Processing method of storage class PCB stepped gold finger structure and PCB board

Abstract

The application belongs to the technical field of PCB processing, and discloses a processing method of a storage type PCB ladder gold finger structure and a PCB. L1 / 4 layer sub-boards and L5 / 16 layer sub-boards are respectively laminated, and a gold finger is pasted with a protective film at the L5 layer; after the L1 / 4 layer sub-boards and the L5 / 16 layer sub-boards are laminated into L1 / 16, the ladder gold finger position is controlled in depth, and the PI protective film and a small amount of PP are removed in the remaining thickness by uncovering; two pieces of PP are pre-laminated at the L4 / 5 layer ladder gold finger position, including PP1 close to the L4 layer and PP2 close to the gold finger of the L5 layer; PP1 is pre-routed in a slotting way along the cutting size position of PP2, and PP2 is routed and slotted in a pre-routed slotting way. The ladder gold finger layer PP adopts different size slotting ways to reduce the dielectric thickness difference, and the depth control precision can be more accurate.

Description

Technical Field

[0001] This invention belongs to the field of PCB board processing technology, and particularly relates to a processing method and PCB board for a stepped gold finger structure of a storage PCB. Background Technology

[0002] The core advantages of PCB stepped gold finger boards (stepped gold fingers) are the overall strength of the thick board and the thin gold finger area, compatibility with standard slots, smooth insertion and removal, wear resistance and reliability, and stable signal. They are mainly used in high-density / high-speed / high-reliability / frequent insertion and removal scenarios, such as data centers and AI computing, 5G communication and network equipment, industrial automation and control, aerospace and military industries.

[0003] Currently, most stepped positions are produced by pre-spinning and laminating PP first, and then using a depth-controlled spindle method for the outer layer. With more layers, the thickness of the substrate varies and is uneven after lamination. In addition, the precision deviation of the depth-controlled spindle can cause damage to the surface of the gold fingers or the thickness of the gold fingers may not meet customer requirements. Based on the above analysis, the existing technology has the following problems and defects: Due to the precision issues of the depth control milling, excessive depth milling can easily occur, potentially milling into the gold fingers; conversely, insufficient depth milling results in excessive residual adhesive on the gold fingers, making it difficult to peel off the gold finger area. Using the same grooving method when stacking two PP sheets in a stepped gold finger layer will cause abnormally thin dielectric thickness in the gold finger area. Summary of the Invention

[0004] To overcome the problems existing in related technologies, the present invention discloses a method for processing a stepped gold finger structure for a storage PCB and a PCB board.

[0005] The technical solution is as follows: A method for processing a stepped gold finger structure for a storage PCB, comprising the following steps: S1, perform lamination of L1 / 4 layer sub-board and L5 / 16 layer sub-board respectively, and apply protective film to gold fingers on L5 layer; After S2, L1 / 4 layer sub-board and L5 / 16 layer sub-board are pressed together to form L1 / 16, the depth of the stepped gold finger position is controlled by milling. The PI protective film and PP are removed by peeling off the remaining thickness. The depth of the stepped gold finger position is controlled by milling 0.55mm, and the remaining 0.1mm thickness is removed by peeling off the remaining thickness. S3, two PP sheets are pre-stacked at the gold finger position of L4 / 5 layer, including PP1 near L4 layer and PP2 near L5 layer gold finger; PP1 is pre-grooved with a groove cutting method along the cutting size position of PP2, and PP2 is grooved and cut out using a pre-grooving method; the two PP sheets are 160μm thick, and PP1 is pre-grooved with a groove width of 0.5mm along the cutting size position of PP2.

[0006] In step S1, the lamination of the L1 / 4 layer sub-board and the L5 / 16 layer sub-board includes: laminating L2 / 3 into L1 / 4, fabricating the inner layer circuitry, making only the L4 layer circuitry on the L1 / 4 layer, making the normal inner layer circuitry on L6 / 7...L14 / 15, laminating into L5 / 16 layers, making only the L5 layer circuitry and gold fingers, silkscreening solder resist ink on the L5 layer and applying PI protective film to the gold fingers.

[0007] In step S2, the step-gold finger position control depth gong includes: S201, Automatic recording and compensation control of multi-point continuity depth; S202, Dynamic Flow Control and Stepped Groove Molding Optimization.

[0008] In step S201, the automatic recording and compensation control of multi-point conduction depth includes: using a router pin to run a router at multiple points in the blind slot area, and recording the depth value of the gold finger layer at each point when conduction occurs. The final gong depth is automatically calculated based on the preset compensation coefficient. The depth compensation formula is: In the formula, The depth of the gong after compensation. For the first Depth of the gong at the measuring point This is the process compensation value. This refers to the number of Gold Finger layers; Error correction formula: In the formula, This is the error correction value. For correction factor, For the maximum depth of the gong, Minimum depth of the gong; In step S202, dynamic adhesive flow control and stepped groove molding optimization include: in the lamination process, controlling the adhesive flow rate of the stepped groove by adjusting the prepreg size and windowing parameters. The windowing size formula is: In the formula, To determine the dimensions for deep milling of the window opening, For the required stepped groove dimensions, This refers to the size of the silicone pad.

[0009] In step S3, the pre-grooving method of cutting grooves along the dimensional position of PP2 by cutting PP1 includes: S301, high-precision positioning and path planning, achieves dynamic adjustment of the cutting path through a coordinate transformation formula, which is: In the formula, The offset of PP1 relative to PP2 is calibrated in real time using laser ranging, and the cutting path is aligned with the edge of PP2. This represents the displacement of PP1. This represents the displacement of PP2; The cutting feed speed is set using closed-loop control of a servo motor. , For cutting length, To adjust the speed dynamically using an improved PID algorithm, the groove width error is controlled within ±0.05mm. S302, laser cutting parameter optimization, groove width With laser power Cutting speed ,focal length The relationship is: In the formula, All are process coefficients; By monitoring thermal deformation during the cutting process in real time, the cutting path is dynamically corrected using a thermal compensation algorithm. The thermal compensation algorithm is as follows: In the formula, The change in temperature For cutting length, The coefficient of thermal expansion; S303, pre-stacked structure optimization, adds micron-level positioning pins or laser-drilled positioning holes between PP1 and PP2, positioning hole diameter With allowed offset The relationship is: In the formula, The diameter of the locating pin.

[0010] In step S301, during high-precision positioning and path planning, an improved PID algorithm is introduced to ensure the synchronization of cutting feed speed and offset correction: In the formula, For cutting feed speed, This is a scaling factor used to represent the current offset in a fast response. These are the integral coefficients, used to represent the elimination of long-term accumulated errors. The differential coefficient represents the suppression of oscillations caused by sudden shifts in offset. In step S302, real-time monitoring of thermal deformation during the cutting process includes: Step 1, Real-time monitoring of multimodal temperature field; A distributed fiber optic temperature sensor (DTS) and a high-speed infrared thermal imager are used for joint monitoring to achieve high-density and high-precision real-time acquisition of the temperature field in the cutting area; Temperature field interpolation formula: Discrete temperature points based on DTS A continuous temperature field is constructed using a cubic spline interpolation algorithm. : In the formula, These are interpolation basis functions used to achieve real-time temperature calculation at any point on the cutting path; Heat flux density calculation: Using Fourier's law of heat conduction, calculate the heat flux density of the cut region. : In the formula, The thermal conductivity of the material. For temperature gradient; Step 2: Real-time calculation of dynamic thermal deformation; Step 3: Real-time dynamic path correction.

[0011] In step 2, the real-time calculation of dynamic thermal deformation includes: Based on real-time temperature field data and the thermodynamic properties of the material, the thermal deformation of the cutting path is dynamically calculated; the cumulative thermal expansion formula divides the cutting process into small time steps. Calculate the thermal deformation increment for each step. : In the formula, For real-time temperature changes, This is the current cutting length. This is the initial cutting length; The total thermal deformation is obtained by integration: In the formula, This represents the total thermal deformation. Thermal stress correction formula: Considering the influence of material thermal stress on deformation, a correction factor is introduced. ; In the formula, This is the corrected thermal stress value. This is the initial value of thermal stress. It is the elastic modulus of the material, used to represent the correction of nonlinear deformation caused by thermal stress.

[0012] In step 3, real-time path dynamic correction includes: Based on the calculated thermal deformation, combined with the laser cutting path planning algorithm, the cutting trajectory is dynamically adjusted. Path offset compensation formula: This includes thermal deformation. Convert to cutting path offset ; In the formula, The angle between the cutting path and the thermal deformation direction is used to achieve real-time offset compensation of the cutting path. The cutting path is controlled by a PID closed-loop system, which dynamically adjusts the cutting parameters based on the predicted thermal deformation value and the actual monitoring value. In the formula, To dynamically adjust the cutting speed, The initial cutting speed is used, and the cutting parameters are adaptively adjusted through PID control. This represents the error caused by thermal deformation.

[0013] Another objective of this invention is to provide a high-end storage PCB board, which is manufactured using the aforementioned processing method for the stepped gold finger structure of a storage PCB. Combining all the above technical solutions, the beneficial effects of this invention are as follows: This invention solves the problem of gold finger damage caused by thickness differences at the stepped position and reduces the need for drilling at the depth control position. Improved product versatility: This stepped processing method is applicable to all products where the gold finger insertion / removal thickness exceeds the standard due to PCB thickness issues, avoiding damage to the gold fingers caused by the cumulative difference in drilling accuracy as the number of layers increases.

[0014] Excellent processing quality: The stepped gold finger layer PP uses different size slotting methods to reduce the thickness difference, which can make the depth control mill more accurate and avoid the depth control mill damaging the gold fingers and causing scrap. This can improve the yield and reduce production costs.

[0015] Strong process compatibility: This stepped gold finger processing technology is compatible with existing PCB mass production lines, without the need for additional dedicated production equipment, which greatly reduces the equipment investment cost and process upgrade difficulty for enterprises, facilitates large-scale mass production and improves production yield.

[0016] Electrical performance optimization: Addressing the high-speed, high-power requirements of AI servers, precise depth control effectively reduces impedance discontinuities caused by abrupt changes in the thickness of the gold finger dielectric. This enhances PCB signal integrity and anti-interference capabilities, meeting the stringent requirements of high-speed interconnect devices such as AI accelerator cards and 5G base station line cards.

[0017] Cost and efficiency balance: two PP sheets are pre-stacked in the stepped gold finger layer, and different sizes of pre-milled PP are used to reduce the difference in dielectric thickness at the gold finger position. Attached Figure Description

[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the disclosure of this invention and, together with the description, serve to explain the principles of this disclosure; Figure 1 This is a flowchart of the processing method for the stepped gold finger structure of a storage PCB provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of a 0.5mm wide groove pre-cut along the PP2 dimension position of PP1 provided in an embodiment of the present invention; Figure 3 The image shows the effect of pressing sub-boards L1 / 4 and L5 / 16 together to form L1 / 16 according to an embodiment of the present invention, with the stepped gold finger position controlled to a depth of 0.55mm, and the remaining 0.1mm thickness removed by a peeling method. Detailed Implementation

[0019] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0020] In Example 1, since the stepped gold finger position requires additional solder resist and PI protective film to protect the gold finger, stacking PP at this position would cause uneven dielectric thickness, resulting in damage to the gold finger during controlled-depth routing. However, by pre-stacking two PP sheets at the stepped gold finger position on layer L4 / 5 with different slot sizes, the dielectric thickness difference is reduced. The two PP sheets in this layer are pre-routed with slots (the PP sheet close to the gold finger is slotted and routed), and the other sheet is pre-routed using a slotting method.

[0021] like Figure 1 The processing method for the stepped gold finger structure of a storage PCB provided in this embodiment of the invention includes: S1, perform lamination of L1 / 4 layer sub-board and L5 / 16 layer sub-board respectively, and apply protective film to gold fingers on L5 layer; The lamination of L1 / 4 and L5 / 16 sub-boards is carried out separately: L2 / 3 is laminated into L1 / 4, inner layer circuitry is fabricated, L1 / 4 layer only has L4 layer circuitry, L6 / 7...L14 / 15 inner layer normal circuitry is laminated into L5 / 16 layer, only L5 layer circuitry and gold fingers are fabricated, solder resist ink is silkscreened on L5 layer and PI protective film is applied to gold fingers.

[0022] After S2, L1 / 4 layer sub-board and L5 / 16 layer sub-board are pressed together to form L1 / 16, the depth of the stepped gold finger position is controlled by milling. The PI protective film and PP are removed by peeling off the remaining thickness. The depth of the stepped gold finger position is controlled by milling 0.55mm, and the remaining 0.1mm thickness is removed by peeling off the remaining thickness. After the sub-boards L1 / 4 and L5 / 16 are pressed together to form L1 / 16, the depth of the stepped gold finger position is controlled at 0.55mm. The remaining 0.1mm thickness is removed by peeling off the cover (e.g. Figure 3 This reduces the problem of mechanical control causing damage to the gold fingers.

[0023] S3, two PP sheets are pre-stacked at the gold finger position of L4 / 5 layer, including PP1 near L4 layer and PP2 near L5 layer gold finger; PP1 is pre-grooved with a groove cutting method along the cutting size position of PP2, and PP2 is grooved and cut out using a pre-grooving method; the two PP sheets are 160μm thick, and PP1 is pre-grooved with a groove width of 0.5mm along the cutting size position of PP2.

[0024] The pre-grooving method for the grooving position is 0.5mm wide. PP2 uses the pre-grooving method to groove and cut out the groove.

[0025] The two PP sheets are 160μm thick. PP1 is pre-grooved with a 0.5mm wide groove along the dimensions of PP2 (e.g., ...). Figure 2 This avoids the problem of excessive thickness difference between the two PP sheets, which would not meet the requirements.

[0026] For example, in step S2, the stepped gold finger position control depth screw includes: S201, Automatic recording and compensation control of multi-point continuity depth; By using a gong probe to run the gong at multiple measurement points in the blind slot area, the depth value of the gold finger layer at each measurement point when it is conductive is recorded. The final gong depth is automatically calculated based on the preset compensation coefficient.

[0027] Depth compensation formula: In the formula, The depth of the gong after compensation. For the first Depth of the gong at the measuring point This is the process compensation value (dynamically adjusted based on substrate thickness and milling cutter wear, typically 0.02-0.05mm). This refers to the number of Gold Finger layers; Error correction formula: In the formula, This is the error correction value (usually taken as 0.5-0.8). For correction factor, For the maximum depth of the gong, Minimum depth of the gong; The above formula solves the problem of stepped depth deviation caused by uneven substrate thickness in traditional blind milling machines, improving the depth control accuracy to within ±0.02mm; automated recording and compensation reduce manual intervention, and the yield can be improved by 15%-20%.

[0028] S202, Dynamic Flow Control and Stepped Groove Molding Optimization; In the lamination process, the amount of adhesive flowing through the stepped grooves is controlled by adjusting the size of the prepreg and the windowing parameters. The formula for the windowing size is as follows: In the formula, To determine the dimensions for deep milling of the window opening, For the required stepped groove dimensions, This refers to the size of the silicone pad. This invention ensures no significant adhesive flow at the junction of the stepped groove walls, reducing adhesive flow by more than 50%; it also improves the flatness and conductivity of the stepped gold fingers, meeting the requirements of high-speed signal transmission.

[0029] Experimental verification. A comparative experiment on depth control accuracy showed that the traditional blind die-cutting process had a step depth deviation range of ±0.08-0.12mm and a yield of approximately 85%. The present invention controls the step depth deviation within ±0.02mm, increasing the yield to over 98%. In terms of accuracy control, existing blind die-cutting technologies suffer from large deviations and low yields; the present invention features multi-point automatic compensation, achieving a depth control accuracy of ±0.02mm. Regarding applicability, existing technologies struggle to meet the requirements of ultra-thin gold fingers; the present invention supports mass production of ultra-thin stepped gold fingers.

[0030] For example, in step S3, the pre-grooving method of cutting grooves along the dimensional position of PP2 by cutting PP1 includes: S301, high-precision positioning and path planning; employing a multi-axis linkage CNC system (such as a five-axis CNC) combined with laser scanning positioning technology, it achieves millimeter-level alignment between PP1 and PP2. Dynamic adjustment of the cutting path is achieved through a coordinate transformation formula; the coordinate transformation formula is: In the formula, The offset of PP1 relative to PP2 is calibrated in real time using laser ranging, and the cutting path is aligned with the edge of PP2. This represents the displacement of PP1. The displacement of PP2 is calculated by the laser ranging system, which scans the edge coordinates XPP2 of PP2 in real time, calculates the offset ΔX between PP1 and PP2, and dynamically corrects the cutting path coordinates XPP1 of PP1 to a value aligned with the edge of PP2. Compared to traditional fixed alignment holes or manual visual calibration, this formula achieves millimeter-level real-time dynamic compensation, solving the offset problem caused by PP thickness tolerance and thermal expansion during interlayer pre-stacking.

[0031] Precision control: Utilizing closed-loop control of a servo motor to set the cutting feed speed. , For cutting length, To adjust the speed dynamically using an improved PID algorithm, the groove width error is controlled within ±0.05mm. S302, optimized laser cutting parameters; using a high-precision laser cutting machine, stable processing of 0.5mm grooves is achieved through a three-parameter linkage model of power-speed-focal length.

[0032] groove width With laser power Cutting speed ,focal length The relationship is: In the formula, These are all process coefficients. After experimental calibration, the parameter combinations can be precisely adjusted to achieve the target width. Precision control: By monitoring thermal deformation during the cutting process in real time, the cutting path is dynamically corrected using a thermal compensation algorithm. The thermal compensation algorithm is as follows: In the formula, The change in temperature For cutting length, The coefficient of thermal expansion; S303, pre-stack structure optimization; micron-level positioning pins or laser-drilled positioning holes are added between PP1 and PP2, and inter-layer misalignment is reduced through a mechanical alignment-assisted CNC system. Positioning hole diameter. With allowed offset The relationship is: In the formula, The diameter of the locating pin.

[0033] Comparative Experiment: The traditional pre-routing process was compared with the innovative method described above. 100 samples were processed for each method, and the mean and standard deviation of the slot width were measured. Key Indicators: The mean slot width of the traditional process was 0.52mm, with a standard deviation of 0.08mm; the mean width of the method described in this invention was 0.50mm, with a standard deviation of 0.02mm, demonstrating a significant improvement in accuracy. Compared to traditional manual pre-routing or low-precision CNC cutting, this invention achieves high-precision, high-consistency processing of 0.5mm slots through multi-axis linkage, laser parameter optimization, and mechanical alignment, solving the slot misalignment problem caused by interlayer offset in stepped gold finger PP pre-stacking. The slot accuracy of existing PCB pre-stacking processes is typically ±0.1mm, while this invention can achieve ±0.05mm, meeting the stringent requirements of high-end PCBs for gold finger insertion and removal stability. Improved Production Efficiency: Automated positioning and cutting reduce manual intervention, shortening single-board processing time by more than 30%. Increased Yield: After improving slot accuracy, the gold finger insertion and removal defect rate decreased from 5% to 1%, significantly reducing scrap costs. Enhanced process stability: Through parameter modeling and real-time monitoring, the process exhibits high repeatability, adapting to mass production requirements. This invention achieves stable control of 0.5mm precision in pre-spinning the wire groove along PP2 by high-precision positioning, laser parameter optimization, and improved pre-stack structure. Compared to traditional processes, this invention demonstrates significant innovation and practicality, and can be widely applied in the manufacturing of high-end PCB stepped gold fingers.

[0034] For example, in step S301, to ensure the synchronization of the cutting feed speed and the offset correction, an improved PID algorithm is introduced: In the formula, For cutting feed speed, This is a scaling factor used to represent the current offset in a fast response. These are the integral coefficients, used to represent the elimination of long-term accumulated errors. The differential coefficient represents the suppression of oscillations caused by sudden changes in offset; this invention dynamically adjusts the cutting feed speed. This enables real-time tracking of the cutting path, controlling the groove width error within ±0.05mm.

[0035] Regarding alignment accuracy, traditional methods rely on fixed alignment holes or manual visual inspection, resulting in errors exceeding ±0.1mm. This invention, using laser ranging and PID control, achieves an error within ±0.05mm. In terms of process adaptability, existing technologies cannot handle offsets caused by PP thickness tolerances and thermal expansion. This invention provides real-time dynamic compensation, adapting to thickness tolerances within ±0.1mm. Regarding production efficiency, existing technologies require multiple manual calibrations, which are time-consuming. This invention automates calibration, reducing single-board processing time by over 30%. Regarding yield, existing technologies suffer from misalignment of wire grooves due to offsets, resulting in a defect rate of approximately 5%. This invention, with its improved accuracy, reduces the defect rate to below 1%.

[0036] Comparative Experiment: 100 samples were processed using both the traditional pre-layout process and the method of this invention, and the mean and standard deviation of the slot width were measured. The slot width error of this invention was reduced from ±0.1mm to ±0.05mm, meeting the stringent requirements of high-end PCBs for gold finger insertion and removal stability. Efficiency Optimization: Automated calibration reduces manual intervention, shortening single-board processing time by more than 30%, and significantly improving batch production consistency. Cost Reduction: The defect rate was reduced from 5% to 1%, scrap costs were reduced by 80%, and rework processes due to misalignment were reduced. This invention is applied to the pre-layout process of high-end HDI boards and stepped gold finger PCBs, solving problems such as slot misalignment and poor insertion / removal caused by interlayer misalignment in traditional processes, providing reliable technical support for the precision manufacturing of high-density interconnect circuit boards.

[0037] For example, in step S302, monitoring thermal deformation during the cutting process in real time includes: Step 1: Real-time monitoring of multimodal temperature field; using a distributed fiber optic temperature sensor (DTS) and a high-speed infrared thermal imager for joint monitoring to achieve high-density, high-precision real-time acquisition of the temperature field in the cutting area.

[0038] Temperature field interpolation formula: Discrete temperature points based on DTS A continuous temperature field is constructed using a cubic spline interpolation algorithm. : In the formula, These are interpolation basis functions used to achieve real-time temperature calculation at any point on the cutting path; Heat flux density calculation: Using Fourier's law of heat conduction, calculate the heat flux density of the cut region. : In the formula, The thermal conductivity of the material. The temperature gradient is used to predict thermal deformation trends. Compared with traditional point thermocouples, DTS plus infrared thermal imaging can cover the entire temperature field of the cutting path, improve the resolution to 0.1mm, and shorten the response time to 10ms, providing a high-precision data foundation for thermal deformation monitoring.

[0039] Step 2, Real-time Calculation of Dynamic Thermal Deformation: Based on real-time temperature field data and combined with the thermodynamic properties of the material, the amount of thermal deformation along the cutting path is dynamically calculated.

[0040] The cumulative thermal expansion formula divides the cutting process into tiny time steps. Calculate the thermal deformation increment for each step. : In the formula, For real-time temperature changes, This is the current cutting length. This is the initial cutting length; The total thermal deformation is obtained by integration: In the formula, This represents the total thermal deformation. Thermal stress correction formula: Considering the influence of material thermal stress on deformation, a correction factor is introduced. ; In the formula, This is the corrected thermal stress value. This is the initial value of thermal stress. is the elastic modulus of the material, used to represent the correction for nonlinear deformation caused by thermal stress. Dynamic tracking of thermal deformation is achieved through differential time step calculation; the thermal stress correction formula can compensate for the nonlinear thermal response of the material, reducing the thermal deformation prediction error from ±0.1mm to ±0.03mm.

[0041] Step 3, Real-time Path Dynamic Correction. Based on the calculated thermal deformation, and combined with the laser cutting path planning algorithm, the cutting trajectory is dynamically adjusted. Path offset compensation formula: [Calculate the thermal deformation amount...] Convert to cutting path offset ; In the formula, The angle between the cutting path and the thermal deformation direction is used to achieve real-time offset compensation of the cutting path. The cutting path is controlled by a PID closed-loop system, which dynamically adjusts the cutting parameters based on the predicted thermal deformation value and the actual monitoring value. In the formula, To dynamically adjust the cutting speed, The initial cutting speed is used, and the cutting parameters are adaptively adjusted through PID control. This represents the error caused by thermal deformation.

[0042] It is known that the path offset compensation formula can directly correct the cutting trajectory, avoiding misalignment of the groove caused by thermal deformation; the PID closed-loop control formula realizes real-time optimization of cutting parameters, improving processing stability. It is known that in terms of monitoring accuracy, existing point thermocouple technology has a resolution of 1mm and a response time of over 100ms; the present invention's DTS+infrared thermal imaging has a resolution of 0.1mm and a response time of 10ms. In terms of thermal deformation prediction error, existing technology is ±0.1mm; the present invention is ±0.03mm. In terms of path correction capability, existing technology cannot correct in real time and relies on preset compensation; the present invention uses dynamic offset compensation and PID parameter adjustment to correct the path in real time. In terms of process adaptability, existing technology is only suitable for low-speed cutting, with high errors at high speeds; the present invention is suitable for high-speed cutting (≥100mm / s) with stable error control.

[0043] Software platform: COMSOL Multiphysics is used for thermo-structural coupling simulation to simulate the temperature field and thermal deformation during laser cutting. Traditional point thermocouple monitoring with fixed compensation is used; this invention uses DTS (Digital Sensing and Thermodynamics) + infrared thermal imaging + dynamic correction. Key performance indicators: thermal deformation prediction error, groove width deviation, and cutting path offset.

[0044] Thermal deformation prediction error: The traditional method has an error of ±0.12mm, while the method of this invention has an error of ±0.025mm, improving accuracy by 83%. Groove width deviation: The traditional method has a deviation of ±0.15mm, while the method of this invention has a deviation of ±0.05mm, meeting the accuracy requirements for 0.5mm grooves. Cutting path offset: The traditional method has an offset of 0.2mm, while the method of this invention has an offset of 0.05mm, significantly reducing the risk of groove misalignment.

[0045] Actual cutting verification. Experimental conditions: A 100W UV laser cutting machine was used to cut PP material, with a target groove width of 0.5mm. The standard deviation of the groove width processed by the method of this invention was 0.018mm, while that of the traditional method was 0.065mm, increasing the yield rate from 85% to 98%. This invention is applied to the laser cutting process of stepped gold fingers on high-end PCBs, solving problems such as groove width deviation and poor insertion / removal caused by thermal deformation in traditional processes, providing reliable technical support for high-precision PCB manufacturing.

[0046] Example 2: High-end storage PCB board is fabricated using the method of Example 1.

[0047] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0048] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention and within the spirit and principles of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for fabricating a stepped gold finger structure for a storage-type PCB, characterized in that, This processing method Includes the following steps: S1, perform lamination of L1 / 4 layer sub-board and L5 / 16 layer sub-board respectively, and apply protective film to gold fingers on L5 layer; After S2, L1 / 4 layer sub-board and L5 / 16 layer sub-board are pressed together to form L1 / 16, the depth of the stepped gold finger position is controlled by milling. The PI protective film and PP are removed by peeling off the remaining thickness. The depth of the stepped gold finger position is controlled by milling 0.55mm, and the remaining 0.1mm thickness is removed by peeling off the remaining thickness. S3, two PP sheets are pre-stacked at the gold finger position of L4 / 5 layer, including PP1 near L4 layer and PP2 near L5 layer gold finger; PP1 is pre-grooved with a groove cutting method along the cutting size position of PP2, and PP2 is grooved and cut out using a pre-grooving method; the two PP sheets are 160μm thick, and PP1 is pre-grooved with a groove width of 0.5mm along the cutting size position of PP2.

2. The processing method of the stepped gold finger structure for storage PCBs according to claim 1, characterized in that, In step S1, the lamination of the L1 / 4 layer sub-board and the L5 / 16 layer sub-board includes: laminating L2 / 3 into L1 / 4, fabricating the inner layer circuitry, making only the L4 layer circuitry on the L1 / 4 layer, making the normal inner layer circuitry on L6 / 7...L14 / 15, laminating into L5 / 16 layers, making only the L5 layer circuitry and gold fingers, silkscreening solder resist ink on the L5 layer and applying PI protective film to the gold fingers.

3. The method for processing the stepped gold finger structure of a storage PCB according to claim 1, characterized in that, In step S2, the step-gold finger position control depth gong includes: S201, Automatic recording and compensation control of multi-point continuity depth; S202, Dynamic Flow Control and Stepped Groove Molding Optimization.

4. The processing method of the stepped gold finger structure for storage PCBs according to claim 3, characterized in that, In step S201, the automatic recording and compensation control of multi-point conduction depth includes: using a router pin to run a router at multiple points in the blind slot area, and recording the depth value of the gold finger layer at each point when conduction occurs. The final gong depth is automatically calculated based on the preset compensation coefficient. The depth compensation formula is: In the formula, The depth of the gong after compensation. For the first Depth of the gong at the measuring point This is the process compensation value. This refers to the number of Gold Finger layers; Error correction formula: In the formula, This is the error correction value. For correction factor, For the maximum depth of the gong, Minimum depth of the gong; In step S202, dynamic adhesive flow control and stepped groove molding optimization include: in the lamination process, controlling the adhesive flow rate of the stepped groove by adjusting the prepreg size and windowing parameters. The windowing size formula is: In the formula, To determine the dimensions for deep milling of the window opening, For the required stepped groove dimensions, This refers to the size of the silicone pad.

5. The processing method of the stepped gold finger structure for storage PCBs according to claim 1, characterized in that, In step S3, the pre-grooving method of cutting grooves along the dimensional position of PP2 by cutting PP1 includes: S301, high-precision positioning and path planning, achieves dynamic adjustment of the cutting path through a coordinate transformation formula, which is: In the formula, The offset of PP1 relative to PP2 is calibrated in real time using laser ranging, and the cutting path is aligned with the edge of PP2. This represents the displacement of PP1. This represents the displacement of PP2; The cutting feed speed is set using closed-loop control of a servo motor. , For cutting length, To adjust the speed dynamically using an improved PID algorithm, the groove width error is controlled within ±0.05mm. S302, laser cutting parameter optimization, groove width With laser power Cutting speed ,focal length The relationship is: In the formula, All are process coefficients; By monitoring thermal deformation during the cutting process in real time, the cutting path is dynamically corrected using a thermal compensation algorithm. The thermal compensation algorithm is as follows: In the formula, The change in temperature For cutting length, The coefficient of thermal expansion; S303, pre-stacked structure optimization, adds micron-level positioning pins or laser-drilled positioning holes between PP1 and PP2, positioning hole diameter With allowed offset The relationship is: In the formula, The diameter of the locating pin.

6. The method for processing the stepped gold finger structure of a storage PCB according to claim 5, characterized in that, In step S301, during high-precision positioning and path planning, an improved PID algorithm is introduced to ensure the synchronization of cutting feed speed and offset correction: In the formula, For cutting feed speed, This is a scaling factor used to represent the current offset in a fast response. These are the integral coefficients, used to represent the elimination of long-term accumulated errors. The differential coefficient represents the suppression of oscillations caused by sudden shifts in offset.

7. The method for processing the stepped gold finger structure of a storage PCB according to claim 5, characterized in that, In step S302, real-time monitoring of thermal deformation during the cutting process includes: Step 1, Real-time monitoring of multimodal temperature field; A distributed fiber optic temperature sensor (DTS) and a high-speed infrared thermal imager are used for joint monitoring to achieve high-density and high-precision real-time acquisition of the temperature field in the cutting area; Temperature field interpolation formula: Discrete temperature points based on DTS A continuous temperature field is constructed using a cubic spline interpolation algorithm. : In the formula, These are interpolation basis functions used to achieve real-time temperature calculation at any point on the cutting path; Heat flux density calculation: Using Fourier's law of heat conduction, calculate the heat flux density of the cut region. : In the formula, The thermal conductivity of the material. For temperature gradient; Step 2: Real-time calculation of dynamic thermal deformation; Step 3: Real-time dynamic path correction.

8. The method for processing the stepped gold finger structure of a storage PCB according to claim 7, characterized in that, In step 2, the real-time calculation of dynamic thermal deformation includes: Based on real-time temperature field data and the thermodynamic properties of the material, the thermal deformation of the cutting path is dynamically calculated; the cumulative thermal expansion formula divides the cutting process into small time steps. Calculate the thermal deformation increment for each step. : In the formula, For real-time temperature changes, This is the current cutting length. This is the initial cutting length; The total thermal deformation is obtained by integration: In the formula, This represents the total thermal deformation. Thermal stress correction formula: Considering the influence of material thermal stress on deformation, a correction factor is introduced. ; In the formula, This is the corrected thermal stress value. This is the initial value of thermal stress. It is the elastic modulus of the material, used to represent the correction of nonlinear deformation caused by thermal stress.

9. The method for processing the stepped gold finger structure of a storage PCB according to claim 8, characterized in that, In step 3, real-time path dynamic correction includes: Based on the calculated thermal deformation, combined with the laser cutting path planning algorithm, the cutting trajectory is dynamically adjusted. Path offset compensation formula: This includes thermal deformation. Convert to cutting path offset ; In the formula, The angle between the cutting path and the thermal deformation direction is used to achieve real-time offset compensation of the cutting path. The cutting path is controlled by a PID closed-loop system, which dynamically adjusts the cutting parameters based on the predicted thermal deformation value and the actual monitoring value. In the formula, To dynamically adjust the cutting speed, The initial cutting speed is used, and the cutting parameters are adaptively adjusted through PID control. This represents the error caused by thermal deformation.

10. A high-end storage PCB board, characterized in that, This high-end storage PCB is manufactured using the processing method of the stepped gold finger structure of the storage PCB as described in any one of claims 1-9.

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