Method for determining warpage of circuit board and electronic device

Abstract

This application discloses a method for determining the warpage of a circuit board and an electronic device, relating to the field of circuit board manufacturing quality inspection technology. It addresses the relationship between the change in conductor length and the warpage height. A second functional relationship is determined based on the change in conductor cross-sectional area. Considering that the conductor warps, subsequent deformation processing based on resistance changes facilitates the determination of the relationship between impedance and warpage. A third functional relationship is determined based on the conductor resistivity formula and the initial resistance of the circuit board after warping. Based on these three functional relationships, a warpage model corresponding to the conductor impedance is determined, simplifying the warpage detection process. This solves the problem of inconsistent measurement standards and reduced accuracy caused by manual warpage detection in conventional technical solutions. The method achieves the technical effect of determining the actual warpage by relying on a model established by the conductor itself to establish the relationship between conductor impedance and warpage, thus improving accuracy and detection efficiency.

Description

Technical Field

[0001] This application relates to the field of circuit board manufacturing quality inspection technology, and in particular to a method for determining the warpage of a circuit board and an electronic device. Background Technology

[0002] In the lamination process of multilayer printed circuit boards (PCBs), considering the PCB's susceptibility to warping, excessive warping can lead to conductor deformation, causing impedance surges and resulting in poor contact between component leads and pads. Conventional warping detection involves manual measurement using a ruler. Key points on each PCB are selected, and the distance from the horizontal plane is measured using a ruler or height gauge to check for significant height differences, thus identifying warping. This manual inspection process is time-consuming, and the lack of strict standard measurement for distance from the horizontal plane reduces accuracy. Furthermore, it is time-consuming when inspecting multiple batches of PCBs.

[0003] Therefore, improving the accuracy and efficiency of PCB board conductor warpage detection is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] This application provides a method for determining the warpage of a circuit board and an electronic device, to at least solve the problem in the related art where the use of manual methods to detect warpage leads to inconsistent measurement standards and reduced accuracy.

[0005] This application provides a method for determining the warpage of a circuit board, including:

[0006] A first functional relationship is established based on the conductor length and warpage height of the circuit board conductors; and a second functional relationship is determined based on the change in conductor cross-sectional area.

[0007] The third function relationship of resistance change is determined based on the resistivity relationship of the conductor and the first resistance after the circuit board warps.

[0008] Based on the first, second, and third functional relationships, a warpage model corresponding to the conductor impedance is determined so that the impedance change value corresponding to the target conductor of the circuit board can be input into the warpage model to output the warpage of the target conductor.

[0009] This application also provides an electronic device, including: a memory for storing a computer program; and a processor for executing the computer program to implement the steps of any of the above-described methods for determining the warpage of a circuit board.

[0010] This application addresses the problem of inconsistent measurement standards and reduced accuracy caused by the manual detection of warpage in conventional technical solutions. First, a first functional relationship is established based on the conductor length and warpage height of the circuit board conductors. Under the assumption of small deformation, the circuit board warpage phenomenon can be approximated as a simply supported beam bending model, simplifying the complex nonlinear problem into a linear one. This simplifies the calculation process while ensuring the accuracy of the calculation results remains within engineering tolerances. A second functional relationship is determined based on the change in conductor cross-sectional area. Considering that the cross-sectional area changes after conductor warpage, leading to increased resistance, and that increased length also increases resistance, the change in conductor cross-sectional area is used to determine the corresponding functional relationship. This facilitates subsequent deformation processing based on resistance changes to determine the relationship between impedance and warpage. Second, a third functional relationship is determined based on the conductor resistivity relationship and the initial resistance after circuit board warpage. When conductor length increases and cross-sectional area decreases, resistance changes, forming a new third functional relationship, which facilitates subsequent deformation processing. Finally, based on the above three functional relationships, the warpage model corresponding to the conductor impedance is determined. Here, the above two functional relationships are substituted into the third functional relationship for transformation processing to obtain the conversion method between impedance and warpage. The measured impedance value is converted into warpage, simplifying the warpage detection process. Only the impedance change value at the time needs to be input into the model to know the actual value of warpage. This makes the warpage determination process uniform and automated, eliminating the need for manual horizontal comparison testing of each conductor. Starting from the conductor itself, it improves accuracy and real-time performance.

[0011] Therefore, it can solve the problem of inconsistent measurement standards and reduced accuracy caused by the use of manual methods to detect warpage in conventional technical solutions. It can achieve the technical effect of determining the actual warpage by relying on the model between the conductor impedance and warpage established by the conductor itself, thereby improving accuracy and detection efficiency. Attached Figure Description

[0012] To more clearly illustrate the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 A flowchart illustrating a method for determining the warpage of a circuit board, as provided in an embodiment of this application;

[0014] Figure 2This application provides a schematic diagram of wire bending corresponding to the occurrence of circuit board warping in an embodiment of the present application.

[0015] Figure 3 This is a schematic diagram of a circuit board edge through-hole provided in an embodiment of this application;

[0016] Figure 4 A schematic diagram of warpage under different batches provided in this application embodiment;

[0017] Figure 5 A flowchart of a warpage test provided in this application embodiment;

[0018] Figure 6 This is a structural diagram of a circuit board warpage determination device provided in an embodiment of this application. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of this application.

[0020] It should be noted that, in the description of this application, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. The terms "first," "second," etc., in this application are used to distinguish similar objects and are not used to describe a specific order or sequence.

[0021] To enable those skilled in the art to better understand the present application, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] In multilayer PCB lamination processes, circuit boards are prone to warping due to differences in the coefficients of thermal expansion between the substrate (such as FR-4) and the copper foil, uneven resin curing shrinkage, or residual mechanical stress. Excessive warping (typically required to be ≤0.5%) can lead to several problems, such as positioning errors in surface mount technology (SMT) pick-and-place machines, reduced yield, impedance abrupt changes in high-frequency signals caused by conductor deformation, resulting in reflections and crosstalk, poor contact between component leads and pads, and increased solder joint failure rate.

[0023] The conventional technical solution involves manually measuring the warp of a PCB at several key points (such as the four corners and the center) using a ruler or height gauge. The distance between these points and the horizontal plane is measured. If there is a significant height difference between the points, warp is indicated. These values ​​are manually recorded, and the degree of warp is then calculated. However, because PCB warp is inspected in batches, it is difficult to standardize measurement methods, and the inspection efficiency is slow.

[0024] The method for determining the warpage of a circuit board provided in this application can solve the above-mentioned technical problems.

[0025] Figure 1 A flowchart illustrating a method for determining the warpage of a circuit board, as provided in this application embodiment, is shown below. Figure 1 As shown, the method includes:

[0026] S11: Establish a first functional relationship based on the conductor length and warpage height of the circuit board conductors; and determine a second functional relationship based on the change in cross-sectional area of ​​the conductors;

[0027] S12: Determine the third functional relationship of resistance change based on the resistivity relationship of the conductor and the first resistance after the circuit board warps;

[0028] S13: Determine the warpage model corresponding to the conductor impedance based on the first functional relationship, the second functional relationship and the third functional relationship, so as to input the impedance change value corresponding to the target conductor of the circuit board into the warpage model, so as to output the warpage of the target conductor.

[0029] Specifically, when a circuit board warps, the conversion between physical deformation and electrical signals causes geometric deformation of the wires arranged on the circuit board, mainly changes in wire length and cross-sectional area. Based on this, step S11 takes into account the changes in these two situations and establishes corresponding functional relationships for each.

[0030] A first functional relationship is established based on the conductor length and warpage height of the circuit board conductors. This first functional relationship corresponds to the warpage deformation analysis. Under the assumption of small deformation, the circuit board warpage is approximated as a simply supported beam bending model. The circuit board is regarded as a simply supported beam, fixed at both ends, and subjected to a uniformly distributed load in the middle. Under small deformation, the bending of the beam can be approximated as elastic bending, satisfying Hooke's Law. The change in conductor length is defined by the mapping relationship between conductor length and warpage height.

[0031] The second functional relationship of cross-sectional area change is determined based on the change in conductor cross-sectional area. This change in cross-sectional area is caused by the Poisson effect; when the length and width of the conductor cross-section change, the area changes at a rate of twice the lateral strain. Therefore, the second functional relationship of cross-sectional area change is established.

[0032] The third functional relationship in step S12 takes into account the conductor resistivity relationship. middle, For resistance, Resistivity For the length of the conductor, Let be the cross-sectional area of ​​the conductor. The resistance of the conductor changes with its length and cross-sectional area; therefore, the degree of circuit board warping can be reflected by measuring the change in conductor resistance. Based on the conductor resistivity formula, the initial resistance after circuit board warping is calculated (…). To determine the third function relationship corresponding to the resistance change process, the settings are configured.

[0033] In step S13, based on the three functional relationships mentioned above, the first and second functional relationships are substituted into the third functional relationship. This substitution process allows for the derivation of the conversion method between conductor impedance and warpage, i.e., the warpage model corresponding to conductor impedance. In other words, through theoretical analysis of the conductor's deformation during warpage, the relationship between conductor length change and warpage height, as well as the relationship between resistance change and changes in conductor length and cross-sectional area, are established, thereby deriving a quantitative relationship model between resistance change and warpage.

[0034] It should be noted that during the establishment of the warpage model in steps S11 to S13 above, the historical conductor parameters corresponding to the circuit board can be used for training and derivation, which is not limited here. The number of training iterations and the selection of historical conductor parameters on a circuit board can be set according to the actual situation. In addition, the warpage model can also be trained with an artificial intelligence model to optimize and improve the model, enhance its adaptability and prediction accuracy, and realize intelligent prediction and early warning of circuit board warpage.

[0035] The target conductor on the circuit board is based on the conductor that needs to be tested during the actual testing process. By inputting the impedance change value, that is, the resistance change value of the target conductor, into the model, the warpage of the target conductor is obtained.

[0036] This application addresses the problem of inconsistent measurement standards and reduced accuracy caused by the manual detection of warpage in conventional technical solutions. First, a first functional relationship is established based on the conductor length and warpage height of the circuit board conductors. Under the assumption of small deformation, the circuit board warpage phenomenon can be approximated as a simply supported beam bending model, simplifying the complex nonlinear problem into a linear one. This simplifies the calculation process while ensuring the accuracy of the calculation results remains within engineering tolerances. A second functional relationship is determined based on the change in conductor cross-sectional area. Considering that the cross-sectional area changes after conductor warpage, leading to increased resistance, and that increased length also increases resistance, the change in conductor cross-sectional area is used to determine the corresponding functional relationship. This facilitates subsequent deformation processing based on resistance changes to determine the relationship between impedance and warpage. Second, a third functional relationship is determined based on the conductor resistivity relationship and the initial resistance after circuit board warpage. When conductor length increases and cross-sectional area decreases, resistance changes, forming a new third functional relationship, which facilitates subsequent deformation processing. Finally, based on the above three functional relationships, the warpage model corresponding to the conductor impedance is determined. Here, the above two functional relationships are substituted into the third functional relationship for transformation processing to obtain the conversion method between impedance and warpage. The measured impedance value is converted into warpage, simplifying the warpage detection process. Only the impedance change value at the time needs to be input into the model to know the actual value of warpage. This makes the warpage determination process uniform and automated, eliminating the need for manual horizontal comparison testing of each conductor. Starting from the conductor itself, it improves accuracy and real-time performance.

[0037] Therefore, it can solve the problem of inconsistent measurement standards and reduced accuracy caused by the use of manual methods to detect warpage in conventional technical solutions. It can achieve the technical effect of determining the actual warpage by relying on the model between the conductor impedance and warpage established by the conductor itself, thereby improving accuracy and detection efficiency.

[0038] In some embodiments, establishing a first functional relationship based on the wire length and warpage height of the circuit board conductors includes:

[0039] The integral formula for obtaining the arc length of a curve;

[0040] Taylor expansion is performed based on the integral formula for curve arc length to determine the deformed formula for curve arc length.

[0041] The conductor length and warping height are introduced based on the slope parameter in the curve arc length formula to establish the first functional relationship.

[0042] Specifically, the first functional relationship corresponds to the warping deformation analysis, under the assumption of small deformation. Figure 2 This application provides a schematic diagram of wire bending corresponding to a circuit board warping phenomenon, as shown in the embodiment of the present application. Figure 2 As shown, the warping of the circuit board is approximated by a simply supported beam bending model. The circuit board is regarded as a simply supported beam, with both ends fixed and the middle bearing a uniformly distributed load.

[0043] The integral formula for the arc length of a curve is: ;

[0044] In regular functions In the middle, I hope to be in When performing a Taylor expansion, the formula is: ;

[0045] Substituting the integral formula for the arc length of the curve into the arc length formula, we get: ;

[0046] The first integral in the above formula can be simply given as follows: Change, i.e., arc length is (Wire length) The second integral represents the result due to the slope The extra length caused, assuming It's a small amount; the extra length is equivalent to the total length. It is very small, and can be represented as ,in, for The maximum or average value of the arc length is the warping height. Therefore, the arc length can be approximated as: Here, higher-order terms are ignored. Therefore, the change in wire length is: That is, the first functional relationship.

[0047] The embodiment provides a simple beam bending model based on the relationship between the change in conductor length and the warping height, with the corresponding first functional relationship simplifying the complex nonlinear problem into a linear problem, reducing the computational difficulty, and ensuring that the accuracy of the calculation results is within the allowable range of engineering.

[0048] In some embodiments, determining a second functional relationship of cross-sectional area change based on the change in conductor cross-sectional area includes:

[0049] When the conductor length changes to the first conductor length after the conductor warps, the transverse strain of the conductor is determined based on Poisson's ratio;

[0050] The rate of change of the cross-sectional area of ​​the conductor is determined based on the transverse strain;

[0051] The second functional relationship of the cross-sectional area change is determined by transforming the cross-sectional area change rate.

[0052] Specifically, Poisson's ratio is an important mechanical property parameter of materials, representing the ratio of lateral strain to axial strain when a material is subjected to axial tension or compression. When a conductor is subjected to axial tension, its length increases while it contracts laterally; conversely, when a conductor is subjected to axial compression, its length decreases while it expands laterally.

[0053] When the conductor length changes, it becomes the first conductor length after warping, and the change is... The rate of change At that time, the lateral strain of the conductor is , here It represents Poisson's ratio.

[0054] For the conductor cross-section, it can be circular or rectangular. If the conductor has a rectangular cross-section, both the length and width change, and its area changes at approximately twice the lateral strain. That is, the rate of change of the conductor's cross-sectional area is: ; For the cross-sectional area, The change in cross-sectional area is the amount of change; the rate of change in cross-sectional area is transformed to determine the second functional relationship of the change in cross-sectional area, i.e. .because The resistance decreases as the area changes, and the resistance also increases as the length increases.

[0055] The second functional relationship determined by the derivation of the cross-sectional area change provided in this embodiment shows that as the circuit board warps, its cross-sectional area changes, which in turn affects the resistance of the wires. This allows the degree of warping of the circuit board to be directly reflected by measuring the resistance change of the wires, and also facilitates the establishment of a warping model.

[0056] In some embodiments, a third functional relationship for the resistance change is determined based on the resistivity relationship of the conductor and the first resistance after the circuit board warps, including:

[0057] When the circuit board warps, the third function relationship is determined based on the conductor resistivity relationship, the cross-sectional area of ​​the warped conductor, the conductor length, and the length of the first conductor after warping.

[0058] Specifically, the resistivity relationship of the conductor is as follows: :in, Resistivity For the length of the conductor, This refers to the cross-sectional area of ​​the conductor; as the length increases... Cross-sectional area reduced When the circuit board warps, the third functional relationship of the resistance change corresponding to the first resistor is: ;in, This represents the cross-sectional area of ​​the conductor after warping. For the length of the conductor, This is the length of the first conductor after it warps.

[0059] In this embodiment, when the circuit board warps, deformation processing is performed based on the conductor resistivity relationship. Combined with the changes in conductor length and cross-sectional area, a third function relationship after the resistance change is formed. This further reflects the degree of warping of the circuit board from the conductor resistance, which is convenient for subsequent derivation of the warping model.

[0060] In some embodiments, determining the warpage model corresponding to the conductor impedance based on a first functional relationship, a second functional relationship, and a third functional relationship includes:

[0061] The first relationship for determining the cross-sectional area of ​​the conductor after warping is based on the sum of the cross-sectional area before warping and the change in cross-sectional area.

[0062] Substitute the first relationship of conductor cross-sectional area and the second functional relationship of cross-sectional area change into the third functional relationship to determine the fourth functional relationship;

[0063] In the fourth functional relationship, the conductor length and conductor cross-sectional area are extracted as common divisors according to the conductor resistivity relationship to determine the fifth functional relationship;

[0064] Substitute the first functional relationship and the warp relationship into the fifth functional relationship to determine the warp model corresponding to the conductor impedance.

[0065] Specifically, the first relation is: ;in, This represents the cross-sectional area of ​​the conductor before warping. This represents the change in cross-sectional area.

[0066] Substituting the first relationship and the second functional relationship of cross-sectional area change mentioned above into the third functional relationship, the determined fourth functional relationship is as follows:

[0067] ;

[0068] In the fourth functional relationship mentioned above, the fifth functional relationship is determined by extracting the conductor length and conductor cross-sectional area as common divisors based on the conductor resistivity relationship:

[0069] ;

[0070] ;

[0071] Substituting the first functional relationship and the warpage relationship into the fifth functional relationship, where the warpage relationship is: The first functional relationship is: Substituting this into the equation, we can obtain the following formula for the warpage model: . It is a calibration coefficient, determined by experimental fitting using a calibration plate with known warpage.

[0072] The derivation process of the warpage model provided in this embodiment is to derive a quantitative relationship model between resistance change and warpage by combining the impedance value of the conductor with the relationship between resistance change and conductor length and cross-sectional area change, thereby realizing high-precision quantitative analysis of circuit board warpage.

[0073] In some embodiments, in the fourth functional relationship, the conductor length and conductor cross-sectional area are extracted as common divisors according to the conductor resistivity relationship to determine the fifth functional relationship, including:

[0074] The extracted common divisor and wire length are used as the second relationship corresponding to the second resistance before warping occurs;

[0075] Ignore the higher-order terms in the second relation to determine the fifth functional relation corresponding to the rate of change of resistance.

[0076] Specifically, in the process of constructing the fifth functional relationship, the extracted common divisor and the wire length are used as the second relationship corresponding to the second resistance before warping occurs. The specific formula is as follows: Expand the above relation and ignore the higher-order minterms in the second relation to obtain the fifth functional relation.

[0077] This embodiment, by ignoring higher-order terms, allows us to determine the fifth functional relationship corresponding to the rate of change of resistance. This enables us to focus only on the terms that have the greatest impact on the result, while ignoring higher-order terms with less influence. This simplifies the calculation process while still obtaining sufficiently accurate results. Considering that precise calculations require significant computational resources, approximate calculations can achieve results quickly with limited resources.

[0078] In some embodiments, after determining the warp of the target conductor, the method further includes:

[0079] Get the preset warp;

[0080] If the warp of the target conductor is greater than the preset warp, then the warp of the target conductor is determined to be unqualified.

[0081] If the warp of the target conductor is less than or equal to the preset warp, then the warp of the target conductor is deemed to be qualified.

[0082] Correspondingly, when the warpage of the target conductor is unqualified, the method also includes:

[0083] The target level range exceeding the preset warp is determined based on the difference between the warp of the target conductor and the preset warp.

[0084] When the target level range is the first level range, manually bend the target conductor so that it bends in the opposite direction;

[0085] When the target grade range is the second grade range, the target lead is fixed on the straightening machine, and the straightening pressure and straightening speed of the straightening machine are adjusted according to the lead material, size and warpage for straightening treatment; wherein, the first grade range is smaller than the second grade range;

[0086] Alternatively, the target wire can be heated to a target temperature based on its wire material, and then stretched while heated.

[0087] After the warp is detected, the warp of the target conductor is output and compared with the preset warp. If the warp is greater than the preset warp, the target conductor is considered unqualified and requires correction. This correction can be done manually, mechanically, or through heat treatment.

[0088] When the difference between the warp of the target conductor and the preset warp is within the first level range, it means that the warp exceeds the range by a small amount. Manually bend the target conductor in the opposite direction. For some slightly bent thin conductors, their shape can be adjusted by gently bending them by hand until the conductor reaches the required straightness.

[0089] When the difference between the target conductor's warp and the preset warp is within the second-level range, it indicates that the warp exceeds the limit significantly, requiring mechanical correction. The conductor is fixed to a straightening machine, and the machine's parameters, such as straightening pressure and speed, are adjusted according to the conductor's material, size, and degree of warp. During mechanical straightening, the accuracy and stability of the straightening equipment must be ensured. Excessive straightening pressure or speed may cause scratches, indentations, or even breakage of the conductor.

[0090] The aforementioned manual and mechanical straightening methods both employ physical adjustments. This application can also utilize heat treatment methods, such as thermal stretching. Wire warping is caused by uneven local dimensions or irregular shapes; thermal stretching can be used to adjust the wire's shape. For example, some wires that have undergone welding or partial processing may exhibit irregular shapes and warping. First, the wire is heated to a certain temperature, determined based on the wire's material. Then, the wire is stretched while heated, with a moderate stretching force, generally 30%-50% of the wire's yield strength. Stretching can adjust the wire's shape and reduce warping. During thermal stretching, it is crucial to ensure uniform heating and avoid localized overheating or cooling. Simultaneously, the stretching speed must be appropriately controlled; excessively fast stretching may cause wire breakage, while excessively slow stretching will affect production efficiency.

[0091] The warpage correction process provided in this embodiment indicates that the warpage is unqualified and requires correction if the warpage is greater than the preset warpage, in order to ensure the quality and performance of the conductor.

[0092] In some embodiments, the process of determining circuit board conductors includes:

[0093] Determine the threshold range for conductor width and the threshold range for conductor thickness;

[0094] The circuit board conductors are filtered based on the conductor width threshold range and the conductor thickness threshold range to obtain the circuit board conductors. The conductor width and the conductor thickness are both within the conductor width threshold range.

[0095] Specifically, Figure 3 This is a schematic diagram of a circuit board edge through-hole provided in an embodiment of this application, such as... Figure 3 As shown, metallized vias (A, B, C, D) are symmetrically positioned along the edge of the circuit board. The via diameter is 0.5-1.0 mm, a size that facilitates measurement of conductivity without occupying excessive space. Conductors are arranged along the warp-sensitive direction (e.g., the long side) to maximize the effect of length variation. Screening is performed on the conductor width and thickness design to ensure both the conductor's guidance and mechanical strength, while also guaranteeing the accuracy of the subsequently derived warp model.

[0096] For example, the line width should be set to 0.5-1mm (preferably 0.8mm). The choice of line width directly affects the resistance and mechanical properties of the conductor. If the line width is too narrow (less than 0.5mm), the resistance of the conductor will increase, thus reducing the measurement sensitivity. If the line width is too wide (greater than 1mm), although it can reduce resistance and increase mechanical strength, it will occupy more space on the circuit board. A line width of 0.8mm is preferred, achieving the optimal balance between measurement sensitivity and circuit layout. Line thickness... (1oz copper) The choice of wire thickness mainly considers the conductivity and mechanical properties of the conductor. A 1oz copper wire thickness is a standard thickness commonly used in PCB manufacturing. It has good conductivity and mechanical strength. This thickness of copper foil can ensure that the resistance of the wire is low enough and can withstand a certain amount of mechanical stress during the warping of the circuit board.

[0097] In this embodiment, the selection criteria for circuit board conductors and the setting of line width and line thickness during the establishment of the warp model are provided to ensure that the conductor resistance and mechanical properties are not affected, improve the sensitivity during the measurement process, and ensure the balance with the circuit layout.

[0098] In some embodiments, after determining the warp of the target conductor, the method further includes:

[0099] Get the preset warp;

[0100] If the warp of the target conductor is greater than the preset warp, then the warp of the target conductor is determined to be unqualified.

[0101] The number of qualified warpages corresponding to multiple conductors in the target circuit board where the target conductor is located is counted.

[0102] If the number of acceptable warpages is less than the preset acceptable number, the target circuit board is determined to be unacceptable.

[0103] The target circuit board is marked to determine the pass rate of the target batch corresponding to the target circuit board;

[0104] When the pass rate is less than the preset pass rate, the wire material corresponding to the target batch is adjusted.

[0105] Return to the step of inputting the impedance change value corresponding to the target conductor of the circuit board into the warpage model, so as to determine the corresponding warpage based on the impedance change value of the target conductor corresponding to the adjusted circuit board material.

[0106] Specifically, based on the above embodiments, regarding the warpage acceptance test of the target conductor, it can be seen that the target conductor is located on a circuit board. Since the circuit board undergoes batch testing during the design process, simply testing the target conductor alone will not fundamentally address the correction of corresponding parameters or process operations during the circuit board design. Therefore, this embodiment needs to statistically analyze the testing status of other conductors on the target circuit board corresponding to the target conductor, that is, to count the number of conductors on the target circuit board corresponding to the target conductor that have passed warpage acceptance. If the number of conductors passing warpage acceptance is less than a preset number, the target circuit board is determined to be unqualified. This target circuit board is then marked to determine the pass rate for the target batch corresponding to the target circuit board.

[0107] If the pass rate is lower than the preset pass rate, it indicates that the circuit board design for this batch generally suffers from wire warping defects, suggesting a potential problem with the wire material. The wire material needs to be adjusted, and then the circuit should be retested.

[0108] This embodiment extends the warp detection from a single target conductor to the corresponding warp detection throughout the entire batch of circuit board design processes, thereby reducing the number of non-compliant warp detections during the design process and improving the quality of the circuit boards.

[0109] In some embodiments, before determining the third functional relationship of resistance change based on the conductor resistivity relationship and the first resistance after the circuit board warps, the method further includes:

[0110] Determine the ambient temperature of the circuit board conductors;

[0111] The resistivity corresponding to the ambient temperature is determined based on the ambient temperature, reference temperature, and temperature coefficient to complete the resistivity correction process.

[0112] Substitute the resistivity corresponding to the ambient temperature into the wire resistivity formula to proceed to the third functional relationship of determining the resistance change based on the wire resistivity formula and the first resistance after the circuit board warps.

[0113] Specifically, in practical applications, the calculated resistivity of the conductor is dynamically adjusted based on changes in ambient temperature to more accurately reflect the actual resistance of the conductor at the current temperature. This is because the resistivity of the conductor changes with temperature, and this change is significant in many engineering applications. The resistivity of the conductor (… Resistivity is an important physical parameter that represents the resistance per unit length and unit cross-sectional area of ​​a conductor under specific conditions. The resistivity of a conductor typically changes with temperature. For most metallic conductors, resistivity increases with increasing temperature. This relationship can be expressed by the following formula, which represents the correction for resistivity: ;

[0114] in, To be in ambient temperature The resistivity below, To be at the reference temperature The resistivity below, is the temperature coefficient, representing the rate at which resistivity changes with temperature; The current ambient temperature. This is a reference temperature.

[0115] By applying the resistivity corresponding to the ambient temperature to the conductor resistivity relationship in the above embodiment, a third function relationship corresponding to the real-time change is obtained.

[0116] The resistance of the conductor provided in this embodiment is affected by ambient temperature. If temperature changes are not considered and the resistivity at a reference temperature is used directly to calculate the resistance, measurement errors may occur. Real-time correction can more accurately reflect the actual resistance value of the conductor at the current temperature, improving both measurement accuracy and the accuracy of warpage detection.

[0117] In some embodiments, the batch measurement process for impedance measurement involves measuring the impedance value of the conductors between AB or CD vias on the circuit board after each batch of circuit boards is laminated, and transmitting the values ​​to a computer program. The specific implementation steps are as follows:

[0118] Selection of measuring equipment: A high-precision impedance analyzer is used for measurement, which can meet the accuracy requirements of impedance measurement in this application.

[0119] Measurement point selection: The conductors between vias AB or CD are chosen as measurement points because these vias are symmetrically positioned at the edge of the circuit board, and the conductors, arranged along the warp-sensitive direction, can maximize the reflection of the circuit board's warp degree. Furthermore, regarding the selection of the target conductors, at least one pair of vias are placed on the circuit board surface, and connected by conductors to form a closed loop. By appropriately selecting the position and size of the vias and the arrangement direction and parameters of the conductors, the function of converting the physical warp deformation of the circuit board into changes in electrical signals (impedance) is achieved.

[0120] Data transmission method: The measured impedance value is transmitted to the computer program in real time via Universal Serial Bus (USB) or network interface to ensure the accuracy and real-time performance of data transmission.

[0121] The program uses an impedance-warping theory model to display the values ​​of each batch through a line graph, and issues an alert for values ​​exceeding the warping threshold. The specific implementation process is as follows:

[0122] Data processing algorithm: The computer program has a built-in impedance-warpage conversion algorithm, based on a pre-established model. The measured impedance value is converted into warpage. This algorithm uses digital signal processing techniques such as Fast Fourier Transform (FFT) to filter and reduce noise in the impedance data, improving the accuracy of the data.

[0123] Line chart display: The warpage data of each batch is displayed on the computer screen in the form of a line chart, with the Y-axis representing the warpage (%) and the X-axis representing the batch. Figure 4This application provides a schematic diagram of warpage under different batches as an embodiment of the present application. Figure 4 As shown, the line graph allows for a direct observation of the warpage trend of each batch of circuit boards, facilitating timely problem detection by production managers.

[0124] Early warning mechanism: A warpage threshold of 0.5% is set. When the warpage of a batch of circuit boards exceeds this threshold, the system automatically issues an early warning signal, such as an audible alarm or screen flashing, and records relevant information for that batch, including production time and equipment parameters, providing a basis for subsequent process adjustments. It can detect the warpage of each batch of circuit boards in real time and issue timely warnings when the warpage exceeds the standard, enabling production personnel to quickly take measures to adjust the production process, avoid mass production of defective products, and improve production efficiency and product quality. Compared to traditional offline inspection methods, the real-time inspection function of this application can reduce the inspection time from several hours to several minutes, greatly improving production efficiency.

[0125] Figure 5 A flowchart of a warpage test provided for an embodiment of this application is shown below. Figure 5 As shown, the circuit board has a via layout. The impedance of the target conductors on the circuit board is measured, and the actual warpage is output through the impedance-warpage model and presented by the program.

[0126] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods according to the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method.

[0127] Embodiments of this application also provide a device for determining the warpage of a circuit board. Figure 6 A structural diagram of a circuit board warpage determination device provided in an embodiment of this application is shown below. Figure 6 As shown, the device includes:

[0128] Module 11 is established to establish a first functional relationship based on the conductor length and warpage height of the circuit board conductors; and to determine a second functional relationship based on the change in cross-sectional area of ​​the conductors.

[0129] The first determining module 12 is used to determine the third functional relationship of resistance change based on the resistivity relationship of the wire and the first resistance after the circuit board warps.

[0130] The second determining module 13 is used to determine the warpage model corresponding to the conductor impedance based on the first functional relationship, the second functional relationship and the third functional relationship, so as to input the impedance change value corresponding to the target conductor of the circuit board into the warpage model and output the warpage of the target conductor.

[0131] For any omitted virtual device claims, the description should be expanded to correspond one-to-one with the method claims.

[0132] For a description of the features in the embodiment corresponding to the circuit board warpage determination device, please refer to the relevant description in the embodiment corresponding to the circuit board warpage determination method, which will not be repeated here.

[0133] Embodiments of this application also provide an electronic device, including a memory and a processor, wherein the memory stores a computer program and the processor is configured to run the computer program to perform the steps in any of the above embodiments of the method for determining the warpage of a circuit board.

[0134] Embodiments of this application also provide a computer-readable storage medium storing a computer program, wherein the computer program is configured to execute the steps in any of the above embodiments of the method for determining the warpage of a circuit board when it is run.

[0135] In one exemplary embodiment, the aforementioned computer-readable storage medium may include, but is not limited to, various media capable of storing computer programs, such as a USB flash drive, read-only memory (ROM), random access memory (RAM), portable hard disk, magnetic disk, or optical disk.

[0136] Embodiments of this application also provide a computer program product, which includes a computer program that, when executed by a processor, implements the steps in any of the above embodiments of the method for determining the warpage of a circuit board.

[0137] Embodiments of this application also provide another computer program product, including a non-volatile computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps in any of the above embodiments of the method for determining the warpage of a circuit board.

[0138] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0139] The foregoing has provided a detailed description of a method for determining the warpage of a circuit board and an electronic device provided in this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only intended to help understand the method and core ideas of this application. It should be noted that those skilled in the art can make various improvements and modifications to this application without departing from its principles, and these improvements and modifications also fall within the protection scope of this application.

Claims

1. A method for determining the warpage of a circuit board, characterized in that, include: A first functional relationship is established based on the wire length and warpage height of the circuit board conductors; And determine the second functional relationship of the cross-sectional area change based on the change in the conductor's cross-sectional area; wherein, the first functional relationship is: ; For the length of the conductor, The warpage height is given. The process of establishing the first functional relationship is as follows: Obtain the integral formula for the curve arc length; perform Taylor expansion based on the integral formula for the curve arc length to determine the deformed curve arc length formula; introduce the conductor length and warpage height according to the slope parameter in the curve arc length formula to establish the second functional relationship: ; Poisson's ratio, For the cross-sectional area, The change in cross-sectional area is the amount of change. The process of establishing the second functional relationship is as follows: when the conductor length changes to the first conductor length after the conductor warps, the transverse strain of the conductor is determined based on Poisson's ratio; the rate of change of the cross-sectional area of ​​the conductor is determined based on the transverse strain; the second functional relationship of the change in cross-sectional area is determined by conversion processing based on the rate of change in cross-sectional area. The third functional relationship of resistance change is determined based on the resistivity relationship of the conductor and the initial resistance after the circuit board warps; the third functional relationship is: ; This represents the cross-sectional area of ​​the conductor after warping. For the length of the conductor, The length of the first conductor after the conductor warps; Based on the first functional relationship, the second functional relationship, and the third functional relationship, a warpage model corresponding to the conductor impedance is determined so that the impedance change value corresponding to the target conductor of the circuit board can be input into the warpage model to output the warpage of the target conductor. Correspondingly, the warpage model corresponding to the conductor impedance is determined based on the first functional relationship, the second functional relationship, and the third functional relationship, including: A first relationship is determined based on the sum of the conductor cross-sectional area before warping and the change in cross-sectional area; wherein, the first relationship is: ; Substituting the first relationship of conductor cross-sectional area and the second functional relationship of cross-sectional area change into the third functional relationship, a fourth functional relationship is determined; wherein, the fourth functional relationship is: ; In the fourth functional relationship, the conductor length and conductor cross-sectional area are extracted as common divisors based on the conductor resistivity relationship to determine the fifth functional relationship; specifically, the extracted common divisors and conductor length are used as the second relationship corresponding to the second resistance before warping. After expansion, higher-order terms are ignored to determine the fifth functional relationship, specifically: ; ; Substituting the first functional relationship and the warpage relationship into the fifth functional relationship, the warpage model corresponding to the conductor impedance is determined; wherein, the warpage relationship is as follows: The relationship for the warpage model is: , It is a calibration coefficient, determined by experimental fitting using a calibration plate with known warpage.

2. The method for determining the warpage of a circuit board according to claim 1, characterized in that, After determining the warp of the target conductor, the following steps are also included: Get the preset warp; If the warpage of the target conductor is greater than the preset warpage, then the warpage of the target conductor is determined to be unqualified. If the warp of the target conductor is less than or equal to the preset warp, then the warp of the target conductor is determined to be qualified. Correspondingly, when the warpage of the target conductor is unqualified, the method further includes: The target level range exceeding the preset warp is determined based on the difference between the warp of the target conductor and the preset warp. When the target level range is the first level range, the target wire is manually bent so that the target wire is bent in the opposite direction. When the target grade range is the second grade range, the target wire is fixed on the straightening machine, and the straightening pressure and straightening speed of the straightening machine are adjusted according to the wire material, size and warpage for straightening treatment; wherein, the first grade range is smaller than the second grade range; Alternatively, the target wire can be heated to a target temperature according to its wire material, and then stretched while heated.

3. The method for determining the warpage of a circuit board according to claim 1, characterized in that, The process of determining circuit board conductors includes: Determine the threshold range for conductor width and the threshold range for conductor thickness; The circuit board conductors are filtered based on the conductor width threshold range and the conductor thickness threshold range to obtain the circuit board conductors, wherein the conductor width is within the conductor width threshold range and the conductor thickness is within the conductor thickness threshold range.

4. The method for determining the warpage of a circuit board according to claim 1, characterized in that, After determining the warp of the target conductor, the following steps are also included: Get the preset warp; If the warpage of the target conductor is greater than the preset warpage, then the warpage of the target conductor is determined to be unqualified. The number of qualified warpages corresponding to multiple conductors in the target circuit board where the target conductor is located is counted. If the number of acceptable warpages is less than the preset acceptable number, then the target circuit board is determined to be unacceptable. The target circuit board is marked in order to determine the pass rate of the target batch corresponding to the target circuit board. When the pass rate is less than the preset pass rate, the material of the wire corresponding to the target batch is adjusted. Returning to the step of inputting the impedance change value corresponding to the target conductor of the circuit board into the warpage model, the warpage is determined by the impedance change value of the target conductor corresponding to the adjusted circuit board material.

5. An electronic device, characterized in that, include: Memory, used to store computer programs; A processor, configured to implement the steps of the method for determining the warpage of a circuit board as described in any one of claims 1 to 4 when executing the computer program.

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