A performance detection system for hot melt double-sided tape for lithium battery modules

Abstract

This invention belongs to the field of battery manufacturing and testing technology, specifically a performance testing system for hot-melt double-sided adhesive tape used in lithium battery modules. The system includes a dynamic hot-press bonding module, an environmental simulation and isolation chamber, an in-situ microenvironment mechanical loading module, a multi-physics field coupled sensing and acquisition module, and a central process control and data processing unit. The dynamic hot-press bonding module can accurately reproduce the temperature-pressure-time process curve; the environmental simulation chamber enables in-situ testing at temperatures ranging from -40°C to 150°C; the in-situ mechanical loading module supports 180-degree peeling, shearing, and creep testing; the multi-physics field sensing module simultaneously acquires interface temperature, pressure distribution, force, and displacement signals; and the central control unit achieves fully automated control and data analysis throughout the entire process. Through this integrated design, this application can comprehensively simulate hot-press bonding and dynamic service environments, and perform in-situ mechanical performance characterization, truly reflecting the performance of the tape throughout the entire lifecycle of the lithium battery module.

Description

Technical Field

[0001] This invention belongs to the field of battery manufacturing and testing technology, specifically a performance testing system for hot melt double-sided adhesive tape used in lithium battery modules. Background Technology

[0002] The development of the new energy vehicle and energy storage industries has driven increased demands for safety, reliability, and energy density in lithium battery modules. Structural adhesives are commonly used between cells and between cells and structural components. Hot-melt double-sided adhesive tape has become a core adhesive material due to its good operability at room temperature, high bonding strength after heating, and insulating and buffering properties. Its adhesive performance directly determines the structural integrity and thermal management efficiency of the module under vibration, temperature cycling, and extreme operating conditions. Therefore, accurate quantitative testing of its adhesive performance is a key guarantee for module design verification, quality control, and process optimization.

[0003] The current mainstream method for testing adhesive performance is the 180-degree peel strength test specified in standards such as GB / T2792. This involves preparing a sample by bonding hot melt adhesive tape between a standard substrate and a flexible substrate under constant temperature and humidity conditions in a laboratory. The flexible substrate is then peeled off at a constant rate using a universal testing machine, and the force value is recorded and the average peel force per unit width is calculated. This method is clear in principle, standardized in operation, and has good repeatability. As a traditional method for evaluating adhesive performance, it provides effective data support for material screening and basic quality assessment.

[0004] However, as lithium battery technology places increasingly stringent demands on energy density and safety performance, cell arrangement is becoming increasingly compact, and the operating temperature and temperature gradient within the module are becoming more complex. The traditional testing methods based on idealized and static experimental conditions, as described above, gradually reveal their inherent limitations when simulating the actual service behavior of hot-melt double-sided adhesive tape within a lithium battery module. The reason for this is that the core logic of traditional testing methods completely separates sample preparation and performance testing. The peel strength measured is essentially a static, final-state theoretical performance peak that the tape can achieve under optimal curing conditions. This testing paradigm ignores two crucial dimensions: firstly, the dynamic bonding process of the tape on the actual assembly line. In automated module production, the activation of the hot-melt adhesive tape is achieved through a precisely controlled temperature-pressure-time process window. The heating rate, peak temperature, holding time, and cooling rate collectively determine the degree of wetting, diffusion, and entanglement of the adhesive molecular chains, thus directly affecting the final interfacial bonding quality. Traditional testing methods, using pre-prepared ideal samples, cannot fully replicate the sensitivity of this dynamic process to the final bonding effect. Secondly, there is the dynamic service environment of the tape throughout the module's lifecycle. Lithium batteries generate heat during charging and discharging, causing significant temperature fluctuations within the module. The tape needs to maintain its bonding integrity under these alternating temperature cycles and thermal stresses. Especially at high temperatures, the modulus of hot melt adhesives decreases significantly, making its creep characteristics particularly prominent. Traditional room temperature peel tests are completely incapable of characterizing the tape's bonding retention and creep resistance within the actual operating temperature range (exemplarily 45°C to 80°C). This significant disconnect between test results and actual operating conditions can lead to a tape with extremely high room temperature peel strength data exhibiting a risk of bonding failure during the actual high-temperature operation of the battery module, resulting in cell displacement, increased thermal resistance, and even, in extreme cases, thermal runaway and other serious safety issues.

[0005] Therefore, the present invention provides a performance testing system for hot melt double-sided adhesive tape used in lithium battery modules. Summary of the Invention

[0006] In order to overcome the shortcomings of the prior art, at least one technical problem raised in the background art is solved.

[0007] The technical solution adopted by the present invention to solve its technical problem is: a performance testing system for hot melt double-sided adhesive tape for lithium battery modules, comprising a dynamic hot-press bonding module, an environmental simulation and isolation cavity, an in-situ micro-environment mechanical loading module, a multi-physics field coupling sensing and acquisition module, and a central process control and data processing unit.

[0008] Specifically, the dynamic hot-press bonding module is used to accurately reproduce the temperature-pressure-time coupled process curve of hot-melt double-sided adhesive tape on an automated lithium battery module production line. The dynamic hot-press bonding module includes an upper pressure head assembly and a lower pressure head base, which are arranged opposite to each other, together forming an area for applying heat and pressure to the substrate holding the adhesive tape sample to be tested. The core structure of both the upper pressure head assembly and the lower pressure head base is a hot-pressing platform made of dispersion-reinforced oxygen-free copper, with its surface hard anodized to form a 50-micron-thick insulating and wear-resistant layer. Inside the hot-pressing platform, an integrated matrix-arranged microchannel network is formed, which is connected to an external dynamic temperature control unit via flexible fluororubber tubing resistant to high and low temperatures. The dynamic temperature control unit includes a high-precision compressor refrigeration unit and an electric heating circulating heater. By precisely controlling the temperature and flow rate of the silicone oil medium within the range of -60℃ to 200℃, it achieves a heating rate of up to 20℃ / s and a cooling rate of 15℃ / s on the hot pressing platform, thereby accurately simulating the rapid heating activation and forced cooling curing stages in the production process.

[0009] Furthermore, the upper pressure head assembly is fixed to the output shaft end of a high-precision electric cylinder driven by an AC servo motor via a high-rigidity connecting flange. The high-precision electric cylinder incorporates a ball screw drive mechanism and a torque sensor. The AC servo motor, receiving commands from the central process control and data processing unit, drives the ball screw to achieve the vertical lifting and lowering movement of the upper pressure head assembly. Based on closed-loop feedback from the torque sensor, precise control of the pressing force is achieved within the range of 10N to 5000N, with a control accuracy reaching 0.1% of full scale. The lower pressure head base is fixedly mounted on the bottom plate of the environmental simulation and isolation chamber, and its surface integrates an array of electromagnetic chucks for fixing the lower test substrate. This structural design ensures that the pressure loading rate, holding time, pressure value, and temperature change curves throughout the entire hot-press bonding process can be precisely programmed and reproduced.

[0010] The environmental simulation and isolation chamber is a fully sealed stainless steel cubic container with a double-walled structure. The space between the inner and outer walls is evacuated to 10^-3 Pa and filled with aerogel insulation material to minimize heat exchange with the external environment. The inner wall surface of the environmental simulation and isolation chamber undergoes electrolytic polishing to reduce its emissivity. An independent air temperature control system is installed inside the environmental simulation and isolation chamber. This system includes a high-temperature centrifugal fan, a set of finned electric heating elements, and a set of finned heat exchangers cooled by an external chiller. The centrifugal fan drives forced convection circulation of air within the environmental simulation and isolation chamber, and the temperature is regulated by the electric heating elements or heat exchangers. This establishes a stable or dynamically changing temperature field environment within the environmental simulation and isolation chamber, ranging from -40℃ to 150℃, with a temperature uniformity better than ±0.5℃, to simulate the operating temperature of lithium battery modules under different conditions. The environmental simulation and isolation chamber is equipped with multiple standard interface flanges, which are used to install the transmission mechanism of the in-situ microenvironment mechanical loading module, various sensor probes of the multi-physics field coupling sensing and acquisition module, and pipelines for vacuuming and filling with a specific atmosphere (such as dry nitrogen).

[0011] The in-situ microenvironment mechanical loading module is designed to perform mechanical property testing directly on the adhesive tape sample after hot-press bonding within the specific temperature field created by the environmental simulation and isolation chamber, without transferring or disrupting the temperature field environment. The in-situ microenvironment mechanical loading module includes a horizontally positioned precision linear moving platform and a flexible substrate clamping and force measuring component. The precision linear moving platform consists of a stepper motor driving a ground ball screw via a coupling, and the entire platform is mounted on one inner wall of the environmental simulation and isolation chamber. The flexible substrate clamping and force measuring component is fixed to the slider of the precision linear moving platform via a connecting arm. The clamping component is a pneumatic wedge clamp, whose pneumatic pipeline is connected to an external air source through a pneumatic connector on the chamber wall. The force measuring component is an S-type high-precision force sensor with a range of 200N and a nonlinearity error of less than 0.01%FS. This force sensor is connected in series between the connecting arm and the pneumatic wedge clamp for real-time measurement of the force value during peeling or shearing processes. During the 180-degree peel test, the rigid substrate with the adhesive tape to be tested is fixed to the pressure head base, while the free end of the flexible substrate is held by the pneumatic wedge clamp. The central process control and data processing unit instructs the stepper motor to drive the linear moving platform horizontally at a preset constant rate (exemplarily 5 mm / s), thereby achieving the peeling of the flexible substrate. The entire loading and measurement process is completed in situ at a set ambient temperature.

[0012] Furthermore, different adapter fixtures can be interchangeably installed between the precision linear moving platform and the pressure head base of the in-situ microenvironment mechanical loading module to achieve other mechanical performance testing modes besides the 180-degree peel strength test. For example, by installing a shear test fixture, the lap shear strength of the tape sample can be measured in situ; by installing a creep test fixture, the creep displacement of the tape can be monitored for a long time under specific temperature and constant tensile load to evaluate its high-temperature creep resistance.

[0013] The core function of the multi-physics coupling sensing and acquisition module is to perform high-precision, high-time-synchronization real-time monitoring of key physical quantities throughout the entire hot-pressing bonding and in-situ testing process. This module includes an interface temperature sensing unit, an interface pressure distribution sensing unit, a displacement sensing unit, and a data synchronization acquisition unit. The interface temperature sensing unit contains two different types of temperature sensors: one is a non-contact infrared thermometer, whose probe focuses on the edge of the bonding interface between the tape and the substrate during hot pressing through a calcium fluoride observation window at the top of the environmental simulation and isolation chamber, used to directly measure the true temperature of the adhesive, with a measurement range of 0℃ to 350℃ and a response time of less than 50 milliseconds; the other is an armored K-type miniature thermocouple, with a diameter of 0.5 mm, pre-embedded inside the upper and lower test substrates, with its tip only 0.2 mm from the bonding surface, used to accurately measure the temperature gradient of the substrate near the bonding interface.

[0014] The interface pressure distribution sensing unit is an ultra-thin, flexible pressure distribution film sensor that can be placed between the lower test substrate and the pressure head base. This sensor integrates a 16x16 sensor array, enabling real-time, visual measurement and display of the pressure distribution uniformity throughout the bonding area during hot pressing with a spatial resolution of 1 mm². The displacement sensing unit comprises two parts: first, a laser displacement sensor for measuring peel displacement, with its transmitter and receiver installed inside the environmental simulation and isolation cavity. The measuring spot is projected onto specific marked points on the flexible substrate clamping and force measuring components, recording the displacement during the peeling process in real time with a resolution of 0.1 micrometers; second, a high-precision linear variable differential transmitter (LVDT) for measuring creep displacement, used during creep testing. The data synchronization acquisition unit is a high-speed data acquisition system based on the PXI bus architecture. It includes a multi-functional analog input module, a digital I / O module, and a counter / timer module. It can synchronously acquire all signals from force sensors, infrared thermometers, thermocouples, pressure distribution sensors, and displacement sensors at a sampling rate of up to 100kHz, and assign a unified timestamp to all data points to ensure the accurate correspondence of multi-physics data in the time dimension.

[0015] The central process control and data processing unit is the control hub and data processing core of the entire testing system. Its hardware is based on a high-performance industrial control computer, running a dedicated measurement and control analysis software developed based on the LabVIEW software platform. The core functional modules of this software include: a process curve editor, an environmental simulation sequence controller, a closed-loop feedback control algorithm engine, and a data analysis and report generator. The process curve editor allows users to freely define and edit multiple temperature-time and pressure-time curves during the hot-pressing bonding process using a graphical interface, precisely corresponding to the process parameters of a specific production line. The environmental simulation sequence controller is used to set the environmental temperature points or temperature cycling curves during the in-situ testing phase.

[0016] The closed-loop feedback control algorithm engine is key to achieving high-precision process reproduction. During the hot-pressing stage, the engine executes a cascaded PID control strategy: its outer-loop PID controller uses the actual adhesive temperature measured by the infrared thermometer as a process variable (PV), compares it with the target temperature set in the process curve, and its output value serves as the setpoint (SP) of the inner-loop PID controller. The inner-loop PID controller uses the temperature of the thermocouple embedded inside the hot-pressing platform as its process variable (PV), and precisely tracks the setpoint output of the outer loop by adjusting the power of the heater or chiller in the dynamic temperature control unit. This cascaded control method effectively overcomes the hysteresis caused by thermal inertia, achieving precise control of the actual temperature of the bonding interface. Similar closed-loop control logic is also applied to pressure control, where the torque sensor built into the high-precision electric cylinder serves as feedback, ensuring that the applied pressure precisely matches the set pressure curve. During the in-situ testing stage, the engine is responsible for precisely controlling the speed of the stepper motor to achieve a constant peeling or shearing rate.

[0017] The data analysis and report generator automatically processes the massive amounts of raw data recorded by the data synchronization acquisition unit after the test is completed. It can automatically calculate and extract key performance indicators, such as average peel strength, peak peel force, adhesive energy, shear strength at different temperatures, and creep strain over time. Furthermore, the software can correlate force-displacement curves with temperature and pressure curves during hot pressing, as well as interfacial pressure distribution cloud maps, thereby revealing the intrinsic influence of minute fluctuations in process parameters on the final bonding performance. This provides unprecedented, deeply physically meaningful data support for material selection, process window optimization, and failure analysis.

[0018] The beneficial effects of this invention are as follows:

[0019] This invention discloses a performance testing system for hot-melt double-sided adhesive tape used in lithium battery modules. By unprecedentedly integrating three major functions—dynamic hot-pressing process simulation, wide-temperature-range environment simulation, and in-situ mechanical characterization—into a closed, automated system, it fundamentally solves the problem of severe disconnect between testing conditions and actual operating conditions in previous technologies. It not only measures the final performance of the tape but, more importantly, reveals the intrinsic relationship between this performance and its formation process and service environment. This provides high-value performance data that truly reflects its behavior throughout the entire lifecycle of the lithium battery module, offering an indispensable scientific tool and quality control method for the research and development and manufacturing of high-performance, high-safety lithium battery modules. Attached Figure Description

[0020] The invention will now be further described with reference to the accompanying drawings.

[0021] Figure 1 This is a structural block diagram of a performance testing system for hot melt double-sided adhesive tape used in battery modules according to the present invention;

[0022] Figure 2 This is a schematic diagram of the environmental simulation and isolation cavity structure in this invention;

[0023] Figure 3 This is a schematic diagram of the dynamic hot-press bonding module in this invention;

[0024] Figure 4 This is a schematic diagram of the in-situ microenvironment mechanical loading module in this invention;

[0025] Figure 5 This is a schematic diagram of the structure of the multi-physics field coupling sensing and acquisition module in this invention;

[0026] Figure 6 This is a schematic diagram of the central process control and data processing unit structure in this invention;

[0027] Figure 7 This is a schematic diagram of the workflow of the detection method of the present invention;

[0028] In the diagram: 10. Dynamic hot-press bonding module; 11. Upper pressure head assembly; 12. Lower pressure head base; 13. Hot-press platform; 14. Microfluidic network; 15. High-precision electric cylinder; 16. Electromagnetic chuck array; 20. Environmental simulation and isolation chamber; 22. Air temperature control system; 23. Interface flange; 24. Calcium fluoride observation window; 30. In-situ microenvironment mechanical loading module; 31. Precision linear moving platform; 32. Flexible substrate clamping force measuring assembly; 33. Pneumatic wedge clamp. Features: 34. S-type high-precision force sensor; 40. Multi-physics field coupling sensing and acquisition module; 41. Non-contact infrared thermometer; 42. Armored K-type miniature thermocouple; 43. Flexible pressure distribution film sensor; 44. Laser displacement sensor; 45. Data synchronous acquisition unit; 50. Central process control and data processing unit; 51. Industrial control computer; 52. Measurement and control and analysis software; 100. Adhesive tape sample to be tested; 101. Rigid substrate; 102. Flexible substrate. Detailed Implementation

[0029] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0030] Reference Figures 1 to 7 This invention discloses a performance testing system for hot-melt double-sided adhesive tape used in lithium battery modules. This system, through a highly integrated precision electromechanical and measurement and control architecture, achieves precise, integrated, and in-situ characterization of the bonding performance of hot-melt double-sided adhesive tape under simulated real production processes and service environments. The system's macroscopic structure includes a system frame... Figure 1 As shown, it mainly includes a dynamic hot-press bonding module 10, an environmental simulation and isolation cavity 20, an in-situ micro-environment mechanical loading module 30, a multi-physics field coupling sensing and acquisition module 40, and a central process control and data processing unit 50 as the system control center.

[0031] The environmental simulation and isolation chamber 20 constitutes the core physical boundary of the entire system. It houses the key components of the dynamic hot-press bonding module 10, which performs the dynamic hot-press bonding function, and the in-situ micro-environment mechanical loading module 30, used for in-situ mechanical testing. Various sensor probes of the multi-physics coupling sensing and acquisition module 40 are precisely deployed at key locations inside the chamber 20 via preset interfaces to capture various physical parameters during the testing process in real time. The execution of actions and data flow of all modules are uniformly scheduled, controlled, and analyzed by the central process control and data processing unit 50.

[0032] Specifically, the core function of the dynamic hot-press bonding module 10 is to accurately reproduce and programmatically control the dynamic temperature-pressure-time coupling process curve experienced by the hot melt double-sided adhesive tape 100 on the automated production line.

[0033] Reference Figure 3 This module mainly consists of an upper pressure head assembly 11 and a lower pressure head base 12, which are arranged vertically opposite each other, jointly defining the core area for applying heat and pressure to the substrates (rigid substrate 101 and flexible substrate 102) holding the adhesive tape sample 100 to be tested. To achieve rapid and uniform temperature transfer and response, the core component of the upper pressure head assembly 11 and the lower pressure head base 12—the hot pressing platform 13—is made of GlidCop® AL-15 dispersion-reinforced oxygen-free copper, which has extremely high thermal conductivity (≥385 W / (m·K)) and excellent mechanical properties. This material significantly improves the material's resistance to softening and creep at high temperatures by dispersing nano-sized alumina particles within the oxygen-free copper matrix, ensuring that the surface flatness of the hot pressing platform 13 remains within 5 micrometers during repeated thermal cycling at temperatures up to 200°C. To meet the requirements of electrical insulation and wear resistance, the surface of the hot pressing platform 13 that contacts the sample undergoes a precise hard anodizing process to form a dense ceramic insulating layer with a thickness of 50±5 micrometers and a Vickers hardness of not less than 400HV. Its breakdown voltage is higher than 1000V, which effectively avoids the risk of electrical short circuits that may occur when testing simulated battery cells and greatly enhances the scratch resistance of its surface.

[0034] In some embodiments, to achieve rapid dynamic adjustment of the temperature of the hot-pressing platform 13, a complex matrix-arranged microchannel network 14 is integrally constructed within it using precision micro-milling technology. The microchannel network has a cross-sectional dimension of 1.5 mm × 1.5 mm and a channel spacing of 3 mm. This high-density layout ensures that the heat transfer medium can flow fully and uniformly throughout the entire platform volume, thereby maximizing heat exchange efficiency. The inlet and outlet of the microchannel network 14 are precisely connected to an external high-performance dynamic temperature control unit via flexible fluororubber tubing that is resistant to high and low temperatures (-70°C to +220°C) and has excellent chemical inertness. This dynamic temperature control unit integrates a high-precision compressor refrigeration unit employing cascade refrigeration technology and a 6 kW electric circulating heater, using Dow Corning PMX-200 series silicone oil as the heat transfer medium. Through the coordinated control of a high-precision electromagnetic proportional valve and a variable frequency circulating pump, this unit can precisely regulate the temperature and flow rate of the silicone oil medium flowing through the microchannel network 14, thereby achieving a programmed heating rate of up to 20°C / second and a forced cooling rate of 15°C / second for the hot pressing platform 13. This superior dynamic temperature control capability is a key technological guarantee for accurately simulating the rapid heating activation and forced air / water cooling curing processes used in modern lithium battery production lines to pursue production speed.

[0035] In some embodiments, to achieve precise control of the pressing force, the upper pressure head assembly 11 is fixed to the end of the output shaft of a high-precision electric cylinder 15 via a high-rigidity connecting flange made of 7075-T6 high-strength aluminum alloy and optimized by finite element analysis. This high-precision electric cylinder 15 consists of an AC servo motor driving a C3 precision ground ball screw transmission mechanism via a high-rigidity coupling. The servo motor has a built-in 24-bit absolute encoder, with a theoretical positioning accuracy of 0.1 micrometers.

[0036] More importantly, a high-bandwidth dynamic torque sensor is integrated in series in the transmission chain of the electric cylinder. The central process control and data processing unit 50 drives the upper pressure head assembly 11 to achieve vertical lifting and lowering motion by sending precise motion control commands to the servo driver;

[0037] During the crimping process, the control system switches to a force closed-loop control mode, using the real-time feedback signal from the torque sensor as the process variable. A high-speed PID algorithm adjusts the output torque of the servo motor, achieving precise control of the crimping force within the range of 10 Newtons to 5000 Newtons. Its control accuracy is better than 0.1% of full scale, and the force overshoot is less than 0.5%. The corresponding lower pressure head base 12 is securely mounted on the heavy-duty base plate of the environmental simulation and isolation chamber 20 to ensure sufficient rigidity. Its surface is seamlessly integrated with an electromagnetic chuck array 16 for reliably securing the lower rigid substrate 101 during hot pressing and subsequent testing. This array consists of multiple independently controlled electromagnetic units, flexibly adapting to substrates of different sizes and providing a holding force of up to 120 N / cm².

[0038] As described above, this structural design ensures that key process parameters such as pressure loading rate, holding time, peak pressure, and unloading rate throughout the hot-press bonding process can be accurately and repeatedly programmed and reproduced.

[0039] In some embodiments, the environmental simulation and isolation cavity 20, as a key container for carrying out the testing process and creating a specific service environment, is designed with full consideration of thermal isolation, sealing and functional integration.

[0040] like Figure 2 As shown, the main body of the cavity 20 is a double-walled cubic container made of stainless steel. The 50 mm thick interlayer between the inner and outer walls is evacuated to the level of 10^-3 Pa and filled with high-performance aerogel insulation felt. This vacuum + aerogel composite insulation structure has an equivalent thermal conductivity of less than 0.005 W / (m·K), thereby minimizing heat exchange between the cavity and the external environment and greatly improving the stability and energy efficiency of temperature field control.

[0041] It should be noted that, in order to further reduce radiative heat transfer between components inside the cavity, the entire inner wall surface of the cavity 20 is electrolytically polished, achieving a surface roughness Ra of less than 0.2 micrometers, thus reducing its emissivity in the infrared band to below 0.1. Inside the cavity 20, an independent air temperature control system 22 is installed for precise regulation of the internal gas environment temperature. This system includes a high-temperature resistant long-shaft centrifugal fan, a set of finned electric heating elements with a total power of 3 kW, and a set of finned heat exchangers cooled by an external industrial chiller (exemplarily providing a -50°C ethylene glycol aqueous solution). The high-temperature resistant centrifugal fan drives high-purity dry nitrogen (or dry air) within the cavity to form a high-speed forced convection circulation. The gas flows sequentially through the electric heating elements or the finned heat exchangers, thereby being precisely heated or cooled. By precisely adjusting the electric heating power and cooling medium flow valves using a PID algorithm, this system can establish a stable or dynamically changing temperature field environment within the cavity, ranging from -40℃ to +150℃, with temperature uniformity in the sample area better than ±0.5℃. This makes it possible to study the performance evolution of the tape under various simulated real-world service conditions of lithium battery modules, such as extreme cold start-up, high-temperature operation, and fast charging temperature rise.

[0042] It should also be noted that multiple interface flanges 23 are reserved on the wall of the cavity 20, which are used to install the motion feedthrough mechanism of the in-situ microenvironment mechanical loading module 30, various sensor probes (such as optical fibers, cables, etc.) of the multi-physics field coupling sensing and acquisition module 40, as well as pipelines for connecting vacuum pumps and filling with specific atmospheres (such as dry nitrogen to prevent sample oxidation).

[0043] Among them, a calcium fluoride (CaF2) observation window 24 with a diameter of 50 mm is specially installed at the top of the cavity, directly opposite the hot-pressing area. It has high transmittance in a wide spectral range of 0.2 to 7 micrometers and is specifically used for non-attenuation measurement of the non-contact infrared thermometer 41.

[0044] In some embodiments, the in-situ microenvironment force loading module 30 is unique in that it can perform mechanical property tests, including peel strength, shear strength or creep performance, on the adhesive tape sample 100 after the hot-press bonding process is completed in a specific temperature field environment created by the environmental simulation and isolation chamber 20 without removing or transferring the sample and without destroying the established stable temperature field environment.

[0045] like Figure 4As shown, the module mainly includes a horizontally positioned precision linear moving platform 31 and a flexible substrate clamping and force measuring component 32 connected to it. The precision linear moving platform 31 is mounted on one inner wall of the cavity 20 and is driven by a hybrid stepper motor through a zero-backlash bellows coupling, which drives a precision-ground THK brand ball screw. The entire platform uses a high-strength aluminum alloy frame, and the guide rails are high-precision cross roller guide rails, ensuring that it can maintain high rigidity and smooth motion characteristics in a wide temperature range (-40℃ to +150℃). The flexible substrate clamping and force measuring component 32 is fixed to the slider of the precision linear moving platform 31 through a slender titanium alloy connecting arm with a low coefficient of thermal expansion.

[0046] It should be noted that component 32 consists of a pneumatic wedge clamp 33 and an S-type high-precision force sensor 34 connected in series. The pneumatic wedge clamp 33 is designed to self-lock when the clamping force increases, providing a firm and damage-free clamping of flexible substrates 102 with thicknesses ranging from tens of micrometers to 1 millimeter. Its pneumatic lines are connected to external precision pressure regulating valves and solenoid valves via miniature quick-connect pneumatic connectors on the cavity wall. The S-type high-precision force sensor 34 is a product of MEAS, Switzerland, with a measuring range of 200 Newtons. Its nonlinearity error, repeatability error, and hysteresis error are all less than 0.01% of full scale, and it has a built-in temperature compensation circuit to ensure measurement accuracy over the entire operating temperature range.

[0047] In a specific 180-degree peel test scenario, the sample that has completed hot-press bonding (consisting of a rigid substrate 101, adhesive tape 100, and a flexible substrate 102) is placed on the pressure head base 12, wherein the rigid substrate 101 is still firmly fixed by the electromagnetic chuck array 16. The unbonded free end of the flexible substrate 102 is reliably held by the pneumatic wedge clamp 33;

[0048] As described above, at this time, the central process control and data processing unit 50 issues an instruction to drive the stepper motor on the precision linear moving platform 31 to move horizontally at a preset constant speed (exemplarily, the range can be set from 0.1 mm / min to 500 mm / min), thereby pulling the flexible substrate 102 to peel off 180 degrees relative to the fixed rigid substrate 101.

[0049] Throughout the peeling process, the S-shaped high-precision force sensor 34 measures and outputs the peeling force value in real time, while the displacement is accurately recorded by an independent displacement sensor. Since the entire loading and measurement process is completed in situ within the environmental simulation and isolation chamber 20 at a preset specific ambient temperature (exemplarily -20℃ or +85℃), the test results can truly reflect the adhesive performance of the tape at that temperature, completely eliminating the huge measurement errors and uncertainties caused by sample transfer, temperature changes, and stress release in traditional methods.

[0050] In some embodiments, the in-situ microenvironment mechanical loading module 30 is highly modular and scalable. By changing and installing different adapters between the precision linear moving platform 31 and the pressure head base 12, other key mechanical performance testing modes besides the 180-degree peel strength test can be easily implemented.

[0051] In one example, by installing a shear test fixture, which includes a fixing clamp for fixing one end of the sample and a moving clamp connected to a linear moving platform, the lap shear strength of the tape sample can be measured in situ to evaluate its shear resistance at different temperatures.

[0052] In another example, by installing a creep test fixture, which includes a constant force loading mechanism (such as using a weight or spring) and a high-precision displacement sensor, the creep displacement of the tape can be monitored for a long time (such as 100 hours) under specific high temperatures (such as 90°C) and constant tensile loads to evaluate its ability to resist the continuous stress caused by the thermal expansion and contraction of the battery cells, i.e., high-temperature creep resistance.

[0053] The core value of the multi-physics field coupled sensing and acquisition module 40 lies in the high-precision, high-temporal-resolution, high-spatial-resolution, and strictly time-synchronized real-time monitoring of key physical quantities, namely temperature, pressure, force, and displacement, throughout the entire process of hot-press bonding and in-situ testing.

[0054] like Figure 5 As shown, this module consists of multiple sensing units and a unified data acquisition unit;

[0055] Specifically, the interface temperature sensing unit includes two types of temperature sensors with complementary functions;

[0056] One is a non-contact infrared thermometer 41, optionally a CTlaser3M. Its probe, through an environmental simulation and a calcium fluoride observation window 24 at the top of the isolation chamber 20, precisely focuses on the edge area of ​​the bonding interface between the tape 100 and the substrate 101 / 102 during hot pressing. Its unique 3.9-micron short-wavelength measurement technology can effectively penetrate the upper transparent flexible substrate (such as PET or PI film) to directly measure the true temperature of the underlying hot melt adhesive. Its measurement range is 0℃ to 350℃, with a response time of less than 50 milliseconds, providing crucial feedback signals for achieving precise closed-loop control of the adhesive's true activation temperature.

[0057] Secondly, multiple armored K-type miniature thermocouples 42, each only 0.5 mm in diameter, were precisely embedded in the upper and lower test substrates 101 and 102 during the sample preparation stage, with their measuring tips only 0.2 mm away from the bonding surface. These thermocouples are used to accurately measure the temperature gradient and thermal conduction dynamics within the substrates near the bonding interface, which, together with the data from the infrared thermometer, forms a complete and accurate depiction of the interfacial thermal field.

[0058] The interface pressure distribution transmission unit employs a flexible pressure distribution thin-film sensor 43. This sensor, only 0.1 mm thick, can be directly placed between the lower rigid substrate 101 and the lower pressure head base 12. It integrates a 16x16, or 256, independent sensor array, enabling real-time, visual measurement and display of the pressure distribution cloud map across the entire bonding area during hot pressing with a spatial resolution of 1 square millimeter. This sensor allows for intuitive judgment of whether the pressure head is parallel, whether the pressure distribution is uniform, and whether stress concentration areas exist, providing valuable two-dimensional spatial information for optimizing pressure head design and process parameters.

[0059] It should be noted that the displacement sensing unit is configured according to different test modes. During the peel test, a laser displacement sensor 44 is used, with its transmitter and receiver installed in a face-to-face manner inside the cavity 20. The measuring spot is projected onto specific marked points of the flexible substrate clamping and force measuring component 32, and the precise displacement of the peel process is recorded in real time with a resolution of 0.1 micrometers and a sampling rate of up to 20 kHz, which is used to generate a high-resolution force-displacement curve.

[0060] When performing creep tests, a high-precision linear variable differential transmitter (LVDT) is used, whose core is connected to the moving fixture, providing nanometer-level displacement measurement resolution to accurately capture the tiny creep strain of the material.

[0061] All signals from the aforementioned sensors are ultimately converged to the data synchronization acquisition unit 45. This unit is a high-data acquisition system based on the NI-PXI bus architecture. Its chassis contains various functional module cards, including a PXIe-6366 multi-function analog input module for acquiring analog signals from force sensors, thermocouples, and pressure sensors; a digital I / O module for controlling solenoid valves and reading digital signals from encoders; and a counter / timer module for achieving precise timing control. This system can perform rigorous synchronous acquisition of signals from all channels at a sampling rate of up to 100kHz. Through trigger and clock signals on the PXI bus, it ensures that all acquired data points are timestamped with a uniform time stamp accurate to the microsecond level. This high degree of time synchronization is the fundamental prerequisite for subsequent multiphysics data correlation analysis, exemplarily mapping a sudden change point on the force-displacement curve precisely to a temperature or pressure fluctuation event at a specific moment during the hot-pressing process.

[0062] like Figure 6 As shown, the central process control and data processing unit 50 is the brain and nerve center of the entire testing system. The hardware foundation of this unit is an industrial control computer 51. Internally, it runs a dedicated measurement, control, and analysis software 52, deeply developed based on the LabVIEW graphical programming platform. This software has a user-friendly interface and powerful functions. Its core functional modules include a process curve editor, an environmental simulation sequence controller, a closed-loop feedback control algorithm engine, and a data analysis and report generator. The process curve editor allows users to freely define and edit complex hot-pressing bonding process curves containing up to dozens of program segments through simple drag-and-drop and parameter input in a graphical interface. For example, it precisely defines the heating / cooling rate, target temperature, holding time, pressure loading rate, holding pressure, and holding time for each segment, thereby accurately reproducing the process parameters of any specific production line. The environmental simulation sequence controller is used to set the environmental temperature points or complex temperature cycle curves for subsequent in-situ testing stages (for example, simulating the temperature shock process of a vehicle driving from a cold winter parking garage to a hot summer road).

[0063] The closed-loop feedback control algorithm engine is the core technology for achieving high-precision process reproduction. In temperature control during the hot-pressing stage, this engine innovatively implements a cascaded PID control strategy: its outer-loop PID controller uses the actual adhesive temperature measured by the non-contact infrared thermometer 41 as the process variable (PV), compares it with the target temperature (SP) set by the user in the process curve, and its output value serves as the setpoint (SP) of the inner-loop PID controller; the inner-loop PID controller uses the temperature of the fast-response thermocouple embedded inside the hot-pressing platform 13 as its process variable (PV), and precisely tracks the dynamic setpoint output by the outer-loop PID controller by rapidly adjusting the PWM duty cycle of the heater in the dynamic temperature control unit or the proportional valve opening of the refrigeration circuit. This cascaded control method effectively overcomes the control lag problem caused by the significant thermal inertia and thermal resistance between the hot-pressing platform and the adhesive interface, achieving fast, accurate, and overshoot-free control of the final target, namely the actual temperature of the bonding interface.

[0064] Similar pressure control logic is also applied to pressure control. The torque sensor built into the high-precision electric cylinder 15 provides feedback, and the torque loop inside the servo driver ensures that the pressure applied to the sample precisely matches the set pressure curve. During the in-situ mechanical testing phase, the engine is responsible for precisely controlling the pulse frequency and number of the stepper motor in the in-situ microenvironment mechanical loading module 30 to achieve a highly constant peeling or shearing rate.

[0065] The data analysis and report generator can automatically batch process the massive amounts of raw data recorded by the data synchronization acquisition unit 45 after a complete test sequence. Its built-in algorithm can automatically identify stable regions in the stripping process and calculate and extract a series of key performance indicators.

[0066] For example: average peel strength (N / 25mm), peak peel force, minimum peel force, peel force fluctuation coefficient, adhesive energy (obtained by integrating the force-displacement curve), lap shear strength at different temperatures, creep strain variation curve over time, etc.

[0067] It should be noted that this software can perform time-axis alignment and correlation analysis between force-displacement curves and temperature curves, pressure curves, and interfacial pressure distribution cloud maps during the hot pressing process, presenting the data intuitively in the form of 3D or 4D charts. This reveals the intrinsic influence of minute fluctuations in bonding process parameters (such as heating rate and uniformity of holding pressure) on the final bonding performance (such as the dispersion of peel strength). This provides unprecedented quantitative data support with profound physical significance for the rapid screening of new adhesive tape materials, the scientific optimization of production process windows, and the analysis of occasional bonding failures.

[0068] A complete workflow of the detection system of this invention is as follows: Figure 7 As shown, the specific steps are as follows:

[0069] The first step is sample preparation and installation. The operator precisely attaches the hot melt double-sided adhesive tape 100 to be tested between the lower rigid substrate 101 (exemplarily, a 6061 aluminum alloy plate, simulating the battery cell casing) and the upper flexible substrate 102 (exemplarily, a 50-micron-thick polyimide film), and places the assembly on the lower pressure head base 12, and reliably fixes it by the electromagnetic chuck array 16.

[0070] The second step is parameter setting. The operator loads a specific hot-press bonding process curve from the database or edits it online through the software interface of the central process control and data processing unit 50 (for example, simulating the pressing station parameters of a specific battery pack production line), and sets one or more subsequent in-situ test environment temperature points (for example, -20℃, 25℃, 85℃).

[0071] The third step is to start the fully automatic test sequence. After the operator clicks the start test button, the system enters the fully automatic operation mode: the door of the environmental simulation and isolation chamber 20 automatically closes and locks, the vacuum pump starts to evacuate the inside of the chamber to the preset vacuum level, and then fills it with high-purity dry nitrogen to a slightly positive pressure state.

[0072] The fourth step is dynamic thermal bonding. The upper pressure head assembly 11 of the dynamic thermal bonding module 10 automatically descends, contacts the sample, switches to force control mode, and strictly follows the temperature-pressure-time curve set in the second step to complete the dynamic bonding process of the sample. During this process, all sensors of the multi-physics coupling sensing and acquisition module 40 work continuously, recording various process parameters in real time.

[0073] Step 5: Ambient temperature control. After the bonding process is completed, the upper pressure head assembly 11 automatically lifts up and detaches from the sample. At this time, the air temperature control system 22 in the environmental simulation and isolation chamber 20 starts working, quickly adjusting the ambient temperature inside the chamber to the preset first test temperature point (exemplarily 85°C) and waiting for the temperature field inside the chamber to reach a stable state (typically, the temperature drift is less than 0.1°C / minute).

[0074] Step 6: In-situ mechanical testing. After the sample and ambient temperature reach thermal equilibrium, the in-situ microenvironment mechanical loading module 30 automatically starts. The flexible substrate clamping and force measuring component 32 clamps the free end of the flexible substrate 102 and performs a peeling or shearing test at a set constant rate. At the same time, the force sensor 34 and displacement sensor 44 record complete mechanical response data.

[0075] Step 7: Loop Testing and Termination. If multiple test temperature points are set, the system will automatically adjust the ambient temperature to the next temperature point after completing the test at one point, and repeat step 6. After all test points are completed, the system returns to its initial state.

[0076] Step 8: Data Processing and Report Generation. After the test, the measurement, control, and analysis software 52 automatically processes the data, calculates various performance indicators, and integrates the process data and result data to generate a detailed PDF test report containing charts and key parameters.

[0077] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A performance testing system for hot melt double-sided adhesive tape used in lithium battery modules, characterized in that, include: The dynamic hot-press bonding module (10) is configured to apply programmable temperature and pressure to a rigid substrate and a flexible substrate holding the tape sample to be tested. An environmental simulation and isolation cavity (20) is a sealed container. Part of the structure of the dynamic hot-press bonding module (10) and the following in-situ micro-environment mechanical loading module (30) are disposed inside the environmental simulation and isolation cavity (20). The environmental simulation and isolation cavity (20) is configured to establish a programmable wide temperature range environment inside it. The in-situ microenvironment mechanical loading module (30) is set inside the environment simulation and isolation cavity (20) and is configured to apply mechanical load to the tape sample to be tested in a specific temperature field environment created inside the environment simulation and isolation cavity (20) after the dynamic hot-press bonding module (10) completes the bonding of the tape sample to be tested. The multi-physics coupling transmission and acquisition module (40) includes multiple sensors deployed inside the environmental simulation and isolation cavity (20) and on related components, and is configured to monitor and acquire multiple physical quantities, including temperature, pressure, force and displacement, in real time throughout the entire process of dynamic hot-press bonding and in-situ mechanical performance testing. The central process control and data processing unit (50), which is electrically connected to the dynamic hot-press bonding module (10), the environmental simulation and isolation cavity (20), the in-situ micro-environment mechanical loading module (30) and the multi-physics field coupling sensing and acquisition module (40), is configured to automatically control the testing process of the entire system and synchronously process and analyze the acquired data. The dynamic hot-press bonding module (10) includes an upper pressure head assembly (11) and a lower pressure head base (12). The upper pressure head assembly (11) and the lower pressure head base (12) are arranged opposite each other in the vertical direction, and together they form an action area for applying heat and pressure to the tape sample to be tested and the rigid substrate and the flexible substrate. The upper pressure head assembly (11) is fixed to the end of the output shaft of a high-precision electric cylinder (15) driven by an AC servo motor. The high-precision electric cylinder (15) has a built-in ball screw transmission mechanism and a torque sensor. The central process control and data processing unit (50) drives the upper pressure head assembly (11) to generate vertical lifting motion and apply a precise pressing force to the tape sample to be tested by performing force closed-loop control on the AC servo motor. The lower pressure head base (12) is fixedly installed on the bottom plate of the environmental simulation and isolation cavity (20), and its surface is integrated with an electromagnetic chuck array (16) for fixing the lower rigid substrate. The in-situ microenvironment mechanical loading module (30) includes a horizontally set precision linear moving platform (31) and a flexible substrate clamping and force measuring component (32). The precision linear moving platform (31) is composed of a stepper motor driving a ball screw through a coupling. The entire platform is installed on one side of the inner wall of the environmental simulation and isolation cavity (20). The flexible substrate clamping and force measuring component (32) is fixed to the slider of the precision linear moving platform (31). The component (32) is composed of a pneumatic wedge clamp (33) and an S-shaped high-precision force sensor (34) connected in series. The pneumatic wedge clamp (33) is used to clamp the flexible substrate in the substrate. The S-shaped high-precision force sensor (34) is used to measure the force value in real time during the mechanical performance test.

2. The performance testing system for hot melt double-sided adhesive tape for lithium battery modules according to claim 1, characterized in that, The core components of the upper pressure head assembly (11) and the lower pressure head base (12) are both hot pressing platforms (13). The hot pressing platform (13) is made of dispersion-strengthened oxygen-free copper and has an electrically insulating and wear-resistant layer formed on its surface. Inside the hot pressing platform (13), a matrix-arranged microfluidic network (14) is integrally processed. The microfluidic network (14) is connected to an external dynamic temperature control unit through a flexible pipeline resistant to high and low temperatures. The dynamic temperature control unit includes a refrigeration unit and a circulating heater. It is configured to achieve rapid programmed heating and cooling of the hot pressing platform (13) by regulating the temperature and flow rate of the heat-conducting medium flowing through the microfluidic network (14).

3. The performance testing system for hot melt double-sided adhesive tape for lithium battery modules according to claim 1, characterized in that, The environmental simulation and isolation cavity (20) is a double-walled structure. The space between its inner and outer walls is evacuated and filled with aerogel insulation material, and the surface of its inner wall is electrolytically polished. The environmental simulation and isolation cavity (20) is also equipped with an independent air temperature regulation system (22). The system includes a high-temperature centrifugal fan, a set of electric heating elements and a set of heat exchangers supplied by an external cold source. The centrifugal fan drives the gas in the environmental simulation and isolation cavity (20) to form a forced convection circulation, and the temperature is regulated by the electric heating elements or heat exchangers, thereby establishing the wide temperature range environment inside the environmental simulation and isolation cavity (20).

4. The performance testing system for hot melt double-sided adhesive tape for lithium battery modules according to claim 1, characterized in that, The in-situ microenvironment mechanical loading module (30) also includes a replaceable adapter installed between the precision linear moving platform (31) and the pressure head base (12). The adapter includes a shear test fixture for in-situ measurement of the overlap shear strength of the tape sample, or a creep test fixture for long-term monitoring of the creep displacement of the tape under specific temperature and constant load.

5. The performance testing system for hot melt double-sided adhesive tape for lithium battery modules according to claim 4, characterized in that, The multiphysics coupled sensing and acquisition module (40) includes: An interface temperature sensing unit is configured to measure the temperature of the bonding interface between the tape sample to be tested and the rigid and flexible substrates during hot-press bonding. The interface pressure distribution transmission unit is a flexible pressure distribution film sensor (43) that can be placed between the rigid substrate and the pressure head base (12), and is configured to measure and display the pressure distribution status of the entire bonding area in real time during the hot pressing process; The displacement sensing unit, which includes a laser displacement sensor (44) for measuring peel displacement or a linear variable differential transmitter for measuring creep displacement, is configured to record displacement in real time during the mechanical performance test. The data synchronization acquisition unit (45) is a data acquisition system based on the PXI bus architecture. It is configured to synchronously acquire all signals from the above-mentioned sensing units at a high sampling rate and assign a unified timestamp to all data points.

6. The performance testing system for hot melt double-sided adhesive tape for lithium battery modules according to claim 5, characterized in that, The interface temperature sensing unit includes at least two different types of temperature sensors: One is a non-contact infrared thermometer (41), whose probe focuses on the edge of the bonding interface between the adhesive tape sample to be tested and the rigid substrate and the flexible substrate through the calcium fluoride observation window (24) set on the top of the environmental simulation and isolation cavity (20), for non-contact direct measurement of the true temperature of the adhesive. Secondly, there is at least one armored K-type miniature thermocouple (42), which is pre-embedded inside the rigid substrate and the flexible substrate, and its measuring tip is adjacent to the bonding surface, for accurately measuring the temperature of the substrate near the bonding interface.

7. The performance testing system for hot melt double-sided adhesive tape for lithium battery modules according to claim 6, characterized in that, When the central process control and data processing unit performs temperature control on the dynamic hot-press bonding module (10), it is configured to execute a cascaded PID control strategy. The cascaded PID control strategy consists of an outer loop PID controller and an inner loop PID controller. The outer loop PID controller uses the actual temperature of the adhesive measured by the non-contact infrared thermometer (41) as the process variable, and its output value is used as the set point of the inner loop PID controller. The inner loop PID controller uses the temperature measured by the temperature sensor embedded in the hot-press platform (13) as its process variable. By adjusting the dynamic temperature control unit, it accurately tracks the dynamic set point output by the outer loop PID controller, thereby achieving precise closed-loop control of the actual temperature of the bonding interface.

Images