A three-dimensional integrated solder joint defect detection method based on a fresnel acoustic lens

Abstract

The present application relates to the technical field of process detection of multilayer chip stacking and flip bonding process, and more particularly to a three-dimensional integrated solder joint defect detection method based on a Fresnel acoustic lens, step S1: install the multilayer stacked chip on a heating disc for heating bonding, a three-dimensional moving platform drives the ultrasonic probe and the Fresnel lens to move to a suitable position, so that the ultrasonic emitted by the ultrasonic probe falls on the chip to be detected through the focal point of the Fresnel lens; step S2: start the ultrasonic probe detection, the ultrasonic probe receives the ultrasonic waves reflected by the chip and converts them into electrical signals, which are transmitted to the upper computer for analysis and three-dimensional imaging; step S3: according to the detection requirement, repeatedly move the ultrasonic probe and the Fresnel lens to different positions to realize real-time detection of the bonding condition of each region of the chip; the solder joint defects can be accurately positioned and detected during the bonding process of the multilayer stacked chip.

Description

Technical Field

[0001] This invention relates to the field of process inspection technology for multilayer chip stacking and flip bonding processes, and more specifically to a three-dimensional integrated solder joint defect detection method based on Fresnel acoustic lenses. Background Technology

[0002] 3D packaging is one of the core processes in advanced integrated circuit packaging technology. It involves vertically stacking and interconnecting multiple chips to form small-sized, low-interconnection-distance, multifunctional integrated circuit devices. This packaging method can integrate higher-performance devices within a limited space while reducing the requirements for chip manufacturing processes, combining high performance with low cost. However, changes in packaging structure and the increase in the number of packaging layers lead to a significant increase in the number of solder joints within the device, and a substantial increase in the probability of defects such as cold solder joints, voids, and cracks. Existing defect detection methods, such as micro-CT, X-ray, and optical inspection, can only achieve offline detection and suffer from low accuracy, long inspection time, severe chip damage, and lack of process information, significantly reducing the yield and production efficiency of integrated circuits. Therefore, there is an urgent need for a precise method for locating and detecting solder joint defects during the bonding process of multi-layer stacked chips. Summary of the Invention

[0003] The purpose of this invention is to provide a three-dimensional integrated solder joint defect detection method based on Fresnel acoustic lenses, which can accurately locate and detect solder joint defects during the bonding process of multilayer stacked chips.

[0004] The objective of this invention is achieved through the following technical solution:

[0005] A three-dimensional integrated solder joint defect detection method based on Fresnel acoustic lenses, the method comprising the following steps:

[0006] Step S1: The multilayer stacked chip is mounted on the heating plate for heating bonding. The three-dimensional moving platform moves the ultrasonic probe and Fresnel lens to the appropriate position so that the ultrasonic waves emitted by the ultrasonic probe fall on the chip to be tested position after passing through the focal point of the Fresnel lens.

[0007] Step S2: Start the ultrasonic probe detection. The ultrasonic probe receives the ultrasonic waves reflected by the chip and converts them into electrical signals, which are then transmitted to the host computer for analysis and 3D imaging.

[0008] Step S3: According to the detection requirements, repeatedly move the ultrasonic probe and Fresnel lens to different positions to realize real-time detection of the bonding status of each area of ​​the chip;

[0009] The Fresnel lens is made of metallic or non-metallic materials and is used to refract ultrasonic waves, so that the fundamental wave and harmonic focus converges at the chip detection position.

[0010] The Fresnel lens consists of a series of concentric rings, which are made by etching rigid material. Two adjacent rings form a slit, which gradually narrows from the inside to the outside. When the ultrasonic wave passes through the slit, it is diffracted, causing the sound waves on both sides to focus towards the center, thus increasing the sound energy flux density.

[0011] The ultrasonic probe is one of a linear scanning probe, a mechanical sector scanning probe, or a phased array ultrasonic probe, and has waterproof and high-frequency characteristics.

[0012] The three-dimensional moving platform is driven by a drive motor, and the three-dimensional moving platform can drive the Fresnel lens and the ultrasonic probe to move in the X, Y and Z directions.

[0013] The heating plate includes a heating wire, and the heating plate heats and bonds the stacked chips;

[0014] The ultrasonic probe is electrically connected to the host computer for signal transmission and processing;

[0015] An integrated three-dimensional weld defect detection device includes a base and a heating plate. A three-dimensional moving platform is installed on the base and driven by a drive motor. An ultrasonic probe and a Fresnel lens are installed on the three-dimensional moving platform. A heat insulation plate is fixedly connected to the bottom of the heating plate, and the Fresnel lens is located on the lower side of the heat insulation plate.

[0016] The three-dimensional moving platform, drive motor, base, Fresnel lens and ultrasonic probe are all set in a watertight chamber, and the watertight chamber is connected to a water pump through a water pipe.

[0017] A split-type three-dimensional integrated weld joint defect detection device includes a base and a heating plate. A three-dimensional moving platform is installed on the base and driven by a drive motor. An ultrasonic probe and a Fresnel lens are installed on the three-dimensional moving platform. A heat insulation plate is fixedly connected to the bottom of the heating plate, and the Fresnel lens is located on the lower side of the heat insulation plate.

[0018] The three-dimensional mobile platform is equipped with a watertight chamber that covers a Fresnel lens and an ultrasonic probe. The top of the watertight chamber is equipped with a flexible water bladder, which is used to fit against the heat insulation plate during detection to ensure the continuity of the sound wave propagation medium. The watertight chamber is connected to an external water pump through a water pipe.

[0019] The beneficial effects of this invention are as follows:

[0020] Overcoming the limitations of existing methods that only enable offline inspection, resulting in missing effective information and low processing efficiency, this paper proposes an integrated method for simultaneous bonding and in-situ inspection based on incident wave bonding and reflected wave detection. Compared with existing inspection schemes, this method significantly improves the timeliness and accuracy of inspection. By using a Fresnel lens to focus ultrasound emitted by an ultrasonic probe onto different positions and heights of the chip, and receiving and processing reflected waves, feature points and defects can be detected during the bonding process of multilayer stacked chips, ensuring processing quality and timely detection of potential problems during bonding. From a practical production perspective, real-time precision inspection of key points can improve detection accuracy while maintaining efficiency. Detecting defects can dynamically reflect the microscopic process of multilayer chip bonding. Based on the detection results at different time periods, the bonding process of multilayer stacked chips can be optimized, improving the processing yield and providing a data foundation for subsequent optimization of bonding methods. Attached Figure Description

[0021] The present invention will now be described in further detail with reference to the accompanying drawings and specific implementation methods.

[0022] Figure 1 This is a schematic diagram of the three-dimensional integrated weld joint defect detection method based on Fresnel acoustic lenses according to the present invention;

[0023] Figure 2 This is a schematic diagram of the integrated three-dimensional weld defect detection device of the present invention;

[0024] Figure 3 This is a schematic diagram of the structure of the split-type three-dimensional integrated weld point defect detection device of the present invention;

[0025] Figure 4 This is a schematic diagram of the Nelson lens structure of the present invention.

[0026] In the diagram: 1. Heating plate; 2. Insulation plate; 3. Three-dimensional moving platform; 4. Drive motor; 5. Base; 6. Fresnel lens; 7. Ultrasonic probe; 8. Watertight chamber; 9. Flexible water bag. Detailed Implementation

[0027] The present invention will now be described in further detail with reference to the accompanying drawings.

[0028] like Figure 1 As shown below, the steps and functions of a three-dimensional integrated weld joint defect detection method based on Fresnel acoustic lenses will be described in detail.

[0029] A three-dimensional integrated solder joint defect detection method based on Fresnel acoustic lenses, the method comprising the following steps:

[0030] Step S1: The multi-layer stacked chip is mounted on the heating plate 1 for heating and bonding. The three-dimensional moving platform 3 moves the ultrasonic probe 7 and Fresnel lens 6 to a suitable position so that the ultrasonic waves emitted by the ultrasonic probe 7 pass through the focal point of the Fresnel lens 6 and fall on the chip to be tested position.

[0031] Step S2: Turn on the ultrasonic probe 7 for detection. The ultrasonic probe 7 receives the ultrasonic waves reflected by the chip and converts them into electrical signals, which are then transmitted to the host computer for analysis. Higher vertical resolution is achieved for three-dimensional imaging using technologies including but not limited to three-dimensional reconstruction image technology.

[0032] Step S3: According to the detection requirements, repeatedly move the ultrasonic probe 7 and Fresnel lens 6 to different positions to realize real-time detection of the bonding status of each area of ​​the chip;

[0033] By focusing the ultrasonic waves emitted by the ultrasonic probe 7 onto different positions and heights of the chip through the Fresnel lens 6, and receiving and processing the reflected waves, feature points and defects can be detected during the bonding process of multilayer stacked chips. This ensures processing quality and timely detection of potential problems during bonding. From a practical production perspective, real-time precision inspection of key points can improve detection accuracy while maintaining efficiency. Detecting defects can dynamically reflect the microscopic process of multilayer chip bonding. Based on the detection results at different time points, the bonding process of multilayer stacked chips can be optimized, improving the processing yield and providing a data foundation for subsequent optimization of bonding methods.

[0034] like Figure 4 As shown, the Fresnel lens 6 is made of metal or non-metal materials. The Fresnel lens 6 is mainly responsible for refracting the ultrasound emitted by the ultrasonic probe, so that the fundamental wave and harmonic focus are converged to the position of the chip that needs to be precisely inspected.

[0035] A Fresnel lens is an acoustic and optical focusing element composed of a series of concentric rings. Based on the principle of wave diffraction, the Fresnel acoustic lens is typically made by etching rings from a rigid material. Two adjacent rings form a slit, which narrows from the inside out. When used with an ultrasonic transducer, ultrasonic waves diffract after passing through the slit, causing the sound waves on both sides to focus towards the center, increasing the acoustic energy flux density. Simultaneously, the measurement area is reduced, thereby improving the spatial resolution of the measurement, thus achieving acoustic focusing. It is commonly used in imaging, ranging, or high-power ultrasound.

[0036] The three-dimensional moving platform 3 is driven by a drive motor 4. The three-dimensional moving platform 3 can drive the Fresnel lens 6 and the ultrasonic probe 7 to move in the X, Y, and Z directions. The three-dimensional moving platform 3 should also have functions including but not limited to waterproofing and position feedback, so that the ultrasonic probe 7 can move quickly and accurately to different positions to detect the chip. There are three drive motors 4, and each drive motor 4 has a lead screw fixedly connected to its output shaft. The three lead screws are distributed in the X, Y, and Z directions, and corresponding sliders and sliding seats are provided. The three sliding seats are connected to the three lead screws by threads. The first sliding seat is fixedly connected to the base 5, the second sliding seat is slidably connected to the first sliding seat, and the third sliding seat is slidably connected to the second sliding seat. Then, the Fresnel lens 6 and the ultrasonic probe 7 are installed on the third sliding seat. The first lead screw is rotatably connected to the base 5, the first sliding seat is threaded to the first lead screw, the second lead screw is rotatably connected to the first sliding seat, the second sliding seat is threaded to the second lead screw, the third lead screw is rotatably connected to the second sliding seat, and the third sliding seat is threaded to the third lead screw.

[0037] The three-dimensional moving platform 3 is mainly responsible for supporting and allowing the lens 6 to move within three translational degrees of freedom, increasing the scanning range of the ultrasonic probe 7, and simultaneously enabling the Fresnel lens 6 to focus at different heights of the chip to inspect the bonding of solder joints in each layer of the chip. Depending on the working environment, it should also have characteristics such as rust prevention and low resistance.

[0038] The drive motor 4 should have functions including but not limited to waterproofing and position feedback;

[0039] The heating plate 1 includes a heating wire, and the heating plate 1 heats and bonds the stacked chips;

[0040] The ultrasonic probe 7 mentioned above includes, but is not limited to, linear scanning probes, mechanical sector scanning probes, phased array ultrasonic probes, etc. It is mainly responsible for emitting high-frequency ultrasound, receiving the reflected sound waves from the chip and converting them into electrical signals for input to the host computer for subsequent analysis. Depending on the working environment, it should have waterproof and high-frequency characteristics.

[0041] like Figure 2 As shown, an integrated three-dimensional weld defect detection device includes a base 5 and a heating plate 1. A three-dimensional moving platform 3 is installed on the base 5. The three-dimensional moving platform 3 is driven by a drive motor 4. An ultrasonic probe 7 and a Fresnel lens 6 are installed on the three-dimensional moving platform 3. A heat insulation plate 2 is fixedly connected to the bottom of the heating plate 1. The Fresnel lens 6 is located on the lower side of the heat insulation plate 2.

[0042] The three-dimensional moving platform 3, drive motor 4, base 5, Fresnel lens 6 and ultrasonic probe 7 are all installed in the watertight chamber 8, and the watertight chamber 8 is connected to a water pump through a water pipe.

[0043] The watertight chamber 8 is responsible for providing the underwater environment required for testing and supporting the heating plate 1. The watertight chamber 8 has a certain degree of sealing and strength.

[0044] The heat insulation plate 2 is made of heat insulation material and is connected to the bottom of the heating plate 1 by bolts. It is mainly responsible for isolating the heat of the heating plate 1 from the ultrasonic precision inspection device below, reducing the impact of high temperature during chip bonding on ultrasonic inspection.

[0045] In use, water is introduced into the watertight chamber 8, which provides the underwater environment required for testing. The multi-layer stacked chip is mounted on the heating plate 1 for heating and bonding. The three-dimensional moving platform 3 moves the ultrasonic probe 7 and Fresnel lens 6 to a suitable position, so that the ultrasonic waves emitted by the ultrasonic probe 7 pass through the focal point of the Fresnel lens 6 and fall on the chip to be tested. The ultrasonic probe 7 is then activated to detect the ultrasonic waves reflected by the chip and converts them into electrical signals, which are then transmitted to the host computer for analysis. By moving the Fresnel lens 6 and ultrasonic probe 7 to different positions through the three-dimensional moving platform 3, real-time detection of the bonding status of each area of ​​the chip can be achieved.

[0046] like Figure 3 As shown, a split-type three-dimensional integrated weld defect detection device includes a base 5 and a heating plate 1. A three-dimensional moving platform 3 is installed on the base 5. The three-dimensional moving platform 3 is driven by a drive motor 4. An ultrasonic probe 7 and a Fresnel lens 6 are installed on the three-dimensional moving platform 3. A heat insulation plate 2 is fixedly connected to the bottom of the heating plate 1. The Fresnel lens 6 is located on the lower side of the heat insulation plate 2.

[0047] The three-dimensional moving platform 3 is equipped with a watertight chamber 8 covering a Fresnel lens 6 and an ultrasonic probe 7. The top of the watertight chamber 8 is equipped with a water bladder 9, which is used to fit against the heat insulation plate 2 during detection to ensure the continuity of the sound wave propagation medium. The watertight chamber 8 is connected to an external water pump through a water pipe.

[0048] The heat insulation plate 2 is made of heat insulation material and is connected to the bottom of the heating plate 1 by bolts. It is mainly responsible for isolating the heat of the heating plate 1 from the ultrasonic precision inspection device below, reducing the impact of the high temperature generated during chip bonding on ultrasonic inspection.

[0049] The watertight chamber 8 is fixed to the three-dimensional moving platform 3 with brackets and bolts, and has holes for connecting wires and water pumps. It is responsible for providing the underwater environment required for testing. The watertight chamber 8 has a certain degree of sealing.

[0050] The flexible water bladder 9 is made of elastic materials and is fixed to the top of the watertight chamber 8 by means including but not limited to adhesives and mechanical seals. When the watertight chamber 8 is filled with water and the test begins, it fits against the heat insulation plate 2 to facilitate the subsequent fine inspection process.

[0051] In use, water is introduced into the watertight chamber 8, which provides the underwater environment required for testing. After the watertight chamber 8 is filled with water, the flexible water bladder 9 is attached to the heat insulation plate 2 when testing begins. The multi-layer stacked chip is installed on the heating plate 1 for heating and bonding. The three-dimensional moving platform 3 moves the ultrasonic probe 7 and Fresnel lens 6 to a suitable position, so that the ultrasonic waves emitted by the ultrasonic probe 7 fall on the chip to be tested position after passing through the focal point of the Fresnel lens 6. The ultrasonic probe 7 is activated to detect the ultrasonic waves reflected by the chip and converts them into electrical signals, which are then transmitted to the host computer for analysis. By moving the Fresnel lens 6 and ultrasonic probe 7 to different positions through the three-dimensional moving platform 3, real-time detection of the bonding status of each area of ​​the chip can be achieved.

Claims

1. A three-dimensional integrated weld joint defect detection method based on Fresnel acoustic lenses, characterized in that: The method includes the following steps: Step S1: The multi-layer stacked chip is installed on the heating plate (1) for heating and bonding. The three-dimensional moving platform (3) drives the ultrasonic probe (7) and Fresnel lens (6) to a suitable position so that the ultrasonic waves emitted by the ultrasonic probe (7) fall on the chip to be tested position through the focal point of the Fresnel lens (6). Step S2: Turn on the ultrasonic probe (7) to detect. The ultrasonic probe (7) receives the ultrasonic waves reflected by the chip and converts them into electrical signals, which are then transmitted to the host computer for analysis and three-dimensional imaging. Step S3: According to the detection requirements, repeatedly move the ultrasonic probe (7) and Fresnel lens (6) to different positions to realize real-time detection of the bonding status of each area of ​​the chip.

2. The method for detecting defects in three-dimensional integrated solder joints based on Fresnel acoustic lenses according to claim 1, characterized in that: The Fresnel lens (6) is made of metal or non-metal materials and is used to refract ultrasonic waves so that the fundamental wave and harmonic focus are converged at the chip detection position.

3. The method for detecting defects in three-dimensional integrated solder joints based on Fresnel acoustic lenses according to claim 2, characterized in that: The Fresnel lens (6) consists of a series of concentric rings, which are made by etching rigid material. Two adjacent rings form a slit, which narrows from the inside to the outside. When the ultrasonic wave passes through the slit, it diffracts, causing the sound waves on both sides to focus towards the center, increasing the sound energy flux density.

4. The method for detecting defects in three-dimensional integrated solder joints based on Fresnel acoustic lenses according to claim 1, characterized in that: The ultrasonic probe (7) is one of a linear scanning probe, a mechanical sector scanning probe, or a phased array ultrasonic probe, and has waterproof and high-frequency characteristics.

5. The method for detecting defects in three-dimensional integrated solder joints based on Fresnel acoustic lenses according to claim 1, characterized in that: The three-dimensional moving platform (3) is driven by a drive motor (4), and the three-dimensional moving platform (3) can drive the Fresnel lens (6) and the ultrasonic probe (7) to move in the X, Y and Z directions.

6. The method for detecting defects in three-dimensional integrated solder joints based on Fresnel acoustic lenses according to claim 1, characterized in that: The heating plate (1) includes a heating wire, and the heating plate (1) heats and bonds the stacked chips.

7. The method for detecting defects in three-dimensional integrated solder joints based on Fresnel acoustic lenses according to claim 1, characterized in that: The method uses a three-dimensional integrated weld defect detection device, which includes a base (5) and a heating plate (1). A three-dimensional moving platform (3) is installed on the base (5). The three-dimensional moving platform (3) is driven by a drive motor (4). An ultrasonic probe (7) and a Fresnel lens (6) are installed on the three-dimensional moving platform (3). A heat insulation plate (2) is fixedly connected to the bottom of the heating plate (1). The Fresnel lens (6) is located on the lower side of the heat insulation plate (2).

8. The method for detecting defects in three-dimensional integrated solder joints based on Fresnel acoustic lenses according to claim 7, characterized in that: The three-dimensional moving platform (3), drive motor (4), base (5), Fresnel lens (6) and ultrasonic probe (7) are all located in the watertight chamber (8), which is connected to a water pump via a water pipe.

9. The method for detecting defects in three-dimensional integrated solder joints based on Fresnel acoustic lenses according to claim 7, characterized in that: The three-dimensional moving platform (3) is equipped with a watertight chamber (8) covering a Fresnel lens (6) and an ultrasonic probe (7). A flexible water bladder (9) is provided at the top of the watertight chamber (8) to fit against the heat insulation plate (2) during detection to ensure the continuity of the sound wave propagation medium. The watertight chamber (8) is connected to an external water pump through a water pipe.

10. A three-dimensional integrated solder joint defect detection method based on a Fresnel acoustic lens according to claim 8 or 9, characterized in that: The ultrasonic probe (7) is electrically connected to the host computer for signal transmission and processing.

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