Flexible circuit board electrical performance testing method and system

Abstract

The application relates to the technical field of circuit board performance testing, in particular to a flexible circuit board electrical performance testing method and system, which comprises the following steps: obtaining the resistance values of a flexible circuit board before and after bending test, which are measured at different temperatures for multiple times; analyzing the change of the resistance values of the flexible circuit board at different temperatures and the fluctuation degree of the resistance values measured at each temperature, so as to obtain the resistance instability degree of the flexible circuit board at each temperature; calculating the resistance instability trend degree of the flexible circuit board through the change trend of the resistance instability degree of the flexible circuit board, and then obtaining a resistance correction coefficient; calculating the resistance change rate of the flexible circuit board, correcting the resistance change rate of the flexible circuit board through the basic deviation rate and the resistance correction coefficient, so as to test the electrical performance of the flexible circuit board. The application can improve the performance testing precision of the circuit board.

Description

Technical Field

[0001] This application relates to the field of circuit board performance testing technology, specifically to a method and system for testing the electrical performance of flexible circuit boards. Background Technology

[0002] Flexible circuit boards (PCBs) are bendable circuit boards made with polyimide or polyester film as the substrate. Their key electrical performance parameters include impedance control of conductive lines, signal integrity, insulation resistance, withstand voltage, and high-frequency transmission characteristics. Improper impedance matching or excessive signal attenuation can lead to data transmission errors and communication interruptions. Especially in 5G communication, high-precision medical instruments, and high-speed computing scenarios, electrical performance defects in flexible circuit boards can cause system timing disorders, increased bit error rates, and even system malfunctions. Therefore, it is necessary to measure the electrical performance of flexible circuit boards to ensure a high pass rate for products leaving the factory.

[0003] The electrical performance testing of flexible circuit boards is judged by whether the rate of change of resistance after bending is less than a predetermined value. However, bending may cause cracks in the flexible circuit board, and temperature can cause drastic fluctuations in the resistance value. The traditional method of obtaining the rate of change of resistance of flexible circuit boards through curve fitting is prone to low fitting accuracy in local areas, resulting in a decrease in the accuracy of electrical performance testing of flexible circuit boards. Summary of the Invention

[0004] To address the aforementioned technical problems, the purpose of this application is to provide a method and system for testing the electrical performance of flexible circuit boards. The specific technical solution adopted is as follows: This application provides a method for testing the electrical performance of a flexible circuit board, including the following steps: Obtain the resistance values ​​of the flexible circuit board before and after bending at different temperatures, and obtain the resistance sequence before bending and the measured resistance sequence, respectively. For flexible circuit boards before and after bending, the changes in resistance values ​​of the flexible circuit boards under different temperatures and the degree of fluctuation of resistance values ​​measured multiple times at each temperature are analyzed, so as to obtain the resistance instability of the flexible circuit boards before and after bending at each temperature. For the flexible circuit board before and after bending, the resistance instability trend of the flexible circuit board before and after bending is obtained by the change trend of the resistance instability of the flexible circuit board, and the resistance correction coefficient is obtained by the ratio between the resistance instability trend of the flexible circuit board before and after bending. The resistance change rate of the flexible circuit board is calculated by analyzing the degree of change in the resistance value after bending. The basic deviation rate is obtained by the ratio of the difference between the resistance value of the flexible circuit board after bending and the fitted value. The resistance change rate of the flexible circuit board is corrected by combining the resistance correction coefficient. The electrical properties of the flexible circuit board after bending were tested using the corrected rate of change of resistance. The formula for obtaining the resistance instability is: In the formula, This represents the resistive instability of the flexible circuit board at the i-th temperature after bending. This represents the intensity of the resistance change of the flexible circuit board at the i-th temperature; This represents the minimum value of the change in resistance at all temperatures; This represents the resistance fluctuation of the flexible circuit board at the i-th temperature after bending. This represents the first preset constant; This represents the function that takes the absolute value. The resistive instability of the flexible circuit board under all temperatures after bending is arranged in ascending order of temperature to form a resistive instability sequence. After fitting, the slope of the straight line is calculated as the instability change rate. The ratio of the maximum to the minimum absolute value of all first-order difference values ​​in the resistive instability sequence is calculated. The product of this ratio and the instability change rate is taken as the resistive instability trend. Calculate the product of the basic deviation rate and the resistance correction coefficient, and sum the product with the resistance change rate of the flexible circuit board. Use this sum as the correction resistance change rate of the flexible circuit board.

[0005] Preferably, the resistance values ​​of the flexible circuit board before and after bending at all temperatures are arranged in ascending order of temperature to form a resistance sequence before bending and a measured resistance sequence. The difference value of each resistance value in the measured resistance sequence is obtained using a first-order difference algorithm and recorded as the resistance change intensity at each temperature. The standard deviation of the resistance values ​​of the flexible circuit board after bending at each temperature is used as the resistance fluctuation of the flexible circuit board after bending at each temperature.

[0006] Preferably, a fitted straight line is obtained by fitting the resistive instability sequence. When the slope of the fitted straight line is greater than or equal to 0, the rate of change of instability is equal to the slope of the fitted straight line; otherwise, the rate of change of instability is 0.

[0007] Preferably, when the ratio between the resistance instability tendency of the flexible circuit board after bending and before bending is less than 1, the resistance correction coefficient is set to zero; when the ratio between the resistance instability tendency of the flexible circuit board after bending and before bending is greater than or equal to 1, the resistance correction coefficient is the difference between the ratio and 1.

[0008] Preferably, the measurement fitting curve corresponding to the measured resistance sequence is obtained by fitting the curve, and the ratio of the range of the measurement fitting curve to the mean of all resistance values ​​in the measured resistance sequence is obtained. The preset ideal resistance change rate is subtracted from the ratio to obtain the resistance change rate of the flexible circuit board. The average value of the absolute value of the difference between each resistance value in the measured resistance sequence and the corresponding fitted value is obtained, and then divided by the mean of all resistance values. The result of the division is used as the basic deviation rate.

[0009] Preferably, the electrical performance of the flexible circuit board is normal when the rate of change of the correction resistor is less than or equal to a preset threshold; otherwise, the electrical performance of the flexible circuit board is problematic.

[0010] This application also provides a flexible circuit board electrical performance testing system, including a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, it implements the steps of any of the above-described flexible circuit board electrical performance testing methods.

[0011] As can be seen from the above, the flexible circuit board electrical performance testing method and system provided in this application have at least the following beneficial effects: This application calculates the resistance instability by analyzing the difference between the resistance fluctuation after bending and the resistance change before bending, thereby reducing test interference caused by nonlinear material fluctuations, eliminating temperature drift disturbances, and improving the accuracy and efficiency of crack identification. Furthermore, this application assesses the cumulative state of resistance fluctuations during temperature rise by evaluating the resistance instability trend, correcting the bias caused by insufficient accuracy of traditional fitting in local areas, reducing the possibility of normal material fluctuations being misjudged as crack damage, and improving the reliability of electrical performance assessment. This application combines the resistance instability trend with the basic deviation rate, prioritizing correction and compensation for high-instability, high-deviation samples, and retaining the original change rate for low-instability samples, adapting to the differences in material composition between different batches, and improving the accuracy of electrical performance testing of flexible circuit boards. Attached Figure Description

[0012] Figure 1 A flowchart illustrating the steps of a method for testing the electrical performance of a flexible circuit board provided in this application. Detailed Implementation

[0013] The following description, in conjunction with the accompanying drawings, details the specific scheme of the flexible circuit board electrical performance testing method and system provided in this application.

[0014] Please see Figure 1 The diagram illustrates a flowchart of a method for testing the electrical performance of a flexible circuit board according to an embodiment of this application, including the following steps: Step 1: Obtain the resistance values ​​of the flexible circuit board before and after bending at different temperatures, and obtain the resistance sequence before bending and the measured resistance sequence.

[0015] In this embodiment, the first flexible circuit board in each batch is tested for non-destructive testing. When the flexible circuit board is deemed non-destructive, its resistance is measured using a DCV test before performing a bending test. The test temperature is -40°C. By 85 From -40 Start by increasing by 1 each time. In this embodiment, the resistance value of the flexible circuit board is tested 10 times each time the temperature increases, and the average resistance value is calculated to eliminate the influence of extreme values. This average value is recorded as the resistance value of the flexible circuit board before bending after each temperature increase. The resistance values ​​before bending at all temperatures are arranged in ascending order of measurement temperature to obtain the resistance sequence of the flexible circuit board before bending. The non-destructive testing techniques include image detection, X-ray imaging, and ultrasonic scanning. In this embodiment, image detection is used. Its calculation is a well-known technique, and the specific calculation steps will not be described here. The above 10 consecutive tests are conducted during the thermal stress release stage after the thermal cycling test chamber has just reached the target temperature. This is used to capture the transient resistance fluctuations caused by thermal creep of microcracks at that temperature.

[0016] Furthermore, in this embodiment, the flexible circuit board that has passed the non-destructive testing method is subjected to a bending test using a bending resistance testing machine. The number of bends in this embodiment is 100,000. It should be noted that after the bending test, the operator needs to determine if there is any external damage to the flexible circuit board. If external damage exists, the flexible circuit board fails the bending test and its electrical performance is not tested. Only flexible circuit boards without external damage are subjected to subsequent electrical performance testing. During the test, the temperature in the environment of the flexible circuit board is adjusted using a thermal cycling test chamber, and the resistance in the flexible circuit board is obtained using DCV testing. The test temperature is -40°C. By 85 From -40 Start by increasing by 1 each time. Preferably, in this embodiment, the resistance value of the flexible circuit board is tested 10 times each time the temperature increases, and the average resistance value is calculated as the resistance value of the flexible circuit board after bending after each temperature increase, and recorded as the measured resistance value. In this embodiment, the influence of extreme values ​​is eliminated by averaging the resistance values ​​of multiple measurements. The measured resistance values ​​of the flexible circuit board at all temperatures after bending are arranged in ascending order of measurement temperature to obtain the measured resistance sequence of the flexible circuit board.

[0017] Step 2: For the flexible circuit board before and after bending, analyze the change in resistance value of the flexible circuit board at different temperatures and the degree of fluctuation of the resistance value measured multiple times at each temperature, so as to obtain the resistance instability of the flexible circuit board before and after bending at each temperature.

[0018] For a flexible circuit board that has not been bent, its resistance and temperature will show an approximately linear relationship. The higher the temperature of the flexible circuit board, the higher its resistance value, showing a strong linear relationship. Therefore, the state of the flexible circuit board can be identified by the relationship between temperature and resistance.

[0019] After a flexible circuit board is bent, the copper foil may develop cracks invisible to the naked eye. As the ambient temperature of the flexible circuit board rises, these cracks expand, compressing the effective conductive paths and causing a sharp increase in the resistance of the flexible circuit board. This results in significant fluctuations and a decline in the electrical performance of the flexible circuit board. The stronger the rate of increase in resistance with rising temperature, the more severe the crack propagation, the more the conductive path of the flexible circuit board is obstructed, the lower the circuit reliability, and the lower the electrical performance of the flexible circuit board. This can seriously affect the lifespan and stability of subsequent electronic products.

[0020] Therefore, the stronger the rate of resistance change and the stronger the local fluctuations in the flexible circuit board, the more likely the flexible circuit board is to crack, affecting its electrical performance. The measured resistance sequence is used as input to a first-order differential algorithm. The algorithm outputs the difference between the resistance values ​​in the measured resistance sequence, denoted as the resistance change intensity. Note: For the difference value of the last element in the measured resistance sequence, linear interpolation is used for completion. Ideally, the resistance change intensity at each temperature should be the same or similar. After cracking, the resistance change intensity at each temperature shows a large deviation. Therefore, the resistance instability of the flexible circuit board at each temperature is calculated to characterize the instability state of resistance as it changes with temperature. In this embodiment, the formula for calculating the resistance instability of the flexible circuit board at each temperature after bending is: In the formula, This represents the resistive instability of the flexible circuit board at the i-th temperature after bending. This represents the intensity of the resistance change of the flexible circuit board at the i-th temperature; This represents the minimum value of the resistance change intensity across all temperature ranges. The resistance fluctuation of the flexible circuit board at the i-th temperature is represented by the standard deviation of all resistance values ​​of the flexible circuit board after bending at the i-th temperature. This represents the function that takes the absolute value. This represents the first preset constant to prevent the denominator from being 0. In this embodiment, the value is taken as the average value of the intensity of all temperature resistance changes.

[0021] On the right side of the equation above, the numerator and denominator of the first product factor are parameters with the same dimensions, so the ratio of the numerator to the denominator is a dimensionless parameter; the second product factor is a dimensional parameter. There is no dimensional conflict between multiplying a dimensionless parameter and a dimensional parameter.

[0022] The variation in resistance at different temperatures reflects the change in resistance of the flexible circuit board as temperature changes. In this embodiment, considering that the flexible circuit board may be bent during use, bending may cause cracks in the copper foil within the flexible circuit board. These cracks lead to instability in the measured resistance, causing fluctuations in the resistance measured at the same temperature. Therefore, the difference between the intensity of the resistance change at this temperature and its minimum value can characterize the degree of deviation of the resistance from the overall change; simultaneously, the standard deviation of the measured resistance values ​​characterizes the resistance change of the flexible circuit board. Thus, the product of these two indicators yields the resistance instability of the flexible circuit board at this temperature, characterizing the resistance instability state of the flexible circuit board.

[0023] Accordingly, for the resistance sequence of the flexible circuit board before bending, the resistance instability of the flexible circuit board at each temperature after bending is calculated according to the method described in this embodiment.

[0024] Step 3: For the flexible circuit board before and after bending, obtain the resistance instability trend of the flexible circuit board before and after bending by observing the change trend of the resistance instability of the flexible circuit board. Then, obtain the resistance correction coefficient by using the deviation between the resistance instability trend of the flexible circuit board before and after bending.

[0025] When cracks appear in a flexible circuit board, the contact state of the copper foil becomes unstable, causing fluctuations in the resistance of the flexible circuit board at different times under the same temperature. As the temperature rises, the copper foil expands, accelerating the deformation between the cracks and further reducing the stability of the resistance. Therefore, the intensity of the resistance fluctuation increases with the temperature of the flexible circuit board. The greater the increase in intensity, the longer and more numerous the cracks in the flexible circuit board, and the more it affects the electrical performance of the flexible circuit board.

[0026] For undamaged flexible circuit boards, the resistance is relatively stable, remaining essentially unchanged at the same temperature, but increasing with rising temperature. The resistance instability at the temperature described above is calculated using the intensity of the resistance change, ensuring that the resistance instability values ​​at different temperatures are similar and relatively small. Compared to the occurrence of cracks, there is no strong upward trend.

[0027] Therefore, the resistive instability of the flexible circuit board under all the aforementioned temperatures after bending is arranged in ascending order of the corresponding temperature to obtain the resistive instability sequence of the flexible circuit board. The stronger the increasing trend of the resistive instability sequence, the higher the probability of cracking in the flexible circuit board. Therefore, firstly, the resistive instability sequence is used as the input of the linear least squares method, where the elements in the resistive instability sequence are the dependent variables, and the corresponding temperature values ​​are the independent variables. The algorithm outputs a fitted straight line of the resistive instability sequence, and the slope of the fitted line is obtained to characterize the trend strength of the resistive instability sequence, i.e., the increase in instability strength per degree Celsius increase in temperature. Further, the rate of change of instability of the resistive instability sequence is obtained using the slope of the fitted line. When the slope of the fitted line is greater than or equal to 0, the rate of change of instability is equal to the slope of the fitted line; otherwise, the rate of change of instability is 0.

[0028] Furthermore, the resistance instability sequence is used as input to the first-order difference algorithm. The absolute value of the first-order difference output is taken to characterize the intensity of instability change with each degree Celsius increase in temperature. All first-order difference values ​​are then normalized to their maximum and minimum values ​​to prevent errors caused by inconsistencies in dimensions during subsequent ratio calculations. The linear least squares method and the first-order difference algorithm are well-known techniques, and their specific calculation steps will not be elaborated here.

[0029] Therefore, the resistance instability trend degree of the flexible circuit board after bending is calculated to characterize the change in resistance instability trend of the flexible circuit board. In this embodiment, the ratio of the maximum to the minimum absolute value of all first-order difference values ​​in the resistance instability sequence is calculated, and the product of this ratio and the instability change rate is taken as the resistance instability trend degree. In the process of ratio calculation, in order to avoid the denominator being zero, a second preset constant is added to the denominator to prevent the denominator from being 0. The value range is [0.1, 1], and in this embodiment, the value is 0.1.

[0030] The slope of the data fitting can characterize the intensity of the data change trend. In this embodiment, considering that the resistance instability of the flexible circuit board with cracks will increase with the rise in temperature, and the amount of increase is not a fixed value, the maximum and minimum values ​​of all first-order difference values ​​in the resistance instability sequence will have a large difference. At the same time, the slope of the fitting line of the resistance instability sequence will increase. Therefore, the greater the resistance instability trend of the flexible circuit board, the more the electrical performance of the flexible circuit board will decline.

[0031] Furthermore, in order to obtain an accurate comparison benchmark, the resistance instability tendency of the flexible circuit board before bending is calculated according to the same calculation process as that used for measuring the resistance sequence, based on the resistance sequence before bending. This indicates the degree of resistance instability of the flexible circuit board before bending.

[0032] Therefore, in this embodiment, the resistance correction coefficient of the flexible circuit board is calculated based on the deviation between the resistance instability tendency of the flexible circuit board before and after bending. In this embodiment, when the ratio between the resistance instability tendency of the flexible circuit board after bending and before bending is less than 1, the resistance correction coefficient is set to zero; when the ratio is greater than or equal to 1, the resistance correction coefficient is the difference between the ratio and 1. It should be noted that all parameters in this process are dimensionless; therefore, there is no problem of calculation error caused by inconsistent dimensions.

[0033] Thus, according to the above process in this embodiment, the resistance correction coefficient of the flexible circuit board can be obtained, which is used to correct the resistance change of the flexible circuit board after bending.

[0034] Step 4: Analyze the degree of change in the resistance value of the flexible circuit board after bending and calculate the resistance change rate of the flexible circuit board. Obtain the basic deviation rate by the difference between the resistance value of the flexible circuit board after bending and the fitted value. Combine the resistance correction coefficient to correct the resistance change rate of the flexible circuit board.

[0035] When analyzing the resistance of a flexible circuit board, it is necessary to maintain the resistance within a reasonable range. However, since the material composition is not necessarily completely uniform, the resistance change of the flexible circuit board is not linear, resulting in nonlinear fluctuations. Therefore, the measured resistance sequence is used as input to a nonlinear least squares method to obtain the corresponding measurement fitting curve. It should be noted that this embodiment uses a polynomial fitting function to fit the measured resistance sequence; the specific fitting process is existing technology and will not be elaborated in this embodiment.

[0036] Furthermore, the ratio of the range of the measured fitted curve to the mean of all resistance values ​​in the measured resistance sequence is obtained. This ratio is then subtracted from the preset ideal resistance change rate to obtain the resistance change rate of the flexible circuit board. Simultaneously, the average of the absolute values ​​of the differences between each resistance value and its corresponding fitted value in the measured resistance sequence is obtained, and then divided by the mean of all resistance values. The result of this division is used as the basic deviation rate. In this embodiment, the ideal resistance change rate is calculated as follows: the temperature of the flexible circuit board in this embodiment is -40°C. By 85 Its maximum temperature difference is 125. The ideal resistance change rate is obtained by multiplying the maximum temperature difference by the temperature coefficient of resistance of the circuit material. In this embodiment, pure copper is used as an example, and its temperature coefficient of resistance is 0.00393 / ℃. Therefore, the ideal resistance change rate is 49.12%.

[0037] Furthermore, based on the resistance correction coefficient and the basic deviation rate of the flexible circuit board, the resistance change rate of the flexible circuit board is corrected. In this embodiment, the product of the basic deviation rate and the resistance correction coefficient is calculated, and the sum of this product and the resistance change rate of the flexible circuit board is taken as the corrected resistance change rate of the flexible circuit board. All parameters are dimensionless.

[0038] In existing technologies, data can be corrected by analyzing the deviation between the data and the ideal data. In this embodiment, considering that bending may cause cracks in the flexible circuit board, leading to fluctuations in its resistance, a resistance correction coefficient for the flexible circuit board is obtained by comparing its undamaged state with its bent state. This coefficient is then used to correct the rate of resistance change of the flexible circuit board after bending, making the corrected rate of resistance change more accurately reflect the degree of bending damage, thereby improving the accuracy of electrical performance testing.

[0039] Step 5: Use the corrected resistance change rate to test the electrical performance of the flexible circuit board.

[0040] Furthermore, based on the calculated change rate of the correction resistance of the flexible circuit board, the electrical performance of the flexible circuit board after bending is tested. Specifically, when the change rate of the correction resistance is less than or equal to a preset threshold, it indicates that the electrical performance of the flexible circuit board is good and normal; when the change rate of the correction resistance is greater than the preset threshold, it indicates that there is a problem with the electrical performance of the flexible circuit board. In this embodiment, the preset threshold is set to 10%.

[0041] Based on the same inventive concept as the above method, this application also provides a flexible circuit board electrical performance testing system, including a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, it implements the steps of any of the above-described flexible circuit board electrical performance testing methods.

[0042] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Any equivalent structural or procedural transformations made based on the description and drawings of this application, or direct or indirect applications in other related technical fields, are similarly included within the protection scope of this application.

Claims

1. A method for testing the electrical performance of a flexible circuit board, characterized in that, Includes the following steps: Obtain the resistance values ​​of the flexible circuit board before and after bending at different temperatures, and obtain the resistance sequence before bending and the measured resistance sequence, respectively. For flexible circuit boards before and after bending, the changes in resistance values ​​of the flexible circuit boards under different temperatures and the degree of fluctuation of resistance values ​​measured multiple times at each temperature are analyzed, so as to obtain the resistance instability of the flexible circuit boards before and after bending at each temperature. For the flexible circuit board before and after bending, the resistance instability trend of the flexible circuit board before and after bending is obtained by the change trend of the resistance instability of the flexible circuit board, and the resistance correction coefficient is obtained by the ratio between the resistance instability trend of the flexible circuit board before and after bending. The resistance change rate of the flexible circuit board is calculated by analyzing the degree of change in the resistance value after bending. The basic deviation rate is obtained by the ratio of the difference between the resistance value of the flexible circuit board after bending and the fitted value. The resistance change rate of the flexible circuit board is corrected by combining the resistance correction coefficient. The electrical properties of the flexible circuit board after bending were tested using the corrected rate of change of resistance. The formula for obtaining the resistance instability is: In the formula, This represents the resistive instability of the flexible circuit board at the i-th temperature after bending. This represents the intensity of the resistance change of the flexible circuit board at the i-th temperature; This represents the minimum magnitude of the change in resistance at all temperatures; This represents the resistance fluctuation of the flexible circuit board at the i-th temperature after bending. This represents the first preset constant; This represents the function that takes the absolute value. The resistive instability of the flexible circuit board under all temperatures after bending is arranged in ascending order of temperature to form a resistive instability sequence. After fitting, the slope of the straight line is calculated as the instability change rate. The ratio of the maximum to the minimum absolute value of all first-order difference values ​​in the resistive instability sequence is calculated. The product of this ratio and the instability change rate is taken as the resistive instability trend. Calculate the product of the basic deviation rate and the resistance correction coefficient, and sum the product with the resistance change rate of the flexible circuit board. This sum is taken as the correction resistance change rate of the flexible circuit board.

2. The method for testing the electrical performance of a flexible circuit board as described in claim 1, characterized in that, The resistance values ​​of the flexible circuit board before and after bending at all temperatures are arranged in ascending order of temperature to form the resistance sequence before bending and the measured resistance sequence. The difference value of each resistance value in the measured resistance sequence is obtained by using the first-order difference algorithm and recorded as the resistance change intensity at each temperature. The standard deviation of the resistance values ​​of the flexible circuit board after bending at each temperature is taken as the resistance fluctuation of the flexible circuit board after bending at each temperature.

3. The method for testing the electrical performance of a flexible circuit board as described in claim 1, characterized in that, A fitted straight line is obtained by fitting the resistive instability sequence. When the slope of the fitted straight line is greater than or equal to 0, the rate of change of instability is equal to the slope of the fitted straight line; otherwise, the rate of change of instability is 0.

4. The method for testing the electrical performance of a flexible circuit board as described in claim 1, characterized in that, When the ratio between the resistance instability tendency of the flexible circuit board after bending and before bending is less than 1, the resistance correction coefficient is set to zero; when the ratio between the resistance instability tendency of the flexible circuit board after bending and before bending is greater than or equal to 1, the resistance correction coefficient is the difference between the ratio and 1.

5. The method for testing the electrical performance of a flexible circuit board as described in claim 1, characterized in that, The measurement fitting curve corresponding to the measured resistance sequence is obtained by fitting the curve. The ratio of the range of the measurement fitting curve to the mean of all resistance values ​​in the measured resistance sequence is obtained. The ratio is then subtracted from the preset ideal resistance change rate to obtain the resistance change rate of the flexible circuit board. The preset ideal resistance change rate is the maximum temperature difference within the test temperature range of the flexible circuit board multiplied by the temperature coefficient of resistance of the circuit material. The average value of the absolute difference between each resistance value and its corresponding fitted value in the measured resistance sequence is obtained, and then divided by the average value of all resistance values. The result of this division is used as the basic deviation rate.

6. The method for testing the electrical performance of a flexible circuit board as described in claim 1, characterized in that, When the rate of change of the correction resistor is less than or equal to the preset threshold, the electrical performance of the flexible circuit board is normal; otherwise, the electrical performance of the flexible circuit board is problematic.

7. A flexible circuit board electrical performance testing system, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the flexible circuit board electrical performance testing method as described in any one of claims 1-6.

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