Chip bonding wire three-dimensional measurement system based on inner cavity reflection camera system

Abstract

The utility model provides a chip bonding wire three-dimensional measurement system based on an inner cavity reflection camera system. The chip bonding wire three-dimensional measurement system comprises a microscope lens, a reflector cavity, a relay lens, an industrial camera and an illumination module. Two parallel plane mirrors are arranged in the reflector cavity and used for separating a first real image imaged by the microscope lens into three independent light paths to form a three-view virtual image, and the three-view virtual image is transmitted to a photosensitive chip of the industrial camera through the relay lens at the amplification factor of 1: 1, so that three-view images are acquired through single exposure. The system is matched with a computer to carry out optical flow calculation, point cloud fusion and three-dimensional reconstruction, a three-dimensional grid model with texture colors is generated, and high-precision and non-contact measurement of the multi-layer lead shielding structure is achieved. The system is compact in structure, easy and convenient to install and adjust and suitable for on-line detection of bonding and packaging of vehicle-gauge-level chips.

Description

A three-dimensional measurement system for chip bonding wires based on an internal cavity reflection camera system Technical Field

[0001] This utility model relates to the field of three-dimensional measurement technology, and in particular to a three-dimensional measurement system for chip bonding wires based on an internal cavity reflection camera system. Background Technology

[0002] In the field of semiconductor packaging, high-precision three-dimensional measurement of the spatial morphology of micron-level gold wires is essential for verifying the reliability of bonding processes. Existing detection methods mainly include five intelligent detection techniques: structured light / binocular vision, spectral confocal scanning, laser line scanning, white light interferometry, and light field cameras. However, these methods are limited by issues such as depth of field, mechanical scanning efficiency, damage from strong light, cost, and resolution degradation, making it difficult to simultaneously balance speed, accuracy, and adaptability to scenarios with multi-layer lead occlusion.

[0003] However, as the number of bonding wire layers in automotive-grade chips increases from 1-2 layers to 4-5 layers, the testing tasks place higher demands on depth penetration, micron-level spatial resolution, and online processing speed. Traditional solutions are still insufficient in terms of depth measurement capability, algorithm anti-interference, and overall integration cost, and cannot meet the urgent needs of high-end manufacturing industries for efficient, low-cost, and easily integrated testing equipment. Summary of the Invention

[0004] To overcome the shortcomings of the existing technology, the purpose of this utility model is to provide a chip bonding wire three-dimensional measurement system based on an internal cavity reflection camera system, which can realize three-view synchronous imaging and high-precision three-dimensional reconstruction of chip bonding wires under the conditions of a single camera and a single exposure, improve detection efficiency, reduce system cost, and enhance the measurement adaptability to multi-layer shielded wire structures.

[0005] To achieve the above objectives, this utility model provides the following solution:

[0006] A three-dimensional measurement system for chip bonding wires based on an internal cavity reflection camera system, comprising:

[0007] An industrial camera, wherein the housing of the industrial camera is mounted at the end of the optical path, and a photosensitive chip is fixedly installed inside the industrial camera. The photosensitive chip is located on the image plane coaxial with the optical axis of the relay lens and is used to receive the projected three-view image.

[0008] The microscope lens has an object side that magnifies and images the bonding wires of the chip under test, and an image side that forms a first real image on the first image plane.

[0009] The reflecting mirror cavity is located at the image-side focal plane of the microscope head and is used to separate the first real image into three independent optical paths—left, center, and right—to form virtual images from three different perspectives.

[0010] A relay lens, the optical center of which is located in the outgoing light path of the reflector cavity, is used to image the three-view virtual image proportionally onto different areas of the photosensitive chip;

[0011] A lens extension ring is disposed between the mirror cavity and the relay lens to fine-tune the axial distance between the mirror cavity and the relay lens in order to obtain the optimal imaging focal plane;

[0012] The illumination module emits light that is diffused and then coaxially aligned with the optical axis of the microscope head to illuminate the chip under test, thereby reducing specular reflection interference.

[0013] A computer, connected to the industrial camera, is used to process data including three-view images acquired by the industrial camera and generate a three-dimensional structure result of the bonding wires of the chip under test.

[0014] Preferably, a first plane mirror and a second plane mirror are arranged parallel to each other along the optical axis inside the reflector cavity, and the distance between the first plane mirror and the second plane mirror is equal to one-third of the effective width of the photosensitive chip.

[0015] Preferably, the object distance and image distance of the relay lens are equal to achieve a 1:1 magnification ratio.

[0016] Preferably, the lens extension ring is threadedly connected to the reflector cavity and the relay lens to facilitate axial fine-tuning and modular assembly / disassembly.

[0017] Preferably, the lighting module includes a variable aperture; the variable aperture is used to adjust the numerical aperture of the lighting to adapt to chips with different package heights.

[0018] Preferably, the industrial camera is connected to the relay lens via a preset interface.

[0019] Preferably, the diagonal dimension of the photosensitive chip is greater than the total width of the three-view virtual image on the image plane.

[0020] According to the specific embodiments provided by this utility model, the following technical effects are disclosed:

[0021] This invention provides a three-dimensional measurement system for chip bonding wires based on an internal cavity reflection camera system, comprising: an industrial camera, the housing of which is mounted at the end of the optical path, and a photosensitive chip fixedly mounted inside the industrial camera, the photosensitive chip being located on the image plane coaxial with the optical axis of a relay lens, for receiving projected three-view images; a microscope head, the object side of which magnifies and images the chip bonding wire under test, the image side of which forms a first real image on the first image plane; a reflecting mirror cavity, disposed at the focal plane of the image side of the microscope head, for separating the first real image into three independent optical paths (left, center, and right) and forming three-view virtual images respectively; and a relay lens. The microscope includes a microscope head, where the optical center of the relay lens is located on the outgoing light path of the mirror cavity, used to image the three-view virtual image proportionally onto different areas of the photosensitive chip; a lens extension ring, disposed between the mirror cavity and the relay lens, used to fine-tune the axial distance between the mirror cavity and the relay lens to obtain the optimal imaging focal plane; an illumination module, whose outgoing light is diffused and coaxially aligned with the optical axis of the microscope head to illuminate the chip under test, thereby reducing specular reflection interference; and a computer, connected to the industrial camera, used to process the data containing the three-view images acquired by the industrial camera and generate a three-dimensional structural result of the bonding wires of the chip under test. This invention enables simultaneous three-view imaging and high-precision three-dimensional reconstruction of chip bonding wires under single-camera and single-exposure conditions, improving detection efficiency, reducing system costs, and enhancing the adaptability to measurement of multi-layer obscured wire structures. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 is a schematic diagram of the system structure provided in an embodiment of the present utility model;

[0024] Figure 2 is a schematic diagram of the position of the plane mirror and its fixing element provided in the embodiment of this utility model;

[0025] Figure 3 is a schematic diagram of the original image and processing result of three-dimensional measurement of chip bonding wires under suitable light source illumination provided by an embodiment of the present invention.

[0026] Figure 4 is a schematic diagram of the principle of obtaining a three-view image of the photographed object provided by an embodiment of the present invention.

[0027] Explanation of reference numerals in the attached figures:

[0028] 10. Internal cavity reflection camera system; 20. Industrial camera; 21. Photosensitive chip; 30. Relay lens; 40. Reflecting mirror cavity; 41. First plane mirror and second plane mirror; 42. Lens fixing element; 50. Lens extension ring; 60. Microscope lens; 70. Illumination module; 80. Chip under test; 90. Computer; 100. 3D point cloud reconstruction result. Detailed Implementation

[0029] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0030] The purpose of this invention is to provide a three-dimensional measurement system for chip bonding wires based on an internal cavity reflection camera system. This system can achieve simultaneous three-view imaging and high-precision three-dimensional reconstruction of chip bonding wires under single-camera and single-exposure conditions, thereby improving detection efficiency, reducing system cost, and enhancing the measurement adaptability to multi-layer shielded wire structures.

[0031] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] As shown in Figures 1 to 3, the cavity reflection camera system 10 includes, along the optical axis from the object side to the image side, a microscope head 60, a reflecting mirror cavity 40, a relay lens 30, and an industrial camera 20. A photosensitive chip 21 is fixedly mounted inside the industrial camera 20. The photosensitive surface of the photosensitive chip 21 is perpendicular to the optical axis and located at the image plane. The working distance of the microscope head 60 is matched to the packaging height of the chip 80 under test, for forming a first real image on its image-side focal plane.

[0033] The reflecting mirror cavity 40 is located at the image-side focal plane of the microscope head 60. The distance between the first plane mirror and the second plane mirror 41, which are arranged in parallel inside the cavity, is equal to one-third of the effective width of the photosensitive chip 21. The first plane mirror and the second plane mirror 41 separate the first real image into three independent optical paths: left, center, and right, forming a three-view virtual image and guiding it to the relay lens 30.

[0034] In this embodiment, by adding lens fixing elements 42 to both ends of the first plane mirror and the second plane mirror 41, the first plane mirror and the second plane mirror 41 are made parallel, and the distance between the two plane mirrors is fixed. The outer diameter of the lens fixing element 42 matches the inner diameter of the reflector cavity 40, thereby fixing the position of the lens.

[0035] The relay lens 30 is installed between the mirror cavity 40 and the industrial camera 20, with its object distance and image distance being equal to achieve a 1:1 magnification ratio, ensuring that the three-view virtual image is distorted when projected onto the image sensor 21. The lens extension ring 50 is threaded and placed between the mirror cavity 40 and the relay lens 30 to fine-tune the axial distance between them, so that the system 10 can still obtain the optimal focal plane under different temperature drift or component tolerance conditions.

[0036] The illumination module 70 is an integrating sphere white light source. After diffusion, the emitted light is coaxial with the optical axis of the microscope lens 60 to illuminate the chip under test 80, reducing artifacts caused by specular reflection. The illumination module 70 can be equipped with a variable aperture to adjust the numerical aperture to adapt to different package heights.

[0037] The chip under test, 80, has a typical wire-bonded package structure with 1-4 gold wire layers and a minimum interlayer spacing of ≥15µm. System 10 can complete the three-dimensional measurement of this complex multilayer wire structure without the need for additional mechanical sweeping.

[0038] The industrial camera 20 simultaneously acquires raw image files containing three-view virtual images using a single exposure method. The computer 90 pre-stores the whiteboard brightness compensation matrix and generates a textured, colored 3D mesh model 100 according to the following process:

[0039] Brightness normalization: The compensation matrix is ​​called to perform brightness normalization on the original image;

[0040] Viewpoint segmentation: The normalized image is segmented into three virtual image sub-images: left, center, and right, according to the principle of equal division of the width of the photosensitive chip 21.

[0041] Optical flow calculation: The displacement vector field of virtual images at any two viewpoints is calculated using the dense optical flow method;

[0042] Point cloud fusion: fusing three sets of vector fields to generate three-dimensional point cloud data;

[0043] Surface reconstruction: After performing statistical filtering on the point cloud, a three-dimensional mesh model with texture and color is generated by using the Poisson surface reconstruction algorithm and Delaunay triangulation.

[0044] Dimensioning and Output: The computer 90 performs defect judgment on the three-dimensional mesh model 100 according to the preset dimensional tolerance threshold and outputs an inspection report.

[0045] As shown in Figure 3, 3-a is the original image of the measurement area captured by the cavity reflection camera system, 3-b is the left-view image, 3-c is the middle-view image, 3-d is the right-view image, 3-e is the parallax map, 3-f is the 3D point cloud map, and 3-g is the 3D point cloud map with texture and color.

[0046] As shown in Figure 4, S oIt is the main lens object distance, S i It is the main lens image distance, S Ro It is the object distance of the relay lens, S Ri It is the image distance of the relay lens, L m It is the distance between two plane mirrors, L sen It refers to the size of the camera's image sensor.

[0047] The principle behind an internal cavity reflection camera system for obtaining three-view images of a photographed object is as follows: the main lens selects a lens with an appropriate magnification factor based on the size of the object. The relay lens has a magnification factor of 1, therefore the image distance equals the object distance, i.e., S. Ro =S Ri The length of the reflecting cavity with the plane mirror is S. Ro They are located between the rear focal position of the main lens and the main lens of the relay lens, and are arranged in a dense array. The distance between the two plane mirrors of the reflecting cavity is 1 / 3 of the size of the image sensor, i.e., L. m =1 / 3L sen The imaging optical path of the object A is shown in the figure. After passing through the main lens, a real image A is formed. i0 The real image A i0 The two plane mirrors will each form a virtual image A. i1 and A i2 A i0 A i1 and A i2 After passing through a relay lens, three images A are formed on the image sensor respectively. i0 '、A i1 'and A i2 From the optical path diagram, it can be seen that A i0 'It is formed by the convergence of light in the center of the main lens, A' i1 'It is formed by the convergence of light from the lower part of the main lens, A' i2 'It is formed by the convergence of light from the upper part of the main lens.' (A is visible.) i0 '、A i1 'and A i2 The system captures images of object A from three different perspectives: the middle, lower, and upper parts of the main lens. Therefore, a single photograph from this system can provide images of the object from three different viewpoints. Furthermore, the system has a simple structure, controllable hardware costs, and low requirements for cameras, light sources, and shooting environments, providing a solution for online micron-level 3D reconstruction and measurement of chip bonding wires.

[0048] This invention employs a structure in which a reflecting mirror cavity 40 is set on the image side of the microscope lens 60, and a relay lens 30 is connected in series after the reflecting mirror cavity 40. This structure effectively separates multiple perspective images captured by the microscope lens 60 and transmits them along different optical paths to the photosensitive chip 21 of the industrial camera 20, thereby achieving simultaneous recording of three-view virtual images in a single exposure. Compared to existing conventional multi-camera or time-division acquisition schemes, this invention has a more compact structure and can complete three-view image acquisition with a single industrial camera 20, avoiding common problems such as occlusion and insufficient depth of field in multi-view systems, and significantly improving system adaptability and detection efficiency.

[0049] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0050] This document uses specific examples to illustrate the principles and implementation methods of this utility model. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this utility model. Furthermore, those skilled in the art will recognize that, based on the ideas of this utility model, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this utility model.

Claims

1. A three-dimensional measurement system for chip bonding wires based on an internal cavity reflection camera system, characterized in that, include: An industrial camera, the housing of which is mounted at the end of the optical path, has a photosensitive chip fixedly installed inside. The photosensitive chip is located on the image plane coaxial with the optical axis of the relay lens and is used to receive projected three-view images. A microscope lens has its object-side surface magnifying and imaging the bonding wires of the chip under test, and its image-side surface forming a first real image on the first image plane. A reflecting mirror cavity is located at the focal plane of the image-side surface of the microscope lens and is used to separate the first real image into three independent optical paths (left, center, and right) and form three-view virtual images respectively. A relay lens has its optical center located on the exit optical path of the reflecting mirror cavity and is used to image the three-view virtual images proportionally onto different areas of the photosensitive chip. A lens extension ring is disposed between the mirror cavity and the relay lens to fine-tune the axial distance between the mirror cavity and the relay lens in order to obtain the optimal imaging focal plane; An illumination module, whose emitted light is diffused and coaxially aligned with the optical axis of the microscope head to illuminate the chip under test, thereby reducing specular reflection interference; a computer, connected to the industrial camera, for processing data including three-view images acquired by the industrial camera and generating a three-dimensional structural result of the bonding wires of the chip under test.

2. The chip bonding wire three-dimensional measurement system based on an internal cavity reflection camera system according to claim 1, characterized in that, A first plane mirror and a second plane mirror are arranged parallel to each other along the optical axis inside the reflector cavity. The distance between the first plane mirror and the second plane mirror is equal to one-third of the effective width of the photosensitive chip.

3. The chip bonding wire three-dimensional measurement system based on an internal cavity reflection camera system according to claim 1, characterized in that, The object distance and image distance of the relay lens are equal to achieve a 1:1 magnification ratio.

4. The chip bonding wire three-dimensional measurement system based on an internal cavity reflection camera system according to claim 1, characterized in that, The lens extension ring is connected to the reflector cavity and the relay lens by a threaded connection, which facilitates axial fine adjustment and modular assembly and disassembly.

5. The chip bonding wire three-dimensional measurement system based on an internal cavity reflection camera system according to claim 1, characterized in that, The lighting module includes a variable aperture; the variable aperture is used to adjust the numerical aperture of the lighting to adapt to chips with different package heights.

6. The chip bonding wire three-dimensional measurement system based on an internal cavity reflection camera system according to claim 1, characterized in that, The industrial camera is connected to the relay lens via a pre-defined interface.

7. The chip bonding wire three-dimensional measurement system based on an internal cavity reflection camera system according to claim 1, characterized in that, The diagonal dimension of the photosensitive chip is greater than the total width of the three-view virtual image on the image plane.

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