A high-speed drilling method and equipment for ceramic materials

Abstract

The present invention provides a method and equipment for high-speed drilling of ceramic materials, using time-shaped millisecond pulsed lasers for efficient and high-quality micro-hole processing of ceramic materials. Specifically, by adjusting the control of the laser, the output millisecond laser has a specific pulse waveform with a high peak power front edge and low peak power middle and trailing edges; the millisecond laser first passes through a collimating mirror to have the ability of low divergence and long-distance transmission, then its deflection is controlled by a galvanometer scanner, and finally it is focused by a focusing mirror and acts on a specified position on the upper surface of the sample; the high peak power front edge of the millisecond laser generates defects when acting on the sample, and these defects will significantly increase the absorption of the subsequent millisecond laser by the ceramic material, so that the subsequent low peak power middle and trailing edges can form the required micro-hole processing under enhanced absorption, reducing the thermal effect of millisecond laser processing, thereby controlling the micro-hole diameter, thermal defects, etc., and realizing high-efficiency and high-quality micro-hole processing of ceramic materials.

Description

Technical Field

[0001] The present invention relates to the field of laser processing. Specifically, it relates to a method and equipment for high-speed drilling of ceramic materials. Background Art

[0002] Ceramics have the characteristics of high hardness, thermal conductivity, resistivity, and thermal stability, small dielectric constant, and a coefficient of thermal expansion matching that of chips. They are the first choice for a new generation of microelectronic devices and systems and have become the main material for circuit boards in fields such as aerospace, 5G communication, high-power power semiconductors, and high-power LED lighting, with broad application prospects. However, as a typical hard and brittle material, traditional mechanical processing of ceramics easily leads to substrate fracture, and there are also great limitations in special processing methods. With the technological maturity and widespread application of industrial lasers, laser processing, as a new type of green technology that is non-contact and non-abrasive, has high precision, high efficiency, and process controllability, making it a new choice for processing ceramic circuit boards.

[0003] In existing research, the rapid development of nanosecond, picosecond, and femtosecond lasers has demonstrated significant quality advantages in micro- and nano-fabrication. However, the current situation of low processing efficiency, insufficient stability, and high equipment costs makes it difficult to meet the industrial processing requirements of ceramic substrates. Millisecond lasers with high pulse energy have high material removal efficiency, but the processing is accompanied by obvious thermal effects, and the sputtering removal of molten ceramics is insufficient. Microholes are often accompanied by defects such as large pore diameters, large tapers, and microcracks. Therefore, how to achieve high-efficiency and high-quality microhole processing of ceramic materials has become an urgent problem to be solved.

[0004] Ceramic materials have extremely low absorption of laser light. For example, the absorption of alumina ceramics for near-infrared laser light is generally less than 5%. Therefore, traditional millisecond lasers often require extremely high peak power densities to form a certain ablation effect on the surface of ceramic materials during microhole processing. However, there is a phenomenon of sudden increase in absorption rate throughout the entire cycle of such high-peak-power-density millisecond laser drilling: after a defective small hole is formed on the initial surface ablated by the millisecond laser, the subsequent high-peak-power pulsed laser injected will be effectively absorbed under the multiple reflections of the smooth inner wall of the small hole. Small holes of appropriate depth can even increase the absorption of millisecond laser light to saturation (similar to a black hole small hole). Therefore, in the later stage of millisecond laser processing of ceramic microholes, the absorption increase will significantly increase the materials heated, melted, and vaporized by the millisecond laser, resulting in an enlarged microhole diameter and increased thermal defects (such as cracks, recast layer thickness, microhole taper, etc.), making it difficult to meet actual requirements.

[0005] In view of the above problems, this patent proposes a high-speed drilling method and equipment for a new type of ceramic material, specifically using time-shaped millisecond pulsed lasers for micro-hole processing of ceramic materials. The time-shaped millisecond laser has a high peak power front edge and low peak power middle and trailing edges. The high peak power front edge is fully utilized to create defects on the ceramic material, which will significantly increase the absorption of the ceramic material for subsequent millisecond lasers. As a result, the subsequent low peak power middle and trailing edges can form the required micro-hole processing under enhanced absorption, reducing the thermal effect of millisecond laser processing, thereby controlling the micro-hole diameter, thermal defects, etc. Summary of the Invention

[0006] A high-speed drilling method and equipment for a new type of ceramic material provided by the present invention includes the following steps:

[0007] Step 1: By adjusting the control of the laser, make the output millisecond laser have a specific pulse waveform with a high peak power front edge and low peak power middle and trailing edges;

[0008] Step 2: The laser passes through a collimating mirror to have the ability of low divergence and long-distance transmission, and then its deflection is controlled by a galvanometer mirror. After being focused by a focusing mirror, it acts on a specified position on the upper surface of the sample;

[0009] Step 3: The high peak power front edge of the millisecond pulsed laser acts on the sample to generate defects. The defects will significantly increase the absorption of the sample for subsequent millisecond lasers. Therefore, the low peak power middle and trailing edges can achieve the required micro-hole processing, effectively reducing the thermal effect during the processing, and finally realizing high-efficiency and high-quality micro-hole processing of ceramic materials.

[0010] Furthermore, the wavelength of the millisecond laser is in the range of 266 - 2000 nm.

[0011] Furthermore, the methods for adjusting the millisecond laser pulse waveform include, but are not limited to, controlling the waveform of the input excitation of the laser.

[0012] Furthermore, the peak power of the front edge of the millisecond laser pulse is more than 3 times that of the peak power of the middle and trailing edges.

[0013] Furthermore, the pulse width of the front edge of the millisecond laser pulse is 50 μs - 1 ms, and the peak power is 3 kW - 15 kW. The pulse width of the middle and trailing edges of the millisecond laser pulse is 100 μs - 10 ms, and the peak power is 1 kW - 3 kW.

[0014] Furthermore, the diameter of the defect is 5 μm - 100 μm, the depth is 1 μm - 20 μm, and the shape is conical, flat-top type, etc. The defect can increase the material absorption by more than 5 times.

[0015] Furthermore, the sample is made of materials such as alumina, aluminum nitride, silicon nitride, etc.

[0016] Further, the thickness of the sample is 0.2 mm - 5 mm.

[0017] Further, after the galvanometer adjusts the laser direction, the laser is made to vertically incident on the surface of the sample, and the processing path of the laser on the sample is controlled by the movement of the galvanometer.

[0018] Further, the sample is fixed by a fixture and a stage, and its upper surface is located at the laser focus position.

[0019] Beneficial effects

[0020] The present invention mainly has the following technical advantages:

[0021] 1. By forming a specific pulse waveform (with a high peak power front edge, a low peak power middle edge, and a trailing edge), the problem of the change in absorption rate during the millisecond laser drilling process of ceramic materials is solved. The pulse front edge is fully utilized to prepare defects on the ceramic surface to enhance laser absorption, thereby reducing the overall injected laser energy, reducing the thermal effect of millisecond laser processing, and thus controlling the micropore diameter, thermal defects, etc., and improving the quality of the micropores.

[0022] 2. Since the defects greatly improve the absorption of subsequent lasers, through a suitable waveform, the required through holes can be formed under the action of a single pulse, and it can be applied to high-speed moving and scanning drilling, thereby improving the processing efficiency. Description of the drawings

[0023] Figure 1 It is the output timing diagram of the millisecond laser of the ceramic material high-speed drilling method and equipment provided by the present invention, showing a typical laser waveform with a high peak power front edge and a low peak power middle edge and a trailing edge.

[0024] Specifically, the peak power of the pulse front edge is much greater than the peak power of the pulse middle edge and the trailing edge (more than 3 times), and the width of the pulse front edge is much smaller than the width of the pulse middle edge and the trailing edge, so as to meet the requirements of creating defects by the pulse front edge and stably absorbing by the pulse middle edge and the trailing edge.

[0025] Figure 2 It is the schematic diagram of the technical solution of the ceramic material high-speed drilling method and equipment provided by the present invention.

[0026]

Description of the reference numerals

[0027] 1. Time-shaped millisecond laser; 2. Collimating mirror; 3. Galvanometer; 4. Focusing mirror; 5. Laser focus; 6. Ceramic material. Specific embodiments

[0028] To make the technical problems, technical solutions, and advantages to be solved by the present invention clearer, the following will be described in detail with reference to the accompanying drawings and specific embodiments. It should be noted here that the descriptions of these embodiments are used to help understand the present invention, but do not constitute a limitation to the present invention.

[0029] Example 1

[0030] Select an alumina ceramic sheet with a size of 30mm×30mm×1mm as the sample. Control the millisecond laser output of the millisecond laser with a high peak power front edge and low peak power middle and trailing edges waveform. The laser wavelength is 1030nm, and the repetition frequency is 100Hz. Among them, the peak power of the pulse front edge is 15kW, the front edge width is 1ms, the peak power of the pulse middle and trailing edges is 5kW, and the middle and trailing edge widths are 3ms.

[0031] After passing through the collimating mirror 2, the laser has the ability of low divergence and long-distance transmission. After the galvanometer 3 controls the laser deflection, it is focused by the focusing mirror 4 and then acts on the specified position 5 on the upper surface of the sample 6. The high peak power front edge of the millisecond pulsed laser generates defects after acting on the sample, and these defects significantly increase the absorption of the sample to the subsequent millisecond laser. Therefore, the low peak power middle and trailing edges can achieve the required micro-hole processing, and the thermal effect is effectively reduced.

[0032] This embodiment uses single-pulse scanning drilling. Each pulse directly processes a micro-hole. By moving the galvanometer to control the laser to continuously process micro-holes on the sample, high-efficiency and high-quality micro-hole processing is finally achieved.

[0033] Example 2

[0034] Select a silicon nitride ceramic sheet with a size of 20mm×10mm×2mm as the sample. Control the millisecond laser output of the millisecond laser with a high peak power front edge and low peak power middle and trailing edges waveform. The laser wavelength is 1080nm, and the repetition frequency is 20Hz. Among them, the peak power of the pulse front edge is 12kW, the front edge width is 500μs, the peak power of the pulse middle and trailing edges is 3kW, and the middle and trailing edge widths are 4ms.

[0035] After passing through the collimating mirror 2, the laser has the ability of low divergence and long-distance transmission. After the galvanometer 3 controls the laser deflection, it is focused by the focusing mirror 4 and then acts on the specified position 5 on the upper surface of the sample 6. In this embodiment, one micro-hole is processed under the action of every 5 laser pulses. Similarly, by moving the galvanometer to control the processing path of the laser, high-efficiency and high-quality micro-hole processing is achieved.

[0036] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A high-speed drilling method for ceramic materials, characterized in that, Including: Step 1: By adjusting the control of the laser, the output millisecond laser has a specific pulse waveform with a high peak power front edge and low peak power middle and trailing edges. The pulse width of the front edge of the millisecond laser pulse is 50 μs - 1 ms, and the peak power is 3 kW - 15 kW. The pulse width of the middle and trailing edges of the millisecond laser pulse is 100 μs - 10 ms, and the peak power is 1 kW - 3 kW. Step 2: The laser passes through a collimating mirror to have the ability of low divergence and long-distance transmission, and then its deflection is controlled by a galvanometer. After being focused by a focusing mirror, it acts on a specified position on the upper surface of the sample. Step 3: The high peak power front edge of the millisecond pulsed laser generates defects when acting on the sample. The defects will significantly increase the absorption of the sample for the subsequent millisecond laser. Therefore, the low peak power middle and trailing edges can achieve the required micro-hole processing, effectively reducing the thermal effect during the processing. Since the defects greatly improve the absorption of the subsequent laser, the required through-hole can be formed under the action of a single pulse, which is applied to high-speed moving and scanning punching to improve the processing efficiency, and finally achieve high-efficiency and high-quality micro-hole processing of ceramic materials.

2. The high-speed drilling method for ceramic materials according to claim 1, wherein The wavelength of the millisecond laser is in the range of 266 - 2000 nm.

3. The high-speed hole punching method for ceramic materials according to claim 1, characterized in that, The methods for adjusting the millisecond laser pulse waveform include but are not limited to controlling the waveform of the input excitation of the laser.

4. The high-speed hole punching method for ceramic materials according to claim 1, characterized in that, The peak power of the front edge of the millisecond laser pulse is more than 3 times that of the middle and trailing edges.

5. The high-speed hole punching method for ceramic materials according to claim 1, characterized in that The diameter of the defect is 5 μm - 100 μm, the depth is 1 μm - 20 μm, the shape is conical or flat-top, and the defect increases the material absorption by more than 5 times.

6. The high-speed drilling method for ceramic materials according to claim 1, characterized in that, The sample is alumina or aluminum nitride or silicon nitride.

7. The high-speed hole punching method for ceramic materials according to claim 1, characterized in that, The thickness of the sample is 0.2 mm - 5 mm.

8. The high-speed hole punching method for ceramic materials according to claim 1, characterized in that, After the galvanometer adjusts the laser direction, it makes the laser perpendicularly incident on the surface of the sample, and controls the processing path of the laser on the sample by moving the galvanometer.

9. The high-speed hole punching method for ceramic materials according to claim 1, characterized in that, The sample is fixed by a fixture and a stage, and its upper surface is located at the laser focus position.

Images