A method for processing surface microstructure of laminated ceramic substrate

Abstract

The present invention relates to a method for processing the surface microstructure of a laminated ceramic substrate. The method comprises: irradiating the laminated ceramic substrate with a laser beam, controlling the depth of the laser modified area on the laminated ceramic substrate, and generating an active metamorphic layer; adding a chemical liquid to remove the active metamorphic layer; repeatedly and alternately removing the residual ceramic substrate by a laser beam and chemical milling, and predicting the size and surface quality of the residual ceramic substrate by a laser-chemical milling model until the rough processing of the residual ceramic substrate reaches the expected value of the depth and surface roughness; adjusting the laser processing parameters and the chemical milling parameters again for local removal, and determining the laminated ceramic substrate after local removal; using a micro-milling machine and a micro-milling cutter to perform fine processing on the processing area at a set feed speed, and determining the laminated ceramic substrate after fine processing. The present invention can avoid the situation where ceramics are broken and fractured, and improve the processing efficiency.

Description

Technical Field

[0001] The invention relates to the field of ceramic processing, in particular to a method for processing a surface microstructure of a laminated ceramic substrate. Background Art

[0002] Functional ceramics are a new type of ceramic material with excellent comprehensive performance. They have a series of excellent characteristics such as excellent thermal conductivity, reliable electrical insulation, low dielectric constant and dielectric loss, non-toxicity, and a thermal expansion system that matches silicon. They are considered to be ideal materials for the new generation of highly integrated semiconductor substrates and electronic device packaging, and have attracted widespread attention from researchers at home and abroad. Laminated ceramic substrates are commonly used materials in the field of chip packaging, but due to the increase in electronic integration and chip power, there is an urgent need to process microchannels on the substrate for heat dissipation. Mechanical processing is still considered to be the most reliable and ideal processing method, which can meet the requirements of high dimensional accuracy and high surface finish of finished products. However, for ceramics with extremely high hardness, since they are typical difficult-to-process materials, traditional mechanical processing can easily cause the ceramic thin layer to break and crack, and the processing efficiency is low. Summary of the invention

[0003] The purpose of the present invention is to provide a method for processing the surface microstructure of a laminated ceramic substrate to solve the problems that traditional mechanical processing easily causes breakage and cracks in the ceramic thin layer and has low processing efficiency.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] A method for processing a surface microstructure of a laminated ceramic substrate, comprising:

[0006] The laminated ceramic substrate is irradiated with a laser beam, and laser processing parameters are set, auxiliary gas is added, and the depth of the laser modified area on the laminated ceramic substrate is controlled to generate an active metamorphic layer; the laser processing parameters include power, spot diameter, laser scanning interval and laser scanning speed;

[0007] Adding chemical liquid so that the active metamorphic layer reacts with the chemical liquid to remove the active metamorphic layer;

[0008] The residual ceramic substrate is removed by repeatedly and alternately using a laser beam and chemical milling, and the size and surface quality of the residual ceramic substrate are predicted using a laser-chemical milling model until the rough machining of the residual ceramic substrate reaches the expected values ​​of depth and surface roughness; the residual ceramic substrate is a layer of ceramic substrate remaining after the active metamorphic layer is removed;

[0009] When the expected values ​​of the depth and the surface roughness are reached, the laser processing parameters and the chemical milling parameters are adjusted again to perform local removal, and the laminated ceramic substrate after the local removal is determined; the chemical milling parameters include temperature and reaction time;

[0010] The area to be processed in the laminated ceramic substrate after the partial removal is finely processed by using a milling machine smaller than a set size and a milling cutter smaller than a set size at a set feed speed to determine the finely processed laminated ceramic substrate.

[0011] Optionally, the laser beam is a Gaussian pulse laser, and the propagation of the Gaussian pulse laser in space follows Kirchhoff's formula.

[0012] Optionally, the method of irradiating the laminated ceramic substrate with a laser beam, setting laser processing parameters, adding auxiliary gas, and controlling the depth of the laser modified area on the laminated ceramic substrate to generate an active metamorphic layer may also include:

[0013] Before processing the laminated ceramic substrate, a leveling treatment is performed using an electronic level, and the surface of the laminated ceramic substrate is wiped with degreased alcohol cotton.

[0014] Optionally, the adding of chemical liquid so that the active metamorphic layer reacts with the chemical liquid and the active metamorphic layer is removed, and then the method further comprises:

[0015] According to the formula And the formula Q i，j =Q(xi×Δx,yj×Δy) to construct the laser-chemical milling model;

[0016] Among them, Q sum (x, y) is the energy density after laser surface etching energy superposition; m is the number of scanning intervals between the position with the lowest energy superposition effect and the center of the light spot in the X direction; n is the number of scanning intervals between the position with the lowest energy superposition effect and the center of the light spot in the Y direction; Q i,j It is the energy density value at the point i×Δx, j×Δy away from the center of the spot (x, y), where Δx is the distance between adjacent pulses in the laser scanning direction, and Δy is the laser scanning distance.

[0017] Optionally, the residual ceramic substrate is removed alternately by laser beam and chemical milling, and the size and surface quality of the residual ceramic substrate are predicted by a laser-chemical milling model until the rough machining of the residual ceramic substrate reaches expected values ​​of depth and surface roughness, specifically including:

[0018] When laser processing is repeated, the scanning speed is adjusted according to the laser-chemical milling model, and the laser energy density value and the average deviation of the laser energy density are determined;

[0019] According to the fitting relationship between the laser energy density value and the thickness of the active metamorphic layer and the fitting relationship between the average deviation of the laser energy density and the surface roughness after laser-chemical milling, the size and surface quality of the residual ceramic substrate produced by the laser-induced reduction reaction are predicted and controlled until the rough processing of the residual ceramic substrate reaches the expected values ​​of depth and surface roughness.

[0020] Optionally, the residual ceramic substrate is removed alternately by laser beam and chemical milling, and the size and surface quality of the residual ceramic substrate are predicted by a laser-chemical milling model until the rough machining of the residual ceramic substrate reaches the expected values ​​of depth and surface roughness; the residual ceramic substrate is a layer of ceramic substrate remaining after the active metamorphic layer is removed, and then further includes:

[0021] Introducing the average deviation of laser energy density R Q The concept of predicting the surface roughness value after processing;

[0022] in, is the average value of laser energy density, and S is the sampling area.

[0023] Optionally, the method further comprises: using a milling machine smaller than a set size and a milling cutter smaller than a set size to perform finish machining on the to-be-machined area in the laminated ceramic substrate after the partial removal at a set feed speed, and determining the laminated ceramic substrate after finish machining; and then further comprising:

[0024] The processed laminated ceramic substrate was cleaned for 15 minutes using an ultrasonic cleaner and then wiped dry with a non-woven fabric.

[0025] Optionally, the spot diameter of the laser beam is kept constant, and the lens height of the laser is adjusted each time before the laser induces the laminated ceramic substrate to produce an active metal layer, so as to refocus the laser beam.

[0026] Optionally, it also includes: microscopically observing the multilayer ceramic substrate imaging system during the processing through an imaging system; the imaging system is an auxiliary positioning imaging system with a resolution higher than a set threshold.

[0027] Optionally, the chemical liquid is a hydrochloric acid solution.

[0028] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects: the present invention discloses a method for processing the surface microstructure of a laminated ceramic substrate, inducing a reduction reaction on the ceramic surface through laser irradiation to produce an active metamorphic layer, and using the chemical difference between the ceramic material and the active metamorphic layer to achieve rapid removal by chemical milling, laser and chemical milling are performed alternately to achieve rough processing, and finally a micro-milling cutter is used to control the shape of the microstructure through a single feed.

[0029] At the same time, chemical milling is used to remove the active metamorphic layer of the residual ceramic substrate, which not only reduces the wear of the tool, but also avoids the products of laser irradiation on the ceramic surface adhering to the substrate surface, resulting in a decrease in the subsequent laser processing accuracy, and reduces the subsequent cleaning process.

[0030] Compared with conventional mechanical processing methods, the rough processing method combining laser and chemical milling greatly improves the processing efficiency of laminated ceramic substrates and reduces production costs. Chemical milling of the active metamorphic layer formed after laser modification can not only increase the amount of material removed per unit time, but also effectively reduce the thin layer breakage of the laminated ceramic substrate and the internal cracks of the parts during the processing. At the same time, auxiliary gas is added during the processing, making it difficult for the oxidized material to produce an active metal metamorphic layer during the laser processing, avoiding the breakage and fracture of the ceramic. After reaching the rough processing size requirements, the laminated ceramic substrate is finely processed using a micro-milling machine to improve the shape accuracy and structural integrity of the parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 A flow chart of a method for processing the surface microstructure of a laminated ceramic substrate provided by the present invention;

[0033] Figure 2 A schematic diagram of a processing device for the surface microstructure of a laminated AlN substrate provided by the present invention;

[0034] Figure 3 Based on Figure 2 Flow chart of the processing method of the processing device. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] The purpose of the present invention is to provide a method for processing the surface microstructure of a laminated ceramic substrate, which can avoid the ceramic from being broken and fractured, and improve the processing efficiency.

[0037] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] Figure 1 The flowchart of the method for processing the surface microstructure of the laminated ceramic substrate provided by the present invention is as follows: Figure 1 As shown, a method for processing the surface microstructure of a laminated ceramic substrate comprises:

[0039] Step 101: irradiate the laminated ceramic substrate with a laser beam, set laser processing parameters, add auxiliary gas, control the depth of the laser modified area on the laminated ceramic substrate, and produce an active metamorphic layer; the laser processing parameters include power, spot diameter, laser scanning interval and laser scanning speed; the auxiliary gas is an inert gas, such as argon, helium, etc.

[0040] Before step 101, the method further includes: performing a leveling process using an electronic level before processing the laminated ceramic substrate, and wiping the surface of the laminated ceramic substrate with degreased alcohol cotton.

[0041] The laser beam is a Gaussian pulse laser, and the propagation of the Gaussian pulse laser in space follows Kirchhoff's formula.

[0042] Step 102: Add chemical liquid to make the active deteriorated layer react with the chemical liquid to remove the active deteriorated layer. The chemical liquid is a hydrochloric acid solution.

[0043] After step 102, the following steps are further included:

[0044] According to the formula And the formula Q i，j =Q(xi×Δx, yj×Δy) to construct the laser-chemical milling model; where Q sum (x, y) is the energy density after laser surface etching energy superposition; m is the number of scanning intervals between the position with the lowest energy superposition effect and the center of the light spot in the X direction; n is the number of scanning intervals between the position with the lowest energy superposition effect and the center of the light spot in the Y direction; Q i,j It is the energy density value at the point i×Δx, j×Δy away from the center of the spot (x, y), where Δx is the distance between adjacent pulses in the laser scanning direction, and Δy is the laser scanning distance.

[0045] Step 103: The residual active metamorphic layer is removed repeatedly and alternately by laser beam and chemical milling, and the size and surface quality of the residual ceramic substrate are predicted by a laser-chemical milling model until the rough machining of the residual ceramic substrate reaches the expected values ​​of depth and surface roughness; the residual ceramic substrate is a ceramic substrate layer remaining after the active metamorphic layer is removed.

[0046] The step 103 specifically includes: when repeating the laser processing, adjusting the scanning speed according to the laser-chemical milling model, determining the laser energy density value and the average deviation of the laser energy density; determining a fitting relationship according to the laser energy density value and the average deviation of the laser energy density; and predicting and controlling the size and surface quality of the residual ceramic substrate produced by the laser-induced reduction reaction according to the fitting relationship until the rough processing of the residual ceramic substrate reaches the expected values ​​of depth and surface roughness.

[0047] After step 103, the following steps are further included:

[0048] Introducing the average deviation of laser energy density R Q The concept of predicting the surface roughness value after processing; among them, is the average value of laser energy density, and S is the sampling area.

[0049] Step 104: When the expected values ​​of the depth and surface roughness are reached, the laser processing parameters and the chemical milling parameters are adjusted again to perform local removal, and the laminated ceramic substrate after the local removal is determined; the chemical milling parameters include temperature and reaction time.

[0050] Step 105: using a milling machine smaller than a set size and a milling cutter smaller than a set size to perform finish machining on the to-be-machined area of ​​the laminated ceramic substrate after the partial removal at a set feed speed, and determining the finished laminated ceramic substrate.

[0051] After step 105, the method further includes: using an ultrasonic cleaning machine to clean the processed laminated ceramic substrate for 15 minutes, and wiping it dry with a non-woven fabric.

[0052] The present invention also includes: an imaging system for microscopically observing the laminated ceramic substrate during processing through an imaging system; the imaging system is an auxiliary positioning imaging system with a resolution higher than a set threshold.

[0053] The spot diameter of the laser beam is kept constant, and the lens height of the laser is adjusted each time before the laser induces the laminated ceramic substrate to produce an active metamorphic layer, so as to refocus the laser beam.

[0054] The present invention is applied to the actual processing process of the surface microstructure of the laminated aluminum nitride AlN substrate. Figure 2 It is a schematic diagram of a processing device for the surface microstructure of a laminated AlN substrate provided by the present invention, Figure 3 Based on Figure 2 Processing method flow chart of the processing device, such as Figure 2-Figure 3 As shown, the device includes: a CCD microscope 1; a micro-milling machine 2; an air spindle 3; a laser 4; a nanosecond laser beam 5; a control system 6; a micro-milling cutter 7; an air-liquid nozzle 8; a processing platform 9; a micro-milling machine X-axis servo mechanism 10; a micro-milling machine Y-axis servo mechanism 11; and a container 12.

[0055] The method includes:

[0056] Step 1: Clamp the laminated AlN substrate into the inner cavity of the base container.

[0057] Step 2: According to the fitting relationship between the laser energy density value and the laser ablation depth, the laser power is set to 20 W, the spot diameter is 50 μm, the laser scanning interval is 2 μm, and the laser scanning speed is 5 mm / s. Under this set of parameters, the area to be processed of the laminated AlN substrate is pre-treated to cause a reduction reaction, and it is predicted that an active metamorphic layer with a thickness of about 330 μm will be produced.

[0058] Step 3: Add 20% hydrochloric acid solution by mass into the base container, assemble the cover plate, and soak the activated plate in the hydrochloric acid solution for 30 minutes to remove the active degenerate layer on the surface.

[0059] When other parameters remain unchanged, according to the relationship between the average laser energy density and the laser ablation depth, the laser scanning speed is adjusted to 6mm / s, and the active metamorphic layer with a thickness of about 300μm is predicted. When the scanning speed is 7mm / s, the thickness of the active metamorphic layer is predicted to be about 250μm. The scanning speeds are adjusted to 6mm / s and 7mm / s respectively, and steps 2 to 3 are repeated until the rough processing size is reached. The actual total depth of laser processing is measured to be 890μm.

[0060] Step 4: Move the platform, open the cover plate, set the tool overlap to 50%, add cutting fluid, and use a micro-milling machine and a micro-milling cutter to micro-process the area to be processed of the laminated AlN substrate at a cutting depth of 10 μm and a feed speed of 200 mm / min. Finishing is achieved through one feed movement, so that the total processing depth reaches 900 μm.

[0061] Step 5: Use an ultrasonic cleaner to clean the processed workpiece.

[0062] As a preferred implementation of this embodiment, the laminated AlN substrate can be leveled by an electronic level before processing, and the surface can be wiped with degreased alcohol cotton.

[0063] In this embodiment, the spot diameter of the laser should always be kept constant, and before each activation process, the height of the laser lens should be adjusted to refocus the laser.

[0064] As an implementation of this embodiment, the cutting fluid in step 4 can be distilled water or alcohol. Using alcohol as the cutting fluid can achieve the effect of lubrication and cooling while discharging chips.

[0065] The present invention realizes surface modification of laminated AlN substrate by laser activation, that is, utilizing the thermal effect of laser to make the surface of laminated AlN substrate undergo reduction reaction to realize thermal decomposition, and directly generates a metamorphic layer with more active chemical properties. The method has the advantages of low cost, high efficiency, and simple equipment maintenance. A laser energy distribution model is established, and the laser energy density value Q is used to calculate the surface modification of laminated AlN substrate. sum The fitting relationship between (x, y) and the thickness of the active metamorphic layer is used to predict and control the laser chemical milling depth, and the average deviation of the laser energy density R is introduced. Q The concept of chemical milling is used to predict the relationship between the surface roughness of the etched groove after laser chemical milling and the laser energy density; chemical milling of the metamorphic layer formed after laser modification can not only increase the material removal per unit time, but also effectively reduce the AlN thin layer breakage phenomenon and internal cracks of the parts during the processing; due to the high integration of laser and chemical milling assisted micro-milling processing equipment, it can not only improve the surface processing quality, making the surface roughness Ra value after processing decrease by about 12%, but also improve the processing efficiency, reduce tool wear, shorten the processing cycle by 70%, and reduce the cost by about 75%.

[0066] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0067] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for processing a surface microstructure of a laminated ceramic substrate, characterized in that: include: The laminated ceramic substrate is irradiated with a laser beam, and laser processing parameters are set, auxiliary gas is added, and the depth of the laser modified area on the laminated ceramic substrate is controlled to generate an active metamorphic layer; the laser processing parameters include power, spot diameter, laser scanning interval and laser scanning speed; Adding a chemical liquid so that the active metamorphic layer reacts with the chemical liquid to remove the active metamorphic layer; the chemical liquid is a hydrochloric acid solution; According to the formula And the formula Q i,j =Q(xi×Δx,yj×Δy) to construct the laser-chemical milling model; Among them, Q sum (x, y) is the energy density after laser surface etching energy superposition; m is the number of scanning intervals between the position with the lowest energy superposition effect and the center of the light spot in the X direction; n is the number of scanning intervals between the position with the lowest energy superposition effect and the center of the light spot in the Y direction; Q i,j is the energy density value at the spot at a distance i×Δx, j×Δy from the spot center (x, y), where Δx is the distance between adjacent pulses in the laser scanning direction, and Δy is the laser scanning distance; The residual ceramic substrate is removed by repeatedly alternating laser beam and chemical milling, and the size and surface quality of the residual ceramic substrate are predicted by a laser-chemical milling model until the rough machining of the residual ceramic substrate reaches the expected values ​​of depth and surface roughness, specifically including: When laser processing is repeated, the scanning speed is adjusted according to the laser-chemical milling model, and the laser energy density value and the average deviation of the laser energy density are determined; According to the fitting relationship between the laser energy density value and the thickness of the active metamorphic layer and the fitting relationship between the average deviation of the laser energy density and the surface roughness after laser-chemical milling, the size and surface quality of the residual ceramic substrate produced by the laser-induced reduction reaction are predicted and controlled until the rough processing of the residual ceramic substrate reaches the expected value of the depth and surface roughness; the residual ceramic substrate is a layer of ceramic substrate remaining after the active metamorphic layer is removed; Introducing the average deviation of laser energy density R Q The concept of predicting the surface roughness value after processing; among them, is the average value of laser energy density, S is the sampling area When the expected values ​​of the depth and the surface roughness are reached, the laser processing parameters and the chemical milling parameters are adjusted again to perform local removal, and the laminated ceramic substrate after the local removal is determined; the chemical milling parameters include temperature and reaction time; Using a milling machine smaller than a set size and a milling cutter smaller than a set size at a set feed speed to finish-process the area to be processed in the laminated ceramic substrate after the partial removal, and determining the laminated ceramic substrate after finishing; The method includes: Step 1: clamping the laminated AlN substrate in the inner cavity of the base container; Step 2: according to the fitting relationship between the laser energy density value and the laser ablation depth, the laser power is set to 20 W, the spot diameter is set to 50 μm, the laser scanning interval is set to 2 μm, and the laser scanning speed is set to 5 mm / s. Under this set of parameters, the area to be processed of the laminated AlN substrate is pre-treated to cause a reduction reaction, and an active metamorphic layer with a thickness of about 330 μm is predicted to be generated; Step 3: Add a 20% hydrochloric acid solution into the base container, assemble the cover plate, and soak the activated plate in the hydrochloric acid solution for 30 minutes to remove the active deteriorated layer on the surface; When other parameters remain unchanged, according to the relationship between the average laser energy density and the laser ablation depth, the laser scanning speed is adjusted to 6 mm / s, and the active metamorphic layer with a thickness of about 300 μm is predicted; when the scanning speed is 7 mm / s, the thickness of the active metamorphic layer is predicted to be about 250 μm; the scanning speed is adjusted to 6 mm / s and 7 mm / s respectively, and steps 2 to 3 are repeated until the rough processing size is reached. The actual total depth of laser processing is measured to be 890 μm; Step 4: Move the platform, open the cover plate, set the tool overlap to 50%, add cutting fluid, and use a micro-milling machine and a micro-milling cutter to perform micro-machining on the to-be-processed area of ​​the laminated AlN substrate at a cutting depth of 10 μm and a feed speed of 200 mm / min, and achieve fine machining through one feed motion, so that the total machining depth reaches 900 μm; Step 5: Use an ultrasonic cleaner to clean the processed workpiece.

2. The method for processing the surface microstructure of a multilayer ceramic substrate according to claim 1, characterized in that: The laser beam is a Gaussian pulse laser, and the propagation of the Gaussian pulse laser in space follows Kirchhoff's formula.

3. The method for processing the surface microstructure of a multilayer ceramic substrate according to claim 2, characterized in that: The method comprises: irradiating the laminated ceramic substrate with a laser beam, setting laser processing parameters, adding auxiliary gas, controlling the depth of the laser modified area on the laminated ceramic substrate, and generating an active metamorphic layer. The method further comprises: Before processing the laminated ceramic substrate, a leveling treatment is performed using an electronic level, and the surface of the laminated ceramic substrate is wiped with degreased alcohol cotton.

4. The method for processing the surface microstructure of a multilayer ceramic substrate according to any one of claims 1 to 3, characterized in that: The method further comprises: using a milling machine smaller than a set size and a milling cutter smaller than a set size to perform finish machining on the to-be-machined area of ​​the laminated ceramic substrate after the partial removal at a set feed speed, and determining the laminated ceramic substrate after the finish machining, and then further comprising: The processed laminated ceramic substrate was cleaned for 15 minutes using an ultrasonic cleaner and then wiped dry with a non-woven fabric.

5. The method for processing the surface microstructure of a multilayer ceramic substrate according to claim 4, characterized in that: The spot diameter of the laser beam is kept constant, and the lens height of the laser is adjusted each time before the laser induces the laminated ceramic substrate to produce an active metal layer, so as to refocus the laser beam.

6. The method for processing the surface microstructure of a multilayer ceramic substrate according to claim 4, characterized in that: Also includes: The imaging system is used to microscopically observe the multilayer ceramic substrate imaging system during the processing; the imaging system is an auxiliary positioning imaging system with a resolution higher than a set threshold.

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