A method for optimizing the impedance continuity of PCB transmission lines

Abstract

This invention discloses a method and system for optimizing the impedance continuity of PCB transmission lines. The method includes: simulating an initial three-dimensional physical model of the PCB impedance abrupt change region to obtain initial equivalent capacitance and inductance density distribution data; inversely solving the three-dimensional equivalent dielectric constant requirement matrix based on the target characteristic impedance and converting it into an air volume fraction matrix; mapping this matrix to physical control parameters and compiling it to generate multi-dimensional CNC machining code; performing spatial gradient laser ablation on the PCB dielectric layer according to the code to process non-metallic micropores with spatially varying depth and distribution density to construct a micro-air gap matrix; heating and pressing the dielectric layer with the micro-air gap matrix to the PCB laminate structure to be pressed together; and utilizing the damping force generated by the thermal expansion of air inside the micro-air gap matrix to counteract the infiltration of molten resin. This invention achieves precise spatial adjustment of the dielectric constant, solves the impedance discontinuity problem, and ensures the stability of air gap formation.

Description

Technical Field

[0001] This invention relates to the field of printed circuit board manufacturing technology, specifically to a method and system for optimizing the impedance continuity of PCB transmission lines. Background Technology

[0002] In high-speed, high-frequency electronic products, the signal integrity of printed circuit boards is very important. When PCB transmission lines pass through areas such as via arrays, high-frequency connector pads, and cross-layer transition traces, the spatial transformation of the circuit structure will generate additional parasitic capacitance and parasitic inductance, which will cause local impedance abrupt changes and high-frequency signal reflection.

[0003] Existing impedance optimization methods typically rely on adjusting the trace width in a two-dimensional plane, increasing the reference layer spacing, or directly using a low dielectric constant substrate. These conventional methods can only provide passive compensation at the macroscopic level or in a two-dimensional plane. They cannot perform precise gradient adjustment of the three-dimensional dielectric constant for the complex spatial electromagnetic field in the impedance abrupt region, and it is difficult to eliminate the impedance discontinuity caused by abrupt changes in the three-dimensional physical structure.

[0004] Theoretically, local impedance compensation can be achieved by processing micro-gaps (introducing air) inside the local dielectric layer to reduce the effective dielectric constant. However, in the physical manufacturing of multilayer PCBs, a high-temperature and high-pressure lamination process is required. During the lamination stage, the insulating prepreg melts when heated and exhibits a viscous flow state. Driven by capillary hydrodynamics at the microscale, the molten resin easily penetrates into the pre-processed micropores. Once the micropores are filled with resin, the solution of introducing air to adjust the dielectric constant will fail.

[0005] Conventional lamination processes typically require vacuuming and applying high physical pressure. Under such processing conditions, air inside the tiny pores is easily extracted, resulting in a lack of physical support to resist external pressure inside the micropores. When high-pressure molten resin from the outside rushes in, the microscopic air gap structure is prone to geometric deformation or even complete collapse, making it difficult to maintain a stable air medium distribution state inside the final cured PCB stack-up structure. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a method and system for optimizing the impedance continuity of PCB transmission lines. This solves the problem of impedance discontinuity in transmission lines caused by abrupt changes in physical structure in high-frequency printed circuit boards. It also addresses the issue that in traditional local dielectric modification processes, when introducing micro-gap structures to adjust the dielectric constant, the internal space of the micro-gap is easily penetrated and filled by molten resin during the high-temperature and high-pressure lamination stage, thereby damaging the structure and causing impedance optimization failure.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a method for optimizing the impedance continuity of PCB transmission lines, characterized by comprising: Obtain the PCB design file to be optimized and the initial relative permittivity of the corresponding PCB substrate, and extract the initial three-dimensional physical model of the impedance change region in the PCB design file. Full-wave electromagnetic field simulation calculations are performed on the initial three-dimensional physical model, and the initial equivalent capacitance density distribution data, which characterizes the distributed capacitance of the impedance abrupt change region in the initial state, and the initial equivalent inductance density distribution data, which characterizes the distributed inductance of the impedance abrupt change region in the initial state, are output. Obtain the target characteristic impedance preset for the impedance change region, and calculate the target equivalent capacitance distribution matrix based on the mapping relationship between the target characteristic impedance and the distributed inductance and the distributed capacitance, while keeping the initial equivalent inductance density distribution data unchanged. Based on the target equivalent capacitance distribution matrix, the initial equivalent capacitance density distribution data, and the initial relative permittivity, calculate the three-dimensional equivalent permittivity requirement matrix; The preset equivalent dielectric theory algorithm is invoked to convert the three-dimensional equivalent dielectric constant requirement matrix into an air volume fraction matrix in a spatial coordinate system. The air volume fraction matrix is ​​mapped to the physical control parameters of the laser processing equipment, and multi-dimensional CNC machining code is compiled and generated. The multi-dimensional CNC machining code includes three-dimensional spatial coordinate parameters, laser pulse energy parameters, laser focus depth parameters, and hole array spacing parameters. According to the multi-dimensional CNC machining code, spatial gradient laser ablation is performed on the PCB dielectric layer to be processed, which is composed of the PCB substrate. Non-metallic micropores with spatially varying depth and distribution density are processed inside the PCB dielectric layer. The non-metallic micropores construct a micro-air gap matrix containing internal air inside the PCB dielectric layer to form a dielectric layer with the micro-air gap matrix. A PCB stack structure to be laminated is obtained, the PCB stack structure to be laminated includes an insulating prepreg as an interlayer bonding medium. The dielectric layer with the micro-gap matrix is ​​heated and laminated with the PCB stack structure to be laminated. During the heating and lamination, the air inside the micro-gap matrix is ​​heated and expands in volume, forming a damping force to resist the penetration of molten resin generated by the heating of the insulating prepreg into the micro-gap matrix, so as to control the externally applied lamination pressure to be less than the damping force, so that the micro-gap matrix is ​​formed inside the cured PCB stack structure.

[0008] Preferably, the step of calculating the target equivalent capacitance distribution matrix and the three-dimensional equivalent dielectric constant requirement matrix based on the mapping relationship between the target characteristic impedance and the distributed inductance and the distributed capacitance includes: Extract the distributed inductance value at each three-dimensional spatial coordinate from the initial equivalent inductance density distribution data; The target capacitance value corresponding to each of the three-dimensional spatial coordinates is calculated according to the mapping calculation formula to form the target equivalent capacitance distribution matrix containing the three-dimensional spatial coordinate attributes. The mapping calculation formula is configured such that the target capacitance value is equal to the distributed inductance value divided by the square of the target characteristic impedance. Extract the target capacitance value from the target equivalent capacitance distribution matrix, and extract the initial capacitance value corresponding to each of the three-dimensional spatial coordinates from the initial equivalent capacitance density distribution data; The relative permittivity requirement value at each of the three-dimensional spatial coordinates is calculated based on the calculation formula of the permittivity requirement, and the three-dimensional equivalent permittivity requirement matrix is ​​generated. The calculation formula of the permittivity requirement is configured such that the relative permittivity requirement value is equal to the initial relative permittivity multiplied by the ratio of the target capacitance value to the initial capacitance value.

[0009] Preferably, converting the three-dimensional equivalent dielectric constant requirement matrix into an air volume fraction matrix in a spatial coordinate system includes: Extract the relative permittivity requirement value at each three-dimensional spatial coordinate in the three-dimensional equivalent permittivity requirement matrix, and obtain the preset relative permittivity of air; The calculation formula based on the equivalent medium theory algorithm calculates the local air volume duty cycle corresponding to each of the three-dimensional spatial coordinates to generate the air volume fraction matrix. The calculation formula of the equivalent medium theory algorithm is configured such that the quotient of the difference between the required relative permittivity and the initial relative permittivity divided by the sum of the required relative permittivity and twice the initial relative permittivity is equal to the local air volume duty cycle multiplied by a preset constant ratio. The preset constant ratio is the quotient of the difference between the air relative permittivity and the initial relative permittivity divided by the sum of the air relative permittivity and twice the initial relative permittivity.

[0010] Preferably, the air volume fraction matrix is ​​mapped to the physical control parameters of the laser processing equipment, and multi-dimensional CNC machining code is compiled, including: Extract the local air volume duty cycle corresponding to each three-dimensional spatial coordinate node in the air volume fraction matrix; Based on a preset discrete processing parameter mapping model, the local air volume duty cycle is separated into single-hole geometric volume requirements and spatial array density requirements. The single-hole geometric volume requirement is mapped to the laser pulse energy parameter and the laser focus depth parameter. Specifically, the mapping logic is configured such that when the single-hole geometric volume requirement increases, the laser pulse energy parameter is simultaneously increased to expand the forming aperture of the non-metallic micro-hole to be processed, and the laser focus depth parameter is increased to deepen the forming depth of the non-metallic micro-hole. The spatial array density requirement is mapped to the perforation array spacing parameter. Specifically, the mapping logic is configured such that when the spatial array density requirement increases, the perforation array spacing parameter is reduced inversely to increase the array arrangement density of the non-metallic micropores. The three-dimensional spatial coordinate parameters, the laser pulse energy parameters, the laser focal depth parameters, and the hole array spacing parameters are time-series encapsulated to generate discrete single-step CNC machining program segments, which are then compiled to obtain the multi-dimensional CNC machining code.

[0011] Preferably, the step of performing spatial gradient laser ablation on the PCB dielectric layer to be processed, which is composed of the PCB substrate, according to the multi-dimensional CNC machining code includes: The laser processing equipment is equipped with an ultrashort pulse laser generator and a spatial optical path adjustment module; The ultrashort pulse laser generator outputs a single pulse laser beam according to the laser pulse energy parameters, and the spatial optical path adjustment module adjusts the focusing depth of the single pulse laser beam according to the laser focus depth parameters. At a preset operating wavelength, the single-pulse laser beam penetrates the PCB substrate with transmission characteristics, focuses at a specified three-dimensional coordinate depth inside the PCB substrate, and makes the energy density of the single-pulse laser beam exceed the photothermal vaporization threshold of the PCB substrate, causing the local medium inside the PCB substrate to vaporize, thereby forming the non-metallic micropores. Multiple non-metallized micropores are sequentially distributed within the impedance abrupt change region to form a discrete array set, thereby constituting the micro-air gap matrix, i.e., a three-dimensional micro-air gap envelope structure.

[0012] Preferably, after forming the three-dimensional micro-gap envelope structure and before heat-pressing the dielectric layer having the micro-gap matrix with the PCB laminate to be laminated, the method further includes: The plasma modification equipment is configured with a reaction vacuum chamber, a reaction gas supply module and a radio frequency power generator. The PCB substrate having the three-dimensional micro-gap envelope structure is positioned inside the reaction vacuum chamber, and the reaction gas supply module is controlled to introduce fluorine-based reaction gas into the reaction vacuum chamber. The radio frequency power generator is activated to output a radio frequency electromagnetic field, which ionizes the fluorine-based reactive gas and converts it into fluorine-based plasma. The fluorine-based plasma undergoes a surface grafting and substitution reaction with the resin medium of the PCB substrate whose inner wall of the non-metallized micropores is exposed, thereby generating a fluorine-containing passivation layer on the inner wall surface of the non-metallized micropores.

[0013] Preferably, the step of causing the fluorine-based plasma to undergo a surface grafting and substitution reaction with the resin medium of the PCB substrate with exposed inner walls of the non-metallized micropores to generate a fluorine-containing passivation layer on the inner wall surface of the non-metallized micropores includes: After being subjected to laser ablation, the resin medium surface exposed on the inner wall of the non-metallized micropores inherently exposes active functional groups that constitute high surface energy polar groups. The high surface energy polar groups on the surface of the resin medium are replaced by fluorine groups in the fluorine-based plasma to generate the fluorine-containing passivation layer with low surface free energy physical characteristics. The fluorinated passivation layer is used to increase the solid-liquid contact angle between the inner wall surface of the non-metallic micropores and the molten resin, so that the inner wall surface of the non-metallic micropores exhibits hydrophobic physical properties.

[0014] Preferably, the step of heat-pressing the dielectric layer having the micro-air gap matrix with the PCB laminate structure to be laminated includes: A vacuum lamination molding equipment is configured to perform the heating and pressing, the vacuum lamination molding equipment being configured with a lamination heating template, a stepped pressure loading module, and a lamination vacuum chamber; The dielectric layer having the micro-gap matrix and the PCB stack structure to be laminated are positioned between the lamination heating template inside the lamination vacuum chamber; A vacuuming action is performed on the laminated vacuum chamber. During the vacuuming action, based on the gas flow resistance effect brought about by the micron-sized pore size and the aspect ratio of the deep pores of the non-metallic micropores, the initial air is trapped in the internal space of the non-metallic micropores to form a cavity for gas retention.

[0015] Preferably, the step of heat-pressing the dielectric layer having the micro-air gap matrix with the PCB laminate structure to be laminated further includes: The lamination heating template is controlled to perform initial heating on the dielectric layer with the micro-gap matrix and the PCB laminate structure to be laminated. Under the action of the initial heating temperature, the resin component inside the insulating semi-cured sheet undergoes a phase change to generate the molten resin. The stepped pressure loading module is driven to apply physical pressure through the lamination heating template so that the molten resin contacts and initially seals the pore edges of the non-metallic micropores; Due to heat conduction, the gas trapped in the pores sealed inside the non-metallic micropores expands when heated, generating a positive gas pressure inside the non-metallic micropores. This positive gas pressure and the negative repulsion pressure drop exerted by the fluorine-containing passivation layer on the molten resin by the surface tension form a physical-mechanical superposition, which counteracts the downward permeation pressure generated by the physical pressure force. The lamination heating template is controlled to increase the heating temperature, and the stepped pressure loading module is controlled to increase the pressing force, so that the molten resin covering the edge of the non-metallic micropore diameter undergoes a cross-linking and curing reaction, and a phase change is generated to form a solid insulating resin layer, so as to permanently seal the gas trapped in the pores inside the non-metallic micropores.

[0016] An impedance continuity optimization system for PCB transmission lines includes: The three-dimensional electromagnetic simulation module is used to obtain the PCB substrate and its initial relative permittivity corresponding to the PCB design file to be optimized, extract the initial three-dimensional physical model of the impedance change region in the PCB design file, perform full-wave electromagnetic field simulation calculation, and output the initial equivalent capacitance density distribution data to characterize the distributed capacitance of the impedance change region in the initial state and the initial equivalent inductance density distribution data to characterize the distributed inductance of the impedance change region in the initial state. The reverse parameter solving server is communicatively connected to the three-dimensional electromagnetic simulation module. It is used to calculate the target equivalent capacitance distribution matrix based on the preset target characteristic impedance and to calculate the three-dimensional equivalent dielectric constant requirement matrix. The CNC code compilation terminal is connected to the reverse parameter solving server and is used to call the preset equivalent medium theory algorithm to convert the three-dimensional equivalent dielectric constant requirement matrix into an air volume fraction matrix, and map the air volume fraction matrix into physical control parameters to generate multi-dimensional CNC machining code. A laser processing equipment is communicatively connected to the CNC code compilation terminal and is used to perform spatial gradient laser ablation on the PCB dielectric layer to be processed, which is composed of the PCB substrate, according to the multi-dimensional CNC processing code, so as to process a micro-air gap matrix containing internal air inside the PCB dielectric layer. A lamination apparatus is used to heat and press a dielectric layer having the micro-gap matrix with an insulating prepreg containing an interlayer bonding medium to a PCB laminate structure to be laminated. The damping effect formed by the thermal expansion of the internal air of the micro-gap matrix inhibits the penetration of molten resin generated by the heating of the insulating prepreg, so that the micro-gap matrix is ​​formed inside the cured PCB laminate structure.

[0017] This invention provides a method for optimizing the impedance continuity of PCB transmission lines. It offers the following advantages: 1. This invention achieves precise spatial adjustment of the dielectric constant for impedance abrupt change regions. A three-dimensional equivalent dielectric constant requirement matrix is ​​calculated by an inverse parameter solving server. A preset equivalent dielectric theory algorithm is then invoked to convert this matrix into an air volume fraction matrix in a spatial coordinate system. This matrix is ​​then mapped to generate multi-dimensional CNC machining code. A laser processing device performs spatial gradient laser ablation based on this code, creating non-metallic micro-holes with spatially varying depth and density within the PCB dielectric layer. This method precisely transforms the electrical requirements of the dielectric constant into local physical spatial array density requirements and single-hole geometric volume requirements, solving the impedance discontinuity problem caused by abrupt changes in the physical structure of the transmission line.

[0018] 2. This invention suppresses resin pore filling during the lamination process from the perspective of surface chemical properties. By configuring a plasma modification device to generate fluorine-based plasma, the fluorine-based plasma undergoes surface grafting and substitution reactions with the resin medium of the PCB substrate with exposed inner walls of non-metallized micropores. A fluorine-containing passivation layer with low surface free energy physical characteristics is generated on the inner wall surface of the non-metallized micropores. The fluorine-containing passivation layer expands the solid-liquid contact angle and applies a back-repulsive pressure drop to the molten resin attempting to penetrate by means of surface tension, thus counteracting the capillary force of resin penetration.

[0019] 3. This invention utilizes physical fluid dynamics mechanisms to ensure the structural stability of the micro-gap matrix after molding. During the vacuuming process in the vacuum lamination equipment, the gas flow resistance effect brought about by the non-metallic micropores traps the initial air to form pore-retained gas. During heating and pressing, the pore-retained gas sealed inside the non-metallic micropores expands due to heat, generating a positive gas pressure inside the non-metallic micropores. The positive gas pressure and the negative repulsion pressure drop generated by the fluorine passivation layer form a physical and mechanical superposition, creating a damping force against the penetration of molten resin into the micro-gap matrix. This allows the micro-gap matrix to remain intact inside the cured PCB laminate structure. Attached Figure Description

[0020] Figure 1 This is a flowchart of the impedance continuity optimization method for PCB transmission lines according to the present invention. Figure 2 This is a cross-sectional view of the dielectric layer with a micro-air gap matrix of the present invention; Figure 3 This is a cross-sectional view of the microporous anti-leakage mechanism and the stepped differential pressure lamination state of the present invention. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Example: Please see the appendix Figure 1 - Appendix Figure 3 This invention provides a method for optimizing the impedance continuity of PCB transmission lines. The impedance continuity optimization system for executing the method includes: a three-dimensional electromagnetic simulation module, a reverse parameter solving server, a CNC code compilation terminal, a laser processing equipment, and a lamination equipment.

[0023] The 3D electromagnetic simulation module receives the externally input PCB design file to be optimized, parses the PCB design file, identifies impedance abrupt change regions in the PCB design file, obtains the corresponding PCB substrate and its initial relative permittivity, and extracts the initial 3D physical model containing the impedance abrupt change regions. The 3D electromagnetic simulation module performs full-wave electromagnetic field simulation calculations on the initial 3D physical model and outputs initial equivalent capacitance density distribution data and initial equivalent inductance density distribution data. The initial equivalent capacitance density distribution data and initial equivalent inductance density distribution data are used to characterize the distributed capacitance and distributed inductance of the impedance abrupt change regions in the initial state, respectively. The initial equivalent capacitance density distribution data and initial equivalent inductance density distribution data characterize the spatial electromagnetic field energy distribution state of the impedance abrupt change regions in the initial 3D physical model. The 3D electromagnetic simulation module sends the initial equivalent capacitance density distribution data, initial equivalent inductance density distribution data, and initial relative permittivity to the inverse parameter solving server.

[0024] The reverse parameter solving server receives the initial equivalent capacitance density distribution data, initial equivalent inductance density distribution data, and initial relative permittivity output by the 3D electromagnetic simulation module. The reverse parameter solving server obtains the preset target characteristic impedance for the impedance change region, and calculates and outputs the target equivalent capacitance distribution matrix based on the function mapping relationship between the characteristic impedance and the distributed inductance and distributed capacitance, while keeping the initial equivalent inductance density distribution data unchanged. Based on the target equivalent capacitance distribution matrix and the initial relative permittivity of the PCB substrate corresponding to the PCB design file, the reverse parameter solving server calculates and outputs the 3D equivalent permittivity requirement matrix.

[0025] The CNC code compilation terminal establishes a communication connection with the reverse parameter solving server to receive the three-dimensional equivalent dielectric constant requirement matrix output by the reverse parameter solving server. The CNC code compilation terminal calls the preset equivalent medium theory algorithm to convert the three-dimensional equivalent dielectric constant requirement matrix into an air volume fraction matrix in a spatial coordinate system. The CNC code compilation terminal maps the air volume fraction matrix into the physical control parameters of the laser processing equipment, generates and outputs multi-dimensional CNC machining code, which includes three-dimensional spatial coordinate parameters, laser pulse energy parameters, laser focus depth parameters, and drilling array spacing parameters.

[0026] The laser processing equipment receives multi-dimensional CNC processing code generated by the CNC code compilation terminal. The laser processing equipment carries the PCB dielectric layer to be processed, which is composed of PCB substrate. Based on the multi-dimensional CNC processing code, the laser equipment performs spatial gradient laser ablation on the PCB dielectric layer to process a micro-gap matrix with spatially varying depth and distribution density inside the PCB dielectric layer, so as to generate a dielectric layer with a micro-gap matrix.

[0027] The laminating equipment receives a dielectric layer with a micro-gap matrix and a preset PCB stack structure to be laminated. The laminating equipment executes a lamination program with set stepped heating parameters and differential pressure control parameters to heat and press the dielectric layer with the micro-gap matrix and the PCB stack structure to be laminated. During the lamination program, the laminating equipment controls the externally applied pressing pressure and uses the damping effect formed by the thermal expansion of the air inside the micro-gap matrix to inhibit the penetration of molten resin, so that the micro-gap matrix is ​​retained inside the cured PCB stack structure after the resin cross-links and cures.

[0028] This invention provides a method for optimizing the impedance continuity of PCB transmission lines, which is applied to the aforementioned impedance continuity optimization system. The impedance continuity optimization method includes steps S100 to S600.

[0029] In step S100, the three-dimensional electromagnetic simulation module receives the externally input PCB design file to be optimized and parses the PCB design file to identify impedance change regions in the PCB design file. The three-dimensional electromagnetic simulation module obtains the PCB substrate corresponding to the PCB design file and the initial relative permittivity of the PCB substrate, and extracts the initial three-dimensional physical model containing the impedance change region. For the specific geometric construction process of extracting the initial three-dimensional physical model, those skilled in the art can use existing electronic design automation tools combined with three-dimensional modeling software to achieve this, which is a well-known technology in the field and will not be elaborated here. The three-dimensional electromagnetic simulation module performs full-wave electromagnetic field simulation calculation on the initial three-dimensional physical model and outputs the initial equivalent capacitance density distribution data and the initial equivalent inductance density distribution data. The initial equivalent capacitance density distribution data is used to characterize the distributed capacitance of the impedance change region in the initial state, and the initial equivalent inductance density distribution data is used to characterize the distributed inductance of the impedance change region in the initial state.

[0030] In step S200, the reverse parameter solving server obtains the preset target characteristic impedance for the impedance abrupt change region, and receives the initial equivalent capacitance density distribution data and initial equivalent inductance density distribution data output by the three-dimensional electromagnetic simulation module. Based on the mapping relationship between the target characteristic impedance and the distributed inductance and distributed capacitance, the reverse parameter solving server calculates the target equivalent capacitance distribution matrix. The specific mapping calculation formula is as follows: In the formula, Indicates the target characteristic impedance. Represents the initial equivalent inductance density distribution data in three-dimensional space coordinates. The distributed inductance value at that location, Represents the target equivalent capacitance distribution matrix in three-dimensional space coordinates The target capacitance value at that location.

[0031] The inverse parameter solver server calculates and outputs a three-dimensional equivalent dielectric constant requirement matrix based on the target equivalent capacitance distribution matrix, the initial equivalent capacitance density distribution data, and the initial relative permittivity.

[0032] The formula for calculating the dielectric constant requirement is: In the formula, Represents the three-dimensional equivalent dielectric constant requirement matrix in three-dimensional space coordinates. The required relative permittivity value at that location, Represents the initial relative permittivity. Represents the initial equivalent capacitance density distribution data in three-dimensional space coordinates. The initial capacitance value at that location.

[0033] In step S300, the CNC code compilation terminal receives the three-dimensional equivalent dielectric constant requirement matrix output by the reverse parameter solving server, and calls the preset equivalent medium theory algorithm to convert the three-dimensional equivalent dielectric constant requirement matrix into an air volume fraction matrix in a spatial coordinate system. The calculation formula of the preset equivalent medium theory algorithm is as follows: In the formula, Represents the air volume fraction matrix in three-dimensional space coordinates The local air volume duty cycle at that location This represents the preset relative permittivity of air.

[0034] In step S400, the CNC code compilation terminal maps the air volume fraction matrix to the physical control parameters of the laser processing equipment and compiles and generates multi-dimensional CNC machining code. The multi-dimensional CNC machining code includes three-dimensional spatial coordinate parameters, laser pulse energy parameters, laser focus depth parameters, and drilling array spacing parameters. The specific mapping logic of the physical control parameters is as follows: when the local air volume duty cycle in the spatial coordinate system increases, the CNC code compilation terminal synchronously adjusts the drilling array spacing parameter, increases the laser pulse energy parameter, and increases the laser focus depth parameter through the multi-dimensional CNC machining code.

[0035] In step S500, the laser processing equipment receives multi-dimensional CNC machining code and carries the PCB dielectric layer to be processed, which is composed of PCB substrate. The laser processing equipment performs spatial gradient laser ablation on the PCB dielectric layer according to the multi-dimensional CNC machining code. During spatial gradient laser ablation, the laser processing equipment performs basic motion control, including spatial coordinate displacement, laser pulse emission, and beam focusing, according to the three-dimensional spatial coordinate parameters, laser pulse energy parameters, and laser focus depth parameters contained in the multi-dimensional CNC machining code. This allows multiple non-metallic micro-holes controlled by the laser focus depth parameters and the hole array spacing parameters to be processed inside the PCB dielectric layer. This results in the depth and distribution density of the non-metallic micro-holes exhibiting spatially gradual properties. The non-metallic micro-holes construct a micro-air gap matrix containing internal air inside the PCB dielectric layer, forming a dielectric layer with a micro-air gap matrix. For the basic motion control of the laser processing equipment, those skilled in the art can use existing laser processing machine tool bottom-level control instructions for configuration, which is a well-known technology in the field and will not be described in detail here.

[0036] In step S600, the laminating equipment receives a dielectric layer with a micro-gap matrix and a preset PCB stack structure to be laminated, and executes a lamination program to heat and press the dielectric layer with the micro-gap matrix and the PCB stack structure to be laminated. During the lamination program, the air inside the micro-gap matrix expands due to heat, forming a damping force to resist the penetration of the external molten resin into the micro-gap matrix. The laminating equipment applies stepped heating parameters and differential pressure control parameters to control the externally applied pressing pressure to be less than the damping force when the resin reaches the molten state. After the dielectric layer with the micro-gap matrix completes the resin cross-linking and curing stage, the micro-gap matrix is ​​formed inside the cured PCB stack structure.

[0037] As a refinement of the aforementioned step S100, the three-dimensional electromagnetic simulation module performs the following specific implementation steps to establish a data mapping relationship between the initial three-dimensional physical model and the initial equivalent capacitance density distribution data and the initial equivalent inductance density distribution data.

[0038] The 3D electromagnetic simulation module receives the PCB design file to be optimized from external input and extracts the routing layer geometry parameters, dielectric layer thickness parameters, interlayer interconnect drilling parameters, and PCB substrate properties from the PCB design file. Based on the routing layer geometry parameters and interlayer interconnect drilling parameters, the 3D electromagnetic simulation module identifies impedance change regions in the PCB design file. Among them, impedance change regions include physical areas where the circuit structure undergoes a 3D spatial transformation, such as via arrays, high-frequency connector pads, and cross-layer transition trace structures. Based on the impedance change regions, the 3D electromagnetic simulation module extracts the corresponding 3D geometric topology to construct an initial 3D physical model containing the impedance change regions.

[0039] The 3D electromagnetic simulation module sets the spatial boundaries of the initial 3D physical model, establishes the 3D computational envelope region covering the impedance abrupt change region, and calls the internally configured preset finite element partitioning algorithm or finite integral partitioning algorithm to perform spatial mesh discretization processing on the 3D computational envelope region. Among them, the finite element partitioning algorithm and the finite integral partitioning algorithm are well-known conventional mesh generation techniques in the field of computational electromagnetics. Those skilled in the art can directly call and execute them using existing full-wave electromagnetic field simulation tools, so they will not be elaborated here. The 3D electromagnetic simulation module cuts the continuous 3D computational envelope region into multiple regularly arranged 3D discrete meshes; establishes a spatial global coordinate system, and assigns independent 3D spatial coordinates to the nodes of each 3D discrete mesh, thereby forming a spatial coordinate set used to carry electromagnetic field distribution data.

[0040] The 3D electromagnetic simulation module assigns material reference parameters to each 3D discrete mesh within the 3D computational envelope region based on the PCB substrate properties. These material reference parameters include the initial relative permittivity, relative permeability, and conductivity of the PCB substrate. The module sets excitation ports at the preset signal input and output terminals of the initial 3D physical model and sets absorbing boundary conditions at the outer boundary of the 3D computational envelope region. The module injects a test signal at a preset target operating frequency into the excitation ports. This preset target operating frequency is the high-frequency signal transmission frequency preset in the PCB design file to be optimized. The test signal includes excitation voltage and current parameters. The module performs full-wave electromagnetic field simulation calculations, solving the spatial Maxwell's equations based on the preset physical model to obtain the spatial electromagnetic field energy distribution state of the 3D computational envelope region at the preset target operating frequency. The spatial Maxwell's equations are well-known fundamental physical equations in computational electromagnetics, and their specific mathematical expansion is familiar to those skilled in the art, so it will not be elaborated here. Furthermore, the spatial electromagnetic field energy distribution state includes electric field energy density data and magnetic field energy density data corresponding to each 3D spatial coordinate.

[0041] The 3D electromagnetic simulation module extracts electric and magnetic field energy density data at the coordinate nodes of each 3D discrete grid from the spatial electromagnetic field energy distribution. Based on a pre-defined spatial electrostatic field energy calculation model, combined with the excitation voltage parameters of the test signal and the volume parameters of the 3D discrete grid, the module converts the electric field energy density data into local capacitance values ​​at each 3D spatial coordinate. The spatial electrostatic field energy calculation model is a well-known physical model based on the law of conservation of energy; the derivation of its underlying energy conversion formula will not be elaborated here. The 3D electromagnetic simulation module aggregates the generated local capacitance values ​​to form initial equivalent capacitance density distribution data corresponding one-to-one with the spatial coordinate set. Based on a pre-defined spatial magnetic field energy calculation model, combined with the excitation current parameters of the test signal and the volume parameters of the 3D discrete grid, the module converts the electric field energy density data into local capacitance values ​​at each 3D spatial coordinate. The grid's volume parameter converts the magnetic field energy density data into local inductance values ​​at various three-dimensional spatial coordinates. The spatial magnetic field energy calculation model is a well-known physical model based on the law of conservation of energy; the derivation of its underlying energy conversion formula will not be elaborated here. The three-dimensional electromagnetic simulation module aggregates the generated local inductance values ​​to form initial equivalent inductance density distribution data corresponding one-to-one with the spatial coordinate set. The initial equivalent capacitance density distribution data is used to characterize the distributed capacitance of the impedance abrupt change region in the initial state. The initial equivalent inductance density distribution data is used to characterize the distributed inductance of the impedance abrupt change region in the initial state. The three-dimensional electromagnetic simulation module sends the initial equivalent capacitance density distribution data and the initial equivalent inductance density distribution data, which contain the three-dimensional spatial coordinate mapping relationship, to the inverse parameter solving server as the data input source for subsequent dielectric constant calculations.

[0042] As a refinement of the aforementioned step S200, the inverse parameter solving server performs the following specific implementation steps to establish a data mapping relationship between the initial equivalent capacitance density distribution data, the initial equivalent inductance density distribution data, and the three-dimensional equivalent dielectric constant requirement matrix. The inverse parameter solving server establishes a communication connection with the three-dimensional electromagnetic simulation module to receive the initial equivalent capacitance density distribution data, the initial equivalent inductance density distribution data, and the preset initial relative dielectric constant of the PCB substrate sent by the three-dimensional electromagnetic simulation module. The inverse parameter solving server obtains the preset target characteristic impedance for the impedance abrupt change region; wherein, the target characteristic impedance is the preset global standard transmission line impedance value in the PCB design file to be optimized. The inverse parameter solving server parses the initial equivalent inductance density distribution data and, based on the PCB substrate... The material is a non-magnetic material with a constant relative permeability despite changes in spatial structure. This establishes the constant property of distributed inductance before and after laser ablation. The initial equivalent inductance density distribution data is then set as a constant constraint in the inverse parameter mapping calculation. The inverse parameter solver server extracts the local inductance values ​​at each three-dimensional spatial coordinate from the initial equivalent inductance density distribution data and calls a preset characteristic impedance mapping function. This characteristic impedance mapping function is a mathematical model based on transmission line theory, used to characterize the physical mapping relationship between characteristic impedance and inductance and capacitance. Under constant constraints, the inverse parameter solver server calculates the target capacitance value at each three-dimensional spatial coordinate based on the target characteristic impedance and the extracted local inductance values. The specific mapping calculation formula is as follows: In the formula, Indicates the target characteristic impedance. Indicates the local inductance value. The target capacitance value is represented by the inverse parameter solving server, which aggregates the calculated target capacitance values ​​to form a target equivalent capacitance distribution matrix containing three-dimensional spatial coordinate attributes. The inverse parameter solving server extracts the target capacitance value from the target equivalent capacitance distribution matrix and the local capacitance values ​​from the initial equivalent capacitance density distribution data, and calls a preset dielectric constant scaling algorithm. This algorithm is a conventional numerical conversion rule based on the physical principle that dielectric capacitance and relative dielectric constant are linearly proportional. The inverse parameter solving server calculates the required relative dielectric constant value at each three-dimensional spatial coordinate based on the ratio between the target capacitance value and the local capacitance value, combined with the initial relative dielectric constant. The formula for calculating the required dielectric constant is: In the formula, This represents the required value of the relative permittivity. Represents the initial relative permittivity. Representing the local capacitance value, the inverse parameter solver server performs matrix encapsulation on the calculated relative permittivity requirement value, and maps the relative permittivity requirement value to the corresponding three-dimensional spatial coordinate node according to the pre-built global spatial coordinate system, generating a three-dimensional equivalent permittivity requirement matrix. The three-dimensional equivalent permittivity requirement matrix is ​​used to characterize the spatial distribution set of the relative permittivity requirement values ​​corresponding to each coordinate node in the impedance change region in three-dimensional space under the premise of satisfying the target characteristic impedance. The inverse parameter solver server sends the three-dimensional equivalent permittivity requirement matrix to the CNC code compilation terminal as the compilation basis for subsequent generation of physical control parameters.

[0043] As a refinement of the aforementioned step S300, the CNC code compilation terminal executes the following specific implementation steps to establish a data mapping relationship between the three-dimensional equivalent dielectric constant requirement matrix and the air volume fraction matrix. The CNC code compilation terminal establishes a communication connection with the inverse parameter solving server to receive the three-dimensional equivalent dielectric constant requirement matrix sent by the inverse parameter solving server, and parses the three-dimensional equivalent dielectric constant requirement matrix to extract the relative dielectric constant requirement values ​​at each three-dimensional spatial coordinate. The CNC code compilation terminal obtains the preset air relative dielectric constant and the initial relative dielectric constant of the PCB substrate. The preset air relative dielectric constant is a known physical constant. Based on the physical process of introducing air into the PCB substrate during subsequent laser ablation processing, the CNC code compilation terminal will determine the relationship between the PCB substrate and the air volume fraction matrix. The dielectric layer composed of the introduced air mixture is set as a two-phase composite dielectric model. In this model, the PCB substrate is a continuous host phase, and air is a dispersed guest phase. The guest phase is equivalently configured as a subwavelength spherical micro-air gap. The CNC code compilation terminal calls a preset equivalent dielectric theory algorithm. This algorithm is a numerical model based on Maxwell-Garnett theory, used to characterize the nonlinear physical relationship between the macroscopic equivalent dielectric constant and the volume fraction of each phase in a multiphase mixture. The CNC code compilation terminal uses this algorithm, combined with the extracted relative dielectric constant requirement, the initial relative dielectric constant, and the preset air relative dielectric constant, to calculate the local air volume duty cycle at each three-dimensional spatial coordinate. The specific calculation formula of the equivalent dielectric theory algorithm is as follows: In the formula, Indicates the local air volume duty cycle. This represents the required value of the relative permittivity. Represents the initial relative permittivity. The CNC code compiler terminal calculates and generates the local air volume duty cycle based on the preset relative permittivity of air. Then, it maps the local air volume duty cycle to the corresponding three-dimensional spatial coordinate nodes according to the global spatial coordinate system, generating an air volume fraction matrix. The air volume fraction matrix is ​​used to characterize the spatial distribution set of local air volume duty cycles that need to be processed at each coordinate node in the three-dimensional space under the condition of satisfying the target characteristic impedance. The CNC code compiler terminal uses the air volume fraction matrix as the output reference data for subsequent mapping to generate the corresponding physical control parameters.

[0044] As a refinement of the aforementioned step S400, the following specific implementation steps are executed by the CNC code compilation terminal to establish a data mapping relationship between the air volume fraction matrix and the multi-dimensional CNC machining code.

[0045] The CNC code compilation terminal reads the generated air volume fraction matrix and extracts the local air volume duty cycle corresponding to each three-dimensional spatial coordinate node. The CNC code compilation terminal also extracts the pre-stored basic physical property parameters corresponding to the laser processing equipment. Among them, the basic physical property parameters include the laser spot reference diameter and the processing limit resolution.

[0046] The CNC code compilation terminal is pre-configured with a discrete machining parameter mapping model, which it calls. This model is a numerical conversion model based on the duty cycle principle of the micro-hole array geometry, used to characterize the conversion relationship between the local air volume duty cycle and discrete machining control quantities. The discrete machining control quantities include laser pulse energy parameters, laser focus depth parameters, and hole array spacing parameters. The CNC code compilation terminal uses a preset coordinate transformation matrix between the global coordinate system and the machine tool physical coordinate system of the laser processing equipment to convert each three-dimensional spatial coordinate node into three-dimensional spatial coordinate parameters containing X-axis, Y-axis, and Z-axis displacement commands. The machine tool physical coordinate system is a three-dimensional reference system that characterizes the motion reference of the laser processing equipment's physical actuator. The preset coordinate transformation matrix is ​​a pre-configured mathematical transformation matrix used to map virtual spatial coordinates to physical machining coordinates.

[0047] In the discrete machining parameter mapping model, the CNC code compiler terminal analyzes and extracts the local air volume duty cycle, and separates the corresponding single-hole geometric volume requirement and spatial array density requirement according to the preset allocation weight. The preset allocation weight is a proportional constant pre-configured based on the preset structural mechanical threshold and basic physical property parameters of the PCB substrate. It is used to uniquely limit the numerical allocation ratio of the single-hole geometric volume requirement and the spatial array density requirement in the solution process. The CNC code compiler terminal combines the basic physical property parameters and the preset laser ablation calibration database to map the single-hole geometric volume requirement into laser pulse energy parameters and laser focus depth parameters. The preset laser ablation calibration database is a set of empirical mapping data that has been pre-tested and stored to record the actual ablation aperture and ablation depth corresponding to lasers with different pulse energies and focus depths applied to the PCB substrate. The specific mapping logic is as follows: when the single-hole geometric volume requirement increases, the CNC code compiler terminal simultaneously increases the laser pulse energy parameter to expand the forming aperture of the non-metallized micro-hole to be processed, and increases the laser focus depth parameter to deepen the forming depth of the non-metallized micro-hole.

[0048] The CNC code compilation terminal maps the spatial array density requirement to the hole array spacing parameter. The specific mapping logic is as follows: when the spatial array density requirement increases, the CNC code compilation terminal reduces the hole array spacing parameter inversely within the local physical range corresponding to the three-dimensional spatial coordinate parameter, so as to improve the array arrangement density of the non-metallic micro-holes to be processed in the unit medium volume.

[0049] The CNC code compilation terminal encodes the calculated and established three-dimensional spatial coordinate parameters, laser pulse energy parameters, laser focal depth parameters, and drilling array spacing parameters into instructions according to a preset timing logic to generate multi-dimensional CNC machining code. The multi-dimensional CNC machining code is used to directly drive the laser processing equipment to perform laser ablation processing. The CNC code compilation terminal sends the multi-dimensional CNC machining code to the laser processing equipment as the driving data source for performing spatial gradient processing.

[0050] As a refinement of the aforementioned process of compiling and generating multidimensional CNC machining code, the following specific implementation steps are performed by the CNC code compilation terminal to construct multidimensional CNC machining code containing dynamic multidimensional linkage logic.

[0051] The CNC code compilation terminal reads the calculated and established three-dimensional spatial coordinate parameters, laser pulse energy parameters, laser focus depth parameters, and drilling array spacing parameters. The CNC code compilation terminal extracts the internally pre-configured CNC machine tool instruction syntax library. The CNC machine tool instruction syntax library is a pre-stored set of standardized control instructions adapted to the underlying CNC system of the laser processing equipment. It contains basic code templates for driving the laser processing equipment to perform displacement control and laser ablation actions.

[0052] The CNC code compilation terminal performs instruction mapping on the various parameters read based on the CNC machine tool instruction syntax library. Specifically, the CNC code compilation terminal maps the three-dimensional spatial coordinate parameters to the X-axis spatial positioning instructions, Y-axis spatial positioning instructions, and Z-axis spatial positioning instructions in the CNC machine tool instruction syntax library; maps the laser pulse energy parameters to the E-axis energy control instructions in the CNC machine tool instruction syntax library; maps the laser focal depth parameters to the D-axis focal length adjustment instructions in the CNC machine tool instruction syntax library; and maps the hole array spacing parameters to the S-axis step spacing instructions in the CNC machine tool instruction syntax library.

[0053] The CNC code compilation terminal performs timing encapsulation on the mapped X-axis spatial positioning instructions, Y-axis spatial positioning instructions, Z-axis spatial positioning instructions, E-axis energy control instructions, D-axis focal length adjustment instructions, and S-axis stepping distance instructions to generate discrete single-step CNC machining program segments. In each single-step CNC machining program segment, the CNC code compilation terminal establishes the physical coordinate positioning reference with the X-axis spatial positioning instructions, Y-axis spatial positioning instructions, and Z-axis spatial positioning instructions, and configures the E-axis energy control instructions, D-axis focal length adjustment instructions, and S-axis stepping distance instructions to perform synchronous parameter loading based on the physical coordinate positioning reference.

[0054] The CNC code compilation terminal is pre-configured with a machining trajectory path planning algorithm and calls the algorithm. Based on the spatial position nodes corresponding to the X-axis, Y-axis and Z-axis spatial positioning instructions contained in each single-step CNC machining program segment, the CNC code compilation terminal performs spatial sorting on the generated single-step CNC machining program segments. The machining trajectory path planning algorithm is a numerical sorting model based on the principle of the shortest path in three-dimensional space, which is used to uniquely determine the execution order of multiple single-step CNC machining program segments to form a continuous machining action flow.

[0055] The CNC code compilation terminal performs code formatting compilation on multiple single-step CNC machining program segments that form the machining action flow, based on the underlying communication parsing protocol preset in the laser processing equipment. The underlying communication parsing protocol is a communication specification pre-configured in the CNC code compilation terminal, used to define the instruction syntax format and interface mapping relationship of the multi-dimensional CNC machining code, to ensure that the compiled direct-drive executable file is compatible with the hardware controller of the laser processing equipment. The CNC code compilation terminal generates multi-dimensional CNC machining code through code formatting compilation. The multi-dimensional CNC machining code, as a direct-drive executable file containing linkage control instructions for the X-axis, Y-axis, Z-axis, E-axis, D-axis, and S-axis, is used to control the laser processing equipment. Based on the multi-dimensional CNC machining code, the laser processing equipment performs non-metallic micro-hole ablation with spatial gradient distribution characteristics inside the physical medium corresponding to the impedance abruption region.

[0056] As a refinement of the aforementioned laser processing equipment's execution process of performing non-metallic micro-hole ablation with spatial gradient distribution characteristics within the physical medium corresponding to the impedance abrupt change region based on multi-dimensional numerical control processing code, the laser processing equipment performs the following specific implementation steps to complete three-dimensional spatial gradient micro-ablation within the impedance abrupt change region of the PCB substrate.

[0057] The laser processing equipment is pre-configured with an ultrashort pulse laser generator, a spatial optical path adjustment module, and a multi-axis displacement stage. The laser processing equipment receives and parses multi-dimensional CNC machining code to extract the X-axis spatial positioning command, Y-axis spatial positioning command, Z-axis spatial positioning command, E-axis energy control command, D-axis focal length adjustment command, and S-axis stepping distance command contained therein.

[0058] The laser processing equipment fixes the PCB substrate on a multi-axis displacement worktable and establishes the processing reference zero point with the physical coordinate origin of the impedance change region.

[0059] Based on the extracted X-axis, Y-axis and Z-axis spatial positioning commands, the laser processing equipment controls the multi-axis displacement stage to perform three-dimensional spatial translation so that the target processing node on the PCB substrate is aligned with the focal output axis of the spatial optical path adjustment module.

[0060] The laser processing equipment generates an energy control electrical signal based on the E-axis energy control command and sends it to the ultrashort pulse laser generator. It also generates a focal length adjustment electrical signal based on the D-axis focal length adjustment command and sends it to the spatial optical path adjustment module. The ultrashort pulse laser generator outputs a single-pulse laser beam with corresponding pulse energy based on the energy control electrical signal. The spatial optical path adjustment module receives the single-pulse laser beam and adjusts its focusing depth according to the focal length adjustment electrical signal.

[0061] The spatial optical path adjustment module focuses the single-pulse laser beam, after adjusting the focusing depth, onto a specified three-dimensional coordinate depth inside the PCB substrate. Under the preset working wavelength of the single-pulse laser beam, the PCB substrate has transmission characteristics, and based on the nonlinear absorption effect at the focal point, the energy density of the single-pulse laser beam exceeds the photothermal vaporization threshold of the PCB substrate only in the focal region at the specified three-dimensional coordinate depth, causing the local medium inside the PCB substrate to vaporize, thereby forming non-metallic micropores.

[0062] The laser processing equipment controls the multi-axis displacement stage to perform corresponding three-dimensional spatial stepping displacement according to the S-axis stepping spacing command, and cyclically triggers the ultra-short pulse laser generator so that multiple non-metallic micro-holes are sequentially distributed in the impedance abrupt change region to form a discrete array set.

[0063] By executing all the single-step CNC machining program segments contained in the multi-dimensional CNC machining code, the laser processing equipment processes a set of non-metallic micropores in the impedance abrupt change region, in which the geometric aperture, forming hole depth and array arrangement density are continuously varied in three-dimensional space; the set of non-metallic micropores constitutes a micro-air gap matrix with spatial gradient distribution characteristics, that is, a three-dimensional micro-air gap envelope structure.

[0064] After completing the aforementioned non-metallic micropore assembly to form a three-dimensional micro-air gap envelope structure with spatial gradient distribution characteristics, as a refinement of the subsequent anti-leakage treatment process, a plasma modification device is pre-configured, and the plasma modification device performs the following specific implementation steps to perform liquefaction modification on the inner wall surface of the non-metallic micropores to inhibit resin capillary permeation. The liquefaction modification to inhibit resin capillary permeation is a surface chemical treatment process that reduces the physical surface energy of the inner wall surface of the micropores to block the liquid resin from invading the non-metallic micropores through capillary hydrodynamics in the subsequent lamination process.

[0065] The plasma modification equipment is pre-configured with a reaction vacuum chamber, a reaction gas supply module, and an RF power generator. The plasma modification equipment transports and positions the PCB substrate with non-metallized micropores inside the reaction vacuum chamber, and then performs a vacuuming operation on the reaction vacuum chamber to achieve the preset basic vacuum level.

[0066] The plasma modification equipment controls the reaction gas supply module to introduce fluorine-based reactive gas into the reaction vacuum chamber at a preset flow rate. The fluorine-based reactive gas is a pre-prepared reaction precursor medium containing carbon tetrafluoride or sulfur hexafluoride compounds, which is used to dissociate under radio frequency field excitation to generate active fluorine free radicals that participate in surface chemical reactions. The fluorine-based reactive gas penetrates into the non-metallic micropores in the PCB substrate through molecular diffusion. Molecular diffusion is a physical transport behavior driven by the gas concentration gradient difference between the main space of the reaction vacuum chamber and the microspace inside the non-metallic micropores, so that the fluorine-based reactive gas can fully cover the inner wall surface of the non-metallic micropores.

[0067] The plasma modification equipment starts the radio frequency power generator to output a radio frequency electromagnetic field to the inside of the reaction vacuum chamber. The fluorine-based reactive gas undergoes an ionization reaction under the excitation of the radio frequency electromagnetic field, and is converted into fluorine-based plasma.

[0068] Fluorine-based plasma undergoes surface grafting and substitution reactions with the resin medium of the PCB substrate with exposed inner walls of non-metallized micropores. After undergoing the physical bond breaking effect of laser ablation, the exposed inner wall surface of the resin medium inherently exposes active functional groups containing hydroxyl or carboxyl groups. These active functional groups constitute high surface energy polar groups. The fluorine groups in the fluorine-based plasma replace the high surface energy polar groups on the surface of the resin medium, generating a fluorine-containing passivation layer with low surface free energy physical characteristics on the inner wall surface of the non-metallized micropores.

[0069] After the fluorine-containing passivation layer is prepared, an insulating prepreg is applied to the surface of the PCB substrate as an interlayer bonding medium. This allows the PCB substrate and the insulating prepreg to overlap and enter the solid bonding manufacturing step under high temperature and high pressure. The solid bonding manufacturing step constitutes the printed circuit board lamination process. Under the high temperature and high pressure physical action of the printed circuit board lamination process, the resin component inside the insulating prepreg melts and generates a liquid flowing resin in a viscous state. The fluorine-containing passivation layer is used to expand the solid-liquid contact angle between the inner wall surface of the non-metallic micropores and the liquid flowing resin, so that the inner wall surface of the non-metallic micropores exhibits hydrophobic physical properties.

[0070] In the printed circuit board lamination process, when the liquid flowing resin is pressed and comes into contact with the edge of the non-metallized micropore, driven by the hydrophobic physical properties, the gas-liquid interface at the front end of the liquid flowing resin is forced to bend and deform, and a surface tension is generated from the inside of the hole to the outside of the hole. This process of interfacial tension evolution in the micro-confined space triggers the capillary hydrodynamic mechanism. Under the action of the capillary hydrodynamic mechanism, the fluorinated passivation layer applies reverse fluid resistance to the liquid flowing resin that is trying to flow in by means of surface tension. The fluid resistance is then converted into a back repulsive pressure drop against the liquid flowing resin.

[0071] The back repulsion pressure drop is used to counteract the capillary force of the liquid flowing resin penetrating inward, blocking the penetration path of the liquid flowing resin into the non-metallic micropores. The fluorinated passivation layer thus maintains the spatial geometry of the three-dimensional micro-air gap envelope structure formed by the non-metallic micropores and the distribution state of the air medium constant.

[0072] After the preceding steps maintain the spatial geometry and air medium distribution of the three-dimensional micro-air gap envelope structure composed of the non-metallic micropores by using a fluorine-containing passivation layer, a vacuum lamination equipment is pre-configured as a lamination device to refine the aforementioned printed circuit board lamination process. The vacuum lamination equipment then performs the following specific implementation steps to complete the solid lamination of the printed circuit board by utilizing the air retention effect.

[0073] The vacuum lamination molding equipment is pre-configured with a lamination heating template, a stepped pressure loading module, and a lamination vacuum chamber. The vacuum lamination molding equipment conveys the PCB substrate with non-metallized micropores and fluorine passivation layer and the aforementioned insulating semi-cured sheet in a preset stacking structure order and places them between the lamination heating templates inside the lamination vacuum chamber.

[0074] The vacuum lamination molding equipment performs a vacuum pumping action on the lamination vacuum chamber to extract the free air inside the lamination vacuum chamber. During this vacuum pumping action, due to the gas flow resistance effect caused by the micron-sized pore size and the aspect ratio of the deep pores of the non-metallic micropores, the internal space of the non-metallic micropores cannot reach the preset basic vacuum level synchronously with the main chamber, thus trapping the initial air, which constitutes the pore stagnant gas.

[0075] Then, the vacuum lamination molding equipment controls the lamination heating template to perform initial heating on the PCB substrate and the insulating prepreg according to the internally preset first-step temperature control command. Under the action of the initial heating temperature set by the first-step temperature control command, the insulating prepreg undergoes a phase change to generate liquid flowing resin.

[0076] According to the preset first-step pressure control command, the vacuum lamination molding equipment drives the stepped pressure loading module to apply physical pressure to the PCB substrate and the insulating prepreg through the lamination heating template. The physical pressure drives the liquid resin to extend and flow in a planar manner on the surface of the PCB substrate, and makes the liquid resin contact the pore edge of the non-metallized micropores.

[0077] When the liquid flowing resin contacts and initially seals the pore edge of the non-metallic micropores, the gas trapped inside the pores expands due to the continuous conduction of the initial heating temperature, generating a positive gas pressure inside the non-metallic micropores. This positive gas pressure, together with the negative repulsion pressure drop generated by the aforementioned fluorine passivation layer, forms a physical-mechanical superposition, jointly offsetting the downward permeation pressure generated by the physical pressure force transmitted to the liquid flowing resin.

[0078] Then, the vacuum lamination molding equipment controls the lamination heating template to increase the heating temperature according to the internally preset second-stage temperature control command and second-stage pressure control command, and controls the step pressure loading module to increase the pressing force. Under the action of the second-stage temperature control command and second-stage pressure control command, the liquid flowing resin covering the edge of the non-metallic micropore diameter undergoes a cross-linking and curing reaction, and a phase change is generated to form a solid insulating resin layer.

[0079] The solid insulating resin layer physically seals the edges of the non-metallic micropores, permanently sealing the trapped gas inside the non-metallic micropores. The PCB substrate and the insulating prepreg are physically bonded through the solid insulating resin layer to form a finished printed circuit board containing the aforementioned three-dimensional micro-air gap envelope structure.

[0080] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for optimizing the impedance continuity of a PCB transmission line, characterized in that, include: Obtain the PCB design file to be optimized and the initial relative permittivity of the corresponding PCB substrate, and extract the initial three-dimensional physical model of the impedance change region in the PCB design file. Full-wave electromagnetic field simulation calculations are performed on the initial three-dimensional physical model, and the initial equivalent capacitance density distribution data, which characterizes the distributed capacitance of the impedance abrupt change region in the initial state, and the initial equivalent inductance density distribution data, which characterizes the distributed inductance of the impedance abrupt change region in the initial state, are output. Obtain the target characteristic impedance preset for the impedance change region, and calculate the target equivalent capacitance distribution matrix based on the mapping relationship between the target characteristic impedance and the distributed inductance and the distributed capacitance, while keeping the initial equivalent inductance density distribution data unchanged. Based on the target equivalent capacitance distribution matrix, the initial equivalent capacitance density distribution data, and the initial relative permittivity, calculate the three-dimensional equivalent permittivity requirement matrix; The preset equivalent dielectric theory algorithm is invoked to convert the three-dimensional equivalent dielectric constant requirement matrix into an air volume fraction matrix in a spatial coordinate system. The air volume fraction matrix is ​​mapped to the physical control parameters of the laser processing equipment, and multi-dimensional CNC machining code is compiled and generated. The multi-dimensional CNC machining code includes three-dimensional spatial coordinate parameters, laser pulse energy parameters, laser focus depth parameters, and hole array spacing parameters. According to the multi-dimensional CNC machining code, spatial gradient laser ablation is performed on the PCB dielectric layer to be processed, which is composed of the PCB substrate. Non-metallic micropores with spatially varying depth and distribution density are processed inside the PCB dielectric layer. The non-metallic micropores construct a micro-air gap matrix containing internal air inside the PCB dielectric layer to form a dielectric layer with the micro-air gap matrix. A PCB stack structure to be laminated is obtained, the PCB stack structure to be laminated includes an insulating prepreg as an interlayer bonding medium. The dielectric layer with the micro-gap matrix is ​​heated and laminated with the PCB stack structure to be laminated. During the heating and lamination, the air inside the micro-gap matrix is ​​heated and expands in volume, forming a damping force to resist the penetration of molten resin generated by the heating of the insulating prepreg into the micro-gap matrix, so as to control the externally applied lamination pressure to be less than the damping force, so that the micro-gap matrix is ​​formed inside the cured PCB stack structure.

2. The impedance continuity optimization method for PCB transmission lines according to claim 1, characterized in that, The calculation of the target equivalent capacitance distribution matrix and the three-dimensional equivalent dielectric constant requirement matrix based on the mapping relationship between the target characteristic impedance, the distributed inductance, and the distributed capacitance includes: Extract the distributed inductance value at each three-dimensional spatial coordinate from the initial equivalent inductance density distribution data; The target capacitance value corresponding to each of the three-dimensional spatial coordinates is calculated according to the mapping calculation formula to form the target equivalent capacitance distribution matrix containing the three-dimensional spatial coordinate attributes. The mapping calculation formula is configured such that the target capacitance value is equal to the distributed inductance value divided by the square of the target characteristic impedance. Extract the target capacitance value from the target equivalent capacitance distribution matrix, and extract the initial capacitance value corresponding to each of the three-dimensional spatial coordinates from the initial equivalent capacitance density distribution data; The relative permittivity requirement value at each of the three-dimensional spatial coordinates is calculated based on the calculation formula of the permittivity requirement, and the three-dimensional equivalent permittivity requirement matrix is ​​generated. The calculation formula of the permittivity requirement is configured such that the relative permittivity requirement value is equal to the initial relative permittivity multiplied by the ratio of the target capacitance value to the initial capacitance value.

3. The impedance continuity optimization method for PCB transmission lines according to claim 1, characterized in that, Converting the three-dimensional equivalent dielectric constant requirement matrix into an air volume fraction matrix in a spatial coordinate system includes: Extract the relative permittivity requirement value at each three-dimensional spatial coordinate in the three-dimensional equivalent permittivity requirement matrix, and obtain the preset relative permittivity of air; The calculation formula based on the equivalent medium theory algorithm calculates the local air volume duty cycle corresponding to each of the three-dimensional spatial coordinates to generate the air volume fraction matrix. The calculation formula of the equivalent medium theory algorithm is configured such that the quotient of the difference between the required relative permittivity and the initial relative permittivity divided by the sum of the required relative permittivity and twice the initial relative permittivity is equal to the local air volume duty cycle multiplied by a preset constant ratio. The preset constant ratio is the quotient of the difference between the air relative permittivity and the initial relative permittivity divided by the sum of the air relative permittivity and twice the initial relative permittivity.

4. The impedance continuity optimization method for PCB transmission lines according to claim 1, characterized in that, The air volume fraction matrix is ​​mapped to the physical control parameters of the laser processing equipment, and multi-dimensional CNC machining code is compiled and generated, including: Extract the local air volume duty cycle corresponding to each three-dimensional spatial coordinate node in the air volume fraction matrix; Based on a preset discrete processing parameter mapping model, the local air volume duty cycle is separated into single-hole geometric volume requirements and spatial array density requirements. The single-hole geometric volume requirement is mapped to the laser pulse energy parameter and the laser focus depth parameter. Specifically, the mapping logic is configured such that when the single-hole geometric volume requirement increases, the laser pulse energy parameter is simultaneously increased to expand the forming aperture of the non-metallic micro-hole to be processed, and the laser focus depth parameter is increased to deepen the forming depth of the non-metallic micro-hole. The spatial array density requirement is mapped to the perforation array spacing parameter. Specifically, the mapping logic is configured such that when the spatial array density requirement increases, the perforation array spacing parameter is reduced inversely to increase the array arrangement density of the non-metallic micropores. The three-dimensional spatial coordinate parameters, the laser pulse energy parameters, the laser focal depth parameters, and the hole array spacing parameters are time-series encapsulated to generate discrete single-step CNC machining program segments, which are then compiled to obtain the multi-dimensional CNC machining code.

5. The impedance continuity optimization method for PCB transmission lines according to claim 1, characterized in that, The step of performing spatial gradient laser ablation on the PCB dielectric layer to be processed, which is composed of the PCB substrate, according to the multi-dimensional CNC machining code includes: The laser processing equipment is equipped with an ultrashort pulse laser generator and a spatial optical path adjustment module; The ultrashort pulse laser generator outputs a single pulse laser beam according to the laser pulse energy parameters, and the spatial optical path adjustment module adjusts the focusing depth of the single pulse laser beam according to the laser focus depth parameters. At a preset operating wavelength, the single-pulse laser beam penetrates the PCB substrate with transmission characteristics, focuses at a specified three-dimensional coordinate depth inside the PCB substrate, and makes the energy density of the single-pulse laser beam exceed the photothermal vaporization threshold of the PCB substrate, causing the local medium inside the PCB substrate to vaporize, thereby forming the non-metallic micropores. Multiple non-metallized micropores are sequentially distributed within the impedance abrupt change region to form a discrete array set, thereby constituting the micro-air gap matrix, i.e., a three-dimensional micro-air gap envelope structure.

6. The impedance continuity optimization method for PCB transmission lines according to claim 5, characterized in that, After forming the three-dimensional micro-gap envelope structure, and before heat-pressing the dielectric layer having the micro-gap matrix with the PCB laminate to be laminated, the method further includes: The plasma modification equipment is configured with a reaction vacuum chamber, a reaction gas supply module and a radio frequency power generator. The PCB substrate having the three-dimensional micro-gap envelope structure is positioned inside the reaction vacuum chamber, and the reaction gas supply module is controlled to introduce fluorine-based reaction gas into the reaction vacuum chamber. The radio frequency power generator is activated to output a radio frequency electromagnetic field, which ionizes the fluorine-based reactive gas and converts it into fluorine-based plasma. The fluorine-based plasma undergoes a surface grafting and substitution reaction with the resin medium of the PCB substrate whose inner wall of the non-metallized micropores is exposed, thereby generating a fluorine-containing passivation layer on the inner wall surface of the non-metallized micropores.

7. The impedance continuity optimization method for PCB transmission lines according to claim 6, characterized in that, The process of subjecting the fluorine-based plasma to a surface grafting and substitution reaction with the resin medium of the PCB substrate with exposed inner walls of the non-metallized micropores to generate a fluorine-containing passivation layer on the inner wall surface of the non-metallized micropores includes: After being subjected to laser ablation, the resin medium surface exposed on the inner wall of the non-metallized micropores inherently exposes active functional groups that constitute high surface energy polar groups. The high surface energy polar groups on the surface of the resin medium are replaced by fluorine groups in the fluorine-based plasma to generate the fluorine-containing passivation layer with low surface free energy physical characteristics. The fluorinated passivation layer is used to increase the solid-liquid contact angle between the inner wall surface of the non-metallic micropores and the molten resin, so that the inner wall surface of the non-metallic micropores exhibits hydrophobic physical properties.

8. The impedance continuity optimization method for PCB transmission lines according to claim 7, characterized in that, The step of heating and pressing the dielectric layer having the micro-air gap matrix with the PCB laminate structure to be laminated includes: A vacuum lamination molding equipment is configured to perform the heating and pressing, the vacuum lamination molding equipment being configured with a lamination heating template, a stepped pressure loading module, and a lamination vacuum chamber; The dielectric layer having the micro-gap matrix and the PCB stack structure to be laminated are positioned between the lamination heating template inside the lamination vacuum chamber; A vacuuming action is performed on the laminated vacuum chamber. During the vacuuming action, based on the gas flow resistance effect brought about by the micron-sized pore size and the aspect ratio of the deep pores of the non-metallic micropores, the initial air is trapped in the internal space of the non-metallic micropores to form a cavity for gas retention.

9. The impedance continuity optimization method for PCB transmission lines according to claim 8, characterized in that, The step of heating and pressing the dielectric layer having the micro-air gap matrix with the PCB laminate structure to be laminated further includes: The lamination heating template is controlled to perform initial heating on the dielectric layer with the micro-gap matrix and the PCB laminate structure to be laminated. Under the action of the initial heating temperature, the resin component inside the insulating semi-cured sheet undergoes a phase change to generate the molten resin. The stepped pressure loading module is driven to apply physical pressure through the lamination heating template so that the molten resin contacts and initially seals the pore edges of the non-metallic micropores; Due to heat conduction, the gas trapped in the pores sealed inside the non-metallic micropores expands when heated, generating a positive gas pressure inside the non-metallic micropores. This positive gas pressure and the negative repulsion pressure drop exerted by the fluorine-containing passivation layer on the molten resin by the surface tension form a physical-mechanical superposition, which counteracts the downward permeation pressure generated by the physical pressure force. The lamination heating template is controlled to increase the heating temperature, and the stepped pressure loading module is controlled to increase the pressing force, so that the molten resin covering the edge of the non-metallic micropore diameter undergoes a cross-linking and curing reaction, and a phase change is generated to form a solid insulating resin layer, so as to permanently seal the gas trapped in the pores inside the non-metallic micropores.

10. A PCB transmission line impedance continuity optimization system, used to execute the PCB transmission line impedance continuity optimization method as described in any one of claims 1 to 9, characterized in that, include: The three-dimensional electromagnetic simulation module is used to obtain the PCB substrate and its initial relative permittivity corresponding to the PCB design file to be optimized, extract the initial three-dimensional physical model of the impedance change region in the PCB design file, perform full-wave electromagnetic field simulation calculation, and output the initial equivalent capacitance density distribution data to characterize the distributed capacitance of the impedance change region in the initial state and the initial equivalent inductance density distribution data to characterize the distributed inductance of the impedance change region in the initial state. The reverse parameter solving server is communicatively connected to the three-dimensional electromagnetic simulation module. It is used to calculate the target equivalent capacitance distribution matrix based on the preset target characteristic impedance and to calculate the three-dimensional equivalent dielectric constant requirement matrix. The CNC code compilation terminal is connected to the reverse parameter solving server and is used to call the preset equivalent medium theory algorithm to convert the three-dimensional equivalent dielectric constant requirement matrix into an air volume fraction matrix, and map the air volume fraction matrix into physical control parameters to generate multi-dimensional CNC machining code. A laser processing equipment is communicatively connected to the CNC code compilation terminal and is used to perform spatial gradient laser ablation on the PCB dielectric layer to be processed, which is composed of the PCB substrate, according to the multi-dimensional CNC processing code, so as to process a micro-air gap matrix containing internal air inside the PCB dielectric layer. A lamination apparatus is used to heat and press a dielectric layer having the micro-gap matrix with an insulating prepreg containing an interlayer bonding medium to a PCB laminate structure to be laminated. The damping effect formed by the thermal expansion of the internal air of the micro-gap matrix inhibits the penetration of molten resin generated by the heating of the insulating prepreg, so that the micro-gap matrix is ​​formed inside the cured PCB laminate structure.

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