Manufacturing method of high-heat-dissipation and high-current-carrying integrated copper-embedded block circuit board and circuit board

Abstract

A method for manufacturing a high-heat-dissipation, high-current-carrying integrated copper-embedded circuit board and the circuit board itself are disclosed to solve the problem of board warping after copper embedding. The method includes: providing a first core board, which is a double-sided copper-clad laminate with pre-fabricated circuit patterns, used to provide intermediate copper layer support in the copper-embedded area to form a symmetrical multilayer structure including intermediate copper layer support, thereby dispersing internal stress and providing additional copper layer support; a first lamination: stacking a first copper foil, a first prepreg, the first core board, a second prepreg, and a second copper foil in sequence to form a first stacked structure, and laminating them to obtain a first lamination board; a second lamination: opening a window larger than the copper block in the first lamination board, placing the copper block into the window, and then stacking and laminating the first lamination board, a third prepreg, and a third copper foil after the copper block is placed in the window to form a second lamination board, followed by subsequent processing of the second lamination board. This invention can effectively suppress board warping.

Description

Technical Field

[0001] This invention relates to the field of printed circuit board manufacturing technology, specifically to a method for manufacturing a high-heat-dissipation, high-current-carrying integrated buried copper block circuit board and the circuit board obtained by the method, which is particularly suitable for automotive power control modules with high-density interconnect (HDI) structures that need to simultaneously meet the requirements of high current transmission, high heat dissipation and low board warpage. Background Technology

[0002] In some power control circuits of intelligent connected vehicles, there are situations involving large current transmission or instantaneous large current transmission, and there are many integrated circuits that are prone to heat generation. Therefore, it is necessary to meet the requirements of high heat dissipation and high current carrying capacity.

[0003] Existing technologies employ the method of embedding copper blocks in the circuit board to achieve high heat dissipation. Further refinement of the copper block design allows it to not only dissipate heat but also directly participate in conduction and high-current control. Simultaneously, high-density interconnect designs (blind vias, buried vias) further support simultaneous heat dissipation during integrated circuit soldering.

[0004] However, the following problems exist in the processing of high-density interconnect copper block circuit boards: First, if the embedded copper blocks are in an asymmetrical position in the overall board structure, board warping is likely to occur after combining with the high-density interconnect circuit design; Second, when soldering components in subsequent processes, the uneven heating of the board after reflow soldering further aggravates board warping.

[0005] Therefore, there is an urgent need to provide a method for manufacturing an integrated buried copper block circuit board that can systematically solve the above-mentioned board warping problem while taking into account both high heat dissipation and high current conduction. Summary of the Invention

[0006] This invention aims to solve the board warping problem caused by uneven internal stress resulting from the asymmetrical placement of embedded copper blocks within the board and the high-density interconnect lines, which exists in existing technologies. It provides a method for manufacturing a high-heat-dissipation, high-current-carrying integrated embedded copper block circuit board, and the circuit board produced by this method. By adding a first core board during the first lamination process, a symmetrical multilayer structure containing an intermediate copper layer is formed, dispersing internal stress and providing rigid support, effectively suppressing board warping.

[0007] In a first aspect, the present invention provides a method for manufacturing a high-heat-dissipation, high-current-carrying integrated buried copper block circuit board, comprising the following steps: A first core board is provided, which is a double-sided copper-clad board with a circuit pattern already fabricated. The first core board is used to provide intermediate copper layer support in the buried copper block area to form a symmetrical multilayer structure containing intermediate copper layer support, thereby dispersing internal stress and providing additional copper layer support. First lamination: The first copper foil, the first prepreg, the first core board, the second prepreg, and the second copper foil are stacked in sequence to form a first stacked structure, and then laminated to obtain the first laminated plate; Second pressing: A window larger than the copper block is opened on the first pressing plate. The copper block is placed in the window. Then, the first pressing plate, the third prepreg, and the third copper foil are stacked and pressed in sequence to form the second pressing plate. Then, the second pressing plate is processed in subsequent steps.

[0008] Furthermore, the method also includes: Third lamination: The second lamination plate, the fourth prepreg, and the fourth copper foil are stacked and laminated in sequence, and the laminated multilayer board is then processed in subsequent steps.

[0009] Furthermore, the method also includes: Before the second pressing, the first pressing plate and the third semi-cured sheet are baked at 120±5℃ for 2.0 to 5.5 hours.

[0010] Furthermore, The first prepreg, the insulating layer of the first core board, and the second prepreg are all made of materials with high Tg value and low Z-axis expansion coefficient. Their Tg value is 170℃ to 180℃, and their Z-axis Pre-Tg expansion coefficient is 40-50ppm / ℃. Both the third and fourth precured sheets are made of materials with medium Tg values ​​and low Z-axis expansion coefficients, with Tg values ​​ranging from 150°C to 170°C and Z-axis Pre-Tg expansion coefficients of 40-50 ppm / °C.

[0011] Furthermore, the method also includes: During the second and / or third pressing, a thick copper foil with a thickness ≥105μm is provided on one side of the copper-embedded block, and the thick copper foil is removed after pressing.

[0012] Furthermore, the thick copper foil has a non-continuous groove corresponding to the area covering the embedded copper block. The single-sided dimension of the non-continuous groove is larger than the size of the copper block, and the non-continuous groove is connected by a connecting bridge.

[0013] Furthermore, the second and third pressings both employ the following pressing temperature profiles: Heat to the maximum pressing temperature at a rate of 2.0-2.5℃ / min, hold at that temperature, and then cool down at a rate of 0.5-1.0℃ / min.

[0014] Furthermore, the second and third pressing processes both employ a stepped pressurization method: successively low pressure, medium pressure, and full pressure stages, with simultaneous depressurization during the cooling stage.

[0015] Furthermore, the pressing parameters for the second and third pressings are as follows: The initial pressure was 100 PSI / cm², gradually increased to 450 PSI / cm², and then gradually decreased to 0; the initial temperature was 140℃, increased to 210℃ and held, and then decreased to 140℃. The specific operating parameters for each stage include: The pressure changes were: 100→200→400→450→450→450→450→400→400→0 PSI / cm², with the time for each stage being 10min, 10min, 10min, 20min, 25min, 25min, 60min, 10min, 5min, and 2min respectively.

[0016] Secondly, the present invention provides a high heat dissipation and high current carrying capacity integrated buried copper block circuit board, which is manufactured by any of the above-described manufacturing methods.

[0017] The main beneficial effects of this technical solution are: The present invention discloses a method for manufacturing a high heat dissipation and high current carrying capacity integrated buried copper block circuit board and a circuit board obtained by the method. By adding a first core board (double-sided copper-clad board with pre-fabricated circuit pattern) in the first lamination, the traditional buried copper block area is transformed from an adhesive layer or single-layer support structure into a symmetrical multi-layer structure containing an intermediate copper layer support.

[0018] This approach offers the following advantages: First, the first core board is located between the first and second copper foils, with prepregs symmetrically laminated on both sides, forming a stable "copper foil-prepreg-core board-prepreg-copper foil" stacked system. The copper layer in the core board provides additional rigid support, effectively dispersing the internal stress generated during lamination and subsequent reflow soldering, preventing stress concentration around the copper block. Second, the symmetrical multilayer structure limits the non-uniform flow of the prepreg during lamination, reducing local shrinkage differences caused by uneven adhesive flow and structurally suppressing board warping. Furthermore, this solution requires no additional special equipment or complex processes; it can be achieved simply by optimizing the stacking sequence and introducing a conventional core board, offering excellent process compatibility and cost-effectiveness. The copper blocks are embedded in the circuit board in a high-density interconnection manner, directly connecting to integrated circuits or chips, providing conductivity and heat dissipation. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0020] Figure 1 This is a flowchart illustrating a method for manufacturing a high-heat-dissipation, high-current-carrying integrated buried copper block circuit board according to Embodiment 1 of the present invention. Figure 2 This is a schematic diagram of a typical lamination and stacking method for existing copper-embedded circuit boards. Figure 3 A schematic diagram of a circuit board structure completed using the existing method for fabricating copper-embedded circuit boards; Figure 4 This is a schematic diagram of a first-stage pressing and stacking structure provided in Embodiment 2 of the present invention; Figure 5 This is a schematic diagram of a stacked structure for a second and third pressing according to Embodiment 2 of the present invention; Figure 6 This is a schematic diagram of another stacked structure for the second and third pressing provided in Embodiment 2 of the present invention; Figure 7 This is a schematic diagram of a planar structure of a thick copper foil provided in Embodiment 2 of the present invention; Figure 8 This is a schematic diagram of the structure of a circuit board completed according to the manufacturing method of the high heat dissipation and high current carrying capacity integrated buried copper block circuit board provided in Embodiment 2 of the present invention.

[0021] Explanation of reference numerals: 10, Window panel; 11, First laminated structure; 12, Second laminated structure; 20, Second pressed stacked structure; 21, Second pressed stacked structure including copper foil; 30, Third pressed stacked structure; 31, Third pressed stacked structure including copper foil; 101, First copper foil; 102, First prepreg; 103, First core board; 104, Second prepreg; 105, Second copper foil; 106, Copper block; 201, Third prepreg; 202, Third copper foil; 301, Fourth prepreg; 302, Fourth copper foil; 40, Thick copper foil; 401, Connecting bridge.

[0022] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0023] 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 a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0024] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0025] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0026] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0027] This invention aims to provide an integrated embedded copper block circuit board and its manufacturing method to solve the warping problem caused by the lack of rigid support around the copper block and the concentration of internal stress in existing automotive current control modules. Specific objectives include: forming a symmetrical multilayer structure by adding a first core board to disperse internal stress and provide copper layer support; optimizing the lamination temperature, pressure curve, and material matching to further suppress warping; and ultimately obtaining a high-reliability circuit board with a warping degree ≤0.35% (or even ≤0.2%), meeting the requirements of high current transmission, high heat dissipation, and high-temperature impact during reflow soldering.

[0028] To better understand the above technical solution, a detailed explanation of the technical solution is provided below with reference to the accompanying drawings.

[0029] Example 1

[0030] Figure 1 This is a flowchart illustrating a method for fabricating a high-heat-dissipation, high-current-carrying integrated buried copper block circuit board according to Embodiment 1 of the present invention. Figure 1 As shown, it includes the following steps: Step S100: Provide a first core board, which is a double-sided copper-clad board with a fabricated circuit pattern. The first core board is used to provide intermediate copper layer support in the buried copper block area to form a symmetrical multi-layer structure containing intermediate copper layer support, thereby dispersing internal stress and providing additional copper layer support. Step S200: First pressing: The first copper foil, the first prepreg, the first core board, the second prepreg, and the second copper foil are stacked in sequence to form a first stacked structure, and then pressed to obtain the first pressed plate; Step S300: Second pressing: A window larger than the copper block is opened on the first pressing plate. The copper block is placed in the window. Then, the first pressing plate, the third prepreg, and the third copper foil are stacked and pressed in sequence to form the second pressing plate. Then, the second pressing plate is processed in subsequent steps.

[0031] The current manufacturing method for copper-embedded circuit boards in automotive current control modules is generally achieved through two lamination processes. This typically involves directly placing the copper block into a stack of prepreg and copper foil, or embedding the copper block after opening a window in a single-layer core board. For example... Figure 2 and Figure 3 As shown, Figure 2 This is a typical lamination method for existing copper-embedded circuit boards. The lamination structure is as follows: First lamination structure 11: windows are created on the core board. Then, the core board with embedded copper blocks, prepreg, and copper foil are laminated for the first time to create the inner layer circuit pattern. A second lamination structure 12 is then used for a second lamination. If blind or buried vias are required, they are created by laser drilling and full-board electroplating of the first and second lamination boards to form high-density interconnects. The completed circuit board structure is shown below. Figure 3 As shown. Because the copper block is only supported by a prepreg (adhesive layer) or core layer, and the copper block is in an asymmetrical position in the overall board structure, it is easy for board warping to occur due to the high-density interconnect circuit design. At the same time, the internal stress and asymmetry present during lamination can easily lead to further board warping due to uneven heating of the board during high-temperature impact.

[0032] To address this problem, the present invention provides a method for manufacturing a high-heat-dissipation, high-current-carrying integrated buried copper block circuit board, specifically including: Step S100: Provide the first core board.

[0033] A double-sided copper-clad laminate with a thickness of 0.25-1mm (e.g., a core board thickness of 0.5mm and an initial copper foil thickness of 35μm) is used. The inner layer circuit pattern is fabricated using conventional circuit fabrication processes (including punching holes, cleaning, film application, exposure, development, etching, and film removal) to form the first core board. This first core board provides intermediate copper layer support in the subsequent copper-buried area, forming a symmetrical multilayer structure containing at least two copper layers, thereby dispersing internal stress and providing additional copper layer support. The thickness of the copper-buried block is generally within 2mm, and the thickness of the first core board can be selected as 1 / 3 to 1 / 2 of the copper block thickness.

[0034] Step S200: Perform the first pressing.

[0035] Material preparation: First copper foil and second copper foil, the thickness of which should be selected according to actual needs, such as both being 35μm. First and second prepregs are high Tg halogen-free prepregs, and the first and second prepregs are of the same type, with an adhesive content of 40%-60%, preferably 50%.

[0036] Stacking: The first copper foil, the first prepreg, the first core board, the second prepreg, and the second copper foil are placed sequentially from bottom to top to form the first stacking structure.

[0037] Pressing: Using standard pressing parameters (such as temperature 200℃, pressure 350psi, time 90 minutes), the first pressed plate is obtained after pressing.

[0038] The original pressed structure was split into a multi-layer structure, and a first core board was added to disperse internal stress, provide more copper support layers, and reduce the impact of prepreg flow on warping.

[0039] Step S300: Perform the second pressing.

[0040] First, a window is milled on the first pressing plate at the position corresponding to the copper block. The window is 0.1mm larger on each side than the copper block.

[0041] Place the copper block: Place the copper block (e.g., a copper block with a size of 10mm×10mm×0.8mm and a brown surface treatment) into the window, ensuring that the gap between the copper block and the edge of the window is uniform.

[0042] Stacking: The first laminating plate after the copper block is placed, the third prepreg (e.g., 0.1mm thick), and the third copper foil (e.g., 35μm thick) are stacked sequentially. The third prepreg is preferably a prepreg with a medium Tg value and low expansion and contraction. The plates are laminated under slow heating and slow cooling conditions to obtain the second laminating plate, which is then processed in subsequent steps, such as: grinding the plate to remove excess adhesive around the copper block; laser drilling to drill blind holes (e.g., 0.1mm diameter); removing adhesive residue, copper plating, and full-board electroplating (including blind hole filling electroplating); fabricating outer layer circuitry (conventional pattern transfer and etching); punching target holes; and checking for board warping, etc.

[0043] If additional circuit layers are needed later, the board can be laminated and the layers added after the outer layer circuitry of the second lamination board is completed. If not, the solder mask pattern, surface treatment, and molding can be carried out after the outer layer circuitry of the second lamination board is completed to complete the circuit board fabrication.

[0044] In traditional processes, copper blocks are directly embedded in prepregs or single-layer core boards, lacking an intermediate copper layer for support. This embodiment adds a first core board, whose double-sided copper layers, along with the prepregs on both sides and the outer copper foil, form a symmetrical structure, significantly improving local rigidity and dispersing internal stress. Furthermore, the first and second prepregs use high Tg, while the third prepreg uses medium Tg; this combination of high and low Tg generates reverse compensating stress during heating, counteracting warping tendencies.

[0045] Furthermore, the method also includes: Third lamination: The second lamination plate, the fourth prepreg, and the fourth copper foil are stacked and laminated in sequence, and the laminated multilayer board is then processed in subsequent steps.

[0046] The third lamination, based on the second lamination (with embedded copper blocks and partial circuitry), adds further layers to achieve the multi-layered structure required for High-Density Interconnect (HDI). The specific steps are as follows: the second lamination board, the fourth prepreg, and the fourth copper foil are sequentially stacked and laminated. The lamination process utilizes an optimized temperature and pressure profile (slow heating and slow cooling) to cure the prepreg and bond the fourth copper foil to the surface of the second lamination board. Subsequent processing includes: laser drilling (drilling blind or buried vias), desmearing, copper plating, full-board electroplating (including blind via filling electroplating), surface circuitry fabrication, solder mask application, and surface treatment.

[0047] The fourth prepreg is the same as the third prepreg, using a medium Tg value, low Z-axis CTE, and medium adhesive content (40%-60%) to ensure thermal matching with medium Tg materials while avoiding excessive adhesive flow.

[0048] Preferably, pretreatment can be performed before pressing: the fourth semi-cured sheet and the second pressing plate are baked (120±5℃, 3-5.5 hours) to remove moisture.

[0049] The post-processing details are the same as existing technology processes, such as laser drilling: drilling blind holes (typically 0.1-0.15mm in diameter) to connect the fourth copper foil to the underlying inner layer circuitry. Resin removal: removing resin residue from the laser-drilled hole walls to ensure good subsequent copper plating. Copper plating: depositing a thin layer of copper (approximately 0.5-1μm) on the hole walls to make them conductive. Full-board electroplating: electroplating to thicken the copper layer inside the holes and fill the blind holes (blind hole filling electroplating), while simultaneously thickening the surface copper foil. Surface wiring: forming the final outer layer circuitry through pattern transfer and etching. Subsequent routine processes: solder mask, surface treatment (such as OSP, immersion gold), electrical testing, and visual inspection.

[0050] The third lamination adds outer layer circuitry and blind vias, supporting high-density component soldering and signal transmission, meeting the integration requirements of automotive current control modules. The medium-Tg material introduced in the third lamination is consistent with the underlying medium-Tg layer. During reflow soldering, they work synergistically with the high-Tg material (located in the first lamination layer) to continue providing reverse stress compensation, further balancing internal stress and ensuring that the final board warpage remains below 0.35%. The outer copper foil can be used to create wide circuitry, which, together with the inner copper blocks and buried vias, forms a low-impedance heat dissipation path, improving the module's current carrying capacity and heat dissipation performance.

[0051] Furthermore, the method also includes: Before the second pressing, the first pressing plate and the third semi-cured sheet are baked at 120±5℃ for 2.0 to 5.5 hours.

[0052] To ensure the core board and prepreg are fully dry before lamination, and to remove moisture from the board to prevent uneven expansion and contraction during lamination, which could lead to board warping, the boards can be baked. The first lamination board has already completed its first lamination and contains the first core board, prepreg, and copper foil. Care must be taken to avoid overheating during baking, which could cause the cured resin to age. The third prepreg: an uncured prepreg, sensitive to temperature and humidity.

[0053] Therefore, the selected baking conditions are: Temperature: 120±5℃ (i.e., 115-125℃). This temperature is lower than the curing start temperature of the prepreg (usually ≥130℃), which will not cause premature curing, but is sufficient to remove moisture. Time: 2.0-5.5 hours. The specific time depends on: the thickness and moisture absorption of the first lamination plate, the type and adhesive content of the prepreg, and the ambient humidity (the baking time needs to be extended in high humidity environments). The flowability of the third prepreg will decrease slightly after baking (some low molecular weight resin may volatilize), so the upper limit of the baking time needs to be controlled (it should not exceed 5.5 hours) to avoid affecting the filling capacity.

[0054] The baking equipment uses a nitrogen-filled oven or a vacuum oven to avoid high-temperature oxidation.

[0055] Prepreg should be laid flat or hung during baking to avoid uneven heating or sticking. After the first pressing, the prepreg should be opened and pressed a second time as soon as possible to prevent moisture absorption. If it cannot be used immediately, it should be stored in a drying cabinet (humidity ≤10%).

[0056] Baking the sheet metal removes moisture, preventing air bubbles and uneven expansion / contraction during lamination. The first lamination sheet may absorb ambient moisture during storage or previous processes. Without baking, the high temperature during lamination vaporizes the moisture, forming air bubbles between the prepreg and copper foil, or causing abnormal expansion in localized areas, leading to localized depressions or bulges in the sheet. Baking dries the sheet, ensuring stable lamination quality. It also improves the uniformity of prepreg flow. When prepreg absorbs moisture, the water in the resin reduces its high-temperature flowability and may cause inconsistent glue flow. Baking restores uniform resin flowability, ensuring sufficient glue filling during lamination and preventing stress concentration caused by insufficient glue or uneven glue flow. Baking also pre-releases residual stress within the first lamination sheet (thermal relaxation), reducing overall deformation during subsequent second lamination and reflow soldering. This, combined with material Tg matching and temperature-pressure curves, further controls warpage. Meanwhile, the dried board surface and the prepreg can form a tighter chemical bond during lamination, improving the peel strength between the copper foil and the prepreg, and between the copper block and the prepreg, thus avoiding delamination during subsequent processing.

[0057] Similarly, before the third pressing, the second pressing plate and the fourth prepreg can be baked under the same conditions.

[0058] Furthermore, The first prepreg, the insulating layer of the first core board, and the second prepreg are all made of materials with high Tg value and low Z-axis expansion coefficient. Their Tg value is 170℃ to 180℃, and their Z-axis Pre-Tg expansion coefficient is 40-50ppm / ℃. Both the third and fourth precured sheets are made of materials with medium Tg values ​​and low Z-axis expansion coefficients, with Tg values ​​ranging from 150°C to 170°C and Z-axis Pre-Tg expansion coefficients of 40-50 ppm / °C.

[0059] High Tg prepregs can be selected from commercially available high Tg halogen-free or standard FR-4 prepregs, such as Lianmao (IT-180A) and Shengyi (S1000-2M), with Tg=170~180℃ (DSC method) and Z-axis CTE≤50ppm / ℃ (below Tg).

[0060] For medium Tg prepregs, prepregs with Tg=150~170℃ can be selected, such as Shengyi (S1141) and Taiyao (TU-662), etc., and the Z-axis CTE should be controlled at 40-50ppm / ℃.

[0061] The insulation layer of the first core board: The insulating medium (FR-4) in the middle of the core board also needs to meet the requirements of high Tg and low Z-axis CTE, and is usually in the same system as the high Tg prepreg.

[0062] Storage and moisture protection: Both high Tg and medium Tg semi-cured sheets are hygroscopic and should be stored in a sealed environment with low humidity (≤10% RH). Before use, they should be treated according to the aforementioned baking conditions (120±5℃, 2-5.5h).

[0063] High-Tg prepreg is used for the first lamination (on the same side as the copper block), while medium-Tg prepreg is used for the second and third laminations (on the opposite side of the copper block). Although the two materials have different Tg values, their Z-axis CTE is similar (40-50 ppm / ℃), so the same temperature-pressure curve (slow heating, step-by-step pressurization) can be used, eliminating the need for frequent equipment adjustments.

[0064] High-Tg materials maintain high stiffness and low expansion at the high temperatures of reflow soldering, while medium-Tg materials experience significant expansion / contraction when crossing their Tg values. Because they are located on opposite sides of the copper block (the same side for high-Tg materials, the opposite side for medium-Tg materials), the expansion / contraction behavior of the medium-Tg prepreg differs from that of the high-Tg material. The combined internal stress generated by these two materials is exactly opposite to the warping direction of the current board, thus canceling each other out and achieving equilibrium.

[0065] Furthermore, the high Tg (≥170℃) ensures that the board retains sufficient rigidity at the peak lead-free soldering temperature (~260℃), preventing excessive softening that could lead to device displacement or solder joint cracking. The low Z-axis CTE (≤50ppm / ℃) reduces thermal mismatch between the via wall and the resin, improving the thermal cycle life of the vias.

[0066] With moderate adhesive content (40%-60%) and similar Z-axis CTE, the two materials exhibit consistent adhesive flow behavior during the pressing process. This prevents localized adhesive shortages or adhesive buildup due to excessive expansion differences, thereby reducing stress concentration points.

[0067] This embodiment requires specific Tg values ​​and Z-axis CTE ranges for a high-Tg material (used for the first lamination, on the same side as the copper block) and a medium-Tg material (used for the second / third lamination, on the opposite side of the copper block). This material combination utilizes the different expansion / contraction behaviors of the two materials during thermal cycling to generate reverse compensating stress, thereby effectively suppressing board warping while maintaining high heat resistance and process compatibility.

[0068] Furthermore, the method also includes: During the second and / or third pressing, a thick copper foil with a thickness ≥105μm is provided on one side of the copper-embedded block, and the thick copper foil is removed after pressing.

[0069] During the second or third lamination (or both), a thick copper foil is placed on the side where the copper block is located (i.e., the exposed side of the copper block), directly covering the surface of the first lamination plate (or the second lamination plate) with the window opened and the copper block placed inside. There is no prepreg between the thick copper foil and the underlying plate; they are in direct physical contact (or are separated only by an extremely thin release film for easy removal later).

[0070] The stacking order (taking the second pressing as an example, from top to bottom) is: thick copper foil, first pressing plate after the copper block is placed (copper block side facing up), third prepreg, and third copper foil; during pressing, the thick copper foil is located on the top layer and is in direct contact with the copper block and the plate surface.

[0071] Electrolytic copper foil or rolled copper foil with a thickness of ≥105μm is selected. The thick copper foil acts as a pressure buffer layer, dispersing the concentrated pressure applied by the press over a large area, preventing the edges of the copper block from being pressed into the board and causing local depressions or deformation of the copper block, thereby improving the flatness of the board surface. Moreover, it can accommodate the height difference between the copper block and the board surface, avoiding wrinkling during pressing. During the pressing process, the thick copper foil restricts the resin flow and shrinkage in the copper block area, reducing local internal stress caused by the curing shrinkage of the prepreg. Together with material Tg matching and temperature-pressure curves, it further reduces board warping.

[0072] Furthermore, the thick copper foil has a non-continuous groove corresponding to the area covering the embedded copper block. The single-sided dimension of the non-continuous groove is larger than the size of the copper block, and the non-continuous groove is connected by a connecting bridge.

[0073] Since there may be slight differences between the thickness of the copper block and the surface of the plate, the non-continuous groove allows the thick copper foil to deform locally to conform to the uneven surface, preventing the thick copper foil from wrinkling or breaking during pressing, while avoiding stress concentration caused by local overpressure.

[0074] For non-continuous through-slot prefabrication, the through-slot can be created on thick copper foil through etching or mechanical milling at positions corresponding to the copper block. Size requirements: The single-sided dimension (length, width, or diameter) of the through-slot is larger than the corresponding dimension of the copper block, typically 0.1~0.3mm larger per side, ensuring that the copper block does not make hard contact with the edge of the thick copper foil during pressing, leaving a gap. Connecting bridge design: The through-slot is not completely disconnected, retaining several connecting bridges (e.g., at the four corners or midpoints of the four sides) to keep the thick copper foil as a single piece. The width of the connecting bridge is generally 1~2mm, and the length is determined based on the distance from the slot edge. The number of connecting bridges depends on the size of the copper block and the thickness of the thick copper foil, typically four (at the four corners of a rectangular copper block) or more, to ensure overall strength and ease of operation.

[0075] When stacking, align the center of the slot with the center of the copper block so that the copper block is located inside the slot, avoiding the edge of the thick copper foil pressing on the copper block.

[0076] During the pressing process, the press pressure is transmitted through thick copper foil. There is no copper foil in the through groove area, and the copper block directly contacts the upper buffer material (or vacuum pressing film). The connecting bridge area bears the pressure transmission and allows for slight deformation.

[0077] The non-continuous through-slots maintain integrity, preventing the thick copper foil from splitting into multiple small pieces and facilitating automatic or manual picking, placement, and positioning. They also provide deformability: during lamination, if the copper block surface is slightly higher than the board surface, the connecting bridges can elastically bend or twist, allowing the thick copper foil to adapt to local height differences and avoiding wrinkles or localized overpressure. Furthermore, the connecting bridges restrict displacement, linking the independent parts together and preventing the thick copper foil from shifting during lamination.

[0078] After lamination, the thick copper foil can be directly peeled off the board surface due to the absence of prepreg bonding. The presence of connecting bridges allows the entire thick copper foil to be peeled off in one go, leaving no small pieces of copper residue. If there is slight adhesion at the connecting bridges, the residue can be removed by mechanical brushing or micro-etching without affecting the board surface quality.

[0079] If the thick copper foil has a complete, grooveless structure, the copper block will directly press against the thick copper foil during lamination, forming point-like high pressure, which may damage the surface of the copper block or cause local dents in the board. Non-continuous slots allow the corresponding areas of the copper block to be suspended, and the pressure is transmitted only through connecting bridges and the periphery, significantly reducing local pressure.

[0080] To enhance the adaptability of thick copper foil and prevent wrinkling, slight differences in copper thickness and board surface (manufacturing tolerances) can easily cause wrinkles during lamination of intact copper foil. Non-continuous slots divide the thick copper foil into multiple independently movable areas (connecting bridges act as hinges), allowing the thick copper foil to adapt to surface unevenness and maintain a flat and adhered surface.

[0081] Furthermore, the second and third pressings both employ the following pressing temperature profiles: Heat to the maximum pressing temperature at a rate of 2.0-2.5℃ / min, hold at that temperature, and then cool down at a rate of 0.5-1.0℃ / min.

[0082] The second and third pressings employed a pressing temperature profile with slow heating and slow cooling.

[0083] In the heating phase, the temperature is increased at 2.0-2.5℃ / min for approximately 28-35 minutes (from 140℃ to 210℃) to allow the prepreg to soften and flow evenly. In the heat preservation phase, the temperature is maintained at 210℃ for 25-30 minutes to allow the prepreg to fully cure and release stress. In the cooling phase, the temperature is increased at 0.5-1.0℃ / min for approximately 70-140 minutes (from 210℃ to room temperature) to allow for slow cooling and avoid the generation of internal stress from rapid cooling.

[0084] The pressure curve is linked to the temperature curve. Low pressure (100-200 PSI) is used in the initial stage of heating. After the resin flows, the pressure is gradually increased to full pressure (450 PSI). During the cooling stage, the pressure is gradually reduced.

[0085] This temperature setting is suitable for high and medium Tg prepregs (Tg 150-180℃), with a maximum temperature of 210℃, which is higher than the Tg of all materials, ensuring sufficient softening but not exceeding the material's decomposition temperature (typically >300℃).

[0086] A preferred pressing process is as follows: Place the stacked boards into the press and preheat to 140℃ (initial temperature).

[0087] The temperature was increased to 210°C at a rate of 2.0-2.5°C / min. During this period, the pressure was increased in steps from 100 PSI to 450 PSI.

[0088] Hold at 210℃ for 25-30 minutes, maintaining a total pressure of 450 PSI.

[0089] The temperature is reduced to below 140℃ at a rate of 0.5-1.0℃ / min. During this period, the pressure is gradually reduced to 0.

[0090] Remove the board and allow it to cool naturally to room temperature.

[0091] The bonding temperature profile in this embodiment effectively releases internal stress, preventing board warping. Slow heating allows the prepreg resin to gradually soften and flow, ensuring uniform filling of the area around the copper block and the gaps between circuit lines, thus avoiding localized stress concentration. Slow cooling allows sufficient time for the resin molecular chains to relax during the cooling process, reducing freezing stress. Compared to rapid cooling (>2℃ / min), warping can be reduced by more than 50%. It improves the uniformity of prepreg filling; rapid heating causes a sudden increase in resin fluidity, potentially causing the colloid to wash away from the copper block or circuit lines, or even overflow and form lumps. A gentle heating rate of 2.0-2.5℃ / min allows the resin to flow smoothly, resulting in more uniform filling and reducing voids and missing colloids. It improves the bonding strength between the copper block and the substrate; the insulation section (210℃) ensures complete resin curing (curing degree ≥95%), while simultaneously ensuring sufficient wetting of the copper block surface with the resin, improving peel strength. Slow cooling prevents microcracks at the copper block-resin interface due to excessive shrinkage.

[0092] It can also synergistically match the glass transition temperatures (Tg) of materials, enhancing the reverse stress compensation. This temperature curve ensures that high-Tg materials (Tg 170-180℃) and medium-Tg materials (Tg 150-170℃) successively cross their respective glass transition temperatures during the heating process, forming a sequential softening-solidification process, thereby producing the expected reverse stress compensation effect during the cooling stage. If the heating is too rapid, the transition times of the two materials overlap, and the compensation effect is weakened.

[0093] Furthermore, the second and third pressing processes both employ a stepped pressurization method: successively low pressure, medium pressure, and full pressure stages, with simultaneous depressurization during the cooling stage.

[0094] The low-pressure stage of lamination (100-200 PSI) corresponds to the initial stage of heating (140-160℃). The prepreg has not yet softened sufficiently. The low pressure prevents the resin from being squeezed out and at the same time removes the air between the layers.

[0095] The medium-voltage stage (200-400 PSI) corresponds to the temperature range (160-195℃) where the resin begins to flow. Medium-voltage promotes the uniform filling of the colloid around the copper block and the gaps in the circuit, avoiding voids.

[0096] During the full pressure stage (450 PSI), full pressure is applied during the holding period at the highest temperature (210°C) to ensure that the resin is fully cured and that the copper block is tightly bonded to the substrate.

[0097] During the cooling phase, the pressure is reduced simultaneously from 450 PSI to 0 to prevent the plate from rebounding or delaminating due to a sudden drop in pressure, while releasing internal stress.

[0098] Furthermore, the pressing parameters for the second and third pressings are as follows: The initial pressure was 100 PSI / cm², gradually increased to 450 PSI / cm², and then gradually decreased to 0; the initial temperature was 140℃, increased to 210℃ and held, and then decreased to 140℃. The specific operating parameters for each stage include: The pressure changes were: 100→200→400→450→450→450→450→400→400→0 PSI / cm², with the time for each stage being 10min, 10min, 10min, 20min, 25min, 25min, 60min, 10min, 5min, and 2min respectively.

[0099] To obtain the most suitable pressing parameters, this embodiment of the invention conducts experiments by selecting different pressing temperatures and pressure parameters. The experimental process is shown in Table 1 below, which verifies the pressing process.

[0100] Table 1: Experimental parameters for different pressing examples

[0101] Pressing temperature method ①: slow heating, rapid cooling; Pressing temperature method ②: rapid heating, slow cooling; Pressing temperature method ③: slow heating, slow cooling.

[0102] Comparison results: Pressing temperature method ③ is the best. Slow heating and slow cooling provide sufficient temperature and time conditions for the semi-cured sheet to flow, ensuring that the adhesive flows fully and stress is fully released. This avoids the formation of microscopic particulate adhesive that does not flow sufficiently, which could lead to insufficient stress release and inadequate filling.

[0103] Compression pressure: A slow heating phase is used in conjunction with a slow pressure increase from low to medium. After reaching the maximum compression temperature, the pressure gradually decreases from low to medium. After a period of medium-pressure compression, the pressure is increased to high. After compression, the pressure is simultaneously reduced slowly during a slow cooling phase. This stepped pressurization method, consisting of a segmented pseudo-compression process of low pressure → medium pressure → full pressure, can match the compression temperature, ensuring that the colloid reaches the necessary flow temperature and pressure conditions, achieving full flow before full-pressure filling. The final compression temperature, time, and pressure parameters are shown in Table 2 below.

[0104] Table 2: Compaction Temperature, Time, and Pressure Parameters

[0105] The pressing parameters of this invention prevent excessive resin loss: low-pressure start-up avoids the prepreg being crushed by high pressure before softening, resulting in excessive resin overflow and incomplete filling. Uniform filling without voids: the medium-pressure stage ensures smooth resin flow, filling the tiny gaps between the copper block and the window while expelling air bubbles. Reduced internal stress: full-pressure holding for a sufficient time (60 min) allows for full resin cross-linking, followed by slow pressure reduction to avoid residual stress caused by sudden pressure changes during cooling. Reduced board warpage: stepped pressurization combined with slow cooling ensures uniform shrinkage across all layers of the board, controlling warpage to below 0.35%. Improved copper block bonding strength: the full-pressure stage ensures tight contact between the copper block and the prepreg, increasing peel strength by over 30%.

[0106] This invention transforms the traditional single-layer adhesive or single-layer support structure of embedded copper circuit boards into a symmetrical multi-layer stacked structure including a first core board. The first core board, along with its two sides of copper foil and prepreg, forms a stable stress dispersion system, significantly improving the rigidity of the embedded copper area and effectively suppressing internal stress concentration during lamination and subsequent reflow soldering. Simultaneously, by selecting high-Tg (170-180℃) and low-Z-axis coefficient of thermal expansion prepreg and core board insulation layer in the first lamination, and medium-Tg (150-170℃) and similarly low-Z-axis coefficient of thermal expansion prepreg in the second and third laminations, the high-Tg material maintains high rigidity at high temperatures, while the medium-Tg material maintains high rigidity during hot stamping. The material exhibits significant expansion upon impact, creating internal stress compensation within the board that opposes the warping direction of existing technologies. This stress restraint balance significantly reduces warping. Furthermore, the use of a slow heating and cooling temperature-pressure curve and a stepped pressurization process ensures full flow of the prepreg and complete stress release. A thick copper foil with a non-continuous groove is placed on the copper block side as a temporary pressure buffer layer to prevent damage to the copper block and adapt to surface unevenness, further improving the flatness of the lamination. The entire solution requires no special equipment, has good process compatibility, and the resulting copper-embedded circuit board simultaneously meets the high reliability requirements of high current transmission, high heat dissipation, and lead-free reflow soldering, making it particularly suitable for harsh environments such as automotive current control modules.

[0107] Example 2

[0108] Embodiment 2 of the present invention provides a method for manufacturing a high heat dissipation, high current carrying capacity buried copper block circuit board, including the following steps.

[0109] The first pressing process includes: (1) Making the first core board: Take a double-sided copper-clad board and make the circuit pattern (including the process of making punching (target hole), cleaning, etc.).

[0110] (2) Pressing, please refer to Figure 4 , Figure 4 In this embodiment, the first pressing and stacking structure consists of the first copper foil 101, the first prepreg 102, the first core board 103, the second prepreg 104, and the second copper foil 105 stacked in sequence (forming the first stacking structure), and then pressed together to form the first pressing plate.

[0111] Optionally, before stacking, the first prepreg, the first core board, and the second prepreg are baked with the following parameters: 120±5℃ for 3.0 to 5.5 hours (purpose: to fully dry, remove moisture from the board, and prevent uneven expansion and contraction caused by moisture during pressing, thus causing board warping).

[0112] Optionally, the first prepreg, the insulating layer of the first core board, and the second prepreg all use materials with high Tg values ​​and low coefficient of thermal expansion (CTE) (preferably, the Tg value is 170~180℃, and the Z-axis Pre-Tg coefficient of thermal expansion is 40-50ppm / ℃).

[0113] The first and second prepregs have the same model number.

[0114] By breaking down the original press-fit structure into a multi-layer structure and adding a first core board, the internal stress is dispersed, more copper support layers are provided, and the impact of prepreg flow on warping is reduced.

[0115] The second pressing process includes: A window is made in the first pressing structure (the size of the window matches the size of the copper block, and one side is larger than the size of the copper block) to form a windowed plate. Perform stacking and pressing, such as Figure 5 As shown, the copper block 106, the windowed plate 10, the third prepreg 201, and the third copper foil 202 are stacked sequentially (forming the second pressing stacked structure 20), pressed together (the first inspection after pressing checks for board warping to ensure ≤0.2%), and then processed in subsequent steps, such as grinding (grinding away excess adhesive around the copper block), laser drilling (blind holes), removing adhesive residue, copper plating, and electroplating the entire board (including electroplating to fill blind holes). Afterward, circuitry is fabricated, and holes are punched again (target holes). This forms the second pressed board (not shown in the diagram).

[0116] Optionally, the window panel and the third semi-cured sheet are baked at 120±5℃ for 3.0 to 5.5 hours (purpose: to fully dry the sheet, remove moisture from the sheet, and prevent uneven expansion and contraction caused by moisture during pressing, which could lead to board warping).

[0117] To obtain the most suitable pressing parameters, this embodiment of the invention conducts experiments by selecting different pressing temperatures and pressure parameters. The experimental process is shown in Table 1 below, which verifies the pressing process.

[0118] Table 1: Experimental parameters for different pressing examples

[0119] Pressing temperature method ①: slow heating, rapid cooling; Pressing temperature method ②: rapid heating, slow cooling; Pressing temperature method ③: slow heating, slow cooling.

[0120] Comparison results: Pressing temperature method ③ is the best. Slow heating and slow cooling provide sufficient temperature and time conditions for the semi-cured sheet to flow, ensuring that the adhesive flows fully and stress is fully released. This avoids the formation of microscopic particulate adhesive that does not flow sufficiently, which could lead to insufficient stress release and inadequate filling.

[0121] Compression pressure: A slow heating phase is used in conjunction with a slow pressure increase from low to medium. After reaching the maximum compression temperature, the pressure gradually decreases from low to medium. After a period of medium-pressure compression, the pressure is increased to high. After compression, the pressure is simultaneously reduced slowly during a slow cooling phase. This stepped pressurization method, consisting of a segmented pseudo-compression process of low pressure → medium pressure → full pressure, can match the compression temperature, ensuring that the colloid reaches the necessary flow temperature and pressure conditions, achieving full flow before full-pressure filling. The final compression temperature, time, and pressure parameters are shown in Table 2 below.

[0122] Table 2: Compaction Temperature, Time, and Pressure Parameters

[0123] Optionally, the third prepreg uses a prepreg with a low Tg value (preferably, the Tg value is 150~170℃ and the Z-axis Pre-Tg expansion coefficient is 40-50ppm / ℃).

[0124] The third pressing process includes: like Figure 5 As shown, the second pressing plate (obtained by pressing the copper block 106, the window plate 10, the third prepreg 201, and the third copper foil 202) is stacked in sequence (forming the third pressing stack structure 30) and then pressed together.

[0125] Then, laser drilling, removal of adhesive residue, copper plating, and full-board electroplating (including blind via filling electroplating) are performed, followed by surface circuitry fabrication.

[0126] Optionally, the first, second, third, and fourth precured sheets are all precured sheets with a medium adhesive content (optionally, the adhesive content is 40% to 60%).

[0127] While ensuring the thickness and sufficiency of the filler, using a medium-content prepreg has more stable performance than a high-content prepreg, avoiding problems such as excessive glue overflow after lamination, uneven circuit patterns, and other issues caused by excessive glue flow in high-content prepregs, which affect the flatness of the board.

[0128] The first prepreg, the insulating layer of the first core board, and the second prepreg all use materials with high Tg values ​​and low coefficient of thermal expansion (CTE) (preferably, the Tg value is 170°C to 180°C, and the Z-axis Pre-Tg coefficient of thermal expansion is 40-50ppm / °C).

[0129] In addition, the third and fourth prepregs have Tg values ​​and low expansion and contraction values ​​(preferably, the Tg value is 150~170℃ and the Z-axis Pre-Tg expansion and contraction coefficient is 40-50ppm / ℃).

[0130] The two are matched: the first and second semi-cured sheets use high Tg values, while the third and fourth semi-cured sheets use medium Tg values. After forming the overall board, the Tg matching of different materials with low coefficients of expansion and contraction creates internal stress compensation in the opposite direction to the "warping direction of existing technology", forming a restraining balance effect of internal stress and reducing board warping problems.

[0131] Optionally, such as Figure 6 As shown, during the second and third pressing, a thick copper foil 40 is placed on one side of the copper block to form a second pressing stack structure 21 containing copper foil and a third pressing stack structure 31 containing copper foil.

[0132] Optionally, the thickness of the thick copper foil is ≥105μm. Function: To add a thick copper layer as a balancing layer on the opposite side of the circuit layer addition, in order to counteract the stress caused by the layer addition.

[0133] Optionally, such as Figure 7 As shown, Figure 7 This is a schematic diagram of the planar structure of a thick copper foil. In the area where the thick copper foil covers the embedded copper block, there are non-continuous slots. The size of one side of the non-continuous slot is larger than that of the copper block.

[0134] Non-continuous through slots are connected by connecting bridges 401, which are copper foils that were not etched through (or milled through) during the fabrication of the through slots.

[0135] After lamination, the thick copper foil is removed, and subsequent processing steps (which may include: full-board electroplating, surface circuit patterning, solder masking, surface treatment, electrical testing, and visual inspection) are performed to form the final circuit board, with the structure as follows: Figure 8 As shown.

[0136] Significantly reduced board warpage: Through the combined effect of the above structure, materials and processes, the warpage of the circuit board is reduced from more than 2.5% in the existing technology to less than 0.35%, and can even be controlled within 0.2%, which fully meets the stringent flatness requirements of automotive current control modules.

[0137] This invention optimizes the stacked structure by changing the traditional lamination method. The original single-layer adhesive layer or single-core board structure is split into a symmetrical multi-layer stacked structure including a first core board. The added first core board provides additional copper layer support, effectively dispersing internal stress and reducing the impact of uneven prepreg flow on warping. It also improves the local rigidity of the copper-embedded area. The first lamination uses a high Tg (170-180℃) prepreg and core board insulation layer with a low Z-axis coefficient of thermal expansion (40-50ppm / ℃). The second and third laminations use a medium Tg (150-170℃) prepreg with the same low Z-axis coefficient of thermal expansion. The high Tg material maintains rigidity and restricts expansion on the same side as the copper block, while the medium Tg material softens first and expands significantly on the opposite side. The two materials create a torque that causes the copper block surface to concave, thus counteracting the tendency of the copper block surface to bulge in the prior art. This creates internal stress compensation in opposite directions, achieving stress restraint balance and suppressing warping from the material source. A temperature curve is employed, involving a slow heating (2.0-2.5℃ / min) to 210℃, holding at that temperature, and then a slow cooling (0.5-1.0℃ / min), combined with a stepped pressurization method (low pressure → medium pressure → full pressure → gradual depressurization, pressure gradually increasing from 100 PSI / cm² to 450 PSI / cm² and then decreasing to 0). This process ensures sufficient flow of the prepreg, uniform filling, and complete stress release, avoiding residual stress caused by rapid heating and cooling and sudden pressure changes. Overall synergistic effects: the stacked structure, material selection, and lamination process are interconnected and mutually influential. The spatial distribution of the first core board and high / low Tg materials provides a structural basis for stress compensation; the optimized temperature-pressure curve ensures the full utilization of material properties; and the thick copper foil temporary balancing layer further improves lamination flatness. The synergistic effect of these features systematically solves the board warping problem from three levels: internal stress dispersion, reverse compensation, and process release, while also meeting the reliability requirements of high current transmission, high heat dissipation, and lead-free reflow soldering. Furthermore, it has good process compatibility and is suitable for mass production.

[0138] Example 3

[0139] Embodiment 3 of the present invention also provides a high heat dissipation and high current carrying capacity buried copper block circuit board, which is manufactured by the high heat dissipation and high current carrying capacity buried copper block circuit board manufacturing method described in any of the above embodiments.

[0140] The high heat dissipation and high current carrying capacity buried copper circuit board of the present invention is manufactured by the high heat dissipation and high current carrying capacity buried copper circuit board manufacturing method in method embodiment one or two, so the description is relatively simple. For details, please refer to the relevant descriptions in the previous method embodiments, which will not be repeated here.

[0141] It should be noted that, due to the high precision of circuit board processing, the high density of circuit distribution, and the thinness of the stack-up structure, all reaching the micron level, it is difficult to represent certain layers or certain patterns if the actual stack-up structure is drawn. Therefore, the accompanying drawings in this embodiment are graphic representations that highlight the technical features and do not represent the actual circuit board structure in the processing process, nor do they represent scaled-up views of the processing structure.

[0142] This embodiment adopts a description method based on technical features as key nodes, and the existing technology in the processing process may not be described in detail. For example, the existing technology for circuit pattern making generally assumes "dry film application → exposure → development → etching → film removal", and the basic process of lamination generally assumes "core board layer extraction → prepreg extraction → stacking → fusion / riveting → layout → lamination → X-ray targeting → burr removal". Therefore, the understanding of this embodiment is mainly the understanding of the process of forming technical features during processing.

[0143] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made under the inventive concept of the present invention using the description and drawings of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for manufacturing a high-heat-dissipation, high-current-carrying integrated buried copper block circuit board, characterized in that, Includes the following steps: A first core board is provided, which is a double-sided copper-clad board with a circuit pattern already fabricated. The first core board is used to provide intermediate copper layer support in the buried copper block area to form a symmetrical multilayer structure containing intermediate copper layer support, thereby dispersing internal stress and providing additional copper layer support. First lamination: The first copper foil, the first prepreg, the first core board, the second prepreg, and the second copper foil are stacked in sequence to form a first stacked structure, and then laminated to obtain the first laminated plate; Second pressing: A window larger than the copper block is opened on the first pressing plate. The copper block is placed in the window. Then, the first pressing plate, the third prepreg, and the third copper foil are stacked and pressed in sequence to form the second pressing plate. Then, the second pressing plate is processed in subsequent steps.

2. The manufacturing method according to claim 1, characterized in that, The method further includes: Third lamination: The second lamination plate, the fourth prepreg, and the fourth copper foil are stacked and laminated in sequence, and the laminated multilayer board is then processed in subsequent steps.

3. The manufacturing method according to claim 1, characterized in that, The method further includes: Before the second pressing, the first pressing plate and the third semi-cured sheet are baked at 120±5℃ for 2.0 to 5.5 hours.

4. The manufacturing method according to claim 2, characterized in that, The first prepreg, the insulating layer of the first core board, and the second prepreg are all made of materials with high Tg value and low Z-axis expansion coefficient. Their Tg value is 170℃ to 180℃, and their Z-axis Pre-Tg expansion coefficient is 40-50ppm / ℃. Both the third and fourth precured sheets are made of materials with medium Tg values ​​and low Z-axis expansion coefficients, with Tg values ​​ranging from 150°C to 170°C and Z-axis Pre-Tg expansion coefficients of 40-50 ppm / °C.

5. The manufacturing method according to claim 2, characterized in that, The method further includes: During the second and / or third pressing, a thick copper foil with a thickness ≥105μm is provided on one side of the copper-embedded block, and the thick copper foil is removed after pressing.

6. The manufacturing method according to claim 5, characterized in that, The thick copper foil has a non-continuous groove corresponding to the area covering the embedded copper block. The single-sided dimension of the non-continuous groove is larger than the size of the copper block, and the non-continuous groove is connected by a connecting bridge.

7. The manufacturing method according to claim 1, characterized in that, The second and third pressing processes both use the following pressing temperature profiles: Heat to the maximum pressing temperature at a rate of 2.0-2.5℃ / min, hold at that temperature, and then cool down at a rate of 0.5-1.0℃ / min.

8. The manufacturing method according to claim 7, characterized in that, The second and third pressing processes both employ a stepped pressurization method: successively low pressure, medium pressure, and full pressure stages, with simultaneous depressurization during the cooling stage.

9. The manufacturing method according to claim 8, characterized in that, The pressing parameters for the second and third pressing are as follows: The initial pressure was 100 PSI / cm², gradually increased to 450 PSI / cm², and then gradually decreased to 0; the initial temperature was 140℃, increased to 210℃ and held, and then decreased to 140℃. The specific operating parameters for each stage include: The pressure changes were: 100→200→400→450→450→450→450→400→400→0 PSI / cm², with the time for each stage being 10min, 10min, 10min, 20min, 25min, 25min, 60min, 10min, 5min, and 2min respectively.

10. A high-heat-dissipation, high-current-carrying integrated buried copper block circuit board, characterized in that, It is manufactured by the manufacturing method according to any one of claims 1 to 9.

Images