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

Abstract

This invention relates to a method, apparatus, device, and medium for measuring the dimensions and warpage of a ceramic substrate used for heat dissipation in high-power power electronic modules. The method includes the following steps: S1, placing the ceramic substrate on a horizontal surface and scanning the surface of the ceramic substrate using a 3D line laser measuring instrument to obtain a height image of the ceramic substrate surface; S2, dividing the height image into a ceramic substrate area and a background horizontal surface area; S3, rotating and aligning the ceramic substrate area and calculating the width and height of the ceramic substrate; S4, based on the height image, measuring the position of the highest point of the ceramic substrate, the height value at the highest point, and the horizontal surface height value of the background horizontal surface area; measuring the thickness value at the highest point of the ceramic substrate using a through-beam laser displacement meter; and calculating the warpage of the ceramic substrate based on the height value, thickness value, and horizontal surface height value at the highest point. This invention can accurately measure the warpage, dimensions, and thickness of ceramic substrates, ensuring product performance.

Description

Technical Field

[0001] This invention relates to the field of precision measurement technology, specifically to a method, apparatus, equipment, and medium for measuring the dimensions and warpage of a ceramic substrate used for heat dissipation in high-power power electronic modules. Background Technology

[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, high-power environments for extended periods, their heat dissipation performance is crucial to their stability and reliability. If heat cannot be dissipated in time, it can easily lead to bond wire peeling or melting, resulting in module failure. Therefore, the requirements for the heat dissipation performance of power electronic modules are becoming increasingly stringent. The current carrying capacity and heat dissipation of high-power power electronic modules mainly rely on the ceramic copper-clad substrate within the module. This substrate is composed of a composite material with a "copper-ceramic-copper" structure. The ceramic substrate not only possesses excellent properties such as high heat dissipation, high insulation, and high mechanical strength, but also has a thermal expansion coefficient that matches the chip well. Simultaneously, it combines the high current carrying capacity and high thermal conductivity of oxygen-free copper, making it a key packaging material for power electronic modules.

[0003] Ceramic substrates exhibit ultra-high flexural strength and fracture toughness in mechanical properties, and ultra-high thermal conductivity, low coefficient of thermal expansion, low dielectric constant, and high resistance to electrical penetration in physical properties. They also demonstrate good solderability and a coefficient of thermal expansion similar to semiconductor materials, facilitating integration with chips. However, key parameters such as the dimensions, thickness, and warpage of the ceramic substrate significantly impact the performance of the packaged power electronic module. When the dimensions and thickness of the ceramic substrate deviate from standard process requirements, or when warpage occurs due to stress during processing or use, significant stress is generated at the copper-ceramic interface, leading to ceramic cracking or copper layer peeling, ultimately causing the entire power electronic module to fail. Therefore, accurate measurement of the dimensions, thickness, and warpage of the ceramic substrate is crucial.

[0004] Currently, the dimensions, thickness, and warpage of ceramic substrates are primarily measured manually. However, manual measurement suffers from poor accuracy and low efficiency, failing to meet the high precision and efficiency demands of modern industry. Furthermore, manual measurement is susceptible to operator subjectivity, potentially leading to inconsistent results and increasing the risk of defective products. To address these issues, the industry is increasingly focusing on building high-precision automated measurement systems using precision measuring instruments combined with image processing technology to automatically measure the dimensions, thickness, and warpage deformation of ceramic substrates. This method not only significantly improves measurement accuracy but also effectively reduces the outflow of defective products, eliminates human error, and minimizes the waste of human resources, thereby saving on operating costs and improving customer satisfaction.

[0005] However, some technical challenges remain to be addressed in existing technologies. For example, how to accurately extract ceramic substrate regions from complex backgrounds using efficient image processing techniques, how to eliminate the influence of ceramic substrate tilt on dimensional measurement results during the measurement process, and how to accurately calculate the warpage of the ceramic substrate by integrating multiple measurement data. To address these issues, this invention proposes a high-precision automated measurement method based on precision measuring instruments and image processing technology, aiming to overcome the shortcomings of existing technologies and provide reliable technical support for the quality control of ceramic substrates. Summary of the Invention

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

[0007] This invention achieves the above objective through the following technical solution: a method for measuring the dimensions and warpage of a ceramic substrate for heat dissipation in high-power power electronic modules, comprising the following steps:

[0008] 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 ceramic substrate surface.

[0009] S2. Divide the height image into the ceramic substrate area and the background horizontal plane area;

[0010] S3. After rotating and aligning the ceramic substrate area, calculate the width of the ceramic substrate. Width and height Height ;

[0011] S4. Based on the height image, measure the position of the highest point of the ceramic substrate and the height value at the highest point. Hm and the horizontal height value of the background horizontal plane area. H0 The thickness at the highest point of the ceramic substrate was measured using a through-beam laser displacement meter. Tm Based on the height value at the highest point of the ceramic substrate Hm Thickness value Tm and horizontal height value H0 Calculate the warpage of the ceramic substrate Warp .

[0012] Furthermore, step S2 includes the following steps:

[0013] S21. Smooth and denoise the height image using a Gaussian filter;

[0014] S22. Calculate the gradient and direction of each pixel in the height image, and filter each pixel to retain the pixels with extreme gradient values. The pixel positions of local extreme values ​​are edge candidate points.

[0015] S23. Set a threshold. Edge candidate points with an absolute value greater than the threshold are considered as image edges. Divide image edge pixels into strong edges, weak edges, and non-edges.

[0016] S24. Retain strong edge pixels and discard non-edge pixels;

[0017] S25. Analyze the positional relationship between weak edges and strong edges, and perform secondary screening on weak edges;

[0018] S26. The retained weak edge pixels are processed together with the strong edge pixels to form a complete edge outline, thus obtaining the ceramic substrate area. The remaining area is the background horizontal plane area.

[0019] Furthermore, step S3 includes the following steps:

[0020] S31. Let the ceramic substrate region be Region, and calculate the row coordinates of the center point of Region. Row、 Column coordinates Column and the slant angle of the circumscribed rectangle Phi ;

[0021] S32, with ( Column , Row ) as the center of rotation, with - Phi Define an affine matrix for the rotation angle, and after performing an affine transformation on the Region, obtain the rotated and aligned ceramic substrate region, denoted as RotateRegion;

[0022] 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 height Ypixel ;

[0023] S34, according to Xpixel , Ypixel And the pixel accuracy of the 3D line laser measuring instrument in the X direction. Xaccuracy and pixel precision in the Y direction Yaccuracy The width of the ceramic substrate was calculated. Width and height Height :

[0024] Width = Xpixel * Xaccuracy ;

[0025] Height = Ypixel * Yaccuracy .

[0026] Furthermore, step S4 includes the following steps:

[0027] S41. Traverse the pixel value of each pixel in the ceramic substrate area. The pixel value is the height value of the ceramic substrate position corresponding to the pixel. The position with the largest pixel value is the position with the highest warping on the ceramic substrate.

[0028] S42. Use binarization to extract the highest pixel, and group together suspected pixels with the same height value range as suspected areas;

[0029] S43. Use Blob analysis to extract and label the connected components of suspected regions. Each labeled Blob represents a suspected target.

[0030] S44. Based on the width, height, and area characteristics, suspected targets are screened, and the largest area that is ultimately retained is the highest area of ​​the ceramic substrate, and the center point of the highest area ( Xm , Ym () represents the position of the highest point on the ceramic substrate. Xm , Ym The pixel value at () is the height of the highest point on the ceramic substrate. Hm ;

[0031] S45. Traverse the pixel value of each pixel within the background horizontal plane region. The pixel value is the height value of the background horizontal plane position corresponding to that pixel. Calculate the average height of the entire background horizontal plane to obtain the horizontal plane height value of the background horizontal plane region. H0 ;

[0032] S46. Using a through-beam laser displacement meter to measure ( Xm , Ym Thickness value at ) Tm ;

[0033] S47. Calculate the warpage of the ceramic substrate. Warp = (Hm - Tm - H0） / Height .

[0034] Furthermore, the method for measuring thickness values ​​using a through-beam laser displacement meter includes the following steps:

[0035] S461. A cutout fixture and a thickness calibration plate are provided. An upper laser displacement meter is installed above the cutout fixture, and a lower laser displacement meter is installed below it. The thickness of the thickness calibration plate is... t ;

[0036] S462. Place the thickness calibration plate on the hollow jig. Randomly select several measurement points on the thickness calibration plate. For each measurement point on the thickness calibration plate, use an upper laser displacement gauge to measure the distance to the upper surface of the thickness calibration plate. d1 The distance to the lower surface of the thickness calibration plate was measured using a lower laser displacement meter. d2 ;

[0037] S463. For each measurement point on the thickness calibration plate, calculate the single-point installation distance between the upper and lower laser displacement gauges. z = d1 + d2 + t The average value is used to obtain the installation distance between the upper and lower laser displacement gauges. Z ;

[0038] S464. Place the ceramic substrate on the hollowed-out fixture, and for each measuring point on the ceramic substrate, use an upper laser displacement meter to measure the distance from the upper surface of the measuring point to the upper surface of the measuring point. D1 The lower distance of the measuring point on the lower surface was measured using a lower laser displacement meter. D2 ;

[0039] S465. Calculate the thickness value at each measurement point on the ceramic substrate. T = Z - ( D1 + D2 The average thickness of the ceramic substrate is obtained by taking the average of the thickness values ​​at all measurement points.

[0040] Furthermore, it also includes: step S5, measuring the thickness of the ceramic substrate using a through-beam laser displacement meter, including the following steps:

[0041] S51. Provide a cutout fixture and a thickness calibration plate, with an upper laser displacement meter installed above the cutout fixture and a lower laser displacement meter installed below it;

[0042] S52. Calculate the installation distance between the upper and lower laser displacement gauges using a thickness calibration plate. Z ;

[0043] S53. Place the ceramic substrate on the hollowed-out fixture, and for each measuring point on the ceramic substrate, use an upper laser displacement meter to measure the distance from the upper surface of the measuring point to the upper surface of the measuring point. D1 The lower distance of the measuring point on the lower surface was measured using a lower laser displacement meter. D2 ;

[0044] S54. Calculate the thickness value at each measurement point. T = Z - ( D1 +D2 The average thickness of the ceramic substrate is obtained by taking the average of the thickness values ​​at all measurement points.

[0045] Furthermore, step S52 includes the following steps:

[0046] S521. Place the thickness calibration plate on the hollow jig and use the upper laser displacement gauge to measure the distance to the upper surface of the thickness calibration plate. d1 The distance to the lower surface of the thickness calibration plate was measured using a lower laser displacement meter. d2 ;

[0047] S522, Based on the thickness of the calibration plate t Measured distance d1 and distance d2 The single-point installation distance between the upper and lower laser displacement gauges was calculated. z = d1 + d2 + t ;

[0048] S523. Randomly select several measurement points on the thickness calibration plate, and repeat steps S521 to S522 to obtain several single-point installation spacings. z The average value is used to obtain the installation distance between the upper and lower laser displacement gauges. Z .

[0049] Another object of the present invention is to provide a device for measuring the size and warpage of a ceramic substrate for heat dissipation of a high-power power electronic module, comprising:

[0050] Hollow jig;

[0051] An upper laser displacement meter and a lower laser displacement meter are disposed opposite to each other on the upper and lower sides of the hollowing fixture; the upper laser displacement meter is configured to measure the distance to the upper surface of an object placed on the hollowing fixture, and the lower laser displacement meter is configured to measure the distance to the lower surface of an object placed on the hollowing fixture.

[0052] A thickness calibration plate, with a thickness of t, is configured to assist in calculating the installation distance between the upper laser displacement gauge and the lower laser displacement gauge. Z ;

[0053] A 3D line laser measuring instrument is configured to acquire a height image of the surface of the object being measured;

[0054] The first calculation module includes a first relation, a second relation, and a third relation; the first relation is configured as follows: based on the distance measured by the upper laser displacement gauge to the upper surface of the thickness calibration plate placed in the hollow fixture. d1 The distance measured by the laser displacement gauge to the lower surface of the thickness calibration plate.d2 And the thickness of the thickness calibration plate t The summation of these three factors yields the single-point installation spacing between the upper and lower laser displacement gauges. The second formula is configured as follows: based on multiple single-point installation spacings, the average of these spacings is used to calculate the installation spacing between the upper and lower laser displacement gauges. Z The third relation is configured as follows: based on the installation spacing Z, the upper distance measured by the upper laser displacement gauge to the upper surface of the measuring point on the ceramic substrate of the hollow fixture. D1 And the lower distance measured by the lower laser displacement meter to the lower surface of the measuring point on the ceramic substrate. D2 The thickness value of the ceramic substrate at that measurement point was calculated. T = Z -( D1 + D2 );

[0055] The first processing module is configured to divide the height image into a ceramic substrate region and a background horizontal plane region.

[0056] The second processing module is configured to rotate and straighten the ceramic substrate region to obtain the rotated and straightened ceramic substrate region, denoted as RotateRegion.

[0057] The second calculation module includes a fourth relation, which is configured to: calculate based on the number of pixels occupied by the width of the RotateRegion. Xpixel and the number of pixels occupied by height Ypixel And the pixel accuracy in the X direction of the 3D line laser measuring instrument. Xaccuracy and pixel precision in the Y direction Yaccuracy, The width of the ceramic substrate was calculated. Width = Xpixel * Xaccuracy, high Height = Ypixel * Yaccuracy ;

[0058] The third processing module is configured to: traverse the pixel values ​​of each pixel within the ceramic substrate region, extract the highest value region, and record the center point of the highest value region. Xm , Ym ) represents the location of the highest point on the ceramic substrate. Xm , Ym The pixel value at () is the height of the highest point on the ceramic substrate. Hm ; Traverse the pixel values ​​of each pixel within the background horizontal plane region, calculate the average height of the entire background horizontal plane, and obtain the average height value of the background horizontal plane. H0 ;

[0059] The third calculation module includes a fifth relation, which is configured to: based on the highest point of the ceramic substrate ( Xm , Ym Height value at ) Hm The highest point calculated using the first calculation module ( Xm , Ym Thickness value at ) Tm、 and the average height value of the background horizontal plane area H0 The warpage of the ceramic substrate was calculated. Warp = (Hm - Tm - H0） / Height .

[0060] Another object of the present invention is to provide a device for measuring the size and warpage of a ceramic substrate for heat dissipation of a high-power power electronic module, comprising:

[0061] Memory, used to store computer programs;

[0062] A processor is used to execute the computer program to implement the method for measuring the size and warpage of the ceramic substrate for heat dissipation of high-power power electronic modules as described above.

[0063] Another object of the present invention is to provide a computer-readable storage medium on which a computer program is stored, which, 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 as described above.

[0064] This invention uses a standard thickness calibration plate to calculate the installation spacing of a through-beam laser displacement meter; it uses the laser displacement meter to measure the thickness of a ceramic substrate; it 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; it uses image enhancement and edge extraction techniques to divide the image area into a ceramic substrate area and a background horizontal plane area; based on the tilt angle of the ceramic substrate, it uses affine transformation to rotate and straighten the ceramic substrate area to prevent the tilt of the ceramic substrate from affecting the accuracy of the dimensional measurement results; it calculates the width and height of the straightened ceramic substrate; based on the height image of the ceramic substrate, it measures the position and height value of the highest point of the ceramic substrate, and uses the through-beam laser displacement meter to measure the thickness value at the highest point of the ceramic substrate; it calculates the warpage of the ceramic substrate based on the thickness value, height value, and horizontal plane height value at the highest point of the ceramic substrate.

[0065] Compared with existing technologies, the beneficial effects of this invention—a method, apparatus, equipment, and medium for measuring the dimensions and warpage of a ceramic substrate for heat dissipation in high-power power electronic modules—are as follows: By using precision measuring instruments combined with image processing technology to construct 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. Then, a 3D line laser measuring instrument is used to measure the dimensions of the ceramic substrate and its height difference from the horizontal plane. The warpage of the ceramic substrate is calculated by combining the height difference between the ceramic substrate and the horizontal plane with the thickness of the ceramic substrate itself. This method improves measurement accuracy compared to methods using a single measuring instrument to measure thickness or warpage. The automated measurement technology reduces defective products compared to manual measurement, eliminates interference from human factors, reduces waste of human resources, and effectively improves customer satisfaction while saving on enterprise operating costs. Specifically:

[0066] (1) High-precision thickness measurement was achieved: using upper and lower through-beam laser displacement gauges, along with a thickness calibration plate, the installation distance between the upper and lower through-beam laser displacement gauges was calculated. Z Furthermore, the thickness of the ceramic substrate is calculated by utilizing the mounting spacing between the upper and lower laser displacement gauges. T And use the difference method ( T = Z - ( D1 + D2 Eliminates systematic errors; thickness measurement resolution reaches the micrometer level, resulting in high detection accuracy;

[0067] (2) Precise segmentation of ceramic substrate area improves the accuracy of ceramic substrate size detection: Combined with 3D line laser triangulation to generate height image, Gaussian filtering for noise reduction and Canny edge detection to extract substrate outline, effectively distinguishing ceramic substrate area from background horizontal area, edge positioning accuracy reaches ±5μm, overcoming the misjudgment problem caused by the close height of substrate and background in traditional visual method;

[0068] (3) Tilt correction is used for size calculation: The ceramic substrate area is automatically rotated and aligned based on affine transformation, and the actual size of the ceramic substrate is calculated by combining pixel accuracy conversion. This eliminates the influence of substrate placement tilt on size measurement. Width / height measurement error ≤0.02%, which is suitable for rectangular / irregular substrates of different specifications.

[0069] (4) Dynamic assessment of warpage: Under the premise of accurately segmenting the ceramic substrate area, the highest point of the ceramic substrate area is located by Blob analysis, and the thickness value of the highest point is obtained by linking with the laser displacement meter. Combined with the average height of the reference horizontal plane, the relative warpage is calculated. △H = Hm - Tm - H0 ) and warpage (Warp = △H / Height This enables fully automated quantitative evaluation of warpage with a detection sensitivity of 0.001 mm / m, providing data support for optimizing the heat dissipation performance of IGBT modules. Attached Figure Description

[0070] Figure 1 This is a schematic diagram of the steps in an embodiment of the present invention;

[0071] Figure 2 This is a schematic diagram illustrating the principle of laser displacement measurement in an embodiment of the present invention;

[0072] Figure 3 This is a schematic diagram illustrating the principle of the 3D line laser measuring instrument in an embodiment of the present invention;

[0073] Figure 4 This is a schematic diagram of the steps in an embodiment of the present invention to divide a height image into a ceramic substrate region and a background horizontal plane region;

[0074] Figure 5 This is a schematic diagram of the steps for calculating the width and height of the ceramic substrate after rotation and alignment in an embodiment of the present invention;

[0075] Figure 6 This is a schematic flowchart illustrating the steps of calculating the warpage of the ceramic substrate based on the height image in an embodiment of the present invention.

[0076] Figure 7 This is a schematic flowchart of the method for measuring thickness values ​​using a through-beam laser displacement meter in an embodiment of the present invention. Detailed Implementation

[0077] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a method for measuring the dimensions and warpage of a ceramic substrate for heat dissipation of a high-power power electronic module according to the present invention. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0078] Unless otherwise defined, 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 pertains.

[0079] Example 1:

[0080] The following description, in conjunction with the accompanying drawings, details a specific scheme for measuring the dimensions and warpage of a ceramic substrate for heat dissipation in a high-power power electronic module provided by the present invention.

[0081] Please see Figures 1 - 7 The diagram illustrates a flowchart of a method for measuring the dimensions and warpage of a ceramic substrate for heat dissipation in a high-power power electronic module according to an embodiment of the present invention. The method includes the following steps:

[0082] Step S001: Install the upper and lower through-beam laser displacement gauges, and calculate the installation spacing of the through-beam laser displacement gauges using a standard thickness calibration plate. Z The thickness of the ceramic substrate was measured using a through-beam laser displacement meter. T .

[0083] In semiconductor manufacturing technology, ceramic substrates primarily serve as carriers for chips in various power electronic devices. A copper-clad ceramic substrate is formed on both sides, creating a "copper-ceramic-copper" composite material. In IGBT module packaging, a copper-clad ceramic substrate with IGBT chips soldered onto the module base plate, forming a heat dissipation channel for the IGBT chips. The ceramic substrate absorbs the heat generated by the chip and conducts it to the heat sink, achieving heat exchange between the chip and the external environment to dissipate heat.

[0084] In this embodiment, upper and lower through-beam laser displacement gauges are installed, and the installation spacing of the through-beam laser displacement gauges is calculated using a standard thickness calibration plate. Z The thickness of the ceramic substrate was measured using a through-beam laser displacement meter. T Specifically, it includes:

[0085] Two laser displacement gauges are installed above and below the hollowing fixture, with their laser axes perpendicular to the horizontal plane of the fixture. The lasers in the displacement gauges emit a beam with a broad spectrum. λ1 - λn Polychromatic light, when incident, is decomposed into monochromatic light of different wavelengths by a dispersive objective lens. Because of their different refractive indices, these different wavelengths of light are focused at different positions along the optical axis, forming a continuous spectral distribution. Wavelength λi The axial distance between a single pixel and the lens is d(λi). Ideally, the wavelength and displacement satisfy the following relationship:

[0086] d ( λi )= m + kλi ;

[0087] in, k It is a proportionality constant, representing the axial distance d(λi) as a function of wavelength. λi The rate of change mThis is a constant term, representing the theoretical axial distance between a single pixel and the lens when λi=0. 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 is detected and analyzed by a spectrometer after passing through a pinhole filter. The pinhole filter filters out most of the spectral flux from the defocused reflection, ensuring that only light perfectly focused on the surface of the object passes through. The internal spectrometer interprets the wavelength of the received reflected light and determines its center wavelength, thus calculating the distance between the surface of the object being measured and the laser displacement meter. D This enables the distance measurement function, and its principle is as follows: Figure 2 As shown.

[0088] Place the standard thickness calibration plate on the hollow jig, and measure the distance from the upper laser displacement gauge to the upper surface of the calibration plate. d1 Distance from the lower laser displacement gauge to the lower surface of the calibration plate d2 and the thickness of the calibration plate t The sum of these three factors is the installation spacing between the upper and lower laser displacement gauges. Z，

[0089] Z = d1 + d2 + t；

[0090] Randomly select several measurement points on the calibration plate, repeat the above steps, and calculate multiple times, taking the average value to obtain the installation distance between the upper and lower laser displacement gauges. Z， Avoid error interference.

[0091] Place the ceramic substrate on the cutout fixture, select a thickness measurement point, and measure the distance from the upper laser displacement gauge to the upper surface of that point. D1 And the distance from the lower laser displacement meter to the lower surface of that point. D2 Based on the installation spacing of the upper and lower laser displacement gauges Z and the measured upper distance D1 and lower distance D2 The thickness of the ceramic substrate at that point can be calculated:

[0092] T = Z - ( D1 + D2 ).

[0093] According to the requirements for measuring the thickness of ceramic substrates, the thickness values ​​are measured at all measurement points, and then the average value is taken to obtain the thickness of the ceramic substrate. T .

[0094] Thus, the thickness of the ceramic substrate has been measured through the above steps. T This step can also be used to measure the thickness value at any point on the ceramic substrate.

[0095] Step S002: Use a 3D line laser measuring instrument to scan the surface of the object under test (in this embodiment, the object under test is the ceramic substrate to be tested), obtain a height image of the ceramic substrate surface, and use image enhancement and edge extraction techniques to divide the image area into the ceramic substrate area and the background horizontal plane area. Specifically:

[0096] The scanning field of a 3D line laser measuring instrument is generally larger than the actual size of the object being measured. Therefore, the height image obtained includes not only the ceramic substrate area, but also the background horizontal plane and other noise interference.

[0097] A ceramic substrate is placed on a horizontal surface. The laser in the 3D line laser measuring instrument emits a line laser beam that perpendicularly illuminates the surface of the object being measured, with the axis of the incident light coinciding with the normal direction of the object's plane. The incident light undergoes diffuse reflection on the object's surface, forming a laser spot. The imaging lens inside the 3D line laser measuring instrument converges and collects the reflected light, ultimately forming an image spot on the internal image sensor. The object is moved horizontally at a constant speed. When the surface of the object experiences undulations, the measured plane shifts along the laser axis. Simultaneously, the position of the image spot on the image sensor also shifts, and the displacement of the measured plane and the displacement of the image spot are in a one-to-one mapping relationship, the principle of which is as follows: Figure 3 As shown.

[0098] Specifically, make a pass through point A. L A perpendicular line is drawn from point B, with the foot of the perpendicular at point B; a line is drawn through point B. l The perpendicular line to the extension line, with the foot of the perpendicular at... Among them, △AOB and △ resemblance.

[0099] According to the principle of similar triangles, we can conclude that...

[0100] ;

[0101] According to the principles of trigonometric functions, we can conclude that...

[0102] ;

[0103] ;

[0104] ;

[0105] ;

[0106] Based on the above relationships, we can conclude that

[0107] ;

[0108] After simplification, the mapping relationship between the displacement of the measured plane and the displacement of the imaging spot is as follows:

[0109] ,

[0110] in L , l , α , β It is a constant, and its specific value is determined by the selection of the 3D line laser measuring instrument.

[0111] After scanning the entire surface of the object being measured, the actual displacement distance between each position on the surface of the object and the reference plane can be calculated by the displacement distance of the imaging spot, thereby generating a height image of the surface of the object being measured.

[0112] Because the ceramic substrate is relatively thin, its height is close to that of the horizontal plane when placed on the background. The height information of the ceramic substrate surface and the horizontal plane in the height 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 to make the edge between the ceramic substrate and the horizontal plane clearer and easier to extract.

[0113] A Gaussian frequency domain filter with specific specifications and resolution is generated based on the size of the original height image Image. The Gaussian filter is then used to perform a convolution operation on the height image Image. Specifically, the filter scans each pixel on the image and replaces the original value of the pixel with the weighted average of the values ​​of all pixels in the surrounding neighborhood of the scanned pixel and the filter. The Gaussian filter can smooth and denoise the image, effectively reducing the interference of background noise.

[0114] Specifically, generate a 3x3 horizontal convolution kernel. Gx and a 3x3 vertical convolution kernel Gy The image is convolved to calculate the gradients in the horizontal and vertical directions. The overall strength and direction of the edge can be calculated based on the gradient. Each pixel is filtered and selected, and the pixels with extreme gradient values ​​are retained. The pixel positions with local extreme values ​​are the edge candidate points.

[0115] A threshold is set, and edge candidate points with an absolute value greater than the given threshold are considered image edges. Edge pixels are divided into true edges (i.e., strong edges), suspected edges (i.e., 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 further filtered. The retained weak edge pixels are then jointly processed with strong edge pixels to form a complete edge contour. The area enclosed by the edge contour is the ceramic substrate area, and the remaining area is the background horizontal plane area.

[0116] Thus, the height image of the ceramic substrate surface was obtained using the above method, and the image area was divided into the ceramic substrate area and the background horizontal plane area.

[0117] Step S003: Based on the tilt angle of the ceramic substrate, use affine transformation to rotate and align the ceramic substrate area to prevent the tilt of the ceramic substrate from affecting the accuracy of the dimensional measurement results. Calculate the width of the aligned ceramic substrate. Width and height Height Specifically:

[0118] The ceramic substrate is generally rectangular in shape. Calculate the row coordinates of the center point of the region on the ceramic substrate. Row Column coordinates Column and the slant angle of the circumscribed rectangle. Phi .by( Column , Row ) as the center of rotation, with - Phi Define an affine matrix for the rotation angle, and perform an affine transformation on the Region to obtain the RotateRegion after rotation and alignment.

[0119] Specifically, each point on the image ( x , y ), around the center of rotation ( Column , Row Rotation angle - Phi Then, a new point is obtained ( x’ , y’ ),

[0120] x’ = Row + ( x - Row ) * cos(- Phi ) - ( y - Column ) * sin(- Phi );

[0121] y’ = Column + ( x- Row ) * sin(- Phi ) + ( y - Column ) * cos(- Phi );

[0122] Affine transformation is used to rotate and align the Region to obtain the RotateRegion, preventing the tilt of the ceramic substrate from affecting the accuracy of dimensional measurement results.

[0123] Calculate the size of the RotateRegion to obtain the number of pixels occupied by the width and height of the ceramic substrate, respectively. Xpixel and Ypixel, according to Xpixel and Ypixel And the pixel accuracy of the 3D line laser measuring instrument in the X and Y directions. Xaccuracy and Yaccuracy The width of the ceramic substrate was calculated. Width and height Height :

[0124] Width = Xpixel * Xaccuracy;

[0125] Height = Ypixel * Yaccuracy。

[0126] Thus, the width of the ceramic substrate was measured using the method described above. Width and height Height .

[0127] Step S004: Based on the ceramic substrate height image, measure the position and height of the highest point of the ceramic substrate. Use a through-beam laser displacement meter to measure the thickness at the highest point of the ceramic substrate. Calculate the warpage of the ceramic substrate based on the height, thickness, and horizontal height at the highest point. Warp Specifically:

[0128] Traverse the pixel value of each pixel within the ceramic substrate area. The pixel value represents the height value of the corresponding position on the ceramic substrate. The position with the largest pixel value is the position with the highest warping on the ceramic substrate.

[0129] The highest pixel is extracted using binarization, and suspected pixels with the same height value range are grouped together as suspected regions. Blob analysis is used to extract and label the connected components of the suspected regions. Each labeled blob represents a suspected target. Suspected targets are filtered based on features such as width, height, and area. The largest area that is ultimately retained is the highest region of the ceramic substrate, and the center point of the highest region (…)Xm , Ym This refers to the location of the highest point on the ceramic substrate. Xm , Ym The pixel value at point () represents the height of the highest point on the ceramic substrate. Hm .

[0130] Iterate through the pixel values ​​of each pixel within the background horizontal plane region. Each pixel value represents the height value of the corresponding position on the background horizontal plane. Calculate the average height of the entire background horizontal plane to obtain the average height value. H0 .

[0131] ( Xm , Ym Height value at ) Hm minus( Xm , Ym Thickness value at ) Tm Subtract the height value of the reference plane. H0 Obtain the height difference between the warped surface and the reference surface. △H ,

[0132] △H = Hm - Tm - H0 ;

[0133] △H With the long side of the ceramic substrate Height The ratio is the warpage of the ceramic substrate. Warp :

[0134] Warp = △H / Height .

[0135] Thus, the warpage of the ceramic substrate was measured using the method described above. Warp By flipping the ceramic substrate over and repeating the above warp measurement method, the warp of the front and back sides of the ceramic substrate can be calculated.

[0136] Example 2:

[0137] This embodiment provides a device for measuring the size, thickness, and warpage deformation of a ceramic substrate used for heat dissipation in high-power power electronic modules, comprising:

[0138] A hollowed-out fixture, wherein the middle part is hollowed out to form a hollowed-out groove, and has a supporting surface for supporting the object to be measured, wherein the supporting surface is a horizontal plane;

[0139] The upper laser displacement meter and the lower laser displacement meter are set opposite to each other on the upper and lower sides of the hollowing fixture. The upper laser displacement meter is used to measure the distance to the upper surface of the object placed on the hollowing fixture, and the lower laser displacement meter is used to measure the distance to the lower surface of the object placed on the hollowing fixture.

[0140] The thickness calibration plate is a high-precision standard thickness calibration plate with a thickness of t, used to calculate the installation distance Z between the upper and lower laser displacement gauges.

[0141] A 3D line laser measuring instrument is configured to acquire a height image of the surface of the object being measured;

[0142] A motion platform drives the object on the hollowed-out fixture to move horizontally.

[0143] The first calculation module includes a first relation, a second relation, and a third relation; the first relation is configured to: calculate the distance from the upper laser displacement meter to the upper surface of the thickness calibration plate placed in the hollow fixture. d1 Distance from the lower laser displacement gauge to the lower surface of the thickness calibration plate d2 And the thickness of the thickness calibration plate t The summation of these three factors yields the single-point installation spacing between the upper and lower laser displacement gauges. The second formula is configured as follows: based on multiple single-point installation spacings, the average of these spacings is used to calculate the installation spacing between the upper and lower laser displacement gauges. Z The third relation is configured as follows: based on the installation spacing Z, the upper distance measured by the upper laser displacement gauge to the upper surface of the measuring point on the ceramic substrate of the hollow fixture. D1 And the lower distance measured by the lower laser displacement meter to the lower surface of the measuring point on the ceramic substrate. D2 The thickness value of the ceramic substrate at that measurement point was calculated. T = Z -( D1 + D2 ) ;

[0144] The first processing module is configured to divide the height image into a ceramic substrate region and a background horizontal plane region.

[0145] The second processing module is configured to rotate and straighten the ceramic substrate region to obtain the RotateRegion;

[0146] The second calculation module includes a fourth relation, which is configured to: calculate based on the number of pixels occupied by the width of the RotateRegion. Xpixel and the number of pixels occupied by height Ypixel And the pixel accuracy in the X direction of the 3D line laser measuring instrument. Xaccuracy and pixel precision in the Y direction Yaccuracy, The width of the ceramic substrate was calculated.Width = Xpixel * Xaccuracy, high Height = Ypixel * Yaccuracy ;

[0147] The third processing module is configured to: traverse the pixel values ​​of each pixel within the ceramic substrate region, extract the highest value region, and record the center point of the highest value region. Xm , Ym ) represents the location of the highest point on the ceramic substrate. Xm , Ym The pixel value at () is the height of the highest point on the ceramic substrate. Hm ; Traverse the pixel values ​​of each pixel within the background horizontal plane region, calculate the average height of the entire background horizontal plane, and obtain the average height value of the background horizontal plane. H0 ;

[0148] The third calculation module includes a fifth relation, which is configured to: based on the highest point of the ceramic substrate ( Xm , Ym Height value at ) Hm The highest point calculated using the first calculation module ( Xm , Ym Thickness value at ) Tm、 and the average height of the background horizontal plane area H0 The warpage of the ceramic substrate was calculated. Warp = (Hm - Tm - H0） / Height .

[0149] Example 3:

[0150] This embodiment provides a device, which includes:

[0151] Memory, used to store computer programs;

[0152] 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 power electronic module. The method for measuring the size and warpage of a ceramic substrate for heat dissipation of a high-power power electronic module is the same as the method described in Embodiment 1.

[0153] Example 4:

[0154] This embodiment provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, it measures the size, thickness, and warpage deformation of a ceramic substrate for heat dissipation of a high-power power electronic module. The steps for measuring the size, thickness, and warpage deformation of the ceramic substrate for heat dissipation of a high-power power electronic module are the same as those described in Embodiment 1.

[0155] 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 within the protection scope of the present invention.

Claims

1. A method for measuring the dimensions and warpage of a ceramic substrate used for heat dissipation in high-power power electronic modules, characterized in that, Includes 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 ceramic substrate surface. S2. Divide the height image into the ceramic substrate area and the background horizontal plane area; S3. After rotating and aligning the ceramic substrate area, calculate the width of the ceramic substrate. Width and height Height ; S4. Based on the height image, measure the position of the highest point of the ceramic substrate, the height value Hm at the highest point, and the horizontal height value H0 of the background horizontal plane area. Use a through-beam laser displacement meter to measure the thickness value Tm at the highest point of the ceramic substrate. Calculate the warp of the ceramic substrate based on the height value Hm, the thickness value Tm, and the horizontal height value H0. This includes the following steps: S41. Traverse the pixel value of each pixel in the ceramic substrate area. The pixel value is the height value of the ceramic substrate position corresponding to the pixel. The position with the largest pixel value is the position with the highest warping on the ceramic substrate. S42. Use binarization to extract the highest pixel, and group together suspected pixels with the same height value range as suspected areas; S43. Use Blob analysis to extract and label the connected components of suspected regions. Each labeled Blob represents a suspected target. S44. Based on the width, height, and area characteristics, suspected targets are screened, and the largest area that is ultimately retained is the highest area of ​​the ceramic substrate, and the center point of the highest area ( Xm , Ym () represents the position of the highest point on the ceramic substrate. Xm , Ym The pixel value at () is the height of the highest point on the ceramic substrate. Hm ; S45. Traverse the pixel value of each pixel within the background horizontal plane region. The pixel value is the height value of the background horizontal plane position corresponding to that pixel. Calculate the average height of the entire background horizontal plane to obtain the horizontal plane height value of the background horizontal plane region. H0 ; S46. Using a through-beam laser displacement meter to measure ( Xm , Ym Thickness value at ) Tm ; S47. Calculate the warpage of the ceramic substrate. Warp = (Hm) - Tm - H0） / Height .

2. The method for measuring the dimensions and warpage of a ceramic substrate for heat dissipation in high-power power electronic modules according to claim 1, characterized in that, Step S2 includes the following steps: S21. Smooth and denoise the height image using a Gaussian filter; S22. Calculate the gradient and direction of each pixel in the height image, and filter each pixel to retain the pixels with extreme gradient values. The pixel positions of local extreme values ​​are edge candidate points. S23. Set a threshold. Edge candidate points with an absolute value greater than the threshold are considered as image edges. Divide image edge pixels into strong edges, weak edges, and non-edges. S24. Retain strong edge pixels and discard non-edge pixels; S25. Analyze the positional relationship between weak edges and strong edges, and perform secondary screening on weak edges; S26. The retained weak edge pixels are processed together with the strong edge pixels to form a complete edge outline, thus obtaining the ceramic substrate area. The remaining area is the background horizontal plane area.

3. The method for measuring the dimensions and warpage of a ceramic substrate for heat dissipation in high-power power electronic modules according to claim 1, characterized in that, Step S3 includes the following steps: S31. Let the ceramic substrate region be Region, and calculate the row coordinates of the center point of Region. Row Column coordinates Column and the slant angle of the circumscribed rectangle Phi ; S32, with ( Column , Row ) as the center of rotation, with - Phi Define an affine matrix for the rotation angle, and after performing an affine transformation on the Region, obtain the rotated and aligned ceramic substrate region, denoted 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 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 precision in the Y direction Yaccuracy The width of the ceramic substrate was calculated. Width and height Height : Width = Xpixel * Xaccuracy ； Height = Ypixel * Yaccuracy 。 4. The method for measuring the dimensions and warpage of a ceramic substrate for heat dissipation in high-power power electronic modules according to claim 1, characterized in that, The method for measuring thickness values ​​using a through-beam laser displacement meter includes the following steps: S461. A cutout fixture and a thickness calibration plate are provided. An upper laser displacement meter is installed above the cutout fixture, and a lower laser displacement meter is installed below it. The thickness of the thickness calibration plate is... t ; S462. Place the thickness calibration plate on the hollow jig. Randomly select several measurement points on the thickness calibration plate. For each measurement point on the thickness calibration plate, use an upper laser displacement gauge to measure the distance to the upper surface of the thickness calibration plate. d1 The distance to the lower surface of the thickness calibration plate was measured using a lower laser displacement meter. d2 ; S463. For each measurement point on the thickness calibration plate, calculate the single-point installation distance between the upper and lower laser displacement gauges. z = d1 + d2 + t The average value is used to obtain the installation distance between the upper and lower laser displacement gauges. Z ; S464. Place the ceramic substrate on the hollowed-out fixture, and for each measuring point on the ceramic substrate, use an upper laser displacement meter to measure the distance from the upper surface of the measuring point to the upper surface of the measuring point. D1 The lower distance of the measuring point on the lower surface was measured using a lower laser displacement meter. D2 ; S465. Calculate the thickness value at each measurement point on the ceramic substrate. T = Z - ( D1 + D2 The average thickness of the ceramic substrate is obtained by taking the average of the thickness values ​​at all measurement points.

5. The method for measuring the dimensions and warpage of a ceramic substrate for heat dissipation in high-power power electronic modules according to claim 1, characterized in that, It also includes: step S5, measuring the thickness of the ceramic substrate using a through-beam laser displacement meter, including the following steps: S51. Provide a cutout fixture and a thickness calibration plate, with an upper laser displacement meter installed above the cutout fixture and a lower laser displacement meter installed below it; S52. Calculate the installation distance between the upper and lower laser displacement gauges using a thickness calibration plate. Z ; S53. Place the ceramic substrate on the hollowed-out fixture, and for each measuring point on the ceramic substrate, use an upper laser displacement meter to measure the distance from the upper surface of the measuring point to the upper surface of the measuring point. D1 The lower distance of the measuring point on the lower surface was measured using a lower laser displacement meter. D2 ; S54. Calculate the thickness value at each measurement point. T = Z - ( D1 + D2 The average thickness of the ceramic substrate is obtained by taking the average of the thickness values ​​at all measurement points.

6. The method for measuring the dimensions and warpage of a ceramic substrate for heat dissipation in high-power power electronic modules according to claim 5, characterized in that, Step S52 includes the following steps: S521. Place the thickness calibration plate on the hollow jig and use the upper laser displacement gauge to measure the distance to the upper surface of the thickness calibration plate. d1 The distance to the lower surface of the thickness calibration plate was measured using a lower laser displacement meter. d2 ; S522, Based on the thickness of the calibration plate t Measured distance d1 and distance d2 The single-point installation distance between the upper and lower laser displacement gauges was calculated. z = d1 + d2 + t ; S523. Randomly select several measurement points on the thickness calibration plate, and repeat steps S521 to S522 to obtain several single-point installation spacings. z The average value is used to obtain the installation distance between the upper and lower laser displacement gauges. Z .

7. A device for measuring the dimensions and warpage of a ceramic substrate used for heat dissipation in high-power power electronic modules, characterized in that, It includes: Hollow jig; The upper laser displacement gauge and the lower laser displacement gauge are arranged opposite to each other on the upper and lower sides of the hollowed-out fixture; The upper laser displacement meter is configured to measure the distance to the upper surface of an object placed on the hollowed-out fixture, and the lower laser displacement meter is configured to measure the distance to the lower surface of an object placed on the hollowed-out fixture. A thickness calibration plate, with a thickness of t, is configured to assist in calculating the installation distance between the upper laser displacement gauge and the lower laser displacement gauge. Z ; A 3D line laser measuring instrument is configured to acquire a height image of the surface of the object being measured; The first calculation module includes a first relation, a second relation, and a third relation; the first relation is configured as follows: based on the distance measured by the upper laser displacement gauge to the upper surface of the thickness calibration plate placed in the hollow fixture. d1 The distance measured by the laser displacement gauge to the lower surface of the thickness calibration plate. d2 And the thickness of the thickness calibration plate t The summation of these three factors yields the single-point installation spacing between the upper and lower laser displacement gauges. The second formula is configured as follows: based on multiple single-point installation spacings, the average of these spacings is used to calculate the installation spacing between the upper and lower laser displacement gauges. Z The third relation is configured as follows: based on the installation spacing Z, the upper distance measured by the upper laser displacement gauge to the upper surface of the measuring point on the ceramic substrate of the hollow fixture. D1 And the lower distance measured by the lower laser displacement meter to the lower surface of the measuring point on the ceramic substrate. D2 The thickness value of the ceramic substrate at that measurement point was calculated. T = Z -( D1 + D2 ); The first processing module is configured to divide the height image into a ceramic substrate region and a background horizontal plane region. The second processing module is configured to rotate and straighten the ceramic substrate region to obtain a rotated and straightened ceramic substrate region, denoted as RotateRegion. The second calculation module includes a fourth relation, which is configured to: calculate based on the number of pixels occupied by the width of the RotateRegion. Xpixel and the number of pixels occupied by height Ypixel And the pixel accuracy in the X direction of the 3D line laser measuring instrument. Xaccuracy and pixel precision in the Y direction Yaccuracy, The width of the ceramic substrate was calculated. Width = Xpixel * Xaccuracy high Height = Ypixel * Yaccuracy ; The third processing module is configured to: traverse the pixel values ​​of each pixel within the ceramic substrate region, extract the highest value region, and record the center point of the highest value region. Xm , Ym ) represents the location of the highest point on the ceramic substrate. Xm , Ym The pixel value at () is the height of the highest point on the ceramic substrate. Hm ; Traverse the pixel values ​​of each pixel within the background horizontal plane region, calculate the average height 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 relation, which is configured to: based on the highest point of the ceramic substrate ( Xm , Ym Height value at ) Hm The highest point calculated using the first calculation module ( Xm , Ym Thickness value at ) Tm、 and the average height value of the background horizontal plane area H0 The warpage of the ceramic substrate was calculated. Warp = (Hm) - Tm - H0） / Height .

8. A device for measuring the dimensions and warpage of a ceramic substrate used for heat dissipation in high-power power electronic modules, characterized in that, It includes: Memory, used to store 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 as described in any one of claims 1 to 6.

9. 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 as described in any one of claims 1 to 6.

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