A device for water film test of a circuit board and a method thereof

Abstract

The application discloses a device and a method thereof for water film test of a circuit board, the device comprises a rack, an annular sliding table, an angle adjusting assembly, an energy supply assembly, a board placing support and an image taking assembly are arranged on the rack, a spraying assembly and a circulating water tank are arranged in the rack, the annular sliding table is arranged on the top plate of the rack, and a plurality of sliding blocks are arranged in the track of the annular sliding table. When the water film test of the circuit board is carried out, the circuit board can be adjusted to different inclination angles according to requirements, the energy supply assembly is used for supplying electric energy for the servo motor, the problem of cable winding is avoided when the cable is used for power supply during the angle adjustment, the cable for supplying power for the servo motor is not wound during the multiple and large-batch angle adjustment, the degree of automation is high, the high-resolution CMOS is used, the water film image on the surface of the circuit board can be transmitted to a control system, and whether the water film on the surface of the circuit board is broken or shrunk can be finely determined.

Description

Technical Field

[0001] This invention relates to the field of circuit board technology, and in particular to an apparatus and method for water film testing of circuit boards. Background Technology

[0002] The water film test for printed circuit boards (PCBs) is a rapid and intuitive method for testing the cleanliness and hydrophilicity of the copper surface during the manufacturing process, especially before wet processes such as outer layer pattern electroplating or chemical copper plating and nickel-gold plating. It is also known as the water breakage test or water film rupture test. Its principle utilizes the surface tension properties of water. When the copper surface of the PCB is very clean and hydrophilic, deionized water can spread evenly on its surface, forming a continuous, complete, and transparent water film. This water film typically needs to be maintained for a certain period, such as more than 15 seconds but less than 30 seconds. If there are contaminants or hydrophobic areas on the copper surface of the PCB, the surface tension of the deionized water will cause the water to shrink into droplets or the water film to rupture and shrink, leading to plating defects in subsequent wet processes.

[0003] The procedure for water film testing generally involves preparing deionized water at room temperature, immersing or spraying the circuit board, adjusting the board's tilt angle to between 30 and 45 degrees, and manually observing the water film state across the entire circuit board surface under good white light. Three patents with publication numbers CN218496760U, CN214373930U, and CN117890536A have solved the problem of contamination of both the deionized water and the circuit board during traditional manual handling of the circuit board and deionized water. However, with the development of circuit board technology and the increasing technical requirements for high-density circuit boards and large-scale water film testing, existing technical solutions are no longer sufficient. Currently, the observation of water film rupture and shrinkage is mainly done manually, which depends on the skill and experience of the inspector. The judgment of the results relies on human vision and experience, resulting in subjective differences. Furthermore, for large-area board observations, it is easy to miss small areas, such as the edges of holes in the circuit board, which has certain limitations. With the development of high-density and high-cost circuit boards, the traditional method of performing water film tests on multiple batches of circuit boards is no longer sufficient. The current requirement is to perform water film tests on every single circuit board to avoid affecting subsequent wet processing. Existing technologies cannot meet the technical requirements for large-scale water film testing. Furthermore, existing technologies cannot accommodate multi-angle adjustments of the circuit board tilt angle, and the low level of automation in current water film testing equipment leads to low detection efficiency. Therefore, there is an urgent need to design a water film testing device to solve these problems. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide an apparatus and method for water film testing of circuit boards.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] An apparatus for water film testing of circuit boards includes a frame on which an annular slide, an angle adjustment assembly, a power supply assembly, a board mounting bracket, and an image capturing assembly are mounted. A spray assembly and a circulating water tank are disposed within the frame.

[0007] The annular slide is mounted on the top plate of the frame. Multiple sliders are installed in the track of the annular slide. Each slider has an angle adjustment component and a plate support at its bottom. The angle adjustment component includes a base, a servo motor and a worm gear reducer from top to bottom. The angle adjustment component is used to adjust the tilt angle of the plate support. The annular slide drives the slider to move the plate support to the image acquisition component to capture the water film image.

[0008] The power supply component includes multiple transmitting coils disposed on the inner sidewall of the annular slide, receiving coils disposed on the sidewall of each slider, and a slip ring fixed on the output shaft of the servo motor. Each slider is also provided with a current collector module. The receiving coils transmit electrical energy to the current collector module. The current collector module is electrically connected to the input end of the slip ring, and the output end of the slip ring is electrically connected to the servo motor. The power supply component is used to provide electrical energy to the servo motor to drive the servo motor to rotate.

[0009] The image acquisition component includes a high-resolution CMOS, a light source, and an attitude adjustment mechanism. The high-resolution CMOS is used to capture images of the water film, the light source is used to illuminate the water film on the circuit board, and the attitude adjustment mechanism is used to adjust the angles of the high-resolution CMOS and the light source.

[0010] The spray assembly includes a bracket and several spray nozzles mounted on the bracket. The spray assembly is used to spray deionized water onto the surface of the circuit board.

[0011] The circulating water tank is used to hold deionized wastewater.

[0012] It also includes a control system and a water supply and circulation system. The control system is a PLC, and the water supply and circulation system is used to pump deionized water to the spray assembly and recycle deionized wastewater.

[0013] The annular slide is an electric slide, which is electrically connected to an external power supply. A control box is also installed inside the frame.

[0014] Each of the bases is fixedly connected to the corresponding slider with a pin. The top of the servo motor is fixedly connected to the bottom of the base. The output shaft of the servo motor is rigidly connected to the input end of the worm gear reducer. The output end of the worm gear reducer is rigidly connected to the plate support.

[0015] The transmitting coil is a DD-type copper winding coil, and a Hall sensor is provided on the side of each transmitting coil.

[0016] The slip ring is mounted on the output shaft of the servo motor. The stator of the slip ring is bolted to the housing of the servo motor, and the rotor of the slip ring is interference-fitted with the output shaft of the servo motor.

[0017] The attitude adjustment mechanism includes a vertical plate, a horizontal plate, a wedge block, an electric push rod, and a fixed plate. The vertical plate is set on the top plate of the frame, the horizontal plate is fixed perpendicularly to the vertical plate, the wedge block is set on the upper surface of the horizontal plate, the electric push rod is set on the inclined surface of the wedge block, the bottom of the fixed plate is hinged to the horizontal plate, the output shaft of the electric push rod is hinged to the upper part of the fixed plate, and the high-resolution CMOS and the light source are set on the fixed plate.

[0018] The fixed plate is equipped with a first tilt sensor and a laser rangefinder, and the output terminals of the first tilt sensor and the laser rangefinder are connected to the control system.

[0019] A second tilt sensor is installed at the bottom of the plate support, and the output end of the second tilt sensor is connected to the control system.

[0020] A visual positioning sensor is installed at the bottom of the horizontal plate. The output end of the visual positioning sensor is connected to the input end of the control system. The current collector module is a rectifier and voltage regulator circuit.

[0021] A method for water film testing of circuit boards, based on the above-described water film testing apparatus, includes the following steps:

[0022] S1. Place the circuit board to be tested for water film on the mounting bracket. The slider of the annular slide moves the circuit board on the annular slide. The transmitting coil and receiving coil generate electromagnetic induction and transmit electrical energy to the servo motor through the slip ring. The first tilt sensor transmits the tilt angle of the mounting bracket to the control system through the slip ring.

[0023] S2. The control system controls the servo motor to rotate, thereby causing the circuit board on the board mounting bracket to tilt. The tilt angle of the board mounting bracket can be adjusted according to requirements.

[0024] S3. The slider moves the circuit board until it is aligned with the high-resolution CMOS on the same horizontal axis. The visual positioning sensor acquires the circuit board image in real time and transmits it to the control system. The control system stops the slider. The second tilt sensor detects the tilt angle of the fixed plate and transmits it to the control system. The laser rangefinder measures the distance to the circuit board at a single point and transmits it to the control system. The control system controls the electric push rod to adjust the tilt angle of the high-resolution CMOS and the light source so that the high-resolution CMOS and the light source are always aligned with the circuit board and remain perpendicular to the circuit board.

[0025] S4. The nozzles in the spray assembly continuously and evenly spray deionized water onto the surface of the circuit board, forming a water film on the surface of the circuit board.

[0026] S5. The high-resolution CMOS sensor begins to capture images of the circuit board surface and transmits them to the control system. The control system starts timing, which lasts for 15-30 seconds. The operator observes the water film on the high-resolution screen of the control system to see if it shrinks or breaks.

[0027] S6. When conducting batch water film tests, repeat steps S1-S5.

[0028] The beneficial effects of this invention are:

[0029] This invention enables the circuit board to be adjusted to different tilt angles during water film testing, accommodating observation of water films on different types of circuit boards from various perspectives. A power supply component provides power to the servo motor, avoiding the cable tangling problem that often occurs when using cables for power supply during angle adjustment. Even with multiple large-scale angle adjustments, the power supply cable to the servo motor will not become tangled. The invention boasts a high degree of automation. Utilizing a high-resolution CMOS sensor, it can transmit the water film image of the circuit board surface to the control system, allowing for precise determination of whether the water film on the circuit board surface is broken or contracted. The attitude adjustment mechanism can adjust the angles of the high-resolution CMOS sensor and the light source, ensuring that both are always perpendicular to the circuit board surface, facilitating easier observation of the water film. This invention enables large-scale water film testing of circuit boards, improving the detection efficiency of water film testing. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of the present invention;

[0031] Figure 2 This is a schematic diagram of the structure of the annular slide table;

[0032] Figure 3 This is a schematic diagram of the angle adjustment component;

[0033] Figure 4 A schematic diagram of the image acquisition component;

[0034] Figure 5 A schematic diagram of the spray assembly and circulating water tank;

[0035] In the diagram, 1-frame, 2-ring slide, 3-plate support, 4-circulating water tank, 5-slider, 6-base, 7-servo motor, 8-worm gear reducer, 9-slip ring, 10-high resolution CMOS, 11-light source, 12-support, 13-spray nozzle, 14-vertical plate, 15-horizontal plate, 16-wedge block, 17-electric push rod, 18-fixed plate, 19-control box. Detailed Implementation

[0036] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings, but the scope of protection of the present invention is not limited to the following description.

[0037] like Figure 1-5 As shown, an apparatus for water film testing of circuit boards includes a frame 1, on which a ring slide 2, an angle adjustment assembly, a power supply assembly, a board mounting bracket 3, and an image capturing assembly are arranged. A spray assembly and a circulating water tank 4 are arranged inside the frame 1.

[0038] The annular slide 2 is installed on the top plate of the frame 1. Multiple sliders 5 are installed in the track of the annular slide 2. Each slider 5 has an angle adjustment component and a plate support 3 at its bottom. The angle adjustment component includes a base 6, a servo motor 7 and a worm gear reducer 8 from top to bottom. The angle adjustment component is used to adjust the tilt angle of the plate support 3. The annular slide 2 drives the sliders 5 to move the plate support 3 to the image acquisition component to capture the water film image.

[0039] The power supply component includes multiple transmitting coils disposed on the inner sidewall of the annular slide table 2, receiving coils disposed on the sidewall of each slider 5, and a slip ring 9 fixed on the output shaft of the servo motor 7. Each slider 5 is also provided with a current collector module. The receiving coil transmits electrical energy to the current collector module. The current collector module is electrically connected to the input end of the slip ring 9, and the output end of the slip ring 9 is electrically connected to the servo motor 7. The power supply component is used to provide electrical energy to the servo motor 7 to drive the servo motor 7 to rotate.

[0040] The image acquisition component includes a high-resolution CMOS 10, a light source 11, and an attitude adjustment mechanism. The high-resolution CMOS 10 is used to capture water film images, the light source 11 is used to illuminate the water film on the circuit board, and the attitude adjustment mechanism is used to adjust the angle between the high-resolution CMOS 10 and the light source 11.

[0041] The spray assembly includes a bracket 12 and a plurality of spray nozzles 13 disposed on the bracket 12. The spray assembly is used to spray deionized water onto the surface of the circuit board.

[0042] The circulating water tank 4 is used to hold deionized wastewater.

[0043] It also includes a control system and a water supply and circulation system. The control system is a PLC, and the water supply and circulation system is used to pump deionized water to the spray assembly and recycle deionized wastewater.

[0044] The annular slide 2 is an electric slide, which is electrically connected to an external power supply. A control box is also installed inside the frame.

[0045] Each of the bases 6 is fixedly connected to the corresponding slider 5 with a pin. The top of the servo motor 7 is fixedly connected to the bottom of the base 6. The output shaft of the servo motor 7 is rigidly connected to the input end of the worm gear reducer 8. The output end of the worm gear reducer 8 is rigidly connected to the plate support 3.

[0046] The transmitting coil is a DD-type copper winding coil, and a Hall sensor is provided on the side of each transmitting coil.

[0047] The slip ring 9 is mounted on the output shaft of the servo motor 7. The stator of the slip ring 9 is bolted to the housing of the servo motor 7, and the rotor of the slip ring 9 is interference-fitted with the output shaft of the servo motor 7.

[0048] The attitude adjustment mechanism includes a vertical plate 14, a horizontal plate 15, a wedge block 16, an electric push rod 17, and a fixed plate 18. The vertical plate 14 is mounted on the top plate of the frame 1. The horizontal plate 15 is vertically fixed to the vertical plate 14. The wedge block 16 is mounted on the upper surface of the horizontal plate 15. The electric push rod 17 is mounted on the inclined surface of the wedge block 16. The bottom of the fixed plate 18 is hinged to the horizontal plate 15. The output shaft of the electric push rod 17 is hinged to the upper part of the fixed plate 18. The high-resolution CMOS 10 and the light source 11 are mounted on the fixed plate.

[0049] The fixed plate 18 is equipped with a first tilt sensor and a laser rangefinder, and the output terminals of the first tilt sensor and the laser rangefinder are connected to the input terminal of the control system.

[0050] A second tilt sensor is provided at the bottom of the mounting plate bracket 3, and the output end of the second tilt sensor is connected to the input end of the control system.

[0051] A visual positioning sensor is provided at the bottom of the horizontal plate 15. The output end of the visual positioning sensor is connected to the input end of the control system. The current collector module is a rectifier and voltage regulator circuit.

[0052] A method for water film testing of circuit boards, based on the above-described water film testing apparatus, is characterized by comprising the following steps:

[0053] S1. Place the circuit board to be tested for water film on the board support. The slider of the circular slide table moves the circuit board on the circular slide table. The transmitting coil and receiving coil generate electromagnetic induction and transmit electrical energy to the servo motor through the slip ring. The first tilt sensor transmits the tilt angle of the board support to the control system through the slip ring.

[0054] S2. The control system controls the servo motor to rotate, thereby causing the circuit board on the board mounting bracket to tilt. The tilt angle of the board mounting bracket can be adjusted according to requirements.

[0055] S3. The slider moves the circuit board until it is on the same horizontal axis as the high-resolution CMOS. The visual positioning sensor acquires the circuit board image in real time and transmits it to the control system. The control system controls the slider to stop moving. The second tilt sensor detects the tilt angle of the fixed plate and transmits it to the control system. The laser rangefinder measures the distance to the circuit board at a single point and transmits it to the control system. The control system controls the electric push rod to adjust the tilt angle of the high-resolution CMOS and the light source so that the high-resolution CMOS and the light source are always aligned with the circuit board and remain perpendicular to the circuit board.

[0056] S4. The nozzles in the spray assembly continuously and evenly spray deionized water onto the surface of the circuit board, forming a water film on the surface of the circuit board.

[0057] S5. The high-resolution CMOS begins to capture images of the circuit board surface and transmits them to the control system. The control system starts timing, which lasts for 15-30 seconds. The operator observes the water film on the high-resolution screen of the control system to see if it shrinks or breaks.

[0058] S6. When conducting batch water film tests, repeat steps S1-S5.

[0059] This invention discloses a device for water film testing of circuit boards. A ring slide is mounted on a frame, and multiple transmitting coils are mounted on the side walls of the internal track of the ring slide. The transmitting coils are multi-segment transmitting coils, specifically DD-type copper winding coils, which have strong resistance to horizontal deviation. A receiving coil is mounted on the side wall of each slide, and multiple Hall sensors are mounted on the side walls of the transmitting coils. The Hall sensors detect the position of the slide and activate the transmitting coil closest to the slide. During the movement of the slide, the transmitting and receiving coils generate electromagnetic induction or magnetic resonance, thereby generating electrical energy. Each slide has a current collector module containing a rectifier and voltage regulator module. The electrical energy generated by the receiving coil is transmitted to a slip ring through the rectifier and voltage regulator module. The slip ring serves two purposes: transmitting electrical energy and transmitting signals. The electrical energy generated by the transmitting and receiving coils is delivered to a servo motor through the slip ring, providing power for the servo motor's operation. The encoder and second tilt sensor within the servo motor control the system, thereby enabling the circuit board to be placed on a mounting bracket and its tilt adjusted to the desired angle.

[0060] The slip ring not only transmits electrical energy and signals, but also plays another role in this invention by preventing cable tangling during the rotation of the servo motor, thus greatly improving the working efficiency of the invention. The control system in this invention is a PLC, integrated into a control box, which also features a high-resolution, high-frame-rate screen for human-machine interaction.

[0061] The control system of the present invention is also equipped with an image processing unit. The visual positioning sensor acquires images of the moving circuit board in real time and identifies the outline of the circuit board through an edge detection algorithm. When the deviation between the center of the circuit board outline and the preset coordinates is less than or equal to 0.1 mm, the visual sensor outputs a high-level positioning signal to the control system. The control system controls all the sliders of the annular slide to stop moving, that is, the center of the circuit board outline is on the same axis as the high-resolution CMOS and the light source.

[0062] This invention enables the circuit board to be adjusted to different tilt angles during water film testing, accommodating observation of water films on different types of circuit boards from various perspectives. A power supply component provides power to the servo motor, avoiding the cable tangling problem that often occurs when using cables for power supply during angle adjustment. Even with multiple large-scale angle adjustments, the power supply cable to the servo motor will not become tangled. The invention boasts a high degree of automation. Utilizing a high-resolution CMOS sensor, it can transmit the water film image of the circuit board surface to the control system, allowing for precise determination of whether the water film on the circuit board surface is broken or contracted. The attitude adjustment mechanism can adjust the angles of the high-resolution CMOS sensor and the light source, ensuring that both are always perpendicular to the circuit board surface, facilitating easier observation of the water film. This invention enables large-scale water film testing of circuit boards, improving the detection efficiency of water film testing.

Claims

1. An apparatus for water film testing of circuit boards, characterized in that: Includes a frame (1), on which are provided an annular slide (2), an angle adjustment component, a power supply component, a mounting plate bracket (3) and an image capturing component, and inside the frame (1) are provided a spray component and a circulating water tank (4). The annular slide (2) is set on the top plate of the frame (1). Multiple sliders (5) are set in the track of the annular slide (2). An angle adjustment component and a plate support (3) are set at the bottom of each slider (5). The angle adjustment component includes a base (6), a servo motor (7) and a worm gear reducer (8) from top to bottom. The angle adjustment component is used to adjust the tilt angle of the plate support (3). The annular slide (2) drives the slider (5) to move the plate support (3) to the image acquisition component to capture the water film image. The power supply component includes multiple transmitting coils disposed on the inner side wall of the annular slide (2), receiving coils disposed on the side wall of each slider (5), and a slip ring (9) fixed on the output shaft of the servo motor (7). Each slider (5) is also provided with a current collector module. The receiving coil transmits electrical energy to the current collector module. The current collector module is electrically connected to the input end of the slip ring (9). The output end of the slip ring (9) is electrically connected to the servo motor (7). The power supply component is used to provide electrical energy to the servo motor (7) to drive the servo motor (7) to rotate. The image acquisition component includes a high-resolution CMOS (10), a light source (11), and an attitude adjustment mechanism. The high-resolution CMOS (10) is used to capture water film images, the light source (11) is used to illuminate the water film on the circuit board, and the attitude adjustment mechanism is used to adjust the angle between the high-resolution CMOS (10) and the light source (11). The spray assembly includes a bracket (12) and a plurality of spray nozzles (13) disposed on the bracket (12). The spray assembly is used to spray deionized water onto the surface of the circuit board. The circulating water tank (4) is used to hold deionized wastewater; It also includes a control system and a water supply and circulation system. The control system is a PLC, and the water supply and circulation system is used to pump deionized water to the spray assembly and recycle deionized wastewater.

2. The apparatus for water film testing of circuit boards according to claim 1, characterized in that: The annular slide (2) is an electric slide, which is electrically connected to an external power supply. A control box (19) is also installed inside the frame (1).

3. The apparatus for water film testing of circuit boards according to claim 1, characterized in that: Each of the bases (6) is fixedly connected to the corresponding slider (5) by a pin. The top of the servo motor (7) is fixedly connected to the bottom of the base (6). The output shaft of the servo motor (7) is rigidly connected to the input end of the worm gear reducer (8). The output end of the worm gear reducer (8) is rigidly connected to the mounting plate bracket (3).

4. The apparatus for water film testing of circuit boards according to claim 1, characterized in that: The transmitting coil is a DD-type copper winding coil, and a Hall sensor is provided on the side of each transmitting coil.

5. The apparatus for water film testing of circuit boards according to claim 1, characterized in that: The slip ring (9) is mounted on the output shaft of the servo motor (7). The stator of the slip ring (9) is bolted to the housing of the servo motor (7), and the rotor of the slip ring (9) is interference-fitted with the output shaft of the servo motor (7).

6. The apparatus for water film testing of circuit boards according to claim 1, characterized in that: The attitude adjustment mechanism includes a vertical plate (14), a horizontal plate (15), a wedge block (16), an electric push rod (17), and a fixed plate (18). The vertical plate (14) is set on the top plate of the frame (1). The horizontal plate (15) is fixed vertically to the vertical plate (14). The wedge block (16) is set on the upper surface of the horizontal plate (15). The electric push rod (17) is set on the inclined surface of the wedge block (16). The bottom of the fixed plate (18) is hinged to the horizontal plate (15). The output shaft of the electric push rod (17) is hinged to the upper part of the fixed plate (18). The high-resolution CMOS (10) and the light source (11) are set on the fixed plate.

7. The apparatus for water film testing of circuit boards according to claim 6, characterized in that: The fixed plate (18) is equipped with a first tilt sensor and a laser rangefinder, and the output terminals of the first tilt sensor and the laser rangefinder are connected to the control system.

8. The apparatus for water film testing of circuit boards according to claim 1, characterized in that: The bottom of the mounting plate bracket (3) is provided with a second tilt sensor, and the output end of the second tilt sensor is connected to the control system.

9. The apparatus for water film testing of circuit boards according to claim 6, characterized in that: A visual positioning sensor is provided at the bottom of the horizontal plate (15). The output end of the visual positioning sensor is connected to the input end of the control system. The current collector module is a rectifier and voltage regulator circuit.

10. A method for water film testing of circuit boards, based on the apparatus for water film testing of circuit boards according to any one of claims 1-8, characterized in that: Includes the following steps: S1. Place the circuit board to be tested for water film on the board support. The slider of the circular slide table moves the circuit board on the circular slide table. The transmitting coil and receiving coil generate electromagnetic induction and transmit electrical energy to the servo motor through the slip ring. The first tilt sensor transmits the tilt angle of the board support to the control system through the slip ring. S2. The control system controls the servo motor to rotate, thereby causing the circuit board on the board mounting bracket to tilt. The tilt angle of the board mounting bracket can be adjusted according to requirements. S3. The slider moves the circuit board until it is on the same horizontal axis as the high-resolution CMOS. The visual positioning sensor collects the circuit board image in real time and transmits it to the control system. The control system controls the slider to stop moving. The second tilt sensor detects the tilt angle of the fixed plate and transmits it to the control system. The laser rangefinder measures the distance to the circuit board at a single point and transmits it to the control system. The control system controls the electric push rod to adjust the tilt angle of the high-resolution CMOS and the light source so that the high-resolution CMOS and the light source are always aligned with the circuit board and remain perpendicular to the circuit board. S4. The nozzles in the spray assembly continuously and evenly spray deionized water onto the surface of the circuit board, forming a water film on the surface of the circuit board. S5. The high-resolution CMOS begins to capture images of the circuit board surface and transmits them to the control system. The control system starts timing, which lasts for 15-30 seconds. The operator observes the water film on the high-resolution screen of the control system to see if it shrinks or breaks. S6. When conducting batch water film tests, repeat steps S1-S5.

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