A method for manufacturing a board-level fan-out packaging structure

Abstract

The present invention discloses a method for manufacturing a board-level fan-out packaging structure, comprising the steps of: substrate windowing, first temporary bonding, first chip attachment, first pressing and filling with resin, second temporary bonding, second chip attachment, second pressing and filling with resin, first pre-curing, blind hole processing, circuit production, resin insulation layer processing, production of an intermediate circuit, debonding, third pressing and filling with resin, curing, etc. The processes of the first and second substrates from chip attachment, formation of the first and second resin layers to production of the intermediate circuit are all completed under the support of a support plate, and the supporting function of the support plate can prevent excessive warping and repeated bending of the substrate during processing. The resin in the board-level fan-out packaging structure is in a semi-cured state before curing, so that the processing is completed in a low-warping state, avoiding warping and excessive bending of the substrate during the processing of the board-level fan-out packaging structure, and thus avoiding cracking and delamination of the formed structure.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a method for manufacturing a board-level fan-out packaging structure. Background Art

[0002] In the prior art, during the manufacturing process of the board-level fan-out packaging structure, the chip is temporarily bonded on a large-format carrier board. After molding, the chip embedded in the molding resin and the plastic sealing board formed by the molding are debonded, and then the embedded chip is subjected to multi-layer wiring on the surface of the plastic sealing board with the chip in front, and the layer units are cut to form a board-level fan-out packaging structure.

[0003] The board-level fan-out package forms POP (Package-on-Package) interconnection, which requires manufacturing conductive through-holes penetrating the plastic package in the fan-out package structure, and manufacturing pads on the back of the plastic package to form the front and back interconnections based on the board-level fan-out package.

[0004] Furthermore, after wiring the resin surface of a fan-out package, the resin board containing the embedded chip experiences significant warping. This warping increases with the number of wiring layers. Typically, after more than three layers, wiring becomes difficult, making circuit processing difficult. Furthermore, the conductive vias in the resin board require extra-thick copper pillar plating, making the manufacturing process extremely challenging. Summary of the Invention

[0005] The object of the present invention is to provide a method for manufacturing a board-level fan-out packaging structure, so as to reduce substrate warping during processing, improve processing efficiency, and reduce manufacturing costs.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A method for manufacturing a board-level fan-out packaging structure, comprising:

[0008] Substrate windowing: cavities for accommodating chips are opened on multiple substrates, and circuits are arranged on both the front and back sides of the substrates and the circuits on the front and back sides are interconnected;

[0009] A first temporary bonding step is performed to bond the first surface of the first substrate having the accommodating cavity to the first bonding material layer, wherein a support plate is fixed to a side of the first bonding material layer facing away from the first substrate;

[0010] A first chip mounting step is to place the chip in the receiving cavity of the first substrate;

[0011] a first pressing and filling resin, pressing and filling the resin on the second surface of the first substrate to form a first resin layer;

[0012] Second temporary bonding: providing a second bonding material layer on a side of the support plate away from the first bonding material layer, and bonding the second bonding material layer to the first surface of the second substrate having the accommodating cavity;

[0013] A second chip mounting step is to place the chip in the receiving cavity of the second substrate;

[0014] a second pressing and filling resin, pressing and filling the second surface of the second substrate with resin to form a second resin layer;

[0015] The first pre-curing cures the resin in the structure formed in the previous step to more than 50%;

[0016] Blind hole processing: opening blind holes on the upper and lower surfaces of the structure formed in the previous step;

[0017] Circuit fabrication: processing circuits on the upper and lower surfaces of the structure formed in the previous step;

[0018] Resin insulation layer processing, providing a resin insulation layer on both the upper and lower surfaces of the structure formed in the previous step, and performing pre-curing to cure the resin insulation layer formed in this step to more than 50%;

[0019] Fabricating an intermediate circuit, repeating N times of blind hole processing, circuit fabrication, and resin insulation layer processing steps, where N is greater than or equal to 0, to form N layers of intermediate circuits, without pre-curing in the Nth resin insulation layer processing step, and pre-curing after laminating copper foil on the surface of the resin insulation layer formed in the Nth resin insulation layer processing step, so that the resin insulation layer in the formed structure is cured to more than 50%;

[0020] Laminating the copper foil on the surface of the resin insulation layer of the Nth layer of the intermediate circuit from the inside to the outside of the structure formed in the previous step, and pre-curing the resin insulation layer in the structure to cure to more than 50%;

[0021] Debonding: debonding the first bonding material layer from the first surface of the first substrate, and debonding the second bonding material layer from the first surface of the second substrate;

[0022] a third pressing and embedding resin, pressing and embedding resin on the first surface of the first substrate and pressing copper foil on the surface of the formed resin layer to obtain a first temporary structure, and pressing and embedding resin on the first surface of the second substrate and pressing copper foil on the surface of the formed resin layer to obtain a second temporary structure;

[0023] The second pre-curing cures the resin in the first temporary structure and the second temporary structure to more than 50%;

[0024] Curing: the structure formed in the previous step is placed in a laminator, clamped by mirror steel plates, under a preset vacuum degree and preset pressure, so that the resin in the structure is cured to more than 90%;

[0025] Fabricating the outer layer circuit, performing blind hole processing and circuit fabrication steps on the cured structure to form the outer layer circuit;

[0026] Making a solder resist layer, and making a solder resist layer on the surface of the outer layer circuit;

[0027] A coating is applied to the surface of the structure formed after the solder resist layer is formed.

[0028] In one implementation, the first bonding material layer includes a foaming film, a support film, and a pressure-sensitive adhesive film stacked in sequence, and the foaming film of the first bonding material layer is bonded to the first surface of the first substrate, and the pressure-sensitive adhesive film of the first bonding material layer is bonded to the support plate; and / or,

[0029] The second bonding material layer includes a foaming film, a support film and a pressure-sensitive adhesive film stacked in sequence, and the foaming film of the second bonding material layer is bonded to the first surface of the second substrate, and the pressure-sensitive adhesive film of the second bonding material layer is bonded to the side of the support plate facing away from the first bonding material layer.

[0030] In one implementation, the first pre-curing is specifically: curing the resin in the structure formed in this step to 50%-70%; or, the first pre-curing is specifically: placing the formed structure in a constant temperature environment of 130°C-155°C for 30min-60min to pre-cure the resin in the structure.

[0031] In one implementation, the pre-curing in the resin insulation layer processing step is specifically: curing the resin insulation layer in the structure to a degree of 50%-70%; or, the pre-curing in the resin insulation layer processing step is specifically: placing the formed structure in a constant temperature environment of 130°C-155°C for 30min-60min to pre-cure the resin in the structure.

[0032] In one implementation, the curing is specifically as follows: placing the formed structure in a laminator, clamping it between two mirror steel plates, the pressure of the mirror steel plates is 0.1MPa-0.5MPa, in an environment with a constant temperature of 190℃-210℃ and a vacuum degree of 1Pa-15Pa, and maintaining it for 50min-70min to cure the resin in the structure.

[0033] In one implementation, the raw materials used in the first pressing and filling resin step, the second pressing and filling resin step, the resin insulation layer processing step, and the third pressing and filling resin step are all ABF resin sheets, and the ABF resin sheet includes an ABF main layer, an OPP film attached to the first side of the ABF main layer, and a PET film attached to the second side of the ABF main layer.

[0034] In one implementation, the first resin embedding step comprises: removing the OPP film of the ABF resin sheet, and laminating the first side of the ABF resin sheet to the second surface of the first substrate to form a first resin layer, with the PET film remaining on the side of the first resin layer facing away from the first substrate;

[0035] The second resin embedding step is specifically to remove the OPP film of the ABF resin sheet and to press the first side of the ABF resin sheet onto the second surface of the second substrate to form a second resin layer, with the PET film remaining on the side of the second resin layer facing away from the second substrate.

[0036] In one implementation, the manufacturing of the outer layer circuit further includes the step of corroding the copper foil to remove the copper foil on the surface of the structure formed in the previous step.

[0037] In one implementation, after the debonding step, the method further includes: cleaning, cleaning the first surface of the first substrate and the first surface of the second substrate.

[0038] In one implementation, the curing temperature of the first pre-curing and the curing temperature of the pre-curing in the resin insulation layer processing step are lower than the debonding temperature of the first bonding material layer and the second bonding material layer.

[0039] In this application, since the circuits are arranged on both sides of the substrate and interconnected, this provides advantages for subsequent board-level fan-out packaging to form POP (Package-on-Package) interconnections. This avoids the subsequent step of manufacturing conductive through-holes. By leveraging the substrate's existing through-hole processing and mature manufacturing processes, the high-aspect-ratio copper pillar manufacturing technology is avoided, reducing processing difficulty. Furthermore, during the intermediate circuit manufacturing process, the support plate is symmetrically processed with identical wiring and insulation layers on both sides. This results in a symmetrical stress distribution throughout the entire sandwich temporary bonding structure, resulting in extremely low warpage during multi-layer wiring processing and preventing issues with processing due to basic warpage. Furthermore, the first pre-curing step is performed only after the first and second resin embedding steps are completed. A pre-curing step is performed after each intermediate circuit layer is processed and the resin insulation layer is applied to the circuit surface. This pre-curing step is not fully cured until all the resin is embedded and then cured, ultimately curing the structure to at least 90% resin. The resin in the board-level fan-out packaging structure is in a semi-cured state before curing. At this time, the modulus of the resin material in the board-level fan-out packaging structure is low, and the substrate is in a low-stress and low-warpage state. In this way, the process of chip mounting, forming the first resin layer and the second resin layer, making the intermediate circuit to the third pressing and filling resin is completed in a low-warpage state, avoiding warping and excessive bending of the substrate during the processing of the board-level fan-out packaging structure, and thus avoiding structural cracking and delamination.

[0040] In addition, in the manufacturing method of the board-level fan-out packaging structure of the present application, a first bonding material layer and a first substrate are arranged on one side of the support plate, and a second bonding material layer and a second substrate are arranged on the other side of the support plate, that is, the processing structures on both sides of the support plate are symmetrically arranged, which fully utilizes the supporting function of the support plate and processes two board-level fan-out packaging structures at the same time, thereby improving manufacturing efficiency and reducing processing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0042] Figure 1 A schematic flow chart of a method for manufacturing a board-level fan-out packaging structure provided by an embodiment of the present invention;

[0043] Figure 2 The structure of the first substrate formed after the substrate windowing step provided in an embodiment of the present invention;

[0044] Figure 3 The structure formed after the first temporary bonding step provided in an embodiment of the present invention;

[0045] Figure 4 The structure formed after the first chip mounting step provided in the embodiment of the present invention;

[0046] Figure 5 The structure formed after the first pressing and embedding resin step provided in the embodiment of the present invention;

[0047] Figure 6 The structure formed after the second temporary bonding step provided by the embodiment of the present invention;

[0048] Figure 7 The structure formed after the second chip mounting step provided in the embodiment of the present invention;

[0049] Figure 8 The structure formed after the second pressing and embedding resin step provided in the embodiment of the present invention;

[0050] Figure 9 The structure formed after the blind hole processing step provided in the embodiment of the present invention;

[0051] Figure 10 The structure formed after the film stripping step provided in the embodiment of the present invention;

[0052] Figure 11 The structure formed after the circuit manufacturing steps provided in the embodiment of the present invention;

[0053] Figure 12 The structure formed after the step of manufacturing the intermediate circuit provided in the embodiment of the present invention;

[0054] Figure 13 A schematic diagram of a first substrate after a debonding step according to an embodiment of the present invention;

[0055] Figure 14 A schematic diagram of a first temporary structure obtained after the third step of pressing and embedding the resin according to an embodiment of the present invention;

[0056] Figure 15 A schematic diagram of a first temporary structure after a blind hole is machined according to an embodiment of the present invention;

[0057] Figure 16 A schematic diagram of the steps of manufacturing an outer layer circuit according to an embodiment of the present invention;

[0058] Figure 17 A schematic diagram of the steps of making a solder mask layer according to an embodiment of the present invention;

[0059] Figure 18 A schematic structural diagram of the first bonding material layer or the second bonding material layer provided in an embodiment of the present invention.

[0060] Reference numerals:

[0061] 1-first substrate, 1a-accommodating cavity, 1b-substrate circuit, 2-first bonding material layer, 3-support plate, 4-chip, 5-first resin layer, 6-second substrate, 7-second bonding material layer, 8-second resin layer, 9-blind hole, 10-inner layer circuit, 11-middle circuit, 12-third resin layer, 13-outer layer circuit, 14-solder mask layer;

[0062] a-foaming film, b-support film, c-pressure-sensitive adhesive film, d-PET film. DETAILED DESCRIPTION

[0063] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0064] It should be noted that when an element is referred to as being “fixed on” or “disposed on” another element, it may be directly on the other element or indirectly on the other element. When an element is referred to as being “connected to” another element, it may be directly connected to the other element or indirectly connected to the other element.

[0065] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Thus, a feature specified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined. "Several" means one or more, unless otherwise specifically defined.

[0066] In the description of the present invention, it should be understood that the terms "up", "down", "front", "back", "left", "right", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0067] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and may encompass internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0068] See also Figure 1 , Figure 1 This is a flow chart of an embodiment provided by the present invention. The method for manufacturing a board-level fan-out packaging structure in this embodiment includes the following steps:

[0069] S1: Opening windows on substrates: opening cavities 1a for accommodating chips 4 on multiple substrates. Circuits are arranged on both the front and back sides of the substrates and are interconnected.

[0070] Specifically, step S1 may include forming accommodating cavities 1a on two substrates, namely, the first substrate 1 and the second substrate 6. That is, accommodating cavities 1a are formed on both the first substrate 1 and the second substrate 6, so as to facilitate placement of the chip 4 in the accommodating cavities in subsequent steps.

[0071] In addition, in this step, Figure 2 The middle substrate has a substrate circuit 1b. Circuits are arranged on both the front and back sides of the substrate, and the circuits on the front and back sides of the substrate are electrically connected to each other, so that after multiple wiring operations are performed on the front and back sides of the substrate, the multi-layer wiring on the front and back sides are electrically connected. A window is opened in a substrate with interconnected front and back wiring. The substrate with interconnected front and back wiring is manufactured using conventional substrate manufacturing processes. Multi-layer wiring is performed on the upper and lower surfaces of the substrate. The front and back wiring layers are interconnected through the through holes of the middle core board to form the front and back wiring layers. This double-sided wiring interconnection substrate can be a substrate with a core board or a coreless substrate without a core board.

[0072] Specifically, the two sides of the substrate along the thickness direction of the substrate are the first side and the second side respectively, or when the substrate is placed horizontally, that is, when the thickness direction of the substrate is along the vertical direction, the lower surface and the upper surface of the substrate are the first side and the second side respectively. Figure 2 shown.

[0073] The substrate can be made of BT (Bismaleimide Triazine) resin or FR4. BT resin has a very high glass transition temperature, excellent dielectric properties, low thermal expansion, and good mechanical properties, making it suitable for substrate production. FR4 is a designation for a flame-resistant material grade, indicating that the resin must be able to self-extinguish after combustion. Of course, the substrate can also be made of other materials, which are not limited here.

[0074] S2: first temporary bonding, bonding the first surface of the first substrate 1 having the accommodating cavity 1 a to the first bonding material layer 2, with a support plate 3 fixed to a side of the first bonding material layer 2 facing away from the first substrate 1;

[0075] That is, the first bonding material layer 2 is bonded to the first surface of the first substrate 1 having the accommodating cavity 1a. In this embodiment, the first surface of the first substrate 1 may be the lower surface of the first substrate 1. A support plate 3 is fixed to the side of the first bonding material layer 2 facing away from the first substrate 1.

[0076] like Figure 18 As shown, the first bonding material layer 2 may include a foam film a, a support film b, and a pressure-sensitive adhesive film c stacked in sequence, with the foam film a of the first bonding material layer 2 bonded to the first surface of the first substrate 1. At the debonding temperature, the foam film a can be debonded in just a few minutes, and the support plate 3 can fall off automatically, completing the debonding process. This is easy to operate and does not require any special equipment.

[0077] A support plate 3 is fixed to the side of the first bonding material layer 2 facing away from the first substrate 1, and the pressure-sensitive adhesive film c of the first bonding material layer 2 is bonded to the support plate 3, that is, the first bonding material layer 2 is located between the support plate 3 and the first substrate 1. The structure formed after the first temporary bonding step is as follows: Figure 3 As shown. In this embodiment, the first bonding material layer 2 can be 31950E temporary bonding adhesive produced by Nitto Corporation with 210°C heat-foamed debonding. Of course, other temporary bonding adhesives can be selected according to actual conditions and are not limited here. Of course, the first bonding material layer 2 can also be a single-layer film structure or other types of multi-layer film structures, which are not limited here.

[0078] It should be noted here that the first bonding material layer 2 can be bonded to the support plate 3 first and then to the first substrate 1. In this way, the first bonding material layer 2 is first bonded to the support plate 3 for standby use. Of course, the first bonding material layer 2 can also be bonded to the first substrate 1 first and then to the support plate 3. This is not limited here.

[0079] The support plate 3 may be a plate with high rigidity, such as a double-sided copper-clad plate, a metal plate, a glass plate, or a ceramic plate. Alternatively, the support plate 3 may be made of BT resin, or a double-sided copper-clad plate made of BT resin. The thickness of the support plate 3 may be greater than or equal to 0.5 mm. Specifically, the thickness of the support plate 3 may be 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, etc. This ensures the strength of the support plate 3 and prevents warping of the first substrate 1 and the second substrate 6 during processing.

[0080] S3: First attach the chip 4, placing the chip 4 in the accommodating cavity 1a of the first substrate 1;

[0081] Chip 4 is placed in cavity 1a of first substrate 1. In this step, the electrode side of chip 4 can be oriented away from first bonding material layer 2, meaning the chip 4 is placed with its electrode facing upward. Alternatively, the chip 4 can be placed with its electrode facing downward. If cavity 1a is a through hole, chip 4 can contact first bonding material layer 2. When the electrode side of chip 4 faces downward, its electrode contacts first bonding material layer 2.

[0082] When the first bonding material layer 2 includes a foaming film a, a support film b, and a pressure-sensitive adhesive film c stacked in sequence, the chip 4 can be in contact with the foaming film a of the first bonding material layer 2. Specifically, when the electrode side of the chip 4 is facing downward, its electrode is in contact with the foaming film a of the first bonding material layer 2. The structure formed after the chip 4 bonding step is as follows: Figure 4 shown.

[0083] Preferably, when the chip 4 is attached to the accommodating cavity 1a of the first substrate 1, the electrode side of the chip 4 can be oriented toward the side away from the first bonding material layer 2, that is, the electrode of the chip 4 faces upward, so that the foaming film a of the first bonding material layer 2 does not contact the chip 4 electrode, but contacts the back of the chip 4, which can prevent the surface of the chip 4 electrode from being contaminated, causing contamination to cause contaminants to be buried in the substrate and cause serious reliability problems. Alternatively, the surface of the chip 4 has a protective film to prevent the surface of the chip 4 electrode from being contaminated. After debonding, the protective film on the surface of the chip 4 can be removed. The protective film can be a film of copper foil or other materials.

[0084] S4: First pressing and filling resin, pressing and filling resin on the second surface of the first substrate 1 to form a first resin layer 5;

[0085] That is, the second surface of the first substrate 1 is pressed and filled with resin, and the filled resin forms a first resin layer 5. In this embodiment, the second surface of the first substrate 1 can be the upper surface of the first substrate 1. The second surface of the first substrate 1 is pressed and filled with resin, and specifically, a vacuum laminator can be used to press the resin on the second surface of the first substrate 1. During the pressing and filling process of the resin, the resin fills the gaps between the circuits on the surface of the first substrate 1 and the gaps around the chip 4. The structure formed after the first pressing and filling step is as follows: Figure 5 shown.

[0086] The surface of the first resin layer 5 may be provided with a protective film. Specifically, the protective film may be removed before or after the blind hole 9 processing step. The protective film may prevent the first resin layer 5 from being contaminated.

[0087] An ABF (Ajinomoto Buildup Film) resin sheet can be used in the first resin lamination step. The ABF resin sheet includes an ABF layer, an OPP (O-phenylphenol) film laminated to a first side of the ABF layer, and a PET (polyethylene glycol terephthalate) film laminated to a second side of the ABF layer.

[0088] In this first resin embedding step, the OPP film of the ABF resin sheet is removed, and the first side of the ABF resin sheet is laminated to the second side of the first substrate 1 to form a first resin layer 5. The PET film d remains on the side of the first resin layer 5 facing away from the first substrate 1. Specifically, in this step, the OPP film of the ABF resin sheet is removed, while the PET film d remains. The ABF resin sheet, with the OPP film removed, is laminated to the second side of the first substrate 1.

[0089] Specifically, a vacuum laminator can be used for low-temperature vacuum lamination to press the ABF resin sheet with the OPP film removed onto the second surface of the first substrate 1. In this step, the ABF resin sheet is only bonded and leveled in the vacuum laminator. The vacuum laminator includes a vacuum laminating section and a leveling section. The vacuum laminating section is mainly used to press the ABF resin sheet onto the second surface of the first substrate 1. Since the surface of the inner layer circuit is uneven, the surface of the ABF resin sheet is still uneven after lamination by the vacuum laminating section, and then the leveling section levels the ABF resin sheet to make the surface of the ABF resin sheet flat.

[0090] The resin may be a GXT31 ABF resin sheet. Alternatively, the resin may be a prepreg (prepreg) sheet or a copper-clad RCC (resin coated copper) sheet, the protective film of which is a copper foil layer.

[0091] S5: second temporary bonding, disposing a second bonding material layer 7 on the side of the support plate 3 facing away from the first bonding material layer 2, and bonding the second bonding material layer 7 to the first surface of the second substrate 6 having the accommodating cavity 1a;

[0092] That is, the second bonding material layer 7 is bonded to the side of the support plate 3 facing away from the first bonding material layer 2, and the second bonding material layer 7 is bonded to the first surface of the second substrate 6. In this embodiment, the first surface of the second substrate 6 can be the upper surface of the second substrate 6.

[0093] like Figure 18As shown, the second bonding material layer 7 may also include a foam film a, a support film b, and a pressure-sensitive adhesive film c stacked in sequence, with the foam film a of the second bonding material layer 7 bonded to the first surface of the second substrate 6. At the debonding temperature, the foam film a can be debonded in just a few minutes, and the support plate 3 can fall off on its own. Debonding is easy to perform and does not require any special equipment.

[0094] The pressure-sensitive adhesive film c of the second bonding material layer 7 is bonded to the support plate 3, that is, the second bonding material layer 7 is located between the support plate 3 and the second substrate 6. The structure formed after the second temporary bonding step is as follows: Figure 6 In this embodiment, the second bonding material layer 7 can be 31950E temporary bonding adhesive produced by Nitto, which is heat-foamed and debonded at 200°C-210°C. Of course, other temporary bonding adhesives can be selected according to actual conditions, and this is not limited here. Of course, the second bonding material layer 7 can also be a single-layer film structure or other types of multi-layer film structures, and this is not limited here.

[0095] It should be noted here that the second bonding material layer 7 can be bonded to the support plate 3 first and then to the second substrate 6. In this way, the second bonding material layer 7 can be bonded to the support plate 3 first for standby use. Of course, the second bonding material layer 7 can also be bonded to the second substrate 6 first and then to the support plate 3. This is not limited here.

[0096] S6: Second chip 4 is attached, and the chip 4 is placed in the receiving cavity 1a of the second substrate 6;

[0097] Chip 4 is placed in cavity 1a of second substrate 6. In this step, the electrode side of chip 4 can be oriented away from second bonding material layer 7, meaning the chip 4 is placed with its electrode facing downward. Alternatively, the chip 4 can be placed with its electrode facing upward. If cavity 1a is a through hole, chip 4 can contact second bonding material layer 7. When the electrode side of chip 4 faces upward, its electrode contacts second bonding material layer 7.

[0098] When the second bonding material layer 7 includes a foaming film a, a supporting film b, and a pressure-sensitive adhesive film c stacked in sequence, the chip 4 can be in contact with the foaming film a of the second bonding material layer 7, so that the chip 4 can be fixed in the accommodating cavity 1a by using the foaming film a. Specifically, when the electrode side of the chip 4 is facing upward, its electrode is in contact with the foaming film a of the second bonding material layer 7. The structure formed after the chip 4 is attached is as follows: Figure 7 shown.

[0099] Preferably, when the chip 4 is attached to the accommodating cavity 1a of the second substrate 6, the electrode side of the chip 4 can be oriented toward the side away from the second bonding material layer 7, that is, the electrode of the chip 4 faces downward, so that the foaming film a of the second bonding material layer 7 does not contact the chip 4 electrode, but contacts the back of the chip 4, which can prevent the chip 4 electrode surface from being contaminated, causing contamination and causing contaminants to be buried in the substrate to form serious reliability problems. It should be noted here that the chip 4 in the accommodating cavity 1a of the first substrate 1 and the chip 4 in the accommodating cavity 1a of the second substrate 6 can be arranged in opposite directions to be symmetrically arranged relative to the support plate 3. That is, the back of the chip 4 in the accommodating cavity 1a of the first substrate 1 contacts the first bonding material layer 2, and the back of the chip 4 in the accommodating cavity 1a of the second substrate 6 contacts the second bonding material layer 7. Alternatively, the surface of the chip 4 has a protective film to prevent the chip 4 electrode surface from being contaminated. After debonding, the protective film on the surface of the chip 4 can be removed. The protective film can be a film of copper foil or other materials.

[0100] S7: Second pressing and filling with resin, pressing and filling with resin on the second surface of the second substrate 6 to form a second resin layer 8;

[0101] That is, the second surface of the second substrate 6 is pressed and filled with resin, and the filled resin forms a second resin layer 8. In this embodiment, the second surface of the second substrate 6 can be the lower surface of the second substrate 6. The second surface of the second substrate 6 is pressed and filled with resin, and specifically, a vacuum laminator can be used to press the resin on the second surface of the second substrate 6. During the pressing and filling of the resin, the resin fills the gaps between the circuits on the surface of the second substrate 6 and the gaps around the chip 4. The structure formed after the second pressing and filling of the resin step is as follows: Figure 8 It is worth noting that no pre-curing is performed in the first pressing and embedding resin step and the second pressing and embedding resin step.

[0102] The surface of the second resin layer 8 may be provided with a protective film, which may be removed before or after the blind hole 9 processing step. The protective film may prevent the second resin layer 8 from being contaminated.

[0103] An ABF (Ajinomoto Buildup Film) resin sheet can also be used in this second resin lamination and embedding step. In this second resin lamination and embedding step, the OPP film of the ABF resin sheet is removed, and the first side of the ABF resin sheet is laminated to the second side of the second substrate 6 to form a second resin layer 8. The PET film d remains on the side of the second resin layer 8 facing away from the second substrate 6. Specifically, in this step, the OPP film of the ABF resin sheet is removed, while the PET film d remains. The ABF resin sheet, with the OPP film removed, is laminated to the second side of the second substrate 6.

[0104] In this way, the PET film d can protect the ABF layer, and the PET film d can be torn off before or after processing the blind hole 9. The process of laminating the second resin layer 8 is also carried out in a vacuum laminator, which will not be described in detail here.

[0105] In this step, the resin can be specifically selected from the ABF resin sheet of model GXT31. Of course, the resin can also be a semi-cured PP sheet or a copper-clad resin sheet RCC, which is not limited here.

[0106] S8: First pre-curing, curing the resin in the structure formed in the previous step to more than 50%;

[0107] After the first resin layer 5 and the second resin layer 8 are pressed and buried, the first pre-curing is performed. That is, after the first resin layer 5 is pressed and buried, the pre-curing is not performed before the second resin layer 8 is pressed and buried.

[0108] Specifically, the resin in the structure formed in the previous step is cured to a degree of cure of at least 50%, or in other words, the resin in the structure formed in the previous step is cured to a degree of cure of at least 50%, thereby hardening the resin and improving its rigidity and resistance to mechanical impact. The resin in the structure formed in this step can be cured to 50%, 60%, 70%, or other degrees, but the first pre-curing step can be a low-temperature thermal cure, curing the first resin layer 5 and the second resin layer 8 to a certain degree, but not completely. No pre-curing treatment is performed prior to this step.

[0109] S9: Processing blind holes 9: opening blind holes 9 on the upper and lower surfaces of the structure formed in the previous step;

[0110] That is, blind holes 9 are opened on the upper and lower surfaces of the structure formed in the step before the blind hole 9 processing step. In this embodiment, blind holes 9 are opened on the surfaces of the first resin layer 5 and the second resin layer 8 so that the circuits covered by the first resin layer 5 and the second resin layer 8 are electrically connected to other circuits through the blind holes 9. Specifically, the blind holes 9 can be opened by laser drilling. The structure formed after the blind hole 9 processing step is as follows: Figure 9 shown.

[0111] S10: Circuit fabrication, processing circuits on the upper and lower surfaces of the structure formed in the previous step;

[0112] Specifically, the circuit is processed on the surface of the structure formed by the blind hole 9 to form the inner layer circuit 10. In this embodiment, the circuit can be processed on the surface of the first resin layer 5 and the second resin layer 8, and the inner layer circuit 10 is electrically connected to the circuit covered by the first resin layer 5 and the second resin layer 8 through the blind hole 9. The structure formed after the circuit production step is as shown in FIG. Figure 11 shown.

[0113] S11: resin insulation layer processing, providing a resin insulation layer on both the upper and lower surfaces of the structure formed in the previous step, and performing pre-curing to cure the resin insulation layer formed in this step to more than 50%;

[0114] That is, resin is pressed and embedded on the upper and lower surfaces of the structure formed in the previous step to form a resin insulation layer on the upper and lower surfaces of the structure formed in the circuit production step. The resin fills the gaps between the circuits formed in the circuit production step. The resin insulation layer formed in this step covers the inner layer circuit 10 formed in the circuit production step and partially contacts the first resin layer 5 or the second resin layer 8. Pre-curing is also performed to cure the resin insulation layer formed in this step to more than 50%, or in other words, to cure the resin in the structure formed in this step to a degree of cure of more than 50%, so as to harden the resin and improve the resin's rigidity and resistance to mechanical impact. The resin in the structure formed in this step can be cured to 50%, 60%, 70%, etc. This pre-curing is called the second pre-curing. The second pre-curing can be low-temperature thermal curing, so that the resin in the formed structure is cured to a certain degree, but not completely cured.

[0115] An ABF resin sheet can also be used for the resin insulation layer. During the resin insulation layer processing, the OPP film of the ABF resin sheet is removed, and the first side of the ABF resin sheet is pressed against the upper and lower surfaces of the structure formed in the previous step and pre-cured. A PET film d is retained on the side of the resin insulation layer facing away from the support plate 3 to protect the resin insulation layer from contamination.

[0116] In this step, the insulating layer resin can be specifically selected from the ABF resin sheet of model GXT31. Of course, the resin can also be a semi-cured PP sheet or a copper-clad resin sheet RCC, which is not limited here.

[0117] S12: manufacturing an intermediate circuit, repeating the blind hole 9 processing, circuit manufacturing and resin insulation layer processing steps N times, N ≥ 0, to form an N-layer intermediate circuit 11, and no pre-curing is performed in the N-th resin insulation layer processing step, and pre-curing is performed after copper foil is pressed on the surface of the resin insulation layer formed in the N-th resin insulation layer processing step, so that the resin insulation layer in the formed structure is cured to more than 50%;

[0118] The steps of processing the blind via 9, fabricating the circuit, and processing the resin insulation layer are repeated N times, where N ≥ 0. When N > 0, N layers of intermediate circuit 11 can be processed in this step. When N = 0, the outer layer circuit 13 is processed directly. That is, each time the steps of processing the blind via 9, fabricating the circuit, and processing the resin insulation layer are repeated, one layer of intermediate circuit 11 is processed. The method for manufacturing a board-level fan-out packaging structure provided in this application can process substrates of any number of layers, and is not limited to odd or even layers.

[0119] The key point of this embodiment is that, with the exception of the Nth resin insulation layer processing step, each subsequent resin insulation layer processing step undergoes a pre-curing step after the resin insulation layer is applied to the circuit surface, and the curing is incomplete. Furthermore, during the intermediate circuit manufacturing process, the support plate is symmetrically processed with identical wiring layers and insulation layers on both sides. This results in a symmetrical stress distribution throughout the temporary sandwich bonding structure, resulting in extremely low warpage during multi-layer wiring processing, eliminating the issue of inability to process due to fundamental warpage.

[0120] Furthermore, after the copper foil is pressed onto the surface of the resin insulation layer formed in the Nth resin insulation layer processing step, pre-curing is performed to cure the resin insulation layer in the formed structure to more than 50%.

[0121] Specifically, copper foil is laminated on the surface of the outermost resin insulating layer in the structure formed in the intermediate circuit manufacturing step. In this embodiment, copper foil can be laminated on the upper and lower surfaces of the structure formed in the intermediate circuit manufacturing step. It should be noted that if the surface of the outermost resin layer in the structure formed in the previous step has a PET film, the PET film is removed and then the copper foil is laminated, and then pre-curing is performed to cure the resin insulating layer in the structure to more than 50%. The structure formed after the copper foil lamination step is as follows: Figure 12 shown.

[0122] Alternatively, the resin insulation layer and the copper foil may be pressed together in the Nth resin insulation layer processing step, that is, when the last resin insulation layer is pressed, the last resin insulation layer and the copper foil are pressed together.

[0123] It should be noted that in the intermediate circuit manufacturing step S12, no pre-curing is performed after laminating the resin insulation layer in the final resin insulation layer process, or pre-curing may not be performed in the Nth resin insulation layer process. That is, after the resin insulation layer is laminated, the copper foil is directly laminated, and then pre-curing is performed. In the intermediate circuit manufacturing step S12, except for the final resin insulation layer process, pre-curing is performed after laminating the resin insulation layer in the remaining N-1 resin insulation layer processing steps.

[0124] S13: Debonding, debonding the first bonding material layer 2 from the first surface of the first substrate 1, and debonding the second bonding material layer 7 from the first surface of the second substrate 6;

[0125] The first bonding material layer 2 is separated from the first surface of the first substrate 1, and the first substrate 1 and the first bonding material layer 2 are debonded. Figure 13As shown. The second bonding material layer 7 is separated from the first surface of the second substrate 6. Specifically, the structure formed in the previous step can be heated to the debonding temperature of the first bonding material layer 2 and the second bonding material layer 7 and maintained for 1 minute to 3 minutes to achieve debonding. Therefore, the first bonding material layer 2 and the second bonding material layer 7 can be the same so that the debonding temperatures of the first bonding material layer 2 and the second bonding material layer 7 are the same.

[0126] S14: third pressing and filling resin, pressing and filling resin on the first surface of the first substrate 1 and pressing copper foil on the surface of the formed resin layer to obtain a first temporary structure, pressing and filling resin on the first surface of the second substrate 6 and pressing copper foil on the surface of the formed resin layer to obtain a second temporary structure;

[0127] That is, the resin is pressed and filled on the first surface of the first substrate 1, and the third resin layer 12 of the first substrate 1 is formed. Specifically, a vacuum laminator can be used to press the resin on the first surface of the first substrate 1. During the pressing and filling process of the resin, the resin fills the gaps between the circuits on the surface of the first substrate 1 and the gaps around the chip 4. After the resin is pressed and filled on the first surface of the first substrate 1, copper foil is pressed on the surface of the formed resin layer, that is, copper foil is pressed on the surface of the third resin layer 12. The structure formed after the resin and copper foil are pressed and filled on the first surface of the first substrate 1 is as follows. Figure 14 As shown, this structure is a first temporary structure.

[0128] A resin is laminated onto the first surface of the second substrate 6 to form a resin insulation layer. Specifically, a vacuum laminator can be used to laminate the resin onto the first surface of the second substrate 6. During this lamination process, the resin fills the gaps between the circuits on the surface of the second substrate 6 and the gaps around the chip 4. After the resin is laminated onto the first surface of the second substrate 6, copper foil is laminated onto the surface of the formed resin layer. The structure formed by laminating the resin and copper foil onto the first surface of the second substrate 6 is referred to as the second temporary structure.

[0129] An ABF resin sheet can also be used in the third resin lamination and embedding step. In this third resin lamination and embedding step, the OPP film of the ABF resin sheet is removed, and the first side of the ABF resin sheet is laminated to the first side of the first substrate 1 or the first side of the second substrate 6. In the first temporary structure, the PET film d is removed from the side of the resin insulation layer formed in the third resin lamination and embedding step facing away from the first substrate 1, and then copper foil is laminated. In the second temporary structure, the PET film d is removed from the side of the resin insulation layer formed in the third resin lamination and embedding step facing away from the second substrate 6, and then copper foil is laminated.

[0130] The resin used in this step can be a GXT31 ABF resin sheet. Alternatively, a pre-cured PP sheet or a copper-clad RCC resin sheet can be used, without limitation. However, the resin material used for lamination on both the first and second surfaces of the same substrate should be the same to prevent severe substrate warping.

[0131] S15: Second pre-curing, curing the resin in the first temporary structure and the second temporary structure to more than 50%;

[0132] Specifically, the first temporary structure and the second temporary structure are cured at a low temperature, so that the resins in the first temporary structure and the second temporary structure are cured to more than 50%.

[0133] The second pre-curing step may specifically involve curing the resin in the structure formed in this step to 50%-70%. Specifically, the degree of curing of the resin after the second pre-curing step may be 50%, 60%, 70%, etc., to harden the resin and improve its rigidity and resistance to mechanical impact. Preferably, the resin in the structure formed is cured to 70%.

[0134] Alternatively, the second pre-curing step specifically involves placing the formed structure in a constant temperature environment of 130°C to 155°C for 30 to 60 minutes to pre-cure the resin in the structure. Specifically, the formed structure can be placed in a constant temperature environment of 130°C, 135°C, 140°C, or 150°C for 25 minutes, 30 minutes, or 35 minutes. Preferably, the formed structure is placed in a constant temperature environment of 150°C for 30 to 60 minutes.

[0135] S16: The structure formed in the previous step is placed in a laminator, clamped by a mirror steel plate, under a preset vacuum degree and a preset pressure, so that the resin in the structure is cured to more than 90%;

[0136] High temperature curing can be used in this step. After this step is completed, the resin in the first temporary structure and the second temporary structure can be cured to more than 90%, that is, the degree of curing is more than 90%.

[0137] Specifically, the first temporary structure and the second temporary structure can be placed in a laminator, clamped by a mirror steel plate, in a constant temperature environment of 190°C-210°C to cure the resin in the structure to more than 90%. For example, the structure formed by circuit production can be placed in a constant temperature environment of 190°C, 195°C, 200°C, 205°C or 210°C to cure the resin in the structure to more than 90% or completely cured. Preferably, the structure formed by circuit production is placed in a constant temperature environment of 190°C-210°C, and at the same time, the environmental vacuum degree can be maintained at 1Pa-15Pa for 50min-70min. The preset vacuum degree is 1Pa-15Pa, and the preset pressure is 0.1MPa-0.5MPa. For example, the structure formed by circuit production is placed in a constant temperature environment of 200°C, while maintaining the environmental vacuum degree of 10Pa and the pressure of 0.5Mpa for 60min.

[0138] In this step, a laminator can be used, with two mirror steel plates respectively clamping the first temporary structure or the second temporary structure until the step is completed. It should be noted that in this application, all pre-curing and curing steps can be performed in an oven.

[0139] S17: making an outer layer circuit, performing blind hole 9 processing and circuit making steps on the cured structure to form an outer layer circuit 13;

[0140] On the first temporary structure and the second temporary structure after solidification, blind holes 9 are processed and circuits are made to form an outer layer circuit 13. That is, blind holes 9 are opened again on the surface of the structure and circuits are made to form an outer layer circuit 13. The outer layer circuit 13 is electrically connected to the internal circuit through the blind holes 9. After this step, the structure formed after the blind holes 9 are processed is as follows: Figure 15 As shown, after blind hole processing, the surface copper foil is corroded and removed; the structure formed after circuit production is as follows Figure 16 shown.

[0141] S18: Make a solder resist layer, and make a solder resist layer 14 on the surface of the outer layer circuit 13; the structure formed after the step of making the solder resist layer 14 is as follows Figure 17 shown.

[0142] S19: coating the surface of the structure formed after forming the solder resist layer 14. The coating may be made of NiPdAu (nickel palladium gold), NiAu (nickel gold), Sn (tin), or OSP (Organic Solderability Preservatives).

[0143] In this application, since the circuits are arranged on both sides of the substrate and interconnected, this provides advantages for subsequent POP (Package-on-Package) interconnection in board-level fan-out packaging. This avoids the subsequent step of manufacturing through-hole conductive vias. By leveraging the substrate's existing through-hole processing and mature manufacturing processes, the use of high-aspect-ratio plate copper pillar manufacturing technology is avoided, reducing processing difficulty. Furthermore, during the intermediate circuit manufacturing process, the support plate is symmetrically processed with identical wiring layers and insulation layers on both sides. Therefore, the entire sandwich temporary bonding structure has a symmetrical stress distribution, resulting in extremely low warpage during multi-layer wiring processing, and preventing problems with processing due to basic warpage. Furthermore, the first pre-curing step is performed only after the first and second press-fit resin embedding steps are completed. Each pre-curing step is performed after processing a layer of intermediate circuit 11 and providing a resin insulation layer on the circuit surface. Pre-curing is performed, and the curing is incomplete until all the resin is press-fitted and embedded, and a final curing step is performed to cure the resin in the structure to over 90%. The resin in the board-level fan-out packaging structure is in a semi-cured state before curing. At this time, the modulus of the resin material in the board-level fan-out packaging structure is low, and the substrate is in a low-stress and low-warping state. In this way, the process of attaching the chip 4, forming the first resin layer 5 and the second resin layer 8, making the intermediate circuit 11 to the third pressing and filling resin is completed in a low-warping state, avoiding warping and excessive bending of the substrate during the processing of the board-level fan-out packaging structure, and thus avoiding structural cracking and delamination.

[0144] In addition, in the manufacturing method of the board-level fan-out packaging structure of the present application, a first bonding material layer 2 and a first substrate 1 are arranged on one side of the support plate 3, and a second bonding material layer 7 and a second substrate 6 are arranged on the other side of the support plate 3, that is, the processing structures on both sides of the support plate 3 are symmetrically arranged, which fully utilizes the supporting function of the support plate 3 and processes two board-level fan-out packaging structures at the same time, thereby improving the manufacturing efficiency and reducing the processing cost.

[0145] In a preferred embodiment, the first pre-curing step specifically involves curing the resin in the structure formed in this step to 50%-70%. That is, the resin curing degree after the first pre-curing step is 50%-70%. Specifically, the resin curing degree after the first pre-curing step can be 50%, 60%, 70%, etc., to harden the resin and improve its rigidity and mechanical impact resistance. Preferably, the resin in the formed structure is cured to 70%.

[0146] Alternatively, the first pre-curing step specifically involves placing the formed structure in a constant temperature environment of 130° C. to 155° C. for 30 to 60 minutes to pre-cure the resin in the structure. Specifically, the formed structure can be placed in a constant temperature environment of 130° C., 135° C., 140° C., or 150° C. for 25 minutes, 30 minutes, or 35 minutes. Preferably, the formed structure is placed in a constant temperature environment of 150° C. for 30 to 60 minutes.

[0147] The pre-curing step in step S11 of processing the resin insulation layer specifically involves curing the resin in the structure formed in this step to 50%-70%. That is, the curing degree of the resin after curing in step S11 is 50%-70%. Specifically, the curing degree of the resin insulation layer formed in this step can be 50%, 60%, 70%, 75%, etc., to harden the resin and improve its rigidity and resistance to mechanical impact. Preferably, the resin in the formed structure is cured to 70%.

[0148] Alternatively, the pre-curing in the resin insulation layer processing step S11 is specifically performed by placing the formed structure in a constant temperature environment of 130°C to 155°C for 30 to 60 minutes to pre-cur the resin in the structure. Specifically, the formed structure can be placed in a constant temperature environment of 130°C, 135°C, 140°C, or 150°C for 25 minutes, 30 minutes, or 35 minutes. Preferably, the formed structure is placed in a constant temperature environment of 150°C for 30 to 60 minutes.

[0149] Of course, specific parameters of the first pre-curing and the pre-curing in the resin insulation layer processing step S11 can also be adjusted according to actual conditions, and are not specifically limited here.

[0150] In another embodiment, when the raw materials used in the first pressing and embedding resin step and the second pressing and embedding resin step are both ABF resin sheets, step S17 further includes step S17' before manufacturing the outer layer circuit: etching the copper foil to remove the copper foil on the surface of the structure formed in the previous step to facilitate subsequent circuit processing.

[0151] As an optional embodiment, step S13' is further performed after step S13: cleaning the first surface of the first substrate 1 and the first surface of the second substrate 6. This can prevent resin residue from forming on the first surface of the first substrate 1 and the first surface of the second substrate 6. Specifically, a plasma cleaner can be used for cleaning, for example, in a degumming tank at 70°C-85°C for 2-5 minutes. Other cleaning methods, such as ultrasonic alkaline cleaning, are also possible, and are not limited here.

[0152] As an optional embodiment, the curing temperature of the first pre-curing and the curing temperature of the pre-curing in the resin insulation layer processing step are lower than the debonding temperature of the first bonding material layer 2 and the second bonding material layer 7. In this way, it can be ensured that when the first pre-curing and the pre-curing in the resin insulation layer processing step are performed, the first bonding material layer 2 is still bonded to the first substrate 1, and the second bonding material layer 7 is still bonded to the second substrate 6. Specifically, the curing temperature of the first pre-curing and the curing temperature of the pre-curing in the resin insulation layer processing step can be more than 10°C lower than the debonding temperature of the first bonding material layer 2 and the second bonding material layer 7. Preferably, the curing temperature of the first pre-curing and the curing temperature of the pre-curing in the resin insulation layer processing step can be 20°C lower than the debonding temperature of the first bonding material layer 2 and the second bonding material layer 7.

[0153] In the description of the above embodiments, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0154] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for manufacturing a board-level fan-out packaging structure, characterized in that: include: Substrate windowing: cavities for accommodating chips are opened on multiple substrates, and circuits are arranged on both the front and back sides of the substrates and the circuits on the front and back sides are interconnected; A first temporary bonding step is performed to bond the first surface of the first substrate having the accommodating cavity to the first bonding material layer, wherein a support plate is fixed to a side of the first bonding material layer facing away from the first substrate; A first chip mounting step is to place the chip in the receiving cavity of the first substrate; a first pressing and filling resin, pressing and filling the resin on the second surface of the first substrate to form a first resin layer; Second temporary bonding: providing a second bonding material layer on a side of the support plate away from the first bonding material layer, and bonding the second bonding material layer to the first surface of the second substrate having the accommodating cavity; A second chip mounting step is to place the chip in the receiving cavity of the second substrate; a second pressing and filling resin, pressing and filling the second surface of the second substrate with resin to form a second resin layer; The first pre-curing cures the resin in the structure formed in the previous step to more than 50%; Blind hole processing: opening blind holes on the upper and lower surfaces of the structure formed in the previous step; Circuit fabrication: processing circuits on the upper and lower surfaces of the structure formed in the previous step; Resin insulation layer processing, providing a resin insulation layer on both the upper and lower surfaces of the structure formed in the previous step, and performing pre-curing to cure the resin insulation layer formed in this step to more than 50%; Fabricating an intermediate circuit, repeating N times of blind hole processing, circuit fabrication, and resin insulation layer processing steps, where N is greater than or equal to 0, to form N layers of intermediate circuits, without pre-curing in the Nth resin insulation layer processing step, and pre-curing after laminating copper foil on the surface of the resin insulation layer formed in the Nth resin insulation layer processing step, so that the resin insulation layer in the formed structure is cured to more than 50%; Debonding: debonding the first bonding material layer from the first surface of the first substrate, and debonding the second bonding material layer from the first surface of the second substrate; a third pressing and embedding resin, pressing and embedding resin on the first surface of the first substrate and pressing copper foil on the surface of the formed resin layer to obtain a first temporary structure, and pressing and embedding resin on the first surface of the second substrate and pressing copper foil on the surface of the formed resin layer to obtain a second temporary structure; The second pre-curing cures the resin in the first temporary structure and the second temporary structure to more than 50%; Curing: the structure formed in the previous step is placed in a laminator, clamped by mirror steel plates, under a preset vacuum degree and preset pressure, so that the resin in the structure is cured to more than 90%; Fabricating the outer layer circuit, performing blind hole processing and circuit fabrication steps on the cured structure to form the outer layer circuit; Making a solder resist layer, and making a solder resist layer on the surface of the outer layer circuit; A coating is applied to the surface of the structure formed after the solder resist layer is formed.

2. The method for manufacturing a board-level fan-out packaging structure according to claim 1, wherein: The first bonding material layer includes a foaming film, a support film, and a pressure-sensitive adhesive film stacked in sequence, wherein the foaming film of the first bonding material layer is bonded to the first surface of the first substrate, and the pressure-sensitive adhesive film of the first bonding material layer is bonded to the support plate; and / or, The second bonding material layer includes a foaming film, a support film and a pressure-sensitive adhesive film stacked in sequence, and the foaming film of the second bonding material layer is bonded to the first surface of the second substrate, and the pressure-sensitive adhesive film of the second bonding material layer is bonded to the side of the support plate facing away from the first bonding material layer.

3. The method for manufacturing a board-level fan-out packaging structure according to claim 1, wherein: The first pre-curing is specifically: curing the resin in the structure formed in this step to 50%-70%; or, the first pre-curing is specifically: placing the formed structure in a constant temperature environment of 130°C-155°C for 30min-60min to pre-cure the resin in the structure.

4. The method for manufacturing a board-level fan-out packaging structure according to claim 1, wherein: The pre-curing in the resin insulation layer processing step is specifically: curing the resin insulation layer in the structure to a degree of 50%-70%; or the pre-curing in the resin insulation layer processing step is specifically: placing the formed structure in a constant temperature environment of 130°C-155°C and maintaining it for 30min-60min to pre-cure the resin in the structure.

5. The method for manufacturing a board-level fan-out packaging structure according to claim 1, wherein: The curing is specifically as follows: placing the formed structure in a laminator, clamping it between two mirror steel plates with a pressure of 0.1MPa-0.5MPa, in an environment with a constant temperature of 190℃-210℃ and a vacuum degree of 1Pa-15Pa, and maintaining it for 50min-70min to cure the resin in the structure.

6. The method for manufacturing a board-level fan-out packaging structure according to claim 1, wherein: The raw materials used in the first pressing and filling resin step, the second pressing and filling resin step, the resin insulation layer processing step and the third pressing and filling resin step are all ABF resin sheets, and the ABF resin sheet includes an ABF main layer, an OPP film attached to the first side of the ABF main layer and a PET film attached to the second side of the ABF main layer.

7. The method for manufacturing a board-level fan-out packaging structure according to claim 6, wherein: The first resin embedding step comprises: removing the OPP film of the ABF resin sheet, and laminating the first side of the ABF resin sheet to the second surface of the first substrate to form a first resin layer, wherein the PET film remains on the side of the first resin layer facing away from the first substrate; The second resin embedding step is specifically to remove the OPP film of the ABF resin sheet and to press the first side of the ABF resin sheet onto the second surface of the second substrate to form a second resin layer, with the PET film remaining on the side of the second resin layer facing away from the second substrate.

8. The method for manufacturing a board-level fan-out packaging structure according to claim 1, wherein: Before making the outer layer circuit, the method further comprises the steps of: etching the copper foil to remove the copper foil on the surface of the structure formed in the previous step.

9. The method for manufacturing a board-level fan-out packaging structure according to any one of claims 1 to 8, wherein: After the debonding step, the method further includes cleaning the first surface of the first substrate and the first surface of the second substrate.

10. The method for manufacturing a board-level fan-out packaging structure according to any one of claims 1 to 8, wherein: The curing temperature of the first pre-curing and the curing temperature of the pre-curing in the resin insulation layer processing step are lower than the debonding temperatures of the first bonding material layer and the second bonding material layer.

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