A method for optimizing a lamination and curing process of a multilayer flexible circuit board

Abstract

The present application relates to the technical field of circuit board production, in particular to a kind of multilayer flexible circuit board pressing and curing process optimization method.The present application obtains temperature stability according to the severity, duration and frequency of temperature value out of control of monitoring point in the temperature maintaining period, and obtains temperature stable uniformity by combining the uniformity of temperature value space distribution of monitoring point in the temperature maintaining period when temperature is normal, the change trend and space fluctuation degree of temperature out of control point when temperature is abnormal;According to the abnormal degree of temperature control of circuit board in the pressing cycle, temperature stable uniformity, and the temperature value drop quality of monitoring point in the cooling period, obtain pressing effect index, and optimize the pressing process of next pressing cycle by combining the quality of circuit board after pressing cycle.The present application optimizes pressing process by combining temperature control abnormal degree, temperature uniformity of temperature maintaining stage and cooling quality of cooling stage, improves the accuracy of pressing temperature control.

Description

Technical Field

[0001] This invention relates to the field of circuit board manufacturing technology, specifically to an optimized method for the lamination and curing process of multilayer flexible circuit boards. Background Technology

[0002] Multilayer flexible printed circuit boards (FPCBs) have become an indispensable core component in modern electronic devices due to their excellent electrical performance, high wiring density, and outstanding three-dimensional spatial adaptability. The lamination and curing processes in FPCB manufacturing are crucial steps in firmly bonding and curing multilayer conductive lines to the insulating substrate using adhesives, directly determining the structural integrity, electrical reliability, and long-term service life of the final product.

[0003] In the typical lamination process of circuit boards, segmented lamination is a critical step. Since the curing effect of adhesives is extremely sensitive to temperature fluctuations, the core of the lamination process lies in precise temperature control. Traditional PID temperature control strategies based on fixed parameters struggle to dynamically adapt to the complex thermal disturbances during lamination. When temperature fluctuations occur, the system's response lags due to parameter rigidity, resulting in coarse adjustments and causing the actual temperature to deviate significantly from the process window. This control inaccuracy directly leads to adhesive curing quality problems: if the temperature is too high, the adhesive may over-cur, causing the circuit board to become hard and brittle, with reduced flexibility; if the temperature is too low, the adhesive will not cure completely, resulting in insufficient interlayer adhesion. These material degradations caused by inaccurate temperature control ultimately directly damage the structural integrity and reliability of the product. Summary of the Invention

[0004] To address the technical problem of temperature control inaccuracy caused by the inability of traditional fixed-parameter PID control to adapt to complex thermal disturbances during the lamination process, the present invention aims to provide an optimized method for the lamination and curing process of multilayer flexible circuit boards. The specific technical solution adopted is as follows:

[0005] One embodiment of the present invention provides an optimization method for the lamination and curing process of multilayer flexible circuit boards, the method comprising:

[0006] The temperature values ​​at different monitoring points on the surface of the multilayer flexible circuit board are obtained at each moment during each lamination cycle; the heat preservation period and the cooling period are determined for each lamination cycle.

[0007] Based on the severity, duration, and frequency of temperature out-of-control conditions at each monitoring point during the insulation period, the temperature stability of each monitoring point during the insulation period is obtained.

[0008] The time period within the heat preservation period is divided into normal temperature time and abnormal temperature time. Based on the uniformity of the spatial distribution of temperature values ​​at all monitoring points during normal temperature time, the changing trend and spatial fluctuation of temperature runaway points during abnormal temperature time, and the temperature stability, the temperature stability uniformity during the heat preservation period is obtained.

[0009] Based on the degree of temperature control abnormality of the circuit board in each pressing cycle, the temperature stability uniformity, and the mass of temperature value decrease at all monitoring points during the cooling period, the pressing effect index of each pressing cycle is obtained.

[0010] Based on the quality of the circuit board after each lamination cycle and the lamination effect index, the lamination process for the next lamination cycle is optimized.

[0011] Furthermore, obtaining the temperature stability of each monitoring point during the heat preservation period includes:

[0012] The moment when the temperature value at each monitoring point exceeds the preset allowable fluctuation range during the insulation period is recorded as the moment when the temperature exceeds the range.

[0013] Calculate the absolute difference between the temperature value at each out-of-range moment for each monitoring point and the two boundary values ​​of the allowable fluctuation range, and select the minimum absolute difference as the temperature out-of-range amplitude; take the maximum value of the temperature out-of-range amplitudes at all out-of-range moments as the target out-of-range amplitude for each monitoring point.

[0014] Obtain all out-of-range moments that occur consecutively in time during the insulation period of each monitoring point to obtain at least one continuous sequence; the number of moments contained in the longest continuous sequence is recorded as the target length for each monitoring point.

[0015] The minimum distance between any two consecutive sequences of each monitoring point is selected as the target interval.

[0016] Based on the target exceedance range, the target length, and the target interval, the temperature stability of each monitoring point during the heat preservation period is obtained.

[0017] Furthermore, the division of time within the heat preservation period into normal temperature periods and abnormal temperature periods includes:

[0018] Select any moment within the heat preservation period as the example moment, and record the monitoring point where the temperature value at the example moment exceeds the preset allowable fluctuation range as the temperature runaway point at the example moment;

[0019] The ratio of the number of temperature out-of-control points to the total number of monitoring points at the example time is used as the anomaly degree. It is determined whether the anomaly degree is greater than or equal to a preset ratio threshold. If it is, the example time is recorded as a temperature abnormal time; otherwise, the example time is recorded as a temperature normal time.

[0020] Furthermore, obtaining the temperature stability and uniformity during the heat preservation period includes:

[0021] The ratio of the number of non-temperature out-of-control points to the total number of monitoring points at each normal temperature moment is taken as the normality; the average of the absolute difference of the temperature values ​​of each pair of monitoring points at each normal temperature moment is used to obtain the overall temperature difference.

[0022] Based on the difference between the normality and the overall temperature, the local temperature uniformity at each normal temperature moment is obtained; the average of the local temperature uniformity at all normal temperature moments during the insulation period is calculated as the normal temperature uniformity during the insulation period.

[0023] A linear fit is performed on the number of temperature runaway points at all temperature anomaly moments, and the slope of the fitted line is taken as the anomaly trend degree; the mean of the anomaly degree at all temperature anomaly moments is calculated and denoted as the anomaly overall degree; the average of the intersection-union ratio of the temperature runaway points at every two adjacent temperature anomaly moments during the heat preservation period is calculated to obtain the type change degree.

[0024] Based on the abnormal trend degree, the abnormal overall degree, and the type change degree, the abnormal temperature uniformity during the heat preservation period is obtained;

[0025] Calculate the arithmetic mean of the normal temperature uniformity and the abnormal temperature uniformity, and multiply the mean of the temperature stability of all monitoring points by the arithmetic mean to obtain the temperature stability uniformity during the heat preservation period.

[0026] Furthermore, obtaining the pressing effect index for each pressing cycle includes:

[0027] The ratio of the absolute difference in temperature values ​​at two boundary moments of the cooling period to the time interval between the two boundary moments at each monitoring point is taken as the actual cooling rate. The absolute difference between the actual cooling rate and the preset ideal cooling rate at each monitoring point is negatively correlated and normalized to obtain the cooling fit degree of each monitoring point.

[0028] Based on the cooling compatibility and temperature stability of the monitoring points, the temperature control anomaly degree is obtained;

[0029] Calculate the average cooling fit of all monitoring points as the overall cooling fit.

[0030] The temperature control anomaly is negatively correlated and normalized. The arithmetic mean of the processing result, the temperature stability uniformity, and the overall cooling fit is used as the pressing effect index for each pressing cycle.

[0031] Furthermore, the acquisition of temperature control anomaly degree includes:

[0032] Select insulation runaway point, cooling runaway point and overall runaway point from all monitoring points; the temperature stability of the insulation runaway point is less than the preset stability threshold and the cooling fit is greater than or equal to the preset fit threshold, the temperature stability of the cooling runaway point is greater than or equal to the preset stability threshold and the cooling fit is less than the preset fit threshold, and the cooling fit of the overall runaway point is less than the preset fit threshold and the temperature stability is less than the preset stability threshold.

[0033] The ratio of the total number of uncontrolled heat preservation points to the total number of uncontrolled cooling points to the total number of monitoring points is taken as the local anomaly ratio; the ratio of the total number of uncontrolled points to the total number of monitoring points is taken as the overall anomaly ratio; the local anomaly ratio and the overall anomaly ratio are weighted and summed to obtain the temperature control anomaly degree.

[0034] Furthermore, the optimization of the pressing process for the next pressing cycle includes:

[0035] Obtain the actual monitoring values ​​of different types of process performance indicators of the circuit board after each lamination cycle, as well as the benchmark reference values ​​of each type of process performance indicator;

[0036] Calculate the difference between the actual monitored value and the benchmark reference value for each type of process performance index, and select the minimum value between the difference and zero as the effective deviation value; obtain the mean of the normalized results of the effective deviation values ​​of all types of process performance indexes, and use it as the process quality index for each pressing cycle;

[0037] The product of the process quality index and the pressing effect index is normalized to obtain the comprehensive effect index for each pressing cycle.

[0038] Obtain the proportional gain coefficient of the PID controller; multiply the difference between constant 2 and the comprehensive effect index and the proportional gain coefficient as the corrected proportional gain coefficient for each pressing cycle;

[0039] Choose any one of the pressing cycles as the example cycle, and obtain the temperature values ​​of each monitoring point at each sampling time during the heat preservation period and cooling period in the next pressing cycle of the example cycle in real time;

[0040] Based on the temperature value of each monitoring point at each sampling moment in the next pressing cycle of the example cycle, the PID controller is updated using the corrected proportional gain coefficient of the example cycle, and the updated PID controller is used to optimize the pressing process at the corresponding moment.

[0041] Furthermore, determining the heat preservation period and cooling period in each pressing cycle includes:

[0042] Determine the target curing temperature of the adhesive used in the lamination cycle of the circuit board;

[0043] Calculate the average temperature value of all monitoring points at each moment in each pressing cycle to obtain the overall temperature value at the corresponding moment.

[0044] The first moment in each pressing cycle is recorded as the initial first analysis moment; it is determined whether the overall temperature value of the first analysis moment and the subsequent N consecutive moments is greater than or equal to the target curing temperature. If not, the adjacent moment of the first analysis moment is taken as the new first analysis moment; if so, the first analysis moment is taken as the dividing moment of heat rise and heat preservation.

[0045] For each time after the heat preservation boundary in each pressing cycle, the difference between the overall temperature value at each time and the next adjacent time is taken as the temperature change value.

[0046] The next time immediately following the heat preservation boundary is recorded as the initial second analysis time. It is determined whether there is a non-negative value among all the temperature change values ​​between the second analysis time and the last second time in each pressing cycle. If so, the next time immediately following the second analysis time is recorded as the new second analysis time. Otherwise, the second analysis time is used as the heat preservation and cooling boundary.

[0047] The time period between the heat preservation boundary moment and the heat preservation and cooling boundary moment within each pressing cycle is recorded as the heat preservation period, and the time period between the heat preservation and cooling boundary moment and the end of its pressing cycle is recorded as the cooling period.

[0048] Furthermore, the degree of abnormality trend and the degree of abnormality overallity are both negatively correlated with the degree of abnormal temperature uniformity, while the degree of type change is positively correlated with the degree of abnormal temperature uniformity.

[0049] Furthermore, N is less than the total number of moments between the heating and heat preservation boundary moment and the end of the pressing cycle at the heating and heat preservation boundary moment.

[0050] The present invention has the following beneficial effects:

[0051] In this embodiment of the invention, temperature stability is quantitatively evaluated by integrating the severity, persistence, and frequency of temperature runaway during the heat preservation period. The static uniformity of temperature distribution in space under normal temperature conditions and the temporal and spatial fluctuations of temperature runaway points under abnormal temperature conditions are considered and coupled with temperature stability to obtain temperature stability uniformity, which characterizes the level of temperature consistency. This enables a comprehensive diagnosis of the thermal state during the heat preservation process. By integrating temperature stability, temperature stability uniformity, and the quality of temperature drop during the cooling period, a pressing effect index is constructed that sensitively and comprehensively reflects the control quality of a single pressing process. Combined with the measured product quality after pressing, the pressing process for the next pressing cycle is dynamically adjusted, forming a closed-loop control loop of process monitoring, effect evaluation, quality verification, and process optimization. This allows the PID controller to transcend the limitations of fixed parameters and adaptively optimize control response characteristics in real time based on actual process performance, significantly improving its adaptability to complex conditions such as nonlinear thermal disturbances and material property fluctuations. This fundamentally ensures the accuracy and stability of pressing temperature control, guaranteeing the consistency and reliability of curing quality and product performance. Attached Figure Description

[0052] To more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0053] Figure 1 A flowchart illustrating the steps of an optimized method for lamination and curing of multilayer flexible circuit boards according to an embodiment of the present invention;

[0054] Figure 2 This is a flowchart illustrating a method for obtaining temperature stability uniformity according to an embodiment of the present invention.

[0055] Figure 3 This is a schematic diagram of a computer device for optimizing the lamination and curing process of multilayer flexible circuit boards, as provided in one embodiment of the present invention. Detailed Implementation

[0056] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a multilayer flexible circuit board lamination and curing process optimization method proposed according to the present invention. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0057] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0058] The following description, in conjunction with the accompanying drawings, details a specific scheme for optimizing the lamination and curing process of a multilayer flexible circuit board provided by the present invention.

[0059] Example 1:

[0060] This invention proposes an optimized method for the lamination and curing process of multilayer flexible circuit boards. Please refer to [link / reference]. Figure 1 The diagram illustrates a flowchart of a method for optimizing the lamination and curing process of a multilayer flexible circuit board according to an embodiment of the present invention. The method includes:

[0061] Step S1: Obtain the temperature values ​​at different monitoring points on the surface of the multilayer flexible circuit board at each moment in each pressing cycle; determine the heat preservation period and cooling period in each pressing cycle.

[0062] Based on the structure and thermal characteristics of the circuit board, key locations on the surface of the multilayer flexible circuit board are selected. These include key points such as the area directly below the hot press plate in the lamination area, areas with dense circuit patterns, the vicinity of the joints between different material layers, and the geometric center and edges of the board surface. This ensures that the temperature at these locations comprehensively and accurately reflects the heating status of the circuit board during the actual lamination cycle. Multiple temperature sensors are installed at key locations on the surface of the multilayer flexible circuit board. Each temperature sensor is installed at a monitoring point, and the temperature value at each monitoring point is collected at each moment during each lamination cycle.

[0063] It is important to note that when selecting temperature sensors such as miniature thin-film thermocouples or flexible thermistors, the selected temperature sensors and their installation methods should meet the requirements of miniaturization, flexibility, and high pressure resistance, so as to ensure that they will not be damaged by physical extrusion during the pressing cycle, nor will they introduce additional stress or affect the uniformity of the pressed layer.

[0064] The lamination cycle typically includes three stages: heating, holding, and cooling, to meet the requirements of adhesive curing and multilayer circuit board bonding. At the start of lamination, the temperature rapidly rises from room temperature to the adhesive's initial curing temperature. Once the temperature reaches the adhesive's optimal curing temperature range, the holding stage begins, maintaining a stable curing temperature to ensure full adhesive curing and thus achieving a strong bond between the circuit board layers. After the holding stage, the temperature is programmed to decrease, allowing the circuit board to cool to room temperature, at which point the lamination cycle is essentially complete.

[0065] Since the goal of the heating stage is to bring the circuit board temperature to the preset curing range, its control logic is relatively clear. However, the temperature stability of the heat preservation stage and the cooling rate of the cooling stage have a more critical impact on the bonding strength, internal stress, and dimensional stability of the final product. Therefore, the focus of this solution is on the process parameters and quality control of the heat preservation and cooling stages, and it is necessary to determine the heat preservation and cooling periods for each pressing cycle.

[0066] In one implementation of this invention, the data acquisition frequency of the temperature sensors at all monitoring points is the same, set to 10 Hz. The implementer can set it according to the specific circumstances.

[0067] Step S2: Based on the severity, duration, and frequency of temperature out of control at each monitoring point during the insulation period, obtain the temperature stability of each monitoring point during the insulation period.

[0068] Temperature stability during the insulation stage is crucial for curing quality. Stable temperatures promote a uniform, high-quality curing state, thus ensuring the physical properties and long-term reliability of the circuit board. Temperature runaway can have irreversible effects on product quality, such as material stress and chemical reaction processes. Monitoring the severity, duration, and frequency of temperature runaway at monitoring points during the insulation period is used to comprehensively evaluate the temperature stability during the insulation stage, obtaining the temperature stability rating.

[0069] Step S3: Divide the time period within the heat preservation period into normal temperature time and abnormal temperature time; based on the uniformity of the spatial distribution of temperature values ​​at all monitoring points during normal temperature time, the changing trend and spatial fluctuation degree of temperature runaway points during abnormal temperature time, and temperature stability, obtain the temperature stability uniformity during the heat preservation period.

[0070] Because the curing reaction of adhesives is highly sensitive to temperature, and its reaction rate and degree of cross-linking directly depend on the heating conditions, the temperature uniformity of multilayer flexible circuit boards during the lamination and insulation stage is crucial. Uneven temperature distribution during curing can directly lead to defects such as circuit board warping, delamination, and internal stress concentration, severely impairing its physical and mechanical properties, dimensional stability, and long-term electrical reliability. Therefore, it is necessary to analyze the temperature uniformity of the circuit board during the insulation stage to improve the overall performance and product yield.

[0071] By dividing the insulation period into two states—normal temperature and abnormal temperature—for differentiated evaluation, this approach considers not only the static uniformity of temperature distribution in space during the normal temperature period (under controlled conditions) but also analyzes the temporal trends and spatial fluctuations of temperature runaway points during the abnormal temperature period (under runaway conditions). This analysis is coupled with an assessment of the temperature stability of the monitoring points during the insulation phase. This method reflects both the steady-state uniformity level and diagnoses the destructive modes and degrees of uniformity caused by abnormal dynamics. Consequently, the temperature stability uniformity accurately reflects the overall performance of temperature stability and uniformity during the insulation process, providing a targeted basis for improving the curing quality and process reliability of circuit boards.

[0072] Step S4: Based on the degree of temperature control abnormality, temperature stability uniformity, and the quality of temperature drop at all monitoring points during the cooling period in each pressing cycle, obtain the pressing effect index for each pressing cycle.

[0073] The lamination quality of a circuit board is a comprehensive result determined by multiple key process steps. The degree of temperature control anomalies during the lamination cycle directly affects the lamination effect. Temperature stability and uniformity affect the lamination effect through the consistency of heat transfer during the insulation phase. Temperature drop quality affects the lamination effect by the controllability of the cooling phase to avoid product defects, thus impacting the lamination effect. A comprehensive evaluation of the lamination effect of the circuit board in each lamination cycle is conducted across three dimensions: insulation uniformity, cooling compliance, and control anomalies, resulting in a lamination effect index. This allows for precise monitoring and optimization of the lamination process.

[0074] Step S5: Optimize the lamination process for the next lamination cycle based on the quality of the circuit board and the lamination effect index after each lamination cycle.

[0075] The lamination effect index originates from real-time analysis of the temperature timing and spatial distribution during the lamination process. It is a process-oriented and predictive indicator, which can sensitively reflect the control quality and consistency risks of process execution, but cannot be equated with the physical quality of the final product. The quality status after the lamination cycle is the result of direct testing of the laminated circuit board, which is a result-oriented and verifiable final quality measure. Combining the two to optimize the lamination process for the next lamination cycle, a closed-loop optimization from process control to product quality assurance is achieved. This effectively avoids problems such as poor adhesive curing caused by temperature fluctuations, allowing the adhesive to cure under optimal temperature conditions, which helps improve the flexibility and interlayer adhesion of the circuit board, thereby improving the overall quality of the circuit board.

[0076] Preferably, in some possible implementations of the embodiments of the present invention, the method for obtaining the heat preservation period and the cooling period includes: determining the target curing temperature of the adhesive used in the lamination cycle of the circuit board; calculating the average temperature value of all monitoring points at each moment in each lamination cycle to obtain the overall temperature value at the corresponding moment; recording the first moment in each lamination cycle as the initial first analysis moment; determining whether the overall temperature value of the first analysis moment and the subsequent N consecutive moments is greater than or equal to the target curing temperature, if not, taking the adjacent moment of the first analysis moment as the new first analysis moment; if so, taking the first analysis moment as the heat preservation boundary moment; for each lamination cycle, the heat preservation period is... After the heat preservation boundary moment, the difference between the overall temperature value of each moment and the next adjacent moment is taken as the temperature change value. The next adjacent moment after the heat preservation boundary moment is recorded as the initial second analysis moment. It is determined whether there is a non-negative value among all the temperature change values ​​between the second analysis moment and the last second moment in each pressing cycle. If so, the next adjacent moment after the second analysis moment is recorded as the new second analysis moment. Otherwise, the second analysis moment is taken as the heat preservation and cooling boundary moment. The time period between the heat preservation boundary moment and the heat preservation and cooling boundary moment in each pressing cycle is recorded as the heat preservation period. The time period between the heat preservation and cooling boundary moment and the end of its pressing cycle is recorded as the cooling period.

[0077] It should be noted that the target curing temperature refers to the minimum temperature threshold required for the adhesive used in the lamination process to complete the curing reaction and form a stable network structure. The overall temperature value reflects the heating state of the entire circuit board; the curing reaction can only proceed effectively when the circuit board temperature reaches the target curing temperature. To avoid misjudgments caused by temperature fluctuations or measurement noise, only when the overall temperature value at the first analysis time and for the subsequent N consecutive analysis times is greater than or equal to the target curing temperature does it indicate that the circuit board has transitioned from the heating state to the temperature maintenance state. At this point, the first analysis time is the boundary between the heating stage and the maintenance stage, denoted as the heating-maintenance boundary time. The direct signal for the end of maintenance is a continuous decrease in temperature. Since the cooling stage in the lamination process usually occurs after the maintenance stage, a second analysis time needs to be set after the heating-maintenance boundary time. When the temperature change value at the second analysis time and for the subsequent time is negative, it indicates that the temperature has entered a monotonically decreasing state, meaning that the lamination process has entered the cooling stage. At this point, the second analysis time is the boundary between the maintenance stage and the cooling stage, denoted as the maintenance-cooling boundary time.

[0078] In one implementation of this invention, N is set to 5, and the implementer can set it according to specific circumstances.

[0079] Preferably, in some possible implementations of the embodiments of the present invention, the method for obtaining temperature stability includes: recording the time when the temperature value of each monitoring point exceeds a preset allowable fluctuation range during the heat preservation period as an out-of-range time; calculating the absolute difference between the temperature value of each out-of-range time corresponding to each monitoring point and the two boundary values ​​of the allowable fluctuation range, and selecting the minimum absolute difference as the temperature out-of-range amplitude; taking the maximum value among all temperature out-of-range amplitudes of out-of-range times as the target out-of-range amplitude for each monitoring point; obtaining all out-of-range times that occur consecutively in time during the heat preservation period of each monitoring point to obtain at least one continuous sequence; recording the number of times contained in the longest continuous sequence as the target length for each monitoring point; selecting the minimum value among the distances between every two adjacent continuous sequences of each monitoring point as the target interval; and obtaining the temperature stability of each monitoring point during the heat preservation period based on the target out-of-range amplitude, the target length, and the target interval.

[0080] It is important to note that during the insulation phase, the temperature must be strictly controlled within the allowable fluctuation range. Any deviation from this range signifies temperature runaway. The magnitude of the temperature deviation quantifies the severity of the runaway, with the target deviation reflecting the most severe runaway scenario, ensuring the worst-case scenario is fully considered. The smaller the target deviation, the closer the most severe temperature deviation is to the ideal range, indicating that the overall temperature during the insulation phase is close to the ideal range, meaning better overall temperature stability during the insulation phase. The length of the continuous sequence measures the persistence of the temperature runaway, with the target length representing the most severe persistent runaway scenario, ensuring the most prolonged runaway problem is considered. The smaller the target length, the shorter the duration of the most prolonged runaway, indicating that the runaway is transient and easier to recover, meaning a stronger ability of the control system to correct temperature deviations and better temperature stability during the insulation phase. The distance between two adjacent continuous sequences reflects the frequency of temperature runaway, with the target interval revealing the most frequent runaway fluctuations. The smaller the target interval, the more frequent the temperature runaway events, indicating more frequent temperature fluctuations, poorer control system regulation capability, and worse temperature stability during the insulation phase. The target exceedance magnitude, target length, and target interval represent the overall performance of the control system under worst-case conditions. Therefore, the target interval is positively correlated with temperature stability, while the target exceedance magnitude and target length are both negatively correlated with temperature stability.

[0081] In this embodiment of the invention, the target exceedance amplitude and target length of each monitoring point are negatively correlated and normalized to obtain standard amplitude and standard length in turn; the target interval of each monitoring point is normalized to obtain standard interval; the arithmetic mean of standard amplitude, standard length and standard interval of each monitoring point is calculated as the temperature stability of each monitoring point during the heat preservation period.

[0082] In this embodiment of the invention, based on the target exceedance amplitude, target length, and target interval corresponding to the heat preservation period in each pressing cycle of all monitoring points of multiple qualified circuit boards of the same type, the Z-score normalization method is used to normalize the target exceedance amplitude, target length, and target interval of the circuit board under analysis in each pressing cycle. The difference between the constant 1 and the normalized result of the target exceedance amplitude and the normalized result of the target length are recorded as the standard amplitude and standard length, respectively. The normalized result of the target interval is used as the standard interval.

[0083] It is important to note that the distance between any two consecutive sequences refers to the time interval between the last moment of the previous sequence and the first moment of the next sequence.

[0084] In one implementation of this invention, the target temperature M during the heat preservation stage of the circuit board lamination process is obtained. This target temperature M refers to the theoretical center temperature value that the process requirements must reach and strive to maintain during the heat preservation stage. Typically, the allowable deviation c is determined by the process engineer based on factors such as product quality standards, equipment capabilities, and safety margins, such as 2 degrees Celsius. Therefore, the preset allowable fluctuation range is... Celsius.

[0085] Preferably, in some possible implementations of the embodiments of the present invention, the method for obtaining abnormal temperature moments and normal temperature moments includes: selecting any moment within the heat preservation period as an example moment; recording the monitoring point where the temperature value at the example moment exceeds a preset allowable fluctuation range as a temperature runaway point at the example moment; taking the ratio of the number of temperature runaway points at the example moment to the total number of monitoring points as the anomaly degree; determining whether the anomaly degree is greater than or equal to a preset ratio threshold; if so, recording the example moment as an abnormal temperature moment; otherwise, recording the example moment as a normal temperature moment.

[0086] It should be noted that the temperature runaway point can pinpoint the specific spatial location of the temperature runaway at each moment. The anomaly quantifies the spatial coverage of the temperature runaway at each moment; the larger this value, the more areas experience temperature runaway, and the worse the overall temperature stability of the circuit board at that moment. In actual processes, there are occasional fluctuations at individual monitoring points. These fluctuations may have a limited impact on the overall quality. A preset proportional threshold is used to distinguish between localized occasional abnormal moments (i.e., normal temperature moments) and large-scale systematic abnormal moments (i.e., abnormal temperature moments). The monitoring points other than the temperature runaway point at each moment are recorded as non-temperature runaway points at that moment, meaning that the temperature value of the non-temperature runaway point at that moment is within the preset allowable fluctuation range.

[0087] In one implementation of this invention, a preset proportional threshold is associated with the target process quality requirements of the circuit board. By learning from historical data, a correlation model is established between the frequency or duration of abnormal temperature moments during the insulation period and the process performance indicators (such as interlayer peel strength and gel content) measured after pressing. The preset proportional threshold is optimized to such that when the abnormal feature quantity identified and statistically analyzed based on the threshold exceeds a certain range, it can reliably predict that the subsequent product quality indicators will exceed the lower limit of acceptance.

[0088] Preferably, in some possible implementations of the embodiments of the present invention, the method for obtaining temperature stability uniformity is described in [reference needed]. Figure 2 The diagram illustrates a flowchart of a method for obtaining temperature stability uniformity according to an embodiment of the present invention, the method comprising:

[0089] Step S310: The ratio of the number of non-temperature out-of-control points to the total number of monitoring points at each normal temperature moment is taken as the normality; the absolute difference between the temperature values ​​of each pair of monitoring points at each normal temperature moment is averaged to obtain the overall temperature difference; based on the normality and the overall temperature difference, the local temperature uniformity at each normal temperature moment is obtained; the mean of the local temperature uniformity at all normal temperature moments during the insulation period is calculated as the normal temperature uniformity during the insulation period.

[0090] It should be noted that the normalization measure is the spatial coverage of areas with normal temperature at each moment. The larger this value, the more areas of the circuit board meet the insulation requirements at the moment of normal temperature, and the better the overall spatial uniformity at that moment. The overall temperature difference reflects the spatial dispersion of the temperature field of the circuit board at the moment of normal temperature. The smaller this value, the closer the temperatures of each monitoring point are, and the better the spatial uniformity. Therefore, the overall temperature difference is negatively correlated with local temperature uniformity, and the normalization measure is positively correlated with local temperature uniformity.

[0091] In this embodiment of the invention, based on the overall temperature difference at all normal temperature moments, the overall temperature difference at each normal temperature moment is normalized using the minimax normalization method. The difference between the constant 1 and the normalized result of the overall temperature difference is taken as the standard overall temperature difference. The product of the normality of each normal temperature moment and the standard overall temperature difference is taken as the local temperature uniformity. The greater the local temperature uniformity, the more uniform the temperature of the circuit board at normal temperature moments. Normal temperature uniformity reflects the uniformity of the spatial temperature distribution of the circuit board during the temperature-controlled period of the insulation stage.

[0092] Step S320: Perform linear fitting on the number of temperature runaway points at all temperature anomaly moments, and use the slope of the fitted line as the anomaly trend degree; calculate the mean of the anomaly degree at all temperature anomaly moments, and record it as the anomaly overall degree; calculate the average of the intersection-union ratio of temperature runaway points at every two adjacent temperature anomaly moments during the insulation period to obtain the type change degree; obtain the anomaly temperature uniformity during the insulation period based on the anomaly trend degree, the anomaly overall degree, and the type change degree.

[0093] In this embodiment of the invention, a two-dimensional space is established with time as the horizontal axis and the number of temperature runaway points at abnormal temperature moments as the vertical axis. The number of temperature runaway points at all abnormal temperature moments is mapped to the two-dimensional space to obtain corresponding scattered points. The least squares method is used to fit the scattered points in the two-dimensional space to obtain a fitted straight line.

[0094] It should be noted that a positive slope on the fitted line indicates that the number of temperature runaway points gradually increases over time. A larger slope indicates a greater likelihood of intensified temperature runaway and more severe damage to the temperature uniformity of the circuit board. A negative slope indicates that temperature runaway has eased and will not damage the temperature uniformity of the circuit board. Therefore, when the slope is negative, the anomaly trend degree is set to zero. The anomaly overall degree measures the overall severity of temperature runaway time during the insulation stage. A larger value indicates a larger range of temperature runaway at the time of the temperature anomaly and more severe damage to the temperature uniformity of the circuit board. If the intersection-union ratio of temperature runaway points at two adjacent temperature anomaly times is smaller, it indicates that the temperature runaway locations at the corresponding two temperature anomaly times are more inconsistent. The temperature anomaly runaway occurs randomly and dispersedly, which means that the temperature field is more non-uniform. The type variation degree reflects the overall spatial fluctuation of temperature runaway points over the anomaly time. Therefore, the anomaly trend degree and the anomaly overall degree are both negatively correlated with the anomaly temperature uniformity, while the type variation degree is positively correlated with the anomaly temperature uniformity. In this embodiment of the invention, the product of the normalized result of the abnormal trend degree and the abnormal overall degree is calculated, and the product of the difference between the constant 1 and the product and the type change degree is used as the abnormal temperature uniformity during the heat preservation period.

[0095] In this embodiment of the invention, based on the abnormal trend degree of qualified circuit boards of the same type during the heat preservation period in each lamination cycle, the abnormal trend degree is normalized using the minimax normalization method. Specifically, the abnormal trend degree of qualified circuit boards of the same type during the heat preservation period is obtained using the same method as described above.

[0096] It is important to note that the analysis set is composed of the temperature runaway points at each temperature anomaly moment. The intersection and union of the analysis sets at each two adjacent temperature anomaly moments are obtained. The ratio of the number of monitoring points in the intersection to the number of monitoring points in the union is used as the intersection-union ratio of the temperature runaway points at the corresponding two temperature anomaly moments.

[0097] Step S330: Calculate the arithmetic mean of normal temperature uniformity and abnormal temperature uniformity, and multiply the mean of temperature stability of all monitoring points by the arithmetic mean to obtain the temperature stability uniformity during the heat preservation period.

[0098] It should be noted that the mean temperature stability reflects the stability level of temperature over time at all monitoring points during the insulation stage. The larger the mean, the better the overall temperature stability of each monitoring point during the insulation stage. Normal temperature uniformity measures the spatial uniformity at normal temperature conditions, while abnormal temperature uniformity measures the impact of abnormal dynamics on uniformity during abnormal temperature conditions. The arithmetic mean of both reflects the spatial uniformity of temperature during the insulation stage. The larger this value, the more uniform the spatial temperature distribution of the circuit board during the insulation stage. A higher temperature stability uniformity indicates a more uniform and stable temperature distribution on the circuit board during the insulation stage, which is more conducive to lamination.

[0099] Preferably, in some possible implementations of the embodiments of the present invention, the method for obtaining the pressing effect index includes: taking the ratio of the absolute difference of the temperature values ​​at two boundary moments of each monitoring point during the cooling period to the time interval between the two boundary moments as the actual cooling rate; performing negative correlation and normalization on the absolute difference between the actual cooling rate and the preset ideal cooling rate of each monitoring point to obtain the cooling fit of each monitoring point; obtaining the temperature control anomaly degree based on the cooling fit and temperature stability of the monitoring points; calculating the mean of the cooling fit of all monitoring points as the overall cooling fit; performing negative correlation and normalization on the temperature control anomaly degree, and taking the arithmetic mean of the processing result, temperature stability uniformity, and overall cooling fit as the pressing effect index.

[0100] It should be noted that deviations from the ideal process design in the actual cooling process at the monitoring point may lead to local microstructural defects or residual stress concentration. The start and end times of the cooling period are the boundary moments, and the actual cooling rate is a physical indicator for evaluating whether the cooling process meets the process requirements. The cooling fit quantifies the degree of matching between the cooling process at the monitoring point and the ideal process; the larger this value, the more the actual cooling process at the monitoring point conforms to the ideal cooling process.

[0101] In this embodiment of the invention, the method for obtaining the temperature control anomaly degree includes: selecting insulation failure points, cooling failure points, and overall failure points from all monitoring points; the temperature stability of the insulation failure point is less than a preset stability threshold and the cooling fit is greater than or equal to a preset fit threshold; the temperature stability of the cooling failure point is greater than or equal to a preset stability threshold and the cooling fit is less than a preset fit threshold; the cooling fit of the overall failure point is less than a preset fit threshold and the temperature stability is less than a preset stability threshold; the ratio of the total number of insulation failure points and cooling failure points to the total number of monitoring points is used as the local anomaly ratio; the ratio of the total number of overall failure points to the total number of monitoring points is used as the overall anomaly ratio; and the local anomaly ratio and the overall anomaly ratio are weighted and summed to obtain the temperature control anomaly degree.

[0102] It should be noted that the heat preservation runaway point refers to the monitoring point where the heat preservation operation was flawed but the cooling operation was successful; the cooling runaway point refers to the monitoring point where the heat preservation operation was successful but the cooling operation was flawed; and the overall runaway point refers to the monitoring point where both the heat preservation and cooling operations were flawed. The local anomaly ratio reflects the proportion of monitoring points with a single-stage runaway, indicating local control defects; the overall anomaly ratio reflects the proportion of monitoring points with a two-stage runaway, indicating the severity of the runaway. Combining the two ratios can comprehensively assess the control anomalies in the pressing process. The greater the temperature control anomaly, the more severe the control anomaly in the pressing process.

[0103] It should be noted that a greater degree of temperature control anomaly indicates more severe control abnormalities during the lamination process, resulting in a greater negative impact on the lamination effect and ultimately a poorer lamination performance. Conversely, a greater degree of temperature stability and uniformity indicates a more uniform and stable temperature distribution during the insulation stage, leading to more consistent heat transfer during lamination, which is beneficial for product quality and results in a better lamination effect. Furthermore, a greater degree of overall cooling fit indicates that the circuit board conforms more closely to the ideal process during the cooling stage, resulting in higher cooling quality, more controllable cooling process, and greater avoidance of product defects caused by improper cooling, thus leading to a better lamination effect. Therefore, a negative correlation exists between temperature control anomaly and the lamination effect index, while both temperature stability and uniformity and overall cooling fit are positively correlated with the lamination effect index.

[0104] Because the risks and hazards of a two-stage uncontrolled process are far greater than those of a single-stage uncontrolled process (cooling or insulation), the weight of the local anomaly ratio should be greater than the weight of the overall anomaly ratio when weighted summing the local anomaly ratio and the overall anomaly ratio. In one implementation of this invention, the weight of the local anomaly ratio is set to 0.3, and the weight of the overall anomaly ratio is set to 0.7. Implementers can set these weights according to specific circumstances.

[0105] In one implementation of this invention, a training sample set is formed by collecting a large amount of historical temperature data and corresponding process performance indicators (such as interlayer peel strength and gel content) generated under a benchmark pressing process that can continuously produce qualified products. The average actual cooling rate during the cooling period in all pressing cycles of all qualified products in the sample set is used as the preset ideal cooling rate. The preset stability threshold and preset fit threshold are set by calculating the average temperature stability and cooling fit of all qualified products in the sample set in each pressing cycle, and combining them with engineering criteria (such as allowable process fluctuation boundaries).

[0106] Preferably, in some possible implementations of the embodiments of the present invention, the method for optimizing the lamination process includes: obtaining the actual monitored values ​​of different types of process performance indicators of the circuit board after each lamination cycle, and the benchmark reference value of each type of process performance indicator; calculating the difference between the actual monitored value and the benchmark reference value of each type of process performance indicator, and selecting the minimum value between the difference and zero as the effective deviation value; obtaining the mean of the normalized results of the effective deviation values ​​of all types of process performance indicators as the process quality index for each lamination cycle; and normalizing the product of the process quality index and the lamination effect index to obtain the result for each lamination cycle. The comprehensive effect index of the period is obtained; the proportional gain coefficient of the PID controller is obtained; the product of the difference between constant 2 and the comprehensive effect index and the proportional gain coefficient is used as the corrected proportional gain coefficient for each pressing cycle; a pressing cycle is randomly selected as the example cycle, and the temperature values ​​of each monitoring point at each sampling time during the heat preservation and cooling periods in the next pressing cycle of the example cycle are obtained in real time; based on the temperature values ​​of each monitoring point at each sampling time in the next pressing cycle of the example cycle, the corrected proportional gain coefficient of the example cycle is used to update the PID controller, and the updated PID controller is used to optimize the pressing process at the corresponding time.

[0107] It should be noted that after each lamination cycle, the stress distribution inside the circuit board is relatively stable, and the adhesion between the layers is fixed. At this point, relevant tests are needed to verify the key quality of the lamination process. In this embodiment of the invention, the process performance indicators include: interlayer peel strength, gel content, and insulation resistance. The actual monitoring values ​​of all types of process performance indicators of the circuit board after each lamination cycle are obtained. The testing methods for these indicators are all well-known technologies and will not be described in detail here. Since flexible circuit boards typically require a peel strength ≥1.5 Newtons per millimeter, the industry default is a gel content ≥90%, and the insulation resistance requirement is ≥1×10¹ when the test voltage is 500 volts DC. 0 For ohms, the reference values ​​for interlayer peel strength, gel content, and insulation resistance are 1.5 N / mm, 90%, and 1 × 10¹, respectively. 0 Ohms, 500 volts DC is required when measuring insulation resistance. Based on the effective deviation values ​​of all types of process performance indicators of multiple qualified circuit boards of the same type after each lamination cycle, the maximum-minimum normalization method is used to normalize the effective deviation values ​​of all types of process performance indicators of the circuit board under analysis after each lamination cycle.

[0108] When the difference between the actual monitored value and the benchmark reference value of the process performance index is positive, it indicates that the lamination effect is better than the standard, and the lamination effect of the circuit board is better; conversely, when the difference is negative, the index fails to meet the standard, and the lamination effect of the circuit board is worse. The process quality index reflects the overall quality level of each lamination cycle; the larger the value, the more reliable the final product quality. The product of the process quality index and the lamination effect index is calculated to achieve mutual verification between process control performance and final product quality, resulting in a comprehensive effect index. If the comprehensive effect index is closer to 1, it indicates that the lamination effect and product quality are better, meaning that the control parameters and production conditions are more matched, and the controller should remain unchanged. If the comprehensive effect index is closer to 0, it indicates that the lamination effect is worse; to improve the sensitivity of the control quantity to deviation and ensure the correction capability, the proportional gain coefficient should be increased, making the correction proportional gain coefficient larger.

[0109] It should be noted that the proportional gain coefficient of the circuit board remains unchanged during the first pressing cycle in the PID control process.

[0110] Starting from the beginning of the heat preservation period in the next pressing cycle of the example cycle, the temperature values ​​of each monitoring point on the circuit board surface are collected in real time at each sampling moment; the time interval between two adjacent sampling moments is 5 seconds, and the method for obtaining the heat preservation and cooling periods is the same for all pressing cycles. Based on the temperature values ​​of each monitoring point at each sampling moment in the next pressing cycle of the example cycle, the PID controller is updated using the corrected proportional gain coefficient of the example cycle to obtain the relevant parameter control quantities for the heat preservation period and cooling time of the next pressing cycle; the control quantities are converted into equipment operations, and the relevant parameters are adjusted so that the temperature at the real-time sampling moment is more in line with normal requirements. For example, during the heat preservation stage, the temperature is controlled by adjusting the power of the heating element to bring it closer to the target temperature, and during the cooling stage, the temperature drop rate is controlled by adjusting the opening of the cooling valve.

[0111] Example 2:

[0112] This invention also presents a schematic diagram of a computer device for optimizing the lamination and curing process of multilayer flexible circuit boards. Please refer to [link / reference]. Figure 3 The computer device includes a memory 601, a processor 602, and a computer program 603 stored in the memory 601 and running on the processor 602. When the processor 602 executes the computer program 603, the computer device can execute any of the aforementioned multilayer flexible circuit board lamination and curing process optimization methods.

[0113] Furthermore, embodiments of this application also protect an apparatus that may include a memory and a processor, wherein the memory stores executable program code, and the processor is used to call and execute the executable program code to execute the multilayer flexible circuit board lamination and curing process optimization method provided in embodiments of this application.

[0114] This embodiment can divide the device into functional modules based on the above method example. For example, each module can correspond to a separate function, or two or more functions can be integrated into one processing module. The integrated module can be implemented in hardware. It should be noted that the module division in this embodiment is illustrative and only represents one logical functional division. In actual implementation, there may be other division methods.

[0115] When each module is divided according to its function, the device may also include a communication module, a signal analysis module, a complexity analysis module, and a positioning module. It should be noted that all relevant content of each step involved in the above method embodiments can be referenced from the functional descriptions of the corresponding functional modules, and will not be repeated here.

[0116] It should be understood that the apparatus provided in this embodiment is used to perform the above-described method for optimizing the lamination and curing process of multilayer flexible circuit boards, and therefore can achieve the same effect as the above-described implementation method.

[0117] When using integrated units, the device may include a processing module and a storage module. When applied to a workpiece, the processing module can be used to control and manage the workpiece's operations. The storage module can be used to support the execution of program code by the workpiece.

[0118] The processing module may be a processor or a controller, which can implement or execute various exemplary logic blocks, modules, and circuits contained in conjunction with the disclosure of this application. The processor may also be a combination of functions that implement computing capabilities, such as a combination of one or more microprocessors, a combination of digital signal processing (DSP) and a microprocessor, etc., and the storage module may be a memory.

[0119] Example 3:

[0120] This embodiment also provides a computer-readable storage medium storing computer program code. When the computer program code is run on a computer, the computer executes the above-described related method steps to implement the multilayer flexible circuit board lamination and curing process optimization method provided in the above embodiment.

[0121] Example 4:

[0122] This embodiment also provides a computer program product. When the computer program product is run on a computer, it causes the computer to perform the above-mentioned related steps to realize the multilayer flexible circuit board lamination and curing process optimization method provided in the above embodiment.

[0123] In this embodiment, the apparatus, computer-readable storage medium, or computer program product are all used to execute the corresponding methods provided above. Therefore, the beneficial effects they can achieve can be referred to the beneficial effects in the corresponding methods provided above, and will not be repeated here.

[0124] In the embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another device, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0125] It should be noted that the order of the above embodiments of the present invention is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. The processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0126] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

Claims

1. An optimized method for the lamination and curing process of multilayer flexible circuit boards, characterized in that, The method includes: The temperature values ​​at different monitoring points on the surface of the multilayer flexible circuit board are obtained at each moment during each lamination cycle; the heat preservation period and the cooling period are determined for each lamination cycle. Based on the severity, duration, and frequency of temperature out-of-control conditions at each monitoring point during the insulation period, the temperature stability of each monitoring point during the insulation period is obtained. The time period within the heat preservation period is divided into normal temperature time and abnormal temperature time. Based on the uniformity of the spatial distribution of temperature values ​​at all monitoring points during normal temperature time, the changing trend and spatial fluctuation of temperature runaway points during abnormal temperature time, and the temperature stability, the temperature stability uniformity during the heat preservation period is obtained. Based on the degree of temperature control abnormality of the circuit board in each pressing cycle, the temperature stability uniformity, and the mass of temperature value decrease at all monitoring points during the cooling period, the pressing effect index of each pressing cycle is obtained. Based on the quality of the circuit board after each lamination cycle and the lamination effect index, the lamination process for the next lamination cycle is optimized. The acquisition of temperature stability at each monitoring point during the insulation period includes: The moment when the temperature value at each monitoring point exceeds the preset allowable fluctuation range during the insulation period is recorded as the moment when the temperature exceeds the range. Calculate the absolute difference between the temperature value at each out-of-range moment for each monitoring point and the two boundary values ​​of the allowable fluctuation range, and select the minimum absolute difference as the temperature out-of-range amplitude; take the maximum value of the temperature out-of-range amplitudes at all out-of-range moments as the target out-of-range amplitude for each monitoring point. Obtain all out-of-range moments that occur consecutively in time during the insulation period of each monitoring point to obtain at least one continuous sequence; the number of moments contained in the longest continuous sequence is recorded as the target length for each monitoring point. The minimum distance between any two consecutive sequences of each monitoring point is selected as the target interval. Based on the target exceedance range, the target length, and the target interval, the temperature stability of each monitoring point during the heat preservation period is obtained; The process of obtaining temperature stability and uniformity during the heat preservation period includes: The ratio of the number of non-temperature out-of-control points to the total number of monitoring points at each normal temperature moment is taken as the normality; the average of the absolute difference of the temperature values ​​of each pair of monitoring points at each normal temperature moment is used to obtain the overall temperature difference. Based on the difference between the normality and the overall temperature, the local temperature uniformity at each normal temperature moment is obtained; the average of the local temperature uniformity at all normal temperature moments during the insulation period is calculated as the normal temperature uniformity during the insulation period. A linear fit is performed on the number of temperature runaway points at all temperature anomaly moments, and the slope of the fitted line is taken as the anomaly trend degree; the mean of the anomaly degree at all temperature anomaly moments is calculated and denoted as the anomaly overall degree; the intersection-union ratio of the temperature runaway points at each of the two adjacent temperature anomaly moments during the heat preservation period is averaged to obtain the type change degree. Based on the abnormal trend degree, the abnormal overall degree, and the type change degree, the abnormal temperature uniformity during the heat preservation period is obtained; Calculate the arithmetic mean of the normal temperature uniformity and the abnormal temperature uniformity, and multiply the mean of the temperature stability of all monitoring points by the arithmetic mean to obtain the temperature stability uniformity during the heat preservation period. The process of obtaining the pressing effect index for each pressing cycle includes: The ratio of the absolute difference in temperature values ​​at two boundary moments of the cooling period to the time interval between the two boundary moments at each monitoring point is taken as the actual cooling rate. The absolute difference between the actual cooling rate and the preset ideal cooling rate at each monitoring point is negatively correlated and normalized to obtain the cooling fit degree of each monitoring point. Based on the cooling compatibility and temperature stability of the monitoring points, the temperature control anomaly degree is obtained; Calculate the average cooling fit of all monitoring points as the overall cooling fit. The temperature control anomaly is negatively correlated and normalized, and the arithmetic mean of the processing result, the temperature stability uniformity, and the overall cooling fit is used as the pressing effect index for each pressing cycle. The optimization of the pressing process for the next pressing cycle includes: Obtain the actual monitoring values ​​of different types of process performance indicators of the circuit board after each lamination cycle, as well as the benchmark reference values ​​of each type of process performance indicator; Calculate the difference between the actual monitored value and the benchmark reference value for each type of process performance index, and select the minimum value between the difference and zero as the effective deviation value; obtain the mean of the normalized results of the effective deviation values ​​of all types of process performance indexes, and use it as the process quality index for each pressing cycle; The product of the process quality index and the pressing effect index is normalized to obtain the comprehensive effect index for each pressing cycle. Obtain the proportional gain coefficient of the PID controller; multiply the difference between constant 2 and the comprehensive effect index and the proportional gain coefficient as the corrected proportional gain coefficient for each pressing cycle; Choose any one of the pressing cycles as the example cycle, and obtain the temperature values ​​of each monitoring point at each sampling time during the heat preservation period and cooling period in the next pressing cycle of the example cycle in real time; Based on the temperature value of each monitoring point at each sampling moment in the next pressing cycle of the example cycle, the PID controller is updated using the corrected proportional gain coefficient of the example cycle, and the updated PID controller is used to optimize the pressing process at the corresponding moment.

2. The method for optimizing the lamination and curing process of multilayer flexible circuit boards according to claim 1, characterized in that, The division of time within the heat preservation period into normal temperature periods and abnormal temperature periods includes: Select any moment within the heat preservation period as the example moment, and record the monitoring point where the temperature value at the example moment exceeds the preset allowable fluctuation range as the temperature runaway point at the example moment; The ratio of the number of temperature out-of-control points to the total number of monitoring points at the example time is used as the anomaly degree. It is determined whether the anomaly degree is greater than or equal to a preset ratio threshold. If it is, the example time is recorded as a temperature abnormal time; otherwise, the example time is recorded as a temperature normal time.

3. The method for optimizing the lamination and curing process of multilayer flexible circuit boards according to claim 1, characterized in that, The acquisition of temperature control anomaly degree includes: From all monitoring points, select the insulation runaway point, the cooling runaway point, and the overall runaway point; the temperature stability of the insulation runaway point is less than the preset stability threshold and the cooling fit is greater than or equal to the preset fit threshold; the temperature stability of the cooling runaway point is greater than or equal to the preset stability threshold and the cooling fit is less than the preset fit threshold; the cooling fit of the overall runaway point is less than the preset fit threshold and the temperature stability is less than the preset stability threshold. The ratio of the total number of uncontrolled heat preservation points to the total number of uncontrolled cooling points to the total number of monitoring points is taken as the local anomaly ratio; the ratio of the total number of uncontrolled points to the total number of monitoring points is taken as the overall anomaly ratio; the local anomaly ratio and the overall anomaly ratio are weighted and summed to obtain the temperature control anomaly degree.

4. The method for optimizing the lamination and curing process of multilayer flexible circuit boards according to claim 1, characterized in that, Determining the heat preservation period and cooling period in each pressing cycle includes: Determine the target curing temperature of the adhesive used in the lamination cycle of the circuit board; Calculate the average temperature value of all monitoring points at each moment in each pressing cycle to obtain the overall temperature value at the corresponding moment. The first moment in each pressing cycle is recorded as the initial first analysis moment; it is determined whether the overall temperature value of the first analysis moment and the subsequent N consecutive moments is greater than or equal to the target curing temperature. If not, the adjacent moment of the first analysis moment is taken as the new first analysis moment; if so, the first analysis moment is taken as the dividing moment of heat rise and heat preservation. For each time after the heat preservation boundary in each pressing cycle, the difference between the overall temperature value at each time and the next adjacent time is taken as the temperature change value. The next time immediately following the heat preservation boundary is recorded as the initial second analysis time. It is determined whether there is a non-negative value among all the temperature change values ​​between the second analysis time and the last second time in each pressing cycle. If so, the next time immediately following the second analysis time is recorded as the new second analysis time. Otherwise, the second analysis time is used as the heat preservation and cooling boundary. The time period between the heat preservation boundary moment and the heat preservation and cooling boundary moment within each pressing cycle is recorded as the heat preservation period, and the time period between the heat preservation and cooling boundary moment and the end of its pressing cycle is recorded as the cooling period.

5. The method for optimizing the lamination and curing process of multilayer flexible circuit boards according to claim 1, characterized in that, The degree of abnormality trend and the degree of abnormality are both negatively correlated with the degree of abnormal temperature uniformity, while the degree of type change is positively correlated with the degree of abnormal temperature uniformity.

6. The method for optimizing the lamination and curing process of a multilayer flexible circuit board according to claim 4, characterized in that, N is less than the total number of moments between the heating and insulation boundary moment and the end of the pressing cycle at the heating and insulation boundary moment.

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