more of propanol, isopropanol, and deionized water; and drying the first substrate and the second substrate with nitrogen gas.

[0022] Beneficial effects: Plasma treatment is performed on the surfaces of the first and second substrates to improve the adhesion between the surfaces of the first and second substrates, facilitating reliable bonding and fixation with the adhesive layer; then, various cleaning reagents are used for cleaning to remove impurities generated during plasma treatment and reduce surface damage; finally, nitrogen gas is used for drying to ensure the dryness of the first and second substrates.

[0023] In one alternative embodiment, the first substrate, the adhesive layer, and the second substrate are concentrically disposed.

[0024] Beneficial effects: Concentric setup facilitates precise positioning of the various structures and helps obtain accurate morphological parameter data for each structure. Furthermore, under concentric setup, the three components can be of the same shape or different shapes, improving the adaptability of the test sample while simplifying processing and assembly.

[0025] In one optional embodiment, both the first substrate and the second substrate are circular plates with circular holes and an adhesive layer that is annular. The radius of the first substrate is set to R1, the radius of the through hole is set to R2, the radius of the second substrate is set to R3, the inner diameter of the adhesive layer is set to R4 and the outer diameter is set to R5. The dimensions of the adhesive layer are set with the following relationship: R4≥R2 and R5≤R3.

[0026] Beneficial effects: The circular structure is easy to form and has high adaptability; the adhesive layer is located in at least the area where the second substrate and the first substrate overlap, so that the upper and lower surfaces of the adhesive layer are fully attached to the first substrate and the second substrate, and then the inner and outer walls of the ring are exposed, ensuring the accuracy of the effective transverse penetration area.

[0027] In one optional embodiment, the radius R1 of the first substrate is greater than the inner diameter of the chamber of the water penetration test device; the radius R2 of the through hole is in the range of 0 < R2 ≤ 2.5 cm; the radius R3 of the second substrate is in the range of R2 < R3 ≤ 4 cm; and the thickness D of the adhesive layer is in the range of 30 μm ≤ D ≤ 55 μm.

[0028] Beneficial effects: The radius R1 of the first substrate is equal to the inner diameter of the chamber of the water penetration testing equipment to ensure the airtight seal between the sample to be tested and the inner wall of the equipment. Selecting the parameters of each layer within the above range helps to achieve precise and controllable structural forming and analysis.

[0029] In one optional implementation, the water penetration testing device includes:

[0030] The enclosure includes a first portion and a second portion arranged opposite to each other. The first portion has a hollow low-humidity chamber, and the second portion has a hollow high-humidity chamber.

[0031] An installation platform is located at one end of the first section facing the second section. The installation platform has an opening that connects the high humidity chamber and the low humidity chamber. The installation platform is used to fix the edge of the sample to be tested so that the sample to be tested closes the opening and relatively seals the high humidity chamber and the low humidity chamber.

[0032] The first inlet and the first outlet are located on the housing and are suitable for connecting the high humidity chamber with the external environment; the first inlet is suitable for the input of high humidity media and the first outlet is suitable for the output of high humidity media.

[0033] The second inlet and the second outlet are located on the housing and are suitable for connecting the low-humidity chamber with the external environment; the second inlet is suitable for inputting the drying medium and the second outlet is suitable for outputting the low-humidity medium.

[0034] A water vapor detection structure is installed at the second outlet to obtain the water vapor concentration in the low humidity chamber.

[0035] Beneficial effects: The enclosure can be divided into two parts, a first section and a second section, arranged vertically. The upper second section has a high-humidity chamber for introducing a high-humidity medium, while the lower first section serves as a low-humidity chamber, with the two sections connected vertically. During installation, the upper second section is opened, and the sample to be tested is horizontally placed on the mounting platform at the top of the second section. The first substrate of the sample is tightly fixed to the mounting platform at its edges using sealant or a sealing ring. The entire sample is placed in the opening of the mounting platform, thus completely sealing the low-humidity chamber. Then, the second section is pressed tightly against the first section to form a sealed high-humidity chamber, minimizing or even preventing moisture penetration at the connection between the first substrate and the inner wall, ensuring sealing performance. During water vapor transmission testing, the high-humidity chamber can achieve 100% relative humidity using a water vapor generator or a saturated salt solution, meaning the water vapor content in the high-humidity chamber reaches saturation. The water vapor concentration in the high-humidity chamber is maintained by continuously supplying humidifying nitrogen gas through the first inlet, while the second outlet remains open, ensuring a stable and uniform high-humidity medium. The low-humidity chamber maintains 0% relative humidity by continuously supplying dry carrier gas (such as nitrogen) through the first inlet and keeping the second outlet open. The water vapor detection structure can be an infrared sensor, which uses an infrared water vapor transmission tester to detect the absorption characteristics of water vapor at specific infrared wavelengths, accurately measuring the water vapor transmission rate (WVTR) of the adhesive layer in the test.

[0036] In one optional embodiment, the method of obtaining the water vapor transmission rate of the adhesive layer by placing the sample to be tested in a water permeability testing device includes:

[0037] The sample to be tested is placed between the high humidity chamber and the low humidity chamber of the water permeability testing equipment;

[0038] After a preset time, the theoretical water vapor transmission rate and theoretical water permeability area displayed by the water permeability testing equipment are read. The theoretical water permeability area is the horizontal cross-sectional area of ​​the inner cavity of the water permeability testing equipment.

[0039] Calculate the actual water permeable area of ​​the adhesive layer based on its inner diameter and thickness;

[0040] Based on the theoretical water vapor transmission rate, theoretical water permeable area, and actual water permeable area, the actual water vapor transmission rate of the adhesive layer is calculated.

[0041] Beneficial effect: By replacing the theoretical value obtained from the water permeability tester, the accurate water vapor transmission rate of the adhesive layer in the sample to be tested can be obtained. Attached Figure Description

[0042] 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.

[0043] Figure 1 This is a schematic diagram of a photovoltaic module using aluminum foil tape for edge sealing in related technologies;

[0044] Figure 2 This is a schematic flowchart of the water vapor transmission rate test method for the adhesive layer according to an embodiment of the present invention;

[0045] Figure 3 This is a front view schematic diagram of the sample preparation structure according to an embodiment of the present invention;

[0046] Figure 4 This is a top view schematic diagram of the sample preparation structure according to an embodiment of the present invention;

[0047] Figure 5 This is a schematic diagram of the structure of the water penetration testing device according to an embodiment of the present invention.

[0048] Explanation of reference numerals in the attached figures:

[0049] 1. Battery cell layer; 2. Upper encapsulation glass; 3. Lower encapsulation glass; 4. Encapsulation film; 5. Aluminum foil tape; 51. Aluminum foil; 52. Adhesive layer;

[0050] 10. Sample to be tested; 101. First substrate; 1011. Through hole; 102. Adhesive layer; 103. Second substrate;

[0051] 20. Water penetration test equipment; 201. Chamber; 202. High humidity chamber; 203. Low humidity chamber; 204. Mounting platform; 205. First inlet; 206. First outlet; 207. Second inlet; 208. Second outlet. Detailed Implementation

[0052] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It is understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. It should also be noted that, for ease of description, only the parts relevant to the invention are shown in the drawings, not all structures. In the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily obscuring the concept of the invention. Various structural schematic diagrams according to embodiments of the present invention are shown in the drawings. These figures are not drawn to scale, and some details are enlarged for clarity, and some details may be omitted. The shapes of the various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from actual practices due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed. In the context of the present invention, when a layer / element is referred to as being "on" another layer / element, the layer / element may be directly on the other layer / element, or there may be an intermediate layer / element between them. Additionally, if one layer / component is "above" another layer / component in one orientation, then when the orientation is reversed, that layer / component can be "below" that other layer / component.

[0053] In the solar energy field, photovoltaic (PV) modules typically consist of a photovoltaic laminate, an outer frame, and a circuit component, which includes parts such as junction boxes. (See reference...) Figure 1 A photovoltaic (PV) laminate typically includes a solar cell layer 1, an upper encapsulation glass 2 and a lower encapsulation glass 3 located on the upper and lower sides of the solar cell layer 1 respectively, an encapsulation film 4 located between the encapsulation glass and the solar cell layer 1, and an outer frame surrounding the PV laminate. Because the solar cell layer 1 is sensitive to moisture, an edge-sealing material, such as aluminum foil tape, is usually applied to the periphery of the PV laminate. The aluminum foil tape includes waterproof aluminum foil and an adhesive layer 52, which includes materials such as pressure-sensitive adhesive. After the aluminum foil tape is adhered to the PV laminate, moisture molecules may still travel along the edge of the module during long-term use. Figure 1 The arrow indicates that the material penetrates laterally into the adhesive layer 52, thus affecting the performance of the battery cell layer 1. Currently, the barrier performance of sealing materials such as aluminum foil tape 5 is often measured by testing the water vapor transmission rate of the overall structure. This testing method ignores the precise water vapor transmission rate of the adhesive layer 52, which directly reflects the water vapor permeability performance, thus limiting its effectiveness in defining material boundaries, optimizing material selection, and improving economic efficiency.

[0054] Therefore, this embodiment provides a method for testing the water vapor transmission rate of the adhesive layer 102, enabling accurate water vapor transmission rate testing of the pressure-sensitive adhesive in the aluminum foil tape 5, and also providing an example of accurate water vapor detection for various edge sealing materials or sealing materials with adhesive layer 52, thereby improving the efficiency of product development and material selection.

[0055] Based on this, see Figures 2 to 4 This embodiment provides a method for testing the water vapor transmission rate of an adhesive layer 102, wherein the adhesive layer 102 includes a pressure-sensitive adhesive layer 52 of an aluminum foil tape 5. Figure 2 The following is a flowchart illustrating the testing method, which includes the following steps:

[0056] Step S201: Provide a test sample 10. The test sample 10 includes a first substrate 101, an adhesive layer 102, and a second substrate 103 stacked together. The first substrate 101 has a through hole 1011 extending through its thickness. The projection of the second substrate 103 is located inside the first substrate 101. The adhesive layer 102 is formed into an annular structure that adheres to the first substrate 101 and the second substrate 103. Its projection is located outside the through hole 1011 and inside the second substrate 103.

[0057] For example, the materials of the first substrate 101 and the second substrate 103 mentioned above can be one of metal plates such as glass, aluminum plate, steel plate, copper plate, and organic plates such as acrylic plate, which have strict water-blocking performance and weather resistance; the adhesive layer 102 includes pressure-sensitive adhesive, which can be a solvent-based pressure-sensitive adhesive, preferably a solvent-based acrylic pressure-sensitive adhesive, which has the characteristics of high initial tack, fast drying speed, good water resistance and strong adhesion to the substrate.

[0058] The adhesive layer 102 is sandwiched between a first substrate 101 and a second substrate 103. The two substrates have relative sizes, with the larger first substrate 101 forming a through-hole 1011. The area where the through-hole 1011 is located provides a path area for water vapor to flow toward the adhesive layer 102. (Reference) Figure 3 As indicated by the vertical arrow in the middle; the smaller second substrate 103, on the one hand, can receive the adhesive layer 102, and on the other hand, cuts off the continued flow of water vapor flowing downward from the through hole 1011 and the space within the inner diameter of the adhesive layer 102, so that the downward water vapor can flow horizontally towards the adhesive layer 102 on the periphery after reaching the surface of the second substrate 103, as shown in the figure. Figure 3As indicated by the horizontal arrow, the test sample 10 formed by sandwiching the adhesive layer 102 between the first substrate 101 and the second substrate 103 provides test conditions for water vapor to pass laterally through the adhesive layer 102. Such test conditions are consistent with the situation when the photovoltaic laminate is sealed with edge sealing material, and external environmental water vapor enters the interior of the photovoltaic laminate from the adhesive layer 52. The water vapor enters the adhesive layer 102 laterally. On the other hand, the smaller second substrate 103 has a gap between its outer periphery and the outer periphery of the first substrate 101. When the test sample 10 is installed in the chamber of the water penetration test equipment 20, a gap space is formed between the outer periphery of the second substrate 103 and the inner wall of the chamber. In this way, water vapor passing horizontally through the adhesive layer 102 can flow out away from the adhesive layer 102 in this gap space. That is, the second substrate 103, whose projected area is smaller than that of the first substrate 101, can form a path for penetrating the adhesive layer 102 and flowing out on one side of its outer periphery with the inner wall of the water penetration test equipment 20, providing conditions for achieving accurate water penetration testing.

[0059] Step S201: The sample to be tested 10 is placed in the water permeability testing device 20 to obtain the water vapor transmission rate of the adhesive layer 102.

[0060] The sample 10 to be tested is placed in the water vapor transmission test device 20 to perform a water vapor transmission test. The water vapor transmission test device 20 can be a water vapor translucency meter or similar structure. The path of water vapor penetrating the adhesive layer 102 in the sample 10 simulates the path of water vapor in the external environment penetrating the adhesive layer 52 of the sealing material in the photovoltaic module. The water vapor transmission test device 20 is used to simulate water transmission conditions and obtain specific test parameters, and finally the accurate water vapor transmission rate of the adhesive layer 102 of the sample 10 is obtained.

[0061] In summary, the above-mentioned method for testing the water vapor transmission rate of the adhesive layer 102 firstly selects a first substrate 101 and a second substrate 103 of different sizes. The larger first substrate 101 forms a through hole 1011 to provide a path for high-humidity water vapor to enter the sample 10 to be tested. The smaller second substrate 103 can form a path with the inner wall of the water transmission test device 20 at its outer periphery to allow low-humidity water vapor to be output from the sample 10 to be tested. The adhesive layer 102 disposed between the first substrate 101 and the second substrate 103 is formed into a ring structure. Water vapor passes through the inner surface of the adhesive layer 102 in the transverse direction until it reaches the outer surface of the adhesive layer 102. Finally, the water vapor is output from the outer periphery of the second substrate 103 and the inner wall surface of the water transmission test device 20. Thus, the effective permeation path of water vapor in the adhesive layer 102 of the test sample 10 is the same as the permeation path of water vapor in the edge sealing material adhesive layer 52 of the photovoltaic module. That is, the test sample 10 accurately simulates the actual conditions of water vapor permeating the adhesive layer 52 of the photovoltaic module, thereby obtaining an accurate and effective water vapor permeability of the adhesive layer 102. This helps to achieve accurate selection of the adhesive layer 102 when preparing the edge sealing material, so as to apply it to application scenarios with different water resistance and edge sealing requirements, and provide optional solutions for the optimized development of the industry.

[0062] In one embodiment, reference Figure 3 The above-mentioned step S201 of providing the sample to be tested 10 includes:

[0063] Step S2011: Provide a second substrate 103;

[0064] Step S2012: An adhesive layer 102 is formed by coating the second substrate 103.

[0065] In step S2013, the first substrate 101 is covered with the adhesive layer 102, and the first substrate 101 and the second substrate 103 are pressed together with the adhesive layer 102.

[0066] refer to Figure 3 and Figure 4 That is, the second substrate 103 is used as the back plate to support the adhesive layer 52; after the adhesive layer 102 is coated and formed, the first substrate 101 is used as the front plate to press the adhesive layer 102, thereby forming a test sample 10 in which the first substrate 101 and the second substrate 103 clamp and fix the adhesive layer 102. The first substrate 101 with through holes 1011 covers the adhesive layer 102 to facilitate positioning, ensuring that the surface of the adhesive layer 102 perpendicular to the stacking direction is not exposed, and ensuring the accuracy of the penetration path.

[0067] In one embodiment, step S2012 of coating the adhesive layer 102 on the second substrate 103 includes:

[0068] Using a first rotational speed, an adhesive is spin-coated onto a portion of the surface of the second substrate 103.

[0069] The adhesive is homogenized using a second rotation speed to form an adhesive layer 102 of uniform thickness throughout; the first rotation speed is less than the second rotation speed.

[0070] That is, the spin coating process is used to form a ring-shaped adhesive layer 102 on the second substrate 103. This can be done in two steps. The first step is a low-speed spreading stage. When rotating at low speed, the adhesive is less affected by centrifugal force and flows slowly and steadily, which can avoid adhesive splashing and eliminate air bubbles, ensuring the uniformity of adhesive spreading. At the same time, it can also fill the tiny unevenness on the surface of the second substrate 103, providing a preliminary flat adhesive layer 52 base. The next step is a high-speed homogenization stage. Through high-speed rotation and homogenization, the centrifugal force is significantly increased, and the adhesive forms a thin and uniform adhesive layer 102. This helps to enhance the density and mechanical properties of the adhesive layer 102, improve the wear resistance, corrosion resistance and shear strength of the adhesive layer 102, and also helps to reduce water absorption, accelerate the evaporation of solvent in the adhesive, achieve rapid curing and reduce performance degradation. This is a staged adhesive coating process that first spreads the adhesive at a low speed and then spreads it at a high speed. The low-speed spreading achieves initial coverage and defect control, while the high-speed spreading achieves precision molding and performance optimization. By controlling the flowability and centrifugal force of the adhesive, the entire process from initial coverage to precision molding is achieved, thus optimizing the yield of the adhesive layer 102.

[0071] In one optional embodiment, the first rotational speed of the low-speed spreading stage ranges from 500 rpm to 1000 rpm, and the second rotational speed of the high-speed spin coating stage ranges from 1000 rpm to 2000 rpm. The time range for spin coating the adhesive onto a portion of the surface of the second substrate 103, i.e., the low-speed spreading stage, is 10 s to 20 s, and the time range for homogenizing the adhesive, i.e., the high-speed spin coating stage, is 30 s to 60 s. By controlling the rotational speed and process time, precise shaping control of the adhesive layer 102 is achieved.

[0072] In one embodiment, before step S2011 of providing the second substrate 103, the method further includes: pre-treating the first substrate 101 and the second substrate 103, including: performing plasma treatment on the first substrate 101 and the second substrate 103; cleaning the first substrate 101 and the second substrate 103, wherein the cleaning agent includes one or more of propanol, isopropanol, and deionized water; and drying the first substrate 101 and the second substrate 103 with nitrogen gas.

[0073] Plasma treatment is performed on the surfaces of the first substrate 101 and the second substrate 103 to improve the adhesion of the surfaces of the first substrate 101 and the second substrate 103, so as to facilitate reliable bonding and fixation with the adhesive layer 102; then, various cleaning reagents are used for cleaning to remove impurities generated by plasma treatment and reduce surface damage; finally, nitrogen gas is blown dry to ensure the dryness of the first substrate 101 and the second substrate 103.

[0074] In one embodiment, the first substrate 101, adhesive layer 102, and second substrate 103 are concentrically arranged. This concentricity includes the inner and outer diameters of the first substrate 101, the through-hole 1011, the adhesive layer 102, and the second substrate 103. This concentric arrangement facilitates precise positioning of the various structures and helps obtain accurate morphological parameter data for each structure. Furthermore, given this concentric arrangement, the three components can have the same shape or different shapes. For example, the first substrate 101 can be adapted to the internal cavity shape of the water penetration testing equipment 20, and the second substrate 103 can be circular, square, or other shapes, improving the adaptability of the sample 10 under test while simplifying processing and assembly.

[0075] In one optional embodiment, both the first substrate 101 and the second substrate 103 are circular plates, the through hole 1011 is a circular hole, and the adhesive layer 102 is annular. The circular structures are concentrically arranged, resulting in a circular structure that is easy to mold and highly adaptable. Based on this, refer to... Figure 4 The radius of the first substrate 101 is set to R1, the radius of the through hole 1011 is set to R2, the radius of the second substrate 103 is set to R3, the inner diameter of the adhesive layer 102 is set to R4 and the outer diameter is set to R5. Then the size setting of the adhesive layer 102 has the following relationship: R4≥R2 and R5≤R3.

[0076] That is, the radius R1 of the first substrate 101, the radius R2 of the through hole 1011, and the radius R3 of the second substrate 103 have the following relationship: R2 < R3 ≤ R1. Based on this, the adhesive layer 102 is located in at least the area where the second substrate 103 overlaps with the first substrate 101, so that the upper and lower surfaces of the adhesive layer 102 are fully attached to the first substrate 101 and the second substrate 103. Then the annular inner wall and outer wall are exposed to ensure the accuracy of the effective transverse penetration area.

[0077] In one embodiment, the radius R1 of the first substrate 101 is greater than the inner diameter of the chamber of the water penetration testing device 20 to ensure that the sample to be tested 10 can be snapped into the water penetration testing device 20 and that the sealing between the sample and the inner wall of the water penetration testing device 20 is good. For example, the radius R1 of the first substrate 101 can be 5 cm.

[0078] The radius R2 of the aforementioned through hole 1011 is in the range of 0 < R2 ≤ 2.5 cm, preferably in the range of 0.5 cm to 1 cm, such as 0.5 cm, 0.6 cm, 0.7 cm, 0.8 cm, 0.9 cm, and 1 cm. The radius R3 of the second substrate 103 is in the range of R2 < R3 ≤ 4 cm. That is, when the radius of the through hole 1011 is selected between 0.5 cm and 1 cm, the radius R3 of the second substrate 103 can be in the range of 0.5 cm to 4 cm, preferably 2 cm to 2.5 cm, such as 2 cm, 2.1 cm, 2.2 cm, 2.3 cm, 2.4 cm, and 2.5 cm.

[0079] In the aforementioned test sample 10, a water vapor permeation test is allowed for an adhesive layer 102 with a thickness of 0–1 mm. When the adhesive layer 102 is used for edge sealing of a heterojunction component, the thickness D of the pressure-sensitive adhesive layer 102 is in the range of 30 μm ≤ D ≤ 55 μm, for example, it can be 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, etc.

[0080] refer to Figure 5 The aforementioned water permeability testing device 20 includes: a housing 201, a mounting platform 204, a water vapor detection structure, and multiple connecting ports formed on the housing 201. The housing 201 includes a first section and a second section arranged opposite to each other. The first section has a hollow low-humidity chamber 203, and the second section has a hollow high-humidity chamber 202. The mounting platform 204 is located at one end of the first section facing the second section. The mounting platform 204 has an opening connecting the high-humidity chamber 202 and the low-humidity chamber 203. The mounting platform 204 is used to fix the edge of the sample to be tested 10 so that the sample to be tested 10 closes the opening. The connecting ports include a first inlet 205 and a first outlet 206 located on the housing 201, and a second inlet 205. The inlet 207 and outlet 208, the first inlet 205 and the first outlet 206 are adapted to connect the high humidity chamber 202 with the external environment, the first inlet 205 is adapted to input high humidity medium, and the first outlet 206 is adapted to output high humidity medium; the second inlet 207 and the second outlet 208 are adapted to connect the low humidity chamber 203 with the external environment, the second inlet 207 is adapted to input dry medium, and the second outlet 208 is adapted to output low humidity medium; the water vapor detection structure is set at the second outlet 208 to obtain the water vapor concentration in the low humidity chamber 203.

[0081] Specifically, the housing 201 can be divided into two movable upper and lower parts. The upper second part has a high humidity chamber 202 suitable for introducing a high humidity medium, and the lower first part has a low humidity chamber 203. The upper end of the lower first part is provided with an installation platform 204 with an opening. The installation platform 204 is fixed to the edge of the sample to be tested 10 so that the sample to be tested 10 seals the opening. During installation, open the upper second section, then clean the surface of the mounting platform 204 and the sample 10 to be tested, ensuring that there is no dust or oil. Then, place the sample 10 to be tested flat on the mounting platform 204. Next, apply sealant or sealing rings evenly along the edge of the sample 10 to form a continuous sealing ring between it and the mounting platform 204, avoiding blockage of the breathable area. The sealant can be a special sealant, including high vacuum grease, solvent-free sealing wax (such as beeswax + rosin mixture), and silicone-based sealant. Then, apply pressure to make the sample 10 to be tested adhere tightly to the mounting platform 204. After the sealing material cures, seal the lower low humidity chamber 203. Finally, press the second section firmly on top of the first section to form a sealed high humidity chamber 202 on top. The process of fixing the sample to be tested 10 specifically involves fixing the outer periphery of the first substrate 101 onto the mounting platform 204. The mounting platform 204 can be a snap-fit ​​platform formed at the upper end of the first section, or a clamp set at the upper end of the first section. This ensures that the outer periphery of the first substrate 101 is tightly fitted to the inner wall of the chamber, minimizing or even avoiding water vapor penetration at the connection between the first substrate 101 and the inner wall, thus ensuring sealing performance. During the water penetration test, the high humidity chamber 202 can achieve a relative humidity of 100% through a water vapor generator or a saturated salt solution, meaning that the water vapor content in the high humidity chamber 202 reaches the saturated water vapor content. Furthermore, the water vapor concentration in the high humidity chamber 202 is maintained by continuously introducing humidifying nitrogen gas from the first inlet 205, while keeping the second outlet 208 open, ensuring that the high humidity medium in the high humidity chamber 202 is stable and uniform. The low humidity chamber 203, on the other hand, maintains a low humidity of 0% by continuously introducing dry carrier gas (such as nitrogen) through the first inlet 205 and keeping the second opening open. The water vapor detection structure can be an infrared sensor, that is, by using an infrared water vapor transmission tester to detect the absorption characteristics of water vapor at a specific infrared wavelength, the water vapor transmission rate (WVTR) of the adhesive layer 102 in the test is accurately measured. It is known that the water vapor testing equipment also includes a temperature and humidity control module, which controls the environment inside the chamber through heating / cooling components; and a data interface that displays real-time temperature, humidity, and transmittance curves.

[0082] The principle of infrared spectroscopy for detecting water vapor transmittance is as follows: First, water vapor molecules have specific absorption wavelengths in the infrared spectrum, especially strong absorption peaks near the near-infrared wavelength of 2.6 μm and the mid-infrared wavelength of 6.3 μm. When infrared light passes through a carrier gas containing water vapor molecules, the intensity of these wavelengths is attenuated due to absorption by the water vapor molecules. Then, by measuring the change in absorbance, the water vapor concentration can be calculated, and the transmittance can be derived.

[0083] The relationship between absorbance A1 and water vapor concentration is: A1 = ε·l·c. Where ε is the molar absorptivity of water vapor molecules at a specific wavelength; l is the optical path length, that is, the path length of infrared light through the gas; and c is the water vapor concentration.

[0084] The formula for calculating water vapor transmission rate is: Where C is the water vapor concentration (g / m³) measured in the low-humidity chamber 203. 3 F is the carrier gas velocity (m). 3 / day); A2 is the effective test area (m²) 2 ).

[0085] The above two formulas are the principle formulas used in the water permeability testing equipment 20 to test the water vapor transmission rate of the film. However, due to the setting problem of the water permeability tester, the effective test area is usually assumed to be the inner diameter of the chamber of the water vapor testing equipment. Therefore, in order to obtain the accurate water vapor transmission rate of the adhesive layer 102 in the sample to be tested 10, it is usually necessary to perform a conversion.

[0086] That is, step S202, which involves placing the sample to be tested 10 in the water vapor transmission testing device 20 to obtain the water vapor transmission rate of the adhesive layer 102, includes:

[0087] Step S2021: The sample to be tested 10 is placed between the high humidity chamber 202 and the low humidity chamber 203 of the water penetration test device 20.

[0088] refer to Figure 5 The sample preparation 10 divides the chamber of the water penetration testing device 20 into a relatively sealed high-humidity chamber 202 and a low-humidity chamber 203. The testing requirements for the high-humidity chamber 202 and the low-humidity chamber 203 are then maintained, meaning the relative humidity of the high-humidity chamber 202 is ensured to be 100%, and the relative humidity of the low-humidity chamber 203 is ensured to be 1%. Furthermore, the temperature of the chambers is ensured to be between 30 and 90°C to maintain the water vapor state.

[0089] Step S2022: After a preset time, read the theoretical water vapor transmission rate and theoretical water permeability area displayed by the water permeability testing device 20. The theoretical water permeability area is the horizontal cross-sectional area of ​​the inner cavity of the water permeability testing device 20.

[0090] The preset duration can be 24 hours, but for efficiency reasons, it is actually possible to select 5 to 6 hours to read the theoretical water vapor transmission rate. The corresponding theoretical water-permeable area at this time is the default effective test area of ​​the water-permeability testing equipment 20, which is the area of ​​the horizontal cross-section of the inner cavity of the chamber, and can be expressed as... Where R0 is the inner diameter of the cavity.

[0091] Step S2023: Calculate the actual water permeable area of ​​the adhesive layer 102 based on its outer diameter and thickness.

[0092] The actual water-permeable area of ​​the adhesive layer 102 is the inner ring area of ​​the annular adhesive layer 102, which can be expressed as A. 实际 =2πR4·D, where R4 is the inner diameter of the adhesive layer 102 and D is the thickness of the adhesive layer 102.

[0093] Step S2024: Calculate the actual water vapor transmission rate of the adhesive layer 102 based on the obtained theoretical water vapor transmission rate, theoretical water permeable area, and actual water permeable area.

[0094] That is, according to The theoretical water vapor transmission rate (WVTR) and theoretical water permeable area (A0) are read from the known water permeability testing equipment 20, and then combined with the calculated actual water permeable area (A). 实际 The actual and accurate water vapor permeability of the adhesive layer 102 can be obtained by conversion.

[0095] Further functional descriptions of the above structures are the same as those of the corresponding embodiments described above, and will not be repeated here.

[0096] The above description does not provide detailed explanations of the technical aspects of each layer's patterning, etching, etc. However, those skilled in the art should understand that various technical means can be used to form layers and regions of the desired shape. Furthermore, to form the same structure, those skilled in the art can also design methods that are not entirely identical to those described above. Additionally, although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination.

[0097] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A method for testing the water vapor transmission rate of an adhesive layer, wherein the adhesive layer comprises a pressure-sensitive adhesive layer of aluminum foil tape, characterized in that, include: A test sample is provided, the test sample includes a first substrate, an adhesive layer and a second substrate stacked together, the first substrate has a through hole that extends through its thickness, the projection of the second substrate is located inside the first substrate, and the adhesive layer is formed into an annular structure that is bonded between the first substrate and the second substrate, the projection of which is located outside the through hole and inside the second substrate. The sample to be tested is placed in a water permeability testing device to obtain the water vapor transmission rate of the adhesive layer.

2. The method for testing the water vapor transmission rate of the adhesive layer according to claim 1, characterized in that, The provision of the sample to be tested includes: Provide a second substrate; An adhesive layer is coated onto the second substrate to form an adhesive layer; The first substrate is covered by the adhesive layer, and the first substrate and the second substrate are pressed together to press the adhesive layer.

3. The method for testing the water vapor transmission rate of the adhesive layer according to claim 2, characterized in that, The process of coating an adhesive layer on the second substrate includes: Using a first rotational speed, a spin coat of adhesive is applied to a portion of the surface of the second substrate; The adhesive is homogenized using a second rotation speed to form an adhesive layer of uniform thickness throughout; the first rotation speed is less than the second rotation speed.

4. The method for testing the water vapor transmission rate of the adhesive layer according to claim 3, characterized in that, The first rotational speed ranges from 500 rpm to 1000 rpm, and the second rotational speed ranges from 1000 rpm to 2000 rpm. The time range for spin-coating the adhesive onto a portion of the surface of the second substrate is 10s to 20s, and the time range for homogenizing the adhesive is 30s to 60s.

5. The method for testing the water vapor transmission rate of the adhesive layer according to claim 2, characterized in that, Prior to providing the second substrate, the method further includes: The pretreatment of the first substrate and the second substrate includes: plasma treatment of the first substrate and the second substrate; cleaning the first substrate and the second substrate with a cleaning agent including one or more of propanol, isopropanol, and deionized water; and drying the first substrate and the second substrate with nitrogen gas.

6. The method for testing the water vapor transmission rate of the adhesive layer according to claim 1, characterized in that, The first substrate, the adhesive layer, and the second substrate are arranged concentrically.

7. The method for testing the water vapor transmission rate of the adhesive layer according to claim 6, characterized in that, Both the first substrate and the second substrate are circular plates, the through hole is a circular hole, and the adhesive layer is annular; the radius of the first substrate is set to R1, the radius of the through hole is set to R2, the radius of the second substrate is set to R3, the inner diameter of the adhesive layer is set to R4 and the outer diameter is set to R5, and the size settings of the adhesive layer have the following relationship: R4≥R2 and R5≤R3.

8. The method for testing the water vapor transmission rate of the adhesive layer according to claim 7, characterized in that, The radius R1 of the first substrate is greater than the inner diameter of the chamber of the water penetration test device; the radius R2 of the through hole is in the range of 0 < R2 ≤ 2.5 cm; the radius R3 of the second substrate is in the range of R2 < R3 ≤ 4 cm; the thickness D of the adhesive layer is in the range of 30 μm ≤ D ≤ 55 μm.

9. The method for testing the water vapor transmission rate of the adhesive layer according to claim 1, characterized in that, The water penetration testing equipment includes: The enclosure includes a first portion and a second portion arranged opposite to each other, the first portion having a hollow low-humidity chamber and the second portion having a hollow high-humidity chamber; An installation platform is located at one end of the first section facing the second section. The installation platform has an opening that connects the high humidity chamber and the low humidity chamber. The installation platform is used to fix the edge of the sample to be tested so that the sample to be tested closes the opening and relatively seals the high humidity chamber and the low humidity chamber. A first inlet and a first outlet are located on the housing and are adapted to connect the high humidity chamber with the external environment; the first inlet is adapted for input of high humidity media and the first outlet is adapted for output of high humidity media. A second inlet and a second outlet are located on the housing and are adapted to connect the low-humidity chamber with the external environment; the second inlet is adapted for input of the drying medium and the second outlet is adapted for output of the low-humidity medium. A water vapor detection structure is installed at the second outlet to obtain the water vapor concentration in the low humidity chamber.

10. The method for testing the water vapor transmission rate of the adhesive layer according to any one of claims 1-9, characterized in that, The step of setting the sample to be tested in a water permeability testing device to obtain the water vapor transmission rate of the adhesive layer includes: The sample to be tested is placed between the high humidity chamber and the low humidity chamber of the water permeability testing equipment; After a preset time, the theoretical water vapor transmission rate and theoretical water permeability area displayed by the water permeability testing device are read. The theoretical water permeability area is the horizontal cross-sectional area of ​​the inner cavity of the water permeability testing device. Calculate the actual water permeable area of ​​the adhesive layer based on its inner diameter and thickness; The actual water vapor transmission rate of the adhesive layer is calculated based on the theoretical water vapor transmission rate, the theoretical water permeable area, and the actual water permeable area.

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