Method, device and equipment for measuring size and warping degree of ceramic substrate for heat dissipation of high-power power electronic module and medium

Abstract

The invention relates to a method, a device, equipment and a medium for measuring the size and the warping degree of a ceramic substrate for heat dissipation of a high-power power electronic module, and the method comprises the following steps: S1, placing the ceramic substrate on a horizontal plane, scanning the surface of the ceramic substrate through a 3D line laser measuring instrument, and obtaining a height image of the surface of the ceramic substrate; s2, dividing the height image into a ceramic substrate area and a background horizontal plane area; s3, the width and height of the ceramic substrate are calculated after the ceramic substrate area is rotated and straightened; and S4, according to the height image, measuring the position of the highest point of the ceramic substrate, the height value of the highest point and the height value of the horizontal plane of the background horizontal plane area, and measuring the thickness value of the highest point of the ceramic substrate by using a correlation laser displacement meter. And calculating the warping degree of the ceramic substrate according to the height value and the thickness value of the highest point of the ceramic substrate and the height value of the horizontal plane. The warping degree, the size and the thickness of the ceramic substrate can be accurately measured, and the product performance is guaranteed.

Description

Technical Field

[0001] The present invention relates to the field of precision measurement technology, and in particular to a method, device, equipment and medium for measuring the size and warpage of a ceramic substrate used for heat dissipation of a high-power power electronic module. Background Art

[0002] In recent years, with the rapid development of industries such as new energy vehicles, aerospace, energy storage, and smart grids, high-voltage, high-power power electronic modules have been widely used. When these modules operate under high voltage and high power conditions for long periods of time, their heat dissipation performance is crucial to their stability and reliability. If heat cannot be dissipated promptly, it can easily lead to bond wire debonding or melting, causing module failure. Consequently, the requirements for heat dissipation performance in power electronic modules are becoming increasingly stringent. The current carrying and heat dissipation of high-power power electronic modules primarily rely on the module's ceramic copper-clad substrate, a composite material composed of a "copper-ceramic-copper" structure. Ceramic substrates not only offer excellent properties such as high heat dissipation, high insulation, and high mechanical strength, but also have a thermal expansion coefficient that matches the chip well. They also combine the high current carrying capacity and high thermal conductivity of oxygen-free copper, making them a key packaging material for power electronic modules.

[0003] Ceramic substrates exhibit ultra-high mechanical strength and fracture toughness, while their physical properties include ultra-high thermal conductivity, low thermal expansion coefficient, low dielectric constant, and high resistance to electrical penetration. Furthermore, they exhibit excellent solderability and a thermal expansion coefficient similar to that of semiconductor materials, making them easy to integrate with chips. However, key specifications such as the width, height, thickness, and warpage of ceramic substrates have a significant impact on the performance of packaged power electronic modules. When the size and thickness of a ceramic substrate deviate from standard process requirements, or when warping occurs due to stress during processing or use, significant stress is generated at the copper-ceramic interface, leading to ceramic cracking or copper layer delamination, ultimately causing the entire power electronic module to fail. Therefore, accurate measurement of the size, thickness, and warpage of ceramic substrates is particularly important.

[0004] Currently, the width, height, thickness, and warpage of ceramic substrates are primarily measured manually. However, manual measurement suffers from poor accuracy and low efficiency, making it difficult to meet the high-precision and high-efficiency demands of modern industry. Furthermore, manual measurement is susceptible to subjective operator influences, which can lead to inconsistent measurement results and increase the risk of defective products. To address these issues, the industry is increasingly focusing on using precision measuring instruments combined with image processing technology to build high-precision automated measurement systems to automatically measure the size, thickness, and warpage of ceramic substrates. This approach not only significantly improves measurement accuracy but also effectively reduces the flow of defective products, eliminates interference from human factors, and reduces waste of human resources, thereby saving companies operating costs and improving customer satisfaction.

[0005] However, existing technologies still face several pressing technical challenges. For example, how to accurately extract the ceramic substrate region from a complex background using efficient image processing techniques, how to eliminate the influence of ceramic substrate tilt on dimensional measurements during the measurement process, and how to accurately calculate the warpage of the ceramic substrate by integrating multiple measurement data. To address these challenges, the present invention proposes a high-precision automated measurement method based on precision measuring instruments and image processing technology. This method aims to address these shortcomings and provide reliable technical support for the quality control of ceramic substrates. Summary of the Invention

[0006] One of the main objectives of the present invention is to provide a method for measuring the size and warpage of ceramic substrates used for heat dissipation in high-power power electronic modules. Based on the product characteristics and the actual production needs of customers, the width, height, thickness, and warpage deformation of the ceramic substrate are measured to ensure product performance. This method solves the shortcomings of existing ceramic substrate measurement methods such as poor accuracy, low efficiency, and high human interference.

[0007] The present invention achieves the above-mentioned object through the following technical solution: A method for measuring the size and warpage of a ceramic substrate for heat dissipation of a high-power power electronic module, comprising the following steps: S1. Place the ceramic substrate on a horizontal surface and use a 3D line laser measuring instrument to scan the surface of the ceramic substrate to obtain a height image of the surface of the ceramic substrate; S2, dividing the height image into a ceramic substrate area and a background horizontal plane area; S3, rotating and straightening the ceramic substrate area and calculating the width and height of the ceramic substrate; S4. Measure the position of the highest point of the ceramic substrate, the height Hm of the highest point, and the horizontal plane height H0 of the background horizontal plane area based on the height image; use a reflected laser displacement meter to measure the thickness Tm of the highest point of the ceramic substrate; and calculate the warpage Warp of the ceramic substrate based on the height Hm, thickness Tm, and horizontal plane height H0 of the highest point of the ceramic substrate.

[0008] Furthermore, step S2 includes the following steps: S21, using a Gaussian filter to smooth and remove noise from the height image; S22, calculating the gradient and direction of each pixel of the height image, and filtering each pixel to retain the pixel with the extreme gradient. The pixel position of the local extreme value is the edge candidate point; S23, setting a threshold, edge candidate points with absolute values ​​greater than the threshold are regarded as image edges, and image edge pixels are classified into strong edges, weak edges, and non-edges; S24, retain strong edge pixels and discard non-edge pixels; S25, analyzing the positional relationship between weak edges and strong edges, and performing secondary screening on weak edges; S26 , jointly processing the retained weak edge pixels and the strong edge pixels to form a complete edge contour line, thereby obtaining a ceramic substrate area, and the remaining area is a background horizontal plane area.

[0009] Furthermore, step S3 includes the following steps: S31, record the ceramic substrate region as Region, calculate the row coordinate Row, column coordinate Column of the center point of Region and the tilt angle Phi of the circumscribed rectangle; S32. Define an affine matrix with (Column, Row) as the rotation center and -Phi as the rotation angle, perform an affine transformation on Region, and obtain the rotated and rectified ceramic substrate region, which is recorded as RotateRegion. S33, calculating the size of RotateRegion, and obtaining the number of pixels Xpixel occupied by the width and the number of pixels Ypixel occupied by the height of the ceramic substrate; S34. Calculate the width and height of the ceramic substrate based on Xpixel, Ypixel, and the pixel accuracy Xaccuracy in the X direction and Yaccuracy in the Y direction of the 3D line laser measuring instrument: Width = Xpixel * Xaccuracy; Height = Ypixel * Yaccuracy.

[0010] Furthermore, step S4 includes the following steps: S41, traversing the pixel value of each pixel point in the ceramic substrate area, the pixel value is the height value of the position on the ceramic substrate corresponding to the pixel point, and the position with the largest pixel value is the position with the highest warpage on the ceramic substrate; S42, using binarization to extract the highest pixel, and grouping the suspected pixels with the same height value range together as a suspected area; S43, using Blob analysis to extract and mark the connected domains of the suspected area, and each marked Blob represents a suspected target; S44. Screen suspected targets based on width, height, and area features. The largest area that is ultimately retained is the highest area of ​​the ceramic substrate. The center point (Xm, Ym) of the highest area is the highest point of the ceramic substrate. The pixel value at (Xm, Ym) is the height value Hm of the highest point of the ceramic substrate. S45, traversing the pixel value of each pixel point in the background horizontal plane area, the pixel value is the height value of the background horizontal plane position corresponding to the pixel point, calculating the average height of the entire background horizontal plane, and obtaining the horizontal plane height value H0 of the background horizontal plane area; S46. Use a laser displacement meter to measure the thickness Tm at (Xm, Ym); S47. Calculate the warpage of the ceramic substrate: Warp = (Hm - Tm - H0) / Height.

[0011] The method for measuring the size and warpage of a ceramic substrate for heat dissipation of a high-power power electronic module according to claim 1 is characterized in that the method for measuring the thickness value using a through-beam laser displacement meter comprises the following steps: S461. Provide a hollow fixture and a thickness calibration plate. Set an upper laser displacement meter above the hollow fixture and a lower laser displacement meter below the hollow fixture. The thickness of the thickness calibration plate is t ; S462. Place a thickness calibration plate on a hollow fixture, randomly select several measurement points on the thickness calibration plate, and for each measurement point on the thickness calibration plate, use the upper laser displacement meter to measure the distance d1 to the upper surface of the thickness calibration plate, and use the lower laser displacement meter to measure the distance d2 to the lower surface of the thickness calibration plate; S463. For each measuring point on the thickness calibration plate, calculate the single-point installation spacing z = d1 + d2 + t between the upper laser displacement meter and the lower laser displacement meter, and take the average value to obtain the installation spacing Z between the upper laser displacement meter and the lower laser displacement meter. S464, placing the ceramic substrate on the hollow jig, and for each measuring point on the ceramic substrate, measuring the upper distance D1 to the upper surface of the measuring point using the upper laser displacement meter, and measuring the lower distance D2 to the lower surface of the measuring point using the lower laser displacement meter; S465. Calculate the thickness value T = Z - (D1 + D2) at each measuring point on the ceramic substrate, and take the average of the thickness values ​​of all measuring points to obtain the average thickness value of the ceramic substrate.

[0012] Furthermore, the method further includes: step S5, measuring the thickness of the ceramic substrate using a through-beam laser displacement meter, including the following steps: S51. Provide a hollow jig and a thickness calibration plate, and set an upper laser displacement meter above the hollow jig and a lower laser displacement meter below the hollow jig; S52, calculating the installation distance Z between the upper laser displacement meter and the lower laser displacement meter using the thickness calibration plate; S53, placing the ceramic substrate on the hollow fixture, and for each measuring point on the ceramic substrate, measuring the upper distance D1 to the upper surface of the measuring point using the upper laser displacement meter, and measuring the lower distance D2 to the lower surface of the measuring point using the lower laser displacement meter; S54. Calculate the thickness value T = Z - (D1 + D2) at each measuring point, and take the average of the thickness values ​​of all measuring points to obtain the average thickness value of the ceramic substrate.

[0013] Furthermore, step S52 includes the following steps: S521. Place the thickness calibration plate on the hollow fixture, use the upper laser displacement meter to measure the distance d1 to the upper surface of the thickness calibration plate, and use the lower laser displacement meter to measure the distance d2 to the lower surface of the thickness calibration plate; S522. Calculate the single-point installation spacing z = d1 + d2 + t between the upper laser displacement meter and the lower laser displacement meter based on the thickness t of the calibration plate and the measured distances d1 and d2. S523. Randomly select several measurement points on the thickness calibration plate, repeat steps S521 to S522, obtain several single-point installation spacings z, and take the average value to obtain the installation spacing Z between the upper laser displacement meter and the lower laser displacement meter.

[0014] Another object of the present invention is to provide a device for measuring the size and warpage of a ceramic substrate used for heat dissipation in a high-power power electronic module, comprising: Hollow jig; An upper laser displacement meter and a lower laser displacement meter are arranged on the upper and lower sides of the hollow jig relative to each other; the upper laser displacement meter is configured to measure the distance to the upper surface of an object placed on the hollow jig, and the lower laser displacement meter is configured to measure the distance to the lower surface of an object placed on the hollow jig; a thickness calibration plate having a thickness of t and configured to assist in calculating the installation spacing Z between the upper laser displacement meter and the lower laser displacement meter; a 3D line laser measuring instrument configured to obtain a height image of a surface of a measured object; The first calculation module includes a first relational expression, a second relational expression, and a third relational expression. The first relational expression is configured to calculate the single-point installation spacing between the upper laser displacement meter and the lower laser displacement meter by summing the distance d1 measured by the upper laser displacement meter to the upper surface of the thickness calibration plate placed in the hollow fixture, the distance d2 measured by the lower laser displacement meter to the lower surface of the thickness calibration plate, and the thickness t of the thickness calibration plate. The second relational expression is configured to calculate the installation spacing Z between the upper laser displacement meter and the lower laser displacement meter by taking the average of multiple single-point installation spacings. The third relational expression is configured to calculate the thickness value T of the ceramic substrate at the measurement point on the hollow fixture = Z-(D1+D2) based on the installation spacing Z, the upper distance D1 measured by the upper laser displacement meter to the upper surface of the ceramic substrate at the measurement point, and the lower distance D2 measured by the lower laser displacement meter to the lower surface of the ceramic substrate at the measurement point. a first processing module configured to divide the height image into a ceramic substrate region and a background horizontal plane region; A second processing module is configured to rotate and straighten the ceramic substrate region to obtain a rotated and straightened ceramic substrate region, which is recorded as RotateRegion; The second calculation module includes a fourth relationship, wherein the fourth relationship is configured to calculate the width of the ceramic substrate Width = Xpixel * Xaccuracy and the height Height = Ypixel * Yaccuracy based on the number of pixels occupied by the width Xpixel and the number of pixels occupied by the height Ypixel of the RotateRegion, and the pixel accuracy Xaccuracy in the X direction and the pixel accuracy Yaccuracy in the Y direction of the 3D line laser measuring instrument; The third processing module is configured to: traverse the pixel value of each pixel point in the ceramic substrate area, extract the highest area, and record the center point (Xm, Ym) of the highest area as the position of the highest point of the ceramic substrate, and the pixel value at (Xm, Ym) is the height value Hm of the highest point of the ceramic substrate; traverse the pixel value of each pixel point in the background horizontal plane area, calculate the height average of the entire background horizontal plane, and obtain the average height value H0 of the background horizontal plane; The third calculation module includes a fifth relationship, which is configured to calculate the warpage of the ceramic substrate Warp = (Hm - Tm - H0) / Height based on the height value Hm at the highest point (Xm, Ym) of the ceramic substrate, the thickness value Tm at the highest point (Xm, Ym) calculated by the first calculation module, and the average height value H0 of the background horizontal plane area.

[0015] Another object of the present invention is to provide a device for measuring the size and warpage of a ceramic substrate used for heat dissipation in a high-power power electronic module, comprising: memory for storing computer programs; The processor is configured to execute the computer program to implement the above-mentioned method for measuring the size and warpage of a ceramic substrate for heat dissipation of a high-power power electronic module.

[0016] Another object of the present invention is to provide a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the computer program implements the above-mentioned method for measuring the size and warpage of a ceramic substrate for heat dissipation of a high-power power electronic module.

[0017] The present invention uses a standard thickness calibration plate to calculate the installation spacing of a through-beam laser displacement meter; uses a laser displacement meter to measure the thickness of a ceramic substrate; uses a 3D line laser measuring instrument to scan the surface of the ceramic substrate to obtain a height image of the ceramic substrate surface; uses image enhancement and edge extraction methods to divide the image area of ​​the height image into a ceramic substrate area and a background horizontal plane area; uses affine transformation to rotate and straighten the ceramic substrate area according to the inclination angle of the ceramic substrate to prevent the inclination of the ceramic substrate from affecting the accuracy of the dimensional measurement result; calculates the width and height of the straightened ceramic substrate; measures the position and height value of the highest point of the ceramic substrate according to the height image of the ceramic substrate, and uses a through-beam laser displacement meter to measure the thickness value of the highest point of the ceramic substrate; and calculates the warpage of the ceramic substrate according to the thickness value, height value and horizontal plane height value of the highest point of the ceramic substrate.

[0018] Compared with the existing technology, the beneficial effects of the method, device, equipment and medium for measuring the size and warpage of ceramic substrates used for heat dissipation of high-power power electronic modules of the present invention are: by using precision measuring instruments in combination with image processing technology to form a high-precision automated measurement system, high-precision and high-efficiency detection of key parameters of the ceramic substrate is achieved; first, a laser displacement meter is used to measure the thickness of the ceramic substrate, and then a 3D line laser measuring instrument is used to measure the size of the ceramic substrate and the height difference from the horizontal plane, and the warpage of the ceramic substrate is calculated by the height difference between the ceramic substrate and the horizontal plane and the thickness value of the ceramic substrate itself. Compared with the method of using a single measuring instrument to measure thickness or warpage, this method improves the measurement accuracy. Compared with manual measurement, the automated measurement technology reduces the outflow of defects, eliminates the interference of human factors, reduces the waste of human resources, and effectively improves customer satisfaction with the product while saving the operating costs of the enterprise. Specifically: (1) High-precision thickness measurement is achieved: the installation distance Z between the upper and lower laser displacement meters is calculated in conjunction with a thickness calibration plate. The installation distance between the upper and lower laser displacement meters is further used to calculate the thickness T of the ceramic substrate, and the difference method (T = Z - (D1 + D2)) is used to eliminate the system error. The thickness measurement resolution reaches the micron level, and the detection accuracy is high. (2) Accurate segmentation of the ceramic substrate area improves the accuracy of ceramic substrate size detection: Combined with 3D line laser triangulation to generate a height image, the substrate contour is extracted through Gaussian filtering denoising and Canny edge detection, effectively distinguishing the ceramic substrate area from the background horizontal area, with an edge positioning accuracy of ±5μm, overcoming the misjudgment problem caused by the close height between the substrate and the background in traditional visual methods; (3) Use tilt correction for size calculation: Automatically rotate and straighten the ceramic substrate area based on affine transformation, and calculate the actual size of the ceramic substrate in combination with pixel accuracy conversion, eliminating the influence of substrate placement tilt on size measurement. The width / height measurement error is ≤0.02%, which is applicable to rectangular / special-shaped substrates of different specifications; (4) Dynamic evaluation of warpage: On the premise of accurately segmenting the ceramic substrate area, the highest point of the ceramic substrate area is located through Blob analysis, and the thickness value of the highest point is obtained by linkage with a laser displacement meter. Combined with the average height of the reference horizontal plane, the relative warpage (△H = Hm - Tm - H0) and the warpage (Warp = △H / Height) are calculated, realizing a fully automatic quantitative evaluation of the warpage with a detection sensitivity of 0.001mm / m, providing data support for the optimization of the heat dissipation performance of the IGBT module. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of a process flow of an embodiment of the present invention; Figure 2 Schematic diagram of the principle of laser displacement measurement in an embodiment of the present invention; Figure 3 Schematic diagram of the measurement principle of a 3D line laser measuring instrument in an embodiment of the present invention; Figure 4 Schematic diagram of the process of dividing a height image into a ceramic substrate area and a background horizontal plane area in an embodiment of the present invention; Figure 5 Schematic diagram of the steps for calculating the width and height of the ceramic substrate after rotation and alignment according to an embodiment of the present invention; Figure 6 Schematic diagram of the process of calculating the warpage of a ceramic substrate according to the height image in an embodiment of the present invention; Figure 7 Schematic diagram of the process of measuring thickness using a laser displacement meter according to an embodiment of the present invention. DETAILED DESCRIPTION

[0020] To further illustrate the technical means and effectiveness of the present invention in achieving its intended objectives, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effectiveness of a method for measuring the size and warpage of a ceramic substrate used for heat dissipation in high-power power electronic modules, as proposed by the present invention. In the following description, references to different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics of one or more embodiments may be combined in any suitable manner.

[0021] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0022] Example 1: The following describes in detail a method for measuring the size and warpage of a ceramic substrate for heat dissipation of a high-power electronic module provided by the present invention with reference to the accompanying drawings.

[0023] See also Figure 1-Figure 7 , which shows a flowchart of a method for measuring the size and warpage of a ceramic substrate for heat dissipation of a high-power electronic module provided by one embodiment of the present invention, the method comprising the following steps: Step S001: Install the upper and lower opposing laser displacement meters, calculate the installation distance Z of the opposing laser displacement meters using a standard thickness calibration plate, and measure the thickness T of the ceramic substrate using the opposing laser displacement meters.

[0024] In semiconductor technology, ceramic substrates primarily serve as carriers for various power electronic device chips. Copper is clad on both sides of a ceramic substrate, creating a composite material with a "copper-ceramic-copper" structure. In the packaging of IGBT modules, the copper-clad ceramic substrate with the IGBT chip is soldered to the module baseplate, forming a heat dissipation channel for the IGBT chip. The ceramic substrate absorbs the chip's heat and conducts it to a heat sink, enabling heat exchange between the chip and the outside world.

[0025] In this embodiment, upper and lower opposing laser displacement meters are installed, and the installation spacing Z of the opposing laser displacement meters is calculated using a standard thickness calibration plate. The thickness value T of the ceramic substrate is measured using the opposing laser displacement meter, specifically including: A laser displacement meter is mounted above and below the hollow fixture, with the laser axes of the two laser displacement meters perpendicular to the horizontal plane of the hollow fixture. The laser in the laser displacement meter emits a beam of polychromatic light with a wide spectrum λ1 - λn. The incident polychromatic light is decomposed into monochromatic light of different wavelengths by the dispersion objective lens. Due to the difference in refractive index, light of different wavelengths will focus at different positions along the optical axis, forming a continuous spectral distribution. The axial distance between a single pixel of wavelength λi and the lens is d(λi). Ideally, the relationship between wavelength and displacement satisfies the following equation: ; in, k is the proportional coefficient, indicating the axial distance With wavelength λi The rate of change, m is a constant term, representing the λi =0, the theoretical axial distance between a single pixel and the lens; only monochromatic light of a specific wavelength can be focused on the surface of the object being measured and reflected back to the optical system. The reflected light passes through the pinhole filter and is detected and analyzed by the spectrometer. The pinhole filter will filter out most of the spectral flux of the out-of-focus reflection, ensuring that only the light perfectly focused on the surface of the object being measured passes through. The internal spectrometer deconstructs the wavelength of the received reflected light and determines its central wavelength, and inversely infers the distance between the surface of the object being measured and the laser displacement meter. D , thereby realizing the ranging function, its principle is as follows Figure 2 shown.

[0026] Place the calibration plate of standard thickness on the hollow fixture. The sum of the distance d1 from the upper laser displacement meter to the upper surface of the calibration plate, the distance d2 from the lower laser displacement meter to the lower surface of the calibration plate, and the thickness t of the calibration plate is the installation distance Z of the upper and lower laser displacement meters. Z = d1 + d2 + t; Randomly select several measurement points on the calibration plate, repeat the above steps, calculate multiple times and take the average value to obtain the installation distance Z of the upper and lower laser displacement meters to avoid error interference.

[0027] Place the ceramic substrate on the hollow fixture, select a thickness measurement point, and measure the distance D1 from the upper laser displacement meter to the upper surface of the point, and the distance D2 from the lower laser displacement meter to the lower surface of the point. Based on the installation spacing Z of the upper and lower laser displacement meters and the measured upper distance D1 and lower distance D2, the thickness of the ceramic substrate at that point can be calculated: T = Z - (D1 + D2).

[0028] According to the requirements for measuring the thickness of the ceramic substrate, the thickness values ​​at all measuring points are measured, and then the thickness T of the ceramic substrate is obtained by taking the average.

[0029] So far, the thickness T of the ceramic substrate has been measured through the above steps. This step can also be used to measure the thickness value of any point on the ceramic substrate.

[0030] Step S002: Use a 3D line laser measuring instrument to scan the surface of the object to be measured (in this embodiment, the object to be measured is a ceramic substrate to be measured) to obtain a height image of the ceramic substrate surface. Then, use image enhancement and edge extraction methods on the height image to divide the image area into the ceramic substrate area and the background horizontal plane area. Specifically: The scanning field of view of a 3D line laser measuring instrument is generally larger than the actual size of the object to be measured. Therefore, the height image obtained not only includes the ceramic substrate area, but also includes the background horizontal surface and other noise interference.

[0031] Place the ceramic substrate on a horizontal surface. The laser in the 3D line laser measuring instrument emits a line laser vertically to the surface of the object to be measured. The axial direction of the incident light coincides with the normal direction of the plane of the object to be measured. The incident light is diffusely reflected on the surface of the object to be measured to form a laser spot. The imaging lens inside the 3D line laser measuring instrument collects the reflected light and finally forms an imaging spot on the internal image sensor. Move the object to be measured at a constant speed in the horizontal direction. When the surface of the object to be measured fluctuates, the plane to be measured is displaced along the axis of the laser. At this time, the position of the imaging spot on the image sensor also moves, and the displacement of the plane to be measured and the displacement of the imaging spot are one-to-one mapped. The principle is as follows: Figure 3 shown.

[0032] Specifically, draw a perpendicular line to L through point A, with its foot at point B; Draw a perpendicular line from the extended line of l, and the foot of the perpendicular is Among them, △AOB and △ resemblance.

[0033] According to the principle of similar triangles, we can conclude that ; According to the principle of trigonometric function, we can conclude that ; ; ; ; From the above relationship, we can conclude that ; It can be concluded that the mapping relationship between the displacement of the measured plane and the displacement of the imaging spot is: , Among them, L, l, α, and β are constants, which are determined by the selection of the 3D line laser measuring instrument.

[0034] After scanning the entire surface of the object to be measured, the actual displacement distance between each position on the surface of the object to be measured and the reference plane can be calculated by the displacement distance of the imaging spot, thereby generating an image of the height of the surface of the object to be measured.

[0035] Since the thickness of the ceramic substrate is small, when it is placed on the background horizontal plane, its height is close to the horizontal plane. The height information of the ceramic substrate surface and the horizontal plane in the height map Image obtained after scanning by the 3D line laser measuring instrument is close, making it difficult to accurately locate the edge of the ceramic substrate. Therefore, it is necessary to process the original height image Image to make the edge between the ceramic substrate and the horizontal plane clear and easy to extract.

[0036] A Gaussian frequency domain filter Filter of specific specifications and resolution is generated according to the size of the original height image Image, and a convolution operation is performed on the height image Image using the Gaussian filter. Specifically, the Filter scans each pixel on the Image and replaces the original value of the pixel with the weighted average of all pixel values ​​in the neighborhood around the scanned pixel and the Filter. The Gaussian filter can smooth and denoise the image, effectively reducing the interference of background noise.

[0037] Specifically, a 3 * 3 horizontal convolution kernel Gx and a 3 * 3 vertical convolution kernel Gy are generated, and convolution operations are performed on the image respectively. The gradient of the image in the horizontal and vertical directions is calculated. The overall strength and direction of the edge can be calculated based on the directional gradient. Each pixel point is filtered and the pixel points with extreme gradients are retained. The pixel positions with local extreme values ​​are edge candidate points.

[0038] A threshold is set, and edge candidates with an absolute value greater than the threshold are considered image edges. Edge pixels are then classified as true edges (strong edges), suspected edges (weak edges), and non-edges. Strong edge pixels are retained while non-edge pixels are discarded. Weak edges may be true edges or noise interference. By analyzing the positional relationship between weak and strong edges, weak edges are screened again. The retained weak edge pixels are combined with the strong edge pixels to form a complete edge outline. The area enclosed by the edge outline is the ceramic substrate area, and the remaining area is the background horizontal surface area.

[0039] So far, the height image of the ceramic substrate surface is obtained through the above method, and the image area is divided into the ceramic substrate area and the background horizontal plane area.

[0040] Step S003: According to the tilt angle of the ceramic substrate, use affine transformation to rotate and straighten the ceramic substrate area to prevent the tilt of the ceramic substrate from affecting the accuracy of the size measurement results, and calculate the width Width and height Height of the straightened ceramic substrate. Specifically: Ceramic substrates are generally rectangular in shape. Calculate the row and column coordinates of the center point of the ceramic substrate region, Region, as well as the tilt angle Phi of the circumscribed rectangle. Define an affine matrix with (Column, Row) as the rotation center and -Phi as the rotation angle. Apply an affine transformation to Region to obtain the rotated and rectified RotateRegion.

[0041] Specifically, each point (x, y) on the image is rotated by an angle of -Phi around the rotation center (Column, Row) to obtain a new point (x', y'). x' = Row+ (x - Row) * cos(-Phi) - (y - Column) * sin(-Phi); y' = Column+ (x - Row) * sin(-Phi) + (y - Column) * cos(-Phi); Use affine transformation to rotate and straighten Region to obtain RotateRegion to prevent the tilt of the ceramic substrate from affecting the accuracy of the size measurement results.

[0042] Calculate the size of RotateRegion to obtain the number of pixels Xpixel and Ypixel occupied by the width and height of the ceramic substrate respectively. Based on Xpixel and Ypixel and the pixel accuracy Xaccuracy and Yaccuracy of the 3D line laser measuring instrument in the X and Y directions, calculate the width Width and height Height of the ceramic substrate: Width = Xpixel * Xaccuracy; Height = Ypixel * Yaccuracy.

[0043] So far, the width Width and height Height of the ceramic substrate have been measured by the above method.

[0044] Step S004: Based on the height image of the ceramic substrate, the position and height of the highest point of the ceramic substrate are measured, and the thickness of the highest point of the ceramic substrate is measured using a laser displacement meter. The warpage of the ceramic substrate is calculated based on the height, thickness and horizontal height of the highest point of the ceramic substrate. Specifically: The pixel value of each pixel point in the ceramic substrate area is traversed. The pixel value represents the height value of the position on the ceramic substrate corresponding to the pixel point. The position with the largest pixel value is the position with the highest warpage on the ceramic substrate.

[0045] Binarization is used to extract the highest pixel. Suspected pixels with the same height range are grouped together to form a suspected region. Blob analysis is then used to extract and label the connected domains within the suspected region. Each labeled blob represents a suspected target, which is then screened based on features such as width, height, and area. The largest region that remains is the highest region of the ceramic substrate. The center point (Xm, Ym) of the highest region is the location of the highest point on the ceramic substrate, and the pixel value at (Xm, Ym) is the height Hm of the highest point on the ceramic substrate.

[0046] The pixel value of each pixel point in the background horizontal plane area is traversed. The pixel value represents the height value of the background horizontal plane position corresponding to the pixel point. The average height of the entire background horizontal plane is calculated, that is, the average height value H0 of the background horizontal plane is obtained.

[0047] The height difference △H of the warped surface relative to the reference surface is obtained by subtracting the thickness Tm at (Xm, Ym) from the height Hm at (Xm, Ym) and then subtracting the height H0 of the reference surface. △H = Hm - Tm - H0; The ratio of △H to the long side Height of the ceramic substrate is the warp of the ceramic substrate: Warp = △H / Height.

[0048] At this point, the warpage of the ceramic substrate has been measured using the above method. By turning the ceramic substrate over and repeating the above warpage measurement method, the warpage of the front side and the warpage of the back side of the ceramic substrate can be calculated.

[0049] Example 2: This embodiment provides a device for measuring the size, thickness, and warpage deformation of a ceramic substrate used for heat dissipation in a high-power power electronic module, comprising: A hollow fixture, wherein the middle portion is hollowed out to form a hollow groove and has a support surface for carrying the object to be measured, wherein the support surface is a horizontal surface; The upper laser displacement meter and the lower laser displacement meter are relatively arranged on the upper and lower sides of the hollow fixture. The upper laser displacement meter is used to measure the distance to the upper surface of the object placed on the hollow fixture, and the lower laser displacement meter is used to measure the distance to the lower surface of the object placed on the hollow fixture; Thickness calibration plate, which is a high-precision standard thickness calibration plate with a thickness of t, is used to calculate the installation distance Z between the upper laser displacement meter and the lower laser displacement meter; a 3D line laser measuring instrument configured to obtain a height image of a surface of a measured object; Motion platform, driving the objects on the hollow fixture to move horizontally; The first calculation module includes a first relational expression, a second relational expression, and a third relational expression. The first relational expression is configured to calculate the single-point installation spacing between the upper laser displacement meter and the lower laser displacement meter based on the sum of the distance d1 from the upper laser displacement meter to the upper surface of the thickness calibration plate placed in the hollow fixture, the distance d2 from the lower laser displacement meter to the lower surface of the thickness calibration plate, and the thickness t of the thickness calibration plate. The second relational expression is configured to calculate the installation spacing Z between the upper laser displacement meter and the lower laser displacement meter by taking the average of multiple single-point installation spacings. The third relational expression is configured to calculate the thickness value T of the ceramic substrate at the measurement point on the hollow fixture = Z - (D1 + D2) based on the installation spacing Z, the upper distance D1 measured by the upper laser displacement meter to the upper surface of the ceramic substrate at the measurement point, and the lower distance D2 measured by the lower laser displacement meter to the lower surface of the ceramic substrate at the measurement point. a first processing module configured to divide the height image into a ceramic substrate region and a background horizontal plane region; A second processing module is configured to rotate and straighten the ceramic substrate region to obtain RotateRegion; The second calculation module includes a fourth relationship, wherein the fourth relationship is configured to calculate the width of the ceramic substrate Width = Xpixel * Xaccuracy and the height Height = Ypixel * Yaccuracy based on the number of pixels occupied by the width Xpixel and the number of pixels occupied by the height Ypixel of the RotateRegion, and the pixel accuracy Xaccuracy in the X direction and the pixel accuracy Yaccuracy in the Y direction of the 3D line laser measuring instrument; The third processing module is configured to: traverse the pixel value of each pixel point in the ceramic substrate area, extract the highest area, and record the center point (Xm, Ym) of the highest area as the position of the highest point of the ceramic substrate, and the pixel value at (Xm, Ym) is the height value Hm of the highest point of the ceramic substrate; traverse the pixel value of each pixel point in the background horizontal plane area, calculate the height average of the entire background horizontal plane, and obtain the average height value H0 of the background horizontal plane; The third calculation module includes a fifth relationship, which is configured to calculate the warpage of the ceramic substrate Warp = (Hm - Tm - H0) / Height based on the height value Hm at the highest point (Xm, Ym) of the ceramic substrate, the thickness value Tm at the highest point (Xm, Ym) calculated by the first calculation module, and the average height H0 of the background horizontal plane area.

[0050] Example 3: This embodiment provides a device, comprising: memory for storing computer programs; The processor is used to execute a computer program to implement a method for measuring the size and warpage of a ceramic substrate for heat dissipation of a high-power electronic module. The method for measuring the size and warpage of a ceramic substrate for heat dissipation of a high-power electronic module is the same as the method steps described in Example 1.

[0051] Example 4: This embodiment provides a computer-readable storage medium, and a computer program stored on the computer-readable storage medium. When the computer program is executed by a processor, it implements the measurement of the size, thickness, and warpage deformation of a ceramic substrate used for heat dissipation of a high-power power electronic module. The steps for measuring the size, thickness, and warpage deformation of the ceramic substrate used for heat dissipation of a high-power power electronic module are the same as the method steps described in Example 1.

[0052] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for measuring the size and warpage of a ceramic substrate used for heat dissipation in a high-power electronic module, characterized in that: The following steps are involved: S1. Place the ceramic substrate on a horizontal surface and use a 3D line laser measuring instrument to scan the surface of the ceramic substrate to obtain a height image of the surface of the ceramic substrate; S2, dividing the height image into a ceramic substrate area and a background horizontal plane area; S3, rotating and straightening the ceramic substrate area and calculating the width of the ceramic substrate Width and height Height ; S4. Measure the position of the highest point of the ceramic substrate and the height value of the highest point according to the height image. Hm And the horizontal plane height value of the background horizontal plane area H0 , use the laser displacement meter to measure the thickness of the highest point of the ceramic substrate Tm , according to the height value of the highest point of the ceramic substrate Hm , thickness value Tm And the water level height value H0 Calculate the warpage of ceramic substrates Warp .

2. The method for measuring the size and warpage of a ceramic substrate for heat dissipation of a high-power electronic module according to claim 1, characterized in that: Step S2 includes the following steps: S21, using a Gaussian filter to smooth and remove noise from the height image; S22, calculating the gradient and direction of each pixel of the height image, and filtering each pixel to retain the pixel with the extreme gradient. The pixel position of the local extreme value is the edge candidate point; S23, setting a threshold, edge candidate points with absolute values ​​greater than the threshold are regarded as image edges, and image edge pixels are classified into strong edges, weak edges, and non-edges; S24, retain strong edge pixels and discard non-edge pixels; S25, analyzing the positional relationship between weak edges and strong edges, and performing secondary screening on weak edges; S26 , jointly processing the retained weak edge pixels and the strong edge pixels to form a complete edge contour line, thereby obtaining a ceramic substrate area, and the remaining area is a background horizontal plane area.

3. The method for measuring the size and warpage of a ceramic substrate for heat dissipation of a high-power electronic module according to claim 1, characterized in that: Step S3 includes the following steps: S31, record the ceramic substrate area as Region, calculate the row coordinates of the center point of Region Row, Column coordinates Column and the tilt angle of the circumscribed rectangle Phi ; S32, with ( Column , Row ) is the center of rotation, with - Phi Define an affine matrix for the rotation angle, and perform an affine transformation on Region to obtain the rotated and rectified ceramic substrate region, which is recorded as RotateRegion. S33. Calculate the size of RotateRegion to obtain the number of pixels occupied by the width of the ceramic substrate. Xpixel and the number of pixels occupied by the height Ypixel ; S34, according to Xpixel 、 Ypixel And the pixel accuracy of the 3D line laser measuring instrument in the X direction Xaccuracy and pixel accuracy in the Y direction Yaccuracy , calculate the width of the ceramic substrate Width and height Height : Width = Xpixel * Xaccuracy ； Height = Ypixel * Yaccuracy 。 4. The method for measuring the size and warpage of a ceramic substrate for heat dissipation of a high-power electronic module according to claim 1, characterized in that: Step S4 includes the following steps: S41, traversing the pixel value of each pixel point in the ceramic substrate area, the pixel value is the height value of the position on the ceramic substrate corresponding to the pixel point, and the position with the largest pixel value is the position with the highest warpage on the ceramic substrate; S42, using binarization to extract the highest pixel, and grouping the suspected pixels with the same height value range together as a suspected area; S43, using Blob analysis to extract and mark the connected domains of the suspected area, and each marked Blob represents a suspected target; S44. Screen the suspected targets based on width, height, and area features. The largest area that is retained is the highest area of ​​the ceramic substrate. The center point of the highest area ( Xm , Ym ) is the highest point of the ceramic substrate, ( Xm , Ym ) is the height of the highest point of the ceramic substrate Hm ; S45, traverse the pixel value of each pixel point in the background horizontal plane area, the pixel value is the height value of the background horizontal plane position corresponding to the pixel point, calculate the height average of the entire background horizontal plane, and obtain the horizontal plane height value of the background horizontal plane area H0 ; S46, using the laser displacement meter to measure ( Xm , Ym ) at the thickness value Tm ; S47. Calculate the warpage of ceramic substrates Warp = (Hm - Tm - H0） / Height .

5. The method for measuring the size and warpage of a ceramic substrate for heat dissipation of a high-power electronic module according to claim 1, characterized in that: The method for measuring thickness value with a through-beam laser displacement meter comprises the following steps: S461. Provide a hollow fixture and a thickness calibration plate. Set an upper laser displacement meter above the hollow fixture and a lower laser displacement meter below the hollow fixture. The thickness of the thickness calibration plate is t ; S462. Place the thickness calibration plate on the hollow fixture, randomly select several measurement points on the thickness calibration plate, and use the upper laser displacement meter to measure the distance to the upper surface of the thickness calibration plate for each measurement point on the thickness calibration plate. d1 , use the lower laser displacement meter to measure the distance to the lower surface of the thickness calibration plate d2 ; S463. For each measuring point on the thickness calibration plate, calculate the single-point installation distance between the upper laser displacement meter and the lower laser displacement meter. z = d1 + d2 + t , take the average value to get the installation distance between the upper laser displacement meter and the lower laser displacement meter Z ; S464, placing the ceramic substrate on the hollow fixture, and using the upper laser displacement meter to measure the upper distance to the upper surface of each measuring point on the ceramic substrate. D1 , use the lower laser displacement meter to measure the lower distance to the lower surface of the measuring point D2 ; S465, calculate the thickness value at each measuring point on the ceramic substrate T = Z - ( D1 + D2 ), take the average thickness value of all measuring points to get the average thickness value of the ceramic substrate.

6. The method for measuring the size and warpage of a ceramic substrate for heat dissipation of a high-power electronic module according to claim 1, characterized in that: The method further includes: step S5, measuring the thickness of the ceramic substrate using a through-beam laser displacement meter, including the following steps: S51. Provide a hollow jig and a thickness calibration plate, and set an upper laser displacement meter above the hollow jig and a lower laser displacement meter below the hollow jig; S52. Use the thickness calibration plate to calculate the installation distance between the upper laser displacement meter and the lower laser displacement meter Z ; S53, placing the ceramic substrate on the hollow fixture, and measuring the upper distance to the upper surface of each measuring point on the ceramic substrate using the upper laser displacement meter D1 , use the lower laser displacement meter to measure the lower distance to the lower surface of the measuring point D2 ; S54. Calculate the thickness value at each measuring point T = Z - ( D1 + D2 ), take the average thickness value of all measuring points to get the average thickness value of the ceramic substrate.

7. The method for measuring the size and warpage of a ceramic substrate for heat dissipation of a high-power electronic module according to claim 6, characterized in that: Step S52 includes the following steps: S521. Place the thickness calibration plate on the hollow fixture and use the upper laser displacement meter to measure the distance to the upper surface of the thickness calibration plate. d1 , use the lower laser displacement meter to measure the distance to the lower surface of the thickness calibration plate d2 ; S522, according to the thickness of the calibration plate t , the measured distance d1 and distance d2 , calculate the single point installation distance between the upper laser displacement meter and the lower laser displacement meter z = d1 + d2 + t ; S523. Randomly select several measuring points on the thickness calibration plate and repeat steps S521 to S522 to obtain several single-point installation spacings. z , take the average value to get the installation distance between the upper laser displacement meter and the lower laser displacement meter Z .

8. A device for measuring the size and warpage of a ceramic substrate used for heat dissipation in a high-power electronic module, characterized in that: It includes: Hollow jig; An upper laser displacement meter and a lower laser displacement meter are arranged on the upper and lower sides of the hollow fixture relative to each other; The upper laser displacement meter is configured to measure the distance to the upper surface of the object placed on the hollow jig, and the lower laser displacement meter is configured to measure the distance to the lower surface of the object placed on the hollow jig; A thickness calibration plate, with a thickness of t, is configured to assist in calculating the installation spacing between the upper laser displacement meter and the lower laser displacement meter. Z ; a 3D line laser measuring instrument configured to obtain a height image of a surface of a measured object; The first calculation module includes a first relational expression, a second relational expression, and a third relational expression; the first relational expression is configured as follows: the distance from the upper laser displacement meter to the upper surface of the thickness calibration plate placed in the hollow fixture is d1 , the distance from the lower laser displacement meter to the lower surface of the thickness calibration plate d2 And the thickness of the thickness calibration plate t , the sum of the three is calculated to obtain the single-point installation distance between the upper laser displacement meter and the lower laser displacement meter; the second relationship is configured as: according to multiple single-point installation distances, the average of them is calculated to obtain the installation distance between the upper laser displacement meter and the lower laser displacement meter Z The third relationship is configured as follows: according to the installation spacing Z, the upper distance measured by the laser displacement meter to the upper surface of the ceramic substrate measuring point on the hollow fixture D1 And the lower distance measured by the laser displacement meter to the lower surface of the ceramic substrate measurement point D2 , calculate the thickness value of the ceramic substrate at the measurement point T = Z -( D1 + D2 ); a first processing module configured to divide the height image into a ceramic substrate region and a background horizontal plane region; A second processing module is configured to rotate and straighten the ceramic substrate region to obtain a rotated and straightened ceramic substrate region, which is recorded as RotateRegion; The second calculation module includes a fourth relationship, which is configured as follows: according to the number of pixels occupied by the width of RotateRegion Xpixel and the number of pixels occupied by the height Ypixel , and the pixel accuracy of the 3D line laser measuring instrument in the X direction Xaccuracy and pixel accuracy in the Y direction Yaccuracy, Calculate the width of the ceramic substrate Width = Xpixel * Xaccuracy, high Height = Ypixel * Yaccuracy ; The third processing module is configured to: traverse the pixel value of each pixel point in the ceramic substrate area, extract the highest area, and record the center point of the highest area ( Xm , Ym ) is the highest point of the ceramic substrate, ( Xm , Ym ) is the height of the highest point of the ceramic substrate Hm ; Traverse the pixel value of each pixel point in the background horizontal plane area, calculate the height average of the entire background horizontal plane, and obtain the average height value of the background horizontal plane H0 ; The third calculation module includes a fifth relational expression, wherein the fifth relational expression is configured as follows: according to the highest point of the ceramic substrate ( Xm , Ym ) Hm , the highest point calculated by the first calculation module ( Xm , Ym ) at the thickness value Tm, and the average height of the background horizontal area H0 , calculate the warpage of the ceramic substrate Warp = (Hm - Tm - H0） / Height .

9. A device for measuring the size and warpage of ceramic substrates used for heat dissipation of high-power electronic modules, characterized in that: It includes: Memory for storing computer programs; A processor is configured to execute the computer program to implement the method for measuring the size and warpage of a ceramic substrate for heat dissipation of a high-power power electronic module according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that The computer program stored on the computer-readable storage medium, when executed by a processor, implements the method for measuring the size and warpage of a ceramic substrate for heat dissipation of a high-power power electronic module according to any one of claims 1 to 7.

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