Composite board structure bonded with thermosetting adhesive

Abstract

The utility model discloses a kind of composite board structures bonded with thermosetting back adhesive, and the composite board structure bonded with thermosetting back adhesive includes film, thermosetting back adhesive and carrier plate matrix. Thermosetting back adhesive, one side is arranged on the bottom surface of the film, and the thermosetting back adhesive is pressed to the film by a hot-pressing equipment with 50~60 degrees Celsius, 1~3Bar pressure and 5~20 seconds. Carrier plate matrix, the other side of the thermosetting back adhesive is arranged on the top, and the film and the thermosetting back adhesive are positioned and placed to the carrier plate matrix, and the thermosetting back adhesive reaches the preset adhesive strength by the hot-pressing equipment with 75~110 degrees Celsius, 2~5Bar pressure and 10~480 seconds, so that the film and the carrier plate matrix are integrated products after completing gluing.

Description

Technical Field

[0001] This utility model relates to a composite board structure, specifically a composite board structure bonded with thermosetting adhesive that can be used in a paid transaction anti-tampering device. It is suitable for bonding flexible printed circuit boards to carrier substrates, or other composite material bonding scenarios that require high strength and precise positioning. Background Technology

[0002] In existing bonding technologies for composite board structures, instant adhesives, pressure-sensitive adhesives, or hot melt adhesives with a single temperature range are commonly used. These technologies have several drawbacks: instant adhesives have insufficient bonding strength and are prone to detachment after long-term use; pressure-sensitive adhesives have poor temperature resistance and are prone to failure in high-temperature environments; and hot melt adhesives with a single temperature range can easily damage the film (such as the circuit pattern on a flexible printed circuit board) if the temperature is too high, while the adhesion is not strong if the temperature is too low.

[0003] In the field of composite material bonding, especially in the integration of functional films and carrier substrates, the appropriateness of the bonding technology directly affects the product yield, reliability, and service life. Currently, the mainstream bonding solutions in the industry are mainly divided into three categories, but each has its own insurmountable drawbacks:

[0004] (a) Limitations of traditional adhesive materials

[0005] Instant adhesives (cyanoacrylates): They bond quickly, but the adhesive layer is brittle and prone to cracking due to temperature changes and vibrations during long-term use, leading to detachment. They have poor compatibility with dissimilar materials such as plastics and ceramics, and the bonding strength is usually only 5~8 N / cm. Furthermore, they have a narrow temperature range (-10~60℃), making them unsuitable for high-temperature working environments.

[0006] Pressure-sensitive adhesive (PSA): It has good initial tack and adhesion, but its temperature resistance and durability are insufficient. It is prone to softening and glue overflow in environments above 60°C. The adhesive strength decreases significantly over time, and the peel strength decreases by more than 50% after long-term use, making it difficult to meet the service life requirements of electronic products of up to 5 to 10 years.

[0007] Single-temperature stage hot melt adhesive: If high temperature (above 120℃) curing is used, it is easy to damage the printed circuit pattern of flexible printed circuit board (FPC) (especially precision circuit with line width ≤0.1mm), resulting in open circuit or short circuit; if low temperature (below 50℃) curing is used, the adhesive cannot fully melt and cross-link, resulting in insufficient bonding strength, and extremely poor adhesion to carrier substrates with low surface energy such as ceramics.

[0008] (II) Core defects of traditional manufacturing processes

[0009] Insufficient positioning accuracy: Traditional processes often use a three-layer hot-pressing method of directly stacking "film-adhesive-carrier". The adhesive is prone to flow at high temperatures, causing the film to shift relative to the carrier substrate. The positioning error is usually between 0.5 and 1 mm, which cannot meet the requirement of ≤0.1 mm for the alignment of precision electronic components (such as FPC with sensors and chips).

[0010] Poor material compatibility: Most adhesives can only be matched with a single type of carrier substrate. For example, adhesives designed for plastic substrates are prone to "false adhesion" on ceramic substrates, with peel strength below 3 N / cm, making it difficult to meet the application requirements of multi-material carriers.

[0011] Conflicting process parameters: Traditional processes cannot meet the dual requirements of "protecting the film" and "ensuring adhesion strength". Either the film is damaged due to high temperature, or the adhesion is not strong due to low temperature. The product yield is usually less than 85%.

[0012] (III) Market Demand and Technology Gap

[0013] As electronic products become increasingly thinner, more precise, and more reliable, the requirements for composite board structures are becoming increasingly stringent: they not only need an adhesive strength of ≥15N / cm and a positioning error of ≤0.1mm, but also need to be compatible with various carrier materials such as plastics and ceramics, and maintain stable performance over a wide temperature range of -40~120℃. Existing technologies cannot simultaneously meet these requirements; therefore, there is a strong need for a composite board structure that combines low-temperature protection, high-strength adhesion, precise positioning, and wide compatibility. Utility Model Content

[0014] The core objective of this invention is to overcome the numerous shortcomings of existing technologies and provide a composite board structure bonded with thermosetting adhesive, primarily for use in payment transaction anti-tampering devices, specifically achieving the following objectives:

[0015] 1. Achieve staged temperature control: low-temperature protection film during the pre-pressing stage (especially for precision circuit patterns), and appropriate temperature curing during the final bonding stage to ensure bonding strength, avoiding the "temperature contradiction" of traditional technologies.

[0016] 2. Improve positioning accuracy and control the relative offset error between the film and the substrate to within 0.1mm to meet the assembly requirements of precision electronic components.

[0017] 3. Enhance the stability and durability of the adhesive structure, ensuring an adhesive strength of ≥15N / cm, with no delamination or adhesive overflow within a wide temperature range of -40~120℃, and a service life of more than 8 years.

[0018] 4. Compatible with plastics (ABS, PC, PPS, PC / ABS, etc.), ceramics (alumina, aluminum nitride, etc.), and various carrier substrate materials, expanding the application scenarios of the technology.

[0019] 5. Optimize the process flow and simplify the operation steps to increase the product yield to over 95%.

[0020] To achieve the above objectives, this utility model provides a composite board structure bonded with thermosetting adhesive for use in a payment transaction anti-tampering device. The composite board structure bonded with thermosetting adhesive includes a film, thermosetting adhesive, and a carrier substrate. The thickness of the film ranges from 0.05 to 0.2 millimeters (mm). This film serves as the anti-tampering functional bearing layer and signal transmission medium. One side of the thermosetting adhesive is disposed on the bottom surface of the film. The thermosetting adhesive is pressed onto the film using a hot press at 50-60 degrees Celsius, a pressure of 1-3 Bar, and a time of 5-20 seconds, wherein the thickness of the thermosetting adhesive ranges from 0.03 to 0.15 mm. The top of the carrier substrate is located on the other side of the thermosetting adhesive. The film and the thermosetting adhesive that have been pressed together are positioned on the carrier substrate and then subjected to a hot press at 75-110 degrees Celsius and 2-5 Bar for 10-480 seconds to make the thermosetting adhesive reach the preset bonding strength, so that the film and the carrier substrate are bonded together to form a finished product.

[0021] In one embodiment of this utility model, the film is provided with an anti-tampering functional unit, which is an integrally formed conductive line or conductive coating, and is signal-connected to the control unit of the payment transaction anti-tampering device. The control unit activates the anti-tampering protection measures in real time.

[0022] In one embodiment of this utility model, the film is a flexible printed circuit (FPC) film, and the film has a printed circuit pattern.

[0023] In one embodiment of this utility model, the material of the carrier substrate is a plastic substrate or a ceramic material.

[0024] In one embodiment of this utility model, during the pre-pressing bonding stage, one side of the thermosetting adhesive is aligned and laid on the bottom surface of the film by manual or automated equipment to ensure that the deviation between the edge of the thermosetting adhesive and the edge of the film is ≤0.2mm.

[0025] In summary, the composite board structure bonded with thermosetting adhesive provided by this utility model can bring the following benefits:

[0026] 1. Balance between temperature and protection: The low temperature design of 50~60℃ in the pre-compression stage perfectly matches the temperature resistance limit of precision films such as FPC, avoiding damage to circuit patterns and solving the core defects of traditional high-temperature curing; the appropriate temperature curing of 75~110℃ in the final bonding stage ensures that the thermosetting adhesive is fully cross-linked, and the bonding strength reaches 15~25N / cm, which is 2~3 times that of traditional instant adhesives and pressure-sensitive adhesives.

[0027] 2. Significantly improved positioning accuracy: The design of "pre-compression and fixation followed by positioning" avoids the offset caused by the flow of colloid. Combined with the vision positioning system and high-precision positioning structure, the positioning error is controlled within 0.1mm, which is far better than the error range of 0.5~1mm of traditional technology, and fully meets the assembly requirements of precision electronic components.

[0028] 3. Wide material compatibility: The thermosetting adhesive formula is matched with the surface treatment of the carrier substrate. The adhesion strength to plastic substrates such as ABS, PC, and PC / ABS is ≥15N / cm, and the adhesion strength to ceramic substrates such as alumina and aluminum nitride is ≥18N / cm, which solves the problem of poor compatibility of traditional adhesive materials with heterogeneous substrates.

[0029] 4. Excellent durability and environmental adaptability: The cured adhesive layer has excellent temperature resistance, humidity resistance and aging resistance. The adhesive strength decreases by ≤10% in a wide temperature range of -40~120℃. After 1000 hours of high temperature and high humidity test (85℃, 85%RH), there is no delamination or glue overflow. The service life is more than 8 years, meeting the long-term reliability requirements of the electronics, automotive and other fields.

[0030] 5. Simplified process and improved yield: The phased process flow is clear and can be integrated with automated production lines to reduce human error; the product yield has been increased from below 85% in traditional technology to over 95%, production efficiency has been increased by 30%, and manufacturing costs have been reduced.

[0031] 6. Expanded application scenarios: It is not only suitable for bonding FPC to substrates, but can also be extended to composite structures of other functional films (such as optical films and waterproof films) and different substrates, covering multiple fields such as electronics, automobiles, industrial control, and consumer electronics, with broad application prospects.

[0032] The following detailed description through specific embodiments will make it easier to understand the purpose, technical content, features and effects achieved by this utility model. Attached Figure Description

[0033] Figure 1A This is a schematic diagram of the composite board structure of this utility model, which is bonded with thermosetting adhesive.

[0034] Figure 1BThis is a schematic diagram of the composite board structure bonded with thermosetting adhesive for use as a payment transaction anti-tampering device according to this utility model.

[0035] Figure 2 This is a flowchart of the thermosetting adhesive backing process for the composite board structure of this utility model.

[0036] Figure 3 This is another flowchart of the thermosetting adhesive backing process for the composite board structure of this utility model.

[0037] Explanation of reference numerals in the attached figures: 100 - Composite board structure bonded with thermosetting adhesive; 110 - Film; 112 - Anti-tampering functional unit; 120 - Thermosetting adhesive; 130 - Carrier substrate; 200, 400 - Thermosetting adhesive process method for combined composite board structure; 300 - Payment transaction anti-tampering device; S210, S220, S230, S240 - Steps; S410, S420, S430, S440 - Steps. Detailed Implementation

[0038] Please see Figure 1A and Figure 1B , Figure 1A This is a schematic diagram of the composite board structure of this utility model, which is bonded with thermosetting adhesive. Figure 1BThis is a schematic diagram of a composite board structure bonded with thermosetting adhesive for use in a payment transaction anti-tampering device according to this utility model. The composite board structure 100 bonded with thermosetting adhesive is mainly used in the payment transaction anti-tampering device 300, as shown in the following embodiment (III), corresponding to payment transaction scenarios such as self-service payment terminals, parking lot charging equipment, and electronic payment terminals. The core requirement is to have a highly reliable anti-tampering function. As shown in the figure, the composite board structure 100 bonded with thermosetting adhesive includes a film 110, a thermosetting adhesive 120, and a carrier substrate 130. The thickness of the film 110 ranges from 0.05 to 0.2 millimeters (mm), and the film 110 serves as the anti-tampering function bearing layer and signal transmission medium. The thermosetting adhesive 120 is disposed on the bottom surface of the film 110. In a pre-press bonding stage, the thermosetting adhesive 120 is pressed onto the film 110 by a hot press under operating conditions of 50 to 60 degrees Celsius, 1 to 3 Bar, and 5 to 20 seconds. In the pre-pressing bonding stage, the pressure is controlled at 1-3 standard atmospheres (bar), and the reaction time is 5-20 seconds. The thickness of the thermosetting adhesive 120 ranges from 0.03 to 0.15 mm. A carrier substrate 130 is positioned on the other side of the thermosetting adhesive 120. In a part positioning stage, the already pressed film 110 and the thermosetting adhesive 120 are positioned on the carrier substrate 130. Then, in a final bonding stage, the thermosetting adhesive 120 is brought to a preset bonding strength using a hot press under operating conditions of 75-110 degrees Celsius, 2-5 bar, and 10-480 seconds, allowing the film 110 and the carrier substrate 130 to be bonded together as a single finished product. In this final bonding stage, the pressure is controlled at 2-5 standard atmospheres (bar), and the reaction time is 10-480 seconds.

[0039] Furthermore, the film 110 is provided with an anti-tampering functional unit 112, which is an integrally formed conductive line or conductive coating, and is signal-connected to the control unit (not shown) of the payment transaction anti-tampering device 300. The control unit activates the anti-tampering protection measures in real time. The film 110 is a flexible printed circuit board (FPC) film, and has a printed circuit pattern. The substrate 130 is made of plastic or ceramic material.

[0040] Please refer to Figures 1A to 2 , Figure 2This is a flowchart of the thermosetting adhesive process for the composite panel structure of this utility model. The thermosetting adhesive process 200 for the composite panel structure, mainly applicable to the paid transaction anti-tampering device 300, involves one side of a thermosetting adhesive disposed on the bottom surface of the film, and the top of a carrier substrate disposed on the other side of the thermosetting adhesive. The thermosetting adhesive process method 200 for composite board structures may include, but is not limited to, the following steps: in a pre-pressing bonding stage, a thermosetting adhesive is pressed onto a film using a hot press under operating conditions of 50-60 degrees Celsius, 1-3 Bar pressure, and 5-20 seconds (step S210); in a part positioning stage, the pressed film and the thermosetting adhesive are positioned and placed on the carrier substrate (step S220); in a final bonding stage, the thermosetting adhesive is made to reach a preset bonding strength using the hot press under operating conditions of 75-110 degrees Celsius, 2-5 Bar pressure, and 10-480 seconds (step S230); and the film and the carrier substrate are then bonded together to form a finished product (step S240).

[0041] In addition, another set of examples with parameter ranges (temperature, pressure, and time) is provided; please refer to them. Figure 3 , Figure 3 This is another flowchart of the thermosetting adhesive process for the composite panel structure of this utility model. The thermosetting adhesive process 400 for the composite panel structure can be used in a paid transaction anti-tampering device. One side of the thermosetting adhesive is disposed on the bottom surface of the film, and the top of a carrier substrate is disposed on the other side of the thermosetting adhesive. The thickness of the film ranges from 0.05 to 0.2 mm, and the thickness of the thermosetting adhesive ranges from 0.03 to 0.15 mm. The film serves as the anti-tampering functional bearing layer and signal transmission medium. The thermosetting adhesive process for the composite panel structure may include the following steps, but is not limited thereto: In a pre-pressing bonding stage, at a temperature of... A thermosetting adhesive is pressed onto a film using a hot press at 95-120 degrees Celsius, 2-6 Bar pressure, and 3-10 seconds (step S410); in a part positioning stage, the pressed film and the thermosetting adhesive are positioned and placed on the carrier substrate (step S420); in a final bonding stage, the thermosetting adhesive is made to reach a preset bonding strength using the hot press at 120-250 degrees Celsius, 5-30 Bar pressure, and 5-180 seconds (step S430); and the film and the carrier substrate are bonded together to form a finished product (step S440).

[0042] The following will further explain the relevant details of the composite board structure of this utility model that is bonded with thermosetting adhesive.

[0043] The technical solution of this utility model includes a "composite board structure 100 bonded with thermosetting adhesive". Its core design is to achieve the above-mentioned utility model objective by using a phased process of "pre-pressing bonding - component positioning - final bonding" in combination with thermosetting adhesive with specific parameters and equipment parameters.

[0044] (a) Composite board structure bonded with thermosetting adhesive 100

[0045] The composite board structure 100, which is bonded with thermosetting adhesive, is an integrated structure with three layers stacked together. From top to bottom, it consists of a film 110, a thermosetting adhesive 120, and a carrier substrate 130. The technical parameters and connection relationships of each component are as follows.

[0046] The core function of film 110 is to provide a functional surface layer (such as circuit transmission, signal sensing, etc.), or to serve as an anti-tampering protective layer or a decorative layer. The material selection for film 110 is preferably flexible printed circuit board (FPC) film, but it can also be functional films such as polyimide (PI) film, polyethylene terephthalate (PET) film, and polycarbonate (PC) film. Specific parameters of film 110 include a thickness range of 0.05~0.2mm (with FPC film thickness preferably 0.08~0.12mm), and the surface can be printed with circuit patterns (line width 0.05~0.4mm, line spacing 0.05~0.4mm) as required. Positioning holes (diameter 0.5~2mm) are provided on the edges for precise positioning during the manufacturing process. Performance requirements for film 110 include a temperature resistance range ≥120℃ and a tensile strength ≥50MPa, ensuring no deformation or damage during hot pressing.

[0047] The core function of thermosetting adhesive 120 is to achieve high-strength and durable bonding between film 110 and carrier substrate 130, combining the temporary fixation in the pre-compression stage with the permanent curing characteristics in the final stage.

[0048] Material selection for thermosetting adhesive 120: Preferably epoxy resin thermosetting adhesive, polyurethane thermosetting adhesive, or epoxy-phenolic resin composite thermosetting adhesive (selected according to the substrate material: polyurethane is preferred for plastic substrates, and epoxy-phenolic composite is preferred for ceramic substrates). Specific parameters of thermosetting adhesive 120: Thickness 0.03~0.15mm (ensuring uniform adhesive layer without air bubbles), initial melting point 50~60℃ (matching the pre-pressing stage temperature), complete curing temperature 75~110℃ (matching the final bonding stage temperature), Shore hardness D 60~80 after curing, dielectric strength ≥20kV / mm (suitable for insulation requirements in the electronic field). Connection relationship of thermosetting adhesive 120: One side is tightly bonded to the bottom surface (non-functional surface) of film 110, and the other side is tightly bonded to the top surface of substrate 130. Molecular-level bonding is achieved through staged hot pressing, with no gaps and no excess adhesive.

[0049] The core function of the carrier substrate 130 is to provide the supporting strength and installation foundation for the composite board structure, adapting to the environmental requirements of different application scenarios. Material selection for the carrier substrate 130: plastic substrates (ABS, PC, PPS, PA66, PC / ABS, etc., suitable for lightweight and impact-resistant applications) or ceramic materials (alumina, aluminum nitride, zirconium oxide, etc., suitable for high-temperature, high-insulation, and high-precision applications). Specific parameters of the carrier substrate 130: thickness 0.8~5mm, dimensions set according to application requirements (commonly 50mm×50mm~300mm×300mm), top surface with positioning structures (positioning pins, positioning grooves, or vacuum adsorption areas), positioning structure accuracy error ≤0.05mm, ensuring alignment accuracy with the film 110. Surface treatment of the carrier substrate 130: the top surface of the ceramic substrate can be sandblasted (roughness Ra 0.4~1.2μm), and the top surface of the plastic substrate can be textured (VDI 15~21) to improve adhesion with the thermosetting adhesive 120.

[0050] Correspondence of key process parameters

[0051] Pre-pressing bonding stage: temperature 50~60℃ (below the temperature resistance critical value of film 110, above the initial melting point of thermosetting adhesive 120), pressure 1~3 standard atmospheres (bar) (to ensure that thermosetting adhesive 120 is in close contact with film 110 without damaging film 110), reaction time 5~20 seconds (to allow thermosetting adhesive 120 to soften initially and fix to film 110 without flowing).

[0052] Final bonding stage: temperature 75~110℃ (to fully cross-link and cure the thermosetting adhesive 120), pressure 2~5 standard atmospheres (bar) (higher than the pre-pressure stage, to ensure tight bonding between the thermosetting adhesive 120 and the carrier substrate 130), reaction time 10~480 seconds (adjusted according to the thickness of the thermosetting adhesive 120 and the material of the carrier substrate: the thicker the thermosetting adhesive 120, the longer the time required for the ceramic substrate).

[0053] (II) Manufacturing process of thermosetting adhesive backing for composite panel structures 200

[0054] This process method 200 is designed based on the aforementioned composite plate structure 100, and achieves precise and high-strength bonding between the film 110 and the carrier substrate 130 through four consecutive steps. The specific steps are as follows:

[0055] Pre-compression bonding stage (step S210)

[0056] Preparatory steps: Place the film 110 and thermosetting adhesive 120 in a clean environment (Class 1000 cleanroom, temperature 20~25℃, humidity 40%~60%) and let them stand for 2 hours to remove surface dust and moisture; check whether the functional surfaces of the film 110 (such as the circuit pattern of the FPC) are intact and whether there are bubbles or impurities in the thermosetting adhesive 120.

[0057] Laying and alignment: The thermosetting adhesive 120 is laid on the bottom surface of the film 110 by manual or automated equipment, aligning one side with the film 120, ensuring that the deviation between the edge of the thermosetting adhesive 120 and the edge of the film 110 is ≤0.2mm, without any offset or wrinkles.

[0058] Hot pressing operation: Place the film 110 with the thermosetting adhesive backing 120 applied into a flatbed hot press (or a vacuum hot press for high precision requirements), set the temperature to 50~60℃ and the pressure to 1~3 bar, and hold for 5~20 seconds. The flatness error of the heating plate of the hot press should be ≤0.02mm / m to ensure uniform pressure distribution.

[0059] Stage results: The thermosetting adhesive 120 initially softens and forms a temporary bond with the film 110, with an adhesion strength of 3~5 N / cm, which is sufficient to support subsequent positioning operations. Furthermore, the thermosetting adhesive 120 is not completely cured, retaining its activity for subsequent bonding with the carrier substrate.

[0060] Component positioning stage (step S220)

[0061] Carrier preparation: Fix the carrier substrate 130 to the positioning worktable, and ensure that the horizontal error of the top surface of the carrier is ≤0.03mm / m by using the leveling mechanism of the worktable; if it is a ceramic substrate, the vacuum adsorption device (adsorption pressure -0.06~-0.08MPa) can be turned on to fix the carrier; if it is a plastic substrate, it is fixed by using positioning pins (diameter error ≤0.01mm) to cooperate with the positioning holes of the carrier.

[0062] Precise alignment: Using a visual positioning system (positioning accuracy ±0.01mm) or a mechanical positioning fixture, the pre-pressed "film 110-thermosetting adhesive 120" assembly is moved to the top of the carrier substrate 130. Alignment is performed according to the positioning holes, positioning grooves or edge reference lines to ensure that the relative offset error between the assembly and the carrier substrate 130 is ≤0.1mm.

[0063] Temporary fixation: After alignment, the assembly is temporarily fixed to the carrier plate substrate 130 by light pressure clamps (pressure 0.5~1 bar) or point hot pressing (temperature 50℃, time 3 seconds) to prevent displacement during subsequent movement.

[0064] Final bonding stage (step S230)

[0065] Equipment adjustment: Send the positioned assembly into the hot press equipment. If the substrate 130 is ceramic, vacuum hot press equipment (vacuum degree ≤10Pa) should be selected first to avoid air bubbles in the adhesive layer. Set the hot press temperature to 75~110℃ (heating rate 5~10℃ / min to avoid sudden temperature changes that may cause component deformation) and the pressure to 2~5 bar (pressure holding accuracy ±0.1 bar).

[0066] Curing process: Maintain the set temperature and pressure for 10~480 seconds. The specific time should be adjusted according to the following conditions: when the adhesive thickness is 0.03~0.05mm, the time is 10~60 seconds; when the adhesive thickness is 0.05~0.08mm, the time is 60~240 seconds; for ceramic substrates, the time is extended to 240~480 seconds to ensure that the thermosetting adhesive 120 fully wets the surface of the carrier board.

[0067] Stage effect: The thermosetting adhesive 120 undergoes a cross-linking reaction and forms a dense adhesive layer after complete curing. It forms a chemical bond with the film 110 and the carrier substrate 130. At this stage, the adhesive strength reaches 15~25 N / cm, and the adhesive layer is free of bubbles and cracks.

[0068] Finished product formation stage (step S240)

[0069] Cooling and depressurization: After the thermosetting adhesive 120 is fully cured, control the hot press equipment to cool down to room temperature (20~25℃) at a rate of 3~5℃ / min to avoid rapid cooling causing internal stress in the composite board structure; after cooling is completed, gradually depressurize to normal pressure.

[0070] Demolding inspection: Remove the finished composite board from the hot pressing equipment, remove the positioning clamps and temporary fixing structures, check the appearance of the finished product for any glue overflow, deformation, or delamination, and use an image measuring instrument to detect positioning errors and a tensile tester to test the bonding strength (180° peel test).

[0071] Packaging and storage: Qualified finished products are packaged in anti-static packaging and stored in an environment with a temperature of 15~30℃ and a humidity of 30%~60%, avoiding direct sunlight and violent vibration.

[0072] The following detailed embodiments, combined with three different application scenarios, further illustrate the technical solution of this utility model. However, these are not intended to limit the scope of protection of this utility model. All equivalent changes and modifications made in accordance with the technical principles of this utility model should be included within the scope of this utility model.

[0073] Example (1): Bonding structure and process of FPC and alumina ceramic substrate in smartphone. This example (1) corresponds to the bonding application of FPC and ceramic mid-frame inside a smartphone, requiring high positioning accuracy, high bonding strength, and excellent temperature and humidity resistance.

[0074] 1. Component preparation

[0075] Film 110: Select an FPC film with a thickness of 0.1mm, with a precision circuit pattern printed on the surface (line width 0.15mm, line spacing 0.15mm), and two positioning holes with a diameter of 1.5mm set on the edge. The temperature resistance limit is 260℃ and the tensile strength is 60MPa.

[0076] Thermosetting adhesive 120: Epoxy-phenolic resin composite thermosetting adhesive, thickness 0.05mm, initial melting point 50℃, complete curing temperature 90℃, Shore hardness D 70 after curing, dielectric strength 25kV / mm.

[0077] Carrier substrate 130: Select an alumina ceramic plate (Al2O3 content 96%), size 120mm×60mm×2.5mm, top surface sandblasted to roughness Ra 0.4~1.2μm, set with 2 positioning pins with diameter 0.8mm (error ±0.01mm), levelness error ≤0.03mm / m.

[0078] 2. Manufacturing Process Steps

[0079] Pre-pressing bonding stage (step S210): In a Class 1000 cleanroom, the thermosetting adhesive 120 is aligned and laid on the bottom surface of the FPC film with a deviation of ≤0.2mm; it is placed in a flatbed hot press, the temperature is set to 55℃ and the pressure to 2bar, and it is held for 10 seconds; after removal, it is checked and the adhesive is tightly bonded to the FPC without wrinkles or bubbles, and the initial bonding strength is 4N / cm.

[0080] Component positioning stage (step S220): Fix the ceramic carrier plate to the positioning worktable with vacuum adsorption (adsorption pressure -0.07MPa), and align the positioning holes of the FPC-adhesive assembly with the positioning pins of the ceramic carrier plate through the vision positioning system (accuracy ±0.01mm), with an alignment error ≤0.08mm; temporarily fix it with a light pressure clamp at a pressure of 0.8bar.

[0081] Final bonding stage (step S230): The assembly is sent into a vacuum hot press, the vacuum degree is set to 5 Pa, the temperature is raised to 90°C (heating rate 8°C / min), the pressure is 3 bar, and it is held for 60 seconds; during this period, the temperature and pressure stability are monitored, and the errors are ≤ ±1°C and ±0.1 bar, respectively.

[0082] Finished product formation stage (step S240): Cool down to 25°C at a rate of 4°C / min, remove the finished product after depressurization; remove the fixture, check the appearance for no excess glue or deformation, and ensure the FPC circuit pattern is intact; detect the positioning error as 0.06mm using an image measuring instrument, and test the 180° peel strength as 18N / cm using a tensile tester; after packaging, store in an environment of 25°C and 50% RH.

[0083] Example (II): High-strength bonding structure and process for FPC and (PC, PC / ABS) plastic carrier in industrial control equipment. This Example (II) corresponds to the bonding application of FPC and plastic carrier in industrial control equipment, requiring high bonding strength, excellent temperature resistance, and suitability for long-term high-load working environments.

[0084] 1. Component preparation

[0085] Film 110: FPC film with a thickness of 0.12mm, printed circuit pattern on the surface (line width 0.15mm, line spacing 0.15mm), temperature limit 130℃, tensile strength 65MPa.

[0086] Thermosetting Adhesive 120: Epoxy resin thermosetting adhesive, thickness 0.06mm, initial melting point 55℃, complete curing temperature 110℃, Shore hardness D 75 after curing, dielectric strength 28kV / mm.

[0087] Carrier substrate 130: (PC, PC / ABS) plastic carrier, size 200mm×150mm×4mm, textured finish (VDI 15~21), with a vacuum adsorption area, and a levelness error ≤0.03mm / m.

[0088] 2. Manufacturing Process Steps

[0089] Pre-pressing bonding stage (step S210): In a cleanroom, the thermosetting adhesive 120 is laid on the bottom of the FPC, placed in a hot press, and the temperature is set to 60°C and the pressure to 3 bar, and held for 5 seconds; the initial bonding strength is 5 N / cm, with no bubbles or misalignment.

[0090] Component positioning stage (step S220): Fix the (PC, PC / ABS) plastic carrier plate on the vacuum adsorption worktable (adsorption pressure -0.08MPa), align the FPC-thermosetting adhesive 120 assembly with an error ≤0.09mm using a vision positioning system; temporarily fix it with dot-shaped hot pressing (50℃, 3 seconds).

[0091] Final bonding stage (step S230): The thermosetting adhesive 120 is fed into a hot press and heated to 110°C (heating rate 10°C / min) with a pressure of 5 bar for 10 seconds to ensure rapid and complete curing.

[0092] Finished product formation stage (step S240): Cool down to 25°C at a rate of 5°C / min, release pressure and remove; check that the appearance is intact and the adhesive strength is 22N / cm; after a high temperature test at 120°C for 24 hours, the adhesive strength remains at 20N / cm and there is no delamination.

[0093] Example (3): A tamper-proof security circuit box for a payment transaction device. This example corresponds to payment transaction scenarios such as self-service payment terminals, parking lot charging equipment, and electronic payment terminals. The core requirement is to have a highly reliable tamper-proof function, while ensuring stable circuit connection, resistance to environmental aging, and suitability for outdoor or high-frequency use scenarios. The tamper-proof security circuit box for the payment transaction device includes a plastic part and a PI flexible board. The PI flexible board is disposed on the inner side of the plastic part, and the inner side of the plastic part is provided with a groove for placing the PI flexible board. An tamper-proof circuit is provided on the side of the PI flexible board away from the plastic part, wherein the tamper-proof circuit is integrally formed with the PI flexible board, and the tamper-proof circuit also includes a payment transaction device, which is connected to the tamper-proof circuit. That is to say, the PI flexible board is a film, the carrier substrate is the plastic part, and a thermosetting adhesive is pressed onto the PI flexible board using a hot press device at 50~60 degrees Celsius, a pressure of 1~3 Bar, and a time of 5~20 seconds. Next, the PI flexible board and the thermosetting adhesive are positioned and placed on the plastic part after being pressed together. Then, in a final bonding stage, the thermosetting adhesive is made to reach the preset bonding strength by using a hot press at 75~110 degrees Celsius and 2~5 Bar for 10~480 seconds, so that the PI flexible board and the plastic part are bonded together to form a finished product.

[0094] [Component Preparation]

[0095] PI Flexible Board (Film 110): A high-temperature resistant PI flexible board with a thickness of 0.08mm is available, with a temperature resistance limit ≥180℃ and tensile strength ≥70MPa, ensuring no deformation or embrittlement during hot pressing and long-term use. The PI flexible board surface features an integrally printed anti-tampering circuit with a line width of 0.1mm and a line spacing of 0.1mm. The circuit layout is tightly fitted to the edges and core areas of the flexible board, with no blind spots. The anti-tampering circuit is electrically connected at both ends to the main control module of the payment transaction device, forming a closed loop. When the PI flexible board is torn, cut, or delaminated by external force, the circuit will be broken in real time, triggering the main control module to issue an alarm signal (such as device locking, remote backend alarm, and on-site audible and visual prompts), eliminating the risk of unauthorized tampering with transaction data or theft of fees.

[0096] Plastic component (carrier substrate 130): Made of PC / ABS alloy material, combining impact resistance and dimensional stability, suitable for outdoor high and low temperature environments (-20~60℃). The inner side of the plastic component has a pre-set groove for placing the PI flexible board. The dimensional accuracy of the groove is ≤0.05mm. The top surface is textured (VDI 18) to improve the adhesion of the adhesive. Two 1.2mm diameter positioning pins (error ±0.01mm) are set on the edge of the groove for precise alignment of the PI flexible board. The overall dimensions of the plastic component are designed to be 80mm×60mm×5mm according to the internal installation space of the payment transaction device. It is lightweight and easy to assemble.

[0097] Thermosetting Adhesive 120: Selected polyurethane thermosetting adhesive, 0.04mm thick, initial melting point 52℃, complete curing temperature 85℃, Shore hardness D 65 after curing, dielectric strength ≥22kV / mm, with good flexibility and adhesion strength, can match the coefficient of thermal expansion of PI flexible board and PC / ABS plastic parts, avoiding delamination due to temperature changes during long-term use.

[0098] [Process Steps]

[0099] Preparation: Place the PI flexible board, thermosetting adhesive, and plastic parts in a Class 1000 cleanroom (temperature 22~25℃, humidity 45%~55%) and let it stand for 2 hours to remove surface dust and moisture. Check that the anti-tampering circuit of the PI flexible board is continuous and without breaks, that the thermosetting adhesive is free of bubbles and impurities, and that there are no burrs or residual adhesive in the grooves of the plastic parts.

[0100] Pre-pressing and bonding stage: The thermosetting adhesive side is tightly laid on the non-circuit side (bottom) of the PI flexible board using an automated alignment device, ensuring that the deviation between the edge of the adhesive and the edge of the PI flexible board is ≤0.2mm, with no wrinkles or offset; the assembly is placed in a flat plate hot press (heating plate flatness error ≤0.02mm / m), the temperature is set to 55℃ and the pressure to 2Bar, and it is held for 12 seconds to allow the adhesive to soften initially and form a temporary bond with the PI flexible board. The initial bonding strength reaches 4N / cm, which facilitates subsequent positioning operations.

[0101] Component positioning stage: Fix the plastic part on a positioning worktable with vacuum adsorption (adsorption pressure -0.07MPa). Using a vision positioning system (positioning accuracy ±0.01mm), move the pre-pressed "PI flexible board - thermosetting adhesive backing" assembly into the groove of the plastic part, so that the positioning hole of the PI flexible board and the positioning pin of the plastic part are precisely matched, ensuring that the relative offset error between the two is ≤0.08mm. Then, temporarily fix it with a light pressure clamp of 0.6Bar to avoid displacement during the movement.

[0102] Final bonding stage: The entire assembly is placed into a hot press, the heating rate is set to 6℃ / min, the temperature is raised to 85℃, the pressure is 3 Bar, and it is held for 30 seconds (because the adhesive is thin and the plastic parts have good thermal conductivity, there is no need to extend the curing time); during the process, the temperature and pressure stability are monitored, and the error is controlled within ±1℃ and ±0.1 Bar respectively to ensure that the adhesive is fully cross-linked and cured.

[0103] Finished Product Formation Stage: After the adhesive backing is fully cured, the hot pressing equipment is cooled to room temperature (25℃) at a rate of 4℃ / min to avoid internal stress caused by rapid cooling between the PI flexible board and the plastic parts. After cooling, the pressure is gradually released to normal pressure, the finished product is removed, and the positioning fixtures are taken out. Subsequent testing shows no excess adhesive or deformation, and the anti-tampering circuitry of the PI flexible board is functioning normally. The positioning error is 0.06mm, as measured by an image measuring instrument, and the 180° peel strength is 16N / cm, as measured by a tensile tester. After 240 hours of high temperature and high humidity testing at 85℃ and 85%RH, no delamination or short circuits were observed. Finally, anti-static packaging is used, and the product is stored in an environment of 15~30℃ and 30%~60% humidity to ensure product quality upon delivery.

[0104] When the PI flexible circuit board is damaged by external force (such as tearing, cutting, or prying), the anti-tampering circuit integrated with it will be immediately disconnected. After receiving the disconnection signal, the main control module of the payment transaction device can simultaneously activate a dual protection mechanism: first, the transaction function is locked in real time to prevent subsequent payment operations; second, the tampering alarm information is sent to the management backend through the communication module, including the device number, timestamp, and abnormal location, so that staff can handle it in a timely manner. This achieves the anti-tampering requirements of the payment transaction device from both structural and functional perspectives.

[0105] In summary, the composite board structure bonded with thermosetting adhesive provided by this utility model can bring the following benefits:

[0106] 1. Balance between temperature and protection: The low temperature design of 50~60℃ in the pre-compression stage perfectly matches the temperature resistance limit of precision films such as FPC, avoiding damage to circuit patterns and solving the core defects of traditional high-temperature curing; the appropriate temperature curing of 75~110℃ in the final bonding stage ensures that the thermosetting adhesive is fully cross-linked, and the bonding strength reaches 15~25N / cm, which is 2~3 times that of traditional instant adhesives and pressure-sensitive adhesives.

[0107] 2. Significantly improved positioning accuracy: The design of "pre-compression and fixation followed by positioning" avoids the offset caused by the flow of colloid. Combined with the vision positioning system and high-precision positioning structure, the positioning error is controlled within 0.1mm, which is far better than the error range of 0.5~1mm of traditional technology, and fully meets the assembly requirements of precision electronic components.

[0108] 3. Wide material compatibility: The thermosetting adhesive formula is matched with the surface treatment of the carrier substrate. The adhesion strength to plastic substrates such as ABS, PC, and PC / ABS is ≥15N / cm, and the adhesion strength to ceramic substrates such as alumina and aluminum nitride is ≥18N / cm, which solves the problem of poor compatibility of traditional adhesive materials with heterogeneous substrates.

[0109] 4. Excellent durability and environmental adaptability: The cured adhesive layer has excellent temperature resistance, humidity resistance and aging resistance. The adhesive strength decreases by ≤10% in a wide temperature range of -40~120℃. After 1000 hours of high temperature and high humidity test (85℃, 85%RH), there is no delamination or glue overflow. The service life is more than 8 years, meeting the long-term reliability requirements of the electronics, automotive and other fields.

[0110] 5. Simplified process and improved yield: The phased process flow is clear and can be integrated with automated production lines to reduce human error; the product yield has been increased from below 85% in traditional technology to over 95%, production efficiency has been increased by 30%, and manufacturing costs have been reduced.

[0111] 6. Expanded application scenarios: It is not only suitable for bonding FPC to substrates, but can also be extended to composite structures of other functional films (such as optical films and waterproof films) and different substrates, covering multiple fields such as electronics, automobiles, industrial control, and consumer electronics, with broad application prospects.

[0112] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the scope of the present utility model. Therefore, all equivalent variations or modifications made in accordance with the features and spirit described in the claims of the present utility model should be included within the scope of the present utility model.

Claims

1. A composite board structure bonded with thermosetting adhesive, used in a payment transaction anti-tampering device, characterized in that, The composite board structure bonded with thermosetting adhesive includes: A thin film with a thickness ranging from 0.05 to 0.2 mm serves as both an anti-tampering functional carrier layer and a signal transmission medium. A thermosetting adhesive, one side of which is disposed on the bottom surface of the film, is pressed onto the film using a hot press at 50-60 degrees Celsius, a pressure of 1-3 Bar, and a time of 5-20 seconds, wherein the thickness of the thermosetting adhesive ranges from 0.03 to 0.15 mm; and A carrier substrate has its top positioned on the other side of the thermosetting adhesive. The film and the thermosetting adhesive are positioned on the carrier substrate and then subjected to a hot press at 75-110 degrees Celsius and 2-5 Bar for 10-480 seconds to achieve a preset adhesive strength, thereby bonding the film and the carrier substrate together to form a finished product.

2. The composite board structure bonded with thermosetting adhesive as described in claim 1, characterized in that, The film is provided with an anti-tampering function unit, which is an integrally formed conductive line or conductive coating, and is signal-connected to the control unit of the payment transaction anti-tampering device. The control unit is capable of activating anti-tampering protection measures in real time.

3. The composite board structure bonded with thermosetting adhesive as described in claim 1, characterized in that, The film is a flexible printed circuit board film, and has a printed circuit pattern.

4. The composite board structure bonded with thermosetting adhesive as described in claim 1, characterized in that, The substrate material of the carrier plate is either a plastic substrate or a ceramic material.

5. The composite board structure bonded with thermosetting adhesive as described in claim 1, characterized in that, The thermosetting adhesive is pressed onto the film by aligning one side of the thermosetting adhesive with the bottom surface of the film manually or using automated equipment, to ensure that the deviation between the edge of the thermosetting adhesive and the edge of the film is ≤0.2mm.

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