Laser scanning imaging device of PCB laser direct writing forming equipment

Abstract

A laser scanning imaging device of PCB laser direct writing forming equipment comprises a laser generating and processing unit used for generating single-mode laser and emitting the single-mode laser to a first light beam needed by PCB direct imaging after collimation and focusing; a first galvanometer assembly; the first galvanometer assembly comprises a first galvanometer and a first rotating shaft for driving the first galvanometer to rotate, and is used for deflecting the laser incident at a set angle back and forth and emitting a first light beam; the second galvanometer assembly comprises a second galvanometer and a second rotating shaft used for driving the second galvanometer to rotate, the second galvanometer assembly is used for reflecting the first light beam, and the first light beam forms a one-dimensional image on the second galvanometer; and a rotating surface formed when the first rotating shaft rotates is perpendicular to a rotating surface formed when the second rotating shaft rotates. The utility model has the advantages that the image grid precision can be improved, and the gradient of the line edge after exposure can be improved.

Description

Technical Field

[0001] This utility model belongs to the technical field of PCB laser direct writing imaging, and particularly relates to a laser scanning imaging device for PCB laser direct writing forming equipment. Background Technology

[0002] There are various design schemes for PCB laser direct writing imaging devices. Currently, the mainstream approach is to project the PCB circuit image onto a PCB board coated with dry film using a DMD digital lens. The DMD digital lens has 2-megapixel units, and the parallel light input can be controlled to reflect the image at the focal plane. To ensure image accuracy while increasing production capacity in PCB laser direct writing equipment, DMD tilted grayscale exposure technology is commonly used. Based on the linear absorption of light energy by the dry film, a tilted scanning method is used to create different exposures (grayscale exposures) on the dry film, achieving small grid precision under large spot size and high production capacity. Therefore, the DMD tilt factor is constantly being improved. However, due to phenomena such as light diffraction, the minimum grid precision is greater than 3, meaning a minimum grid precision of 1.22µm under 405nm laser. Since the DMD working principle requires a PCB linewidth of at least 50µm, the grid precision achieved by the DMD tilted grayscale exposure technology can meet the requirements. However, at the line edges, because the grayscale is generated by grid resolution, the exposure at the line edges on the dry film exhibits a relatively small slope. Utility Model Content

[0003] To address the aforementioned technical problems, this utility model proposes a laser scanning imaging device for PCB laser direct writing forming equipment, the specific technical solution of which is as follows:

[0004] A laser scanning imaging device for a PCB laser direct writing forming equipment includes:

[0005] The laser generation and processing unit is used to generate a single-mode laser and, after collimation and focusing, emit the first beam required for direct imaging of the PCB.

[0006] First galvanometer assembly; the first galvanometer assembly includes a first galvanometer and a first rotation axis for driving the first galvanometer to rotate, for deflecting the laser beam incident at a set angle back and forth and emitting a first beam;

[0007] The second galvanometer assembly includes a second galvanometer and a second rotation axis for driving the second galvanometer to rotate, for reflecting the first beam, the first beam forming a one-dimensional image on the second galvanometer.

[0008] The rotational plane formed when the first rotating shaft rotates and the rotational plane formed when the second rotating shaft rotates are perpendicular to each other.

[0009] Furthermore, the laser generation processing unit includes:

[0010] A collimating lens is set at a predetermined distance from the single-mode laser.

[0011] A focusing lens is used to capture and focus the beam of a single-mode laser after it has passed through a collimating lens.

[0012] A reflector is used to rotate the beam of light focused by a focusing lens to a set angle.

[0013] Furthermore, the single-mode laser is generated and emitted by the single-mode laser, which is a single-mode laser module or a single-mode laser diode.

[0014] Furthermore, the first galvanometer is a MEMS galvanometer.

[0015] Furthermore, the resonant scanning operating frequency of the mems galvanometer ranges from 0.5K to 20KHz.

[0016] Furthermore, the second galvanometer is an audio galvanometer.

[0017] Furthermore, the resonant scanning frequency of the audio galvanometer is 2-3 orders of magnitude lower than the resonant scanning operating frequency of the mems galvanometer.

[0018] Furthermore, the device also includes a drive controller, wherein the first and second rotating axes and the controlled end of the single-mode laser that generates single-mode laser are respectively connected to the control pins corresponding to the drive controller, and the drive controller interacts with external information through a communication interface.

[0019] Furthermore, it also includes a protective objective lens for transmitting the light beam reflected by the second galvanometer onto the exposure focal plane.

[0020] Furthermore, the wavelength of the single-mode laser is 405nm.

[0021] The advantages of this utility model are:

[0022] (1) In this application, after single-mode laser collimation and focusing, the energy of the Gaussian spot is more concentrated and the nonlinear absorption of light energy by the exposed dry film can form an exposure point smaller than the Gaussian spot, thereby improving the grid accuracy of the image. Since the light intensity energy at the center of the Gaussian spot is high and its penetration on the dry film is strong, the single-mode laser requires a short working time, making the exposure of the upper and lower surfaces of the exposed dry film more consistent, which can improve the slope of the image edge after exposure and development.

[0023] (2) This application utilizes a Mens galvanometer and an audio galvanometer, and the first and second rotating axes are perpendicular to each other, which can realize the exposure of two-dimensional images on the exposure focal plane while improving the laser energy utilization rate, thereby increasing production capacity.

[0024] (3) The single-mode laser of this application uses a single-mode laser diode, which can make the device compact in size and control. Attached Figure Description

[0025] Appendix Figure 1 This is an optical path structure diagram of a PCB laser direct writing imaging device using a two-dimensional scanning method according to this utility model.

[0026] Appendix Figure 2 This is a schematic diagram of the drive control of a PCB laser direct writing imaging device using a two-dimensional scanning method according to this utility model.

[0027] In the picture:

[0028] 1. Single-mode laser; 2. Collimating lens; 3. Focusing lens; 4. Reflecting mirror; 5. Audio galvanometer; 6. MEMS galvanometer; 7. Protective objective lens; 8. Exposure focal plane; 9. Drive controller. Detailed Implementation

[0029] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. In the description of the embodiments of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0030] Definitions:

[0031] Audio galvanometer: An optical lens device capable of rapidly changing its reflection angle according to the changing patterns of audio signals. Simply put, it acts like a flexible "mirror," oscillating rapidly based on sound-related electrical signals to alter the optical path. Its core components typically include a freely rotating lens and a drive mechanism (such as a motor or electromagnetic drive) to propel this lens. When an audio signal is input, it undergoes appropriate circuitry to convert the signal's characteristics (such as frequency and amplitude variations) into control signals recognizable by the drive mechanism. The drive mechanism then uses these signals to rapidly adjust the lens's angle according to corresponding patterns. For example, high-frequency audio frequencies might correspond to rapid, small-amplitude oscillations of the lens, while low-frequency frequencies might correspond to slower but larger-amplitude oscillations.

[0032] MEMS galvanometers are miniature, drivable mirrors fabricated using Micro-Electro-Mechanical System (MEMS) technology. A MEMS galvanometer primarily consists of a movable micromirror structure and corresponding driving elements. Its working principle involves applying an electrical signal to the driving element, causing it to deform or exert force, thereby deflecting or vibrating the micromirror structure and altering the optical path. For example, electrostatically driven MEMS galvanometers utilize electrostatic attraction to displace the mirror; electromagnetically driven ones use electromagnetic force to rotate the mirror.

[0033] The working principle of a two-dimensional scanning PCB laser direct writing imaging device is to use the collimated and focused Gaussian light of the laser to be projected onto the focal plane after passing through two orthogonal galvanometers. The laser beam with variable intensity is used to directly expose and write any designed pattern on the photoresist, thereby directly transferring the design pattern onto the mask.

[0034] Specifically, the device mainly consists of a computer control system, a laser source, a two-dimensional scanning platform, an optical system, and photoresist. During operation, the computer control system, based on pre-designed graphic data, controls the two-dimensional scanning platform to move the photoresist in a horizontal two-dimensional scanning motion. Simultaneously, the laser beam emitted from the laser source, after modulation and focusing by the optical system, illuminates the photoresist, causing a photochemical reaction and forming a latent image on the photoresist that matches the designed pattern. Finally, through processes such as development and etching, the latent image is converted into the actual circuit pattern.

[0035] Currently, the exposure machine, as a PCB laser direct-write imaging device, includes a laser and a two-dimensional scanning platform.

[0036] One common application of 2D scanning platforms is the use of DMDs (Digital Micromirror Devices) or rotating mirrors. A DMD consists of an array of numerous tiny, rotatable mirrors. These micromirrors can rapidly change angles under electrical signal control, thus modulating light. For example, when light needs to pass through a specific area for exposure, the corresponding micromirror rotates to the appropriate angle to reflect the light onto the designated optical path; when no light is needed, the micromirror rotates to another angle, causing the light to be reflected and absorbed elsewhere. Through this rapid and precise control, the exposure pattern can be scanned and exposed on a 2D plane with a set pixel-level precision, accurately constructing the desired exposure image. Rotating mirrors are typically driven at high speed by motors or other drive devices. The mirror surface reflects incident light. During rotation, the light changes its reflection direction as the mirror angle changes, thus achieving scanning at different positions on the 2D plane. Correspondingly, DMDs use multimode lasers shaped into rectangular planar light (DMDs are composed of small mirrors and are mainly used in projectors), while rotating mirrors mostly use lasers output from high-power laser generators.

[0037] To improve image grid accuracy, the slope of line edges after exposure is increased, such as... Figure 1 As shown, this application discloses a laser scanning imaging device for a PCB laser direct writing forming equipment, comprising:

[0038] The laser generation and processing unit is used to generate a single-mode laser and, after collimation and focusing, emit the first beam required for direct imaging of the PCB.

[0039] First galvanometer assembly; the first galvanometer assembly includes a first galvanometer and a first rotation axis for driving the first galvanometer to rotate, for deflecting the first beam incident at a set angle back and forth and emitting a second beam.

[0040] The second galvanometer assembly includes a second galvanometer and a second rotation axis for driving the second galvanometer to rotate, for reflecting the second light beam, the second light beam forming a one-dimensional image on the second galvanometer;

[0041] The rotational plane formed when the first rotating shaft rotates and the rotational plane formed when the second rotating shaft rotates are perpendicular to each other.

[0042] Based on this scheme, the first rotation axis is parallel to the vertical axis of the exposure focal plane 8, and the second rotation axis is parallel to the horizontal axis of the exposure focal plane 8. The purpose of rotating the first rotation axis is to change the exposure position of the light beam on the vertical axis of the exposure focal plane 8, and the purpose of rotating the second rotation axis is to change the exposure position of the light beam on the horizontal axis of the exposure focal plane 8. This application ensures that the first galvanometer in the first galvanometer assembly and the second galvanometer assembly in the second galvanometer assembly are orthogonal, so that the scanned image is projected onto the exposure focal plane 8.

[0043] This application utilizes a single-mode laser whose energy intensity gradually decreases from the center to the outer edge, exhibiting a Gaussian energy distribution curve. It boasts high beam quality, a small beam diameter, and a small divergence angle, resulting in excellent focusing characteristics, a small focused spot, and strong mode stability. When the single-mode laser is collimated and focused, it presents a Gaussian spot on the focal plane. The light intensity and energy are greatest at the center of the spot. As the distance *r* from the center maximum increases, the light energy decreases with a Gaussian function: I = I*exp(-a·r^2), where *a* is a scaling factor. The larger the scaling factor *a*, the more concentrated the energy of the Gaussian spot. By utilizing the nonlinear absorption of light energy by the dry film, an exposure point smaller than the Gaussian spot can be formed, improving the grid accuracy of the image.

[0044] Because the light intensity and energy at the center of the Gaussian spot are high, it has strong penetrating power on the dry film. Therefore, the single-mode laser requires a short working time, which makes the exposure of the upper and lower surfaces of the dry film more uniform and can improve the slope of the image edges after exposure and development.

[0045] Specifically, the laser generation and processing unit includes:

[0046] Collimating lens 2 is set at a predetermined distance from the single-mode laser.

[0047] The focusing lens 3 is used to acquire and focus the beam of the single-mode laser after it passes through the collimating lens 2;

[0048] The reflector 4 is used to rotate the beam focused by the focusing lens 3 to a set angle.

[0049] In one embodiment, the distance between the collimating lens 2 and the single-mode laser is determined based on simulation data.

[0050] In one embodiment, the reflector 4 rotates the first beam focused by the focusing lens 3 by 90° and incidents it at a set angle onto the first galvanometer in the first galvanometer assembly. In this scheme, the set angle ranges from 10 to 60°, and can be 20°, 30°, 45°, 50°, 55°, or 60°. This angle setting facilitates the installation of the device in the equipment and increases the beam spot size on the mirror surface to protect the mirror surface.

[0051] In one embodiment, the single-mode laser is generated and emitted by the single-mode laser 1. The single-mode laser 1 is a single-mode laser diode, or it can be connected to the collimating lens 2 via a single-mode fiber structure. When the single-mode laser 1 is a single-mode laser diode, the device size and control can be made more compact.

[0052] In one embodiment, the wavelength of the single-mode laser 1 is 405 nm.

[0053] In one embodiment, the first galvanometer is a MEMS galvanometer 6. The MEMS galvanometer 6 is a small, drivable reflector 4 fabricated based on microelectromechanical systems (MEMS) technology, which operates stably in a resonant state. The MEMS galvanometer 6 can effectively reduce the duty cycle of the single-mode laser 1, thereby improving the utilization rate of laser energy and increasing production capacity.

[0054] In one embodiment, the resonant scanning operating frequency of the MEMS galvanometer 6 ranges from 0.5KHz to 20KHz. Therefore, the configuration of the MEMS galvanometer 6 can improve the scanning speed, and also improve the scanning speed of the exposed image.

[0055] In one embodiment, the second galvanometer is an audio galvanometer 5.

[0056] In one embodiment, the resonant scanning frequency of the audio galvanometer 5 is 2-3 orders of magnitude lower than the resonant scanning operating frequency of the MEMS galvanometer 6. This setup combines the advantages of the rapid scanning of the MEMS galvanometer 6. First, a one-dimensional image is formed in the direction of the MEMS galvanometer 6. Then, after the audio galvanometer 5 moves a distance equal to the diameter of a light spot along the vertical axis of the exposure focal plane 8, the MEMS galvanometer 6 scans rapidly again to form a one-dimensional image. Through multiple movements along the vertical axis, a complete two-dimensional image scan is formed.

[0057] In one embodiment, the resonant scanning frequency of the audio mirror 5 is 1 Hz.

[0058] In one embodiment, the device further includes a drive controller 9, wherein the first and second rotating axes are respectively connected to control pins corresponding to the drive controller 9.

[0059] In one embodiment, the apparatus further includes a drive controller 9 connected to the controlled end of the single-mode laser 1 that generates single-mode laser light.

[0060] like Figure 2 As shown, in one embodiment, the device further includes a drive controller 9, wherein the first and second rotating axes and the controlled end of the single-mode laser 1 that generates single-mode laser are respectively connected to the control pins corresponding to the drive controller 9, and the drive controller 9 interacts with external information through a communication interface.

[0061] In one embodiment, the device further includes a protective objective lens 7, used to encapsulate the first galvanometer, the second galvanometer, and the reflector 4 during the installation of the optical path to the mechanical structure, keeping the internal space clean. During the installation of the optical path to the mechanical structure, the first galvanometer, the second galvanometer, and the reflector 4 need to be installed in a cavity, that is, the lens barrel and the protective objective lens are on the light-emitting surface of the cavity, making the cavity a sealed and clean space, which can protect each optical element.

[0062] The working principle of this device is as follows:

[0063] After the drive controller 9 is powered on, it checks the status of the MEMS mirror 6 and the audio mirror 5. It starts the MEMS mirror 6 to operate at the resonant frequency point and the corresponding required optical angle, and deflects the audio mirror 5 to the intermediate state angle. The drive controller 9 receives image data through the communication interface and converts the image data into control data. After starting image scanning, the drive controller 9 first operates the audio mirror 5 and deflects its mirror surface to the starting angle of the vertical axis scanning. Then, according to the working status of the MEMS mirror 6 and the data of the horizontal axis of the scanned image, it sends a control to the single-mode laser diode to output the pulse light of the one-dimensional image. Then, it scans the ablation segment and controls the audio mirror 5 to deflect by an increment angle, so that the light spot moves a distance of about one spot diameter in the vertical axis of the exposure focal plane 8. Then, according to the working status of the MEMS mirror 6, it controls the single-mode laser diode to output the pulse light of the one-dimensional image and controls the audio mirror 5 to deflect by an increment angle until the two-dimensional scanning of the image is completed.

[0064] It should be noted that the software part of the drive controller 9 described in this application is not within the scope of protection of this application. This application provides hardware structure support for the laser scanning imaging device of PCB laser direct writing equipment.

[0065] In this specification, references to terms such as "some embodiments" or "examples" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. The illustrative expressions of the above terms in this specification do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0066] The above are merely preferred embodiments of this utility model and do not constitute any limitation on this utility model. Any equivalent substitutions or modifications made by those skilled in the art to the technical solutions and contents disclosed in this utility model without departing from the scope of the technical solutions of this utility model shall still fall within the protection scope of this utility model.

Claims

1. A laser scanning imaging device for a PCB laser direct writing forming equipment, characterized in that, include: The laser generation and processing unit is used to generate a single-mode laser and, after collimation and focusing, emit the first beam required for direct imaging of the PCB. First galvanometer assembly; the first galvanometer assembly includes a first galvanometer and a first rotation axis for driving the first galvanometer to rotate, for deflecting the laser beam incident at a set angle back and forth and emitting a first beam; The second galvanometer assembly includes a second galvanometer and a second rotation axis for driving the second galvanometer to rotate, for reflecting the first beam, the first beam forming a one-dimensional image on the second galvanometer. The rotational plane formed when the first rotating shaft rotates and the rotational plane formed when the second rotating shaft rotates are perpendicular to each other.

2. The laser scanning imaging apparatus for a PCB laser direct writing forming equipment according to claim 1, characterized in that, The laser generation and processing unit includes: A collimating lens is set at a predetermined distance from the single-mode laser. A focusing lens is used to capture and focus the beam of a single-mode laser after it has passed through a collimating lens. A reflector is used to rotate the beam of light focused by a focusing lens to a set angle.

3. The laser scanning imaging apparatus for a PCB laser direct writing forming equipment according to claim 1, characterized in that, The single-mode laser is generated and emitted by a single-mode laser, which is either a single-mode laser module or a single-mode laser diode.

4. The laser scanning imaging apparatus for a PCB laser direct writing forming equipment according to claim 1, characterized in that, The first galvanometer is a MEMS galvanometer.

5. The laser scanning imaging apparatus for a PCB laser direct writing forming equipment according to claim 4, characterized in that, The resonant scanning operating frequency range of the MEMS galvanometer is 0.5K to 20KHz.

6. The laser scanning imaging apparatus for a PCB laser direct writing forming equipment according to claim 1, 4, or 5, characterized in that, The second galvanometer is an audio galvanometer.

7. The laser scanning imaging apparatus for a PCB laser direct writing forming equipment according to claim 6, characterized in that, The resonant scanning frequency of the audio galvanometer is 2-3 orders of magnitude lower than the resonant scanning operating frequency of the MEMS galvanometer.

8. The laser scanning imaging apparatus for a PCB laser direct writing forming equipment according to claim 1, characterized in that, The device also includes a drive controller, wherein the first and second rotating axes and the controlled end of the single-mode laser that generates single-mode laser are respectively connected to the control pins corresponding to the drive controller, and the drive controller interacts with external information through a communication interface.

9. The laser scanning imaging apparatus for a PCB laser direct writing forming equipment according to claim 1, characterized in that, It also includes a protective objective lens for transmitting the light beam reflected by the second galvanometer onto the exposure focal plane.

10. The laser scanning imaging apparatus for a PCB laser direct writing forming equipment according to claim 1, characterized in that, The wavelength of the single-mode laser is 405nm.

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