Electrolyte solution based on etching constraint system and method for making micro-holes in liquid crystal polymer substrate

Abstract

The application discloses an electrolyte solution based on an etching restraint system, which is used for etching a copper layer and a liquid crystal polymer layer of a liquid crystal polymer substrate and forming micropores; the electrolyte solution comprises an etchant precursor and a restraint agent; the electrolyte solution comprises a copper layer electrolyte solution and a liquid crystal polymer layer electrolyte solution which are used for etching the copper layer and the liquid crystal polymer layer respectively; the etchant precursor in the electrolyte solution of the copper layer is FeCl2, and the restraint agent is SnCl2; the etchant precursor in the electrolyte solution of the liquid crystal polymer layer is potassium manganate, and the restraint agent is hydrogen peroxide. The electrolyte solution based on the etching restraint system can be used for etching the copper layer and the LCP layer of the LCP flexible substrate based on the etching restraint technology, and can process micropores with small diameters and high depth-width ratios (10-15) on the LCP flexible substrate.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of PCB processing, and particularly relates to an electrolyte solution based on an etching constraint system and a method for manufacturing micro-holes of a liquid crystal polymer (LCP) flexible substrate by using the electrolyte solution. BACKGROUND

[0002] With the wireless communication entering the 5G era, from the communication network to the terminal application, the communication frequency is comprehensively high-frequency, high-speed and large-capacity, which puts forward more technical requirements such as higher frequency, smaller size, better heat resistance and more stable performance for flexible packaging substrates. Liquid crystal polymer (LCP) has the characteristics of easy bending, low dielectric loss, low moisture absorption, low thermal expansion coefficient and good chemical resistance, and is considered to be the best flexible packaging substrate material for realizing high-frequency and high-speed signal transmission.

[0003] Compared with traditional flexible substrate materials such as polyimide (PI), the melting point of LCP is lower, and the material is softer. The high temperature generated in the drilling process will directly affect the morphology of the hole and the interlayer peeling strength, and the hole manufacturing of the substrate is difficult. At present, the hole manufacturing methods of LCP flexible substrate mainly include mechanical drilling and laser drilling.

[0004] Among them, mechanical drilling uses tungsten steel drill bits of different diameters to drill holes. This method has high processing efficiency, good quality and low cost for holes with a diameter greater than 200 μm. Numerical control drilling machine can also manufacture holes with a diameter of 80 μm to 100 μm. However, as the hole diameter continues to decrease, mechanical drilling must adjust the drilling speed, feed amount and feed speed in order to remove drill chips and avoid heat accumulation in the hole. The drilling speed slows down, the production efficiency decreases, and the manufacturing cost increases exponentially. When the hole diameter is less than 50 μm, the production cost is too high, the process difficulty is too great, and it is not suitable for mass production of micro-holes.

[0005] Laser drilling is generally divided into infrared (CO2) laser drilling and ultraviolet (UV) laser drilling according to the form of the laser source. The principle of infrared laser drilling is photothermal ablation: the material to be processed absorbs high-energy laser, heats to melting in a very short time and is evaporated to form a hole. The principle of UV laser drilling is photochemical ablation: the high-energy photons (more than 2eV electron volts) in the ultraviolet region are absorbed, and when the absorbed energy is sufficient, the metal bonds of the copper foil and the covalent bonds of the resin are broken into ultra-fine particles and escape, thereby forming a micro-hole. However, as the size of the micro-hole continues to shrink and the aspect ratio continues to increase, heat accumulation occurs in the hole during laser drilling, causing problems such as micro-hole thermal melting and shrinkage. Therefore, the patent CN112074096A proposes an intermittent UV laser drilling method to reduce the "thermal damage" of the micro-hole. However, this method significantly reduces the micro-hole manufacturing efficiency; and to ensure that the laser focus does not shift and the focal length moves down by the same micro distance each time, the requirement for equipment precision is improved, and the production cost is increased.

[0006] With the continuous reduction in size and the continuous improvement in integration of electronic components, the diameter of LCP micro-holes continues to shrink, and the aspect ratio continues to increase. Due to the thermoplastic characteristics of LCP substrate materials, existing mechanical drilling and laser drilling methods have encountered bottlenecks and cannot effectively solve problems such as medium-conductor layer separation and thermal melting and shrinkage caused by heat accumulation during micro-hole manufacturing; the requirement for equipment precision is high, the production cost is high, and the production efficiency is low. Moreover, after drilling by the existing LCP micro-hole manufacturing method, drill dirt is left in the hole, and the hole wall needs to be cleaned and roughened before metalization. SUMMARY

[0007] Therefore, in order to overcome the defects of the prior art, the purpose of the present application is to provide an electrolyte solution based on an etching constraint system and a method for manufacturing micro-holes of a liquid crystal polymer (LCP) flexible substrate using the electrolyte solution.

[0008] In order to achieve the above purpose, the present application adopts the following technical solutions:

[0009] An electrolyte solution based on an etching constraint system, characterized in that the electrolyte solution is used to etch a copper layer and a liquid crystal polymer layer of a liquid crystal polymer substrate and form micro-holes; the electrolyte solution comprises an etchant precursor and a constraint agent; the electrolyte solution comprises a copper layer electrolyte solution and a liquid crystal polymer layer electrolyte solution for etching the copper layer and the liquid crystal polymer layer, respectively;

[0010] The etchant precursor in the electrolyte solution of the copper layer is FeCl2, and the constraint agent is SnCl2.

[0011] The etchant precursor in the electrolyte solution of the liquid crystal polymer layer is potassium permanganate, and the constraint agent is hydrogen peroxide. In actual use, a basic substance needs to be added to adjust the pH of the system, so that the potassium permanganate can play its role as an etchant precursor in the alkaline solution. The basic substance in some embodiments is selected as potassium hydroxide.

[0012] According to some preferred embodiments of the present application, the molar ratio of FeCl2 to SnCl2 in the electrolyte solution is 0.1-0.5:1, preferably 0.1-0.3:1, and in some embodiments, preferably 0.2:1.

[0013] According to some preferred embodiments of the present application, the electrolyte solution of the copper layer further comprises a complexing agent, and the molar concentration of the complexing agent in the electrolyte solution of the copper layer is 0.01-0.02 mol / L, preferably 0.01-0.015 mol / L, and in some embodiments, preferably 0.012 mol / L.

[0014] According to some preferred embodiments of the present application, the complexing agent is 2,2-bipyridine, and the electrolyte solution of the copper layer comprises HCl; the molar ratio of FeCl2, 2,2-bipyridine, SnCl2, and HCl is 0.1-0.3:0.03-0.09:1:0.5-1.5.

[0015] FeCl2 is selected as the etchant precursor, and the etchant FeCl3 is generated on the surface of the micro work electrode by electrochemical induction, as shown in formula 1.1. The etchant reacts with copper to etch the copper layer, as shown in formula 1.2. 2,2-bipyridine (bipy) is selected as the complexing agent to accelerate the etching speed. SnCl2 is selected as the constraint agent, which reacts with the etchant on the surface of the micro work electrode to limit the diffusion of the etchant, as shown in formula 1.3.

[0016] Fe 2+ -e=Fe 3+ (1.1)

[0017] 2Fe 3+ +Cu=2Fe 2+ +Cu 2+ (1.2)

[0018] S n 2+ +2[Fe(bipy)3] 3+ →S n 4+ +2[Fe(bipy)3]2+ (1.3)

[0019] In some embodiments, the etching-restricting system electrolyte solution for the copper layer is configured to include the following components at the following molar concentrations: 0.04 mol / L FeCl2, 0.012 mol / L bipy, 0.2 mol / L SnCl2, 0.2 mol / L HCl. The HCl provides an acidic environment and Cl for displacement - .

[0020] According to some preferred embodiments of the present application, the mass ratio of the potassium permanganate to the hydrogen peroxide is 2-4:1.

[0021] According to some preferred embodiments of the present application, the electrolyte solution of the liquid crystal polymer layer further includes a solubilizer, and the weight percentage of the solubilizer in the electrolyte solution of the liquid crystal polymer layer is 10%-15%.

[0022] According to some preferred embodiments of the present application, the solubilizer is ethylenediamine; the electrolyte solution of the liquid crystal polymer layer includes K2MnO4, KOH, ethylenediamine, H2O2; and the mass ratio of K2MnO4, KOH, ethylenediamine, H2O2 in the electrolyte solution of the liquid crystal polymer layer is 35-38:2-5:10-13:12-15.

[0023] The alkali metal salt solution can independently etch the polyimide film, and can etch the liquid crystal polymer film in cooperation with the solubilizer. Potassium permanganate (K2MnO4) is selected as the etchant precursor in an alkaline environment, and the etchant potassium permanganate (KMnO4) is generated on the surface of the micro working electrode by electrochemical induction, as shown in equation 2.1. Ethylenediamine is selected as the solubilizer, and the LCP film reacts with KMnO4 on the surface of the micro electrode under the action of ethylenediamine to achieve etching. In order to limit the diffusion of the etchant, hydrogen peroxide (H2O2) is selected as the restricting agent, and the restricting agent and the etchant react homogeneously on the surface of the micro working electrode to limit the diffusion of the etchant, as shown in equation 2.2.

[0024] (MnO4) 2- -e=(MnO4) - (2.1)

[0025] 2KMnO4+3H2O2=2KOH+2MnO2+3O2+2H2 (2.2)

[0026] In some embodiments, the etching-constraint system electrolyte solution of the prepared LCP layer comprises the following components at weight (mass) percentage concentrations: 35–38% K₂MnO₄, 2–5% KOH, 10–13% ethylenediamine, 12–15% H₂O₂, and the balance being water. Since LCP is a polymer resin, the precise concentration of each component in the electrolyte solution system cannot be controlled during constrained etching; the concentration ranges above represent preferred concentration ranges for each component.

[0027] According to some preferred embodiments of the present invention, the parameters for etching the copper layer using the copper layer electrolyte solution are: constant current electrolysis, with a current density of 10–15 mA / cm². 2 The system temperature is 35℃-40℃.

[0028] According to some preferred embodiments of the present invention, the parameters for etching the liquid crystal polymer layer using the liquid crystal polymer electrolyte solution are: constant current electrolysis, with a current density of 16–20 mA / cm². 2 The system temperature is 75℃-90℃.

[0029] This application also provides a method for fabricating micropores in a liquid crystal polymer substrate using the above-mentioned electrolyte solution, comprising the following steps:

[0030] Electrolyte solutions for a copper layer and a liquid crystal polymer layer are prepared separately; a working electrode is fabricated; using the working electrode, the copper layer and the liquid crystal polymer layer are sequentially etched by electro-electrode through the electrolyte solution for the copper layer and the electrolyte solution for the liquid crystal polymer layer, respectively, to obtain the micropores, wherein the micropores penetrate the copper layer and the liquid crystal polymer layer or partially penetrate the liquid crystal polymer layer; the electrolyte solution includes an etchant precursor and a constraining agent.

[0031] According to some preferred embodiments of the present invention, the working electrode is prepared by the following steps:

[0032] A metal wire (platinum wire) is placed inside a capillary glass tube. The middle section of the capillary glass tube is heated, and as the capillary glass tube melts, opposing tensions are applied to both ends, causing the middle section to break off and form a microelectrode. The tip of the microelectrode is then sealed with resin, polished, and finally the resin is dissolved to unseal the microelectrode, yielding the working electrode. The diameter of the micro-working electrode determines the extent of the etchant layer, which in turn determines the diameter of the etched micropores. Therefore, fabricating micropores of a specific size on an LCP substrate requires processing microelectrodes of corresponding diameters. In some embodiments, the diameter of the micro-working electrode tip ranges from 5µm to 10µm.

[0033] The encapsulated resin used in the preparation of the working electrode is soluble resin, such as acrylic resin, and the unsealing is carried out by soaking in a solvent, such as acetone.

[0034] According to some preferred embodiments of the present application, the etching of the copper layer is carried out according to the following steps:

[0035] The electrolyte solution covering the copper layer on the surface of the liquid crystal polymer flexible substrate is stopped from dropping when the distance between the tip of the working electrode and the surface of the liquid crystal polymer substrate is less than the depth of the electrolyte solution, and the electric etching is carried out.

[0036] According to some preferred embodiments of the present application, in the electric etching, the working electrode is moved along the circumference of the desired etching micro-hole with the initial position of the tip of the working electrode as the center according to the size of the micro-hole, and the tip of the working electrode is controlled to move downward, and the electric etching is stopped when the tip of the working electrode reaches the surface of the liquid crystal polymer layer, and the etching of the copper layer is completed. The movement of the working electrode along the circumference of the desired etching micro-hole can be continuous or intermittent, and the interval time is determined by the etching speed, and the current density and the composition of the electrolyte solution should be considered comprehensively. The moving distance of the micro working electrode is determined by the thickness of the etchant layer and the etching speed.

[0037] According to some preferred embodiments of the present application, the thickness of the electrolyte solution is calculated according to the following formula:

[0038] δ = (D etc / k s ) 1 / 2

[0039] In the formula, δ is the thickness of the electrolyte solution, D etc is the diffusion coefficient of the corresponding etchant in the electrolyte solution, and k s is the quasi-first-order reaction rate constant of the constraint reaction.

[0040] According to some preferred embodiments of the present application, the etching of the liquid crystal polymer layer is carried out according to the following steps:

[0041] When the tip of the working electrode reaches the surface of the liquid crystal polymer layer, the electrolyte solution is replaced by the electrolyte solution for the liquid crystal polymer layer, and the electric etching is carried out. In the electric etching, the working electrode is moved along the circumference of the desired etching micro-hole with the initial position of the tip of the working electrode as the center according to the size of the micro-hole, and the tip of the working electrode is controlled to move downward, and the electric etching is stopped when the tip of the working electrode reaches the set depth, and the etching of the liquid crystal polymer layer is completed. The specific process of the electric etching is similar to the etching of the copper layer described above. Since the chemical etching method is used, the etching micro-hole is roughened on the surface of the hole wall, which is beneficial to the adhesion of the subsequent electroplated copper layer.

[0042] Compared with the prior art, the electrolyte solution based on the etching restraint system has the advantages that the electrolyte solution can be used to carry out etching on the copper layer and the LCP layer of the LCP flexible substrate based on the etching restraint technology, the micro-holes with small diameter and high depth-width ratio (10-15) can be processed on the LCP flexible substrate, the problems caused by heat accumulation during the hole manufacturing process can be avoided, the hole type is ensured to be good, and the roughening of the hole wall is realized at the same time, and the efficiency is high. BRIEF DESCRIPTION OF DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort.

[0044] Figure 1 It is a schematic diagram of the micro-hole manufacturing device of the LCP flexible substrate in the preferred embodiment of the present application.

[0045] Figure 2 It is a schematic diagram of the micro-fine working electrode manufacturing process in the preferred embodiment of the present application.

[0046] Figure 3 It is a schematic diagram of the principle of copper layer etching in the preferred embodiment of the present application.

[0047] Figure 4 It is a schematic diagram of the principle of LCP layer etching in the preferred embodiment of the present application.

[0048] Figure 5 It is a schematic diagram of the electrode clamp in the preferred embodiment of the present application.

[0049] Figure 6 It is a micro-hole picture prepared by the method in the preferred embodiment of the present application.

[0050] In the drawings, container-1, liquid inlet-2, liquid outlet-3, LCP flexible substrate-4, computer-5, electrochemical workstation-6, reference electrode-7, counter electrode-8, micro-fine working electrode-9, three-dimensional motion platform-10, CCD camera-11, capillary glass tube-12, platinum wire-13, resin-14, array micro-electrode clamp-15, electrode clamping piece-16, sliding groove-17, electrolyte solution-18, micro-hole-19. DETAILED DESCRIPTION

[0051] In order to make the person skilled in the art better understand the technical solutions of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by the person skilled in the art without creative labor should belong to the protection scope of the present application.

[0052] Example 1 LCP flexible substrate micropore manufacturing equipment

[0053] The LCP flexible substrate micropore manufacturing equipment in the present embodiment is used for matching the manufacturing of liquid crystal polymer flexible substrate micropores by using etching constraint technology.

[0054] As shown in Figure 1 , the LCP flexible substrate micropore manufacturing equipment in the present embodiment includes a container 1, an electrochemical workstation 6, an electrode connected with the electrochemical workstation 6, a control module (a computer 5), a motion module (a three-dimensional motion platform 10), and a visual module (a CCD camera 11). The electrochemical workstation 6, the motion module, and the visual module are respectively connected with the control module.

[0055] The container 1 is used for containing an LCP flexible substrate 4 and an electrolyte solution 18, and a liquid inlet 2 is formed at the top of the container 1. A liquid outlet 3 is formed at the bottom of the container 1 away from the side of the liquid inlet 2, for facilitating the injection, discharge, and replacement of the electrolyte solution 18.

[0056] The electrode includes a reference electrode 7, a counter electrode 8, and a micro-working electrode 9. The motion module is used for driving the micro-working electrode (and the counter electrode 8) to move in three dimensions. The counter electrode 8 in the present embodiment is selected to be a ring electrode, and the micro-working electrode 9 is located in the ring electrode and preferably at the center position of the ring electrode, so that the electric field is more uniform.

[0057] The CCD camera 11 is used for monitoring the position of the tip (lower end) of the micro-working electrode 9 and feeding back to the computer 5 in time. The computer 5 controls the electrochemical workstation 6 and the three-dimensional motion platform 10 to make corresponding actions according to the position of the tip of the micro-working electrode 9, such as controlling the current size and the power-on time, and driving the further movement of the electrode.

[0058] Example 2 A method for manufacturing micropores suitable for liquid crystal polymer substrates

[0059] The present embodiment provides a method for manufacturing liquid crystal polymer flexible substrate micropores based on etching constraint technology and the LCP flexible substrate micropore manufacturing equipment in Example 1, which specifically includes the following steps:

[0060] I. Preparation of etching-constraint system electrolyte solution of copper layer

[0061] The etching-restraining system electrolyte solution for the copper layer in this embodiment includes the following components with the following molar concentrations: 0.04 mol / L FeCl2, 0.012 mol / L bipy, 0.2 mol / L SnCl2, and 0.2 mol / L HCl.

[0062] The electrolyte solution 18 is prepared by the chemical solution preparation method. The specific mass of the corresponding electrolyte substance is weighed according to the above-mentioned molar concentrations, and then dissolved in a specific volume of deionized water. After being mixed uniformly, the electrolyte solution 18 is obtained.

[0063] FeCl2 is selected as the etchant precursor. The etchant FeCl3 is generated on the surface of the micro work electrode 9 by electrochemical induction. The etchant reacts with copper to etch the copper layer. 2,2-bipyridine (bipy) is selected as the complexing agent to accelerate the etching speed. Stannous chloride SnCl2 is selected as the restraining agent. The restraining agent reacts with the etchant on the surface of the micro work electrode 9 to limit the diffusion of the etchant.

[0064] II. Preparation of the etching-restraining system electrolyte solution for the liquid crystal polymer (LCP) layer

[0065] The etching-restraining system electrolyte solution for the LCP layer in this embodiment includes the following components with the following weight (mass) percentage concentrations: 35-38% of K2MnO4, 2-5% of KOH, 10-13% of ethylenediamine, 12-15% of H2O2, and the rest of deionized water.

[0066] The electrolyte solution 18 is prepared by the chemical solution preparation method. The specific mass of the corresponding electrolyte substance is weighed according to the above-mentioned molar concentrations, and then dissolved in a specific volume of deionized water. After being mixed uniformly, the electrolyte solution 18 is obtained. Although potassium permanganate needs to be used as the etchant precursor in an alkaline environment, it can be mixed uniformly during the preparation of the electrolyte solution. The reaction occurs after electrification.

[0067] The alkali metal salt solution can etch the polyimide film independently, and can etch the liquid crystal polymer film with the cooperation of the solubilizing agent. Potassium permanganate (K2MnO4) is selected as the etchant precursor in an alkaline environment. The etchant potassium permanganate (KMnO4) is generated on the surface of the micro work electrode 9 by electrochemical induction. Ethylenediamine is selected as the solubilizing agent. The LCP film reacts with KMnO4 on the surface of the micro electrode under the action of ethylenediamine to achieve etching. In order to limit the diffusion of the etchant, hydrogen peroxide (H2O2) is selected as the restraining agent. The restraining agent reacts with the etchant on the surface of the micro work electrode 9 to limit the diffusion of the etchant.

[0068] III. Fabrication of the micro work electrode 9

[0069] The diameter of the micro working electrode 9 determines the range of the etchant layer, and thus the diameter of the etched micropore 19. Therefore, to make a micropore 19 of a specific size on the LCP substrate, a micro electrode of a corresponding diameter size needs to be processed.

[0070] The method for making the micro electrode is shown in Figure 2 The process for making the micro working electrode 9 in this embodiment is as follows: first, place the platinum wire 13 in the capillary glass tube 12, then heat the middle position of the capillary glass tube 12 by electric current, when the capillary glass tube 12 is melted, apply opposite pulling forces at both ends of the capillary glass tube 12 to break the middle position of the capillary glass tube 12 to form a micro electrode, then seal the tip of the micro electrode with a dissolvable resin 14 such as acrylic resin 14, then polish the tip of the micro electrode to a mirror finish, and finally soak the micro electrode in acetone to dissolve the sealing material and release the micro electrode to form a micro working electrode.

[0071] In this embodiment, a high-precision micro electrode drawing instrument P-2000 produced by Sutter Company in the United States is used to make the micro working electrode, and the tip diameter of the working electrode obtained is in the range of 5um-10um.

[0072] Four, etching the LCP flexible substrate 4 to make the micropore 19

[0073] The principle of making the micropore 19 on the LCP flexible substrate 4 based on the constrained etchant layer technology is shown in Figures 3-4 .

[0074] First, inject the etching-constrained system electrolyte solution 18 of the copper layer into the container 1, control the micro working electrode 9 to descend through the three-dimensional motion platform 10, observe the distance between the tip of the micro working electrode 9 and the LCP flexible substrate 4 through the CCD camera 11, stop descending when the distance between the tip of the micro working electrode 9 and the surface of the LCP flexible substrate 4 (d) is less than the thickness (δ) of the constrained etchant layer, and etch by electrification, as shown in Figure 3 .

[0075] The thickness (δ) of the constrained etchant layer is calculated according to formula 4.1, where D etc is the diffusion coefficient of the corresponding etchant in the electrolyte, and k s is the quasi-first-order reaction rate constant of the constrained reaction.

[0076] δ = (D etc / k s ) 1 / 2 (4.1)

[0077] After power on, the microelectrode moves along the circumference of the desired etching micropore 19 with the initial position as the center according to the size of the micropore 19, and the intermittent time is determined by the etching speed, which needs to be comprehensively considered in combination with the current density and the composition of the electrolyte solution 18. At the same time, the micro-distance of the micro working electrode 9 moves downward, and the moving distance is determined by the thickness of the etchant layer and the etching speed.

[0078] When the CCD camera 11 observes that the tip of the micro working electrode 9 reaches the surface of the LCP layer, the electrolyte solution 18 is replaced by the etching-restricted system electrolyte solution 18 of the LCP layer through the inlet / outlet 3, and power is supplied for etching. The process is generally similar to the etching of the copper layer described above, and will not be repeated here. Since the chemical etching method is adopted, the micropore 19 is etched at the same time, and the surface of the hole wall is roughened, as shown in FIG. 6, which is beneficial to enhance the adhesion of the subsequent electroplated copper layer. Figure 4

[0079] Through the above LCP flexible substrate micropore manufacturing equipment, electrolyte solution and method, a micropore with a depth-width ratio of 10-15 can be prepared, as shown in FIG. 6. Figure 6

[0080] The high-precision CCD camera 11 can shoot the movement trajectory of the working electrode tip, and the image is transmitted to the computer 5 for manual monitoring, or through the image processing algorithm to write a control program to realize automatic control.

[0081] In some embodiments, multiple micropores 19 need to be opened on the LCP flexible substrate 4. For the manufacturing of a large number of micropores 19 of the LCP flexible substrate 4, according to the layout of the micropores 19 of the LCP flexible substrate 4, an array microelectrode clamp 15 shown in FIG. 5 is adopted to manufacture the array microelectrode. For blind holes or through holes with the same depth, the array microelectrode can be manufactured at one time, and the array microelectrode clamp 15 adopts a movable design of the movable type printing die, and the array microelectrode can be flexibly adjusted for different micropore 19 layouts.

[0082] Figure 5 The array microelectrode clamp 15 shown in FIG. 5 is provided with a plurality of electrode clamping pieces 16 and a plurality of sliding grooves 17, and the electrode clamping pieces 16 can clamp the micro working electrode 9 and slide in the sliding grooves 17. In work, the position of the electrode is adjusted according to the position of the designed micropore 19 on the array microelectrode clamp 15, and then the whole electrode is moved by the three-dimensional motion platform 10 to realize batch hole making.

[0083] For the convenience of description and understanding, the above steps are numbered and described respectively, but they have no limiting meaning. In actual cases, the above steps such as the preparation of the electrolyte solution and the micro working electrode can be carried out at the same time or without a sequence.

[0084] ​​The LCP material has poor hot melt property, and the existing mechanical drilling and laser drilling methods are prone to produce glue dregs. The method for processing the micro-hole of the LCP flexible substrate based on the constrained etchant layer technology in the application belongs to a non-contact electrochemical etching cold processing method, and can avoid hot melting. Compared with the existing LCP drilling process, the method has the following advantages: compared with the mechanical drilling method, the non-contact processing method can avoid tool wear, workpiece surface mechanical damage and residual stress and other problems; compared with the mechanical drilling and laser drilling methods, the electrochemical cold processing method has no thermal effect due to low electrochemical reaction heat and the cooling effect of the electrolyte solution, and can avoid problems such as hot melting and internal shrinkage caused by heat accumulation in the hole during hole processing; compared with the single-hole processing methods such as mechanical drilling and laser drilling, the method can realize batch processing of micro-holes through a micro-electrode array, and greatly improve the production efficiency; compared with the physical drilling methods such as mechanical drilling and laser drilling, the electrochemical etching method can realize hole wall roughening while processing the micro-hole, shorten the process flow, and improve the production efficiency; compared with the high-precision mechanical drilling equipment and laser drilling equipment, the equipment for realizing the method is simple and low in cost, and the production cost is reduced.

[0085] The above examples are only for illustrating the technical concept and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and implement it, and cannot limit the protection scope of the present application. Any equivalent changes or modifications made according to the spirit and essence of the present application should be covered within the protection scope of the present application.

Claims

1. An electrolyte solution based on an etch constraint system, characterized in that, The electrolyte solution is used for etching and forming micropores on a copper layer and a liquid crystal polymer layer of a liquid crystal polymer substrate; the electrolyte solution comprises an etchant precursor and a constraint agent; the electrolyte solution comprises a copper layer electrolyte solution and a liquid crystal polymer layer electrolyte solution for etching the copper layer and the liquid crystal polymer layer respectively; The etchant precursor in the electrolyte solution of the copper layer is FeCl2, and the constraint agent is SnCl2; The etchant precursor in the electrolyte solution of the liquid crystal polymer layer is potassium permanganate, and the constraint agent is hydrogen peroxide; The molar ratio of FeCl2 to SnCl2 in the electrolyte solution is 0.1-0.5:1; The electrolyte solution of the copper layer further comprises a complexing agent, the molar concentration of the complexing agent in the electrolyte solution of the copper layer is 0.01-0.02 mol / L; the mass ratio of potassium permanganate to hydrogen peroxide is 2-4:1; the electrolyte solution of the liquid crystal polymer layer further comprises a solubilizing agent, the weight percentage of the solubilizing agent in the electrolyte solution of the liquid crystal polymer layer is 10%-15%.

2. The electrolyte solution of claim 1, wherein, The complexing agent is 2,2-bipyridine, and the electrolyte solution of the copper layer comprises HCl; the molar ratio of FeCl2, 2,2-bipyridine, SnCl2, HCl is 0.1-0.3:0.03-0.09:1:0.5-1.

5.

3. The electrolyte solution of claim 1, wherein, The solubilizing agent is ethylenediamine; the electrolyte solution of the liquid crystal polymer layer comprises K2MnO4, KOH, ethylenediamine, H2O2; the mass ratio of K2MnO4, KOH, ethylenediamine, H2O2 in the electrolyte solution of the liquid crystal polymer layer is 35-38:2-5:10-13:12-15.

4. The electrolyte solution of claim 1, wherein, The parameters for etching the copper layer using the copper layer electrolyte solution are: constant current electrolysis, current density is 10-15 mA / cm 2 , system temperature is 35-40 DEG C.

5. The electrolyte solution of claim 1, wherein The parameters for etching the liquid crystal polymer layer using the liquid crystal polymer electrolyte solution are: constant current electrolysis, current density of 16-20 mA / cm 2 , and system temperature of 75-90°C.

6. A method for making micropores on a liquid crystal polymer substrate by using the electrolyte solution according to any one of claims 1-5.

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