A hot embossing apparatus for a multilayer microfluidic chip

Abstract

This invention relates to the field of hot embossing equipment technology, and more particularly to a hot embossing device for multilayer microfluidic chips. The device includes a transport mechanism, a feeding mechanism, a rolling mechanism, a vacuum chamber assembly, a temperature sensing assembly, a pressure sensing assembly, and a data processing module. The data processing module adjusts the conveyor belt speed based on the temperature change curve of the initially injected raw material within the substrate assembly, and adjusts the temperature of the die roller assembly based on the maximum thickness deviation between the thickest and thinnest positions of the sheet after rolling. A feedback adjustment module determines the rolling uniformity of the planar roller assembly based on the temperature of the raw material and the normal pressure distribution on the substrate surface during pre-pressing, and adjusts the rolling pressure of the die roller assembly in conjunction with the pre-pressed single-layer chip. It also adjusts the vacuum processing parameters or vacuum processing method based on the degree of internal structural defects in the single-layer chip structure. This invention effectively improves the structural integrity of the single-layer chip by dynamically adjusting its processing parameters.

Description

Technical Field

[0001] This invention relates to the field of thermal embossing equipment technology, and more particularly to a thermal embossing equipment for multilayer microfluidic chips. Background Technology

[0002] In the thermal embossing fabrication process of multilayer microfluidic chips, the molding quality of a single layer directly determines the channel accuracy, bonding strength, and overall functional reliability of the stacked multilayers. However, the thermal embossing process is significantly affected by the coupling effects of multiple physical fields: the combined interference of factors such as raw material injection volume deviation, substrate flatness error, and roller parallelism drift results in unpredictable systematic deviations between the actual thickness distribution of the pre-pressed sheet and the theoretical set value. Traditional thermal embossing equipment typically relies solely on open-loop pressure control and empirical temperature settings, making it difficult to capture the true molding response under the aforementioned multi-source interference coupling of thermo-mechanical-rheological factors. Furthermore, existing processes lack a detection and compensation mechanism that links the pre-pressing quality with the preceding process parameters in a closed-loop control, leading to frequent defects such as single-layer chip channel structure collapse, accumulated interlayer thickness deviations, and internal bubble residue. Therefore, existing thermal embossing equipment still suffers from significant shortcomings, relying on destructive peel testing for process status assessment and lacking online non-destructive monitoring methods, making it difficult to meet the multiple fabrication requirements of multilayer microfluidic chips for single-layer structure thickness consistency, surface flatness, and internal structural integrity.

[0003] Chinese Patent Publication No. CN119840140A discloses a hot-pressing method for microfluidic chips and a microfluidic chip. The hot-pressing method for microfluidic chips includes the following steps: mold making, preparing a molding die, the molding die including: preparing a female mold and a male mold, at least two male molds are prepared, and the heights of the at least two male molds are different; detachably connecting the female mold to one of the male molds; heating, pressing the male mold against the blank, and heating the blank, the male mold, and the female mold; hot pressing, creating thermal pressure between the male mold and the blank, so that the male mold squeezes the blank, and the blank replicates the shape of the male mold, so as to process the blank into a microfluidic chip; demolding, cooling the microfluidic chip, the female mold, and the male mold, and separating the microfluidic chip and the male mold.

[0004] The following problems still exist in the existing technology: The inability to determine the uniformity of the rolling pressure of the planar roller group based on the temperature of the raw material and the normal force distribution on the base surface during the pre-pressing process, in order to adjust the rolling pressure of the mold roller group, resulted in the inability to dynamically adjust the processing parameters of the single-layer chip, leading to low structural integrity of the single-layer chip. Summary of the Invention

[0005] To address this issue, the present invention provides a hot stamping apparatus for multilayer microfluidic chips, which overcomes the problem in the prior art that the uniformity of the roll pressure of the planar roller group cannot be determined based on the temperature of the raw material and the normal force distribution on the substrate surface during the pre-pressing process, so as to adjust the roll pressure of the mold roller group, resulting in the inability to dynamically adjust the processing parameters of the single-layer chip and thus causing the structural integrity of the single-layer chip to be low.

[0006] To achieve the above objectives, the present invention provides a thermal embossing apparatus for multilayer microfluidic chips, comprising: A transport mechanism used to move the base assembly to the hot pressing position via a conveyor belt; A feeding mechanism is disposed above the transport mechanism for injecting a predetermined volume of chip material into the base assembly; The rolling mechanism, which is disposed above the conveyor belt, includes a set of planar rollers for pre-pressing the chip raw material, and a set of mold rollers for microchannel rolling of the pre-pressed sheet. A vacuum chamber assembly is disposed between the roller pressing mechanism and the transport mechanism, and is used to perform vacuum treatment on the entire base assembly carrying the pre-pressed sheet after the planar roller group has completed the pre-pressing. A temperature sensing component, which is connected to the feeding mechanism and the roller pressing mechanism, is used to acquire the temperature of the raw material during the pre-pressing process and the initial temperature at the time of injection in real time. A pressure sensing component, comprising a pressure sensing array connected to the roller pressing mechanism, for acquiring in real time the normal pressure distribution value applied to the surface of the base component during the pre-pressing process; The data processing module is used to adjust the conveying speed of the conveyor belt based on the temperature change curve of the raw material initially injected into the base assembly, and to adjust the temperature of the mold roller group based on the maximum deviation of the thickness of the sheet at the thickest and thinnest positions after rolling. The feedback adjustment module is used to determine the uniformity of the roll pressure of the planar roller group based on the temperature of the raw material and the normal pressure distribution on the base surface during the pre-pressing process, so as to adjust the roll pressure of the mold roller group in conjunction with the pre-pressed single-layer chip, and adjust the vacuum processing parameters or vacuum processing method based on the degree of internal structural defects of the single-layer chip structure.

[0007] Furthermore, the data processing module estimates the cooling time based on the preset volume of chip raw material and the target cooling temperature, and determines the cooling speed deviation based on the temperature change curve of the initially injected raw material in the base assembly within the cooling time, so as to adjust the conveying speed of the conveyor belt.

[0008] Furthermore, the data processing module determines the rolling efficiency based on the maximum deviation between the thickness of the thickest and thinnest positions of the sheet after rolling, and determines whether to adjust the temperature of the mold roller group based on the rolling efficiency and the temperature change during the pre-pressing process of the planar roller group.

[0009] Furthermore, the feedback adjustment module determines the heat-affected zone based on the surface temperature distribution of the raw material before and after pre-compression, and determines the expansion rate based on the temperature change curve of the heat-affected zone during the pre-compression process.

[0010] Furthermore, the feedback adjustment module determines the stress concentration direction based on several normal forces detected by the pressure sensor array on the base surface during the pre-compression process, and combines these normal forces to determine the normal force distribution range.

[0011] Furthermore, the feedback adjustment module determines the roll pressure uniformity of the planar roll group based on the normal force distribution range and the expansion change rate; If the normal force distribution range is greater than the preset range, or the expansion rate is greater than the preset expansion rate, the uniformity of the roll pressure of the planar roll group is determined to be unqualified.

[0012] Furthermore, the feedback adjustment module determines that the uniformity of the roll pressure of the planar roll group is qualified based on the fact that the normal force distribution range is less than or equal to the preset range and the expansion change rate is less than or equal to the preset expansion change rate.

[0013] Furthermore, the feedback adjustment module adjusts the rolling pressure of the mold roller group based on the judgment result of the non-compliance of the rolling pressure uniformity of the planar roller group and the thickness deviation distribution of the single-layer chip after pre-pressing.

[0014] Furthermore, the feedback adjustment module determines the degree of internal structural defects based on the volume of bubbles in the internal structure of the single-layer chip; If the internal structural defects are minor, the vacuum treatment parameters should be adjusted.

[0015] Furthermore, the feedback adjustment module adjusts the vacuum processing method based on the determination that the degree of internal structural defects of the single-layer chip is severe, combined with the morphology of the internal structural defects.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: By setting the feeding mechanism above the transport mechanism and configuring a preset volume injection function, the present invention achieves quantitative control of the chip material injection amount, effectively reducing the probability of uneven thickness of the pre-pressed sheet caused by the volume deviation of manual glue injection; by integrating the planar roller group and the mold roller group on the same conveyor line, the present invention achieves continuous production of sheet pre-pressing and microchannel roller pressing, effectively overcoming the positioning deviation and surface contamination problems introduced by sheet transfer in traditional segmented processing; by setting a vacuum cavity assembly between the planar roller group and the mold roller group, the present invention achieves static vacuum degassing treatment of the pre-pressed sheet before entering the microstructure imprinting, effectively eliminating residual microbubbles that are difficult to remove by normal pressure roller pressing, and significantly reducing the thickness of the pre-pressed sheet. The system reduces the void defect rate inside the single-layer chip. By acquiring the initial temperature of the raw material injection and the temperature change during the pre-pressing process in real time through temperature sensing components, it achieves full-process thermal history tracking of the rheological state of the raw material, effectively solving the problem of processing window offset caused by viscosity fluctuations of temperature-sensitive materials. By acquiring the normal pressure distribution value of the base surface in real time through pressure sensing array, it effectively overcomes the limitations of traditional processes that rely on experience, visual inspection, or offline sampling to quantitatively evaluate the uniformity of rolling. By dynamically adjusting the conveyor belt speed through the data processing module, it effectively avoids channel replication defects. By determining the uniformity of rolling of the planar roller group through the feedback adjustment module and adjusting the roller pressure of the mold roller group, it achieves closed-loop iterative optimization of pre-pressing and mold imprinting, thereby significantly improving the structural integrity of the single-layer chip.

[0017] Furthermore, this invention determines the target thickness by using the ratio of preset volume to effective area and the expected cooling time by using the difference between the initial temperature and the target temperature, thus achieving accurate prediction of the timing parameters of the chip material cooling process. It determines the cooling rate deviation based on the difference between the predicted cooling rate and the actual cooling rate, accurately identifying the degree of process deviation in the material cooling process during the pre-pressing stage. This balances the sensitivity of conveying rate adjustment with the stability of system operation. It determines whether to adjust the temperature of the mold roller group based on the cross-logic of roller pressing efficiency and pre-pressing temperature difference, providing a dynamic decision-making basis for the thermodynamic parameters of the mold roller group. Based on the differential analysis of the surface temperature distribution of the material before and after pre-pressing, it determines the heat-affected zone and the rate of expansion change, achieving spatial positioning and dynamic quantitative evaluation of thermally induced non-uniformity in the pre-pressing process. This quantitatively reflects the local stress accumulation trend caused by the difference in thermal expansion inside the material, thereby significantly improving the structural integrity of the single-layer chip.

[0018] Furthermore, this invention determines the reference value of normal force by the average of several normal forces during the pre-pressing process, and uses this to identify the stress concentration direction and the range of normal force distribution. This achieves accurate perception and quantitative characterization of the spatial distribution characteristics of the force field on the base surface. The roll pressing uniformity of the planar roller group is determined by the dual criteria of the range of normal force distribution and the rate of expansion change. This enables the cross-correlation assessment of mechanical non-uniformity and thermal non-uniformity in the pre-pressing process, effectively improving the sensitivity of identifying static force field distribution deviation and the early warning timeliness of dynamic thermal expansion behavior. It provides a clear physical threshold for the standardized judgment of roll pressing uniformity, avoiding the confusion between normal process fluctuations and real defects. Based on the spatial positioning and quantification of the stress concentration direction and the range of normal force distribution, it provides a mechanical tracing basis for determining the pressure compensation direction of the subsequent mold roller group, quantitatively reflecting the causal transmission relationship between pre-pressing field defects and sheet thickness deviation, thereby significantly improving the structural integrity of the single-layer chip.

[0019] Furthermore, this invention determines the pressure compensation direction by comparing the thickness deviation in the stress concentration direction with the average thickness deviation, thus achieving spatial positioning of pre-pressed sheet thickness defects and vector orientation compensation of mold roller pressure. Based on the quantitative comparison of bubble volume with a preset bubble volume threshold, the degree of internal structural defects is determined, accurately distinguishing between process-acceptable micro-nano bubbles and critical defects that lead to functional failure. Based on the morphological characteristics under severe defects, the vacuum treatment method is adjusted, realizing a strategy upgrade from physical degassing to chemical inert protection. Based on the morphological characteristics of interlayer delamination or bulging, the vacuum treatment method is adjusted to pulsed vacuuming, providing adaptive process assurance for the filling integrity, interlayer bonding strength, and internal density of microchannel imprinting. It realizes closed-loop feedback decision-making from defect identification, defect classification to targeted control of defect morphology, quantitatively reflecting the causal compensation relationship between pre-pressing defects and mold roller pressure and vacuum treatment parameters, effectively improving the yield stability and internal quality of chip hot pressing process under complex disturbances, thereby significantly improving the structural integrity of single-layer chips. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a thermal embossing device for multilayer microfluidic chips according to an embodiment of the present invention; Figure 2 This is a module connection diagram of a thermal embossing device for multilayer microfluidic chips according to an embodiment of the present invention; Figure 3 A logic diagram for determining whether to adjust the temperature of the mold roller assembly in an embodiment of the present invention; Figure 4 A logic diagram for determining the uniformity of roll pressure of a planar roll group in an embodiment of the present invention; Among them, 1 is the transportation mechanism; 11 is the conveyor belt; 12 is the base assembly; 2 is the feeding mechanism; 3 is the rolling mechanism; 31 is the flat roller group; 32 is the mold roller group; and 4 is the vacuum chamber assembly. Detailed Implementation

[0021] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0022] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0023] It should be noted that in the description of this invention, the terms such as up, down, left, right, inside, and outside indicate the direction or positional relationship based on the direction or positional relationship shown in the drawings. This is only for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0024] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms installation, connection, and linking should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0025] Please see Figure 1 The diagram shown is a schematic of a thermal embossing apparatus for multilayer microfluidic chips according to an embodiment of the present invention. The thermal embossing apparatus for multilayer microfluidic chips according to an embodiment of the present invention includes: The transport mechanism 1 is used to transport the base assembly 12 to the hot pressing position via the conveyor belt 11; wherein the base assembly 12 is a mold used for forming a chip into a thin sheet structure. The feeding mechanism 2 is located above the transport mechanism 1 and is used to inject a preset volume of chip material into the base assembly 12. The roller pressing mechanism 3 is disposed above the conveyor belt 11 and includes a planar roller group 31 for pre-pressing the chip raw material and a mold roller group 32 for microchannel roller pressing the pre-pressed sheet. The vacuum chamber assembly 4 is located between the roller pressing mechanism 3 and the transport mechanism 1, and is used to perform vacuum treatment on the base assembly 12 carrying the pre-pressed sheet after the planar roller group 31 has completed the pre-pressing. The temperature sensing component is connected to the feeding mechanism 2 and the roller pressing mechanism 3 to obtain the temperature of the raw material during the pre-pressing process and the initial temperature at the time of injection in real time. The pressure sensing component includes a pressure sensing array connected to the roller pressing mechanism 3, for real-time acquisition of the normal pressure distribution value applied to the surface of the base assembly 12 during the pre-pressing process; The data processing module is used to adjust the conveying speed of the conveyor belt 11 based on the temperature change curve of the raw material initially injected into the base assembly 12, and to adjust the temperature of the mold roller group 32 based on the maximum deviation of the thickness of the thickest and thinnest positions of the sheet after rolling. The feedback adjustment module is used to determine the rolling pressure uniformity of the planar roller group 31 based on the temperature of the raw material and the normal pressure distribution on the base surface during the pre-pressing process, so as to adjust the rolling pressure of the mold roller group 32 in conjunction with the pre-pressed single-layer chip, and adjust the vacuum processing parameters or vacuum processing method based on the degree of internal structural defects of the single-layer chip structure.

[0026] It is understandable that chip raw materials can be polysiloxane materials or other thermoplastic materials.

[0027] Specifically, before producing a single-layer chip, the base assembly 12 is first cleaned and its flatness is checked. After confirming that the base assembly 12 is of qualified quality, it is placed on the conveyor belt 11. According to the hot pressing process rhythm, the transport mechanism 1 transports the base assembly 12 to the hot pressing position through the conveyor belt 11. The feeding mechanism 2 is set above the transport mechanism 1 and injects a preset volume of chip raw material into the base assembly 12. The rolling mechanism 3 is set above the conveyor belt 11 and uses a flat roller group 31 to pre-press the chip raw material to form a pre-pressed sheet. The vacuum chamber assembly 4 is set between the rolling mechanism 3 and the transport mechanism 1. After the flat roller group 31 completes the pre-pressing, the base assembly 12 carrying the pre-pressed sheet is transported as a whole to the vacuum chamber assembly 4 for vacuum treatment. The mold roller group 32 then performs microchannel rolling on the vacuum-treated pre-pressed sheet to obtain a single-layer chip with a microchannel structure.

[0028] Please see Figure 2 As shown, it is a module connection diagram of a thermal embossing device for multilayer microfluidic chips according to an embodiment of the present invention. The data processing module estimates the cooling time based on the preset volume of chip raw material and the target cooling temperature, and determines the cooling speed deviation based on the temperature change curve of the initially injected raw material in the base assembly within the cooling time, so as to adjust the conveying speed of the conveyor belt.

[0029] Specifically, the data processing module includes: The cooling time determination unit is used to determine the target thickness based on the ratio of the preset volume to the effective area of ​​the base component, determine the expected cooling time based on the difference between the initial temperature and the target temperature, determine the time correction factor based on the ratio of the target thickness to the standard thickness, and determine the estimated cooling time based on the product of the time correction factor and the expected cooling time. Specifically, the effective area of ​​the base assembly refers to the area of ​​the molding plane of the layered sheet structure of the mold. The target thickness is determined based on the ratio of the preset volume to the effective area. The initial temperature refers to the material temperature when the preset volume of chip material is injected. The target temperature is the material temperature when the cooled chip material is effectively pre-pressed. The estimated cooling time is determined based on the difference between the initial temperature and the target temperature and the reference heat exchange efficiency of the chip material. The standard thickness is the design thickness of the mold. The reference heat exchange efficiency is the average rate of temperature change of the chip material in the base assembly at the initial temperature under constant ambient temperature conditions. The ambient temperature is set to the operating ambient temperature to ensure the accuracy of the measured reference heat exchange efficiency. In this embodiment, the estimated cooling time is used to quantify the time required for the temperature change of the chip material.

[0030] The cooling rate deviation determination unit is used to determine the cooling temperature difference based on the difference between the initial temperature and the target temperature, and to determine the estimated cooling rate based on the ratio of the cooling temperature difference to the estimated cooling time. In this embodiment, a temperature change curve of the raw material is established with time as the horizontal axis and the temperature measurement value of the chip raw material as the vertical axis, and the slope of the temperature change curve is determined to be the actual cooling rate. The cooling speed deviation is determined based on the absolute value of the difference between the predicted cooling speed and the actual cooling speed, and the conveying speed of the conveyor belt is adjusted based on the comparison result between the cooling speed deviation and the deviation threshold.

[0031] Specifically, the cooling speed deviation determination unit determines not to adjust the conveying speed of the conveyor belt in response to the cooling speed deviation being less than the deviation threshold. In response to a cooling rate deviation being greater than or equal to a deviation threshold, the conveying rate of the conveyor belt is adjusted. If the estimated cooling rate is greater than the actual cooling rate, the conveyor belt speed should be reduced. If the estimated cooling rate is less than the actual cooling rate, increase the conveyor belt's conveying speed.

[0032] Specifically, the reduced conveying rate is the product of the initial conveying rate and the rate reduction factor, while the increased conveying rate is the ratio of the initial conveying rate to the rate reduction factor.

[0033] The rate reduction factor is the ratio of the deviation threshold to the cooling rate deviation.

[0034] Specifically, the data processing module includes a deviation threshold determination unit, which determines the critical value for judging whether the cooling speed deviation exceeds the acceptable range based on the temperature-sensitive characteristics of the chip raw materials and the process tolerance requirements. The deviation threshold ensures the sensitivity and specificity of the conveyor belt speed adjustment judgment, while avoiding system oscillation caused by frequent start-stop speed adjustment, or missing the judgment of cooling abnormalities. This prevents the microchannel imprinting depth deviation and sheet density difference caused by uneven curing degree of raw materials in the pre-pressing stage, and realizes the standardization of cooling process deviation judgment.

[0035] Specifically, the data processing module determines the rolling efficiency based on the maximum deviation between the thickness of the thickest and thinnest parts of the sheet after rolling, and adjusts the temperature of the mold roller group based on the rolling efficiency and the temperature change during the pre-pressing process of the planar roller group.

[0036] Specifically, the data processing module includes a roll forming efficiency determination unit, which is used to determine the roll forming efficiency based on the maximum deviation of the thickness between the thickest and thinnest positions of the sheet after roll forming. In this embodiment, the baseline deviation is determined based on the difference between the thickest position of the rolled sheet and the standard thickness, and the maximum deviation is determined based on the difference between the thickness of the thickest position and the thinnest position of the rolled sheet. A maximum deviation greater than the reference deviation is considered high rolling efficiency; a maximum deviation less than or equal to the reference deviation is considered low rolling efficiency.

[0037] Specifically, the data processing module includes a mold roller group temperature adjustment and determination unit, which is used to determine the pre-pressing temperature difference based on the difference between the surface temperature of the planar roller group after pre-pressing and the surface temperature before pre-pressing. Please see Figure 3 As shown, this is a logic diagram for determining whether to adjust the temperature of the mold roller group in an embodiment of the present invention. If the rolling efficiency is high and the pre-pressing temperature difference is less than the cooling temperature difference, the temperature of the mold roller group is increased. If the rolling efficiency is low and the pre-pressing temperature difference is greater than the cooling temperature difference, the temperature of the mold roller group is decreased. When neither of the above two conditions is met, the current temperature of the mold roller group is maintained.

[0038] In this embodiment, the rolling efficiency reflects the degree of non-uniform deformation of the raw material during the pre-compression stage, and the pre-compression temperature difference reflects the level of self-heating generated by the material due to viscous dissipation. When the rolling efficiency is high and the pre-compression temperature difference is less than the cooling temperature difference, it indicates that the mechanical work is sufficient and the macroscopic deformation is severe, but the material temperature rise is insufficient. That is, the raw material is in a state of high elasticity and low relaxation, which is prone to causing the flow channel sidewall to rebound and collapse. Therefore, active heating accelerates the thermal motion of molecular chains, shortens the relaxation time, and releases elastic stored energy to improve its flowability and filling properties. When the rolling efficiency is low and the pre-pressing temperature difference is greater than the cooling temperature difference, it indicates that the mechanical work is insufficient, but the material is abnormally heated. This means that the raw material is excessively softened due to excessively high initial temperature or heat accumulation, and the transmission of friction is hindered. Therefore, the temperature of the mold roller group should be reduced and the rigidity of the raw material should be appropriately increased to restore its ability to resist excessive deformation. When neither of these conditions is met, it indicates that the process is in a relatively balanced state, and the current parameters should be maintained.

[0039] Specifically, the feedback adjustment module determines the heat-affected zone based on the surface temperature distribution of the raw material before and after pre-compression, and determines the expansion rate based on the temperature change curve of the heat-affected zone during the pre-compression process.

[0040] Specifically, the feedback adjustment module includes: The heat-affected zone determination unit is used to determine the surface temperature before pre-compression based on the average value of several raw material surface temperatures detected by each pressure sensor detection area before pre-compression, to determine the surface temperature after pre-compression based on the average value of several raw material surface temperatures detected by each pressure sensor detection area after pre-compression, and to determine the temperature change reference value based on the difference between the surface temperature after pre-compression and the surface temperature before pre-compression. The heat-affected zone is determined based on the temperature change benchmark value and the temperature change difference before and after pre-compression in each detection area. Specifically, if the temperature change difference before and after pre-compression in the detection area is greater than the temperature change benchmark value, the area is determined to be a heat-affected zone; if the temperature change difference before and after pre-compression in the detection area is less than or equal to the temperature change benchmark value, the area is determined to be a non-heat-affected zone.

[0041] The expansion rate determination unit is used to establish the temperature change curve of the heat-affected zone based on the time of the heat-affected zone during the pre-compression process as the horizontal axis and the surface temperature at each moment during the pre-compression process as the vertical axis. The slope of the temperature change curve of the heat-affected zone is determined as the expansion rate. It can be understood that if there are multiple heat-affected zones, the expansion rate is the average of the slopes of the temperature change curves of each heat-affected zone.

[0042] Specifically, this invention determines the target thickness by setting the ratio of the preset volume to the effective area, and determines the expected cooling time by setting the difference between the initial temperature and the target temperature. This achieves accurate prediction of the timing parameters of the chip material cooling process. Based on the difference between the predicted cooling rate and the actual cooling rate, the cooling rate deviation is determined, accurately identifying the degree of process deviation in the material cooling process during the pre-pressing stage. It takes into account both the sensitivity of the conveying rate adjustment and the stability of the system operation. Based on the cross logic of the rolling efficiency and the pre-pressing temperature difference, it determines whether to adjust the temperature of the mold roller group, providing a dynamic decision basis for the thermodynamic parameters of the mold roller group. Based on the differential analysis of the surface temperature distribution of the material before and after pre-pressing, it determines the heat-affected area and its rate, realizing the spatial positioning and dynamic quantitative evaluation of thermally induced non-uniformity in the pre-pressing process. It quantitatively reflects the local stress accumulation trend caused by the difference in thermal expansion inside the material, thereby significantly improving the structural integrity of the single-layer chip.

[0043] Specifically, the feedback adjustment module determines the stress concentration direction based on several normal forces detected by the pressure sensor array on the base surface during the pre-compression process, and combines these normal forces to determine the normal force distribution range.

[0044] Specifically, the feedback adjustment module includes: The stress concentration direction determination unit is used to determine the normal force reference value based on the average value of several normal forces during the preloading process, and to determine the direction of change of the normal force greater than the normal force reference value from the center of the base surface to several normal forces as the stress concentration direction.

[0045] The normal force distribution range determination element is used to determine the normal force distribution range based on the difference between the maximum and minimum normal force values ​​in the stress concentration direction.

[0046] In this embodiment, the normal force is the reverse force of the chip material resisting compression, detected by the pressure sensor array when the rolling mechanism rolls the chip material in the base assembly during the pre-compression process.

[0047] Specifically, the feedback adjustment module determines the roll pressure uniformity of the planar roll group based on the normal force distribution range and the expansion change rate; Please see Figure 4 As shown, it is a logic judgment diagram for determining the roll pressure uniformity of the planar roller group in an embodiment of the present invention. If the normal force distribution range is greater than the preset range, or the expansion change rate is greater than the preset expansion change rate, the roll pressure uniformity of the planar roller group is determined to be unqualified; otherwise, the roll pressure uniformity of the planar roller group is determined to be qualified.

[0048] Specifically, the feedback adjustment module includes a preset range determination unit, which determines the preset range based on the stiffness coefficient of the planar roller group and the flatness tolerance of the base assembly, by calculating the theoretical pressure distribution range of the roller contact area using Hertzian contact theory. The preset range ensures that the mechanical benchmark for judging the uniformity of roller pressing has a clear physical upper limit, while avoiding normal process fluctuations from being misjudged as non-uniformity, sheet density gradient, or base deformation. This prevents systematic deviations in the thickness of the pre-pressed sheet and subsequent microchannel filling depth inconsistencies caused by uneven force fields, thus achieving the standardization and quantification of mechanical uniformity criteria.

[0049] Specifically, the feedback adjustment module includes a preset expansion rate determination unit, which uses the thermal expansion coefficient of the chip material and the maximum thermally induced volume change rate allowed by the process to deduce the theoretical upper limit of the expansion rate through thermoelastic constitutive relations, and determines the upper limit by taking the smaller of the two values ​​from the statistical upper limit of thermal experimental data under the standard process window. The preset expansion rate ensures the timeliness and accuracy of the determination of sheet expansion by temperature disturbance, while avoiding the misjudgment of instantaneous temperature rise caused by friction or ambient temperature as expansion abnormality, or non-steady-state volume expansion caused by exothermic curing reaction inside the material. This prevents sheet surface wrinkles, loss of microchannel preform surface accuracy and uneven filling of subsequent mold rolling caused by uncontrolled expansion rate, and realizes the standardization and early warning of thermal defect judgment criteria.

[0050] Specifically, the feedback adjustment module determines that the uniformity of the roll pressure of the planar roll group is qualified based on the fact that the normal distribution range is less than or equal to the preset range and the expansion change rate is less than or equal to the preset expansion change rate.

[0051] Specifically, this invention determines the reference value of normal force by averaging several normal forces during the pre-pressing process, and uses this to identify the stress concentration direction and the range of normal force distribution. This achieves accurate perception and quantitative characterization of the spatial distribution characteristics of the force field on the base surface. The roll pressing uniformity of the planar roller group is determined by the dual criteria of the range of normal force distribution and the rate of expansion change. This enables the cross-correlation assessment of mechanical non-uniformity and thermal non-uniformity in the pre-pressing process, effectively improving the sensitivity of identifying static force field distribution deviation and the early warning timeliness of dynamic thermal expansion behavior. It provides a clear physical threshold for the standardized judgment of roll pressing uniformity, avoiding misjudgment and confusion between normal process fluctuations and real defects. Based on the spatial positioning and quantification of the stress concentration direction and the range of normal force distribution, it provides a mechanical tracing basis for determining the pressure compensation direction of the subsequent mold roller group, quantitatively reflecting the causal transmission relationship between pre-pressing field defects and sheet thickness deviation, thereby significantly improving the structural integrity of the single-layer chip.

[0052] Specifically, the feedback adjustment module adjusts the roller pressure of the mold roller group based on the judgment result of the non-compliance of the roller pressure uniformity of the planar roller group and the thickness deviation distribution of the single-layer chip after pre-pressing.

[0053] Specifically, the feedback adjustment module includes: The thickness deviation distribution determination unit is used to determine the pressure compensation direction based on the thickness deviation of the pre-formed single-layer chip in the stress concentration direction and the average thickness deviation of the single-layer chip. In response to the thickness deviation being greater than or equal to the average thickness deviation in the stress concentration direction, it is determined that the pressure compensation direction is in the same direction as the stress concentration direction, that is, the roller pressure of the mold roller group is increased in this direction to compensate for the accumulation of raw materials. In response to the fact that the thickness deviation in the stress concentration direction is less than the average thickness deviation of a single-layer chip, it is determined that the pressure compensation direction is opposite to the stress concentration direction. That is, the roller pressure of the mold roller group is reduced in this direction to alleviate the sheet thinning caused by overpressure.

[0054] In this embodiment, when the uniformity of the roll pressure is unqualified due to mechanical or thermodynamic disturbances in the planar roller group, the pre-pressed single-layer chip sheet already has an irreversible thickness deviation distribution. At this time, the purpose of adjusting the roller pressure of the mold roller group is to: increase the roller pressure to make the microchannels in the material accumulation area fully filled, avoiding microchannel defects or insufficient depth caused by underpressure; and reduce the roller pressure to prevent base film deformation, chip breakage or microchannel collapse caused by overpressure in the thin material area, so as to ensure the depth consistency, filling integrity and low residual stress inside the chip of the microchannel structure, thereby improving the yield stability and adaptability of the system under process disturbances.

[0055] Specifically, the feedback adjustment module determines the degree of internal structural defects based on the volume of bubbles in the internal structure of a single-layer chip. If the internal structural defects are minor, the vacuum treatment parameters should be adjusted.

[0056] Specifically, the feedback adjustment module includes: An internal defect degree determination unit is used to determine the degree of internal structural defects based on the comparison result between the bubble volume in the internal structure of a single-layer chip and a preset bubble volume threshold. In response to the fact that the volume of bubbles in the internal structure of a single-layer chip is less than or equal to a preset bubble volume threshold, the vacuum processing parameters are adjusted, including extending the vacuum processing time or increasing the vacuum level, in order to enhance the degassing driving force and promote the escape and destruction of residual microbubbles. If the volume of bubbles in the internal structure of a single-layer chip exceeds a preset bubble volume threshold, the degree of internal structural defects in the single-layer chip is determined to be severe.

[0057] Specifically, the feedback adjustment module includes a preset bubble volume threshold determination unit, which determines the critical failure volume of bubbles based on the microchannel feature size and the chip functional layer design thickness. The median value of the internal bubble volume of the chip formed under standard process and the maximum allowable internal porosity after chip hot pressing are corrected by ultrasonic scanning microscope or X-ray non-destructive testing. The preset bubble volume threshold ensures the sensitivity and specificity of the internal structural defect determination, while avoiding the misjudgment of micro-nano level dissolved gas precipitation allowed by normal process as a defect, or critical bubbles of stress concentration or microchannel blockage. This prevents interlayer delamination after chip hot pressing, abnormal microchannel flow resistance, and bubble expansion and cracking in humid and hot environments during long-term service caused by bubble residue, thus achieving the standardization and quantification of internal bubble defect judgment.

[0058] Specifically, the feedback adjustment module adjusts the vacuum treatment method based on the severity of the internal structural defects of the single-layer chip and the morphology of the internal structural defects.

[0059] When the degree of internal structural defects of a single-layer chip is severe, if the internal structural defect morphology of the single-layer chip is rough inner wall of the flow channel or traces of oxidation and stickiness on the surface, the vacuuming process will be adjusted to a process of vacuuming followed by filling with inert gas. If the internal structural defects of a single-layer chip are interlayer delamination or bulging, the vacuuming process should be adjusted to a pulsed vacuuming process.

[0060] In this embodiment, when roughness or sticky oxidation of the inner wall of the flow channel is detected, it is determined that the cause is the interfacial chemical degradation between the raw material and residual oxygen and water vapor. Therefore, the process is adjusted to vacuuming and then filling with inert gas to block the oxidation reaction chain from the source through chemical passivation protection. When interlayer delamination or bulging is detected, it is determined that the interfacial barrier of deeply buried bubbles inside the high-viscosity raw material is difficult to overcome by steady-state negative pressure. Therefore, the process is adjusted to pulsed vacuuming to force bubble nucleation, aggregation and escape through alternating pressure field.

[0061] Specifically, this invention determines the pressure compensation direction by comparing the thickness deviation in the stress concentration direction with the average thickness deviation, thus achieving spatial positioning of pre-pressed sheet thickness defects and vector orientation compensation of mold roller pressure. Based on the quantitative comparison of bubble volume with a preset bubble volume threshold, the degree of internal structural defects is determined, accurately distinguishing between process-acceptable micro-nano bubbles and critical defects that lead to functional failure. Based on the morphological characteristics of severe defects, the vacuum treatment method is adjusted, realizing a strategy upgrade from physical degassing to chemical inert protection. Based on the morphological characteristics of interlayer delamination or bulging, the vacuum treatment method is adjusted to pulsed vacuuming, providing adaptive process assurance for the filling integrity, interlayer bonding strength, and internal density of microchannel imprinting. It realizes closed-loop feedback decision-making from defect identification, defect classification to targeted control of defect morphology, quantitatively reflecting the causal compensation relationship between pre-pressing defects and mold roller pressure and vacuum treatment parameters, effectively improving the yield stability and internal quality of chip hot pressing process under complex disturbances, thereby significantly improving the structural integrity of single-layer chips.

[0062] Specifically, this invention achieves quantitative control of chip material injection volume by placing the feeding mechanism above the transport mechanism and configuring a preset volume injection function. This effectively reduces the probability of uneven pre-pressed sheet thickness caused by manual dispensing volume deviation. By integrating the planar roller group and the mold roller group on the same conveyor line, continuous production of sheet pre-pressing and microchannel rolling is achieved, effectively overcoming the positioning deviation and surface contamination problems introduced by sheet transfer in traditional segmented processing. By setting a vacuum chamber assembly between the planar roller group and the mold roller group, static vacuum degassing treatment is achieved for the pre-pressed sheet before entering the microstructure imprinting process. This effectively eliminates residual microbubbles that are difficult to remove under normal pressure rolling, significantly reducing the thickness of single-layer chips. The void defect rate is controlled by real-time acquisition of the initial temperature of raw material injection and the temperature change during the pre-compression process through temperature sensing components, realizing full-process thermal history tracking of the rheological state of the raw material. This effectively solves the problem of processing window offset caused by viscosity fluctuations of temperature-sensitive materials. The normal pressure distribution value of the base surface is acquired in real time through pressure sensing array, which effectively overcomes the limitations of traditional processes that rely on experience, visual inspection or offline sampling to quantitatively evaluate the uniformity of roll pressing. The conveyor belt speed is dynamically adjusted through data processing module, which effectively avoids channel replication defects. The roll pressing uniformity of the planar roller group is determined through feedback adjustment module, and the roll pressure of the mold roller group is adjusted, realizing closed-loop iterative optimization of pre-compression forming and mold imprinting, thereby significantly improving the structural integrity of single-layer chips.

[0063] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A thermal embossing device for multilayer microfluidic chips, characterized in that, include: A transport mechanism used to move the base assembly to the hot pressing position via a conveyor belt; A feeding mechanism is disposed above the transport mechanism for injecting a predetermined volume of chip material into the base assembly; The rolling mechanism, which is disposed above the conveyor belt, includes a set of planar rollers for pre-pressing the chip raw material and a set of mold rollers for microchannel rolling of the pre-pressed sheet. A vacuum chamber assembly is disposed between the roller pressing mechanism and the transport mechanism, and is used to perform vacuum treatment on the entire base assembly carrying the pre-pressed sheet after the planar roller group has completed the pre-pressing. A temperature sensing component, which is connected to the feeding mechanism and the roller pressing mechanism, is used to acquire the temperature of the raw material during the pre-pressing process and the initial temperature at the time of injection in real time. A pressure sensing component, comprising a pressure sensing array connected to the roller pressing mechanism, for acquiring in real time the normal pressure distribution value applied to the surface of the base component during the pre-pressing process; The data processing module is used to adjust the conveying speed of the conveyor belt based on the temperature change curve of the raw material initially injected into the base assembly, and to adjust the temperature of the mold roller group based on the maximum deviation of the thickness of the sheet at the thickest and thinnest positions after rolling. The feedback adjustment module is used to determine the uniformity of the roll pressure of the planar roller group based on the temperature of the raw material and the normal pressure distribution on the base surface during the pre-pressing process, so as to adjust the roll pressure of the mold roller group in conjunction with the pre-pressed single-layer chip, and adjust the vacuum processing parameters or vacuum processing method based on the degree of internal structural defects of the single-layer chip structure.

2. The hot stamping apparatus for multilayer microfluidic chips according to claim 1, characterized in that, The data processing module estimates the cooling time based on the preset volume of chip raw material and the target cooling temperature, and determines the cooling speed deviation based on the temperature change curve of the initially injected raw material in the base assembly within the cooling time, so as to adjust the conveying speed of the conveyor belt.

3. The hot stamping apparatus for multilayer microfluidic chips according to claim 2, characterized in that, The data processing module determines the rolling efficiency based on the maximum deviation between the thickness of the thickest and thinnest positions of the sheet after rolling, and determines whether to adjust the temperature of the mold roller group based on the rolling efficiency and the temperature change during the pre-pressing process of the planar roller group.

4. The hot stamping apparatus for multilayer microfluidic chips according to claim 3, characterized in that, The feedback adjustment module determines the heat-affected zone based on the surface temperature distribution of the raw material before and after pre-compression, and determines the expansion rate based on the temperature change curve of the heat-affected zone during the pre-compression process.

5. The hot stamping apparatus for multilayer microfluidic chips according to claim 4, characterized in that, The feedback adjustment module determines the stress concentration direction based on several normal forces detected by the pressure sensor array on the base surface during the pre-compression process, and determines the normal force distribution range by combining several normal forces.

6. The hot stamping apparatus for multilayer microfluidic chips according to claim 5, characterized in that, The feedback adjustment module determines the roll pressure uniformity of the planar roll group based on the normal force distribution range and the expansion change rate. If the normal force distribution range is greater than the preset range, or the expansion rate is greater than the preset expansion rate, the uniformity of the roll pressure of the planar roll group is determined to be unqualified.

7. The hot stamping apparatus for multilayer microfluidic chips according to claim 6, characterized in that, The feedback adjustment module determines that the uniformity of the roll pressure of the planar roll group is qualified based on the fact that the normal distribution range is less than or equal to the preset range and the expansion change rate is less than or equal to the preset expansion change rate.

8. The hot stamping apparatus for multilayer microfluidic chips according to claim 7, characterized in that, The feedback adjustment module adjusts the rolling pressure of the mold roller group based on the judgment result of the non-compliance of the rolling pressure uniformity of the planar roller group and the thickness deviation distribution of the single-layer chip after pre-pressing.

9. The hot stamping apparatus for multilayer microfluidic chips according to claim 8, characterized in that, The feedback adjustment module determines the degree of internal structural defects based on the volume of bubbles in the internal structure of the single-layer chip. If the internal structural defects are minor, the vacuum treatment parameters should be adjusted.

10. The hot stamping apparatus for multilayer microfluidic chips according to claim 9, characterized in that, The feedback adjustment module adjusts the vacuum treatment method based on the determination that the internal structural defects of the single-layer chip are severe, combined with the morphology of the internal structural defects.

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