A high-quality laser drilling method for ceramic materials based on a sandwich structure

Abstract

The present invention relates to the application field of laser micro-nano processing, and provides a high-quality laser drilling method for ceramic materials based on a sandwich structure. The method specifically includes: using a fixture to closely contact and fix three layers (first layer, middle layer, lower layer) of ceramics to form a sandwich structure, and coating the upper surface of the upper layer so that it can effectively absorb laser energy; the laser is focused on the coating-treated surface, and the through-hole processing of the three layers of ceramics is achieved at one time by ablation; the first layer and the lower layer have a large number of recast layers and closed pores due to contact with the air free surface, while the through-hole quality of the middle layer ceramics is not affected by air and is effectively guaranteed; the middle layer ceramics are selected as the final through-hole processing sample to obtain a ceramic micro-hole processing result with a smaller diameter, smaller taper, less recast layer, and no closed pores; in addition, by adjusting the thickness of the first layer and the lower layer of ceramics, micro-holes with a diameter smaller than the laser spot can be obtained, and the taper of the micro-holes can be actively adjusted.

Description

Technical Field

[0001] The present invention relates to the field of continuous laser processing applications, and particularly to a method for high-quality laser processing of micro-holes. Background Art

[0002] Ceramics are mainly divided into structural ceramics and functional ceramics, and have a wide range of applications in various fields. Structural ceramics mainly utilize the mechanical, thermal, and some chemical functional properties of ceramics, and the main components include silicon carbide, alumina, zirconia, etc.; while functional ceramics mainly utilize the non-mechanical properties of ceramics, and there are many types, including dielectric ceramics, semiconductor ceramics, and optical ceramics, etc. Their performance is stable, the price is low, and they can be easily integrated. When structural ceramics are applied in engineering, such ceramics are also called engineering ceramics. Engineering ceramics have excellent properties under high-temperature conditions, including high strength, high hardness, corrosion resistance, wear resistance, good oxidation resistance, ablation resistance, etc. These excellent properties make them widely used in military, communication, chemical equipment, medicine and other fields. Alumina ceramics are a leading variety that has attracted much attention in engineering ceramics. Its strong insulation, stable chemical properties, high strength, good thermal conductivity and other characteristics give it unique advantages in mechanical, thermal, electrical and other aspects. Because of its wide range of raw materials, it is widely used in the electronics industry, especially as a circuit board material. Alumina ceramics are also widely used in high-power power semiconductor devices, 5G communication, high-power LED lighting, and aerospace and other fields.

[0003] With the wide application of alumina ceramic materials, their processing has become a new challenge due to their high hardness, brittleness, and low toughness. Traditional processing methods face problems of high cost and low efficiency. In contrast, laser processing has many advantages, such as high brightness, monochromaticity, good directivity, and precise control of the processing process. At the same time, laser processing is also easier to automate and has lower losses. Therefore, laser processing has incomparable advantages in processing alumina ceramic materials. However, in the application of punching holes in alumina ceramics, due to the small single-pulse energy of picosecond and femtosecond ultrafast lasers, only micro-holes with extremely small diameters can be processed, and it is necessary to punch holes by means of rotary cutting to meet the hole diameters required by actual industrial needs. The punching efficiency is low, the equipment cost is high, and it is difficult to meet the actual industrial production needs; nanosecond lasers face the plasma shielding effect in the punching processing of alumina ceramics, resulting in a reduction in laser energy utilization rate and poor processing effects. To overcome this problem, it is usually necessary to adopt rotary cutting processing or process in an auxiliary liquid environment, which increases the processing complexity, reduces the efficiency and affects the processing quality, etc., making it difficult to efficiently realize and obtain high-quality through-holes for the laser punching method of alumina ceramics. Therefore, how to efficiently process high-quality alumina ceramic through-holes to meet the needs of actual production and life has become a new problem and challenge.

[0004] The present invention forms a sandwich structure by using a fixture to closely contact and fix multiple layers of ceramics (the first layer, the middle layer, and the lower layer). By coating the upper surface of the first-layer material to enable it to effectively absorb laser energy, the laser directly acts on the surface of the first-layer material and realizes through-hole processing of multiple layers of ceramics at one time. There are a large number of recast layers on the first layer and the lower layer due to contact with air, and there is also the phenomenon of closed pores. However, the quality of the through-holes in the middle-layer ceramics is not affected by air and is effectively guaranteed. Using the middle-layer ceramics as the final through-hole processing sample, a ceramic micro-hole processing result with a smaller diameter, a smaller taper, fewer recast layers, and no closed pores can be obtained. At the same time, by adjusting the thicknesses of the first layer and the lower layer of ceramics, micro-holes with a diameter smaller than the laser spot can be obtained, and the taper of the micro-holes can be actively adjusted. This method improves the efficiency and quality of laser processing of ceramic micro-holes, and can effectively control the micro-holes at the same time. Summary of the Invention

[0005] In view of the above problems, the present invention provides a high-quality laser drilling method for ceramic materials based on a sandwich structure. A coating is applied to the surface of the ceramic material to promote its absorption of laser energy, so that the laser acts efficiently on the material surface. Several same or different materials are closely contacted and fixed to each other by a fixture to form a sandwich structure material. The first layer is a ceramic material coated with a coating, and the other materials are not coated with a coating. The sandwich structure material is fixed and the laser is guided to ablate the upper surface of the first-layer material of the sandwich structure material. Through-hole processing of multiple layers of ceramics is realized at one time by laser ablation. Since both the first layer and the lower layer materials are in contact with air, there are closed pore phenomena and a large number of recast layers in both layers of samples. However, the middle-layer ceramics are not affected by air and are effectively guaranteed. Using the middle-layer ceramics as the final processing sample, a ceramic micro-hole processing structure with a smaller diameter, a smaller taper, fewer recast layers, and no closed pores can be obtained. At the same time, by adjusting the thicknesses of the first layer and the lower layer of ceramics, micro-holes with a diameter smaller than the laser spot can be obtained, thereby improving the efficiency of laser processing of ceramic micro-holes and realizing effective control of high-quality micro-hole processing of ceramic materials.

[0006] To achieve the above object, a high-quality laser drilling method for ceramic materials based on a sandwich structure provided by the present invention includes the following steps:

[0007] (1) Use a fixture to closely contact and fix 3 layers (the first layer, the middle layer, and the lower layer) of ceramics to form a sandwich structure, and perform coating treatment on the upper surface of the upper layer to enable it to effectively absorb laser energy.

[0008] (2) The laser is focused on the coated surface, and through-hole processing of 3 layers of ceramics is realized at one time by ablation. There are a large number of recast layers and closed pore phenomena on the first layer and the lower layer due to contact with the free surface of air, while the quality of the through-holes in the middle-layer ceramics is not affected by air and is effectively guaranteed.

[0009] (3) Select the middle-layer ceramic as the final sample for through-hole machining to obtain ceramic micro-holes with smaller diameter, smaller taper, less recast layer, and no closed holes. In addition, by adjusting the thicknesses of the first-layer and bottom-layer ceramics, micro-holes with diameters smaller than the laser spot can be obtained, and the taper of the micro-holes can be actively adjusted.

[0010] Furthermore, the coating is a black dye or other coatings that can enhance energy absorption, aiming to enhance the energy absorption of the multi-layer material.

[0011] Furthermore, the sandwich structure is made of the same or different materials in close contact with each other, and there should be no other foreign substances between each layer of materials.

[0012] Furthermore, the thicknesses of the upper layer and the bottom layer can be selected according to the actual situation (50 μm - 5 mm), and the middle layer can also be selected according to the actual situation (25 μm - 5 mm).

[0013] Furthermore, the fixture can be a simple fixture such as tape, aiming to make the multi-layer material in close contact and fixed, and not affecting the laser acting on the material.

[0014] Furthermore, the ceramic material can be materials such as fused quartz, silicon, and alumina.

[0015] Furthermore, the laser is a continuous laser, a millisecond laser, or a nanosecond laser.

[0016] Furthermore, the high-quality laser-drilled sample is taken from the middle layer, and it is not limited to the middle layer of the 3-layer sample (i.e., not only limited to the second layer).

[0017] Generally speaking, compared with the prior art solutions through the above technical solutions of the present invention, the following main advantages are presented:

[0018] 1. In the past, when laser machining ceramic materials, the material surface was coated with a coating and directly laser machined. The micro-holes produced not only had a relatively thick recast layer but also had a large taper, making it difficult to be widely used in production and daily life. Through the multi-layer stacking method of the present invention, the molten ceramic generated by ablation and melting of the upper layer assists in laser machining the ceramic material of this layer to produce high-quality micro-holes. At the same time, the contact with air during sample machining is avoided. The micro-holes produced have a relatively thin recast layer and almost no taper, being suitable for wide application in production and daily life.

[0019] 2. Laser processing drills holes in ceramics by ablation. When processing thicker alumina ceramic materials, the ablation holes produced have obvious pore diameter changes on the upper surface, while the holes in the middle area have certain production and processing application significance. At this time, the holes in the middle area cannot be processed and used alone, lacking convenience. In the present invention, multiple thinner ceramic materials are closely contacted and fixed together by a fixture to make them have a certain thickness. Through laser processing, holes (high-quality micro-holes) in the middle area can be directly obtained for production and processing applications, providing convenience for sampling in laser processing.

[0020] 3. In addition, when the existing laser is used for micro-hole processing, the obtained micro-hole diameter is generally larger than the laser spot, it is difficult to obtain a micro-hole diameter smaller than the spot, and it is difficult to actively control the micro-hole taper. By reasonably setting the thickness of the first-layer sample in the sandwich structure, the multiple reflections of the processed micro-hole wall in the first layer can be fully utilized, making the laser spot deposited on the middle-layer sample smaller than the incident laser spot size, thereby obtaining micro-holes with a diameter smaller than the incident spot size; at the same time, by reasonably setting the thickness of the first-layer and lower-layer samples in the sandwich structure, the taper of the micro-holes can also be actively controlled.

[0021] The present invention effectively improves the laser processing micro-hole efficiency and micro-hole quality of ceramic materials, having significant technical advantages. Description of the Drawings

[0022] Figure 1 It is a system diagram of the laser processing multi-layer ceramic material of the present invention.

[0023] Figure 2 It is a schematic structural diagram of the sandwich structure (multi-layer material) of the present invention.

[0024] Figure 3 It is a SEM comparison diagram of the micro-holes of the single-layer ceramic material and the micro-holes of the middle-layer ceramic material of the multi-layer material of the present invention. Among them, (a) is the overall SEM diagram of the single-layer ceramic material; (b) is the SEM diagram of the middle-layer ceramic material of the multi-layer material; (c) is the enlarged SEM diagram of area I; (d) is the enlarged SEM diagram of area II.

[0025] Figure 4 It is a SEM diagram of the micro-hole processing of the middle-layer ceramic material of the multi-layer material in Example 4 of the present invention.

[0026] Description of the reference numerals: 1 - laser; 2 - control system; 3 - beam expander; 4 - reflector; 5 - focusing lens; 6 - sandwich structure material (multi-layer material); 7 - three-dimensional motion platform; 8 - first-layer ceramic material (coated with coating); 9 - middle-layer ceramic material; 10 - lower-layer ceramic material. Detailed Embodiments

[0027] 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 description of these embodiments is used to help understand the present invention, but does not constitute a limitation on the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0028] Aiming at the problems that it is difficult to obtain high-quality micro-holes in ceramic materials with high efficiency by the existing laser processing micro-hole methods, the present invention provides a high-quality laser drilling method for ceramic materials based on a sandwich structure.

[0029] The structure of an example provided by the present invention is shown in the figure, and it is composed of a laser 1, a control system 2, a three-dimensional motion platform 7, a beam expander 3, a reflector 4, a focusing lens 5 and a sandwich structure material (multi-layer material) 6.

[0030] In this embodiment, the laser 1, the beam expander 3, the reflector 4, the focusing lens 5 and the multi-layer material 6 are on the same optical path. The control system 2 is respectively connected to the laser 1 and the three-dimensional motion platform 7 for controlling their operations.

[0031] The laser 1 is usually a continuous laser, a millisecond laser or a nanosecond laser. Before processing, the upper surface of the first layer material 8 of the multi-layer material is coated with a coating to improve the efficiency of laser processing. After fixing the multi-layer material 6 on the fixture of the three-dimensional motion platform 7, the three-dimensional motion platform 7 is controlled to focus the laser on the surface of the first layer 8 of the multi-layer material. Then the laser is turned on to realize multi-layer laser processing of micro-holes in the multi-layer material 6 at one time. After processing, the multi-layer material 6 is taken off and the intermediate layer is taken out, thus obtaining high-quality micro-holes in ceramic materials.

[0032] Specific example:

[0033] Example 1: Taking an alumina ceramic material of 30mm×30mm×1mm as an example, 3 layers of 1mm alumina ceramics are closely contacted and fixed by using a fixture to form a Figure 2 sandwich structure (multi-layer structure) as shown. The upper surface of the upper layer material is soaked and smeared with diluted black pigment so that it can effectively absorb laser energy. The multi-layer material is fixed on the three-dimensional motion platform, and the three-dimensional motion platform is controlled to focus the millisecond laser on the upper surface of the upper layer material through the focusing lens. The parameters of the millisecond laser are adjusted: the power is 700W, the duty cycle is 10%, the repetition frequency is 100Hz, and the processing time is 50ms. The millisecond laser is turned on to realize through-hole processing of 3 layers of alumina ceramics by ablation at one time. After processing, the laser is turned off and the multi-layer material is taken off. The intermediate layer alumina ceramic material is taken as the target sample, and high-quality micro-hole results with an upper hole diameter of 51μm, a middle part of 47μm, a lower part of 43μm, and a recast layer thickness of 25μm are obtained. Its morphology is asFigure 3 as shown in (b) and (d).

[0034] Example 2: In this example, an alumina ceramic material with a size of 30 mm × 30 mm × 1 mm is taken as an example. Using a fixture, three layers of 1-mm alumina ceramics are closely contacted and fixed to form a sandwich structure (multi-layer structure) as shown in Figure 2 . The upper surface of the upper layer material is soaked and coated with diluted black pigment so that it can effectively absorb laser energy. The multi-layer material is fixed on a three-dimensional motion platform. The three-dimensional motion platform is controlled to make the millisecond laser focus on the upper surface of the upper layer material through a focusing lens. The parameters of the millisecond laser are adjusted: the power is 700 W, the duty cycle is 10%, the repetition frequency is 100 Hz, and the processing time is 20 ms. The millisecond laser is turned on to realize the through-hole processing of three layers of alumina ceramics by ablation at one time. After the processing is completed, the laser is turned off and the multi-layer material is removed. The middle layer alumina ceramic material is taken as the target sample, and a high-quality micropore result with an upper pore diameter of 53 μm, a middle pore diameter of 43 μm, a lower pore diameter of 41 μm, and a recast layer thickness of 23 μm is obtained. Its morphology is as shown in Figure 4 .

[0035] The above are only the preferred embodiments of the present invention and are not intended 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-quality laser drilling method for ceramic materials based on a sandwich structure, characterized in that: include: Step 1: Use a fixture to closely contact and fix the three layers of ceramics to form a sandwich structure, and apply paint to the upper surface of the upper layer so that it can efficiently absorb laser energy. The three layers of materials form a sandwich structure, which is the same or different materials in close contact with each other, and no other foreign matter can exist between each layer of material; Step 2: Use continuous laser or millisecond laser to focus on the coating treated surface, and realize through-hole processing of three layers of ceramics at one time by ablation. The thickness of the upper layer, the lower layer and the middle layer can be adjusted according to the actual choice, wherein the thickness of the upper layer and the lower layer is 50μm-5mm, and the thickness of the middle layer is 25μm-5mm; Step 3: Select the middle layer ceramic as the final through-hole processing sample to obtain a ceramic micropore processing result with a small diameter, small taper, less recast layer, and no closed pores. In addition, by adjusting the thickness of the first layer and the lower layer of ceramic, micropores with a diameter smaller than the laser spot can be obtained, and the taper of the micropores can be actively adjusted.

2. A high-quality laser drilling method for ceramic materials based on a sandwich structure according to claim 1, characterized in that: In step 1, the coating is a black dye or other coating that can enhance energy absorption, the purpose of which is to enhance the energy absorption of the multilayer material.

3. The high-quality laser drilling method for ceramic materials based on a sandwich structure according to claim 1 is characterized in that: In step 1, the clamp may be a simple clamp, the purpose of which is to enable the multi-layer materials to be in close contact and fixed without affecting the effect of the laser on the materials.

4. The high-quality laser drilling method for ceramic materials based on a sandwich structure according to claim 1 is characterized in that: In step 1, the ceramic material is an aluminum oxide material.

5. The high-quality laser drilling method for ceramic materials based on a sandwich structure according to claim 1 is characterized in that: The laser high-quality punched samples are taken from the middle layer and are not limited to the middle layer of the three-layer sample.

Images