CN-121994148-A - Laser on-line measuring device of copper bar electroplated layer thickness

CN121994148ACN 121994148 ACN121994148 ACN 121994148ACN-121994148-A

Abstract

The invention relates to the technical field of laser detection and nondestructive measurement, in particular to a laser online detection device for thickness of a copper bar electroplated layer, which comprises a modulation excitation step, a coaxial detection step, a signal conversion step, a phase locking demodulation step, a thickness inversion calculation step and a thickness inversion calculation step, wherein the modulation excitation emission module generates a pumping laser beam and induces periodical photo-thermal deformation on the surface of a movable copper bar, the coaxial detection step enables the coaxial detection laser beam and the pumping laser beam to be coaxially focused and collect reflected interference light signals, the signal conversion step enables the light signals to be converted into time domain electric signals containing mechanical vibration noise by the photoelectric signal conversion module, the phase locking demodulation step enables a quadrature phase locking demodulation module to conduct frequency domain quadrature operation to strip the noise and extract a phase lag value, and the thickness inversion calculation module calculates a real-time thickness value based on a phase-thickness mapping model.

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: 20260209

Claims (8)

1. Laser on-line measuring device of copper bar electroplated layer thickness, its characterized in that includes: the modulation excitation emission module is used for generating a pumping laser beam with a preset modulation frequency and projecting the pumping laser beam to the surface of the copper bar in motion so as to induce periodic photo-thermal deformation in a coating on the surface of the copper bar; The coaxial interference detection module is used for emitting a detection laser beam with constant power, coaxially focusing the detection laser beam and the pumping laser beam on the same point on the surface of the copper bar, and collecting a reflection interference light signal modulated by the photo-thermal deformation; the photoelectric signal conversion module is used for converting the reflected interference optical signal into a time domain electric signal, and the time domain electric signal comprises a photo-thermal deformation signal component and a mechanical vibration noise component; The quadrature phase-locked demodulation module is used for carrying out frequency domain quadrature operation on the time domain electric signal based on the preset modulation frequency so as to strip the mechanical vibration noise component and extract a phase lag value relative to the pumping laser beam; and the thickness inversion calculation module is used for calculating the real-time thickness value of the copper bar electroplated layer through a preset phase-thickness mapping model based on the phase lag value.
2. The laser online detection device for thickness of copper bar plating layer according to claim 1, wherein the modulation excitation emission module is specifically configured to: driving a laser to generate a laser beam with the intensity changing according to a sine wave rule as the pumping laser beam; and setting the preset modulation frequency to be a value larger than the mechanical resonance frequency of the copper bar so as to ensure the separation of the photothermal deformation signal component and the mechanical vibration noise component in a frequency domain.
3. The laser on-line detection device for copper bar plating layer thickness according to claim 1, wherein the coaxial interference detection module comprises: A dichroic mirror unit for transmitting the pumping laser beam and reflecting the detection laser beam to realize spatial beam combination of the pumping laser beam and the detection laser beam; and the focusing lens group is used for converging the laser after beam combination to a micron-sized light spot area on the surface of the copper bar and receiving the detection light carrying the phase information and reflected back by the surface of the copper bar.
4. The laser online detection device for thickness of copper bar plating layer according to claim 1, wherein the quadrature phase-locked demodulation module is specifically configured to: generating a reference sine signal and a reference cosine signal which are the same frequency as the preset modulation frequency and phase-locked; multiplying the time domain electric signal with the reference sine signal and the reference cosine signal respectively, and performing low-pass filtering integral processing on the operation result to obtain an in-phase component value and a quadrature component value; And calculating the phase lag value by using an arc tangent function based on the in-phase component value and the quadrature component value.
5. The laser online detection device for thickness of copper bar plating layer according to claim 4, wherein said quadrature phase-locked demodulation module is further configured to: In the low-pass filtering integration process, a signal component having a frequency lower than the cut-off frequency is filtered out by a low-pass filter having a cut-off frequency lower than the preset modulation frequency, and the signal component is removed as the mechanical vibration noise component.
6. The laser online detection device for thickness of copper bar electroplated layer according to claim 1, wherein the thickness inversion calculation module is specifically configured to: acquiring a thermal diffusivity parameter of a base material and a thermal diffusivity parameter of a coating material of a current tested copper bar; calling a pre-calibrated phase-thickness association curve corresponding to the parameter from a preset material attribute database as the phase-thickness mapping model; Substituting the phase lag value into the phase-thickness correlation curve to perform interpolation calculation so as to obtain the real-time thickness value.
7. The laser on-line detection device for thickness of copper bar plating layer according to claim 1, further comprising: The electroplating process state monitoring module is configured to compare the real-time thickness value with a preset target thickness range, wherein the target thickness range is defined by a preset lower limit value and a preset upper limit value; if the real-time thickness value is smaller than the preset lower limit value, generating an underthickness warning data packet for prompting current increase and sending the underthickness warning data packet to a controller; If the real-time thickness value is larger than the preset upper limit value, an excessive thickness warning data packet for prompting current reduction is generated and sent to a controller; and if the real-time thickness value is between the preset lower limit value and the preset upper limit value, generating a state mark with qualified thickness.
8. The laser online detection device for the thickness of a copper bar electroplated layer according to claim 1, wherein the phase-thickness mapping model is a model which is pre-constructed based on physical conditions that the difference between the thermal diffusivity of a base material and the thermal diffusivity of a coating material is larger than a preset difference threshold.

Description

Laser on-line measuring device of copper bar electroplated layer thickness Technical Field The invention relates to the technical field of laser detection and nondestructive measurement, in particular to a laser online detection device for the thickness of a copper bar electroplated layer. Background In the industrial production scene of the copper bar surface electroplating process, the production line relies on accurate plating thickness parameters to ensure the conductivity and corrosion resistance of the product, and a quality control system is usually required to dynamically adjust the electroplating current and the transmission speed by combining real-time detection data; Aiming at the online calibration of the thickness of a coating, the prior proposal generally adopts a direct geometric measurement architecture, namely, a triangulation laser displacement sensor or a vision camera is used for collecting copper bar surface profile data, the geometric operation is utilized for directly extracting the height difference relative to a reference plane as a thickness truth value, although the proposal has certain feasibility in static or ideal stable environment, the proposal is excessively dependent on the geometric space position of an object to be measured and lacks the logic constraint of a frequency domain physical model, when encountering a complex dynamic environment caused by a high-speed conveyor belt, the geometric measurement algorithm is extremely easy to mistakenly identify environmental noise such as mechanical vibration, transmission jitter and the like of the copper bar body as an effective thickness signal, thereby leading to wrong parameter input, in addition, the measurement mode driven by pure geometric space is extremely sensitive to microscopic jitter of the surface of the object to be measured, and difficult to eliminate abnormal observation values which do not accord with a photo-thermal response rule, so that data drift or signal-to-noise ratio is easy to occur in the detection process, and real-time closed loop control of high frequency and micrometer precision is difficult to support a production line, therefore, how to establish a detection mechanism with the capability of frequency domain analysis and physical field verification is needed to improve the real-time interference resistance of the coating while effectively mechanical vibration interference noise. Disclosure of Invention In order to solve the technical problems, the invention provides a laser online detection device for the thickness of a copper bar electroplated layer, and specifically, the technical scheme of the invention comprises the following steps: the modulation excitation emission module is used for generating a pumping laser beam with a preset modulation frequency and projecting the pumping laser beam to the surface of the copper bar in motion so as to induce periodic photo-thermal deformation in a coating on the surface of the copper bar; The coaxial interference detection module is used for emitting a detection laser beam with constant power, coaxially focusing the detection laser beam and the pumping laser beam on the same point on the surface of the copper bar, and collecting a reflection interference light signal modulated by the photo-thermal deformation; the photoelectric signal conversion module is used for converting the reflected interference optical signal into a time domain electric signal, and the time domain electric signal comprises a photo-thermal deformation signal component and a mechanical vibration noise component; The quadrature phase-locked demodulation module is used for carrying out frequency domain quadrature operation on the time domain electric signal based on the preset modulation frequency so as to strip the mechanical vibration noise component and extract a phase lag value relative to the pumping laser beam; and the thickness inversion calculation module is used for calculating the real-time thickness value of the copper bar electroplated layer through a preset phase-thickness mapping model based on the phase lag value. Preferably, the modulation excitation transmitting module is specifically configured to: driving a laser to generate a laser beam with the intensity changing according to a sine wave rule as the pumping laser beam; and setting the preset modulation frequency to be a value larger than the mechanical resonance frequency of the copper bar so as to ensure the separation of the photothermal deformation signal component and the mechanical vibration noise component in a frequency domain. Preferably, the coaxial interference detection module includes: A dichroic mirror unit for transmitting the pumping laser beam and reflecting the detection laser beam to realize spatial beam combination of the pumping laser beam and the detection laser beam; and the focusing lens group is used for converging the laser after beam combination to a micron-sized light spot area on the surf