Multilayer blind and buried hole PCB detection equipment

Abstract

The utility model relates to the technical field of printed circuit board nondestructive testing, in particular to multilayer blind buried hole PCB testing equipment which comprises a base, a testing frame is connected to the top of the base, a moving motor is installed in the testing frame, a first lead screw is rotationally connected to the middle of the testing frame, an output shaft of the moving motor is connected with the first lead screw, and a second lead screw is installed in the testing frame. The detection frame is slidably connected with an installation frame, the installation frame is in threaded connection with the first lead screw, an X-ray scanner is installed at the bottom of the installation frame, and a clamping assembly used for clamping and rotating the multiple layers of PCBs is arranged in the base. Through synchronous scanning and data fusion of an X-ray scanner and a visual scanner, the highlight saturation effect of a copper plating area in single plane imaging is avoided, geometrical characteristics of openings of through holes and blind holes are accurately recognized, copper plating interference signals are stripped, buried hole density characteristics are extracted, accurate classification and positioning of the blind holes and the buried holes are achieved, and finally the hole type misjudgment rate is reduced.

Description

Technical Field

[0001] This utility model relates to the field of non-destructive testing technology for printed circuit boards, and in particular to a testing device for multilayer blind and buried via PCB boards. Background Technology

[0002] As electronic devices evolve towards higher performance and miniaturization, multilayer printed circuit boards (PCBs) achieve high-density interconnections by stacking conductive and insulating layers, becoming the core carrier of modern electronic hardware. Interlayer electrical connections rely on metallized vias, where through-holes penetrate all layers to create full board conductivity, blind vias connect only outer layers to part of the inner layers with one end exposed on the board surface, and buried vias are completely hidden between inner layers. Blind and buried via technologies significantly improve wiring density and signal integrity, but their concealed structure also greatly increases the difficulty of manufacturing precision and quality inspection.

[0003] Currently, the industry primarily uses X-ray transmission imaging equipment for interlayer alignment detection. This technology uses X-rays to penetrate the PCB material and generates grayscale images based on the transmission differences between materials with different densities, such as copper and resin, thereby locating the positions of vias in each layer and determining axial alignment accuracy. However, the copper plating process fundamentally interferes with the detection: because copper has a much higher atomic number than the substrate, the copper-plated area appears extremely bright white under X-rays, while the resin substrate appears dark gray. When performing planar scanning on both sides of the PCB, the high brightness of the copper plating will cause serious misjudgments. Blind vias are weakly visible on non-drilled surfaces due to copper layer obscuring them, easily confused with buried vias; buried vias, due to the brightness halo caused by the multiple layers of copper, result in blurred via outlines and positioning errors.

[0004] When existing testing equipment is used, the high brightness of the copper-plated area in the X-ray image makes it impossible to reliably distinguish between blind vias and buried vias when scanning the front and back sides. It is also difficult to identify micron-level interlayer alignment errors. Traditional X-ray inspection has a high false alarm rate, which seriously restricts the product yield and reliability of high-density interconnect boards. Utility Model Content

[0005] To overcome the drawback of high brightness interference affecting the test results, this utility model provides a multi-layer blind and buried via PCB board testing device, aiming to solve the above-mentioned shortcomings.

[0006] A multilayer blind and buried via PCB board inspection device includes a base, an inspection frame connected to the top of the base, a moving motor installed inside the inspection frame, a first lead screw rotatably connected to the middle of the inspection frame, the output shaft of the moving motor connected to the first lead screw, a mounting frame slidably connected to the inspection frame, the mounting frame being threadedly connected to the first lead screw, an X-ray scanner installed at the bottom of the mounting frame, and a clamping assembly for clamping and rotating the multilayer PCB board provided inside the base.

[0007] As an improvement to the above solution, the clamping assembly includes a reversing motor, a fixed plate is rotatably connected to the middle of the base, the reversing motor is installed inside the base, the rotating shaft of the fixed plate is connected to the output shaft of the reversing motor, a bidirectional clamping cylinder is installed at the bottom of the fixed plate, and the piston rods on both sides of the bidirectional clamping cylinder are connected to clamping frames, the ends of the clamping frames pass through the fixed plate and are slidably connected to it.

[0008] As an improvement to the above solution, a limiting plate is slidably connected to the rear side of the fixed plate, and a second lead screw is rotatably connected to the middle of the limiting plate. The second lead screw is threadedly connected to the fixed plate, and the rear end of the second lead screw passes through the limiting plate and is connected to a handwheel.

[0009] As an improvement to the above solution, a shelf is connected to the front of the base.

[0010] As an improvement to the above solution, visual scanners are installed on the left and right sides of the mounting bracket.

[0011] As an improvement to the above solution, the shelf is provided with several adhesive strips, and the side of the clamp that contacts the PCB board is connected with adhesive strips.

[0012] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0013] 1. By simultaneously scanning and fusing data from X-ray scanners and vision scanners, the high-brightness saturation effect of copper plating areas in single-plane imaging is avoided, the geometric features of through holes and blind holes are accurately identified, copper plating interference signals are stripped away and buried hole density features are extracted, and the accurate classification and positioning of blind holes and buried holes are achieved, ultimately reducing the misclassification rate of hole types.

[0014] 2. The fixed plate is dynamically rotated by a commutator motor, which causes the fixed plate and the clamped PCB board to deflect continuously. The X-ray scanner obtains the interlayer penetration thickness difference data based on the tilt angle change and reconstructs the three-dimensional coordinates of the buried hole. The vision scanner calculates the axial depth of the blind hole through multi-view depth analysis, realizes the three-dimensional spatial alignment detection of the hole position between layers, and finally solves the problem of missed detection of axial misalignment in traditional single-plane scanning. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall structure of this utility model.

[0016] Figure 2 This is a three-dimensional structural diagram of the commutation motor and the bidirectional clamping cylinder of this utility model.

[0017] Figure 3 This is a three-dimensional structural diagram of the clamping frame, moving motor, and X-ray scanner of this utility model.

[0018] Figure 4This is a three-dimensional structural diagram of the limiting plate and the second lead screw of this utility model.

[0019] The following are the labels in the diagram: 1. Base, 2. Inspection frame, 3. Moving motor, 4. First lead screw, 5. X-ray scanner, 6. Mounting frame, 7. Fixing plate, 8. Two-way clamping cylinder, 9. Clamping frame, 10. Reversing motor, 11. Limiting plate, 12. Second lead screw, 13. Handwheel, 14. Placement plate, 15. Vision scanner, 16. Adhesive strip. Detailed Implementation

[0020] The above-described solution will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of this application. The implementation conditions used in the embodiments may be further adjusted according to the conditions of specific manufacturers, and the implementation conditions not specified are generally those in routine experiments.

[0021] Example: A multilayer blind / buried via PCB board inspection equipment, such as... Figures 1-4 As shown, the device includes a base 1, a detection frame 2, a moving motor 3, a first lead screw 4, an X-ray scanner 5, a mounting frame 6, and a clamping assembly. The detection frame 2 is connected to the top of the base 1. The moving motor 3 is installed inside the detection frame 2. The first lead screw 4 is rotatably connected to the middle of the detection frame 2. The output shaft of the moving motor 3 is coaxially connected to the first lead screw 4. The mounting frame 6 is slidably connected to the detection frame 2. The mounting frame 6 is threadedly connected to the first lead screw 4. The X-ray scanner 5 is installed at the bottom of the mounting frame 6, thus ensuring precise and controllable horizontal scanning trajectory and ensuring full X-ray coverage of the PCB board surface. The modular design improves the rigidity of the equipment and avoids vibration interference with imaging quality. The base 1 is equipped with a clamping assembly for clamping and rotating multi-layer PCB boards.

[0022] like Figures 1-4 As shown, the clamping assembly includes a fixed plate 7, a bidirectional clamping cylinder 8, a clamping frame 9, and a reversing motor 10. The fixed plate 7 is rotatably connected to the middle of the base 1, and the reversing motor 10 is installed inside the base 1. The rotating shaft of the fixed plate 7 is coaxially connected to the output shaft of the reversing motor 10. The bidirectional clamping cylinder 8 is installed at the bottom of the fixed plate 7. The piston rods on both sides of the bidirectional clamping cylinder 8 are connected to the clamping frame 9. The end of the clamping frame 9 passes through the guide groove of the fixed plate 7 and forms a sliding fit with the fixed plate 7. The pneumatic clamping force is uniform and adjustable to avoid deformation of the plate. The reversing motor 10 drives the rotation to achieve multi-angle scanning requirements.

[0023] like Figure 2 and Figure 4As shown, it also includes a limiting plate 11, a second lead screw 12, and a handwheel 13. The limiting plate 11 is slidably connected to the rear side of the fixed plate 7. The second lead screw 12 is rotatably connected to the middle of the limiting plate 11. The second lead screw 12 is threadedly connected to the fixed plate 7. The rear end of the second lead screw 12 passes through the limiting plate 11 and is connected to the handwheel 13. Round rods are connected to the left and right ends of the front side of the limiting plate 11. The round rods are inserted into the fixed plate 7 to ensure that the limiting plate 11 slides smoothly along the axial direction, allowing manual expansion of the support area to adapt to PCB boards of different sizes.

[0024] like Figure 1 As shown, it also includes a shelf 14. The shelf 14 is connected to the front of the base 1. The shelf 14 is used to store PCB boards in separate areas, thus optimizing the operation process.

[0025] like Figure 1 and Figure 3 As shown, it also includes a vision scanner 15. The vision scanner 15 is installed on the left and right sides of the mounting bracket 6. It synchronously acquires surface images with the X-ray scanner. The two sensors work together to solve the problem of hole position confusion caused by copper plating interference.

[0026] like Figures 1-4 As shown, it also includes adhesive strips 16. Several adhesive strips 16 are provided on the shelf 14. The side of the clamping frame 9 that contacts the PCB board is connected to the adhesive strips 16. A pressure sensor is installed in the adhesive strips 16 connected to the clamping frame 9. The pressure sensor is set with a clamping threshold. When the pressure reaches the pressure threshold, it means that the clamping is stable. The pressure sensing closed-loop control prevents overpressure damage.

[0027] After the staff places the multilayer PCB board on the fixing plate 7, the bidirectional clamping cylinder 8 drives the two clamping frames 9 on both sides to move synchronously towards the center. The adhesive strips 16 at the ends of the clamping frames 9 contact the edge of the board and apply clamping force. The pressure sensor built into the adhesive strip 16 monitors the pressure value in real time. When the pressure reaches the preset threshold, the controller is triggered to lock the clamping state, thus fixing the PCB board in the center. The X-ray scanner 5 and the vision scanner 15 start synchronously: the moving motor 3 drives the first lead screw 4 to rotate, which drives the mounting frame 6 and the fixed X-ray scanner 5 and vision scanner 15 to move back and forth in the horizontal direction to perform a full-coverage scan of the PCB board. The X-ray scanner 5 emits a cone beam of X-rays that penetrates each layer of the PCB and analyzes the location of buried holes based on the grayscale difference between the copper-plated area and the non-metallic area. The vision scanner 15 simultaneously acquires surface images and separates the opening positions of through holes and blind holes through feature recognition algorithms. The commutator motor 10 drives the fixed plate 7 to rotate at a set angle. After completing multi-view scanning, the computer performs difference operations on the full-angle data. The vision scanner 15 captures the morphology of the blind hole opening through multi-view imaging and calculates the blind hole depth by combining it with the penetration thickness data of the X-ray scanner 5. The X-ray scanner 5 determines the interlayer position of the buried hole based on the change in penetration thickness. The computer fuses the data to generate a three-dimensional hole alignment report. After the equipment completes the inspection, it automatically resets and releases the clamp.

[0028] When the width of the PCB board exceeds the size of the fixed plate 7, the handwheel 13 is turned to drive the second lead screw 12 to rotate. The threaded engagement between the second lead screw 12 and the fixed plate 7 converts the rotational motion into linear displacement, pushing the limiting plate 11 to slide backward along the guide groove of the fixed plate 7. The round rod on the front side of the limiting plate 11 forms a sliding pair constraint with the fixed plate 7, ensuring that the displacement trajectory is accurate and without deviation. After the limiting plate 11 moves backward to expand the support area, its front end works with the clamping frame 9 to form a positioning reference surface, keeping the ultra-wide PCB board centered during clamping. After adjustment, the bidirectional clamping cylinder 8 pushes the clamping frame 9 to press against both sides of the board, and the limiting plate 11 provides rear-end limiting support, eliminating the risk of board tilting.

[0029] The above embodiments are merely preferred embodiments of the present utility model and are not intended to limit the scope of the present utility model. Therefore, all equivalent changes made based on the content described in the claims of the present utility model should be included within the scope of the claims of the present utility model.

Claims

1. A multilayer blind / buried via PCB board inspection device, characterized in that, The device includes a base (1), a testing frame (2) connected to the top of the base (1), a moving motor (3) installed inside the testing frame (2), a first lead screw (4) rotatably connected in the middle of the testing frame (2), the output shaft of the moving motor (3) connected to the first lead screw (4), a mounting frame (6) slidably connected to the testing frame (2), the mounting frame (6) threadedly connected to the first lead screw (4), an X-ray scanner (5) installed at the bottom of the mounting frame (6), and a clamping assembly for clamping and rotating a multi-layer PCB board provided inside the base (1).

2. The multilayer blind / buried via PCB board inspection equipment as described in claim 1, characterized in that, The clamping assembly includes a reversing motor (10), a fixed plate (7) is rotatably connected in the middle of the base (1), the reversing motor (10) is installed in the base (1), the rotating shaft of the fixed plate (7) is connected to the output shaft of the reversing motor (10), a bidirectional clamping cylinder (8) is installed at the bottom of the fixed plate (7), the piston rods on both sides of the bidirectional clamping cylinder (8) are connected to clamping frames (9), and the end of the clamping frame (9) passes through the fixed plate (7) and is slidably connected to it.

3. The multilayer blind / buried via PCB board inspection equipment as described in claim 2, characterized in that, The fixed plate (7) is slidably connected to the limit plate (11) on the rear side. The limit plate (11) is rotatably connected to the middle of the second lead screw (12). The second lead screw (12) is threadedly connected to the fixed plate (7). The rear end of the second lead screw (12) passes through the limit plate (11) and is connected to a handwheel (13).

4. The multilayer blind / buried via PCB board inspection equipment as described in claim 3, characterized in that, The base (1) is connected to a shelf (14) at the front.

5. The multilayer blind / buried via PCB board inspection equipment as described in claim 1, characterized in that, Visual scanners (15) are installed on the left and right sides of the mounting bracket (6).

6. The multilayer blind / buried via PCB board inspection equipment as described in claim 4, characterized in that, The shelf (14) is provided with several adhesive strips (16), and the side of the clamp (9) that contacts the PCB board is connected with adhesive strips (16).

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