CN-121994744-A - Terahertz wave-based nondestructive detection device for substrate defects under copper bar plating layer

CN121994744ACN 121994744 ACN121994744 ACN 121994744ACN-121994744-A

Abstract

The invention relates to the technical field of nondestructive testing, in particular to a terahertz wave-based nondestructive testing device for substrate defects under a copper bar plating layer, which comprises a terahertz scanning acquisition module, a control module and a control module, wherein the terahertz scanning acquisition module is used for controlling a transmitting and receiving unit to perform two-dimensional scanning so as to acquire an original waveform; the invention discloses a method for detecting the thickness of a coating on a substrate, which comprises a flight time dynamic correction module, a substrate roughness deconvolution module, an interface dielectric characteristic analysis module and a defect risk assessment imaging module, wherein the flight time dynamic correction module is used for calculating the thickness of the local coating and aligning a dynamic time axis, the substrate roughness deconvolution module is used for calling a reference model to conduct deconvolution filtering to strip background scattering noise, the interface dielectric characteristic analysis module is used for extracting dielectric characteristic vectors reflecting the abrupt state of the dielectric constant of the interface, and the defect risk assessment imaging module is used for constructing a three-dimensional chromatography map and outputting a detection result.

Inventors

WANG SHIQI
Zheng Bingkang
XIAO LING
LI RUI
KONG QINGSHUANG

Assignees

福建佳鑫金属科技有限公司

Dates

Publication Date: 20260508
Application Date: 20260123

Claims (8)

1. The utility model provides a substrate defect nondestructive test device under copper bar cladding material based on terahertz wave which characterized in that includes: the terahertz scanning acquisition module is used for controlling the terahertz time-domain spectrum transmitting and receiving unit to perform two-dimensional point-by-point scanning on the copper bar surface to be detected, and acquiring the reflected echo signals of all scanning points to obtain an original terahertz time-domain waveform sequence; The time-of-flight dynamic correction module is used for analyzing a first echo peak of an air and coating interface and a second echo peak of a coating and substrate interface in the original terahertz time-domain waveform sequence, calculating the local coating thickness of each scanning point based on the time difference between the first echo peak and the second echo peak, and carrying out dynamic time axis alignment on the original terahertz time-domain waveform sequence by utilizing the local coating thickness to obtain a thickness normalization waveform sequence; The substrate roughness deconvolution module is used for calling a preset non-defective surface scattering reference model, and deconvoluting and filtering the thickness normalized waveform sequence by using the non-defective surface scattering reference model so as to strip a background scattering noise component caused by substrate roughness, thereby obtaining an interface characteristic enhancement signal; The interface dielectric characteristic analysis module is used for carrying out time domain phase polarity analysis and frequency domain spectrum attenuation analysis on the interface characteristic enhancement signal so as to extract dielectric characteristic vectors reflecting the abrupt change state of the interface dielectric constant; And the defect risk assessment imaging module is used for constructing a three-dimensional chromatographic map reflecting the interface bonding integrity based on the dielectric characteristic vector and the thickness of the local coating and outputting a defect detection result under the copper bar coating.
2. The device for nondestructive testing of substrate defects under copper bar plating based on terahertz waves according to claim 1, wherein the terahertz scanning acquisition module comprises: The femtosecond laser pumping unit is used for generating femtosecond laser pulses to excite the terahertz emission source to generate broadband terahertz waves; the reflection type confocal light path unit is used for focusing the broadband terahertz wave at the interface between the coating and the substrate of the copper bar surface to be detected through a preset polyethylene lens and collecting reflection echoes; and the two-dimensional displacement control unit is used for driving the scanning mechanism to drive the reflective confocal light path unit or the copper bar surface to be tested to perform relative movement so as to realize full coverage scanning.
3. The device for nondestructive testing of substrate defects under copper bar plating based on terahertz waves according to claim 1, wherein the time-of-flight dynamic correction module is used for: Positioning two peaks with the largest amplitude absolute value in the original terahertz time-domain waveform sequence as the first echo peak and the second echo peak; Calculating a time-of-flight delay between the first echo peak and the second echo peak; converting the flight time delay into the local coating thickness by combining a preset coating refractive index; And taking the time point of the second echo peak as a reference, translating the original terahertz time-domain waveform sequence on a time axis, and eliminating phase jitter caused by the difference of the local coating thickness.
4. The device for nondestructive inspection of substrate defects under copper bar plating based on terahertz waves according to claim 1, wherein the substrate roughness deconvolution module is used for: adopting a wiener filtering algorithm or a wavelet transformation algorithm, taking the thickness normalized waveform sequence as an input signal, and taking the good product surface scattering reference model as a system response function; A deconvolution operation is performed in the frequency domain, subtracting a scattering component associated with the system response function from the input signal to preserve a reflection component caused by the change in interface dielectric properties as the interface characteristic enhancement signal.
5. The terahertz wave-based copper bar plating layer lower substrate defect nondestructive testing device according to claim 1, wherein the interface dielectric characteristic analysis module is used for: detecting the phase polarity of the interface characteristic enhancement signal at the second echo peak position; If the phase polarity is negative polarity inversion, generating a first numerical identifier as a first dielectric characteristic component to represent good metal contact; If the phase polarity is positive or no flip, generating a second numerical identification as a second dielectric characteristic component to characterize the presence of an air gap or stratification; the first dielectric feature component or the second dielectric feature component is encoded into the dielectric feature vector.
6. The terahertz wave-based copper bar plating layer lower substrate defect nondestructive testing device according to claim 5, wherein the interface dielectric characteristic analysis module is further configured to: Performing fast Fourier transform on the interface characteristic enhancement signal to obtain a frequency domain spectrogram; calculating the amplitude attenuation rate of the frequency domain spectrogram in a specific oxide absorption frequency section; comparing the amplitude attenuation rate with a preset oxidation threshold value; If the amplitude decay rate is greater than the oxidation threshold, generating a third dielectric characteristic component indicative of the presence of oxide inclusions; If the amplitude attenuation rate is smaller than or equal to the oxidation threshold value, generating a normal characteristic component representing no oxide inclusion; the generated feature component is added to the dielectric feature vector.
7. The terahertz wave-based nondestructive testing device for substrate defects under copper bar plating according to claim 1, wherein the defect risk assessment imaging module is used for: Generating the three-dimensional chromatographic map comprising a first layer and a second layer; wherein the first layer is a coating uniformity profile generated based on the local coating thickness; The second layer is an interface-coupled quality thermodynamic diagram generated based on the dielectric feature vector, and a highlight region in the thermodynamic diagram corresponds to a coordinate point where the dielectric feature vector displays an abnormal value.
8. The terahertz wave-based nondestructive testing device for substrate defects under copper bar plating layer according to claim 7, further comprising: the process closed-loop feedback module is used for calculating thickness variance in the coating uniformity distribution diagram and defect area occupation ratio in the interface combined quality thermodynamic diagram; And if the thickness variance is larger than the upper limit value of the preset tolerance range or the defect area ratio is larger than the preset safety threshold value, generating an electroplating process parameter adjustment instruction and sending the electroplating process parameter adjustment instruction to a production line control system.

Description

Terahertz wave-based nondestructive detection device for substrate defects under copper bar plating layer Technical Field The invention relates to the technical field of nondestructive testing, in particular to a terahertz wave-based nondestructive testing device for substrate defects under a copper bar coating. Background In the application scenario of evaluating the reliability of electrical connection of power equipment, a copper bar conductive part guarantees the stability and corrosion resistance of contact resistance by means of a high-quality surface plating process, and a detection system usually needs to combine terahertz wave detection data with a signal processing algorithm to sense the combination state of a plating layer and a substrate interface in real time; For detection of hidden defects under a plating layer, a direct time domain waveform analysis architecture is generally adopted in the prior art, namely, a terahertz time domain spectroscopy system is used for collecting reflected echoes, a peak amplitude threshold method or a simple pulse echo positioning method is used for extracting signal characteristics, the change of echo intensity is directly used as a criterion for evaluating whether layering or foreign matters exist at an interface, although the scheme has certain feasibility in an environment with uniform plating layer thickness and ideal smooth substrate surface, the scheme excessively depends on the absolute amplitude of an original signal and lacks a decoupling mechanism for physical characteristic dimension, when the common plating layer thickness fluctuation and substrate roughness interference in actual industrial production are encountered, the single waveform analysis algorithm is extremely easy to identify phase jitter caused by geometrical thickness difference or background scattering caused by roughness as a defect signal, so that an erroneous detection conclusion is caused, in addition, the analysis method driven by pure time domain is difficult to analyze weak spectrum fingerprints reflecting abrupt changes of dielectric properties of an interface, and difficult to remove system background noise which does not accord with a layered reflection rule, so that masking effect or false alarm easily occurs in a detection process, high-sensitivity and high-confidence interface quality quantification is difficult to support copper bar products, and therefore, how to establish accurate and robust detection performance is realized, and the problem of accuracy and precision of the detection is high is solved is needed. Disclosure of Invention In order to solve the technical problems, the invention provides a terahertz wave-based nondestructive testing device for substrate defects under a copper bar plating layer, which comprises the following specific technical scheme: the terahertz scanning acquisition module is used for controlling the terahertz time-domain spectrum transmitting and receiving unit to perform two-dimensional point-by-point scanning on the copper bar surface to be detected, and acquiring the reflected echo signals of all scanning points to obtain an original terahertz time-domain waveform sequence; The time-of-flight dynamic correction module is used for analyzing a first echo peak of an air and coating interface and a second echo peak of a coating and substrate interface in the original terahertz time-domain waveform sequence, calculating the local coating thickness of each scanning point based on the time difference between the first echo peak and the second echo peak, and carrying out dynamic time axis alignment on the original terahertz time-domain waveform sequence by utilizing the local coating thickness to obtain a thickness normalization waveform sequence; The substrate roughness deconvolution module is used for calling a preset non-defective surface scattering reference model, and deconvoluting and filtering the thickness normalized waveform sequence by using the non-defective surface scattering reference model so as to strip a background scattering noise component caused by substrate roughness, thereby obtaining an interface characteristic enhancement signal; The interface dielectric characteristic analysis module is used for carrying out time domain phase polarity analysis and frequency domain spectrum attenuation analysis on the interface characteristic enhancement signal so as to extract dielectric characteristic vectors reflecting the abrupt change state of the interface dielectric constant; And the defect risk assessment imaging module is used for constructing a three-dimensional chromatographic map reflecting the interface bonding integrity based on the dielectric characteristic vector and the thickness of the local coating and outputting a defect detection result under the copper bar coating. Preferably, the terahertz scanning acquisition module comprises: The femtosecond laser pumping unit is used for generating femtosecond laser pulses to exc