Laser material selection and ablation method for laminated material and laser processing equipment

Abstract

The application discloses a kind of laser material selection etching method and laser processing equipment of laminated material.The laser material selection etching method includes: using the time-domain shaping means of pulse, the single pulse in the ultrafast laser near-infrared single pulse sequence in eigenstate is widened in time domain under the premise of keeping total energy unchanged;Using the frequency-domain shaping means of laser, the wavelength conversion of the widened light beam is carried out;Using the wavelength converted light beam and focusing, the dielectric material removal energy threshold F th_1 And the removal energy threshold F th_2 Of conductive material are measured respectively when the equivalent pulse number N of the laminated material to be processed;Laser pulse is applied to the conductive layer side of the laminated material to be processed, and the pulse energy greater than F th_2 And less than F th_1 , the equivalent pulse number N of processing parameter is used, and the conductive layer depth is processed to the conductive material film-dielectric interface.The precision of selected area removal of conductive layer material is realized without damage to dielectric layer.

Description

Technical Field

[0001] This application relates to the technical field of ultrafast laser processing, and in particular to a laser selective etching method and laser processing equipment for laminated materials. Background Technology

[0002] Laminated material configurations, formed by organically combining dielectric insulators and conductive materials, generally possess unique mechanical, thermal, or electrical properties. Therefore, they are widely used in high-load-bearing, electromagnetically functional payload products in aerospace, electronics, and weaponry. The conductive film-dielectric layer and other materials used in flexible thin-film antennas are typical examples of laminated material configurations. By selectively removing certain components from the material, the electromagnetic functional structure of the product can be customized. For instance, by selectively etching away the conductive film on the surface of the conductive film-dielectric layer, electromagnetic functional pattern structures that function as electrical interconnects, electromagnetic induction, and supercapacitors can be formed. These patterns can be used to construct large flexible thin-film antennas and conformal wires, supporting critical requirements such as high-resolution remote sensing and high-capacity / strong anti-interference communication.

[0003] Laser manufacturing, due to its advantages in flexibility, efficiency, and precision, is an ideal means of constructing metallized patterns on the surface of dielectric materials and a favorable method for selectively removing resin from the surface of fiber-reinforced resin composites. However, due to the vastly different optical, electrical, and thermal properties of the dielectric insulating material and the conductive material in this type of laminated material configuration, coupled with the intertwined and mixed characteristics of the two materials at the interface, laser processing struggles to precisely and selectively remove one component layer without damaging the other. For example, to ensure good bonding strength between the dielectric substrate of an antenna product and its surface metal film, it is generally necessary to perform related treatments to create a good physical interlock at the interface between the dielectric substrate and the metal film, ensuring that the metal film does not detach or delaminate under alternating hot and cold environments. These metal film anchors embedded in the dielectric substrate undoubtedly further increase the difficulty of selectively removing the metal material without damaging the dielectric substrate. Existing methods generally employ short-pulse lasers such as nanosecond infrared or ultraviolet lasers, or ultrafast lasers of intrinsic wavelengths such as infrared ultrafast lasers, to selectively etch the metal pattern on the dielectric surface to form an electromagnetic pattern. For nanosecond lasers, the long pulse duration leads to significant adverse effects such as thermal diffusion, easily causing thermal debonding of the metal film layer on the dielectric substrate surface. For ultrafast lasers such as near-infrared femtosecond lasers, which are at their intrinsic wavelengths, although the extreme pulse duration results in minimal thermal diffusion effects, the low absorption rate of metal materials for the near-infrared wavelengths of ultrafast lasers in their intrinsic band leads to a high energy removal threshold for the metal film material. This makes it difficult to achieve a processing threshold where the metal film processing threshold is much lower than that of the dielectric material, resulting in easy processing. Consequently, when etching the metal film to the metal-dielectric interface, the dielectric material is easily damaged. These traditional methods result in significant problems with the mechanical properties of the product and the bonding strength of the metal pattern.

[0004] Therefore, there is an urgent need to develop a laser material selection processing method that can precisely and selectively remove one layer of material in a laminated material structure without damaging the other layer. Summary of the Invention

[0005] This application addresses the problem in existing technologies where laser processing struggles to precisely and selectively etch a specific component of a laminated material without damaging other material components. It provides a laser processing method that overcomes this difficulty by collaboratively shaping the temporal and frequency domain characteristics of the laser blade.

[0006] In a first aspect, a laser selective etching method for laminated materials is provided, comprising:

[0007] Using time-domain shaping techniques, the duration of each pulse in an ultrafast laser near-infrared single-pulse sequence in its intrinsic state is... t A single pulse with a value of 0 is time-domain broadened while keeping the total energy constant, such that the total duration after broadening is... t p , t p >t0;

[0008] By using laser frequency domain shaping techniques, the wavelength of the broadened beam is transformed so that its center wavelength is λ.

[0009] By using a wavelength-converted and focused beam, the equivalent pulse number is measured for the laminated materials to be processed. N The dielectric material removal energy threshold at that time F th_1 and the energy threshold for removing conductive materials F th_2 The laminated material to be processed is a dielectric layer-conductive layer composite material;

[0010] A laser pulse is applied to one side of the conductive layer of the laminate material to be processed, using a pulse larger than [missing value]. F th_2 and less than F th_1 The pulse energy, using the equivalent number of pulses is N The processing parameters are selected, and the depth of the conductive layer is processed to the interface between the conductive material film and the dielectric.

[0011] In conjunction with the first aspect, in some implementations of the first aspect, the dielectric layer is made of a material with a conductivity of not more than 10 at room temperature (25°C). -11S / m single-component materials or composite materials, the conductive layer is a metal or metal-like film layer with a total thickness of 0.2μm to 200μm, the film material includes copper and its alloys, gold and its alloys, aluminum and its alloys, silver and its alloys, nickel and its alloys, platinum and its alloys, chromium and its alloys, as well as metal films and graphitized carbon composed of different types of these metals and their alloys.

[0012] In conjunction with the first aspect, in some implementations of the first aspect, the material being processed is a copper-plated polyimide film, and the thickness of the copper-plated main layer is 2.0 μm; before copper plating, the surface of the polyimide film is subjected to plasma treatment to roughen the surface, so that synapses of 0.5 μm to 1 μm are embedded in the polyimide film under the copper film.

[0013] In conjunction with the first aspect, in some implementations of the first aspect, the laser center wavelength of the ultrafast laser near-infrared single-pulse sequence is between 780 nm and 2000 nm, and the duration of a single pulse is... t 0 is a value ranging from 5fs to 2000fs based on half-height and full width.

[0014] In conjunction with the first aspect, in some implementations of the first aspect, the total duration after widening t p The value ranges from 2.0ps to 1000ps, and the total duration after stretching is... t p The pulse includes any of the following forms: containing ≥2 sub-pulses and with a total duration from the start of the first sub-pulse to the end of the last sub-pulse of . t p It contains only one pulse and its duration is measured in half-width at half maximum (FWHM). t p The situation.

[0015] In conjunction with the first aspect, in some implementations of the first aspect, the center wavelength λ of the beam after wavelength conversion is in the range of 650nm~430nm.

[0016] In conjunction with the first aspect, in some implementations of the first aspect, when the focused spot is an elliptical or circular Gaussian spot, the equivalent pulse number is... N satisfy:

[0017]

[0018] in, The equivalent number of pulses along the direction of the relative velocity between the beam and the workpiece. To focus the characteristic diameter of the elliptical light spot in this direction, the light intensity attenuation from the center of the spot is 1 / e of the intensity at the center of the spot. 2 The required extension is twice the diameter; The equivalent number of pulses is perpendicular to the direction of relative motion between the beam and the workpiece. To focus the characteristic size of the elliptical spot in this direction, the light intensity attenuation from the center of the spot is 1 / e of the intensity at the center of the spot. 2 The required extension is twice the diameter; v The velocity of the light beam relative to the workpiece. f The total duration is t p The time repetition frequency between each time domain envelope and the time domain envelope. L To be parallel to the velocity v The distance between adjacent fill trajectories in the direction. Specifically, when... L =0, meaning there are no adjacent filled trajectories and only one trajectories along the velocity. v When machining the trajectory in the direction, ;when The time indicates that the focused beam is a Gaussian beam that is a perfect circle.

[0019] In a second aspect, a laser selective etching product for laminated materials is provided, the product being prepared as described in any of the implementations of the first aspect above.

[0020] Thirdly, a laser processing apparatus is provided, which is used to perform the method as described in any of the implementations of the first aspect above.

[0021] In conjunction with the third aspect, in some implementations of the third aspect, the laser processing equipment includes: an ultrafast laser source, a time-domain stretching module, a wavelength compression module, a processing head system, and a load-bearing and motion system;

[0022] The time-domain stretching module is used to perform time-domain shaping on laser light emitted from an ultrafast laser source, so that, while keeping the total energy constant, the laser light of each duration is stretched. t A single pulse of 0 is broadened in the time domain, such that the total duration of the broadened time domain envelope is... t p , t p >t0;

[0023] The wavelength compression module can be used to compress the wavelength of laser light so that the value of the center wavelength λ after wavelength transformation meets the requirements.

[0024] The load-bearing and motion system is used to set up the laminated sample to be processed;

[0025] The processing head system applies the laser output from the wavelength compression module to the laminated sample to be processed.

[0026] Compared with the prior art, the solution provided in this application has at least the following beneficial technical effects:

[0027] (1) The present invention provides a laser selective etching method and laser processing equipment for laminated materials, which is a method for controlling the material removal energy threshold by using an ultrafast laser scalpel to coordinate time-domain and frequency-domain shaping. The ultrafast laser pulse in its intrinsic state, i.e., a laser with near-infrared frequency characteristics and a single-pulse sequence time-domain characteristic, is transformed into a laser energy with a shorter wavelength and a longer equivalent time-domain duration. This can increase the removal energy threshold of the dielectric layer while decreasing the removal energy threshold of the conductive layer. This is because the light absorption mechanism of the conductive layer material in the laminated material is linear absorption, and when the total pulse duration... t p At speeds below tens of picoseconds, threshold removal is required. t p The removal threshold of the conductive layer material remains almost unchanged when the ultrafast single pulse is broadened into a single pulse with a longer duration, or into a sequence of ultrafast pulses with a total duration of less than tens of picoseconds. However, for dielectric materials with a nonlinear absorption mechanism, the removal threshold energy spikes due to time-domain broadening. Simultaneously, appropriate wavelength compression can significantly reduce the reflectivity of the conductive layer material, thereby drastically lowering its removal energy threshold, while only slightly altering the removal energy threshold of the dielectric layer. In summary, by utilizing the combined time-domain and frequency-domain shaping of an ultrafast laser scalpel, it is possible to achieve a removal threshold for the conductive layer material that is far lower than that for the dielectric layer material. This provides a foundation for precise selective removal of the conductive layer material without damaging the dielectric layer.

[0028] (2) The laser selective etching method and laser processing equipment for laminated materials provided by this invention are high-efficiency methods for selective processing of heterogeneous laminated materials. Although near-infrared ultrafast lasers are converted to shorter wavelengths through optical means, this comes at the cost of sacrificing some usable laser power. However, this does not mean a reduction in the efficiency of laser selective processing of laminated materials. This is because appropriate compression of the light wavelength can significantly increase the light absorption rate of the conductive layer material, thereby significantly reducing the removal energy threshold of the conductive layer material. In other words, the significant increase in light energy utilization is sufficient to compensate for the loss of usable power caused by wavelength compression. Therefore, this method is also a way to improve processing efficiency.

[0029] (3) The laser selective etching method and laser processing equipment for laminated materials provided by this invention can achieve pulse time-domain broadening through simple or mature modules such as strongly dispersive transparent media, thin film beam splitters, and gratings, while wavelength compression can be achieved for most materials through frequency doubling crystal compression, which has the characteristics of low cost, simple method and flexibility. At the same time, the method for calculating the equivalent pulse number is simple and reliable. Therefore, this invention has the characteristics of low cost and simple reliability. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of a laser material selection and etching method for laminated materials and a laser processing equipment according to the present invention.

[0031] Figure 2 This document describes the process of a laser selective etching method for laminated materials according to the present invention.

[0032] Figure 3 This is an optical microscope image showing the effect of selectively etching the copper film on the copper-coated polyimide laminate structure after applying the present invention.

[0033] Figure 4 The image shows the effect of using a conventional ultrafast laser to regionally etch copper lines on a copper-clad polyimide laminate.

[0034] Labeling explanation: 1-Ultrafast laser source, 2-Time domain stretching module, 3-Wavelength compression module, 4-Processing head system, 5-Laminated sample to be processed, 6-Load-bearing and motion system. Detailed Implementation

[0035] The present application will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0036] Figure 1 This illustration shows a schematic diagram of a laser processing equipment for laminated materials according to an embodiment of this application. The laser processing equipment may include an ultrafast laser source 1, a time-domain stretching module 2, a wavelength compression module 3, a processing head system 4, and a support and motion system 6. The time-domain stretching module 2 can perform time-domain shaping on the laser emitted from the ultrafast laser source 1, used to shape the wavelength for each duration while maintaining a constant total energy. t A single pulse of 0 is broadened in the time domain, such that the total duration of the broadened time domain envelope is... t p , t p >t0. Wavelength compression module 3 can be used to compress the laser wavelength, ensuring that the center wavelength λ after wavelength transformation meets the requirements. The laminated sample 5 to be processed can be placed on the support and motion system 6. The laser output from wavelength compression module 3 can be applied to the laminated sample 5 by the processing head system 4 to achieve laser processing of the laminated material.

[0037] Figure 2 A schematic flowchart of a laser selective etching method for laminated materials provided in an embodiment of this application is shown.

[0038] Step 1: Using time-domain shaping techniques, the duration of each pulse in the ultrafast laser near-infrared single-pulse sequence in its intrinsic state is... t A single pulse with a value of 0 is time-domain broadened while keeping the total energy constant, such that the total duration after broadening is... t p, t p >t0.

[0039] Specifically, the ultrafast laser source 1 of the laser processing equipment is turned on, and the relative positions and orientations of the various components of the processing system are adjusted. After the pulses emitted by the ultrafast laser source 1 are time-domain shaped, each single pulse in the original single pulse sequence is broadened and input into the wavelength compression module 3.

[0040] The broadened temporal envelope can include one or more sub-pulses. The interval between two adjacent temporal envelopes can correspond to the time repetition frequency. f The interval between two adjacent time-domain envelopes can be on the order of μm. When the time-domain envelope includes multiple sub-pulses, the interval between two adjacent sub-pulses can be on the order of fs or ps. The interval between two adjacent sub-pulses can also be the interval between the peak values ​​of two adjacent sub-pulses.

[0041] Total duration is t p The value of can be related to the shape of the pulse width expansion. The shape of the pulse width expansion can include, for example, an increasing envelope, a decreasing envelope, and a multiple envelope. An increasing envelope can refer to multiple sub-pulses in the envelope whose energy gradually increases in the time domain. A decreasing envelope can refer to multiple sub-pulses in the envelope whose energy gradually decreases in the time domain. A multiple envelope can refer to multiple sub-pulses in the envelope whose energy is approximately the same in the time domain. In some embodiments, for a decreasing envelope, the total duration of the expanded pulse is . t p It can tend to approach a larger total duration. t p End value; for multiple pregnancy envelope, the total duration of the broadened pulse is t p It can tend to approach a smaller total duration. t p End value.

[0042] In some embodiments, the laser center wavelength of the ultrafast laser near-infrared single-pulse sequence in step 1 is between 780 nm and 2000 nm, and the duration of a single pulse is... t 0 is a value ranging from 5fs to 2000fs based on half-height and full width.

[0043] In some embodiments, the total duration after stretching in step 1 t p The value range is 2.0ps to 1000ps, for example, 2.0ps to 20ps. The total duration after stretching is... t pThe pulse includes the following forms: containing ≥2 sub-pulses and the total duration from the start of the first sub-pulse to the end of the last sub-pulse is [duration missing]. t p It contains only one pulse and its duration is measured in half-width at half maximum (FWHM). t p The situation.

[0044] Step 2: Using laser frequency domain shaping techniques, the wavelength of the beam generated in Step 1 is transformed so that its center wavelength is λ.

[0045] Specifically, the wavelength compression module 3 can be used to compress the wavelength of the laser so that the value of the center wavelength λ after wavelength transformation meets the requirements.

[0046] In some embodiments, the center wavelength λ of the beam after wavelength conversion in step 2 is in the range of 650nm~430nm.

[0047] Step 3: Using the beam generated in Step 2 and focusing it, measure the equivalent pulse number of the dielectric-conductive composite material to be processed. N The dielectric material removal energy threshold at that time F th_1 and the energy threshold for removing conductive materials F th_2 .

[0048] Specifically, the beam generated in step 2 is guided into a condenser lens. For the "dielectric layer-conductive layer" type composite material to be processed, the beam speed relative to the workpiece is considered. v Pulse time repetition frequency f Information such as spot diameter is used to calculate the equivalent pulse number at each spot position. N The equivalent pulse number was determined using the area extrapolation method. N The energy removal threshold of dielectric materials below F th_1 Energy removal threshold of conductive layer material F th_2 .

[0049] In some embodiments, when the focused spot in step 3 is an elliptical or circular Gaussian spot, the equivalent pulse number is... N Estimate using the following formula:

[0050]

[0051] in, The equivalent number of pulses along the direction of the relative velocity between the beam and the workpiece. To focus the characteristic diameter of the elliptical light spot in this direction, the light intensity attenuation from the center of the spot is 1 / e of the intensity at the center of the spot.2 The required extension is twice the diameter; The equivalent number of pulses is perpendicular to the direction of relative motion between the beam and the workpiece. To focus the characteristic size of the elliptical spot in this direction, the light intensity attenuation from the center of the spot is 1 / e of the intensity at the center of the spot. 2 The required extension is twice the diameter; v The velocity of the light beam relative to the workpiece. f The total duration is t p The time repetition frequency between each time domain envelope, L To be parallel to the velocity v The distance between adjacent fill trajectories in the direction. Specifically, when... L =0, meaning there are no adjacent filled trajectories and only one trajectories along the velocity. v When machining the trajectory in the direction, ;when The time indicates that the focused beam is a Gaussian beam that is a perfect circle.

[0052] When the focused spot in step 3 is another type of spot, the equivalent pulse number is estimated according to the conventional algorithm in the field. N。

[0053] Step 4: Apply a laser pulse to the conductive layer side of the laminate material to be processed, using a pulse larger than [value missing]. F th_2 and less than F th_1 The pulse energy, using the equivalent number of pulses is N The processing parameters are selected, and the depth of the conductive layer is processed to the interface between the conductive material film and the dielectric.

[0054] The laminate to be processed is a material composed of a dielectric layer and a conductive layer. In some embodiments, the dielectric layer is made of a material with a conductivity of not more than 10 at room temperature (25°C). -11 S / m single-component materials or composite materials, the conductive layer is a metal or metal-like film layer with a total thickness of 0.2μm to 200μm, the film material includes copper and its alloys, gold and its alloys, aluminum and its alloys, silver and its alloys, nickel and its alloys, platinum and its alloys, chromium and its alloys, as well as metal films and graphitized carbon composed of different types of these metals (including their alloys) in pairs.

[0055] In one embodiment, the material being processed is a copper-plated polyimide film. The polyimide material has a room temperature conductivity of no more than 10 at 25°C. -11The insulating material has a thickness of 2.0 μm and its properties are close to those of pure copper. To ensure strong adhesion between the copper layer and the polyimide film, the surface of the polyimide film was subjected to plasma treatment to roughen the surface before copper plating. This resulted in 0.5 μm to 1 μm synapses embedded within the polyimide film beneath the 2.0 μm thick copper layer. These synapses originated from the pits left by the roughened polyimide surface roughness for the copper plating layer.

[0056] The following is a specific example illustrating a laser selective etching method for laminated materials provided in this application.

[0057] The laser emits light at a center wavelength of 1030 nm and can generate a single-pulse sequence with a duration of 300 fs and an adjustable frequency of 0.1 MHz to 2 MHz, with a maximum single-pulse energy of 1 mJ. The mirrors and transmission mirrors used in the processing system are dual-wavelength optical lenses adapted to 1030 nm and its frequency-doubled 515 nm wavelength.

[0058] First, the light pulses emitted by the laser are subjected to time-domain broadening shaping. Figure 1 The time-domain stretching module 2 shown is a self-made time-domain shaping module based on the principle of multi-film interference. It can split a single pulse with a duration of 300 fs into four sub-pulse envelopes on the time axis, each separated by 1.0 ps, ​​with an energy ratio of approximately 4:2:1:0.5 and a duration of approximately 500 fs for each sub-pulse. Therefore, the total duration of each four-pulse envelope is... t p ≈3.5ps.

[0059] Next, wavelength compression is performed on the laser. The input beam from the previous step is then guided... Figure 1 The wavelength compression module 3 shown is a module that can frequency double a 1030nm wavelength laser to 515nm.

[0060] Next, the 515nm green light input from the previous step is guided into the scanning galvanometer head, equipping it for processing. The parameter considered is the velocity of the light beam relative to the material being processed. v =2m / s, pulse time repetition frequency f =1.0MHz, near-circular focused spot diameter =15μm ("1 / e" 2 "Spot diameter definition", straight-line distance between adjacent filling trajectories L =2μm, that is , can be obtained N≈22. Using the well-known area epitaxy method, the material removal energy thresholds of the polyimide film and copper material under 22 equivalent pulses were measured as follows: F th_1 =0.15 J / cm 2 and F th_2 =1.0 J / cm 2 .

[0061] Finally, the copper-plated polyimide film workpiece to be processed is positioned so that the copper film side faces the normally incident laser pulse, using a laser pulse of 0.5 J / cm². 2 The pulse energy is used for processing, and other processing parameters, such as beam scanning speed, are also used. v Pulse time repetition frequency f、 Fill Spacing L The same procedure was followed as before regarding the spot diameter. After 50 etch passes over the copper film area, it was found that the copper film layer could be removed relatively cleanly, while the polyimide film layer remained undamaged. Figure 3 After 20 more cycles of etching with the same parameters, the polyimide film showed no significant changes, with no signs of ablation or blackening.

[0062] In contrast, remove Figure 1 The time-domain stretching module 2 and wavelength compression module 3 in the model, which utilize only the intrinsic time-domain and frequency-domain characteristics of femtosecond lasers (i.e., near-infrared femtosecond single-pulse sequences with a center wavelength of 1030 nm and a single pulse duration of 300 fs), are used to conduct similar experiments on the same material, still considering an equivalent number of 22 pulses and a pulse repetition frequency of [missing information]. f The case is 1.0 MHz, and several pulses with different energy fluxes are considered—from 1.5 J / cm². 2 Up to 3.0 J / cm 2 Unequal. It was found that even before etching reached the copper-polyimide interface, obvious scorching of the polyimide film had already occurred. (See...) Figure 4 After measuring the removal energy thresholds of the two materials, it was found that copper at this threshold was [value missing]. F th_1 =1.6 J / cm 2 Polyimide is F th_2 =0.8J / cm 2 It can be seen that, compared with the laser scalpel used for time-domain and frequency-domain co-shaping in the aforementioned experiment, the results are different. F th_1 =0.15 J / cm 2 and F th_2 =1.0 J / cm 2Compared to the previous method, when using non-temporal and frequency-domain co-shaping (i.e., using only the intrinsic emission characteristics of the laser), the copper removal threshold is much higher, reaching 1.6 J·cm⁻¹ after co-shaping in both the time and frequency domains of the laser scalpel. -2 / 0.15J·cm -2 =10.7 times, while the removal threshold of polyimide did not change significantly.

[0063] Table 1

[0064]

[0065] Therefore, by performing time-domain and frequency-domain synergistic shaping on traditional ultrafast lasers, the original situation of "high copper threshold and low polyimide threshold" will be reversed, becoming a favorable situation of "high polyimide threshold and low copper threshold," making it very easy to selectively remove copper without damaging the polyimide substrate.

[0066] In summary, by performing synergistic shaping in both the time and frequency domains using traditional ultrafast lasers, the relative relationship between the removal thresholds of the conductive and dielectric materials in the "conductive film-dielectric" material configuration can be altered. This directly solves the problem of precisely and non-destructively etching conductive patterns using traditional ultrafast lasers. Furthermore, the change in the processing threshold of copper before and after synergistic shaping in the time and frequency domains clearly shows that the removal threshold of copper decreases from 1.6 J / cm². 2 The temperature plummeted to 0.15 J / cm². 2 This results in the pulse energy required to etch copper increasing from >1.6 J / cm². 2 The temperature plummeted to 0.5 J / cm. 2 Therefore, although laser frequency domain shaping (i.e., wavelength compression) generally comes at the cost of losing about 40% of laser energy, the significant reduction in required pulse energy means that this energy loss not only does not reduce processing efficiency but also greatly improves it due to high energy utilization. The present invention provides a laser selective material removal method and laser processing equipment for laminated materials. This method is a selective removal of conductive materials from the surface of dielectric layers and the formation of conductive patterns. It requires only the addition of a few mature or simple modules and is highly compatible with existing industrial ultrafast laser processing equipment. It is a precise, simple, and easy-to-implement method.

[0067] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope defined in the claims of the present invention.

Claims

1. A method for selective laser etching of laminated materials, characterized in that, include: Using time-domain shaping techniques, the duration of each pulse in an ultrafast laser near-infrared single-pulse sequence in its intrinsic state is... t A single pulse with a value of 0 is time-domain broadened while keeping the total energy constant, such that the total duration after broadening is... t p , t p >t0; By using laser frequency domain shaping techniques, the wavelength of the broadened beam is transformed so that its center wavelength is λ. By using a wavelength-converted and focused beam, the equivalent pulse number is measured for the laminated materials to be processed. N The dielectric material removal energy threshold at that time F th_1 and the energy threshold for removing conductive materials F th_2 The laminated material to be processed is a dielectric layer-conductive layer composite material; A laser pulse is applied to one side of the conductive layer of the laminate material to be processed, using a pulse larger than [missing value]. F th_2 and less than F th_1 The pulse energy, using the equivalent number of pulses is N The processing parameters are selected to process the conductive layer to the interface between the conductive material film and the dielectric. When the focused spot is an elliptical or circular Gaussian spot, the equivalent pulse number N satisfy: in, The equivalent number of pulses along the direction of the relative velocity between the beam and the workpiece. To focus the characteristic diameter of the elliptical light spot in this direction, the light intensity attenuation from the center of the spot is 1 / e of the intensity at the center of the spot. 2 The required extension is twice the diameter; The equivalent number of pulses is perpendicular to the direction of relative motion between the beam and the workpiece. To focus the characteristic size of the elliptical spot in this direction, the light intensity attenuation from the center of the spot is 1 / e of the intensity at the center of the spot. 2 The required extension is twice the diameter; v The velocity of the light beam relative to the workpiece. f The total duration is t p The time repetition frequency between each time domain envelope and the time domain envelope. L To be parallel to the velocity v The distance between adjacent fill trajectories in the direction; when L =0, meaning there are no adjacent filled trajectories and only one trajectories along the velocity. v When machining the trajectory in the direction, ;when The time indicates that the focused beam is a Gaussian beam that is a perfect circle.

2. The method according to claim 1, characterized in that, The dielectric layer is made of a material with a conductivity of no more than 10 at room temperature (25°C). -11 The single-component material or composite material with a S / m, wherein the conductive layer is a metal or metal-like film with a total thickness of 0.2μm to 200μm.

3. The method according to claim 2, characterized in that, The material being processed is a copper-plated polyimide film with a copper plating layer thickness of 2.0 μm. Before copper plating, the surface of the polyimide film is subjected to plasma treatment to roughen the surface, so that synapses of 0.5 μm to 1 μm are embedded in the polyimide film under the copper film.

4. The method according to claim 1, characterized in that, The center wavelength of ultrafast near-infrared single-pulse laser sequences is between 780 nm and 2000 nm, and the duration of a single pulse is... t 0 is a value ranging from 5fs to 2000fs based on half-height and full width.

5. The method according to claim 1, characterized in that, Total duration after expansion t p The value ranges from 2.0ps to 1000ps, and the total duration after stretching is... t p The pulse includes any of the following forms: containing ≥2 sub-pulses and with a total duration from the start of the first sub-pulse to the end of the last sub-pulse of . t p It contains only one pulse and its duration is measured in half-width at half maximum (FWHM). t p The situation.

6. The method according to claim 1, characterized in that, The center wavelength λ of the beam after wavelength conversion ranges from 650nm to 430nm.

Images