Circuit board component misplacement and polarity reverse connection detection method and device based on electrical performance parameters

Abstract

This application relates to a method and apparatus for detecting mis-assembly and reverse polarity of circuit board components based on electrical performance parameters. The method includes: applying an excitation signal to the location of the component under test and acquiring the electrical response; extracting harmonic components generated by the nonlinear transmission characteristics of the component from the electrical response; determining whether the component has linear or nonlinear properties based on the presence or absence of the harmonic components, and comparing it with the expected properties of the component to be installed at the location; comparing the phase of the even-order harmonic components with a reference phase to determine the polarity orientation; and determining the location status as normal, mis-assembly, reverse polarity, or missing component based on the electrical response, the property comparison result, and the polarity orientation. This application can distinguish four types of assembly states of the location from the in-circuit electrical response before the circuit board is powered on, avoiding damage to components with reverse polarity upon power-on.

Description

Technical Field

[0001] This application relates to the field of circuit board testing, and in particular to a method and apparatus for detecting mis-assembly and reverse polarity of circuit board components based on electrical performance parameters. Background Technology

[0002] The assembly quality of a circuit board determines the functionality and reliability of an electronic product. In surface mount and through-hole mounting processes, the components on the circuit board must be assembled according to design requirements. The type, parameters, and polarity orientation of the components must all match the design intent of the component placement. In mass production, components may be missing, components of the wrong type or with incorrect parameters may be assembled, or polarity may be reversed on polarity-sensitive components such as electrolytic capacitors and diodes. These assembly defects will cause the circuit board to deviate from its intended electrical function.

[0003] Among the aforementioned defects, reverse polarity can also damage the components themselves. Electrolytic capacitors, tantalum capacitors, and other polarity-sensitive components will be damaged within a short time when powered on with reverse polarity, potentially triggering cascading failures. Therefore, checking the assembly status of components before powering on the circuit board, distinguishing between normal, incorrectly assembled, reversed polarity, and missing components, and deciding whether to allow power-on accordingly, can reduce component damage and circuit board rework.

[0004] Existing detection methods struggle to identify specific defect types in component locations from electrical parameters before power-on. Machine vision-based identification of component appearance and silkscreen printing relies on visible markings, making it impossible to determine polarity for locations with missing or obscured markings. Methods that collect electrical parameters such as rectified filter voltage, casing leakage voltage, or branch current rely on comparing a single parameter to an expected range, providing only a binary conclusion of pass or fail. Since the characteristics of misassembly, reverse polarity, and missing components overlap on a single electrical parameter, these methods cannot identify the defect type even if an abnormality is detected. Misassembly locations falling within the legal range of replacement material widths are often treated as normal and allowed to proceed. Furthermore, since this data collection occurs after the circuit board is powered on, it cannot provide pre-power-on protection for reverse polarity locations. Methods that use nonlinear intermodulation or harmonic characteristics to determine component degradation or polarity still only provide a binary conclusion of parameter degradation or correct polarity, failing to differentiate between normal, misassembly, reverse polarity, and missing components as parallel component statuses within the same process. Summary of the Invention

[0005] In order to identify the specific defect type of the component position from the in-circuit electrical parameters before the circuit board is powered on, and to distinguish normal, misassembled, reverse polarity, and missing components as parallel component position states, this application provides a method and apparatus for detecting misassembled and reverse polarity of circuit board components based on electrical performance parameters.

[0006] Firstly, this application provides a method for detecting incorrect assembly and reverse polarity of circuit board components based on electrical performance parameters, employing the following technical solution: A method for detecting incorrect assembly and reverse polarity of circuit board components based on electrical performance parameters includes the following steps: S1. Apply an excitation signal to the material level where the component under test is located on the circuit board, collect the electrical response of the material level to the excitation signal, and extract the harmonic components generated by the nonlinear transmission characteristics of the component under test from the electrical response. The harmonic components include even harmonic components. S2. Based on the presence or absence of harmonic components, determine whether the component under test has linear or nonlinear properties, and compare the linear or nonlinear properties with the expected properties of the components to be installed at the material level to obtain the property comparison results. S3. Compare the phase of the even harmonic component with the reference phase. The reference phase is the phase of the even harmonic component of the component to be installed under the correct polarity orientation. Determine the polarity orientation of the component under test based on whether the phase of the even harmonic component is reversed relative to the reference phase. S4. Based on the electrical response, attribute comparison results, and polarity orientation, determine the material level status of the component under test. The material level status is one of the following: normal, incorrectly assembled, reversed polarity, or missing. Specifically, if the electrical response is lower than the expected response threshold of the material level, the material level status is determined to be missing. If the electrical response is not lower than the expected response threshold, further determination is made based on the attribute comparison results and polarity orientation: if the attribute comparison results indicate inconsistent attributes, the material level status is determined to be incorrectly assembled; if the attribute comparison results indicate consistent attributes and reversed polarity, the material level status is determined to be reversed polarity; if the attribute comparison results indicate consistent attributes and positive polarity, the material level status is determined to be normal.

[0007] By adopting the above technical solution, the electrical response of the material level to the excitation signal is used as a unified observation. The presence or absence of harmonic components is mapped to the linear or nonlinear properties of the components. The polarity orientation is characterized by the reversal of the even-order harmonic components relative to the reference phase. This allows the attribute comparison results and polarity orientation to be combined with the electrical response amplitude in the same process, converging the material level status into one of the following categories: normal, mis-installed, reversed polarity, and missing. Missing is first separated by whether the electrical response is lower than the expected response threshold, then mis-installed is separated by whether the attributes are consistent, and finally, reversed polarity is distinguished from normal by whether the polarity is reversed. This allows the three types of defects to be identified step by step by two relatively independent observations: harmonic properties and even-order phase, even when they are mixed on a single electrical parameter. The phase discrimination of even-order harmonic components is based on the premise that the component under test has nonlinear properties.

[0008] Optionally, in S3, the reference phase is determined by the even harmonic component of the corresponding position of the good sample or gold plate of the component to be installed under the correct polarity orientation; the polarity orientation is determined to be reversed in response to the phase reversal of the even harmonic component of the component under test relative to the reference phase; while the phase of the even harmonic component reverses relative to the reference phase, the phase of the odd harmonic component in the electrical response remains unchanged relative to the phase of the odd harmonic component of the corresponding component as a cross-verification that the polarity orientation is reversed.

[0009] By adopting the above technical solution, the reference phase is determined by a good sample or a gold plate, and the mutual verification of the unchanged phase of odd harmonics and the reversal of even harmonics is used as a cross-verification for reverse determination, so that the determination of polarity orientation can be independently verified when even phase is susceptible to interference from parallel networks.

[0010] Optionally, for the device under test (DUT) that exhibits nonlinear properties and is an electrolytic capacitor or tantalum capacitor, a DC bias is applied to the DUT and the transient leakage current characteristics of the DUT are collected. The evolution of the transient leakage current characteristics over time is used as an absolute polarity indicator. The absolute polarity indicator is cross-checked with the polarity orientation to determine the material level status.

[0011] By adopting the above technical solution, an absolute polarity indication of the transient leakage current evolution over time is introduced for electrolytic capacitors and tantalum capacitors, so that polarity criteria independent of the reference phase can still be obtained when even-order phase evidence is insufficient.

[0012] Optionally, S1 to S4 are executed in the passive phase before the circuit board is powered on, and the amplitude of the excitation signal is lower than the threshold that would damage the device under test with reverse polarity; in response to the material level being determined to be reverse polarity, the circuit board is prohibited from being powered on; in response to the material level being determined to be normal, the circuit board is allowed to be powered on.

[0013] By adopting the above technical solution, the detection is placed in a passive stage before power-on and the excitation amplitude is limited to below the damage threshold, so that the polarity reversed material level is prohibited from being powered on after the judgment, thus avoiding damage to the device during live detection.

[0014] Optionally, in S4, a consistency decision is made between the attribute comparison result and the polarity orientation. In response to a conflict between the attribute comparison result and the polarity orientation, it is determined that there is a decision ambiguity. In response to the existence of decision ambiguity, the material status of ...

[0015] By adopting the above technical solution, the conflict between the attribute comparison result and the polarity orientation is marked as a decision ambiguity, and the ambiguity is eliminated by constraining other material levels in the same network or increasing the excitation amplitude for retesting, so that the material level status is not arbitrarily determined when there is a conflict of evidence.

[0016] Optionally, before the consistency decision, the electrical response of the material position is differentially compared with the electrical response of the corresponding material position on the gold plate to obtain the differential residual. The layout of the gold plate and the circuit board are the same. The differential residual of the reference component on the circuit board that is the same type as the component under test is used as the relative benchmark. The components under test that deviate from the relative benchmark are considered as candidates for misassembly or reverse polarity connection and participate in the consistency decision.

[0017] By adopting the above technical solution, the differential residual of the same type of reference component is used as a relative benchmark to screen deviation candidates, so that candidates with incorrect assembly or reverse polarity are screened before entering the decision-making process. Figure 1 The gold plate differential constraint is achieved.

[0018] Optionally, the excitation signal includes a frequency sweep signal applied at multiple frequencies, and the material level status is determined jointly based on the electrical response of the component under test at multiple frequencies.

[0019] By adopting the above technical solution, joint determination is made at multiple frequencies, which makes it difficult to distinguish attributes and polarity differences at a single frequency, thus supplementing them in the frequency dimension.

[0020] Optionally, the excitation signal is one of a bipolar pulse, a step wave, or a two-tone signal, and the harmonic components and polarity information are obtained simultaneously through the electrical response of a single excitation.

[0021] By adopting the above technical solution, harmonic and polarity information can be obtained simultaneously with a single shaping excitation, thereby shortening the detection cycle.

[0022] Optionally, the excitation signal is a two-tone signal consisting of two single tones with a non-integer harmonic relationship, and even harmonic components are extracted from the intermodulation components of the electrical response.

[0023] By adopting the above technical solution, even harmonics are extracted from the intermodulation components of non-integer multiples of the two tones, thus separating the even components from the excitation fundamental frequency.

[0024] Optionally, the device under test can be distinguished as a linear device, a device containing a PN junction, or a device containing a magnetic core based on the relative magnitudes of the second and third harmonic components in the electrical response.

[0025] By adopting the above technical solution, the relative magnitude of the second and third harmonics can be used to distinguish the types of components, making it possible to differentiate between linear components, components with PN junctions, and components with magnetic cores.

[0026] Optionally, the even harmonic component is taken as the second harmonic component. In response to the phase reversal of the second harmonic component relative to the reference phase, the polarity orientation is determined to be reversed.

[0027] By adopting the above technical solution, even harmonics are taken as second harmonics and their phase reversal is used to determine the reversal, so that the polarity criterion falls on the low-order components with higher signal-to-noise ratio.

[0028] Optionally, the differential residual is divided into harmonic residual and impedance residual. The harmonic residual is taken for the device under test with nonlinear properties, and the impedance residual is taken for the device under test with linear properties.

[0029] By adopting the above technical solution, harmonic residuals are taken for nonlinear components and impedance residuals are taken for linear components, so that the differential residuals match the properties of the components.

[0030] Optionally, multiple diodes in the bridge rectifier, multiple capacitors in parallel bypass, or two transistors in the differential pair can be selected as reference components.

[0031] By adopting the above technical solution, the reference component can be taken from the bridge rectifier, parallel capacitor or differential pair, making it feasible for the same type of self-reference in various packages.

[0032] Optionally, for multiple components under test that are in the same local circuit and of the same type, the harmonic components of each component under test can be directly compared and the components under test that deviate from the group can be used as candidates, without the need for gold plate differential.

[0033] By adopting the above technical solution, harmonic outliers can be directly compared between similar components in the same local circuit, so that abnormal material levels can still be identified even when there is no gold plate.

[0034] Optionally, in response to the absence of outliers among similar reference components, the case of suspected batches of reverse-connected components is switched to be determined by the absolute polarity indication of the phase of even-order harmonic components or transient leakage characteristics.

[0035] By adopting the above technical solution, when there are no outliers in the reference parts, the absolute polarity indicator is switched to ensure that the entire batch of reverse polarity connections are not missed.

[0036] Optionally, the criterion for transient leakage current characteristics can be the slope of the leakage current increase over time, or the ratio of the transient steady-state value to the initial value.

[0037] By adopting the above technical solution, the polarity indication of transient leakage current can be quantified by using the leakage current rise slope or the ratio of transient steady-state value to initial value as the criterion.

[0038] Optionally, redundant decision-making is performed on the three results of impedance characteristics, harmonic characteristics and transient leakage current characteristics. In response to conflicts among the three results, it is determined that there is a decision ambiguity.

[0039] By adopting the above technical solution, redundant decision-making is made on the three-way results of impedance, harmonics and transients, so that when a single-way evidence fails, the other two-way results still support the judgment.

[0040] Optionally, relative evidence consisting of the differential residual of the gold plate and outliers of similar components is preferred. In response to the failure of relative evidence, the judgment is switched to absolute polarity indication.

[0041] By adopting the above technical solution, relative evidence is given priority and absolute indication is switched when it becomes invalid, so that the criterion remains available under different board conditions.

[0042] Optionally, the power-on gating has three states: in response to an ambiguous decision, the circuit board is prohibited from powering on and a retest is triggered; in response to reverse polarity, the circuit board is prohibited from powering on and marked; and in response to normal power-on, the circuit board is allowed to power on.

[0043] By adopting the above technical solution, the power-on gate is divided into three states: ambiguous retest, reverse connection marking, and normal release, so that uncertain material positions are not directly released for power-on.

[0044] Optionally, the device under test includes at least one of diodes, transistors, electrolytic capacitors, tantalum capacitors, light-emitting diodes, varistors, or bridge rectifiers.

[0045] By adopting the above technical solution, the components under test are enumerated into various polarity and non-polarity components, so that the test covers common assembly objects.

[0046] Optionally, for non-polar components under test, only S1, S2 and missing component determination are performed, and the polarity orientation determination in S3 is skipped.

[0047] By adopting the above technical solution, polarity determination is skipped for non-polar components, allowing the testing process to be adaptively tailored according to the component attributes.

[0048] Optionally, for the test component that exhibits linear properties and is consistent with the properties of the linear components to be installed, the amplitude-frequency characteristics and phase-frequency characteristics of the electrical response are extracted to form a frequency response fingerprint. The frequency response fingerprint is assigned to a cluster composed of valid part numbers. If the frequency response fingerprint falls outside the cluster, it indicates that although the properties are consistent, the part number is deviated, and the part position status is determined to be incorrectly installed.

[0049] By adopting the above technical solution, the amplitude frequency and phase frequency response fingerprints are used to classify the legitimate part number clusters, so that the misassembly of linear parts falling within the legitimate value range can be identified.

[0050] Optionally, for linear components with consistent properties, misassembly is determined based on the divergence of the component under test from the valid part number cluster at multiple frequencies. In response to a single frequency approaching the cluster while multiple frequencies diverge, the part position status is determined to be misassembly.

[0051] By adopting the above technical solution, misassembly can be determined by multi-frequency divergence, thus separating substitute materials with similar single frequencies but divergent multi-frequency frequencies.

[0052] Optionally, an excitation signal is injected into a single node of the circuit board and the electrical response is acquired at multiple nodes. The component under test is located and its type is determined based on the transfer function pattern of the electrical response as the topological position changes.

[0053] By adopting the above technical solution, single-point injection of multi-node response positioning components enables topological type determination even when there is no complete needle bed contact.

[0054] Secondly, this application provides a circuit board component misassembly and polarity reverse connection detection device based on electrical performance parameters, which adopts the following technical solution: A circuit board component misassembly and polarity reverse connection detection device based on electrical performance parameters, comprising: The excitation acquisition unit is configured to apply an excitation signal to the material level of the component under test on the circuit board, acquire the electrical response of the material level to the excitation signal, and extract the harmonic components generated by the nonlinear transmission characteristics of the component under test from the electrical response. The harmonic components include even harmonic components. The attribute determination unit is configured to determine whether the component under test has linear or nonlinear attributes based on the presence or absence of harmonic components, and compare the linear or nonlinear attributes with the expected attributes of the components to be installed at the material level to obtain the attribute comparison result. The polarity determination unit is configured to compare the phase of the even harmonic component with a reference phase, which is the phase of the even harmonic component of the component to be installed under the correct polarity orientation. The polarity orientation of the component under test is determined based on whether the phase of the even harmonic component is reversed relative to the reference phase. The status determination unit is configured to determine the status of the component under test as normal, incorrectly assembled, reversed polarity, or missing based on the electrical response, attribute comparison results, and polarity orientation. Specifically, if the electrical response is lower than the expected response threshold of the component level, the status is determined to be missing. If the electrical response is not lower than the expected response threshold, further determination is made based on the attribute comparison results and polarity orientation: if the attribute comparison results indicate inconsistent attributes, the status is determined to be incorrectly assembled; if the attribute comparison results indicate consistent attributes and reversed polarity, the status is determined to be reversed polarity; and if the attribute comparison results indicate consistent attributes and positive polarity, the status is determined to be normal.

[0055] By adopting the above technical solution, the excitation acquisition unit, attribute determination unit, polarity determination unit and state determination unit respectively undertake the excitation acquisition, attribute comparison, polarity determination and state determination, so that the above method can obtain the corresponding functional division and parallel execution on the hardware.

[0056] Optionally, the polarity determination unit is further configured to: determine the reference phase based on the even harmonic component of the corresponding material position of the good sample or gold plate of the component to be installed in the correct polarity orientation; determine the polarity orientation as reversed in response to the phase reversal of the even harmonic component of the component under test relative to the reference phase; and use the phase of the odd harmonic component in the electrical response remaining unchanged relative to the phase of the odd harmonic component of the corresponding component as a cross-verification that the polarity orientation is reversed.

[0057] By adopting the above technical solution, the polarity determination unit uses the odd phase invariance as the cross-verification for even phase reversal, so that the polarity determination has self-verification capability at the unit level.

[0058] Optionally, the excitation acquisition unit, attribute determination unit, polarity determination unit, and status determination unit operate in a passive phase before the circuit board is powered on, and the amplitude of the excitation signal is lower than the threshold that would damage the device under test with reverse polarity. The device also includes a power-on gating unit, which is configured to prohibit the circuit board from being powered on in response to the material level status being determined to be reverse polarity, and to allow the circuit board to be powered on normally in response to the material level status being determined to be normal.

[0059] By adopting the above technical solution, each unit operates passively before power-on and is prohibited or allowed by the power-on gate unit, so that the power-on gate is placed before the power-on circuit board in hardware.

[0060] Optionally, the device also includes a transient leakage current detection unit, which is configured to apply a DC bias to the device under test (DUT) which is a nonlinear electrolytic capacitor or tantalum capacitor and collect the transient leakage current characteristics of the DUT, using the evolution of the transient leakage current characteristics over time as an absolute polarity indication; the state determination unit is further configured to determine the material level state after cross-checking the absolute polarity indication with the polarity orientation.

[0061] By adopting the above technical solution, the transient leakage current detection unit provides an absolute polarity indication and works in conjunction with the state determination unit, so that the polarity determination obtains an independent absolute criterion.

[0062] In summary, this application includes at least one of the following beneficial technical effects: 1. By applying an excitation signal to the material level and extracting the harmonic components generated by the nonlinear transmission characteristics of the components, the presence or absence of harmonics, the phase of even harmonics and the amplitude of the electrical response are combined, so that the material level status can be distinguished into four categories from the in-circuit electrical response before the circuit board is powered on: normal, incorrectly installed, reversed polarity and missing. This overcomes the problem that the two-state judgment of a single electrical parameter cannot identify the defect type.

[0063] 2. By using the unchanged phase of odd harmonics as a cross-verification for the reversal of even phases, and introducing an absolute polarity indication of the transient leakage current evolution over time for electrolytic capacitors and tantalum capacitors, the determination of polarity orientation can still be mutually verified in the case of parallel bypass network and batch reverse connection. At the same time, the passive pre-gating control prohibits power-on when the polarity is determined to be reverse connection, so as to avoid damage to polarity-sensitive components due to reverse connection power-on.

[0064] 3. By using the differential residual of the same type of components as a relative benchmark and switching to absolute polarity indication when relative evidence fails, and extracting amplitude and phase frequency response fingerprints of linear components to belong to the legal part number cluster, misassembly within the legal value range of the replacement part width and batch reverse connection without outlier reference can be identified, thus expanding the detection coverage of different component types and assembly deviations. Attached Figure Description

[0065] Figure 1 This is a schematic diagram of the overall process of the circuit board component misassembly and polarity reverse connection detection method based on electrical performance parameters in the embodiments of this application.

[0066] Figure 2 This is a schematic diagram of the sub-process of polarity orientation discrimination cross-validation in the embodiments of this application.

[0067] Figure 3 This is a schematic diagram of the process for material level status determination and consistency adjudication in the embodiments of this application.

[0068] Figure 4 This is a schematic diagram of the passive pre-power-on gate in the embodiments of this application.

[0069] Figure 5 This is a schematic diagram of the circuit board component misassembly and polarity reverse connection detection device based on electrical performance parameters in an embodiment of this application.

[0070] Explanation of reference numerals in the attached figures: 110. Excitation Acquisition Unit; 120. Attribute Determination Unit; 130. Polarity Determination Unit; 140. State Determination Unit; 150. Power-on Gating Unit; 160. Transient Leakage Detection Unit. Detailed Implementation

[0071] 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 a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0072] This application discloses a method and apparatus for detecting mis-assembly and reverse polarity of circuit board components based on electrical performance parameters.

[0073] This method applies an excitation signal to the location of the component under test (DUT) and extracts harmonic components generated by the nonlinear transmission characteristics of the component from the electrical response of the DUT. Using harmonic properties and even-order harmonic phase as two relatively independent observations, the assembly state of the DUT is determined before the circuit board is powered on. First, an excitation signal is applied to the DUT and the electrical response is collected, extracting harmonic components, including even-order harmonics. Then, the presence or absence of harmonic components determines whether the DUT exhibits linear or nonlinear properties and is compared with the components to be installed. The polarity orientation is determined based on whether the even-order harmonics are reversed relative to the reference phase. Finally, by combining the electrical response, property comparison results, and polarity orientation, the DUT state is determined as normal, incorrectly installed, reversed polarity, or missing. Thus, four assembly states can be distinguished from the in-circuit electrical response before the circuit board is powered on.

[0074] Before detailing the embodiments of this application, several technical terms involved in the embodiments will be explained first.

[0075] A component position refers to a location on a circuit board used to assemble a single component. Each component position corresponds to a specific component according to the circuit board's design intent, and the component to be assembled has a defined type, parameters, and polarity orientation. Applying an excitation signal to a component position injects an excitation into that position, and the component position's electrical response to the excitation signal reflects the electrical behavior of the component at that position under excitation.

[0076] Harmonic components refer to the components whose frequencies are integer multiples of the fundamental frequency of the excitation, obtained from the electrical response of the material level through frequency domain decomposition. Components with frequencies even multiples of the fundamental frequency are called even-order harmonic components, and components with frequencies odd multiples of the fundamental frequency are called odd-order harmonic components. Harmonic components are generated by the nonlinearity of the transmission characteristics of components; components with approximately linear transmission characteristics generate almost no harmonic components under excitation.

[0077] The attribute comparison result refers to the result obtained by comparing the linear or nonlinear attribute of the component under test based on whether it has a definite linear attribute or nonlinear attribute based on the harmonic component with the expected attribute of the component to be installed at the material position. It is used to characterize whether the component under test and the component to be installed are consistent in linear or nonlinear attributes.

[0078] Reference phase and polarity orientation: The reference phase refers to the phase of the even-order harmonic component when the component to be installed is in the correct polarity orientation. Polarity orientation refers to whether the polarity direction of the component under test is positive or negative relative to the correct polarity direction of the component to be installed. Whether the phase of the even-order harmonic component is reversed relative to the reference phase can reflect the polarity orientation of the component under test.

[0079] The component status refers to the result obtained after judging the assembly status of the component under test, including four categories: normal, incorrect assembly, reverse polarity, and missing component. Normal indicates that the component under test and the component to be installed have the same properties and the correct polarity orientation, and the part number and parameters are not judged to deviate from the correct component. Incorrect assembly indicates that the component under test and the component to be installed do not match, including inconsistencies in linear or nonlinear properties, or that the components under test and the component to be installed have the same properties but the part number or parameters deviate from the correct component. Reverse polarity indicates that the components under test and the component to be installed have the same properties but the polarity orientation is reversed. Missing component indicates that a component is missing from the component location.

[0080] Decision ambiguity refers to an intermediate state where a conflict arises between the attribute comparison results and polarity orientation when making a consistency decision. Decision ambiguity is an independent intermediate marker in the detection process, used to trigger constraints or retesting, and is not used as a value for the material level status.

[0081] To facilitate understanding, the following example uses two slots on a circuit board to illustrate this method. The first slot should contain an electrolytic capacitor, serving as a polarity-sensitive nonlinear component; the second slot should contain a resistor, serving as a non-polarity linear component. Subsequent examples in the embodiments will follow this scenario.

[0082] The following section provides a detailed explanation of this method, covering aspects such as material level excitation and harmonic extraction, attribute discrimination and mis-installation identification, polarity orientation determination, discrimination of four types of material level states, passive pre-gating, and device mapping. (Refer to...) Figure 1 This method includes steps S1 to S4.

[0083] In step S1, an excitation signal is applied to the material level of the component under test (DUT) on the circuit board. The electrical response of the material level to the excitation signal is collected, and harmonic components generated by the nonlinear transmission characteristics of the DUT are extracted from the electrical response. These harmonic components include even-order harmonic components. In practical implementation, components with approximately linear transmission characteristics generate almost no harmonic components under excitation. Components containing nonlinear units such as PN junctions or magnetic cores generate harmonic components under excitation. The presence or absence of harmonic components reflects whether the DUT has nonlinear transmission characteristics. Harmonic components are generated by the nonlinear transmission characteristics of the DUT itself. Linear components connected in parallel in the same network do not introduce components at harmonic frequencies. Using harmonic components as an observation can avoid the bypassing effect of the parallel network on the detection of the DUT.

[0084] S1 includes sub-steps S11 to S13.

[0085] S11. Apply an excitation signal to the material level, using the excitation signal as the excitation source for that material level, causing the device under test (DUT) at the material level to generate an electrical response under excitation, providing excitation for subsequent acquisition of the electrical response. For example, the frequency band and amplitude of the excitation signal can be selected according to the type of DUT.

[0086] S12. Collect the electrical response of the material level to the excitation signal. The electrical response reflects the electrical transmission behavior of the device under test under excitation and serves as the input for subsequent frequency domain decomposition.

[0087] S13. Perform frequency domain decomposition on the electrical response to separate the fundamental component and each harmonic component, and extract the even harmonic components from the separation results. The extracted harmonic components are used for subsequent determination of attributes and polarity orientation. For example, perform a fast Fourier transform or a sliding discrete Fourier transform on the acquired time-domain electrical response, and read the amplitude and phase of each harmonic component in the spectrum at integer multiples of the excitation fundamental frequency.

[0088] In S1, the form of the excitation signal and the method of acquiring the electrical response can be implemented in various ways.

[0089] In some embodiments, the excitation signal includes a frequency sweep signal applied at multiple frequencies, and the material level status is jointly determined based on the electrical responses of the device under test (DUT) at multiple frequencies. In a specific implementation, the material level is excited point-by-point or continuously within a frequency range, and the electrical responses at each frequency are collected, with corresponding harmonic components and phases extracted. When the differences in properties or polarities are not significant at a single frequency, the electrical responses at multiple frequencies can provide complementary criteria for discrimination from a frequency perspective. For example, the frequency range of the frequency sweep can cover frequency bands where the DUT exhibits significant resonance or nonlinear characteristics.

[0090] The excitation signal can also be one of a bipolar pulse, a stepped wave, or a two-tone signal, simultaneously acquiring harmonic components and polarity information through a single excitation's electrical response. By simultaneously carrying harmonic information for attribute determination and phase information for polarity determination in a single shaping excitation, the detection cycle for a single material level can be shortened. For example, the waveform parameters of the shaping excitation can be set according to the response characteristics of the component under test.

[0091] In other embodiments, the excitation signal is a two-tone signal consisting of two single tones with a non-integer multiple frequency relationship, and even-order harmonic components are extracted from the intermodulation components of the electrical response. In specific implementations, the frequencies of the two single tones are chosen to be non-integer multiples, ensuring that the intermodulation components generated by the two tones under nonlinear transmission in the device under test fall at frequencies separate from the fundamental excitation frequency, thereby preventing the even-order harmonic components from being overwhelmed by the fundamental excitation frequency. For example, even-order harmonic components are read from frequencies selected according to even-order relationships among the intermodulation components such as the sum and difference frequencies of the two single tones.

[0092] In one embodiment, an excitation signal is injected into a single node of the circuit board, and the electrical response is acquired at multiple nodes. The component under test (DUT) is located and its type is determined based on the transfer function pattern of the electrical response as it changes with the topological position. The injected excitation signal propagates along the circuit network, exhibiting different transfer functions at different nodes due to variations in network topology and the transmission characteristics of each component. The change in the electrical response of each node with topological position forms the basis for location and type determination. In situations where it is not possible to contact each component individually with a probe, this method locates and determines the type of the DUT based on its topological position.

[0093] In step S2, the presence or absence of harmonic components determines whether the component under test (DUT) exhibits linear or nonlinear properties. These properties are then compared to the expected properties of the components to be installed at the designated location, yielding a property comparison result. Following the harmonic components extracted in S1, this step maps the presence or absence of these harmonic components to the linear or nonlinear properties of the DUT, and then compares this with the expected properties of the components to be installed at that location, determined according to the design intent. Inconsistent property comparison results indicate that the components installed at the location deviate from the expected linear or nonlinear properties, suggesting a misinstallation at that location.

[0094] S2 includes sub-steps S21 to S22.

[0095] S21. Determine whether the device under test (DUT) exhibits linear or nonlinear properties based on the presence or absence of harmonic components. Using the harmonic components extracted in S1 as input, the DUT is determined to have linear properties when the harmonic components are below a discrimination threshold, and to have nonlinear properties when the harmonic components reach the discrimination threshold. The determined properties are then compared with the expected properties. For example, whether the energy ratio of the harmonic components relative to the fundamental excitation component reaches a discrimination threshold can be used as a criterion.

[0096] S22. Compare the linear or nonlinear attributes with the expected attributes of the components to be installed at the material location to obtain the attribute comparison results. The expected attributes of the components to be installed are determined based on the design intent of the material location, such as from the bill of materials or material location design of the circuit board. When the measured attributes of the component under test are consistent with the expected attributes, the attribute comparison results indicate that the attributes are consistent; when they are inconsistent, they indicate that the attributes are inconsistent. The attribute comparison results are used by S4 to determine the material location status.

[0097] For example, if the first slot should contain an electrolytic capacitor, and the collected electrical response contains harmonic components that reach the discrimination threshold, then the device under test (DUT) at the first slot is determined to have non-linear properties, consistent with the expected non-linear properties of an electrolytic capacitor. If the second slot should contain a resistor, and the harmonic components in the electrical response are below the discrimination threshold, then the DUT is determined to have linear properties, consistent with the expected linear properties of a resistor. However, if the second slot is mistakenly fitted with a diode, then the electrical response will contain harmonic components that reach the discrimination threshold, indicating a non-linear property, inconsistent with the expected linear properties of a resistor, and the property comparison results will show inconsistent properties.

[0098] In other embodiments, the attribute is determined by whether the signal-to-noise ratio of the harmonic component relative to the excitation fundamental component exceeds a set threshold, or the attribute determination result is verified by the consistency of the harmonic components at multiple frequencies, so as to adapt to the attribute determination under different components and different signal conditions.

[0099] Based on determining the properties of the component under test (DUT), its type can be further distinguished. Specifically, the relative magnitudes of the second and third harmonic components in the electrical response can differentiate the DUT into linear components, components containing PN junctions, or components containing magnetic cores. Components containing PN junctions exhibit unidirectional asymmetric transmission characteristics with forward conduction and reverse cutoff, and under excitation, even-order harmonic components dominate. Components containing magnetic cores exhibit odd-symmetric characteristics of hysteresis loops, and under excitation, odd-order harmonic components dominate. Linear components have very weak second and third harmonic components. The relative magnitudes of the second and third harmonic components can distinguish these three types of components.

[0100] The components under test can include at least one of diodes, transistors, electrolytic capacitors, tantalum capacitors, light-emitting diodes (LEDs), varistors, or bridge rectifiers. Among these, the polarity orientation of polarized components such as electrolytic capacitors, tantalum capacitors, diodes, and LEDs needs to be determined; the polarity orientation of non-polarized components such as resistors and varistors is not involved. The differences in harmonic components and polarity characteristics of the aforementioned components constitute the physical basis for this method to determine their attributes and polarity.

[0101] For non-polar components under test (DUTs), only steps S1, S2, and the missing component determination are performed, skipping step S3 for polarity orientation determination. Since non-polar components lack polarity, determining their polarity orientation is meaningless. Therefore, after identifying the DUT as a non-polar component such as a resistor or varistor, only S1 is used to acquire the electrical response and extract harmonic components, and S2 is used to determine and compare attributes. Then, whether the electrical response is below the expected response threshold is used to determine if a missing component is present, without proceeding to step S3 for polarity orientation determination. For example, for a resistor in the second position, after determining its non-polar linear attribute, its position status is determined solely based on the attribute comparison results and the missing component determination. The testing process is adaptively tailored to the attributes of the DUT.

[0102] For components under test (DUTs) exhibiting linear properties, i.e., properties consistent with those of the linear components to be installed, it is difficult to distinguish different part numbers belonging to the same linear category based solely on harmonic properties, as they generate almost no harmonic components under excitation. In some embodiments, for such linear components consistent with the properties of the components to be installed, the amplitude-frequency and phase-frequency characteristics of the electrical response are further extracted to form a frequency response fingerprint. The frequency response fingerprint is assigned to a cluster composed of valid part numbers. If the frequency response fingerprint falls outside the cluster, it indicates that although the DUT has the same properties as the components to be installed, its part number deviates, and the part number status is determined to be incorrectly installed. In a specific implementation, the electrical response of the part number is collected at multiple frequencies to obtain the amplitude-frequency characteristic (amplitude varies with frequency) and the phase-frequency characteristic (phase varies with frequency), which together constitute the frequency response fingerprint of the part number. A valid part number cluster is pre-established based on the frequency response characteristics of each valid part number. The frequency response fingerprint of the DUT is compared with the valid part number cluster. If the frequency response fingerprint falls within the cluster, it indicates that the DUT belongs to a valid part number; if it falls outside the cluster, it indicates that the DUT deviates from all valid part numbers, and the part number status is determined to be incorrectly installed. For example, if a resistor of a certain value is to be installed in the second part number, and it is incorrectly installed with a different value or package, its amplitude and phase frequency characteristics will deviate from the valid part number cluster, and the frequency response fingerprint will fall outside the cluster, which will be judged as incorrect installation.

[0103] For linear components with consistent properties, misassembly can be determined based on the divergence of the component under test (DUT) from the valid part number cluster at multiple frequencies. This is indicated by a single frequency close to the cluster while multiple frequencies diverge, classifying the component as misassembled. In practice, the frequency response fingerprint of the DUT is calculated at multiple frequencies relative to the valid part number cluster, and the divergence of this deviation at multiple frequencies is used as the criterion. Substitute components may be close to the valid part number cluster at individual frequencies, but their deviations at multiple frequencies are more dispersed, exhibiting greater divergence. Therefore, DUTs that are close at a single frequency but diverge at multiple frequencies are classified as misassembled. This allows for the separation of substitute components that fall within the valid range at individual frequencies but deviate from the valid part number cluster in the overall frequency response.

[0104] Reference Figure 2 In step S3, the phase of the even-order harmonic component is compared with the reference phase, which is the phase of the even-order harmonic component when the component is correctly oriented. The polarity orientation of the component is determined based on whether the phase of the even-order harmonic component is reversed relative to the reference phase. Following the even-order harmonic component extracted in S1 and the nonlinear properties determined in S2, this step determines the polarity orientation of the component under test that exhibits nonlinear properties and polarity.

[0105] The phase of even-order harmonic components is determined by the nonlinear transmission characteristics of the component under test (DUT). Polarized components have asymmetrical current-voltage characteristics in their forward and reverse directions. The polarity of the component determines the direction of this asymmetrical transmission characteristic, which in turn determines the phase of the even-order harmonic components. When the DUT is connected with the correct polarity reversed relative to the corresponding component, its current-voltage characteristics are reversed, and the phase of the even-order harmonic components is approximately 180° reversed relative to the reference phase. This determination is performed in the passive stage before the circuit board is powered on, and the even-order harmonic components are generated by the nonlinear transmission characteristics of the DUT itself.

[0106] S3 includes sub-steps S31 to S32.

[0107] S31. Extract the phase of the even-order harmonic component and compare it with the reference phase. Using the even-order harmonic component extracted in S1 as input, read its phase, subtract the reference phase from the phase to obtain the phase difference, and use the phase difference to determine the polarity orientation in S32. For example, read the phase of the even-order harmonic component at the even-harmonic point of the excitation fundamental frequency and compare it with the reference phase.

[0108] S32. Determine the polarity orientation of the component under test based on whether the phase of the even-order harmonic component is reversed relative to the reference phase. A phase difference close to zero indicates a positive polarity orientation, while a phase difference close to 180° (phase reversal) indicates a negative polarity orientation. This determined polarity orientation is used in S4 to determine the material level status. For example, for an electrolytic capacitor at the first material level, if the phase of its even-order harmonic component is reversed relative to the reference phase, the polarity orientation is determined to be negative, indicating that the material level may be connected with reversed polarity.

[0109] In some embodiments, the reference phase in S3 is determined by the even-order harmonic components of a good sample of the component to be installed in the correct polarity orientation or the corresponding position on a gold plate. In response to the phase reversal of the even-order harmonic components of the component under test relative to the reference phase, the polarity orientation is determined to be reversed. Simultaneously with the phase reversal of the even-order harmonic components relative to the reference phase, the phase of the odd-order harmonic components in the electrical response remains unchanged relative to the phase of the odd-order harmonic components of the corresponding component, serving as a cross-verification for reverse polarity orientation. The reference phase is taken from a good sample of the component to be installed in the correct polarity orientation, or from the even-order harmonic components of the corresponding position on a gold plate with the same circuit board layout, serving as the phase reference for polarity determination of the component under test. The phase of the odd-order harmonic components is mainly determined by the odd-symmetric part of the component's transmission characteristics and is not sensitive to the component's polarity direction. When the polarity of the component under test is reversed, the phase of its odd-order harmonic components remains essentially unchanged relative to the phase of the odd-order harmonic components of the corresponding component. Using the simultaneous validity of the phase reversal of even harmonic components and the phase invariance of odd harmonic components as a cross-verification with reverse polarity orientation, can provide independent evidence for reverse discrimination when the phase of even harmonic components is susceptible to interference from parallel networks or noise.

[0110] Even-order harmonic components can be represented by the second harmonic component. The polarity orientation is determined to be reversed by the phase reversal of the second harmonic component relative to the reference phase. The second harmonic component has the lowest order among even-order harmonic components, higher energy relative to the excitation fundamental component, and a higher signal-to-noise ratio. Using the phase of the second harmonic component as the basis for polarity determination makes the determination of phase reversal relatively clear.

[0111] For nonlinear components such as electrolytic capacitors or tantalum capacitors, a DC bias is applied to the component, and transient leakage current characteristics are collected. The evolution of the transient leakage current characteristics over time is used as an absolute polarity indicator. The absolute polarity indicator is cross-checked with the polarity orientation to determine the component level status. The leakage current of electrolytic capacitors and tantalum capacitors evolves differently over time under forward and reverse bias. Under forward bias, the leakage current decays quickly to a lower level due to the self-healing of the oxide film, while under reverse bias, the leakage current decays slowly or increases over time. The evolution of the transient leakage current characteristics over time is used as an absolute polarity indicator, which is independent of the reference phase of the component and can independently provide the polarity direction. The absolute polarity indicator is cross-checked with the polarity orientation obtained in step S3. If they match, the polarity determination result is confirmed; if they do not match, a check of the component level is prompted. For example, a DC bias is applied to the electrolytic capacitor in the first component level, and the evolution of its leakage current over time is observed. The observation window is in the range of milliseconds to seconds.

[0112] The criteria for determining transient leakage current characteristics can be either the slope of the leakage current increase over time or the ratio of the transient steady-state value to the initial value. When using the slope of the leakage current increase over time as the criterion, the slope of the leakage current increase over time under reverse bias is greater than that under forward bias, thus distinguishing the bias direction and indicating polarity. When using the ratio of the transient steady-state value to the initial value as the criterion, this ratio under reverse bias is different from that under forward bias, thus indicating polarity. Both criteria quantify the evolution of transient leakage current over time into comparable values.

[0113] In step S4, the component level status of the device under test (DUT) is determined based on the electrical response, attribute comparison results, and polarity orientation. The DUT status can be one of the following: normal, incorrect assembly, reverse polarity, or missing component. Following the electrical response from S1, the attribute comparison results from S2, and the polarity orientation from S3, this step integrates these three factors and categorizes the DUT status into one of four types using a cascaded discrimination method. The characteristics of the three types of defects on a single electrical parameter may overlap. This step utilizes two relatively independent observations: harmonic attributes and even-order phase. First, missing components are separated by whether the electrical response is below the expected response threshold; then, incorrect assembly is separated by whether the attributes are consistent; finally, reverse polarity is used to distinguish between reverse polarity and normal assembly, thus progressively identifying the four assembly states. The phase discrimination of even-order harmonic components is based on the premise that the DUT exhibits nonlinear properties; non-polar linear components are not involved in polarity orientation discrimination.

[0114] Reference Figure 3 S4 includes sub-steps S41 to S43.

[0115] S41. In response to an electrical response lower than the expected response threshold for the material level, the material level status is determined to be missing. Using the electrical response from S1 as input, the electrical response is compared with the expected response threshold for that material level. If the electrical response is lower than the expected response threshold, it indicates that a component is missing from the material level, and the material level status is determined to be missing. If the electrical response is not lower than the expected response threshold, proceed to S42. For example, the expected response threshold is set based on the nominal response of the component that should be installed at the material level.

[0116] S42. Responding to an electrical response not lower than the expected response threshold, determine misassembly based on attribute comparison results. Using the attribute comparison results from S2 as input, if the attribute comparison results indicate inconsistent attributes, the material position status is determined to be misassembly; if the attribute comparison results indicate consistent attributes, proceed to S43. Attribute inconsistency indicates that the linear or nonlinear attributes of the components at the material position deviate from the required components, pointing to misassembly. The determination of misassembly includes two complementary paths: one is the determination based on the attribute comparison results indicating inconsistent attributes in this step; the other is to determine whether the part number deviates for linear components with consistent attributes using the aforementioned frequency response fingerprint or multi-frequency dispersion. If the part number deviates, it is corrected to misassembly before S43 determines it is normal.

[0117] S43. For components under test with consistent attributes, distinguish between reverse polarity and normal polarity based on polarity orientation. Using the polarity orientation in S3 as input, if the attribute comparison result indicates that the attributes are consistent and the polarity orientation is reversed, the material level status is determined to be reverse polarity; if the attribute comparison result indicates that the attributes are consistent and the polarity orientation is positive, the material level status is determined to be normal.

[0118] For example, the first material level should be equipped with an electrolytic capacitor, whose electrical response is not lower than the expected response threshold and whose attribute comparison results are consistent. If the phase of the even-order harmonic component is reversed relative to the reference phase and the polarity orientation is reversed, then the material level status of the first material level is determined to be reverse polarity; if the polarity orientation is positive, then it is determined to be normal. The second material level should be equipped with a resistor, whose electrical response is not lower than the expected response threshold. If the attribute comparison results are consistent and it is a non-polar component, then it is processed normally; if it is mistakenly installed as a diode and the attribute comparison results are inconsistent, then it is determined to be incorrectly installed; if the electrical response is lower than the expected response threshold, then it is determined to be missing.

[0119] In S4, consistency determination can also be made between the attribute comparison results and polarity orientation. If the attribute comparison results conflict with the polarity orientation, a determination ambiguity is identified. In response to this ambiguity, the level status of other material positions on the circuit board within the same network as the component under test is used to constrain the level status of the component under test, or the amplitude of the excitation signal is increased before re-executing S1 to S4 to eliminate the ambiguity. After the ambiguity is eliminated, the level status is determined according to S4. The attribute comparison results and polarity orientation are obtained from two observations: harmonic attributes and even-order phase, which usually corroborate each other. When the attribute comparison results conflict with the polarity orientation, a determination ambiguity is identified. For example, the phase indication polarity of even-order harmonic components may be reversed, while the absolute polarity indication of transient leakage current characteristics points forward, creating a conflict between the two polarity indicators. Another example is a component under test exhibiting non-linear properties after attribute comparison, which should provide a clear even-order harmonic phase reading. However, if the phase of the even-order harmonic component is between forward and reverse, its polarity cannot be determined, and the attribute indication and polarity evidence cannot corroborate each other. All of these situations indicate a decision ambiguity. Decision ambiguity is an independent intermediate marker in the detection process and is not used as a value for the material level status, which remains limited to four categories: normal, incorrect installation, reverse polarity connection, and missing installation. When decision ambiguity exists, one approach is to constrain the current material level by applying constraints based on the determined material level status of other material levels in the same network. For example, if adjacent material levels in the same network have been determined to be normal, the possible states of the current material level are constrained. Another approach is to increase the amplitude of the excitation signal and re-execute S1 to S4 to improve the signal-to-noise ratio of the harmonic components and phase. After the decision ambiguity is eliminated, the material level status is determined according to S4.

[0120] Before performing conformity determination, the electrical response of the component under test (DUT) can be differentially analyzed with the corresponding electrical response on the gold plate to obtain a differential residual. The gold plate and the circuit board have identical layouts. The differential residual of a reference component on the circuit board of the same type as the DUT is used as a relative benchmark. DUTs that deviate from this benchmark are considered candidates for misassembly or reverse polarity and participate in conformity determination. The gold plate is a correctly assembled circuit board with the same layout as the DUT. The differential residual is obtained by subtracting the electrical response of the DUT from the corresponding electrical response on the gold plate. This residual represents the deviation of the DUT from its correct assembly. Circuit boards often contain multiple components of the same type. Using the differential residuals of these reference components as a relative benchmark can offset the shared process and environmental influences of these components. When the differential residual of the DUT deviates from this benchmark, it is considered a candidate for misassembly or reverse polarity, and this candidate then participates in conformity determination. For example, the differential residual of the electrolytic capacitor at the first material position is compared with that of other electrolytic capacitors of the same type on the circuit board, and the material position that deviates from the relative reference is selected as a candidate for adjudication.

[0121] Differential residuals can be categorized into harmonic residuals and impedance residuals. For nonlinear devices under test (DUTs), harmonic residuals are used, while for linear DUTs, impedance residuals are used. For nonlinear DUTs, the difference is primarily reflected in harmonic components; the difference between the measured material level and the corresponding material level on the gold plate in each harmonic component is taken as the harmonic residual. For linear DUTs, the difference is primarily reflected in impedance characteristics; the difference between the measured material level and the corresponding material level on the gold plate in impedance characteristics is taken as the impedance residual. Matching the type of differential residual to the properties of the DUT ensures that both nonlinear and linear components can obtain differential criteria appropriate to their characterization.

[0122] The reference components can be multiple diodes in a bridge rectifier, multiple capacitors in a parallel bypass, or two transistors in a differential pair. A bridge rectifier consists of four diodes connected in a fixed topology; these four diodes are of the same type and can serve as reference components for each other. Similarly, multiple capacitors in a parallel bypass are of the same type and can serve as reference components for each other. The two transistors in a differential pair are symmetrically arranged and of the same type, and can serve as reference components for each other. By using these already grouped, similar components as references, self-reference can be implemented in various packages and circuit configurations, including bridge rectifiers, parallel capacitors, and differential pairs.

[0123] For multiple identical components under test (DUTs) located in the same local circuit, the harmonic components of each DUT are directly compared, and DUTs deviating from the group are considered candidates, eliminating the need for a differential plate. Multiple identical components are often configured within the same local circuit. Harmonic components are extracted from each of these components and grouped statistically. Normally assembled identical components have relatively similar harmonic components, forming a group. When the harmonic component of a DUT deviates from this group, it is considered a candidate for anomaly. This comparison is performed within the same local circuit, using identical components within the group as benchmarks. Even without a differential plate, components deviating from the group can still be identified. For example, the harmonic components of four diodes in a bridge rectifier are directly compared, and diodes whose harmonic components deviate from the other three are considered candidates.

[0124] As a fallback method, in response to the absence of outliers among similar reference components, the suspected batch of reverse-connected components is switched to a determination based on the absolute polarity indication of the phase of even-order harmonic components or transient leakage characteristics. Relative comparison using similar reference components as a benchmark relies on differences within the group; when multiple components of the same part number are connected in the same reverse direction in a batch, the components themselves are not outliers relative to each other, making it difficult to detect anomalies through relative comparison. Therefore, when no outliers are found among similar reference components, this situation is considered a suspected batch of reverse-connected components, and the determination is switched to an absolute polarity indication based on the reversal of the phase of even-order harmonic components relative to the reference phase, or the evolution of transient leakage characteristics over time. The absolute polarity indication is based on the correct polarity of the component to be installed and does not rely on differences within the group, ensuring that the location of a batch of reverse-connected components can still be identified.

[0125] Redundant adjudication is performed on the three results of impedance characteristics, harmonic characteristics, and transient leakage current characteristics. If the three results conflict, an ambiguity exists in the adjudication. Impedance characteristics reflect the linear impedance of the device under test (DUT), harmonic characteristics reflect its nonlinearity, and transient leakage current characteristics reflect its polarity direction. These three characteristics discriminate the DUT from different dimensions. Redundant adjudication of the three results ensures high reliability of the judgment when all three are consistent, and ambiguity exists when the three results conflict. This redundancy ensures that if one result fails due to noise or local interference, the remaining two results can still support the judgment.

[0126] The relative evidence, consisting of the differential residual of the gold plate and outliers of similar components, is given priority. In response to the invalidation of this relative evidence, the judgment is switched to absolute polarity indication. Both the differential residual of the gold plate and outliers of similar components are relative evidence, based on correct assembly or a group of similar components. In most cases, this evidence has high sensitivity and can be given priority. When the gold plate is unavailable, or when similar components do not exhibit outliers due to batch-wide unidirectional deviation, the relative evidence becomes invalid, and the judgment is switched to absolute polarity indication based on even-order harmonic component phase or transient leakage characteristics. Therefore, the criterion remains usable under different board conditions.

[0127] Reference Figure 4 S1 to S4 can be executed in the passive stage before the circuit board is powered on. The amplitude of the excitation signal is lower than the threshold that would damage the component under test with reverse polarity. In response to the material level status being determined to be reverse polarity, powering on the circuit board is prohibited; in response to the material level status being determined to be normal, powering on the circuit board is allowed. In this method, S1 to S4 apply low-amplitude excitation to the material level and collect the electrical response. The discrimination is completed in the passive stage before the circuit board is powered on. The amplitude of the excitation signal is lower than the threshold that would damage the component under test with reverse polarity. The material level discrimination is performed in this passive stage without subjecting the component to operating voltage. After S4 determines the material level status, powering on the circuit board is gated according to the determination result. When the material level status is determined to be reverse polarity, powering on the circuit board is prohibited, preventing the component with reverse polarity from being subjected to operating voltage; when the material level status is determined to be normal, powering on the circuit board is allowed. For example, if the electrolytic capacitor in the first material position is determined to be reverse polarity, the circuit board should be prevented from being powered on and should be tested again after repair.

[0128] The power-on gating system can also have three states: responding to ambiguity in the decision and prohibiting the circuit board from powering on and triggering a retest; responding to reverse polarity and prohibiting the circuit board from powering on and marking it; and responding to normal status and allowing the circuit board to power on. When there is ambiguity in the decision, the power-on gating system prohibits the circuit board from powering on and triggers a retest for that material level. Processing is only resumed after the ambiguity is resolved and the material level status is determined. When the material level status is determined to be reverse polarity, the power-on gating system prohibits the circuit board from powering on and marks the material level for location and rework. When the material level status is determined to be normal, the power-on gating system allows the circuit board to power on. These three states of the power-on gating system prevent circuit boards with ambiguity in the decision and whose material level status is not yet determined from being directly powered on.

[0129] This application also discloses a circuit board component misassembly and polarity reverse connection detection device based on electrical performance parameters, referring to... Figure 5 The device includes an excitation acquisition unit 110, an attribute determination unit 120, a polarity determination unit 130, and a state determination unit 140, and is used to perform the detection method described above.

[0130] The excitation acquisition unit 110 is configured to apply an excitation signal to the material level where the component under test is located on the circuit board, acquire the electrical response of the material level to the excitation signal, and extract the harmonic components generated by the nonlinear transmission characteristics of the component under test from the electrical response. The harmonic components include even harmonic components, corresponding to S1 above.

[0131] The attribute determination unit 120 is configured to determine whether the component under test has linear or nonlinear attributes based on the presence or absence of harmonic components, and compare the linear or nonlinear attributes with the expected attributes of the components to be installed at the material level to obtain the attribute comparison result, corresponding to S2 above.

[0132] The polarity determination unit 130 is configured to compare the phase of the even harmonic component with a reference phase, which is the phase of the even harmonic component of the component to be installed under the correct polarity orientation. The polarity orientation of the component under test is determined based on whether the phase of the even harmonic component is reversed relative to the reference phase, corresponding to S3 above.

[0133] The status determination unit 140 is configured to determine the status of the component under test as normal, incorrectly installed, reversed polarity, or missing based on the electrical response, attribute comparison results, and polarity orientation, corresponding to S4 above. The specific limitations of each unit when performing the corresponding steps are the same as the limitations of the corresponding steps in the method above, and the similarities will not be repeated.

[0134] In some embodiments, the polarity determination unit 130 is further configured to determine a reference phase based on the even-order harmonic components of the corresponding material position of a good sample or gold plate with the component to be installed in the correct polarity orientation; to determine that the polarity orientation is reversed in response to the phase reversal of the even-order harmonic components of the component under test relative to the reference phase; and to use the fact that the phase of the odd-order harmonic components in the electrical response remains unchanged relative to the phase of the odd-order harmonic components of the corresponding component as a cross-verification for the reverse polarity orientation. This configuration of the polarity determination unit 130 is the same as the reference phase acquisition and odd-order harmonic cross-verification process described in S3 above.

[0135] In some embodiments, the excitation acquisition unit 110, attribute determination unit 120, polarity determination unit 130, and state determination unit 140 operate in a passive phase before the circuit board is powered on, and the amplitude of the excitation signal is lower than the threshold that would damage the component under test with reverse polarity. The device also includes a power-on gating unit 150, which is configured to prohibit the circuit board from being powered on in response to a material level state being determined to be reverse polarity, and to allow the circuit board to be powered on in response to a material level state being determined to be normal. The operation of each unit in the passive phase and the gating of the power-on gating unit 150 are the same as the processes performed in the passive phase of S1 to S4 above, which involve gating power-on based on the material level state.

[0136] In some embodiments, the device further includes a transient leakage current detection unit 160, which is configured to apply a DC bias to a nonlinear electrolytic capacitor or tantalum capacitor under test and collect transient leakage current characteristics of the device under test, using the evolution of the transient leakage current characteristics over time as an absolute polarity indication; the state determination unit 140 is further configured to determine the material level state after cross-checking the absolute polarity indication with the polarity orientation. This configuration of the transient leakage current detection unit 160 and the state determination unit 140 is the same as the above-described process of applying a DC bias to electrolytic capacitors and tantalum capacitors to collect transient leakage current characteristics for absolute polarity indication.

[0137] In terms of hardware implementation, the above-mentioned units can be implemented by dedicated hardware circuits, by a general-purpose processor executing program instructions stored in memory, or by a combination of hardware circuits and program instructions. In one specific implementation, the device includes an excitation signal source, a signal acquisition front end, a processor and a memory, as well as a probe or bed of needles fixture that contacts the circuit board material position; the processor is coupled to the excitation signal source and the signal acquisition front end respectively, and the memory stores a program that can be executed by the processor. When the processor executes the program, it realizes the functions of the excitation acquisition unit 110, the attribute determination unit 120, the polarity determination unit 130 and the state determination unit 140.

[0138] In its specific implementation, the excitation acquisition unit 110 consists of an excitation signal source and a signal acquisition front-end. The excitation signal source uses an arbitrary waveform generator or a direct digital frequency synthesizer. After buffering or power amplification, it applies a sweep frequency signal, bipolar pulse, stepped wave, or two-tone signal to the material level through a probe or needle bed fixture. The signal acquisition front-end includes a preamplifier and anti-aliasing filter signal conditioning circuit, as well as an analog-to-digital converter. It converts the electrical response of the material level into a digital signal and sends it to the processor. The processor performs a fast Fourier transform or a sliding discrete Fourier transform to extract the harmonic components.

[0139] In their specific implementation, the attribute determination unit 120, polarity determination unit 130, and state determination unit 140 are executed by a processor executing a program in memory: the processor performs threshold comparison on the extracted harmonic components to obtain the attribute comparison result, performs phase comparison on the even-order harmonic components to obtain the polarity orientation, and then performs cascaded adjudication on the electrical response, attribute comparison result, and polarity orientation to obtain the material level state. The processor can be one or more of a digital signal processor, field-programmable gate array, microcontroller, or general-purpose central processing unit.

[0140] In its specific implementation, the transient leakage current detection unit 160 includes a programmable DC bias source and a leakage current sampling circuit. The programmable DC bias source applies a DC bias to the device under test, and the leakage current sampling circuit collects the leakage current through transimpedance amplification and analog-to-digital conversion. The processor reads the evolution of the leakage current over time as an absolute polarity indicator.

[0141] In a specific implementation, the power-on gate control unit 150 includes a controlled switch connected in series with the power supply path of the circuit board. The controlled switch can be a relay or a power switching device. The processor outputs a gate control signal according to the material level status to control the on / off state of the controlled switch, so as to prohibit or allow the circuit board to be powered on.

[0142] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments, and the same or similar parts between the various embodiments can be referred to each other.

[0143] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for detecting misplacement and reverse connection of components on a circuit board based on electrical performance parameters, characterized in that, Includes the following steps: S1. Apply an excitation signal to the material level where the component under test is located on the circuit board, collect the electrical response of the material level to the excitation signal, and extract the harmonic components generated by the nonlinear transmission characteristics of the component under test from the electrical response, wherein the harmonic components include even harmonic components. S2. Based on the presence or absence of the harmonic components, determine whether the component under test has linear or nonlinear properties, and compare the linear or nonlinear properties with the expected properties of the components to be installed at the material level to obtain the property comparison result. S3. Compare the phase of the even harmonic component with a reference phase, wherein the reference phase is the phase of the even harmonic component of the component to be installed under the correct polarity orientation. Determine the polarity orientation of the component under test based on whether the phase of the even harmonic component is reversed relative to the reference phase. S4. Based on the electrical response, the attribute comparison result, and the polarity orientation, determine the material level status of the component under test, wherein the material level status is one of normal, incorrect assembly, reverse polarity, or missing assembly; wherein, in response to the electrical response being lower than the expected response threshold of the material level, the material level status is determined to be missing assembly; in response to the electrical response not being lower than the expected response threshold, further determine based on the attribute comparison result and the polarity orientation: if the attribute comparison result indicates inconsistent attributes, determine the material level status to be incorrect assembly; if the attribute comparison result indicates consistent attributes and the polarity orientation is reversed, determine the material level status to be reverse polarity; if the attribute comparison result indicates consistent attributes and the polarity orientation is positive, determine the material level status to be normal.

2. The method for detecting mis-insertion and reverse connection of a circuit board component based on electrical performance parameters according to claim 1, characterized in that, In step S3, the reference phase is determined by the even harmonic component of the corresponding material position of the good sample or gold plate of the component to be installed under the correct polarity orientation; in response to the phase reversal of the even harmonic component of the component under test relative to the reference phase, the polarity orientation is determined to be reversed. While the phase of the even harmonic component is reversed relative to the reference phase, the phase of the odd harmonic component in the electrical response remains unchanged relative to the phase of the odd harmonic component of the component to be installed, as a cross-verification that reverses the polarity orientation.

3. The method for detecting mis-assembly and reverse polarity of circuit board components based on electrical performance parameters according to claim 2, characterized in that, For the device under test (DUT) exhibiting the aforementioned nonlinear properties and being an electrolytic capacitor or a tantalum capacitor, a DC bias is applied to the DUT and the transient leakage current characteristics of the DUT are collected. The evolution of the transient leakage current characteristics over time is used as an absolute polarity indicator. The absolute polarity indicator is cross-checked with the polarity orientation to determine the material level status.

4. The method for detecting mis-assembly and reverse polarity of circuit board components based on electrical performance parameters according to claim 1, characterized in that, S1 to S4 are performed in a passive phase before the circuit board is powered on, and the amplitude of the excitation signal is lower than the threshold that would damage the component under test with reverse polarity. In response to the material level status being determined to be reverse polarity, the circuit board is prohibited from being powered on; in response to the material level status being determined to be normal, the circuit board is allowed to be powered on.

5. The method for detecting mis-assembly and reverse polarity of circuit board components based on electrical performance parameters according to claim 1, characterized in that, In step S4, a consistency determination is made between the attribute comparison result and the polarity orientation. In response to a conflict between the attribute comparison result and the polarity orientation, an ambiguity in the determination is identified. In response to the existence of the decision ambiguity, the level state of the device under test is constrained by the level state of other positions on the circuit board that are in the same network as the device under test, or the amplitude of the excitation signal is increased and S1 to S4 are re-executed to eliminate the decision ambiguity, and the level state is determined according to S4 after the decision ambiguity is eliminated.

6. The method for detecting mis-assembly and reverse polarity of circuit board components based on electrical performance parameters according to claim 5, characterized in that, Before the consistency determination, the electrical response of the material position is differentially compared with the electrical response of the corresponding material position on the gold plate to obtain the differential residual. The gold plate has the same layout as the circuit board. The differential residual of a reference component on the circuit board that is the same type as the component under test is used as a relative benchmark. The component under test that deviates from the relative benchmark is considered as a candidate for the presence of the misassembly or the reverse polarity and participates in the consistency determination.

7. A device for detecting mis-assembly and reverse polarity of circuit board components based on electrical performance parameters, characterized in that, include: An excitation acquisition unit is configured to apply an excitation signal to the material level of the component under test on the circuit board, acquire the electrical response of the material level to the excitation signal, and extract the harmonic components generated by the nonlinear transmission characteristics of the component under test from the electrical response, wherein the harmonic components include even harmonic components. The attribute determination unit is configured to determine whether the component under test has linear or nonlinear attributes based on the presence or absence of the harmonic components, and to compare the linear or nonlinear attributes with the expected attributes of the components to be installed at the material level to obtain an attribute comparison result. A polarity determination unit is configured to compare the phase of the even harmonic component with a reference phase, wherein the reference phase is the phase of the even harmonic component presented by the component under the correct polarity orientation, and to determine the polarity orientation of the component under test based on whether the phase of the even harmonic component is reversed relative to the reference phase. A state determination unit is configured to determine the material level status of the component under test as normal, incorrectly assembled, reversed polarity, or missing based on the electrical response, the attribute comparison result, and the polarity orientation. Specifically, if the electrical response is lower than the expected response threshold for the material level, the material level status is determined to be missing. If the electrical response is not lower than the expected response threshold, further determination is made based on the attribute comparison result and the polarity orientation: if the attribute comparison result indicates inconsistent attributes, the material level status is determined to be incorrectly assembled; if the attribute comparison result indicates consistent attributes and the polarity orientation is reversed, the material level status is determined to be reversed polarity; if the attribute comparison result indicates consistent attributes and the polarity orientation is positive, the material level status is determined to be normal.

8. The circuit board component misassembly and polarity reverse connection detection device based on electrical performance parameters according to claim 7, characterized in that, The polarity determination unit is further configured to: determine the reference phase based on the even harmonic component of the corresponding material position of the good sample or gold plate of the component to be installed under the correct polarity orientation; determine that the polarity orientation is reversed in response to the phase reversal of the even harmonic component of the component under test relative to the reference phase; and use the fact that the phase of the odd harmonic component in the electrical response remains unchanged relative to the phase of the odd harmonic component of the component to be installed as a cross-verification that the polarity orientation is reversed.

9. The circuit board component misassembly and polarity reverse connection detection device based on electrical performance parameters according to claim 7, characterized in that, The excitation acquisition unit, the attribute determination unit, the polarity determination unit, and the state determination unit operate in a passive phase before the circuit board is powered on. The amplitude of the excitation signal is lower than the threshold that would damage the component under test if the polarity is reversed. The device also includes a power-on gating unit, which is configured to prohibit the circuit board from being powered on in response to the material level state being determined to be reversed polarity, and to allow the circuit board to be powered on normally in response to the material level state being determined to be normal.

10. The circuit board component misassembly and polarity reverse connection detection device based on electrical performance parameters according to claim 8, characterized in that, The device further includes a transient leakage current detection unit, which is configured to apply a DC bias to the device under test (DUT) exhibiting the nonlinear properties and being an electrolytic capacitor or a tantalum capacitor, and to collect the transient leakage current characteristics of the DUT, using the evolution of the transient leakage current characteristics over time as an absolute polarity indication; the state determination unit is further configured to determine the material level state after cross-checking the absolute polarity indication with the polarity orientation.

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