Manufacturing method of multi-stage blind hole interconnection structure and circuit board

Abstract

The invention discloses a manufacturing method of a multi-order blind hole interconnection structure and a circuit board, and the manufacturing method comprises the following steps: prefabricating lamination: prefabricating a circuit board with multiple layers of inner layer patterns, the circuit board comprising an inner base layer and an upper base layer, the inner base layer comprising a core board and a first copper layer arranged on the core board, and the upper base layer comprising a second copper layer arranged on the core board; at least two upper base layers are stacked on the first copper layer, each upper base layer comprises a dielectric layer and a second copper layer arranged on the dielectric layer, and the first copper layer and the second copper layer are each provided with an inner layer pattern and a hole pad; performing multi-step trepanning, performing trepanning from the outermost upper base layer to the first copper layer, and forming a copper hole in the hole pad of the second copper layer and forming a medium hole in the medium layer through laser according to the forming requirement of the blind hole so as to form a corresponding blind hole; and electroplating and hole filling: filling the blind holes in an electroplating manner and enabling the plurality of blind holes to be interconnected. The manufacturing period of the circuit board can be shortened, and the manufactured interconnection structure is good in reliability and convenient to produce and apply.

Description

Technical Field

[0001] The invention relates to the technical field of printed circuit board manufacturing, and in particular to a manufacturing method of a multi-level blind hole interconnection structure and a circuit board. Background Art

[0002] For the processing of the multi-level blind hole interconnection structure of the existing circuit board, the current main solution is to use the method of layer-by-layer processing of laser blind holes and hole-filling electroplating, and then add layers one by one to achieve multi-level blind hole interconnection. Figure 1 and Figure 2 During production, the inner layer pattern and hole pad are first processed on the copper layer on the surface of the core board, and then a dielectric layer and a copper layer are pressed on it, and then the outer dielectric layer and copper layer are laser-opened to form blind holes, and then the blind holes are electroplated and filled. After the inner layer pattern and hole pad are processed on the outer copper layer, the above-mentioned operations of pressing the dielectric layer and the copper layer, laser opening, and electroplating filling are repeated as needed until the multi-level blind hole interconnection structure is completed. This method requires multiple laser and electroplating filling, and the materials need to be circulated back and forth in different processing equipment. The processing and manufacturing cycle is long. In addition, such multi-level stacked holes have stress reliability problems, and the processing method needs to be improved. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a method for manufacturing a multi-level blind hole interconnection structure, which is beneficial to improving the alignment of the multi-level blind holes by first manufacturing a circuit board with a multi-layer inner layer pattern, and not performing a hole opening process on the hole pad in advance, thereby avoiding the exposure deviation and size uniformity problems caused by the pre-opening of the multi-level blind hole pad. Subsequently, the hole pad and the dielectric layer are laser-opened, and finally the holes are uniformly electroplated and filled, which is beneficial to improving the processing efficiency and shortening the manufacturing cycle. The reliability of the interconnection structure obtained is good and convenient for production and application.

[0004] The invention also provides a circuit board manufactured by adopting the manufacturing method of the multi-level blind hole interconnection structure.

[0005] According to the first aspect of the present invention, the method for manufacturing a multi-level blind via interconnect structure comprises the following steps:

[0006] Prefabricated lamination, prefabricating a circuit board with multiple inner layer patterns, the circuit board includes an inner base layer and an upper base layer, the inner base layer includes a core board and a first copper layer arranged on the core board, at least two upper base layers are stacked on the first copper layer, the upper base layer includes a dielectric layer and a second copper layer arranged on the dielectric layer, and the first copper layer and the second copper layer are both processed with inner layer patterns and hole pads;

[0007] Multi-stage hole opening, starting from the outer upper base layer farthest from the inner base layer, hole processing is performed toward the first copper layer, and hole processing is performed on the upper base layer according to the need for opening blind holes. Copper holes are opened at the hole pads of the second copper layer and dielectric holes are opened in the dielectric layer by laser, so that the copper holes and dielectric holes form corresponding blind holes;

[0008] Electroplating hole filling, filling blind holes by electroplating and interconnecting multiple blind holes.

[0009] The method for manufacturing a multi-level blind hole interconnection structure according to an embodiment of the present invention has at least the following beneficial effects: by first manufacturing a circuit board with a multi-layer inner layer pattern, and then laser drilling holes on the hole pads and dielectric layers of each layer to obtain a plurality of required blind holes, and then uniformly electroplating and filling the plurality of blind holes, it is beneficial to improve processing efficiency, reduce the reciprocating flow of materials in different processing equipment, shorten the manufacturing cycle, and interconnect the blind holes of each level by synchronous electroplating and filling, so that the reliability of the obtained interconnection structure is better and it is convenient for production and application.

[0010] According to some embodiments of the present invention, when performing the prefabrication lamination step, the inner layer graphics and hole pads are first processed on the first copper layer on the surface of the core board, and then the upper base layer is pressed layer by layer on the first copper layer. Each time a layer of the upper base layer is pressed, the inner layer graphics and hole pads are processed on the second copper layer of the upper base layer to obtain a circuit board with multiple layers of inner layer graphics.

[0011] According to some embodiments of the present invention, when performing the multi-stage hole opening step, the hole pads of the second copper layer and the dielectric layer are laser opened respectively in a layer-by-layer hole opening manner.

[0012] According to some embodiments of the present invention, when performing the multi-stage hole opening step, a copper hole is opened at the hole pad of the second copper layer by ultraviolet laser irradiation, and a dielectric hole is opened in the dielectric layer by infrared laser irradiation.

[0013] According to some embodiments of the present invention, when performing a multi-step hole opening step, the wavelength range of the ultraviolet laser used to open copper holes at the hole pads of the second copper layer is 100-500nm, and the wavelength range of the infrared laser used to open dielectric holes in the dielectric layer is 500-1600nm.

[0014] According to some embodiments of the present invention, when performing a multi-stage hole opening step, each time the hole pad of the second copper layer and the dielectric layer are laser opened, the same outer layer pattern target is used to align the circuit board.

[0015] According to some embodiments of the present invention, in the multi-stage hole opening step, the diameter size of the blind hole produced decreases from the outermost second copper layer to the inner first copper layer.

[0016] According to some embodiments of the present invention, in the multi-stage hole opening step, the ratio of the depth dimension of the blind hole / the diameter dimension of the blind hole is in the range of 0.5-2.

[0017] According to some embodiments of the present invention, after performing multi-step opening and before performing the electroplating hole filling step, the interior of the blind hole is cleaned by plasma processing, and then the inner wall of the blind hole is metallized by copper plating.

[0018] The circuit board according to the embodiment of the second aspect of the present invention is manufactured by using the manufacturing method of the multi-level blind hole interconnection structure according to the embodiment of the first aspect of the present invention.

[0019] The circuit board described in the embodiment of the present invention has at least the following beneficial effects: by adopting the above-mentioned method for manufacturing the multi-level blind hole interconnection structure, the manufacturing cycle of the circuit board can be shortened, and the blind holes of each level are simultaneously electroplated and filled to interconnect, so that the reliability of the manufactured interconnection structure is better and it is convenient for production and application.

[0020] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0022] Figure 1 It is one of the schematic diagrams of the processing scheme of the existing multi-level blind hole interconnection structure in the background technology of the present invention;

[0023] Figure 2 The second schematic diagram of the processing scheme of the existing multi-level blind hole interconnection structure in the background technology of the present invention;

[0024] Figure 3 A schematic diagram of manufacturing a circuit board with multiple layers of inner layer patterns in a method for manufacturing a multi-level blind via interconnect structure according to an embodiment of the present invention;

[0025] Figure 4 One of the schematic diagrams of a method for manufacturing a multi-level blind via interconnect structure according to an embodiment of the present invention;

[0026] Figure 5 This is a second schematic diagram of a method for manufacturing a multi-level blind via interconnect structure according to an embodiment of the present invention.

[0027] Reference numerals:

[0028] First-order blind via 101 , second-order blind via 102 , third-order blind via 103 , core board 110 , via pad 111 , dielectric layer 120 , dielectric via 121 , second copper layer 130 , copper via 131 . DETAILED DESCRIPTION

[0029] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0030] In the description of the present invention, it is necessary to understand that if it involves orientation description, the orientation or position relationship indicated by, for example, up, down, front, back, left, right, etc. is based on the orientation or position relationship shown in the drawings, which is 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 orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0031] In the description of the present invention, if the words such as several, greater than, less than, exceed, above, below, within, etc. appear, among which, several means one or more, more means more than two, greater than, less than, exceed, etc. are understood as not including the number itself, and above, below, within, etc. are understood as including the number itself.

[0032] If the first and second are described, they are only used to distinguish the technical features and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the sequence of the indicated technical features.

[0033] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0034] Reference Figure 1 and Figure 2Taking an eight-layer circuit board as an example, the processing scheme of the multi-level blind hole interconnection structure of the existing circuit board is explained: Step 1, first process the inner layer pattern and the hole pad 111 on the copper layer on the surface of both sides of the core board 110; Step 2, respectively press the dielectric layer 120 and the copper layer on the copper layer on both sides of the core board 110; Step 3, according to the blind hole processing needs, laser open the dielectric layer 120 and the copper layer on the two outer sides to form a third-level blind hole 103; Step 4, electroplate the third-level blind hole 103 Filling the hole; Step ⑤, processing the inner layer pattern and the hole pad 111 on the outer copper layer; Step ⑥, respectively pressing the dielectric layer 120 and the copper layer on both sides; Step ⑦, according to the blind hole processing needs, laser drilling is performed on the two outer dielectric layers 120 and the copper layer to form the second-order blind hole 102; Step ⑧, electroplating and filling the second-order blind hole 102; Step ⑨, processing the inner layer pattern and the hole pad 111 on the outer copper layer; Step ⑩, respectively pressing the dielectric layer 120 and the copper layer on both sides; Step In the first step, according to the blind hole processing requirements, laser drilling is performed on the dielectric layer 120 and the copper layer on the two outer sides to form a first-order blind hole 101; In the next step, the first-order blind hole 101 is electroplated to fill the hole, and the multi-order blind hole interconnection structure of the eight-layer circuit board is completed. This method requires multiple laser and electroplating filling, and the material needs to flow back and forth between different processing equipment. The processing and manufacturing cycle is long, and such a multi-order stacked hole structure has stratification and poor stress reliability of the structure.

[0035] Reference Figure 3 , Figure 4 and Figure 5 The present invention provides a method for manufacturing a multi-level blind hole interconnection structure, which comprises the following steps:

[0036] Prefabricated lamination, prefabricating a circuit board with multiple inner layer patterns, the circuit board includes an inner base layer and an upper base layer, the inner base layer includes a core board 110 and a first copper layer disposed on the core board 110, at least two upper base layers are stacked on the first copper layer, the upper base layer includes a dielectric layer 120 and a second copper layer 130 disposed on the dielectric layer 120, and the first copper layer and the second copper layer 130 are both processed with inner layer patterns and hole pads 111;

[0037] Multi-stage hole opening, starting from the outer upper base layer farthest from the inner base layer, hole processing is performed toward the first copper layer, and hole processing is performed on the upper base layer according to the need for opening blind holes, and copper holes 131 are opened at the hole pads 111 of the second copper layer 130 and dielectric holes 121 are opened in the dielectric layer 120 by laser, so that the copper holes 131 and the dielectric holes 121 form corresponding blind holes;

[0038] Electroplating hole filling, filling blind holes by electroplating and interconnecting multiple blind holes.

[0039] The present invention first manufactures a circuit board with a multi-layer inner layer pattern, then performs laser drilling on the hole pads 111 and the dielectric layer 120 of each layer to obtain a plurality of required blind holes, and then uniformly performs electroplating and hole filling on the plurality of blind holes, which is beneficial to improving processing efficiency, reducing the reciprocating flow of materials in different processing equipment, shortening the manufacturing cycle, and interconnecting the blind holes of each stage by synchronous electroplating and hole filling, so that the reliability of the obtained interconnection structure is better and it is convenient for production and application.

[0040] In some embodiments, when performing the prefabrication lamination step, the inner layer pattern and the hole pad 111 are first processed on the first copper layer on the surface of the core board 110, and then the upper base layer is pressed layer by layer on the first copper layer. After each layer of the upper base layer is pressed, the inner layer pattern and the hole pad 111 are processed on the second copper layer 130 of the upper base layer to obtain a circuit board with multiple layers of inner layer patterns.

[0041] It is understandable that if Figure 3 As shown, taking the production of a circuit board with eight layers of inner layer patterns as an example, during the prefabrication stacking step, a first copper layer (not shown) is provided on both side surfaces of the core board 110, and the inner layer patterns and hole pads 111 are first processed on the first copper layers on both sides, and then an upper base layer is respectively pressed on the first copper layers on both sides, and the second copper layer 130 is located on the outside, and then the inner layer patterns and hole pads 111 are processed on the second copper layers 130 on both outer sides, and then an upper base layer is respectively pressed on the second copper layers 130 on both outer sides, and after the inner layer patterns and hole pads 111 are processed on the second copper layers 130 on the outer side, an upper base layer is respectively pressed on the second copper layers 130 on both outer sides, and the inner layer patterns and hole pads 111 are processed on the second copper layers 130 on both outer sides, thereby obtaining a circuit board with eight layers of inner layer patterns. By laminating the base layer layer by layer and processing the inner layer graphics and the hole pad 111, the subsequent continuous hole opening operation is facilitated, and the hole pad 111 is not opened in advance, which is conducive to improving the alignment of the multi-level blind holes and avoiding the exposure deviation and size uniformity problems caused by the pre-opening of the multi-level blind hole pad 111.

[0042] In some embodiments, when performing the multi-stage hole opening step, the hole pad 111 of the second copper layer 130 and the dielectric layer 120 are respectively laser-opened by opening holes layer by layer. It is understandable that during the production, the hole pad 111 of the outermost second copper layer 130 is firstly opened by laser, and then the dielectric layer 120 of the next layer is opened, and then the hole pad 111 of the next layer is opened, and so on and so forth. The hole opening is performed layer by layer, and multiple laser openings are performed, which is conducive to improving the hole shape of the blind hole and improving the processing layer number capability of the multi-stage blind hole.

[0043] In some embodiments, when performing the multi-step hole opening step, the copper hole 131 is opened at the hole pad 111 of the second copper layer 130 by ultraviolet laser irradiation, and the dielectric hole 121 is opened in the dielectric layer 120 by infrared laser irradiation.

[0044] It is understandable that, since the absorption rate of metal copper increases with the decrease of wavelength, copper has a good absorption rate for ultraviolet laser, and the wavelength of ultraviolet laser is short, the processing heat affected zone is small, and the use of ultraviolet laser copper breaking is conducive to forming a copper hole 131 of the required diameter at the hole pad 111 of the second copper layer 130, which is convenient for the subsequent opening of the dielectric layer 120; since the material of the dielectric layer 120 has a good absorption rate for infrared laser, using infrared laser laser dielectric layer 120 to open holes is conducive to forming dielectric holes 121 of the required diameter and depth, which is convenient for processing to the surface of the hole pad 111 of the next layer, and is conducive to avoiding damage to the hole pad 111 of the next layer. The scheme of alternating multiple ultraviolet laser copper breaking and infrared laser laser dielectric layer 120 opening can further improve the processing layer capacity of multi-order blind holes and improve the hole shape of blind holes.

[0045] In some embodiments, when performing the multi-stage hole opening step, the wavelength range of the ultraviolet laser used to open the copper hole 131 at the hole pad 111 of the second copper layer 130 is 100-500nm, and the wavelength range of the infrared laser used to open the dielectric hole 121 in the dielectric layer 120 is 500-1600nm. By using the ultraviolet laser and infrared laser in the above wavelength range, it can be well applied to the hole opening operation of the hole pad 111 and the dielectric layer 120, and is easy to use.

[0046] When the hole pad 111 is opened, the energy, pulse frequency and pulse width of the ultraviolet laser are adjusted according to the thickness of the copper layer of the hole pad 111, so as to control the diameter of the copper hole 131. The thickness range of the ultraviolet laser copper breaking is 1 to 35 um, and the diameter is 15 to 500 um. When the dielectric layer 120 is opened, the energy, pulse frequency and pulse width of the infrared laser are adjusted according to the thickness of the dielectric layer 120, so as to control the thickness and diameter of the opening of the dielectric layer 120.

[0047] In some embodiments, when performing the multi-stage hole opening step, the same outer pattern target is used to align the circuit board each time the hole pad 111 of the second copper layer 130 and the dielectric layer 120 are laser-opened. It is understandable that by using the same outer pattern target to align the circuit board, it is helpful to ensure the alignment of the multi-stage blind hole processing, avoid the deviation of the blind hole, and facilitate use.

[0048] In some embodiments, in the multi-stage hole opening step, the diameter of the blind hole produced decreases from the outermost second copper layer 130 to the inner first copper layer. Figure 5 As shown, the diameter of the blind hole decreases from the outermost second copper layer 130 to the inner first copper layer, so that the hole wall of the blind hole has a certain taper change, and the hole diameter decreases as the depth of the hole increases, which is beneficial to the subsequent electroplating filling and is easy to use.

[0049] In some embodiments, in the multi-stage hole opening step, the ratio of the depth dimension of the blind hole / the diameter dimension of the blind hole is in the range of 0.5 to 2. By controlling the ratio of the depth dimension of the blind hole / the diameter dimension of the blind hole in the range of 0.5 to 2, it is convenient for subsequent electroplating hole filling.

[0050] In some embodiments, after performing the multi-step opening and before performing the electroplating hole filling step, the interior of the blind hole is cleaned by plasma processing, and then the inner wall of the blind hole is metallized by copper plating.

[0051] It is understandable that before the electroplating hole filling step, the inside of the blind hole is cleaned by plasma processing to remove the residual glue residue in the hole, and then copper is processed to metalize the inner wall of the blind hole to facilitate the subsequent electroplating hole filling.

[0052] Reference Figure 4 and Figure 5 Taking the interconnection of the first-order blind via 101, the second-order blind via 102 and the third-order blind via 103 in an eight-layer circuit board as an example, the method for manufacturing the multi-order blind via interconnection structure of the present invention is specifically described:

[0053] A circuit board with eight inner layer patterns is manufactured, wherein the inner base layer is provided with upper, middle and lower upper base layers on both sides, and hole pads 111 of multi-step blind holes are pre-made in the first copper layer and the second copper layer 130;

[0054] Using the outer layer pattern target alignment, the hole pad 111 of the upper second copper layer 130 is laser-broken at a preset position using a 354nm wavelength ultraviolet laser, the copper breaking thickness is 18um, and a copper hole 131 with an opening diameter of 120um is formed;

[0055] Using the same outer layer pattern target for alignment, a carbon dioxide infrared laser with a wavelength of 1064nm is used to laser open a dielectric hole 121 in the dielectric layer 120 at the position of the upper copper hole 131. The upper copper hole 131 and the dielectric hole 121 form a first-order blind hole 101 with a depth of 50um, an upper aperture of 120um, and a lower aperture of 100um.

[0056] Using the same outer layer pattern target alignment, laser copper breaking is performed on the hole pad 111 of the second copper layer 130 of the middle layer at a preset position using a 354nm wavelength ultraviolet laser. The copper breaking thickness is 18um, forming a copper hole 131 with an opening diameter of 100um.

[0057] Using the same outer layer pattern target alignment, a carbon dioxide infrared laser with a wavelength of 1064nm is used to laser open a dielectric hole 121 in the dielectric layer 120 at the position of the middle layer copper hole 131. The middle layer copper hole 131 and the dielectric hole 121 form a second-order blind hole 102 with a depth of 50um, an upper aperture of 100um, and a lower aperture of 80um.

[0058] Using the same outer layer pattern target alignment, the hole pad 111 of the lower second copper layer 130 is laser-broken at a preset position using a 354nm wavelength ultraviolet laser, the copper breaking thickness is 18um, and a copper hole 131 with an opening diameter of 80um is formed;

[0059] Using the same outer layer pattern target alignment, a carbon dioxide infrared laser with a wavelength of 1064nm is used to laser open a dielectric hole 121 in the dielectric layer 120 at the position of the lower copper hole 131. The lower copper hole 131 and the dielectric hole 121 form a third-order blind hole 103 with a depth of 50um, an upper aperture of 80um, and a lower aperture of 60um.

[0060] The inside of each level of blind holes is cleaned by plasma processing to remove residual glue residue in the hole, and then copper is processed to metalize the hole wall. Then, the blind holes of each level are filled and interconnected by electroplating.

[0061] The present invention does not pre-process the hole pad 111 of the second copper layer 130. After the circuit board with multi-layer inner layer patterns is completed, a processing scheme of multiple ultraviolet laser hole pad 111 openings + infrared laser medium layer 120 openings is adopted, which can further improve the processing layer number capacity of the multi-order blind hole, which is beneficial to improving the hole shape and alignment of the multi-order blind holes, and avoiding the exposure deviation and size uniformity problems caused by pre-etching copper holes 131 of the multi-order blind holes. After obtaining multiple required blind holes, the multiple blind holes are uniformly electroplated and filled, which is beneficial to improving processing efficiency, reducing the reciprocating alternating flow of materials in different processing equipment, shortening the manufacturing cycle, and the blind holes of each order are synchronously electroplated and filled to interconnect, so that the reliability of the obtained interconnection structure is better and convenient for production application.

[0062] In actual application, the inner base layer can also be provided with an upper base layer on one side, and the number of upper base layers on one side can also be two layers, four layers or more. The thickness of each second copper layer 130, the thickness of the dielectric layer 120, the laser wavelength used for laser opening, etc. can all be set accordingly according to actual use needs.

[0063] The circuit board according to the second aspect of the present invention is manufactured by the method for manufacturing the multi-level blind hole interconnection structure according to the first aspect of the present invention.

[0064] The circuit board according to the embodiment of the present invention can shorten the manufacturing cycle of the circuit board by adopting the above-mentioned method for manufacturing the multi-level blind hole interconnection structure. The blind holes of each level are simultaneously electroplated and filled to interconnect, so that the reliability of the manufactured interconnection structure is better and it is convenient for production and application.

[0065] Since other components of the circuit board according to the embodiment of the present invention are known to those skilled in the art, they will not be described in detail here.

[0066] The embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the knowledge scope of ordinary technicians in the technical field without departing from the purpose of the present invention.

Claims

1. A method for manufacturing a multi-level blind hole interconnection structure, characterized in that: The following steps are involved: Prefabricated lamination, prefabricating a circuit board with multiple inner layer patterns, the circuit board includes an inner base layer and an upper base layer, the inner base layer includes a core board and a first copper layer arranged on the core board, at least two upper base layers are stacked on the first copper layer, the upper base layer includes a dielectric layer and a second copper layer arranged on the dielectric layer, and the first copper layer and the second copper layer are both processed with inner layer patterns and hole pads; Multi-stage hole opening, starting from the outer upper base layer farthest from the inner base layer, hole processing is performed toward the first copper layer, and hole processing is performed on the upper base layer according to the need for opening blind holes. Copper holes are opened at the hole pads of the second copper layer and dielectric holes are opened in the dielectric layer by laser, so that the copper holes and dielectric holes form corresponding blind holes; Electroplating hole filling, fill the blind holes by electroplating and interconnect multiple blind holes.

2. The method for manufacturing a multi-level blind via interconnect structure according to claim 1, characterized in that: During the prefabrication lamination step, the inner layer pattern and hole pad are first processed on the first copper layer on the surface of the core board, and then the upper base layer is pressed layer by layer on the first copper layer. Each time a layer of the upper base layer is pressed, the inner layer pattern and hole pad are processed on the second copper layer of the upper base layer to obtain a circuit board with multiple layers of inner layer patterns.

3. The method for manufacturing a multi-level blind via interconnect structure according to claim 1, characterized in that: When performing the multi-stage hole opening step, the hole pads of the second copper layer and the dielectric layer are laser opened in a layer-by-layer manner.

4. The method for manufacturing a multi-level blind via interconnect structure according to claim 3, characterized in that: When performing the multi-stage hole opening step, a copper hole is opened at the hole pad of the second copper layer by ultraviolet laser, and a dielectric hole is opened in the dielectric layer by infrared laser.

5. The method for manufacturing a multi-level blind via interconnect structure according to claim 4, characterized in that: When performing the multi-stage hole opening step, the wavelength range of the ultraviolet laser used to open the copper hole at the hole pad of the second copper layer is 100-500nm, and the wavelength range of the infrared laser used to open the dielectric hole in the dielectric layer is 500-1600nm.

6. The method for manufacturing a multi-level blind via interconnect structure according to claim 3, characterized in that: When performing the multi-stage hole opening steps, each time the hole pad of the second copper layer and the dielectric layer are laser opened, the same outer layer pattern target is used to align the circuit board.

7. The method for manufacturing a multi-level blind via interconnect structure according to claim 1, characterized in that: In the multi-stage hole opening step, the diameter of the blind hole produced decreases gradually from the outermost second copper layer to the inner first copper layer.

8. The method for manufacturing a multi-level blind via interconnect structure according to claim 7, characterized in that: In the multi-stage hole opening step, the ratio of the depth dimension of the blind hole to the diameter dimension of the blind hole is in the range of 0.5-2.

9. The method for manufacturing a multi-level blind via interconnect structure according to claim 1, characterized in that: After the multi-step opening and before the electroplating hole filling step, the inside of the blind hole is cleaned by plasma processing, and then the inner wall of the blind hole is metallized by copper treatment.

10. A circuit board, characterized in that: The multi-level blind hole interconnect structure is manufactured by the manufacturing method according to any one of claims 1 to 9.

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