Design method for inner-layer process edge formed by mixing and pressing different materials
By designing the detection module and pre-increase ratio coefficient on the inner copper foil process side of the PCB, the hierarchical alignment problem caused by mismatch in material shrinkage is solved, and effective control of inter-layer deviation is achieved.
Patent Information
- Application Number
- CN202510022840.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-07
- Publication Date
- 2025-05-09
AI Technical Summary
In PCB manufacturing, in the mixing process of high-speed or high-frequency materials and low-speed or low-frequency materials, the matching problem of the material causes the material to shrink differently after hot pressing, which in turn leads to the alignment problem between layers.
Detection modules such as concentric rings and punching targets are designed to conduct multiple detections and monitoring on the process edge of the inner copper foil, and different pre-increase ratio coefficients are given according to the shrinkage amount of the material at different stages to control the interlayer deviation of the product.
By this method, the interlayer deviation can be controlled within 75um after pressing, and the deviation of the drilling hole to the inner layer can be controlled within 3mil.
Smart Images
Figure CN119967728A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to PCB processing technology, and in particular to a method for designing inner layer process edges for mixed pressing of different materials. Background Art
[0002] Entering the 5G era, high-speed transmission is indispensable. Due to the high cost of high-speed materials, most of the processing choices for PCB manufacturing are based on economic considerations. High-speed materials and low-speed materials are mixed and matched for stacking design, or high-frequency materials such as PTFE, ceramic materials, etc., or high-speed materials such as modified resins and E-Glass, T-Glass or other glass materials are mixed and matched. The stacking design made by mixing different materials is very different in the actual processing and application of PCB products, which has a huge impact on the inter-layer alignment, drilling quality, degumming quality and yield of electrical performance testing of PCB boards. Therefore, it is necessary to conduct innovative research on such products to break through the problems of materials and matching, so that they are economical and feasible for mass production, so as to meet customer and market requirements.
[0003] The mixed pressing process of high-speed or high-frequency materials and low-speed or low-frequency is an inevitable technical route based on economic selection. The main problem is the matching of materials. After hot pressing, the materials show different shrinkage, which further leads to material deformation and alignment problems between layers. Summary of the invention
[0004] In order to overcome the above-mentioned defects, the present application provides a method for designing inner layer process edges for mixed pressing of different materials. This design method designs a variety of detection and monitoring modules such as concentric rings and punching targets on the inner copper foil, and gives different pre-expansion ratio coefficients according to the shrinkage amount of the material at different stages. The interlayer deviation of the final product after pressing can be controlled within 75um.
[0005] The technical solution adopted by this application to solve its technical problems is:
[0006] A method for designing inner layer process edges for mixed pressing of different materials includes the following steps:
[0007] Design concentric rings: Design three sets of concentric rings on the process edge of the inner copper foil of the circuit board, which are independent alignment concentric rings, first composite concentric rings and second composite concentric rings. The independent alignment concentric rings are independently designed for each layer of inner copper foil. The first composite concentric rings and the second composite concentric rings are mutually aligned between the inner copper foils of the same material. The independent alignment concentric rings are used for interlayer alignment detection after etching, the first composite concentric rings are used for alignment offset detection after riveting, and the second composite concentric rings are used for alignment offset detection after pressing;
[0008] Design punching targets: design two sets of X-RAY punching targets on the process edge of the inner copper foil, which are independent X-RAY punching targets and composite X-RAY punching targets. The independent X-RAY punching targets are independently designed for each layer of inner copper foil, and the composite X-RAY punching targets are for aligning the inner copper foils of the same material with each other. The independent X-RAY punching targets are used for detecting the expansion and contraction between layers after etching, and the composite X-RAY punching targets are used for detecting the alignment offset after lamination.
[0009] Optionally, a rivet target is designed on the process edge of the inner copper foil of the circuit board, and the rivet target is a cross mark with an inner diameter of 3.1 mm.
[0010] Optionally, a drilling coupon module for inner layer accuracy detection is designed on the process edge of the inner copper foil of the circuit board, with a 0.2-0.5mm through hole inside, and 2mil, 3mil, 4mil, and 5mil rings are designed on the inner layer of the hole.
[0011] Optionally, a hot melt block is designed on the process edge of the inner copper foil of the circuit board, the size of the inner block in the hot melt block is 9mm*24mm, and the distance between two adjacent inner blocks is 2.8mm.
[0012] Optionally, the circuit board is formed by pressing together multiple sub-boards, the sub-boards include two outer layer boards and at least one inner layer board, the inner layer board is located between the two outer layer boards, the copper foil layers on the outer layer boards include outer copper foil and inner copper foil, the copper foil layers on the inner layer boards are all inner copper foil, the outer layer boards include high-speed or high-frequency material boards, and the inner layer boards include low-speed or low-frequency material boards.
[0013] Optionally, the material of the outer layer board is TU-885SP, and the material of the inner layer board is TU-862-HF.
[0014] Optionally, the first composite concentric rings, the second composite concentric rings and the composite X-RAY punching target corresponding to each other are designed on the inner copper foil of the outer layer board, and the first composite concentric rings, the second composite concentric rings and the composite X-RAY punching target corresponding to each other are designed on the inner copper foil of the inner layer board. When designing the first composite concentric rings, the second composite concentric rings and the composite X-RAY punching target, the pre-expansion ratio is set according to the materials of the outer layer board and the inner layer board.
[0015] Optionally, when designing the first composite concentric rings on the inner copper foil of the outer layer board, the pre-expansion ratios adopted are X=1.0007 and Y=1.0066, and when designing the first composite concentric rings on the inner copper foil of the inner layer board, the pre-expansion ratios adopted are X=1.00065 and Y=1.0005; when designing the second composite concentric rings and the composite X-RAY punching target on the inner copper foil of the outer layer board, the pre-expansion ratios adopted are X=1.00133 and Y=1.0012, and when designing the second composite concentric rings and the composite X-RAY punching target on the inner copper foil of the inner layer board, the pre-expansion ratios adopted are X=1.00065 and Y=1.0005.
[0016] The beneficial effects of the present application are as follows: in the present application, for high-speed materials with large dimensional shrinkage and low-speed materials with small shrinkage, that is, materials with a shrinkage difference of 500-1500ppm, independent rings for interlayer alignment detection after etching, namely independent alignment concentric rings, independent targets for interlayer expansion and contraction measurement after etching, namely independent X-RAY punching targets, rivet punching targets, rivet hole targets, concentric rings for alignment offset detection after riveting, namely the first composite concentric rings, concentric rings for alignment offset detection after pressing, namely the second composite concentric rings, X-RAY drilling target offset detection targets after pressing, namely the composite X-RAY punching targets, enlarged hot melt blocks, coupon modules for drilling inner layer accuracy detection, and other production and control detection and monitoring modules are designed respectively on the edge of their processing technology, and different pre-expansion ratio coefficients are given according to the shrinkage of the materials at different stages, so that the interlayer deviation of the final product after pressing can be controlled within 75um; the drilling inner layer deviation is controlled within 3mil. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 This is a schematic diagram of the structure of the circuit board in this application. DETAILED DESCRIPTION
[0018] The following will be combined with the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.
[0019] A method for designing inner layer process edges for mixed pressing of different materials includes the following steps:
[0020] Design concentric rings: design three sets of concentric rings on the process edge of the inner copper foil of the circuit board, which are independent alignment concentric rings, first composite concentric rings and second composite concentric rings. The independent alignment concentric rings are independently designed for each layer of inner copper foil. The first composite concentric rings and the second composite concentric rings are mutually aligned between inner copper foils of the same material. The independent alignment concentric rings are used for interlayer alignment detection after etching, the first composite concentric rings are used for alignment offset detection after riveting, and the second composite concentric rings are used for alignment offset detection after pressing. After riveting, the MH concentric rings, i.e., the first composite concentric rings, can be detected to confirm whether there is a riveting layer deviation problem. After pressing, the second composite concentric rings can be detected to confirm the interlayer alignment offset direction after lamination.
[0021] Design punching targets: design two sets of X-RAY punching targets on the process edge of the inner copper foil, which are independent X-RAY punching targets and composite X-RAY punching targets. The independent X-RAY punching targets are independently designed for each layer of inner copper foil, and the composite X-RAY punching targets are for aligning the inner copper foils of the same material with each other. The independent X-RAY punching targets are used for detecting the expansion and contraction between layers after etching, and the composite X-RAY punching targets are used for detecting the alignment offset after lamination.
[0022] In the present application, for high-speed materials with large dimensional shrinkage and low-speed materials with small shrinkage, that is, materials with a shrinkage difference of 500-1500ppm, various production and control detection and monitoring modules are designed on the edge of their processing technology, including independent rings for interlayer alignment detection after etching, namely independent alignment concentric rings, independent targets for interlayer expansion and contraction measurement after etching, namely independent X-RAY punching targets, rivet punching targets, rivet hole targets, concentric rings for alignment offset detection after riveting, namely the first composite concentric rings, concentric rings for alignment offset detection after pressing, namely the second composite concentric rings, target for X-RAY drilling target offset detection after pressing, namely the composite X-RAY punching target, enlarged hot melt blocks, coupon modules for drilling inner layer accuracy detection, and other production and control detection and monitoring modules, and three different pre-increase ratio coefficients are given according to the shrinkage of the materials at different stages. The interlayer deviation of the final product after pressing can be controlled within 75um; the drilling inner layer deviation is controlled within 3mil.
[0023] A rivet target is designed on the process edge of the inner copper foil of the circuit board. The rivet target is a cross mark with an inner diameter of 3.1mm. The cross mark monitors the deviation of the rivet hole. In the drilling process, a rivet explosion-proof hole with an inner diameter of 5.0mm is added. The pressed rivets are cut off, and 5-10 explosion-proof holes are drilled on the periphery.
[0024] A coupon module for drilling inner layer accuracy detection is designed on the process edge of the inner copper foil of the circuit board, with a 0.2-0.5mm through hole inside, and 2mil, 3mil, 4mil, and 5mil rings are designed on the inner layer of the hole. The maximum value setting needs to be 1.5mil smaller than the inner hole to copper single side of the PCS functional via hole. For example, the functional via hole to copper in the inner PCS is 8mil, and the maximum ring of the coupon module is designed to be 5mil.
[0025] A hot melt block is designed on the process edge of the inner copper foil of the circuit board. The size of the inner block in the hot melt block is 9mm*24mm, and the distance between two adjacent inner blocks is 2.8mm. The hot melt block design is optimized from the current 7*20mm spacing of 4mm to the inner block of 9*24mm, and the melting spacing of 2.8mm is shortened to reduce the spacing after hot melting and expand the fusion area of the resin and the copper layer after hot melting.
[0026] The circuit board is formed by laminating a plurality of sub-boards, the sub-boards include two outer-layer boards and at least one inner-layer board, the inner-layer board is located between the two outer-layer boards, the copper foil layers on the outer-layer boards include outer-layer copper foil and inner-layer copper foil, the copper foil layers on the inner-layer boards are all inner-layer copper foil, the outer-layer boards include high-speed or high-frequency material boards, and the inner-layer boards include low-speed or low-frequency material boards. The material of the outer-layer boards is TU-885SP, and the material of the inner-layer boards is TU-862-HF.
[0027] The first composite concentric rings, the second composite concentric rings and the composite X-RAY punching target are designed to correspond to each other on the inner copper foil of the outer layer board, and the first composite concentric rings, the second composite concentric rings and the composite X-RAY punching target are designed to correspond to each other on the inner copper foil of the inner layer board. When designing the first composite concentric rings, the second composite concentric rings and the composite X-RAY punching target, the pre-expansion ratio is set according to the materials of the outer layer board and the inner layer board.
[0028] When designing the first composite concentric rings on the inner copper foil of the outer layer board, the pre-expansion ratios adopted are X=1.0007 and Y=1.0066; when designing the first composite concentric rings on the inner copper foil of the inner layer board, the pre-expansion ratios adopted are X=1.00065 and Y=1.0005; when designing the second composite concentric rings and the composite X-RAY punching target on the inner copper foil of the outer layer board, the pre-expansion ratios adopted are X=1.00133 and Y=1.0012; when designing the second composite concentric rings and the composite X-RAY punching target on the inner copper foil of the inner layer board, the pre-expansion ratios adopted are X=1.00065 and Y=1.0005.
[0029] Embodiment 1:
[0030] 1. Description of the stacking structure, such as Figure 1 As shown, this embodiment is a ten-layer circuit board formed by laminating five sub-boards, the five boards include two high-speed material boards and three low-speed material boards, after lamination, the three low-speed material boards are located between the two high-speed material boards, the copper foil layers on one of the high-speed material boards are defined as L1 and L2, the copper foil layers on the other high-speed material board are defined as L9 and L10, and the copper foils of the three low-speed material boards are defined as L3 and L4, L5 and L6, L7 and L8 in sequence; L1 and L10 are outer copper foils, L2 and L9 are inner copper foils, L3, L4, L5, L6, L7, L8 are all inner copper foils, and different boards are laminated by prepregs;
[0031] Among them, the L1-L2 layer and L9-L10 layer, i.e. the high-speed material plate, are made of TU-885SP material, model: 0.076mmH / Hoz; the dimensional stability standard is: radial: -880PPM, weft: -950ppm;
[0032] The L3-L4, L5-L6, L7-L8 layers, i.e. the low-speed material plates, are made of TU-862-HF material, model: 0.15mm 1 / 1oz; the dimensional stability standards are: radial: +75PPM, weft: +125ppm.
[0033] The theoretical shrinkage difference between the two materials is 955ppm in the radial direction and 1075ppm in the latitudinal direction, and the material shrinkage is seriously mismatched.
[0034] For the stacking design of different materials, due to the inherent CTE expansion and contraction characteristics between the materials, it presents different shrinkage characteristics at different stages. In the actual PCB production and processing process, different production control schemes are also required at different stages to ensure the quality of inter-layer offset is controlled.
[0035] 2. Process
[0036] Cutting → Inner layer → Inner layer AOI → Lamination → High cutting and grinding → Drilling → Plasma degumming → Horizontal PTH → Pulse plating → Resin plugging → High cutting and grinding 1 → Cover hole plating → Dry film → Etching → Mid-term inspection AOI → Solder mask → Gold plating → Text → Molding → Testing → Visual inspection → Packaging
[0037] 3. Design and processing instructions of process edge
[0038] The theoretical shrinkage of two different materials is quite different, 955ppm in radial direction and 1075ppm in latitudinal direction, and the shrinkage of materials is seriously mismatched. Using normal process, or only designing different pre-release ratios, there are uncontrolled problems in the three stages of expansion and contraction and layer deviation monitoring after inner layer etching, interlayer monitoring during riveting, and interlayer monitoring during pressing, so the following process innovation design and process improvement are made.
[0039] 1. Design 3 sets of independent visual inter-layer alignment detection concentric rings at the process edge:
[0040] The first set: L2 and L9 layers are independently aligned with concentric rings, and all other layers are opened, that is, the corresponding positions of other layers are hollowed out of copper;
[0041] The L3-L4-L5-L6-L7-L8 layers are independently aligned with concentric rings, and all other layers are opened.
[0042] Note: Because the materials used in the L2 and L9 layers have the same shrinkage, and the materials used in the L3-L4-L5-L6-L7-L8 layers have the same shrinkage, the design is to detect the inter-layer alignment deviation independently.
[0043] The second set: Design the first composite concentric ring on the L2 and L9 layers, with the pre-expansion ratio of X=1.0007Y=1.0066, pre-shrink first, then expand together, and mark the words MH on the L2 and L9 layers;
[0044] The first composite concentric ring is designed for the L3-L4-L5-L6-L7-L8 layers, with the pre-increase ratio being: X=1.00065, Y=1.0005.
[0045] Note: Due to the different shrinkage amounts after etching, a set of concentric rings are designed for all layers of L2-L3-L4-L5-L6-L7-L8-L9, giving the L2-L9 layer a larger pre-increase ratio than the L3-L4-L5-L6-L7-L8 layer, to monitor the inter-layer alignment matching after etching and riveting.
[0046] The third set: The second composite concentric rings are designed for L2 and L9 layers, with the pre-increase ratio: X=1.00133, Y=1.0012, pre-shrinking first, and then pre-increase, the second composite concentric rings are designed for L3-L4-L5-L6-L7-L8 layers, X=1.00065, Y=1.0005.
[0047] Note: Due to the different shrinkage amounts after pressing, a set of concentric rings are designed for all layers of L2-L3-L4-L5-L6-L7-L8-L9, giving the L2-L9 layers a larger pre-expansion ratio than the L3-L4-L5-L6-L7-L8 layers, to monitor the alignment and matching issues between the layers after pressing.
[0048] 2. Design 2 sets of pressed X-RAY punching targets
[0049] The first set: L2 and L9 layers are equipped with independent X-RAY punching targets, and all other layers are set open to facilitate the measurement of the expansion and contraction of the TU-885sp material after pressing;
[0050] The L3-L4-L5-L6-L7-L8 layers are equipped with independent X-RAY punching targets, and the other layers are all opened to facilitate the measurement and grasping of the expansion and contraction of the TU-862-HF material after pressing.
[0051] Note: Since the materials used in the L2 and L9 layers have the same shrinkage, and the materials used in the L3-L4-L5-L6-L7-L8 layers have the same shrinkage, an independent X-RAY punching target is designed to detect the shrinkage data of X1\X2 and Y1\Y2 after lamination. The pre-expansion ratio of the inner layer is inferred based on the shrinkage data.
[0052] The second set: L2 and L9 layers are designed with a composite X-RAY punching target, with a pre-expansion ratio of X=1.00133, Y=1.0012, pre-shrinking first, and then expanding together; L3-L4-L5-L6-L7-L8 layers are designed with a composite X-RAY punching target, X=1.00065, Y=1.0005;
[0053] Note: Due to the different shrinkage amounts after pressing, a set of X-RAY punching targets for all layers of L2-L3-L4-L5-L6-L7-L8-L9 is designed, giving the L2-L9 layer a larger pre-expansion ratio than the L3-L4-L5-L6-L7-L8 layer, and monitoring the inter-layer offset of the X-RAY drilling target processing after pressing.
[0054] 3. Design rivet targets
[0055] A rivet target is designed on the process edge of the inner copper foil of the circuit board. The rivet target is a cross mark with an inner diameter of 3.1mm. The cross mark monitors the deviation of the rivet hole. Rivet explosion-proof holes with an inner diameter of 5.0mm are added to the drilling process. The pressed rivets are cut off, and 5-10 explosion-proof holes are drilled on the periphery.
[0056] 4. Design coupon module
[0057] The coupon module is designed on the process edge of the inner copper foil of the circuit board, and the coupon module is drilled to detect the inner layer accuracy. A 0.2-0.5mm through hole is set inside, and 2mil, 3mil, 4mil, and 5mil rings are designed on the inner layer of the hole. The maximum value setting needs to be 1.5mil smaller than the inner hole to copper single side of the PCS functional via hole. For example, the functional via hole to copper in the inner PCS is 8mil, and the maximum ring design of the coupon module is 5mil.
[0058] 5. Design hot melt block
[0059] A hot melt block is designed on the process edge of the inner copper foil of the circuit board, and the design of the hot melt block is optimized, from the current 7*20mm spacing of 4mm, optimized to the inner block 9*24mm, the melting spacing of 2.8mm to reduce the spacing after hot melting and expand the fusion area of the resin and the copper layer after hot melting.
[0060] 6. The punching target point of the rivet hole and the target of the rivet hole are given a pre-expansion ratio: X=1.0007, Y=1.0066, pre-shrink first, then expand simultaneously.
[0061] 7. For the L2 and L9 high-speed material layers, the design ratio of the circuit graphics within the board is: X=1.00133, Y=1.0012; for the L3-L4-L5-L6-L7-L8 low-speed material layers, the design ratio of the circuit graphics within the board is: X=1.00065, Y=1.0005.
[0062] 8. After the inner layer is etched, the expansion and contraction are measured. L1-L2, L9-L10 and L3-L4, L5-L6, L7-L8 are controlled separately with different shrinkage amounts, and the core thickness specification of 0.15mm is used as the control standard: L1-L2, L9-L10: control standard: X pre-expansion +10mil Y pre-expansion +14mil; L3-L4, L5-L6, L7-L8: control standard: single point edge within 3mil, R value within 2mil.
[0063] 9. Carry out batch testing on TU-885SP [0.076mm H / H] and TU-862-HF [0.15mm 1 / 1] for dimensional stability, and record and track the differences between batches. If the expansion and contraction between batches are unstable, the leading batch should be tested to obtain the expansion and contraction between layers after lamination, so as to adjust the preventive proportional coefficient for the inner layer, and control the dimensional stability within the range of ±150ppm.
[0064] 10. The press-fit riveting is done by first hot-melting 12 points and then using an 8-axis riveting machine for composite riveting. The 8-axis rivets are riveted simultaneously, using machined rivets with specifications of: 3.8mm long, 3.175mm wide, and 2.2mm high.
[0065] 4. Results Analysis
[0066] 1. After etching, the interlayer expansion and contraction stability of different materials after etching is measured by independently aligning the center circle ring to ensure that the shrinkage of different materials after etching is controlled and stable. The dimensional stability of the material can be detected simultaneously and can be controlled within ±150ppm;
[0067] 2. After riveting, the MH concentric ring, i.e. the first composite concentric ring, can be detected to confirm whether there is a riveting layer deviation problem;
[0068] 3. After lamination, the composite X-RAY target can be detected by X-RAY to confirm the offset after lamination;
[0069] 4. After lamination, the second composite concentric ring can be detected to confirm the offset direction of the inter-layer alignment after lamination;
[0070] 5. After lamination, the X-RAY targets of independent layers can be inspected by X-RAY, and the shrinkage after lamination can be captured for layer deviation problems, and then the inner layer pre-release ratio coefficient can be inferred based on different shrinkage amounts;
[0071] 6. After lamination, the interlayer deviation can be controlled within 75um; L2, L3, L4, and L5 layer deviation monitoring coupons can be used to detect the accuracy of drilling between inner layers, and the deviation of drilling between inner layers can be controlled within 3mil.
[0072] For high-speed materials with large dimensional shrinkage and low-speed materials with small shrinkage, that is, materials with a shrinkage difference of 500-1500ppm, the present application designs a variety of production and control detection and monitoring modules on the edge of their processing technology, including independent rings for interlayer alignment detection after etching, namely independent alignment concentric rings, independent targets for measuring interlayer expansion and contraction after etching, namely independent X-RAY punching targets, rivet punching targets, rivet hole targets, concentric rings for detecting alignment offset after riveting, namely the first composite concentric rings, concentric rings for detecting alignment offset after pressing, namely the second composite concentric rings, target for detecting X-RAY drilling target offset after pressing, namely the composite X-RAY punching target, enlarged hot melt blocks, coupon modules for detecting inner layer accuracy of drilling, and three different pre-expansion ratio coefficients are given according to the shrinkage of the materials at different stages. The interlayer deviation of the final product after pressing can be controlled within 75μm; the deviation of drilling to the inner layer is controlled within 3mil.
[0073] It should be noted that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present application, and these modifications and improvements are all within the scope of protection of the present application. Therefore, the scope of protection of the patent of the present application shall be subject to the attached claims.
Claims
1. A method for designing inner layer process edges for mixed pressing of different materials, characterized by: The steps include: Design concentric rings: Design three sets of concentric rings on the process edge of the inner copper foil of the circuit board, which are independent alignment concentric rings, first composite concentric rings and second composite concentric rings. The independent alignment concentric rings are independently designed for each layer of inner copper foil. The first composite concentric rings and the second composite concentric rings are mutually aligned between the inner copper foils of the same material. The independent alignment concentric rings are used for interlayer alignment detection after etching, the first composite concentric rings are used for alignment offset detection after riveting, and the second composite concentric rings are used for alignment offset detection after pressing; Design punching targets: design two sets of X-RAY punching targets on the process edge of the inner copper foil, which are independent X-RAY punching targets and composite X-RAY punching targets. The independent X-RAY punching targets are independently designed for each layer of inner copper foil, and the composite X-RAY punching targets are for aligning the inner copper foils of the same material with each other. The independent X-RAY punching targets are used for detecting the expansion and contraction between layers after etching, and the composite X-RAY punching targets are used for detecting the alignment offset after lamination.
2. The method for designing inner layer process edge of mixed pressing of different materials according to claim 1, characterized in that: A rivet target is designed on the process edge of the inner copper foil of the circuit board, and the rivet target is a cross mark with an inner diameter of 3.1 mm.
3. The method for designing inner layer process edge of mixed pressing of different materials according to claim 1, characterized in that: A drilling coupon module for inner layer accuracy detection is designed on the process edge of the inner copper foil of the circuit board, with 0.2-0.5mm through holes inside, and 2mil, 3mil, 4mil, and 5mil rings are designed on the inner layer of the hole.
4. The method for designing inner layer process edge of mixed pressing of different materials according to claim 1, characterized in that: A hot melt block is designed on the process edge of the inner copper foil of the circuit board. The size of the inner block in the hot melt block is 9mm*24mm, and the distance between two adjacent inner blocks is 2.8mm.
5. The method for designing inner layer process edge of mixed pressing of different materials according to claim 1, characterized in that: The circuit board is formed by pressing together multiple sub-boards, the sub-boards include two outer-layer boards and at least one inner-layer board, the inner-layer board is located between the two outer-layer boards, the copper foil layers on the outer-layer boards include outer-layer copper foil and inner-layer copper foil, the copper foil layers on the inner-layer boards are all inner-layer copper foil, the outer-layer boards include high-speed or high-frequency material boards, and the inner-layer boards include low-speed or low-frequency material boards.
6. The method for designing inner layer process edge of mixed pressing of different materials according to claim 5, characterized in that: The material of the outer layer plate is TU-885SP, and the material of the inner layer plate is TU-862-HF.
7. The method for designing inner layer process edge of mixed pressing of different materials according to claim 5, characterized in that: The first composite concentric rings, the second composite concentric rings and the composite X-RAY punching target are designed to correspond to each other on the inner copper foil of the outer layer board, and the first composite concentric rings, the second composite concentric rings and the composite X-RAY punching target are designed to correspond to each other on the inner copper foil of the inner layer board. When designing the first composite concentric rings, the second composite concentric rings and the composite X-RAY punching target, the pre-expansion ratio is set according to the materials of the outer layer board and the inner layer board.
8. The method for designing inner layer process edge of mixed pressing of different materials according to claim 7, characterized in that: When designing the first composite concentric rings on the inner copper foil of the outer layer board, the pre-expansion ratios adopted are X=1.0007 and Y=1.0066; when designing the first composite concentric rings on the inner copper foil of the inner layer board, the pre-expansion ratios adopted are X=1.00065 and Y=1.0005; when designing the second composite concentric rings and the composite X-RAY punching target on the inner copper foil of the outer layer board, the pre-expansion ratios adopted are X=1.00133 and Y=1.0012; when designing the second composite concentric rings and the composite X-RAY punching target on the inner copper foil of the inner layer board, the pre-expansion ratios adopted are X=1.00065 and Y=1.0005.