CN102615425A - Processing system of laser special-shaped micropores based on refractive scanning system - Google Patents

Abstract

The invention discloses a laser special-shaped microhole processing system based on a refraction scanning system, including a high-beam quality laser output system, a focusing lens group, a beam scanning system, a focus adjustment mechanism, a workpiece adsorption positioning displacement system, and a computer control system. , which is characterized in that the beam scanning system is a refraction scanning system, which includes two parallel plates with the same thickness, which are parallel to each other and perpendicular to the laser light path, and are respectively installed on two vibrating mirror motors. The vibrating mirror motor drives the parallel plates to deflect and scan relative to the laser beam, so that the laser beam has a slight displacement relative to the original transmission optical path after passing through the two parallel plates. The displacement value is determined by the angle between the parallel plate and the transmission optical path. By changing the angle quickly through the refraction scanning system, it is possible to realize the microhole forming process of any shape on the workpiece by the laser beam.

Description

A processing system of laser special-shaped micro-holes based on refraction scanning system

technical field

The invention relates to a laser special-shaped microhole processing system and method based on a refraction scanning system, belonging to the application field of laser fine processing technology. the

Background technique

Laser micro-hole processing technology is to use the characteristics of the interaction between the laser beam and the material to carry out micro-drilling processing on materials (including metals and non-metals), involving multi-disciplinary comprehensive technologies such as optics, mechanics, electricity, computer control, material properties and detection. , It is widely used in high-tech industries such as automobiles, microelectronics, optical communications, aerospace, biomedicine, solar energy and fuel cell new energy, improving or replacing some traditional processing methods. At present, the semiconductor integrated circuit industry is developing rapidly in the world. Computers, mobile phone circuit boards, and portable consumer electronics products use high-density multilayer PCBs, which are compact in size and are developing towards miniaturization; the requirements for semiconductor chip production, testing, and packaging are constantly improving, and their structures are more compact. , The shape and volume continue to shrink. At present, the main applications of special-shaped micro-hole forming technology are: jet engine or gas turbine blade cooling hole, lubrication hole of powertrain components, textile spinneret, surface microstructure of various substrate materials, various special-shaped holes of automobile fuel injectors , chemical and biopharmaceutical filters, sieves, minimally invasive medical implants, solar cells, semiconductor lighting and other emerging industries. Depending on the application, these microwells have various track geometries, from cylinders to cones, grooves or specific shapes. Traditional processing methods such as mechanical drilling or punching can no longer meet the demand.

At present, there are three main types of laser microhole forming technologies: fixed beam pulse processing unit microholes, galvanometer scanning and precise helical drilling. 1. The microhole of the fixed beam pulse processing unit is completed by the fixed focal length laser focusing mirror and the moving workpiece, which provides high precision and high accuracy, and can obtain the minimum microhole diameter limited by the laser processing optical system. But this method can only process round holes, and if you want to get different microhole diameters, you can only achieve it by changing the focal length of the focusing lens. 2. The scanning and positioning speed of the galvanometer is fast. Due to the high-speed response of the galvanometer, it is more appropriate to drill a large number of array holes. Moreover, the size of the hole can be easily controlled by software to walk out of various pre-set trajectories, so various special-shaped holes can be processed, such as square holes, triangular holes, star-shaped holes, etc., but due to the angle of the vibrating mirror motor The problem of resolution and temperature drift, not only the contour is not good, but also high repeatability cannot be obtained during micro-hole machining, so it lacks high positioning accuracy in a large local small area, and it is not suitable to use this method when the diameter of the small hole is less than 250 microns plan. 3. Precise helical drilling means through various

Optical components make the laser processing beam deviate from the center of the small hole, and then rotated by a high-speed motor to minimize the thermal effect on the edge of the small hole. The size of the hole and the taper of the hole can be controlled by software, and the through hole and blind hole can be realized. Processing, but only round holes can be processed, and special-shaped holes cannot be processed like galvanometer scanning.

Contents of the invention

In order to overcome the shortcomings of the existing laser microhole forming technology, the present invention provides a laser special-shaped microhole processing system based on a refraction scanning system.

（图1），根据光学折射定律（snell定律）和三角函数公式推导： The basic principle of the present invention: the parallel plate is an optical element with a certain thickness D formed by two refraction planes parallel to each other. It is an afocal device, which will not enlarge or reduce the object, and has no contribution to the optical power in the system. ; The exit direction of the incident light remains unchanged after passing through the parallel plate, but there will be a displacement L relative to the optical axis. Assuming that the refractive index of the parallel plate is n, its angle relative to the optical axis of the laser beam is

(Figure 1), according to the law of optical refraction (snell's law) and trigonometric function formula derivation:

,可得

,Available

F:

get:

的不同而不同。在实际应用中，平行平板被安装于振镜电机上，替代了原来的反射镜片，平行平板的入光面和出光面均镀有对应激光波长的增透膜，以减少激光束在这两个面上的反射损耗，激光束经平行平板折射传输。振镜电机带动平行平板相对入射光线快速偏转扫描，偏转角决定了光线的轴向位移值。两个平行平板相对入射光线偏转扫描方向互相垂直，因而在工件表面上可以组合出任意形状的激光加工轨迹。 It can be seen that the beam displacement L varies with the angle between the parallel plate and the optical axis of the laser beam

different from each other. In practical application, the parallel flat plate is installed on the oscillating mirror motor to replace the original reflector. The light incident surface and the light exit surface of the parallel flat plate are coated with anti-reflection coatings corresponding to the laser wavelength to reduce the laser beam in the two The reflection loss on the surface, the laser beam is refracted and transmitted through the parallel plate. The vibrating mirror motor drives the parallel plate to deflect and scan quickly relative to the incident light, and the deflection angle determines the axial displacement value of the light. The deflection and scanning directions of the two parallel plates relative to the incident light are perpendicular to each other, so laser processing tracks of arbitrary shapes can be combined on the surface of the workpiece.

Based on the above basic principles, the technical solution of the present invention is a laser special-shaped micro-hole processing system based on a refraction scanning system, including a high-beam quality laser output system, a focusing lens group, and a beam scanning system.

System, focusing mechanism, workpiece adsorption positioning displacement system and computer control system, characterized in that the beam scanning system is a refraction scanning system, which includes two parallel flat plates, two vibrating mirror motors and corresponding control modules , the two parallel plates have the same thickness, and the light-incident surface and the light-emitting surface are coated with anti-reflection coatings corresponding to the laser wavelength. The two galvanometer motors drive the parallel plates to deflect and scan quickly relative to the incident beam. Vertical, their combined movement makes the laser beam walk out of the processing track of any shape on the surface of the workpiece. Through the control module of the galvanometer motor, the two parallel plates are controlled to quickly deflect and scan the optical axis of the incident beam according to the special-shaped micro-hole laser processing track.

The high-beam-quality laser output system includes lasers, beam expanders and laser transmission systems, adopts all-solid-state pulsed lasers that output nanosecond or shorter pulse widths, and uses computers to control laser switching signals and adjust the output power and repetition rate of lasers. The frequency is transmitted to the focusing lens group through the beam expander and the laser transmission system.

The focusing lens group is to make the laser beam spot on the workpiece reach or approach the diffraction limit after being focused by the focusing lens group, and make the working distance as long as possible to accommodate the refraction type in the optical path between the laser focusing lens group and the workpiece. scan system.

The focusing mechanism, the focusing lens group and the refraction scanning system are adjusted as a whole by the focusing mechanism to adjust the distance between them and the workpiece, so that the processing surface is located on the focal plane of the laser focusing lens group.

The workpiece adsorption positioning displacement system includes a workpiece installation mechanism and a two-dimensional displacement platform. The installation mechanism has the function of positioning and registration, and makes the surface of the workpiece level and smooth; the center position of the micro-hole processing is determined by a high-precision two-dimensional It is realized by a three-dimensional working displacement platform, and its positioning accuracy and repeat positioning accuracy are better than 5 microns.

The computer control system includes a hardware system and a software system. A motion control card is installed in the computer system to synchronously control the laser switch, adjust the output power and repetition frequency of the laser, and control the deflection scanning of the parallel flat plate in two perpendicular directions relative to the incident optical axis. , laser focusing and movement and positioning registration of the two-dimensional work displacement platform, the computer software system mainly includes:

(1) Laser control module: control laser switch, adjust laser output power and repetition frequency and other working parameters;

(2) Galvanometer scanning control module: control the galvanometer motor to drive the parallel plate to deflect and scan in two perpendicular directions relative to the laser optical axis;

(3) Focusing module: control the focusing mechanism to adjust the distance between the laser focusing lens group and the workpiece to ensure that the processing surface is located on the focal plane of the laser focusing lens group;

(4) Displacement control module: Control the fixed-point movement of the high-precision two-dimensional working displacement platform, and realize the determination of the center point position of the microhole array.

The beneficial effect of the present invention is that it not only retains the advantages of high scanning and positioning speed of the galvanometer, simple and convenient control of the processing track, and can realize the advantages of processing various special-shaped holes; The processing range of millimeters is accurately reduced to hundreds of microns. This hundred-fold optical miniaturization system greatly reduces the impact of angular resolution, thermal drift, and zero-point drift of high-speed galvanometer motors, thus ensuring high precision in laser processing. positioning and repeatability.

Description of drawings

Figure 1 is a schematic diagram of parallel plate refraction;

Fig. 2 is a functional block diagram of the system of the present invention;

Fig. 3 is a schematic structural diagram of a refraction scanning system.

Detailed ways

The laser used in the present invention adopts DPSS laser, that is, a semiconductor-pumped solid-state laser. As shown in Figure 2 and Figure 3, the DPSS laser 1 outputs a controlled high repetition rate ultrashort pulse laser, which is expanded and collimated by a beam expander 2 and passed through The light path conduction and reflection 3 enter the focusing lens group 4, and the parallel light converges near the surface of the workpiece 20 through the focusing lens group 4; two parallel plates 15a, 15b with the same thickness are placed in parallel and perpendicular to the optical axis of the incident light, and they are respectively installed On the two galvanometer motors 16a, 16b, the galvanometer motors 16a, 16b drive the parallel plates 15a, 15b to quickly deflect and scan relative to the incident laser beam. The deflection scan directions of the two parallel plates 15a, 15b are perpendicular to each other, and their combined motion is A machining track of any shape is produced on the surface of the workpiece. Parallel plates 15a, 15b and vibrating mirror motors 16a, 16b form the refraction scanning system 10, the refraction scanning system 10 and the focusing lens group 4 adjust the distance between them and the workpiece through the focusing mechanism 5, so that the parallel laser beams Focusing near the processing surface forms a fine, high-energy-density focal spot, which melts or vaporizes the workpiece 20 at an instant high temperature. The vibrating mirror control module 7 controls the deflection scanning movement of the refraction scanning system. The workpiece 20 is installed on the high-precision two-dimensional displacement platform 6, and the center position of the microhole is determined by the movement of the displacement platform 6.

Example

Using high beam quality DPSS laser, the wavelength is 1.06 microns, the average power output is 10W, and the repetition rate

The rate is 40KHz, and the pulse width is 8ns. The output beam is expanded by 5 times, the focal length of the focusing lens group is 100mm, and the diameter of the focusing spot is less than 10 microns. Ordinary optical glass is used to make parallel plates with a refractive index of 1.5 and a thickness of 2.6 mm. When the scanning optical deflection angle of the galvanometer motor is ±12 ⁰ , the translational deflection of the laser beam is 0.185mm, that is to say, through such a refraction scanning system, the laser beam can scan and process any shape in the range of 370μm×370μm. microporous.

Claims (6)

1. A laser special-shaped microhole processing system based on a refraction scanning system, including a high-beam quality laser output system, a focusing lens group, a beam scanning system, a focusing mechanism, a workpiece adsorption positioning displacement system, and a computer control system. It is characterized in that the beam scanning system is a refraction scanning system, which includes two parallel plates, two vibrating mirror motors and corresponding control modules, the two parallel plates have the same thickness, and the light incident surface and the light exit surface are coated There is an anti-reflection film corresponding to the laser wavelength, and the two galvanometer motors drive the parallel flat plate to deflect and scan quickly relative to the incident beam. The deflection and scanning directions of the two parallel flat plates are perpendicular to each other. Their combined movement makes the laser beam walk out of the processing track of any shape on the surface of the workpiece. , through the control module of the vibrating mirror motor, the two parallel plates are controlled to quickly deflect and scan the optical axis of the incident beam according to the laser processing track of the special-shaped microhole. 2. the processing system based on the laser special-shaped microhole of refraction scanning system according to claim 1, is characterized in that, described high beam quality laser output system, comprises laser device, beam expander and laser transmission system, adopts output nano An all-solid-state pulsed laser with a pulse width of 2 seconds or less, using a computer to control the laser switch signal and adjust the output power and repetition frequency of the laser, and transmit it to the focusing lens group through the beam expander and the laser transmission system. 3. The laser special-shaped microhole processing system based on the refraction scanning system according to claim 1, wherein the focusing lens group is to make the laser parallel beam focused by the focusing lens group so that the light spot on the workpiece reaches Or close to the diffraction limit, and make the working distance as long as possible to accommodate the refraction scanning system in the optical path between the laser focusing lens group and the workpiece. 4. The processing system based on the laser special-shaped micro-hole of the refraction scanning system according to claim 1, wherein the focusing mechanism, the focusing lens group and the refraction scanning system are adjusted and processed by the focusing mechanism as a whole The distance between the workpieces makes the processing surface on the focal plane of the laser focusing lens group. 5. The laser special-shaped microhole processing system based on the refraction scanning system according to claim 1, wherein the workpiece adsorption positioning displacement system includes a workpiece mounting mechanism and a two-dimensional displacement platform, and the mounting mechanism has Positioning and registration functions, and make the surface of the workpiece level and flat; the center position of the micro-hole machining is realized by a high-precision two-dimensional work displacement platform, and its positioning accuracy and repeat positioning accuracy are better than 5 microns. 6. The processing system of a kind of laser special-shaped microhole based on the refraction scanning system according to claim 1, wherein the computer control system includes a hardware system and a software system, and a motion control card is installed in the computer system, Synchronously control the laser switch, laser output power and repetition frequency adjustment, control the deflection scanning of the parallel plate in two perpendicular directions relative to the incident optical axis, laser focusing, and the movement and positioning of the two-dimensional working displacement platform. The computer The software system mainly includes: (1) Laser control module: control laser switch, adjust laser output power and repetition frequency working parameters; (2) Galvanometer scanning control module: control the galvanometer motor to drive the parallel plate to deflect and scan in two perpendicular directions relative to the laser optical axis; (3) Focusing module: control the focusing mechanism to adjust the distance between the laser focusing lens group and the workpiece to ensure that the processing surface is located on the focal plane of the laser focusing lens group; (4) Displacement control module: Control the fixed-point movement of the high-precision two-dimensional working displacement platform, and realize the determination of the center point position of the microhole array.

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