A manufacturing method of HDI product using PTFE material

Abstract

This invention discloses a method for manufacturing HDI products using PTFE material, relating to the field of integrated circuit manufacturing. The method includes selecting a substrate, processing inner layer patterns, laminating to form a multilayer board, processing blind vias, removing adhesive from blind vias, metallizing and filling blind vias, and processing the outer layer patterns of the multilayer board to obtain the HDI product. This method employs a combined CO2 laser and picosecond laser process for processing blind vias. The CO2 laser efficiently forms blind vias, while the picosecond laser precisely removes residual adhesive from the bottom of the vias. The synergistic effect of these two processes solves the key problem of difficult adhesive removal during blind via processing on PTFE substrates. The overall process steps are tightly integrated, enabling stable fabrication of PTFE HDI products, improving conductivity, signal transmission performance, and structural stability, and providing a substrate processing solution for integrated circuit manufacturing.

Description

Technical Field

[0001] This invention relates to the field of integrated circuit manufacturing, and in particular to a method for manufacturing HDI products using PTFE material. Background Technology

[0002] High-density interconnect (HDI) products are widely used in high-end fields such as integrated circuit manufacturing due to their advantages of high density, high precision, and miniaturization. PTFE (polytetrafluoroethylene) material has excellent dielectric properties, resistance to high and low temperatures, and chemical stability, making it an ideal substrate for preparing high-frequency and high-speed HDI products.

[0003] However, the blind via fabrication process in HDI products using PTFE presents significant technical challenges, particularly in the production of high-precision HDI products for integrated circuit manufacturing. PTFE is an inert material, and after laser drilling, PTFE debris and adhesive residue from the decomposition of prepreg easily remain at the bottom of the blind via. Existing single laser drilling processes or conventional adhesive removal methods are ill-suited to the precision requirements of semiconductor device manufacturing equipment, failing to completely remove the adhesive residue. The presence of this residue severely impacts the bonding strength of subsequent via metallization, leading to decreased conductivity, increased signal transmission loss, and even issues such as via wall peeling and product failure. Summary of the Invention

[0004] The purpose of this invention is to provide a method for manufacturing HDI products using PTFE material, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for manufacturing HDI products using PTFE material, comprising the following steps:

[0006] S1. Select PTFE sheet as the substrate and process inner layer patterns on the substrate to form PTFE core board;

[0007] S2. A prepreg is pressed between the two PTFE core plates to form a multilayer board with PTFE core plates as the outer layer structure.

[0008] S3. Perform blind hole processing pretreatment on the multilayer board. After pretreatment, use a composite process that combines carbon dioxide laser drilling and picosecond laser removal of residual adhesive at the bottom of the blind hole to process the blind hole.

[0009] S4. Remove adhesive from the processed blind holes;

[0010] S5. After degumming, blind holes are sequentially subjected to hole metallization and hole filling processes.

[0011] S6. Process the outer layer pattern of the multilayer board to obtain the HDI product.

[0012] Preferably, the thickness of the PTFE sheet in step S1 is ≤0.15mm.

[0013] Preferably, the inner layer pattern in step S1 is fabricated using a hydrochloric acid etching process, wherein the concentration of the hydrochloric acid is 20%-40%, the etching temperature is 40℃-60℃, the spraying pressure is 1.0kg / cm²-2.0kg / cm², the etching speed is 5m / min-9m / min, and the line width / spacing of the inner layer pattern is 2mil-4mil.

[0014] Preferably, the blind hole machining pretreatment in step S3 adopts one of the following two methods:

[0015] Method 1: Based on the multilayer board, the outer surface copper is browned, and then the browned outer surface copper is subjected to a composite process of carbon dioxide laser drilling and picosecond laser removal of residual adhesive at the bottom of blind holes.

[0016] Method 2: The copper surface of the outer layer of the multilayer board where blind holes need to be processed is etched to form a substrate ring, exposing the PTFE substrate, and then a composite process of carbon dioxide laser drilling and picosecond laser removal of residual adhesive at the bottom of the blind hole is performed.

[0017] Preferably, in Method 1, the browning treatment of the outer layer of the multilayer board uses a browning solution composed of sulfuric acid and a bonding agent, wherein the bonding agent is A PLUS 65, the sulfuric acid concentration is 15%-25%, the bonding agent concentration is 40%-60%, the browning solution temperature is 25℃-35℃, the spraying pressure is 30kg / cm²-50kg / cm², and the treatment speed is 2.0m / min-3.0m / min.

[0018] Preferably, in Method 1, the thickness of the copper on the outer surface of the multilayer board that has been browned is 6μm-12μm.

[0019] Preferably, the pressing process parameters in step S2 are: pressing temperature 170℃-190℃, pressing pressure 20kg / cm²-30kg / cm², pressing time 60min-90min, and the pressing process adopts a stepped heating method with a heating rate of 2℃ / min-5℃ / min.

[0020] Preferably, the processing parameters for the carbon dioxide laser and picosecond laser in step S3 are as follows:

[0021] Carbon dioxide laser: aperture 2.5mm-3.0mm, energy 8mj-12mj, pulse width set in three stages, repeating 3-5 times in 8ms, 3-5 times in 6ms, and 3-5 times in 5ms.

[0022] Picosecond laser: power 50%-70%, speed 2500mm / s-3500mm / s, 1-3 sessions, frequency 200KHz-300KHz.

[0023] Preferably, the adhesive removal process in step S4 adopts a plasma adhesive removal process with an adhesive removal power of 300W-500W, an adhesive removal time of 30s-60s, and a residual adhesive thickness in the hole after adhesive removal ≤5μm.

[0024] Preferably, the hole metallization process in step S5 adopts a horizontal copper plating process, and the hole filling process adopts a hole filling electroplating process, so that the porosity of the copper layer in the blind hole after copper filling is ≤0.5%.

[0025] The technical effects and advantages of this invention are as follows:

[0026] 1. This method for manufacturing HDI products using PTFE material first selects PTFE sheet as the substrate. Inner layer patterns are then processed on the substrate to form a PTFE core board. Next, the PTFE core board is laminated with a prepreg to form a multilayer board with the PTFE core board as the outer layer. The multilayer board undergoes pretreatment before blind via processing. Then, a composite process combining CO2 laser drilling and picosecond laser removal of residual adhesive is used to process the blind vias. After specialized adhesive removal treatment of the blind vias, hole metallization and hole-filling electroplating processes are performed sequentially. Finally, the outer layer circuit pattern of the multilayer board is processed to obtain the HDI product. The composite process of CO2 laser and picosecond laser processing for blind vias allows for efficient blind via formation, while picosecond lasers precisely remove residual adhesive from the bottom of the vias. The synergistic effect of these two processes solves the key problem of difficult residue removal during blind via processing on PTFE substrates. The overall process steps are tightly integrated, enabling stable preparation of PTFE HDI products, improving the product's conductivity, signal transmission performance, and structural stability, and expanding the application scenarios of PTFE materials in high-end HDI products.

[0027] 2. In the method for manufacturing HDI products using PTFE material, two options are available in the blind hole processing pretreatment stage of step S3: Option 1 involves first browning the copper layer on the outer surface of the multilayer board, and then performing a composite laser drilling process; Option 2 involves first etching away the copper layer on the outer surface of the blind hole area to form a substrate ring and expose the PTFE substrate, and then performing a composite laser drilling process. These two targeted pretreatment schemes are provided to adapt to different processing requirements, improving the flexibility and applicability of the process. Both pretreatment methods can optimize the positioning accuracy of subsequent laser drilling, reduce the interference of the copper layer on laser energy, ensure the quality of blind hole forming and the effect of residual adhesive removal, and further improve the processing stability of the product.

[0028] 3. This method of manufacturing HDI products using PTFE material employs a stepped heating approach to avoid uneven curing of the prepreg, the generation of bubbles or internal stress caused by sudden temperature rises during the pressing process, thus ensuring the interlayer bonding strength of the multilayer board. Precise control of pressing temperature, pressure, and time ensures that the prepreg is fully cured, improving the structural density and stability of the multilayer board, reducing interlayer defects, and providing a high-quality substrate for subsequent blind via processing and circuit fabrication.

[0029] 4. This method for manufacturing HDI products using PTFE material achieves progressive forming of blind holes by gradient setting of the carbon dioxide laser pulse width, reducing thermal damage to the hole wall and improving the smoothness of the hole wall; precise matching of picosecond laser parameters can efficiently and accurately remove residual adhesive at the bottom of the hole without damaging the hole wall and surrounding substrate; the synergistic optimization of the two laser parameters further improves the processing quality and efficiency of blind holes, ensuring the dimensional accuracy, hole wall integrity and cleanliness of blind holes, laying a good foundation for subsequent processes. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0031] Figure 2 This is a schematic diagram of the product status in step S1 of the present invention;

[0032] Figure 3 This is a schematic diagram of the product status in step S2 of the present invention;

[0033] Figure 4 This is a schematic diagram of the product state using method one in step S3 of the present invention;

[0034] Figure 5 This is a schematic diagram of the product status in steps S4-S6 of the present invention;

[0035] Figure 6 This is a schematic diagram of the blind hole machining pretreatment state when using method two in step S3 of the present invention;

[0036] Figure 7 This is a schematic diagram of the blind hole machining state when using method two in step S3 of the present invention.

[0037] In the diagram: 1. PTFE core board; 2. Prepreg. Detailed Implementation

[0038] The technical solutions of 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.

[0039] This invention provides, for example Figures 1-7 The method shown includes the following steps for manufacturing HDI products using PTFE material:

[0040] S1. Select PTFE sheet as the substrate and process inner layer patterns on the substrate to form PTFE core board 1;

[0041] S2. A prepreg 2 is pressed between two PTFE core plates 1 to form a multilayer board with PTFE core plates 1 as the outer layer structure.

[0042] S3. Perform blind hole processing pretreatment on the multilayer board. After pretreatment, use a composite process that combines carbon dioxide laser drilling and picosecond laser removal of residual adhesive at the bottom of the blind hole to process the blind hole.

[0043] S4. Remove adhesive from the processed blind holes;

[0044] S5. After degumming, blind holes are sequentially subjected to hole metallization and hole filling processes.

[0045] S6. Process the outer layer pattern of the multilayer board to obtain the HDI product.

[0046] First, PTFE sheet is selected as the substrate. Inner layer patterns are processed on the substrate to form PTFE core board 1. Then, PTFE core board 1 and prepreg 2 are laminated together to form a multilayer board with PTFE core board 1 as the outer layer structure. Subsequently, the multilayer board undergoes pretreatment before blind via processing. Then, a composite process of CO2 laser drilling and picosecond laser removal of residual adhesive is used to process the blind vias. After specialized adhesive removal treatment of the blind vias, hole metallization and hole-filling electroplating processes are performed sequentially. Finally, the outer layer circuit pattern of the multilayer board is processed to obtain the HDI product. The composite process of CO2 laser and picosecond laser processing for blind vias allows for efficient blind via formation, while picosecond lasers precisely remove residual adhesive from the bottom of the vias. The synergistic effect of these two processes solves the key problem of difficult residue removal during blind via processing on PTFE substrates. The overall process steps are tightly integrated, enabling stable preparation of PTFE HDI products, improving the product's conductivity, signal transmission performance, and structural stability, and expanding the application scenarios of PTFE materials in high-end HDI products.

[0047] Furthermore, in step S1, the thickness of the PTFE sheet is ≤0.15mm.

[0048] Furthermore, in step S1, the inner layer pattern is fabricated using a hydrochloric acid etching process. The concentration of hydrochloric acid is 20%-40%, the etching temperature is 40℃-60℃, the spray pressure is 1.0kg / cm²-2.0kg / cm², the etching speed is 5m / min-9m / min, and the line width / spacing of the inner layer pattern is 2mil-4mil.

[0049] Furthermore, the blind hole machining pretreatment in step S3 adopts one of the following two methods:

[0050] Method 1: Based on the multilayer board, the outer surface copper is browned, and then the browned outer surface copper is subjected to a composite process of CO2 laser drilling and picosecond laser removal of residual adhesive at the bottom of blind holes.

[0051] Method 2: The copper surface of the outer layer of the multilayer board where blind holes need to be processed is etched to form a substrate ring, exposing the PTFE substrate. Then, a composite process of carbon dioxide laser drilling and picosecond laser removal of residual adhesive at the bottom of the blind holes is performed.

[0052] In the blind hole pretreatment stage of step S3, two optional methods are adopted: Method 1 is to first brown the copper layer on the outer surface of the multilayer board and then perform the composite laser drilling process; Method 2 is to first etch away the copper layer on the outer surface of the blind hole area to form a substrate ring and expose the PTFE substrate, and then perform the composite laser drilling process. Two targeted pretreatment schemes are provided to adapt to different processing requirements and improve the flexibility and applicability of the process. Both pretreatment methods can optimize the positioning accuracy of subsequent laser drilling, reduce the interference of the copper layer on the laser energy, ensure the blind hole forming quality and residual adhesive removal effect, and further improve the processing stability of the product.

[0053] Furthermore, in Method 1, the browning treatment of the outer layer of the multilayer board uses a browning solution composed of sulfuric acid and a bonding agent, with the bonding agent being A PLUS 65. The sulfuric acid concentration is 15%-25%, the bonding agent concentration is 40%-60%, the browning solution temperature is 25℃-35℃, the spraying pressure is 30kg / cm²-50kg / cm², and the treatment speed is 2.0m / min-3.0m / min.

[0054] Furthermore, in Method 1, the thickness of the copper on the outer surface of the multilayer board that has been browned is 6μm-12μm.

[0055] Furthermore, the process parameters for pressing in step S2 are as follows: pressing temperature 170℃-190℃, pressing pressure 20kg / cm²-30kg / cm², pressing time 60min-90min, and the pressing process adopts a stepped heating method with a heating rate of 2℃ / min-5℃ / min.

[0056] The stepped heating method can avoid the sudden temperature rise during the pressing process, which may cause uneven curing of the prepreg 2, air bubbles or internal stress, and ensure the interlayer bonding strength of the multilayer board. Precise control of the pressing temperature, pressure and time can ensure that the prepreg 2 is fully cured, improve the structural density and stability of the multilayer board, reduce interlayer defects, and provide a high-quality substrate for subsequent blind hole processing and circuit fabrication.

[0057] Furthermore, the processing parameters for the carbon dioxide laser and picosecond laser in step S3 are as follows:

[0058] Carbon dioxide laser: aperture 2.5mm-3.0mm, energy 8mj-12mj, pulse width set in three stages, repeating 3-5 times in 8ms, 3-5 times in 6ms, and 3-5 times in 5ms.

[0059] Picosecond laser: power 50%-70%, speed 2500mm / s-3500mm / s, 1-3 sessions, frequency 200KHz-300KHz.

[0060] By gradient-setting the pulse width of the carbon dioxide laser, progressive forming of blind holes can be achieved, reducing thermal damage to the hole wall and improving the smoothness of the hole wall. Precise matching of picosecond laser parameters can efficiently and accurately remove residual adhesive at the bottom of the hole without damaging the hole wall and surrounding substrate. The synergistic optimization of the two laser parameters further improves the processing quality and efficiency of blind holes, ensuring the dimensional accuracy, hole wall integrity and cleanliness of blind holes, laying a good foundation for subsequent processes.

[0061] Furthermore, in step S4, the adhesive removal process adopts plasma adhesive removal technology with a removal power of 300W-500W and a removal time of 30s-60s. After adhesive removal, the thickness of residual adhesive in the hole is ≤5μm.

[0062] Plasma adhesive removal technology has the advantages of high efficiency, precision, and non-destructiveness. It can further remove trace amounts of residual adhesive in blind holes, ensuring the cleanliness of the holes. By controlling the adhesive removal parameters to keep the residual adhesive thickness ≤5μm, the adhesion between the metal layer and the hole wall during the subsequent hole metallization process can be significantly improved, avoiding problems such as metal layer peeling and poor conductivity. At the same time, the range of process parameters can balance the adhesive removal effect and processing efficiency, reducing the impact on the substrate performance.

[0063] Furthermore, in step S5, the hole metallization process adopts a horizontal copper plating process, and the hole filling process adopts a hole filling electroplating process. After copper filling, the porosity of the copper layer in the blind hole is ≤0.5%.

[0064] The horizontal copper plating process can form a uniform and dense metal layer on the hole wall, ensuring the conductivity of the blind hole; the through-hole plating process can achieve complete filling of the blind hole, and controlling the porosity to ≤0.5% can avoid defects such as holes and voids, ensuring the conductivity and mechanical strength of the blind hole; this combination of processes can improve the reliability and stability of the blind hole, reduce signal transmission loss, and meet the performance requirements of high-frequency and high-speed HDI products.

[0065] First, PTFE sheet is selected as the substrate. Inner layer patterns are processed on the substrate to form PTFE core board 1. Then, PTFE core board 1 and prepreg 2 are laminated together to form a multilayer board with PTFE core board 1 as the outer layer structure. Subsequently, the multilayer board undergoes pretreatment before blind via processing. Then, a composite process of CO2 laser drilling and picosecond laser removal of residual adhesive is used to process the blind vias. After specialized adhesive removal treatment of the blind vias, hole metallization and hole-filling electroplating processes are performed sequentially. Finally, the outer layer circuit pattern of the multilayer board is processed to obtain the HDI product. The composite process of CO2 laser and picosecond laser processing for blind vias allows for efficient blind via formation, while picosecond lasers precisely remove residual adhesive from the bottom of the vias. The synergistic effect of these two processes solves the key problem of difficult residue removal during blind via processing on PTFE substrates. The overall process steps are tightly integrated, enabling stable preparation of PTFE HDI products, improving the product's conductivity, signal transmission performance, and structural stability, and expanding the application scenarios of PTFE materials in high-end HDI products.

[0066] As one implementation method, a composite laser process can be used to remove residual adhesive. However, the localized thermal sensitivity of PTFE material may lead to uneven removal of the adhesive, especially at the bottom edge of blind holes. This exposes a physical-level energy control defect—because the laser parameters are fixed, they cannot adapt to material variations, and residual adhesive may exceed the 5μm threshold, affecting subsequent metallization.

[0067] To address the potential issue of incomplete removal of residual adhesive at the bottom of blind holes after laser processing, this embodiment employs a combination of real-time thermal imaging and AI adaptive control to further refine the laser energy regulation process. Specifically, an infrared thermal imaging camera is integrated into the laser processing unit to monitor the temperature field during blind hole processing in real time. AI algorithms (such as deep learning models) are used to dynamically adjust the parameters (such as power and pulse width) of the carbon dioxide laser and picosecond laser to respond to the local thermal characteristics of the PTFE substrate. This system works in conjunction with the original composite laser process; when thermal imaging detects hot spots, it automatically reduces the laser energy or increases the number of picosecond laser scans to ensure uniform removal of residual adhesive.

[0068] The above embodiments control the residual adhesive thickness to ≤2μm, improve the smoothness of the hole wall by 30%, enhance the bonding force of blind hole metallization, and further reduce the signal transmission loss to 0.4dB / cm in the 28GHz band, thereby improving the high-frequency reliability of HDI products.

[0069] Example 1: Refer to Appendix Figures 2-5 The blind hole machining pretreatment in step S3 adopts method one, as detailed below:

[0070] S1: Substrate Selection and Inner Layer Patterning

[0071] Substrate selection: Select 0.12mm thick PTFE sheets as the core substrate, cut them to the preset size, and clean the surface (wipe with alcohol and air dry) for later use;

[0072] Inner layer pattern processing: The inner layer pattern is made using a hydrochloric acid etching process. A 30% hydrochloric acid etching solution is prepared, and the etching temperature is controlled at 50℃, the spray pressure at 1.5kg / cm², and the etching speed at 7m / min. After exposure and development, etching is performed to finally form a fine inner layer pattern with a line width / spacing of 3mil on the surface of the PTFE core board 1.

[0073] S2: Multilayer board lamination and pressing

[0074] Layer preparation: Use the PTFE core board 1 with the inner layer pattern made as the outer layer, set the PTFE core boards 1 on the top and bottom, and set the prepreg 2 in between. Stack the PTFE core board 1, prepreg 2 and PTFE core board 1 in the structure, and use positioning pins to ensure that the alignment deviation of each layer is ≤0.1mm.

[0075] Stepped pressing: The laminated structure is placed in a vacuum hot press and pressed using a stepped heating method. The specific parameters are set as follows: heating rate 3℃ / min, from room temperature to 180℃, maintaining pressing temperature at 180℃, pressing pressure 25kg / cm², pressing time 75min, and after pressing, it is naturally cooled to room temperature to form a multilayer board with a three-layer structure.

[0076] S3: Blind Hole Machining Pretreatment and Composite Laser Drilling

[0077] Blind via pretreatment - browning treatment: Prepare a composite browning solution with 20% sulfuric acid concentration and 50% bonding agent A PLUS 65 concentration. Control the browning solution temperature at 30℃, spray pressure at 40kg / cm², and processing speed at 2.5m / min. Feed the multilayer board into the browning equipment to brown the copper layer on its outer surface. After the treatment is completed, the thickness of the copper layer after browning is measured to be 9μm.

[0078] Composite laser blind hole processing:

[0079] CO2 laser drilling: Set the laser aperture to 2.8mm, energy to 10mj, and pulse width to three stages: 8ms repeated 4 times, 6ms repeated 4 times, and 5ms repeated 4 times. Drill holes at the preset blind hole positions on the multilayer board to form a preliminary blind hole structure.

[0080] Picosecond laser residue removal: Adjust the picosecond laser parameters to 60% power, 3000mm / s speed, 2 processing times, and 250KHz frequency. Perform laser scanning on the bottom of the initial blind hole to remove residual PTFE debris and semi-cured sheet residue.

[0081] S4: Special adhesive removal treatment for blind holes

[0082] The multilayer board processed by composite laser was placed into a plasma adhesive removal equipment. The adhesive removal power was set to 400W and the adhesive removal time to 45s. Special adhesive removal treatment was performed on blind holes. After the treatment, the thickness of residual adhesive in the hole was measured to be 3μm, which meets the requirements of subsequent processes.

[0083] S5: Blind via metallization and via filling

[0084] Hole metallization: A horizontal copper plating process is used to immerse the multilayer board in copper plating solution, control the copper plating temperature at 45℃ and the copper plating time at 15min, and deposit a uniform copper layer on the wall of the blind hole with a thickness of about 0.5μm.

[0085] Through-hole plating: A high-speed through-hole plating process is adopted. The plating solution is prepared and the plating current density is controlled at 3A / dm² and the plating temperature at 55℃. The blind holes are filled with copper. After the plating is completed, the porosity of the copper layer in the blind holes is found to be 0.3%.

[0086] S6: Outer layer graphic processing and finished product forming

[0087] Outer layer pattern processing: High-precision etching process is adopted. After exposure and development, the outer copper layer of the multilayer board is etched to create the preset outer layer circuit pattern, ensuring that the outer layer pattern and the inner layer pattern are accurately interconnected through blind vias.

[0088] Finished product processing: The multilayer board is subjected to solder resist, silkscreen printing, and shape cutting. After electrical performance testing (conductivity and insulation) and appearance inspection, high-performance PTFE substrate HDI products are obtained.

[0089] Example 2: Refer to Appendix Figures 6-7 In step S3, the blind hole pretreatment adopts method two. The only difference between this embodiment and embodiment 1 is the blind hole pretreatment method in step S3. The remaining steps and parameters are the same as in embodiment 1. The specific differences are as follows:

[0090] S3: Blind Hole Machining Pretreatment and Composite Laser Drilling

[0091] Blind via pretreatment - substrate ring etching: The predetermined area of ​​blind via is defined on the outer copper layer of the multilayer board through exposure and development processes. The surface copper layer of this area is etched away using ferric chloride etching solution to form a substrate ring with a width of 0.2mm around the blind via area, exposing the PTFE substrate underneath. After etching, the substrate is washed with water and air-dried.

[0092] Composite laser blind hole processing: The steps and parameters are the same as in Example 1, namely, carbon dioxide laser aperture of 2.8mm, energy of 10mj, and pulse width in three stages; picosecond laser power of 60%, speed of 3000mm / s, number of passes of 2, and frequency of 250KHz, to complete the blind hole forming and the removal of residual adhesive at the bottom of the hole in sequence.

[0093] The final HDI products were tested, and the products of Example 1 and Example 2 both met the requirements for high-frequency signal transmission. The blind via on-resistance was ≤5mΩ, and the signal transmission loss was ≤0.5dB / cm at 10GHz. The product qualification rate was high.

[0094] To further verify the high-frequency application performance of the product in this embodiment, a performance comparison was conducted in the 28GHz band between the product of this embodiment (implemented by HDI instead of PTFE, using Rogers 5880 material as an example) and the product using mechanical resin plugging process (using Rogers 5880 material as an example). The results are shown in the table below:

[0095]

[0096] First, PTFE sheet is selected as the substrate. Inner layer patterns are processed on the substrate to form PTFE core board 1. Then, PTFE core board 1 and prepreg 2 are laminated together to form a multilayer board with PTFE core board 1 as the outer layer structure. Subsequently, the multilayer board undergoes pretreatment before blind via processing. Then, a composite process of CO2 laser drilling and picosecond laser removal of residual adhesive is used to process the blind vias. After specialized adhesive removal treatment of the blind vias, hole metallization and hole-filling electroplating processes are performed sequentially. Finally, the outer layer circuit pattern of the multilayer board is processed to obtain the HDI product. The composite process of CO2 laser and picosecond laser processing for blind vias allows for efficient blind via formation, while picosecond lasers precisely remove residual adhesive from the bottom of the vias. The synergistic effect of these two processes solves the key problem of difficult residue removal during blind via processing on PTFE substrates. The overall process steps are tightly integrated, enabling stable preparation of PTFE HDI products, improving the product's conductivity, signal transmission performance, and structural stability, and expanding the application scenarios of PTFE materials in high-end HDI products.

[0097] The above data shows that the PTFE substrate HDI product prepared by the method of this embodiment has significantly better dielectric consistency, signal transmission loss and anti-crosstalk capability than the product prepared by the traditional mechanical resin plugging process at the 28GHz high frequency band, and is more suitable for the performance requirements of high-end scenarios such as 5G millimeter wave and high frequency communication.

[0098] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for manufacturing HDI products using PTFE material, characterized in that, Includes the following steps: S1. Select a PTFE sheet with a thickness of ≤0.15mm as the substrate, and process the inner layer pattern on the substrate to form a PTFE core board (1). S2. A prepreg (2) is pressed between two PTFE core plates (1) to form a multilayer board with PTFE core plates (1) as the outer layer structure; S3. Perform blind hole processing pretreatment on the multilayer board. After pretreatment, use a composite process combining carbon dioxide laser drilling and picosecond laser removal of residual adhesive at the bottom of the blind hole to process the blind hole. The blind hole processing pretreatment adopts one of the following two methods: Method 1: Based on the multilayer board, perform browning treatment on the outer surface copper; Method 2: Etch copper on the outer layer of the multilayer board at the location where blind holes need to be processed to form a substrate ring, exposing the PTFE substrate; The processing parameters for the composite process combining carbon dioxide laser drilling and picosecond laser removal of residual adhesive at the bottom of blind holes are as follows: Carbon dioxide laser: aperture 2.5mm-3.0mm, energy 8mj-12mj, pulse width set in three stages, repeating 3-5 times in 8ms, 3-5 times in 6ms, and 3-5 times in 5ms. Picosecond laser: power 50%-70%, speed 2500mm / s-3500mm / s, 1-3 sessions, frequency 200KHz-300KHz; S4. Remove adhesive from the processed blind holes; S5. After degumming, blind holes are sequentially subjected to hole metallization and hole filling processes. S6. Process the outer layer pattern of the multilayer board to obtain the HDI product.

2. The method for manufacturing HDI products using PTFE material according to claim 1, wherein, The inner layer pattern in step S1 is fabricated using a hydrochloric acid etching process. The concentration of the hydrochloric acid is 20%-40%, the etching temperature is 40℃-60℃, the spray pressure is 1.0kg / cm²-2.0kg / cm², the etching speed is 5m / min-9m / min, and the line width / spacing of the inner layer pattern is 2mil-4mil.

3. The method of claim 1, wherein the PTFE material is used to manufacture the HDI product. The browning treatment of the outer layer of the multilayer board described in Method 1 uses a browning solution composed of sulfuric acid and a bonding agent, wherein the sulfuric acid concentration is 15%-25%, the bonding agent concentration is 40%-60%, the browning solution temperature is 25℃-35℃, the spraying pressure is 30kg / cm²-50kg / cm², and the treatment speed is 2.0m / min-3.0m / min.

4. The method for manufacturing HDI products using PTFE material according to claim 1, wherein, In Method 1, the thickness of the copper on the outer surface of the multilayer board that has been browned is 6μm-12μm.

5. The method for manufacturing HDI products using PTFE material according to claim 1, wherein, The pressing process parameters in step S2 are as follows: pressing temperature 170℃-190℃, pressing pressure 20kg / cm²-30kg / cm², pressing time 60min-90min, and the pressing process adopts a stepped heating method with a heating rate of 2℃ / min-5℃ / min.

6. The method for manufacturing HDI products using PTFE material according to claim 1, wherein, The adhesive removal process described in step S4 uses plasma adhesive removal technology with a removal power of 300W-500W and a removal time of 30s-60s.

7. The method of claim 1, wherein the PTFE material is used to manufacture HDI products. The hole metallization process in step S5 adopts a horizontal copper plating process, and the hole filling process adopts a hole filling electroplating process.

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