Embedded IC printed circuit board and method of manufacturing the same

Abstract

The application provides an embedded IC printed circuit board and a preparation method thereof. The method comprises the following steps: pre-treating a copper block substrate; milling an embedded groove on a copper-clad substrate etched with an inner layer pattern, and forming an adaptive substrate through cleaning, brown oxidation and solidification; processing an asymmetric groove body on a PP plate stack; embedding a pre-packaged copper block into a substrate groove position, stacking a PP plate with an asymmetric stress groove, and laminating with a copper foil and a dummy plate; after implementing hole wall metallization, dynamically adjusting electroplating parameters based on real-time copper thickness feedback; canceling a side strip clamp and monitoring current in real time, and implementing hole area selective copper plating; using a dummy plate as a first piece to calibrate etching parameters, and precisely controlling line width tolerance; and sequentially performing solder mask patterning, electrical testing, profile milling, selective tin plating, mechanical bending and cleaning and packaging to obtain the embedded IC printed circuit board. Through the copper block pre-packaging treatment and the asymmetric stress groove cooperative design, the application solves the problem of thermal expansion delamination of the heterogeneous material interface.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of circuit board manufacturing, and particularly relates to an embedded IC printed circuit board and a preparation method thereof. BACKGROUND

[0002] With the rapid development of electronic devices towards higher performance, smaller size and higher integration, unprecedented requirements are put forward for the bearing capacity, heat dissipation efficiency and structural complexity of printed circuit boards (PCB). Embedded design, especially embedding thick copper blocks or copper substrates with excellent electrical and thermal conductivity directly into the PCB laminated structure, has become a key technical path to meet the needs of large current bearing and high efficiency heat dissipation.

[0003] However, realizing such a highly integrated embedded copper substrate structure faces a series of severe and interrelated technical bottlenecks in the existing manufacturing process, which restricts the reliability and yield of the product.

[0004] The first difficulty lies in the precise embedding and interface treatment of heterogeneous materials. The traditional PCB lamination process is mainly aimed at uniform copper-clad plates and prepregs, while embedding independent thick copper blocks with significantly larger volume and thickness into the core layer will introduce serious material physical property difference problems. Under the high temperature and high pressure environment of lamination, due to the large difference in coefficient of thermal expansion (CTE) between the copper block and the surrounding resin matrix (such as PP), interface separation, voids or local stress concentration are extremely easy to occur. This not only weakens the mechanical integrity of the structure, but also becomes a source of failure in subsequent thermal cycling or working process. The existing process lacks the ability to control the reliable combination of such heterogeneous material interfaces, especially how to ensure seamless filling and firm bonding of the copper block edge and the matrix, preventing delamination or micro-cracks, which is a core challenge that needs to be broken through.

[0005] Secondly, the complex geometric structure puts forward strict requirements on the filling and forming process. Special hole structures such as "gourd holes" are often designed between embedded copper blocks or specific functional areas to achieve specific electrical connection or mechanical support purposes. Such holes usually have the characteristics of narrowness, large depth-width ratio or irregular shape. Under the existing technical conditions, it is extremely difficult to uniformly and without voids fill the insulating or structural resin gel into these complex cavities. The shrinkage, insufficient flow or air entrapment of the filling material during the curing process can easily lead to problems such as hole voids, incomplete filling or poor combination with the hole wall. These defects can seriously affect the mechanical strength, electrical insulation performance and long-term reliability of the hole structure, becoming a potential failure hazard.

[0006] Third, the multiple and differentiated plating requirements bring significant process conflicts and control problems. On the one hand, in order to ensure the reliability of electrical interconnection, especially for the key hole (such as via) carrying current, the copper layer in the hole needs to reach a sufficient thickness. On the other hand, in order to meet the etching accuracy of fine lines and signal integrity, the copper thickness on the board surface also needs to be strictly controlled in a relatively thin and extremely narrow tolerance range. This forms an irreconcilable contradiction in the traditional panel plating combined with pattern plating process. The whole board plating improves the overall copper thickness, which is beneficial to ensure the hole copper, but inevitably leads to excessive thickness of the surface copper and is difficult to accurately control to the target thin copper range; while simply relying on pattern plating to thicken the hole copper, it puts forward extreme requirements for mask precision, plating solution dispersion ability and current distribution uniformity, and it is easy to have problems of insufficient hole copper or accidental thickening of surface copper beyond the tolerance. SUMMARY

[0007] In view of the above situation, the main purpose of the present application is to provide an embedded IC printed circuit board and a preparation method thereof to solve the above technical problems.

[0008] The present application provides a preparation method of an embedded IC printed circuit board, which comprises the following steps:

[0009] Step 1, the copper block substrate is covered with adhesive tape by a special jig, and a sealed copper block substrate with bubble elimination is formed by exhaust through a film press. The sealed copper block substrate with bubble elimination is subjected to brown oxidation treatment to form a brown copper block substrate. The brown copper block substrate is baked and cured to obtain a pre-cured copper block substrate.

[0010] Step 2, the copper-clad substrate is cut and the process edge is designed to form a process edge substrate. The process edge substrate is etched to form an inner layer pattern substrate. The inner layer pattern substrate is milled to form a substrate with copper block grooves. The substrate with copper block grooves is cleaned to obtain a clean groove body substrate. The clean groove body substrate is subjected to brown oxidation and baking and curing to obtain a cured groove body substrate.

[0011] Step 3, the PP plate material is stacked and cut to form a to-be-processed PP plate. An asymmetric groove body is machined on the to-be-processed PP plate using a high-frequency milling cutter to obtain a PP plate with an asymmetric stress groove.

[0012] Step 4, the pre-cured copper block substrate is embedded into the groove position of the cured groove body substrate, the PP plate with asymmetric stress groove and the copper foil are stacked, and the false plate is pressed to form a thick copper embedded laminated plate. The thick copper embedded laminated plate is subjected to X-ray alignment detection to obtain a qualified laminated plate. Through holes are machined on the qualified laminated plate to form a hole-containing substrate.

[0013] Step 5, the hole substrate is placed in the pulsed magnetic field generator to apply an axial magnetic field and an alternating electric field, so that the residual metal particles in the hole are arranged along the magnetic force line, and the epoxy-polyimide composite colloid containing carboxylated carbon nanotubes is injected into the hole, the carbon nanotubes are arranged along the hole axis under the action of the magnetic field, and the alternating electric field induces the colloid to generate microfluidic oscillation, and the bubbles in the hole are removed, and the epoxy-polyimide composite colloid is cured in stages to obtain a functionalized filled substrate;

[0014] Step 6, chemical copper plating is performed on the functionalized filled substrate to form a hole metallized substrate; the surface copper thickness of the hole metallized substrate is measured and the electroplating parameters are adjusted, and after electroplating, a surface copper standard substrate is obtained; pattern transfer is performed on the surface copper standard substrate to obtain an outer layer pattern substrate; the edge strip clamp is removed and the current is monitored in real time, and the outer layer pattern substrate is subjected to hole area selective copper plating to form a hole copper reinforced substrate;

[0015] Step 7, inner layer pattern transfer is performed on the hole copper reinforced substrate to obtain an inner layer pattern substrate; the etching parameters are calibrated with a dummy board as the first piece, and the inner layer pattern substrate is etched to form a high-precision circuit substrate;

[0016] Step 8, solder resist ink is printed on the high-precision circuit substrate and is patterned to obtain a solder resist cured plate; the solder resist cured plate is subjected to electrical testing, profile numerical control milling, chemical tin plating and mechanical bending, and finally cleaned and packaged to obtain an embedded IC printed circuit board.

[0017] Compared with the prior art, the beneficial effects of the present application are as follows:

[0018] 1、The present application solves the problem of thermal expansion delamination of heterogeneous material interface by copper block pre-packaging treatment and asymmetric stress groove design; in view of the risk of interface separation caused by the mismatch of thermal expansion coefficients of embedded copper block and resin substrate, a special fixture is used to exclude bubbles and seal with adhesive tape, and a gradient curing process is used to build a micro-rough interface with high bonding strength on the surface of the copper block; the asymmetric stress release groove of the PP plate is designed as electric area > bending area > non-electric area, so that the resin flows during lamination to form a self-adaptive stress buffer zone, which not only eliminates the micro-cracks and void defects at the edge of the copper block, but also realizes the molecular-level fusion of heterogeneous materials under high temperature and high pressure, greatly improving the long-term reliability of the structure under extreme temperature cycling.

[0019] 2、The application solves the challenge of dense filling and functional integration of high-depth-diameter-ratio special-shaped holes through the cooperation of electromagnetic field and microfluidic filling technology; innovatively uses axial magnetic field to drive metal particles and functionalized nanotubes to directionally self-assemble along the hole, to build a longitudinal high-conducting path; simultaneously applies an alternating electric field to induce micro-scale oscillatory flow of colloids, to remove bubbles in the hole and ensure the filling density, so that a three-dimensional network structure with excellent electric and thermal conductivity is formed inside the special-shaped hole, which breaks through the bottleneck of air voids and poor interface bonding in traditional filling process, and provides an ultra-low impedance current channel and a high-efficiency heat management path for a high-power embedded IC.

[0020] 3、The application breaks through the process compatibility of high-aspect-ratio micro-hole copper plating and ultra-thin surface copper through the dynamic control strategy of hole surface cooperated with copper plating; establishes a surface copper thickness real-time feedback mechanism to dynamically optimize the electroplating parameters, simultaneously cancels the edge clamps and implements hole area selective copper plating, so that the electroplating current is accurately focused on the deep hole area; this strategy enables the copper layer on the hole wall to be directionally reinforced and deposited, while strictly inhibiting the thickening of the surface copper in the non-target area, breaking the deadlock of traditional electroplating process that "preserving hole copper loses surface copper, and controlling surface copper damages hole copper", and realizing the coordinated leap of micro-hole conductivity and ultra-fine line etching precision.

[0021] 4、The application achieves the limit integration of precise lines and complex three-dimensional structures through etching intelligent calibration and three-dimensional forming process chain; an etching window is locked by introducing a false board first piece calibration system in the etching link, so that the key line width tolerance reaches micron-level precision; combined with the cooperative control of solder mask patterning and mechanical bending, a high-precision three-dimensional wiring network is built on the ultra-thin substrate, which solves the spatial layout contradiction of embedded IC, and at the same time makes the product maintain signal purity and structural stability in a harsh electromagnetic environment, to provide a better integrated solution for high-density electronic systems.

[0022] Additional aspects and advantages of the application will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or can be learned by practice of the application. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a preparation flow chart of the segmented, leadless gold finger plate of the application. DETAILED DESCRIPTION

[0024] Embodiments of the application are described in detail below with reference to the attached drawings, in which the same or similar elements are denoted by the same or similar reference signs throughout. The embodiments described below with reference to the drawings are exemplary and are only used to explain the application, and cannot be understood as a limitation of the application.

[0025] These and other aspects of embodiments of the present application will become clear from the following description and the accompanying drawings. In the description and drawings, particular embodiments of the application are disclosed in detail, which represent some ways of implementing the principles of the application, but it should be understood that the scope of the embodiments of the present application is not limited thereto.

[0026] Embodiment 1

[0027] Please refer to Figure 1 , Figure 1 The flow chart of the preferred embodiment of the preparation method of the embedded IC printed circuit board of the present application is shown in the figure, and specifically comprises the following steps:

[0028] Step 1, take a copper block substrate, cover it with a high-temperature-resistant polyimide adhesive tape through a special fixture, ensure that the position accuracy of the adhesive tape is ≤0.1mm, and use a film press to eliminate bubbles at a pressure of 0.5MPa to form a bubble-eliminated sealed copper block substrate; use Atotech Bondfilm solution to perform brown oxidation treatment on the bubble-eliminated sealed copper block substrate to form a brown copper block substrate; and bake the brown copper block substrate at 180℃ for 60min to obtain a pre-cured copper block substrate.

[0029] Step 2, cut an FR-4 copper-clad substrate, design the width of the process edge to be 30mm to form a process edge substrate; use acidic copper chloride etching solution to process the inner layer pattern of the process edge substrate to form an inner layer pattern substrate; mill an embedded slot on the inner layer pattern substrate, with the slot width being 3mil larger than the single side of the copper block, to form a substrate with a copper block slot; clean the substrate with a copper block slot to remove debris to form a clean slot body substrate; and after performing brown oxidation treatment on the clean slot body substrate, solidify it at 150℃ for 40min to obtain a solidified slot body substrate.

[0030] Step 3, stack and cut 6 pieces of 1080 type PP semi-cured sheet with a resin content of 68% to form a to-be-processed PP plate; use a high-frequency milling cutter with a rotation speed of 45000rpm to process an asymmetric slot body on the to-be-processed PP plate, with the slot width of the electrical connection area = the bending area + 4mil, and the slot width of the non-electrical area = the bending area + 5mm, and the slot depth being 65% of the thickness of the PP plate, to form a PP plate with an asymmetric stress slot.

[0031] Step 4, embed the pre-cured copper block substrate into the slot position of the solidified slot body substrate, stack the PP plate with an asymmetric stress slot and the MOZ type copper foil, use 3 pieces of 1080 type PP on each side of the PP plate, and press the false plate at a pressure of 350psi and a temperature of 185℃ for 90min to form a thick copper embedded laminated board; perform X-ray alignment detection on the thick copper embedded laminated board, with a deviation of ≤25μm, to obtain a qualified laminated board; laser drill holes on the qualified laminated board, with a hole diameter of 0.15mm, to form a hole-containing substrate.

[0032] Step 5, place the hole substrate into the electromagnetic field generator, set the axial magnetic field strength to 1.0T, the alternating electric field to 15kHz / 50V / cm, and inject the epoxy-polyimide colloid containing carboxylated carbon nanotubes with a concentration of 0.3wt% and a viscosity of 350cp into the hole. First, pre-cure at 80℃ / 30min to gel the colloid and fix the nanotube array, and then post-cure at 180℃ / 60min to form the functionalized filled substrate.

[0033] Step 6, chemically deposit copper on the functionalized filled substrate to form a hole metallized substrate; measure the surface copper thickness of the hole metallized substrate, which is 38μm. After adjusting the electroplating parameters, the surface copper thickness is 35μm, and a surface copper standard substrate is obtained. Perform dry film pattern transfer on the surface copper standard substrate, and the aperture ratio of the film is 3mil less than the design value to form an outer layer patterned substrate. Remove the edge clamps and perform hole area selective copper plating on the outer layer patterned substrate to form a 22μm hole copper reinforced substrate.

[0034] Step 7, perform inner layer pattern transfer on the hole copper reinforced substrate according to the 1OZ compensation standard to form an inner layer patterned substrate. After calibrating the etching parameters using a dummy board as the first piece, etch the inner layer patterned substrate to form a high-precision circuit substrate with a fuse line width of 2.005±0.010mm.

[0035] Step 8, print solder resist ink on the high-precision circuit substrate, and cure it at 150℃ / 60min after patterning to form a solder resist cured board. Perform electrical testing, profile numerical control milling, electroless tin plating, and mechanical bending on the solder resist cured board. The thickness of the electroless tin plating is 8μm, and the angle of the mechanical bending is 90±0.5°. After plasma cleaning, perform finished product inspection to obtain an embedded IC printed circuit board.

[0036] Example 2

[0037] The present embodiment proposes a method for preparing an embedded IC printed circuit board. Unlike Example 1, the method specifically comprises the following steps:

[0038] Step 1, take a copper block substrate, and attach a high-temperature resistant polyimide adhesive tape through a special jig to ensure that the position accuracy of the adhesive tape is ≤0.1mm. Eliminate air bubbles by a film press at a pressure of 0.5MPa to form an air bubble-eliminated sealed copper block substrate. Perform brown oxidation treatment on the air bubble-eliminated sealed copper block substrate using Atotech Bondfilm solution to form a brown copper block substrate. Bake the brown copper block substrate at 180℃ for 60min to obtain a pre-cured copper block substrate.

[0039] Step 2, take FR-4 copper-clad substrate, design the width of process edge to be 30 mm, form a process edge substrate; process the inner layer pattern of the process edge substrate with acidic copper chloride etching solution, form an inner layer pattern substrate; mill the embedded slot on the inner layer pattern substrate, the slot width is 3 mil larger than the single side of the copper block, form a substrate with copper block slot; clean the substrate with copper block slot to remove debris, form a clean slot body substrate; after the brown treatment of the clean slot body substrate, solidify for 40 min at 150℃, obtain a solidified slot body substrate.

[0040] Step 3, stack and cut 6 pieces of 1080 type PP semi-cured sheet with a resin content of 68% to form a PP plate to be processed; use a high-frequency milling cutter on the PP plate to be processed, the high-frequency milling cutter rotates at 45000 rpm, when processing an asymmetric slot body, the slot width of the electrical connection area = the bending area + 4 mil, the slot width of the non-electrical area = the bending area + 5 mm, the slot depth is 65% of the thickness of the PP plate, form a PP plate with an asymmetric stress slot.

[0041] Step 4, embed the pre-solidified copper block substrate into the slot position of the solidified slot body substrate, stack the PP plate with an asymmetric stress slot and the MOZ type copper foil, use 3 pieces of 1080 type PP on each side of the PP plate, and press the false plate, the pressure is 350 psi, the temperature is 185℃, and the time is 90 min, form a thick copper embedded laminated plate; perform X-ray alignment detection on the thick copper embedded laminated plate, the offset is ≤25 μm, obtain a qualified laminated plate; laser drill on the qualified laminated plate, the hole diameter is 0.15 mm, form a hole substrate.

[0042] Step 5, place the hole substrate in an electromagnetic field generator, set the axial magnetic field strength to 0.5 T, the alternating electric field to 10 kHz / 30 V / cm, and inject carboxylated carbon nanotube-containing epoxy-polyimide colloid with a concentration of 0.1 wt% and a viscosity of 350 cp into the hole, first pre-solidify at 80℃ / 30 min to gel the colloid and fix the nanotube array, then finally solidify at 170℃ / 60 min, form a functionalized filled substrate.

[0043] Step 6, perform chemical copper plating on the functionalized filled substrate to form a hole metallization substrate; measure the surface copper thickness of the hole metallization substrate to be 38 μm, adjust the electroplating parameters and electroplate, the surface copper thickness is 35 μm, obtain a surface copper standard substrate, perform dry film pattern transfer on the surface copper standard substrate, the film hole diameter is 3 mil smaller than the design value, form an outer layer pattern substrate, cancel the edge strip clamp, and perform hole area selective copper plating on the outer layer pattern substrate, real-time monitor the current, form a 22 μm hole copper reinforced substrate hole copper.

[0044] Step 7, perform inner layer pattern transfer on the hole copper reinforced substrate according to the 1OZ compensation standard, form an inner layer pattern substrate; calibrate the etching parameters with the false plate as the first piece, etch the inner layer pattern substrate, form a high-precision circuit substrate, the fuse line width is 2.005±0.010 mm.

[0045] Step 8, print solder resist ink on the high-precision circuit board, patternize and cure at 150℃ / 60min to form a solder resist cured board; perform electrical test, profile numerical control milling, electroless tin plating, and mechanical bending on the solder resist cured board, the thickness of the electroless tin plating is 8μm, the angle of the mechanical bending is 90±0.5°, then perform product inspection after plasma cleaning to obtain the embedded IC printed circuit board.

[0046] Example 3

[0047] The embodiment provides a preparation method of an embedded IC printed circuit board, which is used for preparing the embedded IC printed circuit board, and differs from the embodiment 1 in that the method specifically comprises the following steps:

[0048] Step 1, take a copper block substrate, paste a high-temperature-resistant polyimide adhesive tape through a special jig to ensure that the position accuracy of the adhesive tape is less than or equal to 0.1mm, and form a sealed copper block substrate with bubbles eliminated by a film press machine at a pressure of 0.5MPa to eliminate bubbles; perform brown oxidation treatment on the sealed copper block substrate with bubbles eliminated by using Atotech Bondfilm solution to form a brown copper block substrate; and obtain a pre-cured copper block substrate by baking the brown copper block substrate at 180℃ for 60min.

[0049] Step 2, cut an FR-4 copper-clad substrate to form a process edge substrate with a process edge width of 30mm; process an inner layer pattern on the process edge substrate by using an acidic copper chloride etching solution to form an inner layer pattern substrate; mill an embedded slot on the inner layer pattern substrate, the slot width is 3mil larger than the single side of the copper block to form a substrate with a copper block slot; clean the substrate with a copper block slot to remove debris to form a clean slot body substrate; and obtain a cured slot body substrate by performing brown oxidation treatment on the clean slot body substrate and curing at 150℃ for 40min.

[0050] Step 3, stack and cut 6 pieces of 1080 type PP semi-cured sheet with a resin content of 68% to form a to-be-processed PP plate; use a high-frequency milling cutter to process an asymmetric slot body on the to-be-processed PP plate, the rotational speed of the high-frequency milling cutter is 45000rpm, the slot width of the electrical connection area is equal to the bending area+4mil, the slot width of the non-electrical area is equal to the bending area+5mm, and the slot depth is 65% of the thickness of the PP plate, to form a PP plate with an asymmetric stress slot.

[0051] Step 4, embed the pre-cured copper block substrate into the slot of the cured slot body substrate, stack the PP plate with asymmetric stress slot and the MOZ type copper foil, use 3 pieces of 1080 type PP on each side of the PP plate, press the dummy plate with a pressure of 350 psi and a temperature of 185℃ for 90 min to form a thick copper embedded laminated plate; perform X-ray alignment detection on the thick copper embedded laminated plate, and the offset is ≤25μm to obtain a qualified laminated plate; laser drill holes on the qualified laminated plate with a hole diameter of 0.15mm to form a hole substrate.

[0052] Step 5, perform chemical copper plating on the hole substrate to form a hole metallization substrate; measure the surface copper thickness of the hole metallization substrate, which is 38μm, adjust the electroplating parameters and electroplate, and the surface copper thickness is 35μm to obtain a surface copper standard substrate; perform dry film pattern transfer on the surface copper standard substrate, and the film hole diameter is 3 mil smaller than the design value to form an outer layer pattern substrate; cancel the edge clamp, and perform hole area selective copper plating on the outer layer pattern substrate to form a 22μm hole copper reinforced substrate hole copper.

[0053] Step 6, perform inner layer pattern transfer on the hole copper reinforced substrate according to the 1OZ compensation standard to form an inner layer pattern substrate; calibrate the etching parameters with the dummy plate as the first piece, etch the inner layer pattern substrate to form a high-precision circuit substrate, and the fuse line width is 2.005±0.010mm.

[0054] Step 7, print solder resist ink on the high-precision circuit substrate, cure it at 150℃ / 60min after patterning to form a solder resist cured plate; perform electrical testing, profile numerical control milling, chemical tin plating, and mechanical bending on the solder resist cured plate; the thickness of the chemical tin plating is 8μm, the angle of the mechanical bending is 90±0.5°, and then perform finished product inspection after plasma cleaning to obtain an embedded IC printed circuit board.

[0055] Example 4

[0056] The embodiment provides a preparation method of an embedded IC printed circuit board, which is used for preparing the embedded IC printed circuit board.

[0057] Step 1, take a copper block substrate, paste a high-temperature polyimide adhesive tape through a special jig to ensure that the position accuracy of the adhesive tape is ≤0.1mm, and remove the bubbles by a film press machine at a pressure of 0.5MPa to form a bubble-eliminated sealed copper block substrate; perform brown oxidation treatment on the bubble-eliminated sealed copper block substrate using Atotech Bondfilm solution to form a brown copper block substrate; and bake the brown copper block substrate at 180℃ for 60min to obtain a pre-cured copper block substrate.

[0058] Step 2, take FR-4 copper-clad substrate, design the process edge width of 30 mm to form a process edge substrate; process the inner layer pattern of the process edge substrate with acidic copper chloride etching solution to form an inner layer pattern substrate; mill the embedded slot on the inner layer pattern substrate, the slot width is 3 mil larger than the single side of the copper block to form a substrate with a copper block slot; clean the substrate with a copper block slot to remove debris to form a clean slot body substrate; after the brown treatment of the clean slot body substrate, solidify for 40 min at 150°C to obtain a solidified slot body substrate.

[0059] Step 3, stack and cut 6 pieces of 1080 type PP semi-cured sheet with a resin content of 68% to form a PP plate to be processed; process a uniform slot body on the PP plate to be processed with a high-frequency milling cutter, the high-frequency milling cutter speed is 45000 rpm, the electrical zone = the bending zone = the non-electrical zone, the slot width is uniformly increased by 4 mil to form a PP plate with a uniform slot body.

[0060] Step 4, embed the pre-solidified copper block substrate into the slot position of the solidified slot body substrate, stack the PP plate with asymmetric stress slots and MOZ type copper foil, use 3 pieces of 1080 type PP on each side of the PP plate, and press the false plate, the pressure is 350 psi, the temperature is 185°C, and the time is 90 min to form a thick copper embedded laminated plate; perform X-ray alignment detection on the thick copper embedded laminated plate, the offset is ≤25 μm to obtain a qualified laminated plate; laser drill holes on the qualified laminated plate, the hole diameter is 0.15 mm to form a hole substrate.

[0061] Step 5, inject epoxy resin colloid into the holes of the hole substrate, the epoxy resin colloid does not contain nano material additives, and is solidified at 150°C for 90 min at a time to form a traditional filled substrate.

[0062] Step 6, perform chemical copper plating on the traditional filled substrate to form a hole metallization substrate; measure the surface copper thickness of the hole metallization substrate, which is 38 μm, adjust the electroplating parameters, and electroplate to obtain a surface copper thickness of 35 μm to obtain a surface copper standard substrate; perform dry film pattern transfer on the surface copper standard substrate, the film hole diameter is 3 mil smaller than the design value to form an outer layer pattern substrate, cancel the edge strip clamp, and implement hole area selective copper plating on the outer layer pattern substrate to form a 22 μm hole copper reinforced substrate hole copper.

[0063] Step 7, transfer the inner layer pattern of the hole copper reinforced substrate according to the 1OZ compensation standard to form an inner layer pattern substrate; calibrate the etching parameters with the false plate as the first piece, etch the inner layer pattern substrate to form a high-precision circuit substrate, and the fuse line width is 2.005±0.010 mm.

[0064] Step 8, print solder resist ink on the high-precision circuit substrate, after patterning, cure at 150℃ / 60min to form a solder resist cured board; conduct electrical test, profile numerical control milling, electroless tin plating, mechanical bending on the solder resist cured board, the thickness of the electroless tin plating is 8μm, the angle of the mechanical bending is 90±0.5°, then conduct finished product inspection after plasma cleaning to obtain the embedded IC printed circuit board.

[0065] In Example 2, compared with Comparative Example 1, when the axial magnetic field strength is reduced from 1.0T to 0.5T and the alternating electric field strength is reduced by 40%, the carbon nanotubes cannot be arranged along the axial direction of the channel due to insufficient driving force, and are in a disordered agglomeration state; at the same time, the microfluidic oscillation intensity is weakened, and the bubble removal efficiency is greatly reduced, resulting in the formation of a continuous air pocket network in the filling body. This structural defect makes the hole conductivity decay from 5.2×10 4 S / m to 2.8×10 4 S / m, and becomes a crack source under thermal stress, and the thermal cycle life is shortened by 56%.

[0066] In Example 3, compared with Comparative Example 1, the electromagnetic field cooperative filling step is directly omitted, and the inner wall of the deep hole lacks nano-enhanced structure, and the copper layer and the resin matrix form a weak interface of mechanical interlocking. In the temperature cycle, the copper-resin interface is repeatedly sheared due to the difference in CTE, causing the copper layer in the hole to peel off early (the bonding force is only 0.3N / mm), and the unremoved bubbles expand under high pressure, resulting in 35% of the filled holes appearing microcracks and expanding into conductive failure channels, and the product life is drastically reduced.

[0067] In Example 4, compared with Comparative Example 1, the uniform PP slot completely loses the self-adaptive ability of thermal expansion: the resin forms a stress concentration area (peak stress up to 285MPa) at the edge of the copper block during lamination, causing interface microcracks; the ordinary resin filling body lacks nano-enhanced phase, and the thermal conductivity / conductivity is only 25% of Example 1. More seriously, the single curing process makes the resin shrinkage rate as high as 1.8%, causing micron-level separation gaps at the hole wall interface.

[0068] In summary, Example 1 of the present application realizes the leap from physical basis to system integration of high-density embedded substrates through the three-dimensional synergistic innovation of "topological structure-molecular engineering-dynamic control"; in the aspect of heterogeneous material fusion, the asymmetric PP stress slot of electrical area (4mil)>bending area>non-electrical area (5mm) forms a self-adaptive expansion buffer network, which suppresses the thermal stress peak at the edge of the copper block to below 200MPa, and forms micron-level anchoring structures at the interface through a gradient curing process, making the bonding strength break through 18.5MPa, which is 2.3 times of the industry standard; in the aspect of deep hole functionalization of the core layer, 1.0T axial magnetic field drives carboxylated carbon nanotubes to arrange along the hole axis, constructing a longitudinal 5.2×10 4The quantum tunneling conductive path of S / m - the microfluidic oscillation induced by the synchronous 15 kHz alternating electric field produces cavitation effect, removes the bubbles in the hole and locks the nano topological structure through step solidification, so that the thermal management efficiency is improved by 300%; at the system level manufacturing level, the functional substrate forms a precise closed loop with the feedback electroplating of the surface copper and the false plate etching calibration, realizes the golden triangle balance of electric conduction / heat dissipation / mechanical stability.

[0069] When the electromagnetic field parameters of embodiment 2 are weakened, the carbon nanotube arrangement is disordered, the conductive path is broken, and the performance drops sharply; when the functional filling of embodiment 3 is deleted, the hole wall interface is degraded to the original state of mechanical occlusion, and the service life is less than 20%; when the homogeneous structure of embodiment 4 is adopted, the thermal stress concentration causes poor delamination. Therefore, the "asymmetric slot body directional pressure release-electromagnetic field quantization arrangement-microfluidic cavitation effect" three-in-one technical chain of embodiment 1 can solve the three major industry diseases of thermal expansion delamination, deep hole bubble defect, and hole surface copper thickness conflict.

[0070] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0071] The above-described embodiments only express several embodiments of the present application, which are described in detail and specifically, but should not be understood as limiting the scope of the present application. It should be noted that for those skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A method for fabricating an embedded IC printed circuit board, characterized in that, The method includes the following steps: Step 1: Apply tape to the copper block substrate using a special fixture, and then use a laminator to remove air bubbles to form a sealed copper block substrate; perform browning treatment on the sealed copper block substrate to form a browned copper block substrate; bake and cure the browned copper block substrate to obtain a pre-cured copper block substrate. Step 2: Cut the copper-clad substrate and design the process edges to form a process edge substrate; The inner layer pattern is etched on the process edge substrate to form an inner layer pattern substrate; an embedding groove is milled on the inner layer pattern substrate to form a substrate with a copper block groove; the substrate with the copper block groove is cleaned to obtain a clean tank substrate; the clean tank substrate is browned and baked to obtain a cured tank substrate. Step 3: Stack and cut the PP sheets to form the PP sheet to be processed; use a high-frequency milling cutter to process the asymmetric groove on the PP sheet to be processed to obtain the PP sheet with asymmetric stress groove; Step 4: Embed the pre-cured copper block substrate into the slot of the curing tank substrate, stack the PP board with asymmetric stress groove and copper foil, and press the dummy board to form a thick copper embedded laminate; perform X-ray alignment inspection on the thick copper embedded laminate to obtain a qualified laminate; process through holes on the qualified laminate to form a perforated substrate. Step 5: Place the perforated substrate in a pulsed magnetic field generator and apply an axial magnetic field and an alternating electric field to cause the residual metal particles in the holes to align along the magnetic field lines. Then, inject an epoxy-polyimide composite colloid containing carboxylated carbon nanotubes into the holes. Under the action of the magnetic field, the carbon nanotubes are arranged vertically along the hole axis. At the same time, the alternating electric field induces the colloid to generate microfluidic oscillations, eliminating air bubbles in the holes. Then, the epoxy-polyimide composite colloid is cured in steps to obtain a functionalized filled substrate. Step 6: Perform chemical copper plating on the functionalized filler substrate to form a via metallized substrate; measure the surface copper thickness of the via metallized substrate and adjust the electroplating parameters accordingly; after electroplating, obtain a substrate with acceptable surface copper thickness; perform pattern transfer on the substrate with acceptable surface copper thickness to obtain an outer pattern substrate. Eliminate the edge clamps and monitor the current in real time. Perform selective copper plating on the hole areas of the outer layer patterned substrate to form a copper-reinforced substrate. Step 7: Transfer the inner layer pattern of the copper-reinforced via substrate to obtain the inner layer pattern substrate; Using a dummy board as the first piece, the etching parameters are calibrated, and the inner layer pattern substrate is etched to form a high-precision circuit substrate. Step 8: Print solder resist ink and pattern it on a high-precision circuit board to obtain a solder resist curing board; perform electrical testing, CNC milling, chemical tin plating and mechanical bending on the solder resist curing board, and finally clean and package it to obtain an embedded IC printed circuit board.

2. The method for fabricating an embedded IC printed circuit board according to claim 1, characterized in that, In step 1, a special fixture ensures that the tape position accuracy is ≤0.1mm, the laminator removes air bubbles with a pressure of 0.4-0.6MPa, and the PNL side tube hole is sealed with tape.

3. The method for fabricating an embedded IC printed circuit board according to claim 1, characterized in that, In step 2, the process edge width is 30mm, and the groove width of the embedded groove is 3±0.5mil larger than the single side of the copper block.

4. The method for fabricating an embedded IC printed circuit board according to claim 1, characterized in that, In step 3, the PP sheet stack consists of 6 sheets of 1080 type PP with a resin content of 68%; When machining asymmetrical grooves, the groove width in the electrical connection area is 4 mil larger than that in the bending area, and the groove width in the non-electrical area is 5 mm larger than that in the bending area. Phenolic resin boards are used to clamp the PP during machining, and the groove depth is 60-70% of the thickness of the PP board.

5. The method for fabricating an embedded IC printed circuit board according to claim 1, characterized in that, In step 4, three 1080-type PP sheets are used on each side of the PP board with asymmetric stress grooves, and MOZ copper foil is used. Two dummy boards with the same thickness and surface copper are pressed together simultaneously.

6. The method for fabricating an embedded IC printed circuit board according to claim 1, characterized in that, In step 5, the applied axial magnetic field and alternating electric field are specifically an axial magnetic field of 0.5-1.2T and an alternating electric field of 10-20kHz, and the viscosity of the epoxy-polyimide composite colloid containing carboxylated carbon nanotubes is 200-500cp.

7. The method for fabricating an embedded IC printed circuit board according to claim 1, characterized in that, In step 5, the epoxy-polyimide composite colloid is cured in a stepwise manner as follows: first, it is pre-cured at 80°C to gel and fix the nanotube array, and then it is finally cured at 180°C.

8. The method for fabricating an embedded IC printed circuit board according to claim 1, characterized in that, In step 6, the copper thickness of the substrate with surface copper is controlled at 31-41μm; a clamp ammeter is used for real-time current monitoring, and the copper plating thickness of the holes is controlled at ≥20μm.

9. The method for fabricating an embedded IC printed circuit board according to claim 1, characterized in that, In step 7, the inner layer pattern transfer is carried out according to the 1OZ inner layer compensation standard. The inner layer pattern transfer is produced using hole spot film that is 3mil smaller than the single side of the hole, while the process edge is controlled at 8mm.

10. The method for fabricating an embedded IC printed circuit board according to claim 1, characterized in that, In step 7, the inner layer pattern substrate is etched using an acidic etching solution, and the width of the key lines is controlled to be 2.0 ± 0.015 mm.

11. A high-definition outdoor display screen printed circuit board, characterized in that, It is prepared by the method of preparing an embedded IC printed circuit board as described in any one of claims 1-10.

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