Laser drilling method and processing equipment

Abstract

The present application provides a laser drilling method and a processing device. The laser drilling method is used to drill holes in a to-be-processed plate, and the to-be-processed plate includes a first material layer and a second material layer stacked. The laser drilling method includes: using a second laser to burn through the second material layer; using a first laser to burn through the first material layer. Among them, the absorption rate of the second material layer for the second laser is higher than the absorption rate of the second material layer for the first laser. By utilizing the characteristic that the absorption rate of the second material layer for the first laser is relatively low, when the first laser processes the first material layer, it can reduce the damage to the second material layer, ensure the processing quality of the holes, and can also improve the processing efficiency of different materials on the to-be-processed plate, thereby improving the overall processing efficiency. The present application also provides a processing device that applies the above laser drilling method. By adopting the laser drilling method and the processing device in this solution, the quality and efficiency of laser perforation can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of laser drilling processing, and particularly relates to a laser drilling method and processing equipment.

Background Art

[0002] With the rapid development of the electronics industry, the requirements for the printed circuit board manufacturing industry are getting higher and higher. The number of layers of the printed circuit board itself is increasing, the hole density is continuously increasing, and the diameter is continuously decreasing.

[0003] Generally speaking, the printed circuit board body includes a variety of different materials, such as resin, rubber, and copper. Since there are circuit conductors on both sides of the printed circuit board, there must be appropriate electrical connections between the two sides. This "bridge" between circuits is called a via hole. The mechanical drilling machines in the prior art cannot meet the product requirements in terms of production capacity and quality for processing micro via holes, while the high-energy and collimated properties of laser drilling provide a convenient way for the processing of micro via holes.

[0004] However, when using a laser to drill a printed circuit board composed of a combination of multiple materials in the prior art, it will bring quality defects such as uneven processing and a large difference in roundness between the incident light orifice and the exit light orifice, and the overall processing efficiency is not high, affecting the processing efficiency and quality.

Summary of the Invention

[0005] In view of this, the present application provides a laser drilling method and processing equipment to solve the problems of low processing efficiency and poor processing quality in the laser drilling solution in the prior art.

[0006] The present application provides a laser drilling method, which is used to perform a drilling operation on a to-be-processed board, and the to-be-processed board includes a first material layer and a second material layer stacked. The method includes: using a second laser to burn through the second material layer; using a first laser to burn through the first material layer. Wherein, the absorption rate of the second material layer for the second laser is higher than the absorption rate of the second material layer for the first laser.

[0007] In the above solution, by using the characteristic that the absorption rate of the second material layer for the first laser is relatively low, when the first laser processes the first material layer, it can reduce the damage to the second material layer, ensure the processing quality of the hole, and also improve the processing efficiency of different materials on the to-be-processed board, thereby improving the overall processing efficiency. Also, because different materials have different absorption rates for the same laser, when using a certain laser to burn one of the materials, even if the laser irradiates on another material, the absorption rate of the other material for this laser is not high, avoiding the influence caused by processing errors, and thus improving the accuracy of burning. In summary, the laser drilling method in this solution can improve the quality and efficiency of laser perforation.

[0008] In a possible design, the first material layer is a resin layer, the first laser is an infrared laser, the second material layer is a copper layer, and the second laser is an ultraviolet laser.

[0009] In the above solution, because the spot area of the infrared laser is large and the energy is high, its processing efficiency for the resin layer is significantly higher than that of the ultraviolet laser. And copper has a high absorption degree for the ultraviolet laser, so the double-sided copper-clad resin board can be quickly burned through under the irradiation of the infrared laser and the ultraviolet laser, and the holes processed have good quality. In a possible design, the thickness of the first material layer is 100 - 400 μm.

[0010] In the above solution, the first material layer within the above thickness range can be well burned through under the irradiation of the first laser and form a high-quality hole structure.

[0011] In a possible design, the thickness of the second material layer is 5 - 15 μm.

[0012] In the above solution, the second material layer within the above thickness range can be well burned through under the irradiation of the second laser and form a high-quality hole structure.

[0013] In a possible design, the burning through of the first material layer using the first laser includes:

[0014] The first material layer is irradiated multiple times with the first laser, and the focusing position during each irradiation moves in the thickness direction of the first material layer, and the moving direction of the focusing position is the same as the irradiation direction of the first laser.

[0015] In the above solution, by changing the focusing position of the first laser on the first material layer, the first laser can burn the first material layer layer by layer, and then form a hole structure with good surface quality and high uniformity on the first material layer.

[0016] In a possible design, the burning through of the first material layer using the first laser includes:

[0017] The first laser forms multiple spots focused on the first material layer, and the multiple spots are arranged around the center of the processing position.

[0018] In the above solution, multiple small spots are combined into a "large spot". This kind of hole processing method can evenly distribute the energy at the edge of the hole and the energy in the center part of the hole, effectively preventing the burr problem caused by too small energy at the edge.

[0019] In a possible design, the second material layer includes an upper surface layer disposed above the first material layer and a lower surface layer disposed below the first material layer, the first laser and the second laser are both irradiated in a direction from the upper surface layer to the lower surface layer, and the laser drilling method includes:

[0020] S1, the upper surface layer is irradiated with the second laser and burned through, and the spot diameter formed by the second laser on the upper surface layer is D1. S2, the first material layer is irradiated with the first laser and burned through, and the spot diameter formed by the first laser on the first material layer is D2. S3, the lower surface layer is irradiated with the second laser and burned through, and the spot diameter formed by the second laser on the lower surface layer is D3. Wherein, D2>D1>D3.

[0021] In the above scheme, the upper surface layer, the first material layer and the lower surface layer are burned in sequence, and the overall structure and quality of the holes on the plate to be processed are adjusted by controlling the diameter of the light spot irradiated on the upper surface layer, the first material layer and the lower surface layer, thereby ensuring that the surface quality of the processed hole is smooth, the roundness of the light entrance hole and the light exit hole is similar, and the hole shape is highly consistent.

[0022] In a possible design, the diameter of the light spot formed by the first laser on the first material layer is larger than the diameter of the light spot formed by the second laser on the upper surface layer by 20-30 microns.

[0023] In the above scheme, by limiting the difference between the spot diameter formed by the first laser on the first material layer and the spot diameter formed by the second laser on the upper surface layer, when processing the first material layer located in the middle layer, the surface quality of the hole processed is good and the verticality is high.

[0024] The present application also provides a processing device, comprising: a laser emitting device and a switching device, wherein the laser emitting device comprises a first emitting head capable of emitting a first laser and a second emitting head capable of emitting a second laser. The switching device is arranged below the laser emitting device, and is used to move a plate to be processed placed below the first emitting head to below the second emitting head, and is also used to move a plate to be processed placed below the second emitting head to below the first emitting head.

[0025] In the above scheme, the plate to be processed can change its position under the first emission head and the second emission head of the laser emitting device under the drive of the switching device, so that the plate to be processed can form a through-hole structure under the alternating irradiation of the first laser and the second laser. The use of this equipment for hole processing can improve production efficiency and processing quality.

[0026] In a possible design, the processing device further includes a loading and unloading device and a table. The table is disposed below the laser emitting device and is used to carry the plate to be processed. The loading and unloading device is disposed on one side of the table and is used to place the plate to be processed on the table and also used to take the plate to be processed away from the table.

[0027] In the above solution, by adding a loading and unloading device, the automation degree of the drilling process of the plate to be processed is improved, the labor burden of workers is reduced, and the production efficiency and production quality are improved.

[0028] Other features and advantages of the embodiments of the present application will be described in the subsequent description, and part of them will be obvious from the description, or will be understood by implementing the embodiments of the present application. The objectives and other advantages of the embodiments of the present application are achieved and obtained by the structures specifically pointed out in the description and the drawings.

Description of the Drawings

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0030] Figure 1 It is a flowchart of the laser drilling method provided by the embodiment of the present application;

[0031] Figure 2 It is a working schematic diagram of drilling the upper surface layer provided by the embodiment of the present application;

[0032] Figure 3 It is a working schematic diagram of drilling the first material layer provided by the embodiment of the present application;

[0033] Figure 4 It is a position schematic diagram of multiple light spots when drilling the first material layer provided by the embodiment of the present application;

[0034] Figure 5 It is a working schematic diagram of drilling the lower surface layer provided by the embodiment of the present application.

[0035] Reference numerals:

[0036] 100, plate to be processed; 1, upper surface layer; 2, first material layer; 3, lower surface layer;

[0037] The drawings here are incorporated into the description and form a part of this description, showing the embodiments consistent with the present application, and are used together with the description to explain the principles of the present application.

Detailed Implementation Manner

[0038] To better understand the technical solution of the present application, the embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0039] It should be clear that the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0040] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms of "a", "the" and "said" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0041] It should be understood that the term " / and / " used herein is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " herein generally represents an "or" relationship between the associated objects before and after.

[0042] It should be noted that the orientation terms such as "upper", "lower", "left", and "right" described in the embodiments of the present application are described from the angles shown in the accompanying drawings, and should not be construed as a limitation on the embodiments of the present application. In addition, in the context, it should also be understood that when it is mentioned that an element is connected "above" or "below" another element, it can not only be directly connected "above" or "below" another element, but also be indirectly connected "above" or "below" another element through an intermediate element.

[0043] When directly processing a double-sided copper-clad PCB board by laser (or processing the core layer in a multi-layer PCB board), there are obvious differences in the states of the laser beams on the incident surface and the exit surface. The collimation of the laser beam on the incident surface is good, and the energy acting on the material surface is balanced; while on the exit surface, after the beam passes through the processing medium (the surface copper foil and the substrate of FR-4 grade), the beam will become partially divergent, and at the same time its energy will also decay accordingly. Therefore, there are great differences in the processing quality (hole diameter size and hole diameter roundness) between the incident surface and the exit surface. The present application uses different laser types for different material layers of the PCB board, so that the overall consistency of the hole openings after laser processing is better, and it can meet the requirements of large-scale industrial production.

[0044] Next, according to the structure of the laser drilling method provided by the embodiments of the present application, its specific embodiments will be described.

[0045] The present application provides a method for laser drilling a to-be-processed plate 100, where the to-be-processed plate 100 includes a first material layer and a second material layer. The method includes: using a second laser to burn through the second material layer; using a first laser to burn through the first material layer. Wherein, the absorption rate of the second material layer to the second laser is higher than the absorption rate of the second material layer to the first laser, and the absorption rate of the first material layer to the first laser may be higher than or equal to the absorption rate of the first material layer to the second laser.

[0046] The to-be-processed plate 100 can be a circuit board (also called a copper-clad laminate) commonly used in the electronics industry. The circuit board mainly includes: a substrate, copper foil, and a copper-clad laminate adhesive. The substrate mainly includes a resin laminate composed of a polymer synthetic resin and a reinforcing material. There are many types of synthetic resins, commonly used ones are phenolic resin, epoxy resin, polytetrafluoroethylene, etc. The reinforcing materials are generally of two types, paper and cloth, which determine the mechanical properties of the substrate, such as solder immersion resistance, bending strength, etc. Copper foil is a key material for manufacturing copper-clad laminates. It has a high conductivity and good weldability. The thinner the copper foil, the easier it is to etch and drill, and it is especially suitable for manufacturing high-density printed boards with complex circuits. The copper-clad laminate adhesive is an important factor in whether the copper foil can be firmly attached to the substrate. It can be a common glue, and the performance of the adhesive determines the peel strength of the copper-clad laminate.

[0047] In this embodiment, the to-be-processed plate 100 can be a three-layer structure of "second material layer, first material layer, second material layer", or the to-be-processed plate can also be other structures formed by stacking and combining the first material layer and the second material layer in any order. The absorption rate of the second material layer to the second laser is higher than the absorption rate of the second material layer to the first laser. The absorption rate of a material to a laser can characterize the ease of laser energy deposition into the material. The higher the absorption rate, the more laser energy is transferred to the material, and the better the burning effect. In some embodiments, the processing efficiency of the first material layer when processed with the first laser can be higher than the processing efficiency of the first material layer when processed with the second laser. Thus, the overall processing and drilling efficiency can be improved.

[0048] When using the laser drilling method in this embodiment, the to-be-processed plate can be placed horizontally first, and the second laser is used to irradiate and process the second material layer. When the second material layer is completely burned through and the first material layer below it is exposed, at this time, the first laser is switched to irradiate and process the first material layer. During this process, the first laser needs to pass through the hole formed by the second laser in the second material layer. Therefore, the first laser will inevitably come into contact with the hole wall or other parts of part of the second material layer. However, because the absorption rate of the second material layer to the first laser is not high, this process will not have too much impact on the hole wall of the second material layer, thereby ensuring the processing quality of the to-be-processed plate.

[0049] In addition, since different types of lasers have different processing efficiencies for the same material (for example, the processing efficiency of infrared lasers for resin is higher than that of ultraviolet lasers for resin), when selecting a laser, it is possible to choose a laser with a high processing efficiency for the material as much as possible, thereby improving the overall drilling speed.

[0050] In summary, in this embodiment, by taking advantage of the different processing efficiencies of different lasers for different types of materials, a specific type of laser is used to burn a specific material, so that the processing efficiency of different materials on the plate to be processed is improved, thereby improving the overall processing efficiency. Also, because different materials have different absorption rates for the same laser, when using a certain laser to burn one material, even if the laser irradiates another material, the absorption rate of the other material for this laser is not high, avoiding the influence caused by processing errors, and thus improving the accuracy of burning. In summary, the laser drilling method in this solution can improve the quality and efficiency of laser perforation.

[0051] In one embodiment, the first material layer is a resin layer, the first laser is an infrared laser, the second material layer is a copper layer, and the second laser is an ultraviolet laser.

[0052] Since copper has a high absorption degree for ultraviolet lasers and a low absorption degree for infrared lasers, the holes processed on a double-sided copper-clad resin board under the irradiation of infrared lasers and ultraviolet lasers have good quality. Also, because the spot area of infrared lasers is large and the energy is high, and its energy is usually one order of magnitude higher than that of ultraviolet lasers, the processing efficiency of the first material layer using an infrared laser is also significantly higher than that of an ultraviolet laser. In this way, the overall drilling speed is increased.

[0053] Specifically, the absorption rate of materials varies with the wavelength of the laser. The inventor found through experiments and analysis that: when copper foil and glass cloth have a high absorption rate in the region below 0.3μm of ultraviolet light, but it drops significantly when entering visible light and infrared light. Resin materials can maintain a relatively high absorption rate in all three spectral ranges (ultraviolet light, visible light, infrared light).

[0054] When the laser is incident on the material surface, part of the light energy with energy E0 is reflected, and the remaining energy is absorbed by the object. According to the law of conservation of energy, it can be simply written as:

[0055] E0 = E_reflection + E_absorption;

[0056] After dividing both sides of the above formula by E0, we get

[0057] 1 = E_reflection / E0 + E_absorption / E0 = R + ρ

[0058] In the formula, R is the reflection coefficient, and ρ is the surface absorption coefficient.

[0059] For a laser vertically incident on the surface of a material, the reflection coefficient is given by the Fresnel formula:

[0060] R = ∣(n - 1) / (n + 1)∣ 2 ;

[0061] In the formula, n is the refractive index of the material. The refractive index of the material can be determined experimentally, and there are various measurement methods, which are not limited here. For example: for solid materials, the minimum deviation angle method or the autocollimation method is commonly used; for liquid materials, the critical angle method (Abbe refractometer) is commonly used; for gas materials, the more precise interference method (Rayleigh interferometer) is used.

[0062] Therefore, the surface absorption coefficient is: ρ = 1 - R = 1 - ∣(n - 1) / (n + 1)∣ 2 .

[0063] Since the refractive index of the material is a function of wavelength, for lasers of different wavelengths, the absorption coefficient of the material is different. Usually, for the same material, the shorter the wavelength, the larger the absorption coefficient.

[0064] In summary, copper has a low absorption degree for infrared lasers and a high absorption degree for ultraviolet lasers.

[0065] In one of the embodiments, the thickness of the first material layer is 100 - 400 μm.

[0066] The inventor found through experiments that when the thickness of the first material layer is less than 100 μm, the overall stiffness of the plate to be processed is poor, and the thermal deformation rate is large during the laser processing; when the thickness of the first material layer is greater than 400 μm, due to the relatively thick thickness, the laser transmissivity becomes poor, and due to the attenuation of the laser, the hole structure formed on the first material layer is likely to form a funnel shape with a large upper part and a small lower part, resulting in poor roundness and perpendicularity quality of the whole hole.

[0067] When the thickness of the first material layer is between 100 - 400 μm, the first material layer can be well burned through and form a high-quality hole structure under the irradiation of the first laser.

[0068] In one of the embodiments, the thickness of the second material layer is 5 - 15 μm.

[0069] The inventor found through experiments that when the thickness of the second material layer is less than 5 μm, the overall stiffness of the plate to be processed is poor, the second material layer has a large thermal deformation rate during the laser processing, and it is easy to peel off from the first material layer; when the thickness of the second material layer is greater than 15 μm, due to the relatively thick thickness, the laser transmissivity becomes poor, and due to the attenuation of the laser, the hole structure formed on the second material layer is likely to form a funnel shape with a large upper part and a small lower part, resulting in poor roundness and perpendicularity quality of the whole hole.

[0070] When the thickness of the second material layer is within 5 - 15 μm, the second material layer can be well burned through under the irradiation of the second laser and form a high-quality hole structure.

[0071] In one embodiment, using the first laser to burn through the first material layer includes:

[0072] Irradiating the first material layer with the first laser multiple times, and the focusing position moves in the thickness direction of the first material layer each time, and the moving direction of the focusing position is the same as the irradiation direction of the first laser.

[0073] Since the energy of the laser is most concentrated at the focusing position, and the thickness of the first material layer is relatively thick, so in this embodiment, the focusing position of the first laser on the first material layer is continuously changed. Specifically, at the beginning of processing, the first laser is focused on the surface of the first material layer closest to the first laser emission point. After a certain time, this part of the first material layer is removed. Subsequently, the focusing position of the first laser is adjusted to the surface of the first material layer slightly farther from the first laser emission point, and this part of the material is removed. In this way, the focusing position is gradually adjusted to burn through the entire first material layer.

[0074] In this embodiment, by changing the focusing position of the first laser on the first material layer, the first laser can burn the first material layer layer by layer, thereby forming a hole structure with good surface quality and high uniformity on the first material layer.

[0075] In one embodiment, using the first laser to burn through the first material layer 2 includes:

[0076] The first laser forms a plurality of light spots focused on the first material layer 2, and the plurality of light spots are arranged around the center of the processing position.

[0077] Please refer to Figure 3 and Figure 4 , the sizes and diameters of the plurality of light spots can be the same or different. When the plurality of light spots are arranged around the center of the processing position, the edges of the plurality of light spots are fitted into a complete circle, and the coverage range of the complete circle coincides with the processing position, that is, the aperture size of the position to be processed is the same as the diameter of the complete circle formed by fitting the edges of the plurality of light spots.

[0078] In this embodiment, a plurality of small light spots are combined into a "large light spot", avoiding the defect that the energy is high at the center of a single light spot and low at the edge. This kind of hole machining method can evenly distribute the energy at the edge of the hole and the energy at the center part of the hole, effectively preventing the burr problem caused by too small energy at the edge.

[0079] In one embodiment, please refer to Figure 2 , Figure 3 and Figure 5, It should be noted that the waist-drum-shaped figure in the figure represents the focusing range of the laser, and the circle at the center of the waist-drum shape represents the focal point of the laser. The second material layer includes an upper surface layer 1 disposed above the first material layer 2 and a lower surface layer 3 disposed below the first material layer 2. Both the first laser and the second laser are irradiated in the direction from the upper surface layer 1 to the lower surface layer 3. The laser drilling method includes:

[0080] S1, please refer to Figure 2 , Use the second laser to irradiate the upper surface layer 1 and burn it through. The spot diameter formed by the second laser on the upper surface layer 1 is D1. S2, please refer to Figure 3 , Use the first laser to irradiate the first material layer 2 and burn it through. The spot diameter formed by the first laser on the first material layer 2 is D2. S3, please refer to Figure 5 , Use the second laser to irradiate the lower surface layer 3 and burn it through. The spot diameter formed by the second laser on the lower surface layer 3 is D3. Among them, D2 > D1 > D3.

[0081] In this embodiment, the three-layer material is irradiated three times, efficiently utilizing the burning advantages of different lasers for different materials, and burning through the upper surface layer 1, the first material layer 2, and the lower surface layer 3 in sequence. This solution adjusts the diameter of the spots irradiated on the upper surface layer 1, the first material layer 2, and the lower surface layer 3. Specifically, the value of D2 is greater than D1 to avoid the attenuation of the first laser passing through the hole wall of the upper surface layer 1 and affecting the irradiation range of the first laser; while the value of D3 is less than D1 to avoid the absorption of the second laser by the material on the hole wall of the first material layer 2 when passing through the first material layer 2 and affecting the burning efficiency of the second laser on the lower surface layer 3.

[0082] The solution in this embodiment can ensure that the surface quality of the processed hole opening is smooth, and the roundness of the light-incident hole opening and the light-emitting hole opening is similar, and the hole shape consistency is high.

[0083] In one of the embodiments, the range in which the spot diameter formed by the first laser on the first material layer is larger than the spot diameter formed by the second laser on the upper surface layer is 20 to 30 micrometers. That is, the spot diameter formed by the first laser on the first material layer is D, and the spot diameter formed by the second laser on the upper surface layer is d, 20μm ≤ D - d ≤ 30μm. Optionally, in one of the embodiments, in combination with specific experiments, in order to improve the control accuracy, the spot diameter formed by the first laser on the first material layer can be 25 micrometers larger than the spot diameter formed by the second laser on the upper surface layer.

[0084] By defining the difference between the spot diameter formed by the first laser on the first material layer 2 and the spot diameter formed by the second laser on the upper surface layer 1, when processing the first material layer 2 located in the middle layer, the surface quality of the processed hole is good and the perpendicularity is high.

[0085] The present application also provides a processing device, including: a laser emitting device and a switching device. The laser emitting device includes a first emitting head capable of emitting a first laser and a second emitting head capable of emitting a second laser. A table can be arranged below the laser emitting device, and the table is used to carry the plate to be processed. The switching device is arranged below the laser emitting device, and it is used to move the plate to be processed placed below the first emitting head to below the second emitting head, and it is also used to move the plate to be processed placed below the second emitting head to below the first emitting head.

[0086] The laser emitting device can be any device capable of emitting lasers such as ultraviolet lasers and infrared lasers. The table can be a workbench, and positioning devices such as positioning pins for positioning the plate to be processed can be arranged thereon.

[0087] The switching device can be a manipulator or an automatic material changing device assembled by a cylinder, a pneumatic claw and a PLC device. The switching device can move the plate to be processed placed below the first emitting head to below the second emitting head, and the switching device can also move the plate to be processed placed below the second emitting head to below the first emitting head. This action can be carried out synchronously to improve the action efficiency.

[0088] In this embodiment, the plate to be processed can change its position under the drive of the switching device below the first emitting head and the second emitting head of the laser emitting device, so that the plate to be processed can form a through-hole structure under the alternating irradiation of the first laser and the second laser. Using this device for hole processing can improve the production efficiency and processing quality.

[0089] In one of the embodiments, the processing device further includes a loading and unloading device. The loading and unloading device is arranged on one side of the table, and the loading and unloading device is used to place the plate to be processed on the table, and the loading and unloading device is also used to take the plate to be processed away from the table.

[0090] The loading and unloading device can adopt a manipulator or manual labor. During mass production, the loading and unloading device can quickly load and unload the plate to be processed, thereby improving the overall processing efficiency of laser drilling.

[0091] This embodiment improves the automation degree of the drilling process of the plate to be processed by adding a loading and unloading device, reduces the labor burden of workers, and improves the production efficiency and production quality.

[0092] In order to further improve the quality of laser drilling, the present application further processes the structure of the plate to be processed, which mainly includes:

[0093] In this embodiment, the plate to be processed includes an upper surface layer, a first material layer, and a lower surface layer that are sequentially stacked. A first energy absorption portion is provided on the upper surface layer, and a second energy absorption portion is provided on the lower surface layer. Among them, the surface roughness of the first energy absorption portion is higher than that of the second energy absorption portion.

[0094] In the above solution, a laser can be used to drill the plate to be processed, and the laser irradiates the plate to be processed in the direction from the upper surface layer to the lower surface layer. After the laser burns through the upper surface layer and the first material layer, it reaches the lower surface layer. At this time, the laser is interfered by the hole walls of the burn-through holes of the upper surface layer and the first material layer, and there is a certain attenuation of the laser, so the burning efficiency and burning effect on the lower surface layer are poor. In order to avoid the difference in the burning effect of the laser on the upper surface layer and the lower surface layer in this solution, a first energy absorption portion with a lower roughness is provided on the upper surface layer, and a second energy absorption portion with a higher roughness is provided on the lower surface layer, so as to improve the absorption rate of the attenuated laser by the second energy absorption portion of the second surface layer. Furthermore, the quality of the holes burned through by the laser on the upper surface layer and the lower surface layer is relatively close, the difference in hole diameter is small, and the difference in roundness is small, thereby improving the product quality of the plate to be processed.

[0095] In a possible design, the upper surface layer and the lower surface layer are copper layers, and the first material layer is a resin layer.

[0096] In the above solution, the materials of the upper surface layer and the lower surface layer both include copper. In this way, the advantages of good electrical conductivity and good laser processability of copper can be utilized to drill it, while the material of the first material layer includes resin, and the characteristics of good insulation and good toughness of the resin can be utilized to ensure the working stability and structural strength of the plate to be processed.

[0097] In a possible design, the thickness of the upper surface layer is greater than the thickness of the lower surface layer.

[0098] In the above solution, it is further defined that the thickness of the upper surface layer is greater than the thickness of the lower surface layer. In this way, during the laser drilling process, after the laser burns through the upper surface layer and the first material layer, it reaches the lower surface layer. At this time, the laser is interfered by the hole walls of the burn-through holes of the upper surface layer and the first material layer, and there is a certain attenuation of the laser. And the thinner lower surface layer is more easily burned through by the laser. The influence after the attenuation of the laser energy is balanced by using the thinned lower surface layer, further ensuring that the quality of the holes burned through by the laser on the upper surface layer and the lower surface layer is relatively close, the difference in hole diameter is small, and the difference in roundness is small.

[0099] 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 within the scope of protection of the present invention.

Claims

1. A laser drilling method, which is used to perform a drilling operation on a to-be-processed plate. The to-be-processed plate includes a first material layer and a second material layer stacked on top of each other. Characterized in that, Comprising: Using a second laser to burn through the second material layer; Using a first laser to burn through the first material layer; Wherein, the absorption rate of the second material layer to the second laser is higher than the absorption rate of the second material layer to the first laser; The second material layer includes an upper surface layer disposed above the first material layer and a lower surface layer disposed below the first material layer. Both the first laser and the second laser are irradiated in the direction from the upper surface layer to the lower surface layer. The laser drilling method includes: S1, using the second laser to irradiate the upper surface layer and burn through it. The spot diameter formed by the second laser on the upper surface layer is D1; S2, using the first laser to irradiate the first material layer and burn through it. The spot diameter formed by the first laser on the first material layer is D2; wherein, when the first laser forms multiple spots on the first material layer by focusing, the multiple spots form a large spot, and the diameter D2 of the large spot is the same as the aperture size of the to-be-processed position; S3, using the second laser to irradiate the lower surface layer and burn through it. The spot diameter formed by the second laser on the lower surface layer is D3; Wherein, D2 > D1 > D3.

2. The laser drilling method according to claim 1, Characterized in that, The first material layer is a resin layer, the first laser is an infrared laser, the second material layer is a copper layer, and the second laser is an ultraviolet laser.

3. The laser drilling method according to claim 1 or 2, Characterized in that, The thickness of the first material layer is 100 - 400 μm.

4. The laser drilling method according to claim 1 or 2, Characterized in that, The thickness of the second material layer is 5 - 15 μm.

5. The laser drilling method according to claim 1, Characterized in that, The step of using the first laser to burn through the first material layer includes: Using the first laser to irradiate the first material layer multiple times, and the focusing position moves in the thickness direction of the first material layer each time of irradiation. The moving direction of the focusing position is the same as the irradiation direction of the first laser.

6. The laser drilling method according to claim 1, Characterized in that, The step of using the first laser to burn through the first material layer includes: The first laser forms multiple spots by focusing on the first material layer, and the multiple spots are arranged around the center of the processing position.

7. The laser drilling method according to claim 1, Characterized in that, The range that the spot diameter formed by the first laser on the first material layer is larger than the spot diameter formed by the second laser on the upper surface layer is 20 microns - 30 microns.

8. A processing device, which applies the laser drilling method according to any one of claims 1 - 7, Characterized in that, The processing device includes; A laser emission device, the laser emission device comprising a first emission head capable of emitting a first laser and a second emission head capable of emitting a second laser; and A switching device, the switching device being disposed below the laser emission device, which is used to move a workpiece plate placed below the first emission head to below the second emission head, and is further used to move a workpiece plate placed below the second emission head to below the first emission head.

9. The processing equipment according to claim 8, characterized in that the processing equipment further comprises a loading and unloading device and a table disposed below the laser emission device, the table being used to carry a workpiece plate, the loading and unloading device being disposed on one side of the table, the loading and unloading device being used to place a workpiece plate on the table, and the loading and unloading device is further used to take away the workpiece plate from the table.

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