Blind buried hole circuit board manufacturing method and circuit board

Abstract

The invention discloses a blind buried hole circuit board manufacturing method and a circuit board, and belongs to the field of circuit boards. According to the manufacturing method, blind buried holes are optimized from a concentric design to a stepped dislocation design; the method comprises the following steps: firstly, preparing a core board with buried holes, and finishing first pattern transfer before lamination, so that the accuracy of circuit design is ensured; and then the position of the blind hole is positioned by horizontally shifting the buried hole by the preset distance, so that the processing problem caused by direct superposition of the blind hole and the buried hole in the traditional concentric design is avoided, and particularly, the problems of non-uniformity of an electroplated layer and difficulty in etching are reduced under the condition that the substrate is thin and circuits are dense. According to the method, on the premise of not influencing the quality of the buried hole, the processing parameters of the blind hole, including chemical etching, copper deposition, electroplating and the like, are independently controlled, so that the stability and the consistency of the quality of the blind hole are ensured; finally, through semi-finished product processing, the method can produce the blind buried hole circuit board with high yield and stable quality, and overcomes the production problems caused by thin substrate and dense circuit in the traditional process.

Description

Technical Field

[0001] The invention belongs to the technical field of circuit boards, and in particular relates to a method for manufacturing a blind-buried via circuit board and a circuit board. Background Art

[0002] As electronic products develop towards being light, thin, short and small, the layout density of electronic components becomes higher, and the hole and line density of the circuit board carrying electronic components is also getting higher and higher. Therefore, blind buried via technology has emerged. Blind buried via technology forms blind holes or buried holes in the inner layer to achieve signal transmission without penetrating the entire PCB board, thereby saving valuable wiring space; this enables more signal lines to be routed in a limited space, improving wiring density and design freedom. Blind buried vias have been widely used in the design of modern electronic products and provide strong support for the development of electronic products.

[0003] At present, in the field of blind and buried vias, there is a type of product that adopts the design of blind via drilling on buried vias, and the blind vias and buried vias are concentrically designed, which greatly increases the manufacturing complexity. When the substrate is thin, that is, it is impossible to mechanically reduce copper, and the circuit is dense, the product yield will be very low or even unable to be produced; the reasons for the above problems are mainly reflected in: after the buried via processing, copper plating treatment is required above the buried via to form a copper barrier layer; the copper barrier layer of the laser drilled blind via requires a certain thickness, and the thin substrate basically cannot reduce copper. When the line width and line spacing reach below a certain thickness, the uneven electroplating layer will make etching difficult, resulting in low yield; and the requirements for laser equipment are high. When the copper layer is thin, it is easy to penetrate the copper layer on the resin, causing the diameter-to-depth ratio of the hole to exceed the maximum capacity of the filling electroplating, and the electroplating filling cannot be achieved, resulting in a large scrap of the BGA depression, and the normal production of the product cannot be guaranteed.

[0004] It can be seen that the existing blind and buried via circuit board manufacturing method, due to the concentric design of the blind via and the buried via, leads to a mismatch between the diameter-to-depth ratio of the blind via caused by high-energy laser drilling and the filling and plating process, making it impossible to achieve electroplating filling, resulting in a large-scale scrap of the BGA depression. Summary of the invention

[0005] The present invention provides a method for manufacturing a blind and buried via circuit board and a circuit board, so as to solve the technical problem that the blind hole and the buried hole are concentrically designed, resulting in a mismatch between the diameter-to-depth ratio of the blind hole caused by high-energy laser drilling and the filling and plating process, thereby failing to achieve electroplating and leveling.

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

[0007] A method for manufacturing a blind buried via circuit board comprises the following steps:

[0008] S1: drilling, copper deposition, and electroplating the double-copper core board in sequence to obtain a core board with buried holes;

[0009] S2: performing a first pattern transfer process on both sides of the core board with buried holes to obtain a core board to be pressed;

[0010] S3: pressing the outer core board and the core board to be pressed together to obtain a pressed board;

[0011] S4: offset the buried hole by a preset distance in the horizontal direction, and perform a second pattern transfer process on the copper foil surface of the laminated board to locate the opening position of the blind hole; perform chemical etching, copper deposition and electroplating on the opening position of the blind hole in sequence to obtain a core board with blind buried holes;

[0012] S5: Processing the core board with blind and buried vias as semi-finished products to obtain a blind and buried via circuit board.

[0013] Furthermore, in S1, the double copper surface core board is subjected to drilling, copper deposition, and electroplating treatments in sequence; wherein, the double copper surface core board after copper deposition is electroplated using a VCP process.

[0014] Furthermore, in S1, after the electroplating treatment, the double copper-sided core board after the electroplating treatment is subjected to resin plugging and grinding treatment to obtain a core board with buried holes.

[0015] Furthermore, in S2, after the first pattern transfer process is performed, the core board with buried holes after the first pattern transfer process is etched and browned to obtain a core board to be pressed.

[0016] Furthermore, in S3, the outer core board is made of resin copper.

[0017] Further, in S4, the preset distance of the offset buried via is 0.25-0.35 mm.

[0018] Furthermore, in S4, the specific steps of performing a second pattern transfer process on the copper foil surface of the laminate include:

[0019] The copper foil surface of the laminate is subjected to a second pattern transfer process using the LDI pattern transfer process to locate the opening position of the blind hole;

[0020] The DES process is used to etch the copper foil corresponding to the blind hole opening position to expose the corresponding epoxy resin glue under the copper foil.

[0021] Furthermore, in S4, the specific steps of sequentially performing chemical etching, copper deposition and electroplating on the blind hole opening position include:

[0022] The epoxy resin glue corresponding to the bottom of the copper foil is etched with 92% to 98% concentrated sulfuric acid to obtain a core board with blind holes;

[0023] The core board with blind holes is subjected to copper deposition and VCP hole filling electroplating in sequence to obtain a core board with blind buried holes.

[0024] Furthermore, in S5, the specific steps of processing the semi-finished product of the core board with blind buried holes include:

[0025] For the core board with blind and buried vias, DES, AOI, solder mask, surface treatment, molding, testing and appearance inspection processes are carried out in sequence.

[0026] A blind buried via circuit board is manufactured by adopting the blind buried via circuit board manufacturing method.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The present invention provides a method for manufacturing a blind buried hole circuit board, which optimizes the blind buried hole from concentric to stepped staggered design; first, a core board with buried holes is prepared, and the first graphic transfer is completed before lamination to ensure the accuracy of the circuit design; then, the blind hole position is located by horizontally offsetting the buried hole by a preset distance, thereby avoiding the processing difficulties caused by the direct superposition of the blind hole and the buried hole in the traditional concentric design, and ensuring the effect of electroplating and filling; especially in the case of thin substrates and dense circuits, the problems of uneven electroplating and difficult etching are reduced. Under the premise of not affecting the quality of the buried hole, the method independently controls the processing parameters of the blind hole, including chemical etching, copper deposition and electroplating, thereby ensuring the stability and consistency of the quality of the blind hole; finally, through the processing of semi-finished products, the method can produce a blind buried hole circuit board with high yield and stable quality, overcoming the production difficulties caused by thin substrates and dense circuits in traditional processes, and providing a more efficient and reliable solution for the manufacture of blind buried hole circuit boards.

[0029] In addition, since the present method does not need to perform copper plating above the buried hole, the present method can also reduce one copper plating and simplify the process flow; at the same time, the copper foil thickness of the inner buried hole layer is reduced, which is beneficial to improving the yield rate of fine circuit etching; the blind buried hole step staggered design is adopted to thicken the copper foil thickness at the bottom of the blind hole, which can effectively avoid the mismatch between the blind hole diameter-to-depth ratio caused by high-energy laser penetration and the filling and plating process.

[0030] Preferably, in the present invention, the VCP process is used to electroplate the double-copper core board after copper deposition. The VCP (vertical continuous plating) process can provide a more uniform and denser electroplating layer, effectively solving the problem of uneven plating that may occur in traditional electroplating, and improving the quality and yield of the product.

[0031] Preferably, in the present invention, the double-copper core board after electroplating is subjected to resin plugging and grinding treatment. The resin plugging can fill the holes after drilling, which can effectively prevent the resin glue from being unable to fill the via holes during the lamination process, resulting in residual voids, and the phenomenon of layered bulging due to air expansion during subsequent reflow soldering; the grinding treatment ensures the flatness of the core board surface, providing a good foundation for subsequent graphic transfer and lamination.

[0032] Preferably, in the present invention, the core board with buried holes after the first pattern transfer process is etched and browned. The etching process can accurately remove unnecessary copper foil parts to form the required circuit pattern; the browning process enhances the bonding force between the copper foil and the resin, and improves the stability of the circuit board after lamination.

[0033] Preferably, in the present invention, the outer core board adopts resin copper skin, that is, RCC (copper foil with glue). Compared with the traditional semi-cured sheet, that is, the PP glue contains glass fiber, the glass fiber cannot be bitten off, and the copper foil with glue does not contain glass fiber, which is a prerequisite for the subsequent sulfuric acid biting, ensuring the glue removal effect.

[0034] Preferably, in the present invention, the preset distance of the offset buried hole is 0.25mm to 0.35mm, and the position of the blind hole is located by horizontally offsetting the preset distance of the buried hole, which effectively avoids the processing difficulties caused by the direct superposition of the blind hole and the buried hole, reduces the manufacturing complexity, and improves the production efficiency and product yield.

[0035] Preferably, in the present invention, LDI (laser direct imaging) technology is used to improve the accuracy and efficiency of pattern transfer; DES (development, etching and stripping) process ensures the accuracy of the blind hole opening position, providing a reliable basis for subsequent processing.

[0036] Preferably, in the present invention, concentrated sulfuric acid is used for chemical etching, which can efficiently and accurately remove the epoxy resin glue to form a blind hole; the method of removing the epoxy resin glue with concentrated sulfuric acid replaces the traditional laser drilling of blind holes, which is highly efficient and economical; the use of VCP hole filling electroplating ensures the uniformity and density of the electroplating layer inside the blind hole, thereby improving the electrical performance and reliability of the blind and buried hole circuit board.

[0037] Preferably, in the present invention, the quality control of the blind and buried via circuit boards at each production stage and the reliability of the final product are ensured through semi-finished product processing procedures such as DES, AOI (automatic optical inspection), solder mask, surface treatment, molding, testing and appearance inspection.

[0038] The present invention also provides a blind buried via circuit board, which is manufactured by the above-mentioned blind buried via circuit board manufacturing method. The blind vias and buried vias of the blind buried via circuit board adopt an offset staggered design, so that the blind buried vias of the entire circuit board have a stepped structure, which ensures good and reliable electrical performance. At the same time, due to the staggered design, it also meets the product development requirements of high-density layout. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 A flowchart of a method for manufacturing a blind and buried via circuit board provided by an embodiment of the present invention;

[0040] Figure 2 A schematic diagram of the structure of a blind buried via circuit board manufactured by a conventional blind buried via manufacturing method provided by an embodiment of the present invention;

[0041] Figure 3 A schematic structural diagram of a blind buried via circuit board manufactured using the blind buried via manufacturing method provided by an embodiment of the present invention.

[0042] Reference numerals:

[0043] 1-Buried via; 2-Blind via. DETAILED DESCRIPTION

[0044] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail in the following specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0045] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0046] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0048] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0049] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0050] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0051] A method for manufacturing a blind buried via circuit board comprises the following steps:

[0052] S1, drilling, copper deposition, and electroplating the double-copper core board in sequence to obtain a core board with buried holes;

[0053] The double copper surface core board is subjected to drilling, copper deposition and electroplating treatments in sequence; wherein, the double copper surface core board after copper deposition is electroplated by using VCP process.

[0054] After the electroplating treatment, the double copper-sided core board after the electroplating treatment is subjected to resin plugging and grinding treatment to obtain a core board with buried holes.

[0055] S2, performing a first pattern transfer process on both sides of the core board with buried holes to obtain a core board to be pressed;

[0056] After the first pattern transfer process is performed, the core board with buried holes after the first pattern transfer process is etched and browned to obtain a core board to be pressed.

[0057] S3, pressing the outer core board and the core board to be pressed together to obtain a pressed board;

[0058] The outer core plate is made of resin copper.

[0059] S4, offsetting the buried hole by a preset distance in the horizontal direction, performing a second pattern transfer process on the copper foil surface of the laminated board to locate the blind hole opening position; performing chemical etching, copper deposition and electroplating processes on the blind hole opening position in sequence to obtain a core board with blind buried holes;

[0060] The preset distance of the offset buried via is 0.25 to 0.35 mm.

[0061] The specific steps of performing a second pattern transfer process on the copper foil surface of the laminate include:

[0062] The copper foil surface of the laminate is subjected to a second pattern transfer process using the LDI pattern transfer process to locate the blind hole opening position; the copper foil corresponding to the blind hole opening position is etched using the DES process to expose the corresponding epoxy resin glue under the copper foil.

[0063] The specific steps of chemical etching, copper deposition and electroplating the blind hole opening position in sequence include:

[0064] The epoxy resin glue corresponding to the bottom of the copper foil is etched with 92% to 98% concentrated sulfuric acid to obtain a core board with blind holes; the core board with blind holes is subjected to copper deposition and VCP hole filling electroplating in sequence to obtain a core board with blind buried holes.

[0065] S5, processing the core board with blind and buried vias into semi-finished products to obtain a circuit board with blind and buried vias.

[0066] For the core board with blind and buried vias, DES, AOI, solder mask, surface treatment, molding, testing and appearance inspection processes are carried out in sequence.

[0067] Example 1

[0068] Combined with what is mentioned in the background technology, currently, in the field of blind and buried vias, there is a type of product that adopts a design in which a blind hole is drilled on a buried hole, and the blind hole and the buried hole are concentrically designed, which greatly increases the complexity of manufacturing. When the substrate is thin, that is, copper cannot be mechanically reduced, and the circuit is dense, the product yield will be very low or even unable to be produced; the reasons for the above problems are mainly reflected in: after the buried hole processing, copper plating treatment is required above the buried hole to form a copper barrier layer; the copper barrier layer of the laser drilled blind hole requires a certain thickness, and the thin substrate basically cannot reduce copper. When the line width and line spacing reach below a certain thickness, the uneven electroplating layer will make etching difficult, resulting in low yield; and the requirements for laser equipment are high. When the copper layer is thin, it is easy to penetrate the copper layer on the resin, causing the diameter-to-depth ratio of the hole to exceed the maximum capacity of the filling electroplating, and the electroplating filling cannot be achieved, resulting in a large scrap of the BGA depression, and the normal production of the product cannot be guaranteed.

[0069] For example, Figure 2As shown in the figure, in the traditional blind and buried hole production method, taking a 0.6mm four-layer board (i.e. L1~L4) as an example, the process parameters, specifications and production difficulties of the traditional production method are explained:

[0070] A 0.3mm copper-containing double-sided 18 / 18μm core board is used for cutting, drilling, copper deposition, and electroplating to 20μm in the hole (according to the deep plating capacity of 1:1, the surface copper is about 38μm) to form a buried hole 1, resin plugging and grinding are performed, copper is deposited on the resin, and the resin copper is electroplated to be thickened to more than 18μm (the surface copper is about 56μm), and pattern transfer and etching are performed. Browning and semi-cured sheet and copper foil are pressed together, the copper foil on the pressed surface is browned, and laser drilling is performed to form a blind hole 2. Finally, it goes through mechanical drilling, copper deposition, electroplating, DES, AOI, solder mask, surface treatment, molding, testing, and appearance inspection.

[0071] From the above, it can be seen that because the copper barrier layer of laser drilling requires a certain thickness, the thickness of the copper foil on the resin must reach about 18μm, and the buried hole 1 larger than two layers, its IPC secondary specification also requires the hole copper to be 20μm on average. The raw material is H / Hoz (18μm). Without considering the uniformity and positive deviation of electroplating, the surface copper foil has reached 56μm, and the thin substrate can basically not reduce copper. When the line width and line spacing reach 100 / 100μm or less, the uneven electroplating layer will make etching difficult, the yield is low, and the requirements for laser equipment are high. When the copper layer is thin, it is easy to penetrate the copper layer on the resin, causing the diameter-to-depth ratio of the hole to exceed the maximum capacity of the filling electroplating, and it cannot be filled by electroplating. It can be seen that the existing production method is not only cumbersome in process flow, but also the thick copper plating is not convenient for the production of fine lines, and the product quality cannot be guaranteed.

[0072] In order to solve the above problems, the present invention provides a method for manufacturing a blind and buried via circuit board. The method provides a blind and buried via manufacturing process, in which the blind via and the buried via are offset designed, that is, the concentric holes are split and appropriately moved to form stepped holes, which can save one time of resin plugging, copper deposition and copper electroplating treatment, simplify the process flow, save costs, and at the same time, the inner layer is plated once, which can design dense routing and facilitate the production of fine circuits.

[0073] The present invention is further described in detail below with reference to the accompanying drawings and embodiments:

[0074] like Figure 1 As shown, this embodiment provides a method for manufacturing a blind buried via circuit board. In this embodiment, Figure 3 As shown, the concentric buried vias of L2-L3 layers and the blind vias of L1-L2 are optimized from concentric to offset stepped, where the buried via 1 is 0.20 mm and the blind via 2 is 0.10 mm. Then the blind via 2 or the buried via 1 is relatively offset by 0.25 mm to 0.35 mm, and pads are added to the corresponding layers to achieve electrical performance. The specific steps are as follows:

[0075] Step 1: Cut the core board with 18 / 18 μm copper on both sides, perform drilling, copper deposition and electroplating in sequence to obtain buried via 1. After this step, a core board with buried vias is obtained;

[0076] In this embodiment, the VCP process is used to electroplate the double copper core board after copper deposition. VCP (Vertical Continuous Plating) thickening mainly refers to increasing the copper thickness in the circuit and the hole through the VCP process to achieve excellent electrical performance and mechanical strength; VCP is electroplated to 20μm in the hole, and according to the deep plating capacity of 1:1, the surface copper is about 38μm.

[0077] In this embodiment, in order to effectively prevent the resin glue from failing to fill the via holes during the lamination process, resulting in residual voids, and the phenomenon of layered bulging due to air expansion during the subsequent reflow soldering, the holes of the double-copper core board after electroplating are plugged with resin; in order to ensure the flatness of the core board surface and provide a good foundation for subsequent graphic transfer and lamination, grinding treatment is also performed.

[0078] Step 2: Perform the first pattern transfer process on both sides of the core board with buried holes, i.e., the L2 / L3 layer, and then complete the process. The etching process can accurately remove the unnecessary copper foil part to form the required circuit pattern; obtain the core board to be pressed;

[0079] In this embodiment, after etching is completed, the core board to be pressed needs to be browned, so that the bonding force between the copper foil and the resin is enhanced and the stability of the circuit board after pressing is improved.

[0080] Step 3: Use the thin copper foil RCC with adhesive to press the core board to obtain a pressed board;

[0081] In this embodiment, the glass fiber semi-cured sheet in the traditional manufacturing method is replaced by RCC (copper foil with glue) material for pressing. RCC does not contain glass fiber, which serves as a prerequisite for the subsequent sulfuric acid etching to ensure the glue removal effect.

[0082] Step 4: offset the buried hole by a preset distance in the horizontal direction. In this embodiment, the offset is 0.3 mm. The copper foil surface of the laminate is subjected to a second pattern transfer process to locate the blind hole opening position, and etching and film stripping are performed at the same time to expose the corresponding epoxy resin glue under the copper foil. Then, the blind hole opening position is subjected to chemical etching, copper deposition and electroplating in sequence, thereby obtaining a blind hole 2;

[0083] In this embodiment, the specific steps are:

[0084] The exposed epoxy resin glue is etched with 92% to 98% concentrated sulfuric acid to obtain a core board with blind holes;

[0085] The core board with blind holes is subjected to copper deposition and VCP hole filling electroplating in sequence to obtain a core board with blind buried holes.

[0086] The chemical etching method of concentrated sulfuric acid is used to remove the epoxy resin glue of the corroded copper points to make blind holes, which replaces the laser drilling blind holes. It is not only efficient but also economical.

[0087] The blind hole 2 is sandblasted and cleaned to obtain a core board with blind buried holes.

[0088] Step 5: Finally, the core board with blind and buried vias is processed into a semi-finished product to obtain a blind and buried via circuit board; in this embodiment, the specific steps of semi-finished product processing include:

[0089] Mechanical drilling, copper plating, VCP filling and electroplating, DES, AOI inspection, solder mask, surface treatment, molding, testing and appearance inspection are performed to obtain blind and buried hole circuit boards.

[0090] Among them, the DES (Develop, Etch, and Strip) process is a key process step, which mainly involves three main links: development, etching and stripping. The specific steps are as follows:

[0091] First, Development

[0092] Function: The development process mainly removes the unexposed parts of the dry film or liquid photosensitive film, leaving the photosensitive cross-linked and solidified graphic parts.

[0093] Principle: The active groups in the unexposed part of the photosensitive film react with a dilute alkaline solution (such as sodium carbonate solution) to generate soluble substances, which are then dissolved, while the exposed part remains insoluble.

[0094] Steps: dry film incoming → developing → washing (multiple times) → drying → drying with cold air → drying with hot air.

[0095] Second, Etch

[0096] Function: Chemically remove excess copper from the copper foil surface of the circuit board to form the required circuit pattern.

[0097] Principle: The copper layer without anti-etching layer is consumed by oxidation-reduction reaction (mainly acid etching) or complex reaction (mainly alkaline etching). In acid etching, cupric chloride solution is often used as etching solution, in which the divalent copper ions oxidize the copper on the board surface into monovalent copper, and then the monovalent copper is oxidized back to divalent copper by an oxidant (such as hydrogen peroxide), so as to regenerate the etching solution.

[0098] Steps: etching → water washing (multiple times) → intermediate inspection.

[0099] Third, Strip

[0100] Function: Completely remove the anti-corrosion dry film (or ink) on the board surface to expose the fresh copper surface for subsequent production processes.

[0101] Principle: Use a strong alkali (such as sodium hydroxide) solution to dissolve the polymer compounds in the dry film, thereby peeling it off the board surface.

[0102] Steps: De-mold → Wash with water (multiple times) → Dry with suction → Dry with strong air → Dry with hot air.

[0103] This embodiment provides a method for manufacturing a blind buried via circuit board, which has the following advantages over the traditional method for manufacturing a blind buried via circuit board:

[0104] First, the design of blind buried vias is optimized from concentric to staggered, which can reduce the copper plating once, is simpler in process, and reduces the copper foil thickness of the inner buried via layer, which is beneficial to improve the yield of fine circuit etching. The staggered design makes the blind via copper foil of the L2 layer thicker than that of the concentric plating layer, which can avoid the mismatch between the blind via diameter-to-depth ratio caused by high-energy laser penetration and the filling and plating process, thereby causing the undesirable phenomenon of BGA depression.

[0105] Second, the glass fiber semi-cured sheet is replaced with RCC (copper foil with glue) material for pressing, the copper points of the blind hole are etched by DES process, and then highly concentrated sulfuric acid is used to remove the epoxy resin glue of the etched copper points to make blind holes, which replaces laser drilling of blind holes, with high efficiency and good economy.

[0106] Example 2

[0107] This embodiment also provides a blind buried via circuit board, which is manufactured by the blind buried via circuit board manufacturing method mentioned in Embodiment 1. Figure 3 As shown, the specific structure is as follows:

[0108] The present embodiment provides a blind buried via circuit board, including a double copper surface core board, wherein a through hole is opened in the double copper surface core board, and the through hole is electroplated by copper deposition and VCP electroplating process to form a buried via 1 of the blind buried via circuit board; an outer core board is pressed on the top of the double copper surface core board, and the outer core board is made of RCC material; at a position 0.25mm to 0.35mm away from the buried via 1, the copper foil surface on the outer core board is sequentially subjected to LDI pattern transfer and etching treatment to remove the copper point (copper surface at the blind hole) at the position where the blind via is opened; then, 95% concentrated sulfuric acid is used to chemically etch the epoxy resin glue exposed below the copper point, and finally copper deposition and VCP electroplating are sequentially performed at the hollow position to form a blind via 2 of the blind buried via circuit board; and pads are added to the corresponding corresponding layers to form electrical connections.

[0109] This embodiment provides a blind buried via circuit board, which has the following advantages compared with the existing blind buried via circuit boards:

[0110] The blind holes and buried holes of the blind and buried hole circuit board adopt an offset staggered design, so that the blind and buried holes of the entire circuit board have a stepped structure, ensuring good and reliable electrical performance; the circuit board has the advantages of controllable manufacturing process, stable product quality, high production efficiency and good yield, and can meet the market demand for high-quality blind and buried hole circuit boards.

[0111] The present invention provides a method for manufacturing a blind and buried via circuit board and a circuit board, which has the following advantages over the traditional manufacturing method:

[0112] First, improve production yield: by offsetting the buried hole by a preset distance in the horizontal direction and then opening the blind hole, the increased manufacturing complexity and low yield caused by the concentric design of the blind hole and the buried hole are effectively avoided; especially when the substrate is thin, the circuit is dense and mechanical copper reduction is impossible, this method significantly reduces the etching difficulty caused by uneven electroplating layer, thereby improving the production yield of the product.

[0113] Second, optimize the electroplating process: Use the VCP (vertical continuous plating) process to electroplate the double-copper core board after copper deposition, as well as the subsequent VCP hole-filling electroplating process to ensure the uniformity and thickness control of the electroplating layer, further improve the electroplating effect, reduce the occurrence of defects such as BGA depression, and improve the reliability and stability of the product.

[0114] Third, fine processing control: In the process of opening blind holes, the LDI (laser direct imaging) pattern transfer process and DES (de-smearing) process are used to accurately control the position and shape of the blind holes, reducing processing errors and improving processing accuracy and efficiency; at the same time, through strict semi-finished product processing procedures (DES, AOI, solder mask, surface treatment, molding, testing and appearance inspection), the quality and performance of the final product are ensured.

[0115] Fourth, enhance equipment compatibility: This method has relatively lower requirements for laser equipment, because by offsetting the buried hole position and optimizing the electroplating process, the risk of penetrating the copper layer on the resin due to the thin copper layer is reduced, thereby reducing the accuracy and power requirements of the laser equipment.

[0116] Fifth, expand the scope of application: This method is not only applicable to the traditional blind and buried via circuit board production, but also can achieve efficient and high-quality production under complex conditions such as thin substrates and dense circuits, broadening the application field of blind and buried via circuit boards.

[0117] It can be seen that this production method significantly improves the production yield and product quality of blind buried hole circuit boards through innovative blind buried hole design and fine processing control, reduces production costs and scrap rate, and has significant economic and social benefits.

[0118] The above embodiment is only one of the implementation methods that can realize the technical solution of the present invention. The scope of protection claimed by the present invention is not limited only to this embodiment, but also includes changes, replacements and other implementation methods that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed by the present invention.

Claims

1. A method for manufacturing a blind and buried via circuit board, characterized in that: The steps include: S1: drilling, copper deposition, and electroplating the double-copper core board in sequence to obtain a core board with buried holes; S2: performing a first pattern transfer process on both sides of the core board with buried holes to obtain a core board to be pressed; S3: pressing the outer core board and the core board to be pressed together to obtain a pressed board; S4: offset the buried hole by a preset distance in the horizontal direction, and perform a second pattern transfer process on the copper foil surface of the laminated board to locate the opening position of the blind hole; perform chemical etching, copper deposition and electroplating on the opening position of the blind hole in sequence to obtain a core board with blind buried holes; S5: Processing the core board with blind and buried vias as semi-finished products to obtain a blind and buried via circuit board.

2. A method for manufacturing a blind and buried via circuit board according to claim 1, characterized in that: In S1, the double copper surface core board is subjected to drilling, copper deposition, and electroplating treatments in sequence; wherein, the double copper surface core board after copper deposition is electroplated by using a VCP process.

3. A method for manufacturing a blind and buried via circuit board according to claim 1, characterized in that: In S1, after the electroplating treatment, the double copper-sided core board after the electroplating treatment is subjected to resin plugging and grinding treatment to obtain a core board with buried holes.

4. A method for manufacturing a blind buried via circuit board according to claim 1, characterized in that: In S2, after the first pattern transfer process is performed, the core board with buried holes after the first pattern transfer process is etched and browned to obtain a core board to be pressed.

5. The method for manufacturing a blind and buried via circuit board according to claim 1, characterized in that: In S3, the outer core board is made of resin copper.

6. A method for manufacturing a blind and buried via circuit board according to claim 1, characterized in that: In S4, the preset distance of the offset buried via is 0.25-0.35 mm.

7. A method for manufacturing a blind and buried via circuit board according to claim 1, characterized in that: In S4, the specific steps of performing a second pattern transfer process on the copper foil surface of the laminate include: The copper foil surface of the laminate is subjected to a second pattern transfer process using the LDI pattern transfer process to locate the opening position of the blind hole; The DES process is used to etch the copper foil corresponding to the blind hole opening position to expose the corresponding epoxy resin glue under the copper foil.

8. A method for manufacturing a blind and buried via circuit board according to claim 7, characterized in that: In S4, the specific steps of sequentially performing chemical etching, copper deposition and electroplating on the blind hole opening position include: The epoxy resin glue corresponding to the bottom of the copper foil is etched with 92% to 98% concentrated sulfuric acid to obtain a core board with blind holes; The core board with blind holes is subjected to copper deposition and VCP hole filling electroplating in sequence to obtain a core board with blind buried holes.

9. A method for manufacturing a blind and buried via circuit board according to claim 1, characterized in that: In S5, the specific steps of processing the semi-finished product of the core board with blind buried holes include: For the core board with blind and buried vias, DES, AOI, solder mask, surface treatment, molding, testing and appearance inspection processes are carried out in sequence.

10. A blind buried via circuit board, characterized in that: The circuit board is manufactured by the method for manufacturing a blind buried via circuit board as described in any one of claims 1 to 9.

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